Adaptive Global Sliding Mode Contour Control of Direct Drive H-type Platform Based on Integrated Error

Aiming at the problem that synchronous error and system load change affect contour tracking accuracy when direct drive H-type platform is tracking nonlinear trajectory, a control strategy based on integrated error combining the sliding mode contour controller and the optimal position controller was proposed. The deflection angle of cross beam (X-axis) caused by the nonsynchronous of parallel axis position was defined as equivalent synchronizing error. Based on the equivalent error model, an integrated error model suitable for H-type platform contour control was built, and an adaptive global sliding mode contour controller was designed with the integrated error as the state variable, so as to eliminate the influence of synchronization error and suppress the influence of load change on contour control accuracy. The parameters of the position controller were solved by frequency domain factorization of the optimal system to improve the dynamic response performance of the single-axis servo system and reduce the position overshoot. Finally, the experimental results verify that the proposed control strategy can effectively reduce the contour error and synchronization error of direct drive H-type platform servo system, and enhance the robustness of the system. © 2020 Chin. Soc. for Elec. Eng.