Let's Make Robots!

New line sensor

I had some problems with the 36 KHz detector when trying to read it from the picaxe, so I have switched to using 4 infrared photodiodes in a feedback setup with two LM358 dual opamp packages as shown in the following image (for one photodiode only):

linedetector.jpg

This gives an analog reading and I will use this for linear interpolation between the sensors to determine where the line is relative to the robot center.

Simple test with PICAXE and a monster truck

Just tried out controlling my radio controlled monster truck with the picaxe. It's a simple test run of forward, turn left then right and then stop. I put the car in a spot that almost made it reach the bathroom :-). Notice how the breadboard almost flies off when the car turns... a really solid construction! :-)

bonzer_monster.jpg

I'm looking forward to making something useful out of this car... it can go pretty fast!

Dang! I can't seem to embed video in a blog post???

36 KHz modulated infrared light detector

I have started working on a new robot that is mainly based on LEGO MINDSTORMS NXT. This robot is aimed at participating in DTU robocup 2008 but time will tell if it will be finished in time. Anyway in robocup the robot must at least be good at following a black line and preferably it should be able to accomplish other of the tasks at hand as well, and this is just not feasible using the standard LEGO sensors and the very limited number of these it can use at one time.

Oh no the horror!

After testing the motor driver and writing some code to control the robot based on line sensor input, I tried it out... Nothing seemed to happen so I double-checked the PICAXE 40X1 schematics with my robot's wiring and I have completely forgotten, that the two L293 pins for enabling motors should be wired to PWM outputs (Noooooo!). I guess I'll have to get my soldering iron heated and perform surgery on poor Pete. I was so happy that all the hardware I had wired just worked the first time... and the I go and do something like this *sigh*.

Motor driver tested

Today I tested that the motor driver circuit of PICAXE Pete does in fact work. I'm now in the process of writing some code for line following using my standard technique: find out where the line is by taking the mean value of a histogram of the sensor values and using this to calculate a regulation term for each of the two motors.