Elastic rotary actuator, particularly for robotic applications, and method for controlling the same

A method for controlling an elastic rotary actuator comprises an output member rotatable around an axis of rotation, an input member rotatable around said axis of rotation, elastic members interposed between the output member and the input member in such a way as to allow, due to their elastic deformation, a relative rotation between the input member and the output member around said axis of rotation, the input member being rotatable around said axis of rotation independently of the output member by way of said elastic members, and a motor assembly arranged to drive the input member to rotate around said axis of rotation, the method comprising the steps of:

• a) defining a desired value for the impedance of actuator;
• b) determining the desired angular velocity of the input member on the basis of the desired impedance value;
• c) detecting the actual angular velocity of the input member;
• and
• d) controlling the motor assembly on the basis of the error between the desired angular velocity and the detected actual angular velocity of the input member.

An elastic rotary actuator comprising:

• an output member rotatable around an axis of rotation;
• an input member rotatable around said axis of rotation;
• elastic members, each elastic member having a first end and a second end, wherein the first end is affixed to the input member and the second end is affixed to the output member, thereby allowing a rotation of the input member relative to the output member around said axis of rotation;
• a motor assembly arranged to drive the input member to rotate around said axis of rotation;
• and
• a control device arranged to control the motor assembly, said control device comprising a first sensor adapted to provide a signal indicative of the angular velocity of the input member, and an electronic control unit arranged to determine a desired angular velocity of the input member on the basis of a desired impedance value for the actuator and to control the motor assembly on the basis of the error between the desired angular velocity of the input member and the angular velocity of the input member determined from the signal provided by said first sensor.

An elastic rotary actuator comprising:

• an output member rotatable around an axis of rotation;
• an input member rotatable around said axis of rotation;
• elastic members, each elastic member having a longitudinal axis lying in a plane normal to said axis of rotation, each elastic member having a first end and a second end along said longitudinal axis, wherein the first end is affixed to the input member and the second end is affixed to the output member, thereby allowing the input member to rotate around said axis of rotation relative to a frame of reference in which the output member is immobile, wherein a rotation vector of said rotation is collinear to the axis of rotation;
• a motor assembly arranged to drive the input member to rotate around said axis of rotation;
• and
• a control device arranged to control the motor assembly, said control device comprising a first sensor adapted to provide a signal indicative of the angular velocity of the input member, and an electronic control unit arranged to determine a desired angular velocity of the input member on the basis of a desired impedance value for the actuator and to control the motor assembly on the basis of the error between the desired angular velocity of the input member and the angular velocity of the input member determined from the signal provided by said first sensor.