This is an experiment to see what sort of robot can be made with a cheap picaxe08M. It is also the first time I've actually used my "reusable robot base" as a robot rather than a power supply / test bed. The program (see attachments) is very basic and only uses about 2/3rds of the 08M's memory so there is reasonable room for improvements.
One curious feature of this robot is that it doesn't always do what it is supposed to, sometimes it will go towards an obstacle instead of away from it as though it wants to examine the object. I haven't bothered trying to correct this apparent fault as it makes the robot appear to be curious about things.
To make the most of the picaxe08M's 5 pins I'm using the maxbotix sonars pulsewidth output since pin 3 is input only but doesn't read analog inputs.
I've been a bit slack (or is that creative) with power to the servos. I really should power them straight from the batteries with a couple of diodes in series to drop the voltage down to 6V. Instead they are running off of the 5V supply which has a 0.047F (47000uF) 5.5V super cap on it to absorb the spikes. This seems to work quit well with no servo jitter.
Click on image for a closer view.
Sunday 28th December 2008
Found the fault in my code, the turn left and turn right subroutines were turning in the opposite direction (thats what happens when you write code late at night). The new sane code (see attachments) is far more predictable but also less interesting as you can see in the second video. I've also made him backup more often to avoid getting stuck so much (as suggested by Frits).
My smallest robot is now joining the list of LMR robots to be produced by DAGU. Although he has been re-designed a bit with some new features and a new name. Mr. General (general purpose) is just that, with the breadboard allowing easy use of any microcontroller.