GBOT90 Balancing Bot Demo with PID

[liam.zbasic]

A previous post on the subject of GBOT with PID control was intended to make and learn the hardware and software aspects of ZX-40A microcontrollers with control systems. I used that experience to extend the GBOT into a 5 foot balancing robot. I added an aluminum frame, disabled the forward looking IR range sensors and added a new GP2D120 IR sensor for pitch control. The result is the GBOT90 shown in the link below.

Noise and resolution was an issue but manageable. The Vref was set to 3.0V to improve resolution. No gyros and no acceleromenters were used, just a single GP2D120 IR range sensor for pitch rate & angle measurements. I used the same PID control system from the GBOT but updated the gains. Proportional and integral gains were much higher. Integral gain was highest.

The Tamiya motors are controlled with PWM modulation sent to the Pololu VNH2SP30 motor driver. At low duty cycles, the motors are not synchronized. Is this expected?

http://www.youtube.com/watch?v=bxx14Xe2iNg