Robot and spot welding robot with learning control function

A spot welding robot comprising:

• a robot mechanism unit that comprises a control target part that is subject to position control and a sensor that is mounted on the control target part;
• a normal control unit that acquires position command data related to a target trajectory or target position of the control target part, and, according to position error data that is calculated using the position command data, operates the robot mechanism unit at a predetermined operation speed, by a task program;
• and
• a learning control unit that calculates a trajectory or position of the control target part from a detection result of the sensor, and, by learning control, calculates a learning correction amount, configured to correct a trajectory error between the trajectory and the target trajectory or a position error between the position and the target position, or reduce a vibration of the control target part that is produced when the robot mechanism unit is operated,
• wherein:
• the normal control unit corrects the position error data using the learning correction amount;
• and
• the learning control unit, in a course of calculating the learning correction amount, calculates maximum speed overrides based on maximum acceleration and maximum speed, respectively, that can be tolerated in the robot mechanism unit by operating the robot mechanism unit, and calculates a maximum operation speed that can be set in the robot mechanism unit based on the minimum value among the calculated maximum speed overrides, and calculates the learning correction amount while increasing the operation speed in one time or over a plurality of times until reaching the maximum operation speed.

A spot welding robot comprising:

• a robot mechanism unit that comprises a control target part that is subject to position control and a sensor that is mounted on the control target part;
• a normal control unit that acquires position command data related to a target trajectory or target position of the control target part, and, according to position error data that is calculated using the position command data, operates the robot mechanism unit at a predetermined operation speed, by a task program;
• and
• a learning control unit that calculates a trajectory or position of the control target part from a detection result of the sensor, and, by learning control, calculates a learning correction amount, configured to correct a trajectory error between the trajectory and the target trajectory or a position error between the position and the target position, or reduce a vibration of the control target part that is produced when the robot mechanism unit is operated,
• wherein:
• the normal control unit corrects the position error data using the learning correction amount;
• and
• the learning control unit performs a process of calculating the learning correction amount and comparing the trajectory error or the position error, or the vibration, with each threshold that is set in advance, and repeats the process, while increasing the operation speed, until the trajectory error or the position error, or the vibration, exceeds each threshold, and increases the operation speed by repeating process of increasing a predetermined amount of override, as long as the trajectory error or the position error, or the vibration, stays within each threshold in a predetermined period before the end of the operation period.