So I currently have a happy little robot, if you can call 180+lbs little, scooting around. 4 wheel 24V tank style controls. I have a R3 Mega runnning the show, and some VEX883 speed controllers on the motors. They are called speed controllers, but they are, afaik, just PWM sources that limit the voltage to the wheels, thereby limiting power output. I want to implement some rudimentary speed controll by looking at the back EMF of each motor, so I can tell if one is slipping so I can limit it to not throw dirt everywhere, and send a little extra juice to the wheel right behind or infront of it to keep things rolling.
My initial plan was to use the optical encoders I have in a box somewhere, but I don't really think I need that percision or complication any more. I am thinking a voltage divider to keep things in range and look at the back EMF of each motor to see who is up to what.
first question, how do i protect the Mega from pulses and other bad things? a clamping zener? does it need to be more robust? because of the drive type, do I need to filter it in some way? permanant magnet DC motors. and of course they reverse, so that must complicate things of course.
also, if you were to ballpark guess, how much resolution of wheel speed do you think I can realisticly expect? I doubt I can get real world position feedback with this system, but can I tell the difference between inside and outside wheels in a turn?
thanks guys, I know this has all been done before, but I am still looking for a good example of it, circuit design aint my strong point.