Novel kinematic model of a SCARA-type robot with bi-directional angular positioning deviation of rotary axes
Novel kinematic model of a SCARA-type robot with bi-directional angular positioning deviation of rotary axes
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DOI：
10.1007/s00170-022-08943-5
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Nan Zhao;S. Ibaraki
中科院分区：
文献类型：
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作者：
Nan Zhao;S. Ibaraki
本文提出了一种运动学模型及其标定方案，以进一步提高工业机器人在整个工作空间内的绝对定位精度。为了证明所提出的模型及其在简化运动学方面的有效性，本文仅针对 SCARA（选择性顺应装配机器人手臂）型机器人。所提出的模型不仅包括连杆长度误差和旋转轴角度偏移（广泛称为 Denavit-Hartenberg (D-H) 参数），还包括每个旋转轴的角度定位偏差的“误差图”（建模为命令角位置的函数）和旋转方向，以模拟间隙的影响。通过激光跟踪仪测量机器人末端执行器的位置，并在规定的角度位置对每个旋转轴进行索引，来识别每个旋转轴的角度定位偏差。为了验证识别模型的有效性，对基于该模型的补偿效果进行了实验研究。通过补偿，机器人的平均绝对位置误差降低了33%，达到0.034mm。此外，本文通过实验证明所提出的模型可以扩展到径向误差运动、轴间串扰以及具有轴平均线方向误差的三维定位。
This paper proposed a kinematic model and its calibration scheme to further improve an industrial robots absolute positioning accuracy over the entire workspace. To demonstrate the proposed model and its effectiveness in simplified kinematics, this paper only targets a SCARA (Selective Compliance Assembly Robot Arm)-type robot. The proposed model includes not only link length errors and rotary axis angular offsets, widely known as the Denavit-Hartenberg (D-H) parameters, but also the “error map” of the angular positioning deviation of each rotary axis, modelled as a function of command angular position, and the rotation direction to model the influence of backlash. The angular positioning deviation of each rotary axis is identified by measuring the robots end-effector position by a laser tracker with indexing each rotary axis at prescribed angular positions. To verify the validity of the identified model, the effectiveness of the compensation based on it is experimentally investigated. By the compensation, the robot’s average absolute position error was reduced by 33% to 0.034mm. Furthermore, this paper experimentally demonstrates that the proposed model can be extended to the radial error motion, axis-to-axis cross talk, and the three-dimensional positioning with orientation errors of axis average lines.