October 2012

"Doubtful" - Which is how I feel about making this thing actually balance, thus the name.

First attempt at a balancer - going with a couple downward IR sensors, gear motors, large wheels, and inverted pendulum approach. I've seen it done in a Basic Stamp so it should work in a BX24 which is what I've used most over time. I do have an Adruino board in the box but would rather stick with a language I know to get this started.

The overall concept is a locked anti-phase PWM control of geared motors using two Sharp IR sensors to read distance to ground and top vertical mounted batteries for an inverted pendulum solution.

Two 4xAAA battery packs will be mounted vertically back to back for top weight. Small home built BX24 CPU board mounted just above the PWM H-Bridge board.

This motor board is wired for locked anti-phase using an H-Bridge and a 74HC04 inverter which provides for two total pins for motor control - Left and Right. The PWM rate determines if the motor is moving forward, backward, or locked at zero. This uses more current I guess but takes away any freewheeling possibilities or motor kick in surging (hopefully at least).

Motors are some micro geared versions but they do have some gear slack which is a concern. Just a little but I'm guessing it could play havoc with keeping things balanced. Time will tell. If I find something better I'll swap them out but they are brand new "out of the bag" motors which I am not overaly happy with.

I may need to adjust the IR sensors to angle out more for better response after I get it wired up and some test code running. Hopefully not as I would like to end up with a "hood" or something that pretty much covers it all up and has some LDRs and sonar sensors in it for object avoidance.

The top button will be used to 'calibrate' or orient the code when first starting up and the on/off switch is in the middle which will switch between run and a built in charging jack like my others bots are.

I do plan on adding an output LED that ligths when the thing thinks it's balanced for debugging purposes.

I know, the long screws are UGLY - I will be replacing them with appropriate ones when I can find some that will fit right.

Overall this should be a challenge and we'll see how it goes. Long term I do not want something that just stands there balancing so getting it to move will be the next step IF if ever actually does balance.

Worst case if I can never get it to balance I'll add a tail wheel and have a tall skinny robot to run around. :-)