Joint actuation mechanism for a prosthetic and/or orthotic device having a compliant transmission

A prosthetic knee device comprising:

• a knee-joint assembly comprising a prosthetic connector configured to connect the knee joint assembly to a user, a shaft, an inward-facing spline, and a first actuator portion;
• a harmonic transmission assembly rotatably mounted on said shaft, the harmonic drive assembly comprising:
• a second actuator portion configured to interact with the first actuator portion to provide a rotational motion;
• a wave generator rotationally fixed to said second actuator portion, the wave generator comprising a transmission portion forming a generally elliptical surface at its periphery comprising a longest axis defining two contact portions;
• and
• a flexible cup comprising a flexspline, said flexspline comprising an inner surface mounted on the elliptical surface of the wave generator at the two contact portions, and an outer spline surface configured to engage with the inward-facing spline of the knee-joint assembly at locations corresponding to the two contact portions,
• wherein rotation of the wave generator causes the flexspline to flex such that the locations of engagement between the flexspline and the inward-facing spline rotates with the wave generator, and
• wherein the inward-facing spline and the flexspline have a different number of spline teeth;
• a lever fixed to the flexible cup;
• a spring assembly rotatably mounted to the lever via a moving pivot located between the spring assembly and the flexible cup, wherein the spring assembly exhibits a non-linear stiffness behavior configured to correspond with a normal human knee joint;
• and
• a shank rotatably mounted relative to the flexible cup and separately rotatably mounted to the spring assembly, such that rotation of the shank relative to the flexible cup is resisted by the spring assembly.

A prosthetic knee device comprising:

• a prosthetic connector configured to be connected to a leg socket;
• a knee joint actuator assembly comprising an actuator housing connected to the prosthetic connector and housing an actuator comprising a motor;
• a rotatable shin structure configured to rotate about a pivot axis relative to the actuator housing, said rotation configured to be powered by the actuator to cause flexion and extension movements, wherein the actuator is mounted about the pivot axis;
• a compliant transmission assembly connected between the rotatable shin structure and the knee joint actuator assembly, said compliant transmission assembly comprising a connector mounted to a compliant member and the knee joint actuator assembly, the compliant member being also mounted to the rotatable shin structure,
• a sensor that provides for torque measurement based on deflection of the compliant member;
• and
• a controller configured to use the torque measurement to control the actuator;
• wherein during a stance phase of a gait cycle the prosthetic knee device is configured so that:
• said compliant member first absorbs energy from ground contact and deflects relative to the rotatable shin structure, and then releases energy and moves back toward an undeflected position, and
• said motor of said actuator is immobilized;
• and
• wherein during a swing phase of the gait cycle the prosthetic knee device is configured so that the controller causes the actuator to adopt a force following behavior, based on the torque measurement, in cooperation with energy released or absorbed by the compliant member.