Prediction-Based Preview Control of Motion Platform With Time Delay

This paper presents a new control strategy for a spherical motion platform capable of three DOFs translational and three DOFs unlimited rotational motion undergoing time delay problems. The control is based on a state prediction and preview method to make a state correctly track a time-varying desired trajectory despite input time delay and disturbance. The spherical motion platform can suffer from a delay effect since it needs a wireless data link to control a cockpit sphere without any mechanical linkage. The delay decreases operation efficiency and further causes control instability. The proposed prediction-based preview control (PPC) offers that a state vector under input time delay is predicted using a disturbance predictor attenuating the disturbance effect. In addition, a predictor-based previewed reference with the state prediction is applied to the controller to achieve desired tracking control. In numerical simulations, it is shown that the proposed controller stabilizes the state to the desired trajectory under delay and disturbance, whereas most existing controllers only show delayed tracking. Finally, the proposed controller is applied to the motion platform, and the result shows excellent performance minimizing the effect of time delay and disturbance.