ARHAB Email Traffic

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

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

(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

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

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

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

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.....