Device and method for resistive torque control in a magnetorheological actuator using a recovery pulse

A prosthetic or orthotic device, comprising:

• an elongate frame configured to house electronics;
• an actuator movably coupled to the elongate frame, the actuator configured to rotate in an anterior-posterior direction about a medial-lateral axis, the actuator comprising a magnetorheological (MR) fluid and a coil operable to selectively apply a magnetic field to the MR fluid to vary its viscosity and thereby vary a torsional resistance of the actuator about the medial-lateral axis;
• and
• circuitry configured to control an amplitude and a direction of a current applied to the coil, the circuitry configured to switch a direction of current passing through the coil and to apply a reverse direction current pulse to the coil to reduce a time period over which a resistive torque of the actuator in a braking state decreases to a baseline resistance amount of the actuator in a non-braking state;
• wherein the amplitude of the reverse direction current pulse is equal to or greater than an amplitude of a step current input by the circuitry to the actuator to provide the resistive torque;
• and
• wherein one or both of an amplitude or a duration of the reverse direction current pulse is determined in part based on an approximated level of torque present in the actuator, and wherein one or both of the amplitude and the duration of the reverse direction current pulse is adjustable based on an amount of energy in the actuator required to be dissipated.