Robust prediction-based control for unknown time-varying delays and disturbances in spherical motion platform

Abstract

This paper presents a new prediction-based controller utilizing enhanced preview and state prediction methods to deal with unknown time-varying delays and disturbances. In practice, uncertain and variable time delays in virtual reality applications can lead to control instability and a significant reduction in the overall sense of realism. In this paper, a robust prediction-based control (RPC) is proposed for the spherical motion platform (SMP) to compensate for the effects of the time-varying delays and disturbances. The RPC comprises a preview strategy and state/disturbance prediction methods with an estimator to handle unknown time-varying delays. In addition, a newly proposed preview method improves the system's ability to follow a time-varying reference trajectory. The stability analysis for the time-delayed system incorporating the RPC is conducted using the Lyapunov-Krasovskii approach. Numerical simulations and various experiments demonstrate that the RPC effectively leads the state to converge to the desired trajectory within an error bound under various conditions of time-varying delays in the presence of disturbances, whereas the existing controllers have limitations in reducing the desired control errors. Consequently, the results validate the feasibility and effectiveness of the RPC in real-world applications, demonstrating its robustness in handling time-varying delays through practical implementation on the SMP.