A control system for a rod pumping unit is disclosed herein. The control system includes a memory device, a sensor, and a processor. The memory device is configured to store a velocity profile for controlling a sucker rod string of the rod pumping unit. The sensor is configured to take measurements for determining surface load of the sucker rod string. The processor is configured to gain access to the memory device and the velocity profile. The processor is further configured to determine a reference force. The processor is further configured to receive a measurement from the sensor and determine the surface load. The processor is further configured to compute a desired velocity for commanding the rod pumping unit. The desired velocity is computed based on a reference velocity from the velocity profile, the reference force, and the surface load.