Fast and Accurate Motion Tracking of a Linear Motor System Under Kinematic and Dynamic Constraints: An Integrated Planning and Control Approach

Achieving a fast transient response and high steady-state tracking accuracy simultaneously has been a challenging issue for the linear motor system in the presence of kinematic and dynamic constraints, various parametric uncertainties, and uncertain nonlinearities. To this end, a two-loop control structure is developed to maximize the converging speed of the transient response and achieve high steady-state accuracy. Specifically, in the outer loop, an online trajectory replanning algorithm is devised to force the replanned trajectory to merge into the desired trajectory in minimum time under the system's kinematic and dynamic constraints. In the inner loop, an adaptive robust controller is synthesized to handle the parametric uncertainties and uncertain nonlinearities effectively so that high steady-state tracking accuracy is guaranteed. Particularly, the interaction between the two loops is intuitive since a feedforward term is optimized in the outer loop and then fed into the inner loop to make the model compensation. Comparative experiments are carried out on a linear-motor-driven system. Experimental results confirm that the proposed control structure can achieve a minimum-time transient response without violating the kinematic and dynamic constraints and also guarantee the excellent steady-state tracking accuracy.