A system and method associated with the movement of a limb. In one example, the system, such as a prosthetic or orthotic system, includes an actuator that actively controls, or adjusts, the angle between a foot unit and a lower limb member. The actuator preferably selectively locks during a desired phase in a gait cycle and minimizes friction against a rotor of the actuator. A processing module may control movement of the actuator based on data obtained from a sensor module. For instance, data may include information relating to a users gait and may be used to adjust the foot unit to substantially mimic the movement of a natural ankle. The system may accommodate level ground walking, traveling up/down stairs or sloped surfaces, and various other user movements. In addition, the processing module may receive user input, such as a heel height, or display output signals through an external interface.
