I decided to set Clarise aside for the time being, as I was unable to solve the mystery of the twitching shoulder. I think, perhaps, some sort of worm-gear arrangement might be the ticket. I recently came into possession of a short-circuited electric mixer that has a set of gears that may be suitable. However, that’s a project for another time.
I decided to return my attention to Rover, and build a bicore head unit that would sit in the empty area just fore of the motor controller. The idea was that as the head tracked light sources, it would also turn a cam which could close switches telling the robot to turn either to the left or to the right.
So I followed the diagrams shown in Bugbots, Junkbots, and Bots On Wheels . Unfortunately, the circuit I ended up with seems not to be able to supply enough current to the motor to move much of anything. I now see that this is likely due to my using the 74HCT240 instead of the 74AC240. So I think I’ll visit my neighborhood electronics store tomorrow and see about getting the correct part.
If that doesn’t work, I found another design that looks intriguing. A diagram in that article calls to mind an exhbit that I saw ages ago at the Exploratorium. There was a large paiper-mache head with lightbulbs for eyes that somehow tracked the movement of visitors. I’ve searched their site and didn’t see any mention of it. If anyone else remembers this device and how it worked, I’d be interested to hear it.