In one embodiment, a robotic manipulator arm includes a robotic joint, a rotational position sensor, and a control system. The rotational position sensor is coupled to the main housing of the robotic joint. The control system is connected to the rotational position sensor. During normal rotational motion toward a commanded motor position of joint output, the control system determines that normal joint un-slipped motion is occurring with respect to the joint output in response to the motor input commands. Responsive to joint slip during commanded motor motion, the control system compares position data from the rotational position sensor to commanded motor position to generate an error value and, based on the error value, compensates for the joint slip.