A Practical Contouring Control Strategy Based on Accelerated Iterative Contouring Error Estimation

Aiming at the problem of improving the contouring control performance of the multi-axis system when performing periodic extreme contouring machining tasks such as high-speed and large-curvature contour, this paper proposes a contouring control strategy based on accelerated Newton iterative contouring error estimation algorithm (AccNewton-ILC-NTSMC). Firstly, a non-singular terminal sliding mode controller (NTSMC) is designed as a single-axis feedback controller to reduce the contouring error as much as possible. Then, an accelerated Newton iterative (AccNewton) algorithm with fourth-order convergence rate is designed to estimate the contouring error of the multi-axis system, and its convergence is proved theoretically, which is faster than the general iterative search method. Finally, an iterative learning controller (ILC) based on the estimated contouring error is designed as a contouring controller to achieve high-precision contouring control, and its stability is proved theoretically, which is more easier to implement than the conventional contouring control strategy. In this paper, comparative experiments are designed and carried out on a dual-axis linear motor platform to verify the proposed contouring control strategy. The experimental results illustrate that the proposed contouring strategy greatly improves the performance of contouring control compared with traditional strategy, especially when performing extreme machining curves. Moreover, the proposed AccNewton algorithm is faster, which makes the Accnewton-ILC-NTSMC strategy more suitable for multi-axis systems with high control frequency.