Finite-time Controller Design for Permanent Magnet Linear Motor System with Output Tracking Error Constraint

This paper considers the finite-time motion control problem of permanent-magnet linear motor (PMLM) system with output tracking error constraint. Firstly, by choosing position error as sliding mode variable, a second-order of position dynamic error system is derived for PMLM system. Then, an finite-time disturbance observer is designed to estimate the lumped disturbance (include friction force and ripple force). Then, a constrained second-order sliding mode tracking controller is constructed by using the adding power integrator method and the estimation of the lumped disturbance. It is proved that the proposed constrained second-order sliding mode tracking controller can steer the error between the current position of PMLM and desired position to zero in finite time without violating the output tracking error constraint. Finally, simulation results demonstrate the effectiveness of the proposed control strategy.