US 12,233,542 B2
Fault detection response in a robot arm
Paul Roberts, Cambridge (GB)
Assigned to CMR Surgical Limited, Cambridge (GB)
Appl. No. 17/767,644
Filed by CMR Surgical Limited, Cambridge (GB)
PCT Filed Oct. 9, 2020, PCT No. PCT/GB2020/052528
§ 371(c)(1), (2) Date Apr. 8, 2022,
PCT Pub. No. WO2021/069925, PCT Pub. Date Apr. 15, 2021.
Claims priority of application No. 1914737 (GB), filed on Oct. 11, 2019.
Prior Publication US 2024/0100722 A1, Mar. 28, 2024
Int. Cl. B25J 19/00 (2006.01); B25J 9/16 (2006.01); B25J 18/06 (2006.01); H02P 3/02 (2006.01); H02P 3/18 (2006.01); H02P 29/024 (2016.01)
CPC B25J 19/0004 (2013.01) [B25J 9/1602 (2013.01); B25J 9/1674 (2013.01); B25J 18/06 (2013.01); H02P 3/025 (2013.01); H02P 3/18 (2013.01); H02P 29/024 (2013.01)] 19 Claims
OG exemplary drawing
 
1. 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.