Actuator assembly for prosthetic or orthotic joint

A prosthetic ankle for attaching to a limb, comprising:

• a prosthetic lower limb member;
• a prosthetic foot movably coupled to the prosthetic lower limb member;
• an actuator comprising:
• a motor,
• a first threaded member that extends along a longitudinal axis of the actuator and connects to the prosthetic lower limb member, the first threaded member having a first threaded portion and configured to move along the longitudinal axis relative to the motor, and
• a second threaded member that extends along the longitudinal axis of the actuator and connects to the prosthetic foot, the second threaded member having a second threaded portion and configured to move along the longitudinal axis relative to the motor, the first and second threaded members extending from opposite sides of the motor and configured to move relative to each other,
• wherein the motor is disposed circumferentially about at least a portion of the first and second threaded members, the motor configured to axially displace outer ends of one or both of the first and second threaded members to adjust an angle between the prosthetic lower limb member and the prosthetic foot, and wherein a pitch of threads of one or both of the first and second threaded members generates a locking force when an axial load is applied to at least one of the first and second threaded members to lock the angle between the prosthetic lower limb member and the prosthetic foot.