Complex sentence: Further refinements like PID control would help compensate for additional variables like hills, where the amount of power needed for a given speed change would vary, which would be accounted for by the integral function of the PID control.
Split into simpler sentences: Further refinements like PID control would help compensate for additional variables like hills, where the amount of power needed for a given speed change would vary. This would be accounted for by the integral function of the PID control.