Dynamical Model Based Contouring Error Position-Loop Feedforward Control for Multiaxis Motion Systems

Contouring motion control plays an important role in modern precision multiaxis motion systems. In order to enhance the coordination between each axis and promote contouring performance, many research works have been conducted that mainly focus on contouring error online estimation and control. Essentially, most of existing control strategies based on emerged contouring error belong to feedback control, which cannot achieve perfect performance due to inevitable delay or lag. To fundamentally tackle the above problem, a novel position-loop feedforward contouring control method is proposed in this paper. Specifically, according to the linear model of each axis and the kinematics characteristics of reference contour, a dynamical model of contouring error in multiaxis systems is firstly developed, which can explain the essential causes of contouring error quantificationally. Then, based on the proposed contouring error model, a position loop feedforward control strategy can be designed for contouring following tasks. The effectiveness of the proposed method is tested on a three-axis computerized numerical control systems. Various experimental results consistently demonstrate that the contouring error model can accurately predict actual contouring error to some degree. Compared with the conventionalmodel- based feedforward approach, the proposed strategy can not only point out the essential causes of contouring error directly, but also achieve better contouring performance.