Multirate-Output-Estimator-Based Control for Virtual Environment with Computational Time Delay

This paper presents multirate-output-estimator-based control for haptic systems, which enhances stability of the haptic system, and increases the fidelity of the simulation by alleviating the negative effects of the computational time delay. The developed controller has a MIMO (multi-input-multi-output) output estimator with multirate sampling, and a passive output limiter. The MIMO output estimation employs a least-squares algorithm and an output error model. The output force is predicted one-step-ahead to compensate the computational time delay. The predicted force traces the actual output computed from the physics-based model. A passive output limiter controls the maximum permissible force to guarantee passivity of the haptic system at each sampling period. Efficacy of the proposed control method is demonstrated through experiments with a linear tensor-mass model with computational time delay