Robotic Arm Redux

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

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

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

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