Motor control system, control method for motor control system, and robot system

A control method for a motor control system that controls a motor by controlling a current supplied to the motor based on a position command input from a host device and controls an operation of a speed reducer including an input shaft connected to an output shaft of the motor and an output shaft connected to a load, the motor control system comprising:

• a detection unit that detects an event for detecting a rotation speed of the output shaft of the motor;
• a speed deviation generation unit that generates a speed command based on the position command and calculates a speed deviation which is a deviation between the speed command and the rotation speed of the output shaft of the motor detected based on the event detected by the detection unit;
• an angular transmission error compensation unit that estimates an angular transmission error between a rotation angle of the output shaft of the motor and a rotation angle of the output shaft of the speed reducer, and corrects the speed command, the speed deviation, or the rotation speed of the output shaft of the motor detected based on the event detected by the detection unit, based on the estimated angular transmission error;
• a current command generation unit that generates a current command based on the speed deviation;
• and
• a current control unit that controls a current supplied to the motor based on the current command.

A robot system comprising:

• a robot arm;
• a motor which is a drive source of a joint of the robot arm;
• a speed reducer including an input shaft connected to an output shaft of the motor and an output shaft connected to the joint of the robot arm;
• a command unit that generates a position command;
• and
• a motor control system that controls an operation of the motor by controlling a current supplied to the motor based on the position command generated by the command unit,
• wherein the motor control system includes:
• a detection unit that detects an event for detecting a rotation speed of the output shaft of the motor;
• a speed deviation generation unit that generates a speed command based on the position command and calculates a speed deviation which is a deviation between the speed command and the rotation speed of the output shaft of the motor detected based on the event detected by the detection unit;
• an angular transmission error compensation unit that estimates an angular transmission error between a rotation angle of the output shaft of the motor and a rotation angle of the output shaft of the speed reducer, and corrects the speed command, the speed deviation, or the rotation speed of the output shaft of the motor detected based on the event detected by the detection unit, based on the estimated angular transmission error;
• a current command generation unit that generates a current command based on the speed deviation;
• and
• a current control unit that controls a current supplied to the motor based on the current command.