A system for hydraulically actuating at least one degree of freedom, said system comprising: at least two actuator modules , a single prime mover for the at least two actuation modules , wherein the prime mover produces rotary motion and is constituted by a battery powered electric motor, and each actuation module including: an over-center variable displacement pump , said pump having: (a) a power input connection configured to power the pump from said prime mover ; and (b) a displacement varying input for varying the displacement of the pump ; and a displacement varying actuator configured to modulate the displacement varying input of the pump ; an output actuator in direct communication with the pump , said output actuator being configured to drive a corresponding degree of freedom; and a feedback measurement that represents a force or motion of the output actuator , said feedback measurement being constructed from at least one sensor ; wherein the system also comprises a controller configured to control the prime mover and the displacement varying actuator for each of said at least two actuation modules , wherein said controller further controls motion of the prime mover and uses the feedback measurement to regulate, for a respective one of said at least two actuation modules , the force or motion of the output actuator by controlling the displacement varying actuator . at least two actuator modules , a single prime mover for the at least two actuation modules , wherein the prime mover produces rotary motion and is constituted by a battery powered electric motor, and each actuation module including: an over-center variable displacement pump , said pump having: (a) a power input connection configured to power the pump from said prime mover ; and (b) a displacement varying input for varying the displacement of the pump ; and a displacement varying actuator configured to modulate the displacement varying input of the pump ; an output actuator in direct communication with the pump , said output actuator being configured to drive a corresponding degree of freedom; and a feedback measurement that represents a force or motion of the output actuator , said feedback measurement being constructed from at least one sensor ; wherein the system also comprises an over-center variable displacement pump , said pump having: (a) a power input connection configured to power the pump from said prime mover ; and (b) a displacement varying input for varying the displacement of the pump ; and (a) a power input connection configured to power the pump from said prime mover ; and (b) a displacement varying input for varying the displacement of the pump ; and a displacement varying actuator configured to modulate the displacement varying input of the pump ; an output actuator in direct communication with the pump , said output actuator being configured to drive a corresponding degree of freedom; and a feedback measurement that represents a force or motion of the output actuator , said feedback measurement being constructed from at least one sensor ; wherein the system also comprises a controller configured to control the prime mover and the displacement varying actuator for each of said at least two actuation modules , wherein said controller further controls motion of the prime mover and uses the feedback measurement to regulate, for a respective one of said at least two actuation modules , the force or motion of the output actuator by controlling the displacement varying actuator . <EOS>