Method and system for determination of at least one property of a joint

A method for determining at least one property of a joint (112, 114, 116-119, 180) of a manipulator (110), said method comprising positioning a movable part of said manipulator (110) at a clamping item (160) within a work-space of the manipulator (110) and contacting one point on the clamping item (160) with said movable part, and further comprising:

• (a) clamping (200) said joint (112, 114, 116-119, 180) such that joint motion becomes constrained;
• (b) actuating (210) said drivetrain with an actuator, while monitoring at least one quantity representing a torque of said actuator and at least one quantity representing the actuator position sensed with a motor angle sensor, such that the actuator reciprocates between a first position and a second position, and such that fully-developed drivetrain torque transmission, in opposite directions, is accomplished in both the first position and the second position, whereas the at least one monitored quantity representing the torque of said actuator and the at least one quantity representing the actuator position form hysteresis cycle data;
• (c) determining (220) at least one set of output values of said actuator based on the obtained hysteresis cycle data, said set of output values being related to at least one joint position;
• and
• (d) determining (230) the at least one property of the joint (112, 114, 116-119, 180) based on said at least one set of output values.

A system (100) for determining at least one property of a joint (112, 114, 116-119, 180) of a manipulator (110), wherein the system includes at least one actuator configured to drive said joint (112, 114, 116-119, 180) via a drivetrain, the system (100) comprising:

• a clamping device (160) configured to constrain joint motion of the joint (112, 114, 116-119, 180);
• a controller (140) configured to control motion of said joint (112, 114, 116-119, 180) and to actuate said drivetrain such that the actuator reciprocates between a first position and a second position, and such that fully-developed drivetrain torque transmission, in opposite directions, is accomplished in both the first position and the second position;
• means for monitoring at least one quantity representing a torque of said actuator and at least one quantity representing the actuator position sensed with a motor angle sensor, while actuating said drive train, wherein the at least one monitored quantity representing the torque of said actuator and the at least one quantity representing the actuator position form hysteresis cycle data;
• means for determining at least one output value of said actuator based on the obtained hysteresis cycle data, said output value corresponding to at least one joint position;
• and
• means for determining the at least one property of the joint (112, 114, 116-119, 180) based on said at least one output value.