Fault detection response in a robot arm
AssigneeCmr Surgical Limited
InventorPaul Roberts
Life of this patent
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Abstract
A robot arm comprising: a first link connected to a second link by a joint, the joint permitting the second link to move relative to the first link; a motor for driving the joint; and a controller for controlling the motor. The controller is configured to electrically brake the motor in response to detection of a fault in the robot arm by applying a braking current to the motor so as to maintain the position of the joint against gravity. The controller only performs this electrical braking if the joint is in a configuration in which the robot arm will droop under gravity if the joint is not actively driven.
Claims19
A robot arm comprising:
- a first link connected to a second link by a joint, the joint permitting the second link to move relative to the first link;
- a motor configured to drive the joint, wherein the motor is a multiple-phase motor including, for each phase of the multiple phase motor:
- a motor winding;
- a motor drive circuit configured to apply drive signals to the motor winding;
- and
- a load switch configured to connect a power supply to the motor drive circuit;
- and
- a controller configured to control the motor, the controller configured to, only if the joint is in a configuration in which the robot arm will droop under gravity if the joint is not actively driven, electrically brake the motor in response to detection of a fault in the robot arm by applying a braking current to the motor so as to maintain the position of the joint against gravity.
Dependencies are inferred from the claim text.