Research on Contour Error Compensation Method with Matched Servo Dynamic Characteristics

doi:10.3901/JME.2017.01.150

Abstract

Abstract: In multi-axis CNC machining, the final machining precision of the parts is determined directly by the contour error. Cross-coupling controller and task coordinate frame approach can improve the contour accuracy by estimating the contour error and designing the contouring controller. There exist some problems such as the poor contour error estimation accuracy in the large curvature position and contour control gain setting depending on engineering experience with the two methods. To solve this issue, proceeding from the dynamic characteristics matching of the servo axes, a contour error compensation method based on the precise calculation of the contour error is proposed. According to the definition of the foot point, the contour error is calculated quickly and accurately using the analytical method. Then, the contour error component is compensated to every servo axis’s speed loop and torque loop to improve the matching degree of the dynamic characteristics. Finally, the experiments are conducted using the two-dimensional and three-dimensional NURBS curves. The experiment results show that the contour error can be estimated exactly by the proposed contour error calculation method. The proposed contour error compensation method does not need to establish the relationship between the contour error and the tracking errors, and reduce the contour error quantitatively and significantly by adjusting the controller gains.

Key words: compensation, contour error, contouring control, dynamic characteristics matching

LI Xiangfei, ZHAO Huan, ZHAO Xin, DING Han. Research on Contour Error Compensation Method with Matched Servo Dynamic Characteristics[J]. Journal of Mechanical Engineering, 2017, 53(1): 150-156.

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