Control device for compensation of elastic deformation of articulated robot

Abstract

This control device (10) for compensating for the elastic deformation of an articulated robot is configured from a joint angle command value calculation unit (100), an axial force torque calculation unit (200), a first dynamic characteristic computing unit (300), a feedback control unit (500), and a motor angle command value calculation unit (600). The first dynamic characteristic computing unit (300) is configured from an interpolation unit configured from an N-ary curve interpolation, and a filter unit configured from an M-ary filter, with N+M being at least 4.

Description

technical field [0001] The present invention relates to the control of multi-joint robots. Background technique [0002] When arc welding is used to weld a plurality of base metals, weaving welding is used in which welding is performed by performing a sinusoidal oscillating motion in the left and right directions of the welding line while advancing the welding electrode in the welding direction. Conventionally, this weaving welding has been performed by swinging the welding torch itself from side to side, or by tilting the welding torch itself to the left and right. When an articulated robot is used to perform such weaving welding, high trajectory accuracy is required. [0003] Such an articulated robot performs servo control in units of axes. However, since the natural frequency of vibration is low, from the viewpoint of vibration suppression, speed feedforward is hardly used. Compared with the target value, the phase lag of the actual feedback value is relatively large, ...

AI Technical Summary

Problems solved by technology

[0015] (1) In the state where the natural vibration of the robot is low, since the elastic deformation compensation and axial force torque compensation cannot effectively function, the influence of elastic deformation cannot be compensated, resulting in poor accuracy

[0016] (2) In the state where there is a phase lag of the servo control part, since the elastic deformation compensation control cannot be effectively functioned, the influence of the elastic deformation cannot be compensated, resulting in poor accuracy

[0017] (3) Since the servo control characteristics are different for each axis, there is a difference in the response of each axis, resulting in deterioration of trajectory accuracy

[0018] (4) When the calculation cycle of the command value lags behind the calculation cycle in the servo control section, the phase difference causes deterioration of trajectory accuracy

However, due to changes in servo characteristics due to elastic deformation caused by the reducer and differences in characteristics for each axis, it is very difficult to make the phase / gain characteristics consistent in high-frequency oscillating operations

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