Contouring compensation control based on high accuracy contour error estimation for multi-axis motion systems

Multi-axis motion systems have been widely applied in industrial fields, and the contour error is an important indicator to measure the quality of the products. Contour error is defined as the orthogonal deviation of actual position from the desired tool path, and contouring control is a very useful method to reduce or eliminate it. In this study, by finding the reference point nearest to the current actual position, and then projecting the actual position onto the osculating plane at this reference point, a high-accuracy contour error estimation method is proposed. When the estimated contour error cannot be described as an analytic expression of tracking errors, the cross-coupling control (CCC) is not applicable. And, task coordinate frame approach (TCFA) has a relatively complex computation. In order to overcome these shortcomings, by compensating the axis component of contour error into each loop of the servo motor simultaneously, a simple and effective contouring compensation control method is proposed. Experiments are carried out on a real-time in-house-developed multi-axis motion system. The results show that the contour error estimated by using the proposed method is close to the true one, and the proposed contouring control method can achieve the proportional reduction of the contour error effectively.