Servo Testing

I managed to pull some motivation together and got some work done on the robot. I started testing a miniature H-bridge drive, but there are some problems with that. I’m not sure whether it is the breadboard or the components so I will have to look into that another time.

I started thinking about using modified servos as drive motors. This involves (in the crudest version of the mod) cutting the shaft off the feedback pot and removing the stop on the output shaft cog so it will spin through 360 degrees. Modified it fine but could not get it to spin at all. Went back a step and found that there was no serial data to the servo controller. Of course I connected ttyS1 instead of ttyS2 (man I love how much IO you can do with the gumstixs!) so after I corrected that the data began to flow. Still no servo action though.

Now I thought lets bring out the big guns. Out came the CRO and I hooked her up to the servo output on the controller to see what signal was present. More pictures after the jump.

Gumstix Range Finder Testing

Thought I better get some work happening on my robot. Shown in the picture below is the test setup for the ultrasonic range finder. It has serial and analogue outputs and can detect from about 10mm to 3m with reasonable accuracy (I think; I probably better go and find the data sheet). I decided on using the analogue output; I prefer reading an ADC than some serial data.

I wrote a small program using the i2c-io library to gain access to the robostix’s ADC lines over the i2c bus to the gumstix. It would read the ADC and print the returned value so I could verify the accuracy and the highest frequency that I could poll the ADC.

Edit: I can not spell, sorry!