Astronomy, Near Space, and Robotics

The Plan 8 from Outer Space Video

2012-01-23T08:13:00.000-08:00

I created this short video for my new robot, Plan 8 from Outer Space. I recently added a robotic arm to the robot and ended the arm with a red photometer. It's now a good model of a planetary rover.

Plan 8 From Outer Space

2012-01-17T06:50:00.001-08:00

I've nearly completed my latest robotics project, a radio instructed robot, or rover. The robot does not respond to joystick commands like a game. Instead, Plan 8 from Outer Space receives text instructions from a radio terminal. The commands are parsed and then acted on as long as they are valid. Except for it's robotic arm, the rover is complete.

Here's a list of the commands the rover can act on.
1. Move forwards or backwards
2. Move sideways left or right
3. Move diagonally, forwards or backwards and left or right
4. Pivot in place
5. Turn clockwise or counterclockwise while moving forward or backward
6. Collect photometer data now or over time
7. Pivot a camera left or right within a 90 deg arc
8. Turn on its two laser (indicates the width of robot in video images)
9. Give range data to objects (five angles within 45 deg left and right)
10. Report body tilt

Eventually Plan 8 from Outer Space will be outfitted with an arm to measure the level of radioactivity within a sample.

The robot has an articulated body that twists as it drives over obstacles. The four wheels are driven and are independently steered. Several new NearSys kits are incorporated into the robot, so look for these soon.

1. Smart Sonar (scanning sonar)
2. Accelerometer (used to measure tilt of the robot body)
3. CheapBot-20 robot controller (based on the PICAXE-20) which steers four independent wheels, drives two banks of motors, and has eight I/O ports
4. Bi-directional radio terminal

A side view of my new rover

A front view of my new rover

Thermal Vacuum Chamber

2011-11-21T07:10:00.000-08:00

I finally have a thermal vacuum chmaber (TVC) design I like. It's called Near Space in a Can and it will sell for $250 as a kit plus shipping (minus the vacuum pump since it's cheaper to pick that up at the store than sell it).

The TVC has a diameter and depth of nine inches. It's exterior is packed with dry ice and it's then pumped down. Inside the environment approaches near space conditions. I'll add radioactive materials and evnetually UV sources to more faithfully replicate near space.

As long as you're willing to pay postage, I will expose experiments (not living objects, please) to the chamber at no other cost. Eventually I'd like to have several of these available for amateur testing.

NearSys 11N

2011-11-15T06:59:00.001-08:00

Hard to believe, but I flew my 99th near space mission this weekend as NearSys 11N. I traveled to Valley, Nebraska to launch a ballon in conjunction with friend, Mark Conner. Mark and I go back to 1998 when we met at the St. Joe Hamfest in Missouri.

We ran into a small problem on this flight that ended up creating a bigger headache before it was all over. The helium tank we received was not properly topped off (about 20% low). As a result of the unexpectedly lower volume of helium, we were forced to remove some payloads. The reduction in payload weight also meant the parachute would descend slower, permitting a longer recovery.

To make a long story short, recovery should have occured in farm fields south of Anita, Iowa. Instead, recovery occurred in a small patch of woods near Adair. As is typical, the near spacecraft recovered on the very top of the trees. It took about an hour for Mark and me to retrieve the payload.

You can view the flight data on my website at, http://nearsys.com/arhab/flightdata/2011/n/index.htm.

Mark posted pictures at, https://picasaweb.google.com/111334632256807627139/NearSysFlight12Nov2011

Onwards and Upwards

Flight Number 99

2011-11-15T06:47:00.000-08:00

Introducing BalloonSats

2011-10-20T12:48:00.000-07:00

Introducing BalloonSats

An alternative to using robotics as a vehicle for teaching STEM is the BalloonSat project. One reason BalloonSats may make a superior alternative to robotics is that robotics doesn’t involve as much science and mathematics as a well structured BalloonSat project. And while robots in competition can operate in either autonomously (independent of a human operator) or with operator control (by human control, usually over a radio), BalloonSats can only operate in autonomous mode. Students design and program their BalloonSat to operate sensors and collect data without human intervention.

Description of a BalloonSat

BalloonSats, as Linda Kehr describes them, are model satellites carried under helium filled weather balloons to altitudes in excess of 80,000 feet, a very space-like environment. In fact, BalloonSat flights reach 85,000 feet easily and can reach over 120,000 feet with lighter payloads and larger balloons.

BalloonSats are the first step in the National Space Grant Satellite Program’s strategy, “crawl, walk, fly, run”, whose ultimate goal is to send a student-designed payload to Mars. However, the first step, “crawl” is designed to encourage students to build and fly simple models of satellites, like BalloonSats. It is believed that by getting students involved in a series of more complex projects, more will graduate from STEM programs and enter into aerospace engineering fields.

Description of their construction

BalloonSats are an inexpensive way to access space while still retaining some of design and engineering challenges of satellites (Kohler 2003).

Airframe

BalloonSats are student designed from Styrofoam to carry programmable dataloggers and cameras and typically do not weigh more one pound (Kennon, Roberts & Fuller 2008). Other design challenges may involve volume (not to exceed 1000 cc), minimum datalogging capability (internal and external temperatures over the entire flight) and functional testing preflight. Adhesives used to assemble the BalloonSat airframe from foamcore include silicon rubber glue, hot glue, and JB Weld (an epoxy). Aluminum duct tape is also a popular material to seal the airframe (Koehler 2003).

Figure 1. Example of a BalloonSat. This one is constructed from a sheet of ½” thick Styrofoam, the same material used as insulation of outside house walls. It’s walls are assembled with hot glue and covered in black packaging tape. Photograph from the author’s collection.

Avionics

The datalogger used when BalloonSats were first designed is the Hobo datalogger. Scouts involved with the Glenn Research Center’s BHALF (BalloonSat High Altitude Flight) are beginning to experiment with using BASIC Stamps by Parallax – the same microcontroller used in the Boe-bot robot (BHALF). For Students in CU Boulder’s Gateway to Space course who are ready for a more advanced challenge, the timer is replaced with a programmable BASIC Stamp.

After recovery of their BalloonSat, students connect the datalogger and camera to a PC to retrieve the data and images. Students can perform their own mathematical analysis of the data and images or rely on the software used to program the dataloggers.

Figure 2. An eight-bit Hobo datalogger manufactured by OnSet Computing. This model records internal temperature and an external voltage. Photograph from the author’s collection.

A one time popular camera for BalloonSats was the Canon Elph. These APS film cameras were relatively inexpensive and very easy to modify for operation by intervalometers. The intervalometer is a 555 IC based timer kit soldered together by students. More recently, digital cameras and digital video recorders are included in the BalloonSats.

Preflight testing

Prior to flight, their designers test their BalloonSats. Even though flights cost less than $300, this is still too expensive to launch a BalloonSat that has no guarantee of functioning properly. Typical tests used in Koehler’s program include the following.

Drop Test: BalloonSats land by parachute. At touchdown, the BalloonSat’s speed can easily reach 10 mph. To ensure BalloonSats will remain in one piece during the landing, students drop their BalloonSats from a height that simulates their landing of 10 mph. The height from which a BalloonSat must be dropped to simulate a 10 mph landing can be calculated as shown below.
10 mph * 5280 ft/mile * 1 hour/60 minutes * 1 minute/60 seconds = 32.2ft/s2 * t
time of fall = 0.455 seconds
h = ½ * 32.2 * (0.445)2
height of drop = 3.34 feet

Cooler Test: Near space gets very cold (the coldest temperature the author’s BalloonSats have measured is -90O F, although -60O F is more typical). To ensure the BalloonSat is build well enough to keep its datalogger contents warm enough to function is to place the BalloonSat inside a Styrofoam ice chest filled with dry ice. The BalloonSat is left inside the cooler long enough to let the interior temperature bottom out (the author uses a time of 20 to 30 minutes).

Functional Tests: During its construction and at the competition, the BalloonSat, its datalogger, intervalometer, and camera are tested together to verify they will work without interfering with each other. This means all subsystems must fit inside the airframe without blocking access to the camera power button or the camera’s view outside the airframe.

Description of launch/recovery

BalloonSats are lofted into near space on a helium-filled weather balloon. The entire vehicle consists of a helium-filled weather balloon at the top, a recovery parachute attached below the balloon by a load line of nylon cord, one or more GPS trackers packed inside a Styrofoam enclosure, and one or more BalloonSats (Koehler 2003). The GPS tracker transmits position reports of the balloon over amateur radio frequencies. The system amateur radio operators use to track the location of items (like automobiles) is called the Automatic Packet Reporting System, or APRS. Therefore, a licensed amateur radio operator is required on each near space launch. The expendable parts of the flight are the helium and latex weather balloon and accounts for the $300 price tag for the flight. The radio tracking equipment are repaired, if necessary, so it can track another mission.
Recently, Taylor University began marketing a license-free version (900 MHz spread-spectrum) of the radio tracker. The system is called the High Altitude Research Platform (HARP) and is marketed by StratoStar. To date, over 200 flights using the StratoStar system have taken place.

The maximum weight on most BalloonSat launches is 12 pounds as long as no single item weighs more than six pounds nor has a surface density greater than one ounce per square inch. Additional FAA rules apply when these limits are exceeded (Federal Aviation Administration, FAR 101). Therefore, to avoid the application of additional FAA procedures, most schools launching BalloonSat limit their flights to 12 pounds total weight.

The typical BalloonSat launch occurs in the morning and requires between two and three hours to complete. The early morning launch permits the balloon to be filled while the winds are generally lower. After release, the typical ascent rate for the weather balloon and payload is 1,000 feet per minute. Latex weather balloons are sold by weight and frequently used balloons are 1200 and 1500 grams. Kaymont is an example of weather balloon dealer located in the United States.

A balloon filling system consisting of a regulator designed for welding gases, oxygen hose, and a length of PVC pipe. The PVC pipe attaches to the end of the oxygen hose and has a diameter less than the diameter of the balloon’s nozzle. The balloon nozzle slides over the PVC pipe and taped securely. Once secured, the balloon is filled with helium. Welding companies are the suppliers of helium required to launch a weather balloon. The helium arrives in welding tanks and they can weigh as much as 120 pounds.

Figure 5. Balloon Filler. The green oxygen hose is 12 feet long and the PVC pipe is 1.25 inches outside diameter. Photograph from the author’s collection.

Figure 6. University of Kansas students filling two latex weather balloons in preparation for BalloonSat launches. Photograph from the authors collection.

A typical flight requires 90-100 minutes to climb to peak altitude and approximately 30 minutes to descend back to the ground on its parachute. Because of the amateur radio equipment onboard, the balloon is tracked and its landing site located. Because of APRS onboard the balloon, students can track the position of the balloon carrying their BalloonSat in real time (Koehler 2003).

Near Space

According to Aerostar, near space begins at an altitude of 50,000 feet. According to the United States Air Force, near space begins at 20 km (65,600) feet, or above class A airspace.

Figure 7. Example of air pressure measured as a function of altitude by a BalloonSat. Environmental sensors from this author’s past near space flights indicate the air pressure drops to 10 mb, or 99% of a vacuum at an altitude of 100,000 feet (Data from the author’s collection).

Figure 8. Example of air temperature measured as a function of altitude by a BalloonSat. Air temperature drops to a low of -60O F in the summer and lower in the winter at the boundary between the troposphere and the stratosphere (Data from the author’s collection).

Figure 9. Example of the relative humidity measured as a function of altitude by a BalloonSat (Data from the author’s collection).

Figure 10. Example of cosmic ray flux measured as a function of altitude by a BalloonSat. The flux of secondary cosmic rays increases as the altitude increases until well into the stratosphere, where primary cosmic rays begin to be detected (From author’s personal data).

Figure 11. Example of an image returned by a BalloonSat showing the blackness of space and the curvature of the earth. A digital camera modified for operation by a programmable flight computer recorded this image of near space at an altitude of 78,000 feet (Image from the author’s collection).

Infrared for Digital Cameras

2011-10-13T19:36:00.001-07:00

I began an investigation into adapting the cameras in my dissertation BalloonSat kit for infrared use. If you've looked for IR filters recently, you'll find they get pretty expensive. In place of a traditional IR filter, I made one according to the directions of Bill Beatty. He recommended using several layers of Congo Blue lighting gels and one of Primary Red. The blue gels are so dense in color that they block most of the visible light trying to get through them, so only a little of the blue gets though. The red gel manages to block the small amount of blue that gets through.

Stage lighting gels must be transparent to IR or else they will get too hot and melt. So if they can be stacked to block visible light, then only IR is going to get through them.

Digital cameras are naturally sensitive to IR. In fact, they need IR blocking filters to keep the appearance of their images looking like we expect. Now the camera must adjust its exposure time to compensate for the purely IR image, but my dissertation camera can handle it. I'll have to look into the effects of increased exposure time and the unsteady tripod that a BalloonSat simulates. However, if this is not too much of an issue, I expect two cameras, one with IR filter and one without, to make a great near space experiment for students.

This is the visible image taken on Wednesday afternoon. Pretty normal looking.

This is the infrared image taken on Thursday afternoon. Notice how bright the tree leaves appear. Chlorophyll is very reflective in IR. Also note how much brighter the trees are than the apartments behind them in IR (but not visible).

Mars and the Beehive Star Cluster

2011-10-01T09:03:00.000-07:00

The planet Mars is traversing the Beehive star cluster. The picture below was taken the morning of September 30th, at 4:30 AM. The digital camera was set for a six power optical zoom and 15 second exposure. The resulting file was enhanced and sharpened using GIMP. It's not too bad for a camera tripod in Topeka.

LED Photometers

2011-08-30T11:59:00.000-07:00

Many years ago, I read an interesting article (http://www.opticsinfobase.org/abstract.cfm?URI=ao-31-33-6965) at the Physics Department at K-State. In it, Forest Mims discussed using LEDs as frequency specific light detectors. I've played with LEDs off and on for several years before finally following Forest's recommendations and making a descent LED photometer.

While they're not quite ready yet, Nearsys will soon offer LED photometer kits for near space use. The kit comes with a PCB for two LEDs and a temperature sensor. The temperature sensor is required because the light sensitivity of LEDs is strongly dependent on their temperature. It should be an easy process to calibrate the photometer with a styrofoam box and dry ice.

This design of two LEDs and a temperature sensor permits you to compare the relative brightness of sunlight in two different portions of the spectrum. The LEDs I'm in the process of testing now are 940 nm IR and 850 nm IR. I've selected these two because according to Forest's notes, the ratio between the two can be used to measure the amount of water vapor in the air. The amount of water vapor should change dramatically during a near space flight and is an example of the remote sensing that can be performed with BalloonSats. Next up will be to find other LED combinations that will provide interesting information.

You can read more about LEDs and Forest's discovery at http://www.sas.org/tcs/weeklyIssues_2009/2009-01-02/feature1/index.html and http://www.sunandsky.org/Sun_and_Sky_Data.html.

The complete photometer kit. It comes with the photometer head (with its three sensors), transconductance amp, and easy plug for connecting to a NearSys flight computer. I want to thank Mr. Forest Mims for helping me design this photometer and encouraging me to experiment with it in near space.

Changes in the American Economy

2011-08-15T06:44:00.000-07:00

Our economy and its interaction with the rest of the world is rapidly changing. In response to concerns expressed by several of the national academies and my interest in near space, I am preparing a research project that incorporates science, technology, engineering, and mathematics, or STEM.

The United States no longer produces the majority of its wealth by manufacturing products for local markets. Instead, services, information, and innovation are our largest sources of revenue. Even when the US does create new products, much of the manufacturing eventually moves overseas. And increasingly, more research is moving overseas as Chinese and Indian students receive good educations

In order to work in occupations involving information and innovation, future employees, that is, our students, must be adequately trained in STEM. For several reasons, this is not the case. One reason students don’t receive a strong STEM education is that there are many teachers not adequately prepared to teach an integration of science, technology, engineering, and mathematics. Even when teachers are well prepared to teach STEM, they lack the real world activities that incorporate STEM. The activities they select must be stimulating in order to prevent students from tuning out.

Rising Above the Gathering Storm: A Report
In 2005, the national academies of science and engineering, the institute of medicine and the national research council were tasked to determine issues and solutions to US prosperity in the 21st century. The commission determined there are two overarching goals to meet if we want to maintain our national prosperity

First is to create more high tech jobs.
Second, to develop additional energy sources that are clean and reliable.

To create more high tech jobs and create additional supplies of clean and dependable energy of the 21st century, The commission developed recommendations in four broad areas. To meet those recommendations, there are 20 specific actions the US needs to take. The four recommendations involve the following areas.

1. K through 12 education
2. Research
3. Higher education
4. Economic policy

I will focus on the K through 12 education recommendations and its actions

The commission concludes it will take 10,000 additional, highly qualified math and science teachers every year to create STEM literacy in the majority of the US student population within the next ten years. It takes time to train college students to become teachers. However, right now, we need 250,000 teachers able to teach challenging subjects. One way to reach this goal is to teach these teachers (in summer classes) how to teach Advanced Placement and International Baccalaureate subjects back in their schools. The United States could consider creating national STEM programs and standards. These standards would need to be taught to currently active teachers (again through summer classes). Finally, the US must invest in the classroom to create more students prepared to take STEM majors in college. The truth is that our future scientists and engineers begin in 6th grade

I want to address one way we may be able to help students prepare now

Before students can become STEM smart, they need to study STEM subjects. And they need to study them diligently. So what makes students want to study difficult subjects?

Myers and Fouts in their study “A cluster analysis of high school science classroom environments and attitude toward science” state that positive attitudes to subjects are associated with higher levels of student involvement in those classes. In other words, students must have a positive attitude toward STEM subjects in order to want to spend the time necessary to acquire a high level of STEM knowledge.

Osborne in, “Attitudes towards science: a review of the literature and its implications” states that one reason students don’t like science is that they see their science class as a history of great ideas. There aren’t enough in-class applications of how science is being done today. To them, the science class is boring. Osborne also states that three of the many factors influencing students’ attitudes towards science include the following.

1. Their enjoyment of science
2. Their past achievement in science
3. And the nature of the classroom environment

In a school district were meeting state standards is the most critical part of the school year, good extracurricular activities become a more important vehicle to positively influence student attitudes towards STEM. That’s because the regular classroom doesn’t have the time for exploration or open-ended investigation. By good after school activities, I mean those that model real world science in action, that are enjoyable, and have high levels of successful completion.

Some good STEM activities in use today include FIRST robotics, BEST Robotics, and Project Lead the Way.

So in a nutshell, the nature of the American economy is changing and has been changing fast for the last 50 or so years. If our students want high paying, stimulating careers, they need to be prepared for STEM occupations. Schools in many cases could use some help finding meaningful and interesting STEM activities. This is one reason resort to robotics. However, it seems to me that the science and mathematics aspect of robotics is lacking. Based on my experience, I have propose there is a better vehicle than robotics for STEM education.

Welcome to my Dissertation

2011-08-12T06:31:00.000-07:00

To date, I have found several articles on near space and BalloonSats in an educational setting. Some describe how a near space program was set up, how one is operated, and some of the experiments college level students are performing. However, I have found no dissertations or studies showing the effect of a BalloonSat project on student interests in science. My plan is to address this issue.

My research plan involves creating a BalloonSat challenge similar to the successful FIRST robotics challenge. Student teams will have a limited time to design, construct, and test a BalloonSat design. There is no actual competition between teams; however, students will need to send their BalloonSat back to me before their deadline. I will launch the BalloonSats for all the teams and expect them to reach 90,000 feet. After recovery, the BalloonSats will be returned to their respective schools so that each team can download and analyze the data. Students will have two weeks to process their data and post the results in a web-based report.

Student interest in science will be measured twice, once before the project begins and then one last time after the reports are completed. I also plan to select a convenience sample of students to interview. The results of the surveys, the team reports, and interviews will be the data of my study.

I have designed the BalloonSat kit and selected the science interest inventory. Over the next couple of weeks, I discuss my plans in greater detail and continue asking for volunteers. In the hopes that I can get more classrooms to volunteer, the BalloonSat kits will be free and will the flight. After the study is complete, classrooms will be allowed to keep their BalloonSat. As long as they can find a balloon group, it can be reprogrammed and launched again and again.

Please consider being a part of this study. As I said earlier, no study like this has been done in the past.

Participating classes could get images and data like this.

2011-06-27T06:18:00.000-07:00

NearSys is in the process of creating a complete robotics kit. The kit incorporates the CheapBot body (updated version), a robot controller, line follower, and adapter cable in a single bag of parts. The assembled robot can be programmed for maze driving and line following.

The new body uses pre-drilled and shaped Sintra, just bolt it together. New servo brackets attach the motors to the bottom deck, there is no more wood in the robot body. The CheapBot is all proper metal and plastic.

The robot body is pre-drilled for robotic arms and the smart proximity detector. Future upgrades include a radio terminal (for communicating with the robot) and a beacon locator.

The price for the complete CheapBot-14 robot kit is to be about $80 plus shipping and handling. In another week a CheapBot-18 version will be available.

Balloon CubeSat

2011-06-05T11:20:00.000-07:00

In preparation of my dissertation, I am experimenting with different BalloonSat configurations. Here, I am attempting to replicate a CubeSat. The requiements are a 10 cm cube weighing no more than 1 kg.

The airframe is made from 10mm thick Cellfoam 88. Since it has a hard flat surface, I was able to glue Styrene plastic to it without it melting very badly. I filled in gaps with Gorrila glue.

The Balloon CubeSat measures two temperatures, internal and external. The flight computer is based on a BalloonSat Mini and will make measurements once per minute during the mission. It is my hope that a project like this will make a great introduction to satellites.

NearSpace UltraLight

2011-01-23T14:37:00.001-08:00

The UltraLight kit is just about ready for sale (I'm waiting for some PICAXE-28X's and to complete the directions). I've added a bunch of new stuff to the kit, including a control panel, commit tag, audio beacon, and antenna, as you can see in the picture above.

The NearSpace UltraLight is the easiest way to begin a near space program. The kit can be assembled over a weekend. All you need to complete the kit is decide on your battery and its termination (I use Anderson Powerpoles). If you have cameras, then you'll also need to select a termination method for them (I recommend Dean's micro plugs).

NearSys sells a GPS receiver kit. It is designed for flight computers like the UltraLight. The UltraLight and GPS coupled together is a complete flight computer. Build an airframe and purchase a parachute and you can begin exploring near space.

About the Flight Computer

The UltraLight digitizes four analog sensor voltages, operates three digital experiments (like geiger counters), controls two cameras, and positions two servos (the servos have their own battery). The UltraLight's audio beacon makes enough noise that you can locate the near spacecraft in tall grass or corn fields. The control panel lets you program the flight computer and download data without having to open the airframe. You can also communicate with the flight computer while launch crews are filling the balloon (perhaps to verify sensor operation prior to launch). The flight computer's Tiny Trak is also assessible through the control panel (but not while the GPS is plugged in) The control panel indicates the near spacecraft's power status and the status of the Tiny Trak (that is, when it is transmitting and when its GPS has a lock). The bright red commit tag screams a reminder to begin the mission before releasing the balloon. That way you can power up the near spacecraft and wait for a GPS lock before recording mission data (who wants a bunch of data on the ground when you're headed to 100,000 feet?).

The Onboard Tiny Trak

The APRS tracker is built right into the flight computer. The 500 mW transmitter and dipole antenna will let you track the entire mission. Since the transmitter is set for 144.390 MHz, I-Gates can put your tracking data online, allowing everyone in the world to track your flight (very useful when your chase vehicle is located in the null of the antenna).

Mission Data

Mission data is stored in 32kB of memory. After recovery, reprogram the flight computer to download its data right into your PICAXE Editor (with its built-in terminal program). This can be done right in the field if your want (bring your netbook along). The data is then saved as a text file and opened in Excel. You can be generating results from the mission at the post recovery lunch!

It may take another week to get the kits packed and the directions in their first draft. Meanwhikle, feel free to contact me if you have questions.

I guess it's time to start a forum!

A Complete Near Space Flight Computer

2011-01-19T19:41:00.000-08:00

I finally received the ten 144.390 MHz transmitters I ordered for near space flight computer kits. In the interim, I developed GPS and antenna kits. The picture above shows what a complete flight computer kits looks like.

Shortly, beginners will be able to purchase a complete near space flight computer. After assemblying the kit, all you will need is a parachute, battery, and airframe. The kit will include a control panel to communicate and control the flight computer from outside the airframe, a 2m dipole antenna, GPS receiver tested to 103,000 feet, audio locator beacon, and programmable flight computer.

The first kit is based on the PICAXE-28 and the second based on the BASIC Stamp. Check the NearSys website (nearsys.com/catalog) for information as I get my updates in order. Until then, feel free to contact me through email.

Near Space in a Can

2011-01-14T15:47:00.001-08:00

The Near Space in a Can thermal vacuum chamber is about ready for retail. The image above is missing its vacuum gauge, which is at school. Otherwise, you now get a good idea of what it will look like. The kit should be no more than $150.

Just pack the Near Space in a Can with dry ice and let it chill before loading the test subject inside. Then pump it down with your vacuum pump. The environment inside will match near space conditions.

The stainless steel canister is 7.5 inches in diameter and 7.5 inches deep. The clear plexiglass cover lets you observe the experiment inside and even video tape the test.

A future upgrade will bring wiring inside so you can communicate with experiments inside.

Single Axis Arm with Snare End-Effector

2011-01-09T13:22:00.000-08:00

I completed my design of a single axis robotic arm. The servo lifts and lowers the arm like a traditional arm. What is different is the end effector that allows the arm to pick up objects. It's a wire snare, similar to the end effector on the Space Shutter robotic arm. A mini servo extends and retracts the wire snare, letting it wrap around and tighten around th object to be picked up.

Look for a magazine article (in Servo) and a kit to made available shorty.

Near Space in a Can

2011-01-01T18:52:00.000-08:00

I ran the first tests of a new thermal vacuum chamber. It's a stainless steel can with vacuum and cable ports. The can fits inside a plastic ice chest that can be packed with dry ice (see my Nuts and volts article on this subject).

The front of the chamber is sealed with thick acrylic plastic to permit observations of the interior of the chamber during testing. The cable port permits power to enter the chamber for its ultraviolet source and temperature sensor. Pressure inside the chamber is monitored with an analog pressure gauge.

I call the thermal vacuum chamber, Near Space in a Can. It's the second simulator NearSys will sell (the GPS simulator is the first). Near Space in a Can is large enough to test BalloonSats and CubSats.

Near Space in a Can will be available from NearSys in 2011 as an affordable kit.

Robot Terminal

2011-01-01T18:39:00.000-08:00

I finally had time to figure out how to send AT commands to the Digi Xbee radios. I've worked with them previously, but wasn't comfortable enough with how I was setting the radios. Now I've got them working the way I want.

Therefore, I will shortly be offering a robot terminal kit. It will permit you to communicate with a robot using your PC. I've got an example robot set up right now. It drives and turns as instructed while confirming the communications. The robot carries a simple arm and video transmitters that is also controlled over the radio. The robot is smart, it attempts to carry out your commands as best it can. Since the robot is using a ChapBot-14, it is a little limited - so eventually, I'll interface the radio with a CheapBot-18 on an articulated robot body and more complex arm. Moon rover anyone?

I'll also create a kit to allow BalloonSats to communicate with each other in order to create near space constellations.

GPS Simulator

2010-12-29T07:33:00.001-08:00

Work has started on a GPS simulator that will eventually become a NearSys kit. The simulator creates the GPS sentences that a near spacecraft will see on a typical mission. The ascent rate and burst altitude are all programmable. It's also possible to create a lose of satellite lock.

The GPS simulator will allow anyone with a programmable flight computer to test their flight code on the ground. It will also let anyone with an APRS tracker observe the behavior of their tracker without leaving the ground.

The simulation will reduce the risk of mission failure due to unforeseen behavior caused by high altitude GPS sentences. It also will let inidividuals run a test on their entire near spacecraft to observe that it will function as desired. Tests like this increase the number of successful near space missions.

Next up is the near space simulator, a totable thermal vacuum chamber called Near Space in a Can.

NearSpace Easy Flight Computer

2010-12-15T06:50:00.000-08:00

I've started testing on a new near space flight computer, the NearSpace Easy. It operates with a BASIC Stamp 2pe and shares the GPS data stream in parallel with a Tiny Trak 3. The Easy digitizes up to eight channels of analog data with a resolution of 12 bits. In addition, there are six digital ports and three servo ports.

A male DB-9 on the PCB is the GPS port. It provides power over pin 4 to the GPS as soon as it's plugged in. The GPS receivers NearSys will start selling are designed to interface to this flight computer (and the NearSpace UltraLight).

Connected by a wrapped cable is the flight computer's control panel. The panel mounts to the airframe of the near spacecraft to allow you to program both the flight computer and the APRS tracker, without having to open up the airframe. Also on the control panel are three power switches for the flight computer, servos, and audio beacon. Four indicator LEDs signal when the flight computer and servos have power, when the Tiny Trak has a GPS lock, and when the Tiny Trak is transmitting a position report. Finally, there is a mission commit pin that prevents the flight computer from recording data on the ground.

The NearSpace Easy can record up to 30 kb of data. In addition, USB jump drive adapters are sold for the BASIC Stamp that allow the storage of even greater amounts of data.

Not shown is the antenna. An antenna kit is part of the NearSpace Easy. It's a 2m dipole on the end of an RG-174 coax.

The NearSpace Easy is literally a plug and play near space flight computer. You'll need to select you battery (use a rechargeable lithium) and battery plug, but otherwise, just plug in the antenna and GPS and you're ready for a near space mission.

GPS Recievers - Real and Simulated

2010-12-08T07:02:00.000-08:00

NearSys is preparing to sell GPS reciever kits for use with its near space flight computers and BalloonSat Extreme. The GPS receiver is the UniTraQ GT-320 with high altitude firmware.

The kit will include mounting materials, project box, and DB-9 connector. The GPS is designed to draw power through its DB-9 connector, so plug it into a flight computer and it's ready to produce output, no extra batteries required.

NearSys is also testing a new version of its GPS simulator. This version 2.0 will become a kit and produces more GPS sentences than before. It's greater sentence output make it a better near space and rocket flight mimic. You'll download the program with your desired flight parameters set and plug it into the flight computer. It's two buttons allow you to control when the GPS has a lock (or loses a lock) and when the balloon launch begins. The LEDs indicate power, status of GPS lock, and ascent/descent. Mission elapsed time (MET) and altitude are optionally displayed on a PC or laptop running the PICAXE program editor.

NearSys Flight 10G

2010-11-04T06:55:00.000-07:00

The seventh flight of the year was launched Halooween morning form the Univeristy of Kansas. The mission as a practice for future KU flights next semester for the AE360 class, Introduction to Astronautics. The near spacecraft reaches an altitude of 98,500 feet according to the last GPS position report. Looking over the video, the near spacecraft made another 1,000 feet before the balloon burst, so it was closer to 99,000 feet. The flight was uneventful, until landing. The near spacecraft recovered in a tree too high for us to climb. It took three hours to get everything back. Next time, I'm bringing tree gear, like spikes and an expanding aluminum pole. Wings would be helpful, also.

Mission NearSys 10F

2010-10-17T14:47:00.000-07:00

The sixth mission of 2010 for NearSys (and 83rd overall) took place 16 October 2010. Launch was from Indian Hills elementary school at 9:00 AM. Present were meteorology and physics students from Washburn University. The physics club designed the BalloonSat carried on this mission. The flight reached an altitude of 88,469 feet and was observed bursting from the ground at our stop in east Lawrence. I put together a short video that includes this film clip of the burst.

The Washburn BalloonSat carried a flight computer, weather station, and camera. Here's one of the photographs they recorded.

Napier's Bones Part 2

2010-10-13T06:43:00.000-07:00

After seeing how students multiply multiple digit numbers by the lattice method, I was reminded of Napier’s Bones. John Napier (1550-1617) developed this tool for increasing the speed and accuracy of multiplications. His Napier’s Bones consisted of rectangular rods inside a board, or frame. On each rod, or bone, is written the multiplication of a single digit by 1, 2, 3, 4, 5, 6, 7, 8, and 9. Each number is written within a square divided by a diagonal line. Each tens digit is above the diagonal line and the ones digit is written below the diagonal line. The left side of the board is divided into squares marked with the digit 1 through 9. The squares on the side of the board are the same size as the squares on the bones. In fact, the fifth square on the left side of the board aligns with the fifth square in any bone. And that particular bone’s square has the value for five times the value of the bone. Since I have an interest in Baroque science, I decided to make my own set of bones.

This bone is for 9 and you can see it has written on it (starting from the top and working our way done) 9, 18, 27, 36, 45, 54, 63, 72, and 81. The best way to see how Napier ’s Bones are used is to work an example. So let’s multiply 25,806 by 79. You’ll need a sheet of paper and pencil to write the intermediate results.

First, load the bones for 25,806 into the board as shown below.

Now, we’ll first multiply 25,806 by 9 by reading off the sum of two digits in every diagonal formed by the numbers in the bones.

The product from multiplying 25,806 by 9 is read across the bones at the nine level of the board. Look on the left side of the board for the 9 and then start reading off numbers beginning on the right side and working your way to the left. First is the 4 all by itself in the lower right-hand corner. There is no other digit in its diagonal, so there is no other digit to add to 4, therefore just write a digit 4 on a sheet of paper.

Now move over to the next diagonal to the left, which contains 5 and 0 (0 is at its lower left of the 5). So add the 0 and the 5 to get 5. Write 5 to the left of the 4 you wrote first on the paper. You will have now written on your paper, 54

Now move over to the next diagonal to the left which contains the digits 0 and 2. Add these two digits together to get 2 and then write the digit 2 to the left of the 45 already written on the paper. You have 254 written on the paper now.

In the next diagonal as the digits 5 and 7. So add these two digits to get 12. Only write the 2 on the paper, the 1 (in the ten’s place) will be carried to the next diagonal. On your paper is now written 2254.

The next diagonal has the digits 4 and 8. Add those together and don’t forget to add the 1 carried from the previous diagonal. The result is 4 + 8 + 1, or 13. Again, only write the digit in the one’s place (a 2) on the paper (on the left side of the number you’ve written so far) and save the ten’s digit (a 1) so it can be carried to the next diagonal. The result on the paper so far is 32254.

The last diagonal is like the first diagonal in that there is only one digit. However, since the previous diagonal resulted in a carry, we’ll need to add that 1 to the 1 in this diagonal to get 2. Write 2 as the last digit on the paper. The result on the paper up to now is 232254. The number, 232,254 is the product of 25,805 X 9. Easy, wasn’t it?

In my next blog posting, we’ll add the product of 25,806 X 7. However, if you remember you multiplication, you know we’re going to write a 0 in the next line below the 232254 we’ve written so far and then add the digits for the product of 25,806 X 7.

Napier’s Bones Project

2010-10-12T06:30:00.000-07:00

NearSys UltraLight Flight Computer

2010-09-24T10:45:00.000-07:00

The first NearSys flight computer is now ready for purchase. The flight computer is programmed in BASIC and centered around the PICAXE-28X. The UltraLight has four analog channels, three digtal channels, two servo ports, and two camera ports. This means the UltraLight can record the analog values of four sensors, operate three digital devices including Geiger counters, control two servos, and operate two cameras. The flight computer has 32k of memory for storing mission data.

After building the UltraLight kit, you just ned to plug in a GPS receiver to be ready for flight. The flight computer contains a transmitter, TinyTrak based TNC, and a SMA antenna connector (the kit includes the cable and wire to make an antenna).

The UltraLight also includes a control panel that mounts to the near spacecraft airframe. The control panel permits the flight computer to be programmed without opening the airframe. The control panel has three power switches for main power, servo power, and audio beacon. The third switch powers up the audio beacon. the 90n dB piezo buzzer helps recovery crews locate the near spacecraft when it lands in tall grass of trees. Using a seperate battery pack for the servos insures that a bad servo can't ruin the science mission. The control panel also includes a Commit Pin that allows you to power up the near spacecraft long before launch without wasting memory recording data on the ground.

Additional information will appear on the NearSys website shortly (Nearsys.com/catalog).

Astrophotogaphy with a Digital Camera

2010-09-20T07:30:00.000-07:00

I've been using a FinePix S7000 to make astronomic images from Topeka. Most of my images are of Jupiter and its four major satellites for an astronomy/physics lab I'd like to write (I hope to create an activity book of astronomy with this and other lab exercises). Last night, after photographing Jupiter, I used my planetarium program to identify the satellites in the image. I found out that the planet Uranus was just above Jupiter and upon checking my image, i realize I recorded the planet.

The picture was five seconds long with a zoom of six power (optical zoom, not digital). I'll keep photographing the planets to monitor the motions between them and the fixed stars.

BalloonSat Extreme

2010-08-30T19:01:00.000-07:00

NearSys introduces the BalloonSat Extreme. This is one of the largest BalloonSat flight computers. At its heart is the BASIC Stamp 2 (the BS2pe is recommended), so it is powerful and easy to program.

The flight computer has an eight-channel analog port with 12-bits of resolution for sensors like weather stations. There is a five-channel digital port with connections directly to the BS2 for sensors like Geiger counters. Unlike other BalloonSat flight computers, the BalloonSat Extreme has a GPS Port to allow your BalloonSat to monitor and record GPS reports (like altitude and time). The flight computer can operate three cameras. The cameras can ones with modified shutter buttons or be Canon cameras running the CHDK USB remote program. The flight computer can also control three servos. The servos have a seperate power supply to prevent a bad servo from draining the main power supply.

Part of the BalloonSat Extreme kit is its Control Panel, a seperate printed circuit board. The Control Panel allows you to power up the flight computer without opening the BalloonSat. Two LEDs indicate power is available for the flight computer and the servos. Finally, there is a Commit Pin that allows the BalloonSat to be powered up long before launch. When ready for lift-off, pull the Commit Pin and the flight computer will begin recording data.

The entire kit is only $48. Check it out and its directions and sample code at, http://nearsys.com/catalog/balloonsat/extreme.htm

2010-06-13T14:09:00.000-07:00

I'v spent a couple of months perfecting a hovercraft-based robot. My initial goal was to develop a line of robots that behaved like satellites in a weightless environment. They would not move around on wheels (what good are wheels in space?) but navigate around on jets of air (safer than hot rocket exhaust). I discovered though, that air hockey tables can't generate sufficient air flow to lift the robot base. After another year and a half of thinking, I decided to use a hovercraft base in place of the air table. The design I came up with was made possible my resources on the Internet. The toy hovercraft described where just the thing to help me develop the NearSys HoverBot. Unlike traditional robots, the HoverBot accelerates when it drives. Most robots travel at a fixed speed that makes it easier to program navigation goals. The HoverBot roboticist must think about time, acceleration, velocity, and displacement when navigating. Here's an introductory video. You can learn more in my Servo magazine article and can soon purchase a kit from my website, NearSys.com/catalog.

The NearSys HoverBot

2010-06-13T12:32:00.000-07:00

I'v spent a couple of months perfecting a hovercraft-based robot. My initial goal was to develop a line of robots that behaved like satellites in a weightless environment. They would not move around on wheels (what good are wheels in space?) but navigate around on jets of air (safer than hot rocket exhaust). I discovered though, that air hockey tables can't generate sufficient air flow to lift the robot base.

After another year and a half of thinking, I decided to use a hovercraft base in place of the air table. The design I came up with was made possible my resources on the Internet. The toy hovercraft described where just the thing to help me develop the NearSys HoverBot.

Unlike traditional robots, the HoverBot accelerates when it drives. Most robots travel at a fixed speed that makes it easier to program navigation goals. The HoverBot roboticist must think about time, acceleration, velocity, and displacement when navigating.

Here's an introductory video. You can learn more in my Servo magazine article and can soon purchase a kit from my website, NearSys.com/catalog.

Test of Geiger Counters

2010-04-22T09:28:00.000-07:00

Last week I launched two geiger counters into near space. The mission was for KU aerospace engineering students and I got to send my experiments along in the tracking capsule.

The first geiger counter is the reliable Aware Electronics RM-60. I've flown this geiger counter dozens of times and really love it. It measures everything, alphas, betas, and gammas. Aware has a range of geiger counter products that you'll love. See them at http://www.aw-el.com/

The second geiger counter was built from a kit that's available from Electronics Goldmine. The tube is Russian built and does not include a mica window for alpha particles. Here's the webpage for this product. http://www.goldmine-elec-products.com/prodinfo.asp?number=c6979

The Russian tube is suppose to be pretty sensitive. In my tests, it detects more background radiation. However, I don't have a calibrated source that I can verify that it's actually detecting properly. I have s short video on a test that you can watch on my YouTube channel, www.youtube.com/nearsys.

Below is a chart I produced with data from NearSys-10A. Note how much more radiation the Goldmine geiger counter is detecting.

Normally the RM-60 shows a drop off at 62,000 feet. The driop off doesn't happen until closer to 70,000 feet and it doesn't show up well at all for the Goldmine detector.

So much more to learn!

HoverBot

2010-03-12T09:27:00.000-08:00

I finally got the Hoverbot set up with a relay H-Bridge. Unfortunately, one of the relays died. But that still gives me enough to demonstrate this proof of concept.

As you can see, the Hoverbot picks up quite a bit of speed when the drive fans are operating. In this video clip, the fans are on for three seconds and off for one. I've since reduced the lift fan's voltage to 4.5V (from 6V) and reduced the drive fans' voltages to 4.5 volts.

There are two problems to addess. The first is that the Hoverbot has a tendency to steer to the left. Experiments indicate it is due to the counter-clockwise spin of the lift fan. I may have to double up lift fans in a future design.

The second problem is that once the Hoverbot gets into a wobble, it won't come out. In fact, the drive fans are no longer effective in wobble. The HoverBot is going to have to detect this and correct it. Either an extendable foot or being able to shut down the lift fan is going to be required.

Enjoy the video

Clearing Misconceptions About Near Space Missions

2010-02-20T09:31:00.000-08:00

I was thinking about these topics earlier this week and thought they ought to be cleared up. So if you'll permit me.

Most people are familiar with the concept that motion is relative. This means that motion to one person looks just the opposite to another person who is not sharing that motion. It's all a matter of your frame of reference.

When we discuss things like the ascent rates and maximum altitudes of a balloon, we really should be discussing these issues in their more accurate frame of reference, that of the balloon. In reality, the balloon is holding still and the earth (along with the atmosphere which is firmly attached to the earth via gravity) is falling. Apparently this occurs because when we put helium into a balloon, we're removing it from the earth and its atmosphere (I'll refer to these as the earth-atmosphere system). When you remove low density material from the earth-atmosphere, you're increasing its average density. Recall that dense objects sink and less dense objects can float. The denser earth-atmosphere now wants to sink. And as long as the filled balloon is firmly attached to the earth's surface (via gravity), like by a person holding the balloon's load line or by tying the load line to a helium bottle, the balloon will hold up the earth. So those of you who are holding the filled balloon before launch, you're really holding the earth-atmosphere up. Think about that next time.

Once the balloon is no longer tied to the earth, the earth-atmosphere falls away. As the earth and its atmosphere fall away, the balloon is surrounded by less and less dense air. The balloon expands as a result. Since the helium is trapped inside the balloon, there are no further changes in the earth-atmosphere's density and it falls away at a constant rate that is dictated by the friction of the air around the balloon. The atmosphere, which remember is firmly attached to the earth, can only slide pass the balloon at a limited rate. Friction is why the earth does not fall away from the balloon infinitely fast. Many of you have no doubt noticed that at some where around 30-40,000 feet, the balloon appears (and let me stress appears) to rise faster. This is the result of the earth-atmosphere slipping around the balloon faster because of changes in air density and balloon size. This is pretty obvious if you recall that the force of friction is based on factors like surface area and density.

At the point where the atmospheric pressure around the balloon is low enough, the balloon bursts and releases its helium back into the atmosphere. This mixing of helium back into the earth-atmosphere system decreases its average density and let's the earth and atmosphere float back up to the balloon. The air rising around the balloon payload makes it tumble (due to turbulence) and inflates the parachute. The mixing of the balloon's helium with the atmosphere occurs very rapidly and therefore, the change in the density of the earth-atmosphere is very fast. This makes the earth-atmosphere begin to rise very quickly. At the earth-atmosphere rises back up to the balloon, the air becomes denser and the parachute creates more drag, slowing the ascent of the earth-atmosphere. Therefore, we see the initial ascent of the earth-atmosphere is very fast at the start, but over time, the ascent rate slows down until the balloon and earth make contact. At that point, the earth-atmosphere system and balloon are back in equilibrium and the motion comes to an end.

Now, since the days of the Greeks, we've known the world is round or spherical. There is no friction between the earth-atmosphere system and outer space. So when you go on a balloon chase, your car tires are pushing the earth and making it rotate the opposite direction. Let me stress, your car is NOT MOVING!! Therefore, it would help if everyone in their cars would travel together and go the same direction. If your chase teams will push the earth in the same direction, you'll rotate the earth in the same direction more quickly and get the earth rotated into the proper alignment with the balloon more efficiently. Therefore, it is imperative that we prevent chase crews from leaving their homes from the opposite direction, as this pushes the earth in another direction at the same time. When one big and heavy chase truck tries to push the earth to the west, the rest of our lighter cars trying to push the earth to the east suffer. I for one do not want to see my gas mileage decrease because of this. So please be polite to everyone else and follow along with the rest of the pack.

This also highlights the importance of using the balloon launch announcements system. There are some weekends with multiple balloon launches. If they are occurring at the same time, our cars are fighting each other to rotate the earth to our proper positions. So be considerate and coordinate your launches with other teams across the country.

Just doing my part to clear things up,
Paul

(Next time I'll explain the relativistic effects of a balloon launch and why the Twin Paradox makes use younger after each balloon flight)

H-Bridge Problem

2010-02-19T11:38:00.000-08:00

My HoverBot is grounded. The ducted fans that drive it require nearly 2A, but the TA78080K H-Bridges I'm using have built-in overload protection at 1A. I'd like to use H-Bridges so I can run the fans forwards and backwards. The TA8080's are lightweight and simple to use, so I really like them.

For an interim solution, I'll try using small relays. This won't give the Hoverbot turning ability, but at least it will test the concept until I can replace the H-Bridges.

Unit of the Einstein

2010-02-14T15:58:00.000-08:00

After watching Avatar, I started thinking about the ship (the Venture Star) and how it got to Alpha Centauri. The ship is suppose to use a matter-antimatter drive that is sub-light in speed. The crew was suspended for the six year flight. Assuming a constant speed (this means the acceleration to speed was pretty fast), it had to travel at 0.7 the speed of light (0.7c).

The relativistic effects of this a speed is calculated with the equation, sq-rt[1-(v/c)^2]. Plugging in the values I get,
sq-rt[1-(.7/1)^2]
sq-rt[1-0.7^2]
sq-rt[1-0.49]
sq-rt[.51]
0.71

This means
Time passed 71% as fast for the crew
The Venture Star contracted to 71% of its length (it acually gets little more complicated)
Mass of the Venture Star and crew increased by 1.4 times (1/0.71) at speed.

I propose we give the number 0.71 the unit of the Einstein. So the ship traveled at a speed of 0.7c and the crew experienced a relativistic effect of 0.71 E.

At the speed of light, photons experience 0.0E while we traveling at nearly no speed experience 1.0 Einsteins of relativistic effect.

Perhaps Es could be integrated to account for the time the ship spent accelerating to speed. If so, the crew experienced less than 0.71 E of integrated relativisitic effects (would the unit be labled Ei?). Their maximum would still be 0.71 E.

What do you think?

Small GM Tube

2010-02-07T13:01:00.000-08:00

I ordered the small glass GM tube from Electronics Goldmine (along with 2,000 T1 green LEDs that I will split with a sudent). A small tube like this can be powered by a transformer and 555 timer.

However, I wonder if there's a best frequency for the transformer and tube. Rather that adjust a pot on a 555, I'll use a PICAXE-08M to make the square ware. That gives the circuit a greater range of frequencies. Also, having some intelligence in the circuit will permit the tube to be shut down upon detection of a cosmic ray. Perhaps that will decrease its dead time. If that's not possible, then the PICAXE can produce a single pulse at detection and ignore the other pulses until after the tube's dead time. That will ensure a flight computer (which will monitor only the PICAXE and not the GM tube) will see a single pulse per detection (rather than the 5 or 6 it sees with the kit I've been testing).

Electronic Goldmine Geiger Counter

2010-02-03T11:43:00.000-08:00

I added enough hot glue to the terminals of the GM tube to put an end to the corona discharge. I also ran a test of the Aware Electronics RM-60 beside the Electronics Goldmine Geiger counter. The Goldmine detector picked up six times as much radiation.

Here's what the current detector looks like.

Electronic Goldmine Geiger Counter Kit

2010-02-01T12:57:00.001-08:00

As Mike Manes of EOSS suggested, I ran the geiger counter in a vacuum to make sure it didn't arc over. The tube has 600 volts across it, so this is an issue in low air pressure conditions. At first it looked fine. Then at 28 inches of mercury vacuum (about 94% vacuum), the LED indicator remained on. Some where the 600 volts was finding a ground and triggering the LED. I started coating the circuit in hot glue and have it running at lower pressures, but stil not in a full vacuum. I ran out of hot glue to do any more work, so I'll work again in this tomorrow.

Geiger Counter kit for Near Space

2010-01-30T09:30:00.000-08:00

I've started my experiments with the Electronics Goldmine geiger counter kit (C6979). The kit was on special for $70 (down by $10). It operates from a nine volt battery and uses a 555 timer and transformer to boost the voltage to 600 volts. The 555 timer operates at 128 Hz. So when there's a detection of a cosmic ray, there are six (some times five) pulses during the GM tube's dead time.

Gas molecules inside a GM tube become ionized at the passage of a subatomic particle. The ionized gas lets electrons, pushed by the high voltage on the tube, pass from the wall of the GM tube to the center conductor. This makes the GM tube act like a switch at the passage of a cosmic ray. While the tube remains ionized, it's unable to detect other radiation events. How quickly the GM tube clears out this ionization is called the tube's dead time. The shorter the dead time, the more frequently the tube can detect radiation. In near space, I have detected up to 800 counts per minute. On average then, there is 75 milliseconds between detections. As long as the GM tube's dead time is less than that, it should accurately detect radiation levels in near space.

I'd like to try placing a capacitor across the GM tube to smooth out the voltage spikes. If that works, then the flight computer doesn't have to divide the number of counts by six to get the real radiation levels. Perhaps it will also let the tube clear out faster (reducing its dead time).

It's a short video about my experiments to date. Look for an article in Nuts and Volts this year.

Onwards and Upwards,

Your Near Space Guide

HoverBot Video

2010-01-29T23:51:00.000-08:00

I've continued my experiments with designing small hovercraft. The video is short, but it shows I'm about ready to add a robot controller to a hovercraft. Balance is going to be a big issue. The lift fan is going to need lithium batteries, since they draw so much current.

Here's the YouTube link
http://www.youtube.com/watch?v=_ju40nRB_eE

Hover-Bot

2010-01-29T07:36:00.000-08:00

I'm working on the base of a Hover-Bot. It's in the design stages, so only the lift factor has been checked. I have two more ducted fans on order and they'll supply the propulsive force for the Hover-Bot. My goal is to create a two dimensional simulation of satellites.

In traditional robots, when the motors are shut off, the robot stops. Not so for a "nearly" frictionless sliding robot. To get the Hover-Bot to stop, it must apply reverse thrust to counteract the initial thrust that got it moving. There's also the issue of sliding sideways.

Currently I'm investigating the amount of current the lift fan draws based on the supply voltage.

I have a movie clip that I'll post shortly.

CheapBot Single Axis Arm

2010-01-23T07:11:00.000-08:00

Here's the demonstration of the new single axis robotic arm I developed. It's a simple deign that's suitable for entry level robotics competitions. In this case, the CheapBot robot is combining a line follower, beacon detector, and robotic arm to carry plastic balls from a pick up point (which is marked by an IR beacon) and carries them to a destination. Both the pick up point and the destination are marked with black tape. A robot in a game like this would score points based on the number of balls it delievered in a fixed period of time. In the case of a tie, the smaller progam (in bytes) wins.

2010-01-20T11:41:00.000-08:00

I'm developing a simple robotic arm for 4H competition. The arm is single axis (it rasies and lowers) and is capable of carrying and dropping a lightweight plastic ball. Currently, this robotics testbed seeks the black line at the end of the game arena and raises its arm. To tell you it's ready for a ball, it beeps - and gives you three seconds to load it. Afterwards, it turns and drives for a few seconds before lowering the arm and dropping off the ball.

The next update will have the robot drive back and forth between two black lines, picking up and delievering balls. Instead of waiting three seconds for you to load a ball, I'll add a switch to the arm so the robot can tell when one has been loaded.

I'm still trying to prefect my IR beacon. I want the robot to determine which end of the arena is the pick up point because of the beacon above it.

US Geek Shortage

2010-01-17T12:45:00.000-08:00

Here's an interesting article.

www.wired.com/dangerroom/2010/01/darpa-us-geek-shortage-is-a-national-security-risk/

We need to be teaching and encouraging more kids to take science,math,and engineering classes. Is there a US FIRST club at your local high school? They could always use some help.

Robotic Arm Redux

2009-12-14T13:00:00.000-08:00

I made another modification to the robotic arm. First, to make sure a jack will trigger the lever switch, I covered the end of the arm with neoprene foam. That makes it more likely the robot will detect jacks when they are picked up off-center.

I saw a problem were the arm successfully picked up a jack, but then dropped it after rasing the arm. I'm going to need to add a line of code to the robot to check the switch at the end of the arm one more time after the arm is brought up. I only have three bytes of memory left, I hope I can shoehorn that in.

CheapBot Robotic Arm

2009-12-13T11:56:00.000-08:00

I've started testing a robotic arm for my line of CheapBot robots. It's easy to make an arm raise and lower, but I've had difficulty designing an end effector for it. It has to be light weight and reliable. After reading about the wire snare used on the Space Shuttle robotic arm, I decided to give it a try for the CheapBot robotic arm. The arm prototype is attached to my CheapBot test bed in the image below.

You can see a lever switch attached to the nose of the arm. That's so the robot can detect that it has picked up an object

In the snare test video above, you can see the piano wire snare extend, the arm drop, the snare retract, and the arm raise with the toy jack.

Look for one or more arm kits (I'm working on a second design), a radio, and smart beacon kit early next year.

May all your holidays be robotic.

Squeak eToys

2009-12-09T10:54:00.000-08:00

Squeak will be one of the installed applications for the One Laptop per Child program (http://laptop.org/en/). It's a neat application and a good way for kids to show what they have learned (it would go great in combination with a Power Point).

I just completed my CheapBot Squeak program for my Constructivist Philosophy class and will post the final program on my webpage (NearSys.com) under the catalog link this weekend. It's a work in progress and over the months, I hope to include programs that simulate more features of the CheapBot and even create simulations of a near space mission.

ARHAB Email Traffic

2009-11-23T09:54:00.000-08:00

I've been looking into email traffic for ARHAB groups on Yahoo. I created the following chart in the hopes that I'd see email traffic increase for GPSL meetings. It looks like a weak correlation, but something is there. Next to apply some statistics, rather than rely just on looks.

Squeak eToys

2009-11-10T09:58:00.000-08:00

My CT 871 class has me writing programs using eToys. It's a menu driven programming language and is pretty good at letting help kids write applications that demonstrate what they know. Kids can write games or simulate physcial systems, like orbiting planet or bouncing balls.

For my final project, I'm writing a simulator for the CheapBots. The simulator lets a person control the H-Bridges of the robot in order to drive it around. In other words, the user acts like the robot controller. Future abilities of the program will let users observe the responses of the CheapBot Line Follower as the robot drives around.

The software is free at www.squeakland.org

Near Space Horizon

2009-10-31T09:27:00.000-07:00

(Click on image to see a larger image)

This is my first attempt to limb sound from near space. These images were taken every 10,000 feet and stitched together. I tried to select the best, where the camera was pointed in the same direction. As you can see, they don't all line up properly, but it is a start.

In the future, I'll fly a sun sensor to let the flight computer align the camera properly. I also need to calibrate the field of view of the camera so the horizons can be properly aligned in the images (the horizon is depressed in near space - my photo montage assumes the horizon is not).

I'll put an article together for Nuts and Volts on this line of work. I assume it will be useful for detecting haze layers, including volcanic ash, in the future.

CheapBot Radio Antenna

2009-10-28T09:55:00.000-07:00

Today I'm planning to solder the antenna for the ChepaBot radio controller. I purchases a SMA to SMA extension cable from Jameco for this. I'll cut the coax cable in half, peel back the inner conductor adn outer jacket, and solder wires to them.

The radios opewrate at a frequency of 434 MHz. If I take that frequency and divide it into 486, I get the proper length of the antenna (which will be a dipole). That comes out to 1.078 feet, or 12.936 inches. Divided in half and I get each element should be 6.5" long.

You can find an antenna calculator at http://www.crompton.com/wa3dsp/hamradio/antcalc.html

RC for Robots

2009-10-26T10:55:00.001-07:00

I'm soldering a test board for a robot radio. To use it, you program a robot to respond to one of eight messages sent by the hand controller. The robot has its own radio and will reply back to the messages you send it. The handheld controller will have an LCD so human readable messages can be displayed.

The hand controller communicates with your robot like we communicate with rovers on Mars. Messages sent to the rover are acted upon, but intelligently, not as an automatic reponse like an RC car. That way, if you send a message to drive off a cliff, the robot can analyze your message and refuse to comply. Not only will it refuse, it will also send a message back about why it isn't complying.

Robotic Arm

2009-10-22T05:40:00.000-07:00

I'm working on a simple robotic arm design for the CheapBot robots. It uses two servos, one to lift the arm and the second to pul a wire lasso tighter. The wired lasso is made from piano wire, so it naturally wants to spring open when the smaller servo extends the wires. Both ends of the wire lasso attach to the servo horn, so when it moves the ends of the wires one inch, the lasso expands by two inches.

I want to try a thinner wire. To make it simple to use, the lasso must be really flexible to wrap around the target regardless of how sloppy the positioning between the arm and the target is. The wire lasso also keeps the end of the arm very light, an important issue when you have a six inch long arm (you can build up a lot of torque for the servo to lift).

Rubber stoppers take out some of the slop in holding the target. I need to find a lighter weight "cushion" for this purpose and an easy way to mount it. I'll look into a foam rubber shirt for the end of the arm as a replacement.

I'll post some pictures soon.

NearSys 09G and H

2009-10-20T09:51:00.000-07:00

Here are some images taken on last Saturday's mission.

This one was taken shortly after balloon burst. From around 80,000 feet, we're looking at the cloud cover over Melvern(?) Lake.

We're getting closer.....

Webpage Updates

2009-10-19T09:40:00.000-07:00

I've started posting updates from the last near space mission. I'll massage some of the student Balloonsat data, but want to let them work their data over before I post the results.

Since it was two flights, there are two webpages for the results.

http://nearsys.com/arhab/flightdata/2009/g/index.htm
and
http://nearsys.com/arhab/flightdata/2009/h/index.htm

The only bad thing to happen was nylon zip ties failing and dropping one of the trackers (it's battery was dead by then). So it looks like I'll start some testing of zip ties in cold temperatures to see what I can learn from the experience.

The Ft. Collins Balloon Story

2009-10-18T12:23:00.000-07:00

I helped launch two weather balloons this weekend. They were for Univeristy of Kansas and Kansas Wesylan University students. Some of these students will become science teachers and because of this experience, they will launch BalloonSats for their students.

However, after listening to the Balloon Boy story out of Fort Collins, I can't help but wonder if this is going to impact amateur near space exploration. All it takes is for one irresponsible person to negatively change public perceptions of amateur science in general and near space ballooning in particular. If as a result, access to near space ballooning is stopped or limited, students who's only dream is to launch experiments into space will be denied the opportunity of reaching this dream by taking their first step into near space.

Gawker is carrying an expose on Mr. Heene from a former friend and it doesn't cast a favorable light on him. I can understand Mr. Heene's concern if the balloon got away from him and he wanted to get it back. That however, does not excuse reporting that his son was onboard as a way to get state and federal government to track it. Claiming your son is onboard also reflects a lack of forethought. What are you going to say once the balloon is recovered (and it will) and its discovered no one was onboard?

I hope the public realizes Mr. Heene is not the face near space exploration.

Tracking

2009-10-16T09:52:00.000-07:00

Last chase I used a D7 and Garmin GPS V. They sat on the dash and did a lot of dancing around during the chase. Today my students are helping me make a dash-mounted platform to hold the radio and GPS. They are mounted so I can read the displays from both devices, but it would be better to have a navigator go along to read.

The system is simple and starts up as soon as you apply power. That means no waiting to boot a PC or load software.

NearSys 09F

2009-10-15T06:02:00.000-07:00

We may be launching two near space missions this week. The flights are for the University of Kansas, School of Education and Kansas Wesylan Univeristy. The person who made this all possible is Pete Sias, the man who got me started in near space exploration 15 years ago.

The launch takes place Saturday at 8 AM from trhe KWU campus. You should be able to track the flight at one of this webpages.

map.findu.com/kd4sth-4
map.findu.com/kd4sth-8
map.findu.com/kd4sth-9

Onboard will be five KU BalloonSats and at least one experiment from the KWU Physics club.

I'll be flying the reuseable lunch bag tracker I'm developing for Popular Mechanics, an old backup tracker, and a module with a new flight computer. This module carries most of the science. It will measure cosmic rays, weather conditions, internal temperature, and several cameras, including still and video.

CheapBot MagArm

2009-10-09T10:07:00.000-07:00

Using DALPro presensitized copper clad and ARES Lite, I created the magnetic robotic arm for my line of cheapBot robots. I used a Dremel drill and its drill stand to drill out the board. The PCB still has to be populated and I hope to do that this weekend. A reed relay (and anti-kick back diode) powers the electromagnet. The PCB has drilled holes for mounting the arm to a servo. The servo allows the arm to be raised and lowered. The lifting servo and arm can be mounted to a second servo to allow the arm to rotate. But for beginners, I recommend using the robot to rotate the arm instead.

The CheapBot MagArm will allow robots to pick up slightly modified ping pong balls. This gives students the challenge of programming the robot to pick up stuff without spending more time trying to make the system work mechanically.

Smart Proximity Detector

2009-10-08T09:19:00.000-07:00

The Smart Proximity Detector I have developed uses a PICAXE-08M to control the blinking of two IREDs. The detector mounted in the middle of the PCB determines if there is a reflection from the IREDs. Since the PICAXE controls when and how fast each IRED blinks, it knows what condition created the reflection. The detector is most sensitive to 38 kHz IR and gradually gets less sensitive as the frequency gets off center. This gives the PICAXE a way to "estimate" a distance to the reflecting object and if it is located across the robot, or just on one side or the other. Not only can an object be detected across the robot, but if there is significant difference in the distance on the left and right side, that can also be determined.

The boards tested fine, so look for kits on Nearsys.com/catalog shortly.

Magnetic Robot Arm

2009-10-07T11:45:00.001-07:00

Last night I came up with a solution for a lightweight, but inexpensive robot arm for CheapBots. The arm is 0.6 inches wide and 5 inches long. Its grasper will be switched for an electromagnet. A relay will control the current for the magnet since the robot controller cannot provide that level of current. The arm will be light enough that a small servo can raise and lower it. The servo and arm will be turned on side, but a second servo could be mounted below to allow the arm to rotate about the horizontal plain.

I'm looking into hall effect sensors now as a way for the robot to detect the presence of a magnetic field. That should help the robot align its arm, because the objects it will pick up will be ping pong balls with small neo magnets glued inside (the bottom of the ball will have a cut hole so it doesn't roll).

Perhaps I can shoot the PCB for the arm tomorrow.

NearSys 09F Winds Aloft

2009-10-06T06:10:00.000-07:00

This chart was developed from APRS data (positionn reports) transmitted by the near spacecraft. As you can see, the winds aloft were preetty strong and the thickness of the high speed winds was pretty large. No wonder it recovered 112 miles away!

NearSys 09F

2009-10-05T11:44:00.000-07:00

Here are a couple of images from my last mission.

The balloon has burst and we're parachuting back to earth.

This is on ascent. The near spacecraft has just broken through the clouds.

NearSys 09F

2009-10-04T18:47:00.000-07:00

NearSys 09F reached an altitude of 79,414 feet. It recovered 112 miles away, further than we were planning. That's because the jet stream was much faster than expected. That along with the traffic jam near the end of the turnpike made for a slightly frustrating recovery. Once we got everyone together, we drove to the last know location (4,000 feet AGL) and figured the near spacecraft drifted another 1/2 mile. Once we got close, we began picking up packets again.

The tracking modules based on the MicroTrak 300's had trouble getting packets to us during the chase. However, the APRS gateways put plenty of packets on the Internet. Um, this calls for some investigation. If you know of someone who can help me analyze the radiation pattern and strength of the transmitter, please let me know.

I'll post more information on Washburn's first near space flight in the next few days. There will be a full report on my website.

Washburn University Launch

2009-10-02T09:46:00.000-07:00

This Saturday I'm helping Washburn launch their first near space mission. Since I completed the tracker for my Popular Mechanics article, I'm going to send it up for a real test. I'll add an additional two trackers as backup. I believe in using two trackers, in case one fails and since this will be the first flight of the Pop Mech tracker, I'm sending the two trackers as back up for it.

The three trackers are transmitting as KD4STH-4, -8, and -9. The frequency for all three is 144.390.

In addition, this mission will carry the thermopile telescope I designed. It also has a weather station like the kind I'm selling, two video cameras (one pointed up and the other pointed down), digital still camera recording horizontal pictures every 15 seconds, and an accelerometer.

I'm looking forward to a fun flight. If you're in the area, come on out.

Fisheye Photo

2009-09-30T09:32:00.000-07:00

Here's an image!! The University of Nevada, Reno did a near space launch this week. Onboard their near spacecraft was a camera with a fisheye lens pointed down. Check their Flickr site for this impressive image.

http://www.flickr.com/photos/40137058@N07/3963101620/

Smart Proximity Detector

2009-09-29T05:53:00.000-07:00

The PCBs I've designed for the Smart Proximity Detector are int eh mail. I expect them this week. The detector uses a PICAXE-08M to operate IREDs and a 28 kHz detector.

I'm starting to pack kits. I began by creating a spreadsheet with a list of the parts and costs. After that, I'll copy the list of parts into a word document and print that out. I follow what's int he document to pack the bag with parts. I also write the number of items that goes into each bag. That way, after I collect the parts on the list, I do a final count before packing them into their bag. However, before packing each bag, I now affix a label on the outside of the bag with teh name of the kit.

The bag for the prox detector is a sandwich bag, since the PCB is six inches wide.

The Smart Proximity Detector is for any robot that can receive serial data. Look for it under Catalog at the NearSys.com website shortly. I have a video demonstration of a robot using the detector that I am completing. That video along with directions and a copy of the code will be available online for free.

NearSpace UltraLight

2009-09-26T15:10:00.000-07:00

I had a request for the NearSpace UltraLight flight computer. I've started soldering parts together for the board, but haven't completed it yet (or tested).

The flight computer is like a BalloonSat Easy with a built in radio and GPS Port. After building one, you just need to attach the antenna, batteries, and GPS receiver and you're ready to fly. The final kit will include memory (which the version 2.0 BalloonSat Easy doesn't) and a coax cable and wire for making the antenna. It will be my most expensive kit since it includes the $60 radio transmitter. But overall, it should be one of the least expensive ways to ow a flight computer suitable for near space missions.

One day, I hope to enter into the model rocetry field with a line of model satellite payloads.

Tuning a IR Beacon

2009-09-25T11:26:00.000-07:00

I've developed a 38 kHz IR beacon for the CheapBot-08. It uses a 556 timer IC to create and combine two square waves. Half the 556 generates a 38 kHz square wave and must be adjusted for the proper frequency (this accounts for the tolerances in the resistors and cap). The second half of the 556 generates a roughly 10 Hz square wave. Combined, the output is a 10 hZ square wave of the 38 kHz beacon. Shutting off the 38 kHz beacon every 0.1 seconds prevents the robot's 38 kHz detector from losing senstitivity to 38 kHz.

I thought I'd just put the 556 on the o'scope in class and tune it up (adjust thwe PCB's pot to get the proper 38 kHz pulse). But I had forgotten that the o'scope would trigger on any signal, whether it was from the 10 hZ of the 38 kHz square wave.

I finally tapped into pin 5 of the 556 to see just the 38 kHz signal. It looks like on the next design, I'll add a test point to the PCB to make tuning the 38 kHz side easier.

BalloonSat Kits

2009-09-24T12:21:00.000-07:00

I think I'd like to start a line of BalloonSat kits. This would be for the airframe and not just the flight computer. A kit would consist of seven sheets of Cellfoam 88, dowels, 1/4-20 nylon bolt, washers, black marker, tubes, plastic sheet, space blanket, and some tape. There would be enough material to make an airframe large enough to hold a video camera, flight computer, and and experiments.

This means I need to get the book together (see my Citizen Scientist articles) for directions and recommendations. The book I plan to publish through Create Space. However, I'll need an ediotor to read over the book first.

Now if there was a way to make a camera kit.

CheapBot-08 Radio Slave

2009-09-23T12:51:00.000-07:00

Since the PICAXE-08M has such little capability for a robot, I'm incorporating a second into a robot to handle the radio communications. Using a serial port basically converts the two I/O ports required for the radios into one. Now to figure out the two way communication protocol between the nmaster and the slave.

Find Me Spot

2009-09-21T07:32:00.000-07:00

Find Me Spot is a GPS tracking system that communicates position reports through a satellite. If you attended GPSL 2008, you'll be familiar with this tracker, as Bill Brown gave a presentation on it. Bill is doing the coolest stuff, you should get to know him.

With all the talk about the MIT flight that used a cell phone for tracking, I'm wondering about writing an article on using Find Me Spot to track. This would allow someone who does not have an amateur radio license to launch near spacecraft. Of course, the tracking unit would have to go up as a back pack with a Tickle Me Elmo to create a Find Me Elmo.

CheapBot-08

2009-09-20T06:51:00.001-07:00

The smallest, simpliest robot controller I have created is based on the PICAXE-08M. With only five I/O pins, it's a tough one to build a robot controller around. Of those those five I/o pins, only three are truely I/O. One is an input only and the other is only an output.

Problem number one was the H-Bridges. With a code space of only 256 bytes, it was important to incorporate two H-Bridges into the design. That way it only takes two short lines of code to drive or steer the robot and the PICAXE could do other tasks simultaneously. But it takes four I/O pins to operate two H-Bridges. What could a robot controller do with one I/O pin?

My solution was to double-up the function of one of the I/O pins. It controls the drive of two motors and therefore leaves the robot controller with two I/O free pins. So now the robot can walk and chew gum at the same time. However, it can't pivot about its center - it has to turn centered on one wheel.

The turning subroutine has the robot taking turns pivoting on the left and right wheels. I call it psuedo-zero turn radius. Since it takes so little memory to turn the robot, the extra code space required doesn't fully offset the gains in the extra I/O.

Electronic Supplies

2009-09-19T13:23:00.000-07:00

What we need around here is an electronics supplier. I ran out of parts filling an order and had to order them online last night. Wouldn't be nice if enough people did hobby electronics to justify stores (like the old Radio Shack) carrying parts again.

It's up to small businesses like NearSys to specialize in types of electronics that hobbyists might like to purchase.

Do we have a problem in the US that not enough people are doing hobbies?

Smart Proximity Detector Movie

2009-09-18T12:08:00.000-07:00

This weekend I plan to begin editing a movie on my Smart Proximity Detector. The detector is programmed to send range information from its left and right side sensors. The robot in the movie (a CheapBot-14 controller on a CheapBot body) is programmed to drive away from the nearest obstacle. It's fun to watch the robot steer away from the plastic wall I swing in front of it.

GPS Simulator, Part 2

2009-09-17T09:57:00.000-07:00

The GPS Simulator only creates GPGGA sentences. That's because the memory in the PICAXE-08M is limited to 256 bytes. And it was tough to cram that much into that limited amount of space. Eventually I'll get around to creating a simulator that produces all the GPS sentences in a way that looks like a near spacecraft on a mission. That's the one I'd like to produce as a kit.

GPS Simulator

2009-09-16T11:52:00.001-07:00

I've been building new GPS Simulators for a customer in Texas. The simulator uses a PICAXE-08M to send sentences that look like the GPGGA sentences of a balloon in flight. Eventually I'll move this to a larger micro and have it simulator all the sentences of a GPS receiver on a balloon flight. Using the simulator lets you test a flight computer's program on the ground.

A ground test like this lets you find errors without leaving the ground (where it's a lot cheaper to correct).

Line Follower and the Creation movie

2009-09-15T19:43:00.000-07:00

I've updated my online catalog with a movie about the CheapBot line follower. It's a four inch wide PCB with two pairs of IR LEDs (IREDs) and phototransistors. The IREDs constantly emit IR. If the neighboring phototransistor detects a reflection, then the surface below the pair is white. No reflection detection means there's a black strip below that side of the robot and corrective action is necessary.

The phototransistor and its collector resistor behaves like a voltage divider. In the non-conducting state, conventional current flows from the positive supply, throught the resistor, and to the robot's I/O port. This means a positive five volts is detected by the robot controller (AKA a logic high). When the phototransistor is conducting, current from the collector resistor flows through the phototransistor to ground. This leaves no current (or more accurately, very little current) to flow to the robot controller. As a result, the controller see less than 1.4 volts, or a logic low.

I read earlier today that the movie, Creation, which is about Charles Darwin, can't get an American company to distribute it. Amazing, we live in the 21st century, but some throw-backs are going to make it too contraversal to show a movie about Darwin's most important contribution to science.

Thermal Test Results

2009-09-14T05:49:00.000-07:00

After about a 45 minutes test, the interior of the lunch sack was 50* F warmer than the chamber's air temperature (-10 vs -60). And this was with one sheet of foam rubber missing and no power applied to the tracker. I did notice the antenna elements did get stiff. But they are silicon jacketed 14 gauge stranded wire, so it should be just fine.

I need to look up some information on Rocketman parachutes to finish this article for Popular Mechanics online.

Thermal Testing

2009-09-13T12:20:00.000-07:00

The movie 9 wasn't that great, but it's animation was. The story had promise, however.

I built a thermal test chamber years ago that circulates cold air around a test subject with air fans. Dry ice is loaded into a metal in basket and then two smaller in baskets sit on top of the dry ice. The experiment sits on top the stacked baskets allowing cold air to flow around the experiment.

Right now the Popular Mechanics near space tracker is inside. I plan to let it chill for 30 minutes (at least) and compre the internal temperature of the reusable lunch sack to the outside air temperature. The dataloggers for this test are Hobos.

Popular Mechanics Tracker

2009-09-12T10:11:00.000-07:00

Thanks to help from VHS Products, I have a current version of the MicroTraker 300 to use for my Popular Mechanics article. I was using their version 1.3 initially, but having trouble with it.

The Pop Mech article I'm writing explains how to build a near space tracker inside of a reuseable lunch sack. This is similar to designs by NSTAR and TVNSP. The goal is to keep it cheap, but leave room for expansion and flexibility.

This afternoon I'll watch the movie 9. It takes place in a post-human world were humans are destroyed by their technology. Ummm, should I be building robots?

CheapBot Beacon

2009-09-11T09:48:00.000-07:00

I've started designing a smart beacon for robots. The beacon will flash one of four signitures in IR based on the setting of a jumper. It uses a PICAXE-08 that will measure the voltage generated by the jumper setting. The jumper portion of the circuit consists of four resistors in series to make a voltage divider. So a jumper setting creates either 1.25, 2.5, 3.75, or 5 volts for the PICAXE -ADC. When the PICAXE powers up, it will measure the ADC input voltage.

Now the PICAXE can't send enough current to all the IR LEDs (IREDs). So it triggers a transistor when then provides the power for the IREDs. A chromed ball above the IREDs (which are pointed inwards and up) will fan the IR out in all directions.

After completing this design, I'll build a PCB for a IR beacon detector that robots can use to locate beacons.

A beacon placed on a robot locates the robot. But a beacon can also be placed on a destination for the robot to find.

Smart Proximity Detector

2009-09-10T10:42:00.001-07:00

A PICAXE-08M operates the proximity detector. It takes turns flashing two IR LEDs (IREDs) at six different frequencies. The detector between the pair of IREDs is most sensitive to 40 kHz flashes. So when the IREDs are flashed at a different frequency, its ability to detect reflections is reduced (it can't see obstacles as far away). So the PICAXE flashes an IRED and checks with the detector to see if it saw the reflection.

The PICAXE cycles through all six frequencies until there are detections on both the left and right IREDs (the only time it runs through all six frequencies is if the IR detector doesn't ever detect a reflection). The PICAXE then sends a serial message with the range to the obstacles as thety appeared to the left and right IREDs. The range of dfistance is from 1 to 6, with a value of 7 indicating there was no reflection or that the obstacles are infinity far away.

The robot reads the data from the proximity detector as it needs to and then acts on the results.

Here's the code as it is currently written.

symbol RightDetect = B0
symbol LeftDetect = B1
symbol distance = B2
symbol counter = B3
symbol RightDistance = B4
symbol LeftDistance = B5
symbol left = 1
symbol right = 4

Proximity_Detect:
RightDistance = 7
LeftDistance = 7
for counter = 1 to 6

CheckRight:
if RightDistance < 7 then CheckLeft
low right
high left
gosub Flash
RightDetect = pin3 '0 = detect, 1 = no detect
pwmout 2 off
pause 2
if RightDetect = 1 then CheckLeft
RightDistance = counter

CheckLeft:
if LeftDistance < 7 then FinishCheck
low left
high right
gosub Flash
LeftDetect = pin3 '0 = detect, 1 = no detect
pwmout 2 off
pause 2
if LeftDetect = 1 then FinishCheck
LeftDistance = counter

FinishCheck:
if LeftDistance < 7 then IsRight7
goto Repeat_Flash

IsRight7:
if RightDistance < 7 then Report

Repeat_Flash:
next

Report:
serout 0,T1200_4,(255,"L",LeftDistance,"R",RightDistance)
goto Proximity_Detect

Flash:
if counter > 1 then Check45
gosub kHz46
goto End_Flash

Check45:
if counter > 2 then Check44
gosub kHz45
goto End_Flash

Check44:
if counter > 3 then Check43
gosub kHz44
goto End_Flash

Check43:
if counter > 4 then Check42
gosub kHz43
goto End_Flash

Check42:
if counter > 5 then Check41
gosub kHz42
goto End_Flash

Check41:
if counter > 6 then Check40
gosub kHz41
goto End_Flash

Check40:
gosub kHz40
End_Flash: return

kHz40:
pwmout 2,24,50 ' 14 inches
return

kHz41:
pwmout 2,23,49 ' 10 inches
return

kHz42:
pwmout 2,23,48 ' 9 inches
return

kHz43:
pwmout 2,22,47 ' 6 inches
return

kHz44:
pwmout 2,22,45 ' 5 inches
return

kHz45:
pwmout 2,21,44 ' 3 inches
return

kHz46:
pwmout 2,21,43 ' 2 inches
return

Proximity Detector

2009-09-09T10:13:00.001-07:00

I've developed a smart proximity detector for robotics. A PICAXE-08M flashes two IR LEDs at 40 kHz (one at a time). The 40 kHz IR detector between the IREDs determines if there is a reflection from the IREDs. The PICAXE monitors the output from the detector. Since it knows when it flashed each of the IREDs, it knows which of the IREDs caused the reflection. The IREDs are mounted on the extreme left and right sides of thePCB giving the smart proximity detector the ability to determine if a wall is located on the left side, right side, or across the front of the detector.

Eventually I'll flash the IREDs at different frequencies to determine if the wall is located farther away or closer.

but first, I have to set my wait period between left and right flashes. I don't know how long the detector "remembers" that it saw a reflection.

Easy Star Gazing

2009-09-07T11:37:00.001-07:00

One of my hobbies is astronomy. Currently I'm giving introductary astronomy lessons quarterly at two public libraries. My latest presentation is available online at nearsys.com/easy/. There you will find a Power Point and supporting handouts.

BalloonSat Launch

2009-09-05T19:41:00.000-07:00

I have a near space launch scheduled for September 26th. This will take place in Salina, KS with the help of Pete Sias, the guy who got me started in near space. The launch will carry five BalloonSats my CT442 class is assemblying. I also hope to carry the lunch sack tracking module I'm developing for my Pop Mechanics article.

LabPro UVA and UVB

2009-09-03T09:49:00.001-07:00

Two of the LabPro sensors I'm nmost interested in seeing operate are the UV sensors. They're mounted inside a thin tube, so I suspect they're direction sensitive. I'll recommend my students mount them inside a ping pong ball (acts as a diffuser) and point them up through the top of the BalloonSat.

LabPro Dataloggers

2009-09-02T11:57:00.000-07:00

The latest datalogger I'm playing with is the LabPro by Vernier (http://www.vernier.com/). The logger/programmer is smart, it detects the sensors plugged into it. After collecting data, the programmer then processes the data appropriately for the sensor and displays the results in a chart. You can export your data into a text file for processing in a spreadsheet. That's great for incorporating GPS data. I'll post my notes on using the datalogger on my website alogn with some pictures on making a LabPro BalloonSat.

Vernier is popular in science classrooms.

Calculating Distance to the Horizon

2009-09-01T11:56:00.000-07:00

You can calculate the distance to the horizon with a simple equation. The real equation involves trig, but this one gives a nearly identical answer.

Dist(in miles) = sqrt[height(in feet) X 1.5]

Multiple the altitude in feet by 1.5. Then take the square root of the answer. The distance to the horizon is in miles.

Since my eyes are 6 feet above the ground, I multiply 6 by 1.5 to get 9. The square root of 9 is 3. So the distance to the horizon for my eyes is three miles.

A near sapcecraft at 90,000 feet sees 367 miles to the horizon. Because of refraction, radio should reach a little bit further.

St. Louis Arch

2009-08-31T09:42:00.000-07:00

The arch in St. Louis is welded stainless steel. I took this photo of it after my trip to the top. The ride to the top is inside a space age capsule that holds five. At 630 feet tall, I calculate I could see 30 miles to the horizon.

DALPro

2009-08-29T18:41:00.000-07:00

DALPro is a physicaly small shop, but they sell around the world. The original company was called Kepro, after the owner. They went out of business in 2004 and D and L took over. A Kepro board was used onboard the first space shuttle launch. I'll have to find out where. It's it amazing that the PCB materials you can purchase today for your projects was good enough for a manned space launc in 1981?

Printed Circuit Board

2009-08-28T06:29:00.001-07:00

I begin the process of making printed circuit boards (PCBs) by using a programm called Ares Lite. The file is printed as a copper mask and transferred to a presensitized sheet of copper clad. The copper clad is manufactured by a company named DALPro and they're based in St. Louis. This weekend I'll get a chance to pay them a visit and I'll post my impressions.

The product is great, I encourage everyone to try it out.

Smart Proxmity Detector

2009-08-27T12:17:00.000-07:00

I'm soldering a smart proxmity detector PCB. It uses a PICAXE-08 and will communicate with the robot it is attached to. The idea is that its PICAXE flashes two IR LEDs in sequence and looks for a sign of a reflection from the 40 kHz IR detector. The result is sent to the robot controller as a serial message. The PICAXE can operate the IR LEDs at a range of frequencies, allowing the proximity detector to estimate distances to obstacles. Since there are two IR LEDs, the proximity detector determines whether the obstacle is on the left, right, or both sides.

NearSys Ultralight flight computer

2009-08-26T09:41:00.000-07:00

I'm still plugging away at soldering the new flight computer together. It uses an I2C memory chip to store data in EEPROM. A MicroTrak 300 is the onboard transmitter. The goal is an affordable solder kit to help new groups get near spaceborne.

New Flight Computer

2009-08-25T12:54:00.003-07:00

I just received a new flight computer PCB. This one uses a PICAXE-28X and reads GPS data in background. Its built-in radio is a 144.390 MHz transmitter by Lemos. The pads for the antenna connector are good but for one. I'll drill it out for this test, but will modify it for the production boards.

New Flight

2009-08-25T12:54:00.001-07:00

Channels in Styrofoam

2009-08-24T11:46:00.001-07:00

To avoid taking up volume inside the BalloonSat airframe, I cut channels into the walls of the Styrofoam and glue my tubes and dowels. It takes a little pre-thought when designing, but the result is a BalloonSat with the maximum interior volume.

Styrofoam

2009-08-23T15:16:00.000-07:00

Lowes is selling sheets of 1/2 inch thick Styrofoam for $10. The sheets are four feet by eight feet and made from the "softer" blue Styrofoam. With 32 square feet of the stuff, you can make an entire fleet of BalloonSats.