工业机器人关节闭环反馈精度补偿技术

Accuracy Compensation Technology of Closed⁃Loop Feedback of Industrial Robot Joints

现有的运动学参数标定方法无法进一步提升机器人的绝对定位精度,是由于关节运动回差引起机器人定位误差具有不确定性。为此,提出了一种机器人关节闭环反馈精度补偿方法。首先,建立了综合考虑几何误差和非几何误差的切比雪夫多项式误差估计模型。然后,为了降低关节运动回差的影响,在机器人关节处安装绝对式直线光栅,将末端位置误差映射到关节转角上,得到关节转角修正量,通过关节闭环反馈控制实现机器人末端位置误差的在线修正。最后,以工业机器KUKA KR210为对象进行试验验证,试验结果表明,机器人的绝对定位误差最大值由补偿前的0.76 mm降低到0.19 mm,最大绝对定位误差降幅达到75%。该方法能够对关节运动回差进行有效地补偿,从而进一步提高机器人的绝对定位精度。

The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this problem,a closed‑loop feedback accuracy compensation method for robot joints was proposed.Firstly,a Chebyshev polynomial error estimation model was established which took geometric error and non‑geometric error into account.In addition,the absolute linear grating scale was installed at each joint of the robot and the positioning error of the robot end was mapped to the joint angle.And the joint angle corrected value was obtained.Furthermore,the closed‑loop feedback of robot joints was established to realize the online correction of the positioning error.Finally,an experiment on the KUKA KR210 industrial robot was conducted to demonstrate the effectiveness of the method.The result shows that the maximum absolute positioning error of the robot is reduced by 75%from 0.76 mm to 0.19 mm.This method can compensate the robot joint backlash effectively and further improve the absolute positioning accuracy of the robot.