Reducing Kinematic Error
AssigneeABB Schweiz AG
InventorsArne Wahrburg, Richard Roberts, Stig Moberg, Nima Enayati
Life of this patent
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Abstract
A method includes determining a movement of a robot arm in which a joint while being rotated from a start angle to an end angle, is subject to a constant gravity-induced torque; controlling execution of the movement, and, in the movement, controlling the joint to rotate from the start angle to the end angle at a constant speed; detecting speed fluctuations of the joint while it is being rotated from the start angle to the end angle; and estimating the kinematic error based on the speed fluctuations.
Claims12
A method for assessing kinematic error in a joint that rotatably connects a proximal portion and a distal portion of a robot arm, the joint having associated with it a motor mounted in one of the portions and coupled to the other one of the portions for driving rotation of the joint by a transmission gear having a reduction ratio, and a sensor for measuring the rotation of the joint, the method comprising:
- a) determining a movement of the robot arm in which the joint, while being rotated from a start angle to an end angle, is subject to a constant gravity-induced torque;
- b) controlling execution of the movement and controlling the joint to rotate from the start angle to the end angle at a constant speed;
- c) detecting speed fluctuations of the joint while it is being rotated from the start angle to the end angle;
- and
- d) estimating the kinematic error based on the speed fluctuations.
A robotic system, comprising:
- a robot arm having a proximal portion, a distal portion, a joint connecting said proximal and distal portions, a motor mounted in one of the portions, a transmission gear connecting the motor to the other one of the portions for driving a rotation of the joint;
- a controller for controlling the robot arm to carry out a pre-determined movement, wherein the controller is adapted to carry out at least:
- controlling execution of the movement and controlling the joint to rotate from the start angle to the end angle at a constant speed;
- and
- detecting speed fluctuations of the joint while it is being rotated from the start angle to the end angle.
Dependencies are inferred from the claim text.