Artificial human limbs and joints employing actuators, springs, and variable-damper elements
Biomimetic Hybrid Actuators employed in biologically-inspired musculoskeletal architectures employ an electric motor for supplying positive energy to and storing negative energy from an artificial joint or limb, as well as elastic elements such as springs, and controllable variable damper components, for passively storing and releasing energy and providing adaptive stiffness to accommodate level ground walking as well as movement on stairs and surfaces having different slopes.
1. A prosthetic, orthotic or exoskeletal device comprising:
a mechanical ankle joint;
a motor adapted to impart a torque on the ankle joint; and
a spring arranged in parallel with the motor;
wherein the spring only engages when the ankle joint rotates past a predetermined position, wherein the predetermined position is an ankle angle of 90° or less, within the range of angles of the ankle joint where the ankle is in a position of dorsiflexion, and wherein energy stored in the spring during dorsiflexion is released to cause the ankle joint to rotate and propel powered plantarflexion.
2. The device of claim 1 , wherein the spring is adapted, when engaged, to lower a peak motor torque requirement for biologically realistic dynamic behavior.
3. The device of claim 1 , wherein the motor and spring are configured to provide biologically realistic dynamic behavior.
4. The device of claim 1 further comprising at least one elastic element in series with the motor.
5. The device of claim 4 , wherein at least one of the spring and the elastic element is adapted to store energy in one phase of the gait cycle and to release energy in a subsequent phase of the gait cycle.
6. The device of claim 1 further comprising a transmission operatively connected to an output of the motor.
7. The device of claim 1 further comprising a motor parallel damper.
8. The device of claim 7 , wherein the motor parallel damper is adapted to be locked at certain times.
9. The device of claim 7 , wherein the motor parallel damper is selected from the group consisting of a rotary magnetorheological (MR) variable damper and a rotary hysteresis variable damper.