Contour Tracking of Direct Drive H-type Platform Based on Multi-axis Global Task Coordinate Frame

Abstract

In order to solve the problem of low contour accuracy of direct drive H-type platform which consists of three permanent magnet linear synchronous motors (PMLSM) in trajectory tracking with large curvature, a contour control method is proposed to establish a rigid-flexible coupling model in multi-axis global task coordinate frame (MGTCF) combined with the sliding mode controller (SMC). Firstly, in order to clarify the rotation mode of the crossbeam and establish the complete dynamic constraint relationship between the servo axes, a three- degree-of-freedom rigid-flexible coupling dynamic model of direct drive H-type platform is built. Secondly, in order to regulate the non-orthogonality between the contouring error coordinates and the tracking path coordinates in the task coordinate frame, a multi-axis global task coordinate frame is presented. Then the sliding mode controller compensates the uncertain nonlinear disturbance effectively of the system. Finally, the simulation results show that the modeling method and contour controller advanced in this paper can fully improve the contour tracking performance of the platform.