The invention is directed to controlling a hydraulic actuation system having at least one degree of freedom, a prime mover, at least one actuation module and a controller, with each actuation module including: an over-center variable displacement pump having a power input connection configured to power the pump from the prime mover and a displacement varying input for varying the displacement of the pump； a displacement varying actuator configured to modulate the displacement varying input of the pump； an output actuator in direct communication with the pump, the output actuator configured to drive a corresponding degree of freedom； and at least one sensor establishing a feedback measurement that represents a force or motion of the output actuator. Based on a value of each feedback measurement, the force or motion of the output actuator is regulated by controlling the prime mover and the displacement actuator for the output actuator.
