Experimental study on stability of a haptic system with variable time delays

Stability of force feedback haptic systems under variable time delays remains a major challenge. This paper presents a theoretical and experimental approach for studying the stability of a haptic interface in interaction with a virtual environment. A novel approach based on Lyapunov theory for assuring the stability of haptic systems under constant and variable time delays is firstly presented through conditions in terms of linear matrix inequalities (LMI). The description of a 1 DOF test bench, the experimental protocol and results are next included in order to highlight significant effects of the time delays on the stability, especially for variable time delay. The effects of backward finite difference method, first-order low-pass filter and buffer technique are also examined through an experimental stability domain.