Robust adaptive control of a three-axis motion Simulator with state observers

The development of a nonlinear robust adaptive tracking control system for a three-axis motion simulator is presented in this paper. The motion simulator is used to test and calibrate certain spacecraft instruments within a hardware-in-the-loop environment. Permanent magnet synchronous motor (PMSM) drives are used as simulator actuators. The control system is developed based on Lyapunov stability theory for which only rotor position and stator current signals are required. By using mechanical and electrical state observers, the measurement of acceleration and load torque which is usually required when motor dynamics are considered, is avoided. The control system can be made adaptable to constant unknown motor parameters and load inertia and robust to unknown but bounded fast varying disturbances. Simulation and experimental results are presented to verify the stability and efficacy of the proposed control system.