The hardware for "Phase 0" (the preliminary test bed) of the MR01 Mars Rover is now mostly finished, and this is a first closed-loop control demo of the robot.
"Closed loop" means that each of the wheels has a Hall Effect quadrature encoder measuring its rotation, in this case 2774 ticks per rotation. This is used with a PID controller to support wheel odometry, very accurately measuring how far the wheel has traveled.
In this demo, the motor controllers (written in Python) also support both Slew and Jerk control, so there's a sense of momentum to its movement. This reduces stress on the motors' gearboxes as well as making the robot's movement smoother. The control knob on the side of the robot has zero at center-top, where rotating counter-clockwise injects a reverse velocity into its current velocity target; clockwise a forward velocity. Coupling closed-loop control with 52rpm motors means the robot can move very slowly, but still at full power (i.e., each motor will move at that rate regardless of going steeply uphill or downhill, or encountering an obstacle).
The next demo will begin to work with the steering servos on each wheel.