A system for hydraulically actuating at least one degree of freedom, said system comprising: at least two actuator modules (110,0120, 130), a single prime mover for the at least two actuation modules (110,120,130), 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 (111,121,131) 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 (111,121,131) for each of said at least two actuation modules (110,120,130), 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 (110,120,130), the force or motion of the output actuator by controlling the displacement varying actuator (111,121,131). at least two actuator modules (110,0120, 130), a single prime mover for the at least two actuation modules (110,120,130), 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 (111,121,131) 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 (111,121,131) 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 (111,121,131) for each of said at least two actuation modules (110,120,130), 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 (110,120,130), the force or motion of the output actuator by controlling the displacement varying actuator (111,121,131).