Powered prosthesis with torque-sensitive actuation

A powered prosthesis device, comprising:

• an artificial joint body, pivotal about a joint axle rotatable about a joint axis;
• an input motor;
• and
• a transmission, operable to transfer force from the input motor to the artificial joint body, the transmission including:
• a crank, pivotally coupled to the artificial joint body about a crank axle rotatable about a crank axis, the input motor being rotatably coupled to the crank such that movement of the input motor causes the crank to pivot about the crank axis, the crank axis and the joint axis being laterally displaced from one another;
• a primary compression spring, rotatably coupled to the artificial joint body and rotatably coupled to the crank, the primary compression spring being continually compressed between the crank and the artificial joint body through a full range of motion of the artificial joint body;
• a secondary compression spring, carried by the artificial joint body and separably contactable by the crank;
• a ball screw spindle, rotatable by the input motor;
• a ball nut, threadably engaged with the ball screw spindle such that rotation of the ball screw spindle results in translation of the ball nut;
• and
• a connecting arm, extending between the ball nut and an input side of the crank to translate movement of the ball nut into movement of the crank;
• the input motor including a rotor, the rotor being fixed relative to the ball screw spindle such that movement of the rotor results directly in movement of the ball screw spindle;
• wherein movement of the ball screw spindle results in the crank transferring force to the artificial joint body about the crank axle and through the primary compression spring to cause the artificial joint body to pivot about the joint axis;
• a primary pre-loader threadably engageable with the primary compression spring, wherein rotating the primary pre-loader results in pre-loading the primary compression spring by compressing the primary compression spring;
• and
• a secondary pre-loader threadably engageable with the secondary compression spring, wherein rotating the secondary pre-loader results in pre-loading the secondary compression spring by compressing the secondary compression spring when in contact with the crank;
• wherein a range of motion of the artificial joint body includes:
• i) a first transmission ratio configuration in which the crank engages both the primary and secondary compression springs;
• and ii) a second transmission ratio configuration in which the crank remains engaged with the primary compression spring and is separated from contact with the secondary compression spring.