a lower limb prosthesis system and a method of controlling the prosthesis system to replace a missing lower extremity of an individual and perform a gait cycle are disclosed . the prosthesis system has a controller , one or more sensors , a prosthetic foot , and a movable ankle joint member coupled to the prosthetic foot . the movable ankle joint member comprises a hydraulic damping system that provides the ankle joint member damping resistance . the controller varies the damping resistance by providing volumetric flow control to the hydraulic damping system based on sensor data . in one embodiment , the hydraulic damping system comprises a hydraulic piston cylinder assembly , hydraulic fluid , and a valve to regulate the fluid . in one embodiment , the controller alters the damping resistance by modulating the valve to vary the hydraulic fluid flow within the hydraulic piston cylinder assembly of the movable ankle joint member based on sensor data .