Making a quarature encoder
December 3, 2008
This is a photo of the encoder disk that I'm working on for the Hitari Tumbler robot chassis modification.
The gear wheel is driven, in the car/robot chassis, directly from an 8-tooth pinion on the motor shaft. It then transmits the drive to the front and rear wheels on one side of the chassis.I want to accurately measure the speed of this gear wheel, so that I can write a PID speed control program for the motor(s). Then, I'll have accurate odometry (distance measuring) as well as a kind of "cruise control" for the whole robot. I'll fit two IR LED/photodiode sensors in the holes in the white plastic panel, at 90 degrees to each other, relative to the gear axle. Then, using an encoder disk with an odd number of spokes, I should get quadrature signals (90 degrees out of phase). This mock-up will let me test sensor alignment and circuitry before drilling holes in the real chassis!