Human-in-the-Loop Stability Analysis of Haptic Rendering With Time Delay - The Effect of Delayed Feedback Control in the Operator Model

Abstract

Stability analysis in haptic systems with delay most often overlooks the impact of the operator, resulting in conservative stability boundaries that limit the effectiveness of haptic feedback. To address this limitation and develop a human-centered approach to stability analysis, we investigate the impact of human feedback control on the stability of time-delayed haptic systems. Our proposed coupled model captures the interaction between the operator and the haptic system, encompassing the haptic device, virtual environment, haptic delay, arm impedance, and a controller consisting of feed-forward and feedback elements, along with a physiological delay. We present a methodology for analyzing the stability of the model, considering both time delays, where the physiological delay is constant and known. Through our analysis, we demonstrate the stability boundaries and performance achieved by various feedback control architectures and show that the coupled system can maintain stability and reasonable performance even with significant haptic delays. The findings highlight the importance of including the human operator in stability analysis, as it significantly expands the boundaries for safe haptic feedback, thereby enhancing the applicability of haptic and teleoperation systems.