US 12,214,498 B2
Robot joint torque control system and load compensation method therefor
Zhangguo Yu, Beijing (CN); Qiang Huang, Beijing (CN); Yaliang Liu, Beijing (CN); Yuyu Zuo, Beijing (CN); Xuechao Chen, Beijing (CN); Gao Huang, Beijing (CN); and Han Yu, Beijing (CN)
Assigned to BEIJING INSTITUTE OF TECHNOLOGY, Beijing (CN)
Appl. No. 17/908,238
Filed by Beijing Institute of Technology, Beijing (CN)
PCT Filed May 9, 2020, PCT No. PCT/CN2020/089342
§ 371(c)(1), (2) Date Aug. 31, 2022,
PCT Pub. No. WO2021/184517, PCT Pub. Date Sep. 23, 2021.
Claims priority of application No. 202010186117.9 (CN), filed on Mar. 17, 2020.
Prior Publication US 2023/0158669 A1, May 25, 2023
Int. Cl. B25J 9/00 (2006.01); B25J 9/16 (2006.01); B25J 13/08 (2006.01); G05B 19/4155 (2006.01)
CPC B25J 9/1633 (2013.01) [B25J 13/085 (2013.01); G05B 19/4155 (2013.01); G05B 2219/39188 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A load compensation method for a robot joint torque control system, comprising accumulating a current if whose joint-end velocity is compensated for by a load compensation controller and an original current loop input instruction ir, and then using the accumulated current as a current loop input instruction of a joint torque control system to compensate for an influence of load parameters on an output torque of the joint torque control system;
wherein an output voltage Uc of a servo motor of the joint torque control system is:
Uc=Ka(ir−KIia)
where Ka is a current loop control parameter, ir is a current loop input instruction, KI is a circuit loop feedback coefficient of the servo motor, and ia is the actual accumulated current value; the current loop input instruction ir is obtained by multiplying a joint torque error ET and a PD controller parameter KPD, and the joint torque error ET is obtained by subtracting a given torque Tr of the joint and an actual torque Tp of the joint end;
wherein voltage balance equation of the servo motor is:

OG Complex Work Unit Math
where E is a counter electromotive force of the servo motor, and

OG Complex Work Unit Math
 is a reduction ratio of the gear reducer, Kv is a velocity feedback coefficient of the servo motor, θ is an actual position of the joint end,

OG Complex Work Unit Math
 is an actual velocity of the joint end, L is an inductance of the servo motor, and R is a resistance of the servo motor;
wherein the load compensation controller is

OG Complex Work Unit Math
 wherein n is a reduction ratio of a gear reducer, Kv is a velocity feedback coefficient of a servo motor, and Ka is a current loop control parameter;
an open-loop transfer function of the joint torque control system is:

OG Complex Work Unit Math
wherein a corner frequency of an inertial element:

OG Complex Work Unit Math
 an open-loop gain

OG Complex Work Unit Math
 KPD is a PD controller parameter, Kt is a torque coefficient of the servo motor, L is an inductance of the servo motor, and R is a resistance of the servo motor.