Adaptive Robust Synchronization Control of a Dual-Linear-Motor-Driven Gantry With Rotational Dynamics and Accurate Online Parameter Estimation

For dual-linear-motor-driven (DLMD) gantry systems widely used in industrial applications, the strong mechanical coupling usually makes it difficult to achieve both good tracking and smooth operation performance simultaneously. In most of the existing control schemes, only the pure motion synchronization is considered, which may produce large internal forces leading to performance degradation and control chattering/saturation. In this paper, an accurate MIMO mathematical model of a DLMD gantry including both the traditional linear motion and the previously ignored rotational motion around the mass center is given, leading to a better understanding of the mechanical coupling and the internal forces caused by the rotational dynamics. Additionally, some physical parameters in the rotational dynamics having significant influences on the synchronization performance are discussed (e.g., the actual centroid position essentially determines the proper thrusts assigned to two parallel motors). An advanced synchronization control scheme is presented subsequently by directly considering the additive rotational dynamics and accurate parameter estimation (e.g., the actual centroid position), which not only synchronizes the motions of two parallel motors but also regulates the internal forces. The technique of integrated desired compensation direct/indirect adaptive robust control is applied to synthesize the synchronization controller for both accurate parameter estimation and a guaranteed robust performance to various uncertainties. Comparative experiments with previous control schemes show the effectiveness and better synchronization performance of the proposed method.