Stable multi-user interaction with cooperative haptic virtual environments by a modification of passive set-position modulation

This study is concerned with interaction in multi-user/cooperative haptic virtual environments. In such systems, users can haptically interact with a shared virtual world from numerous workstations over an Ethernet local area network. Characteristics of communication channels, such as delay, jitter and packet loss, can potentially investigate undesirable oscillations/instability. Passivity as a benchmark for stability, specifically in the stability analysis of coupled systems like teleoperations or haptics, has the disadvantage of being overconservative. Hence, it compromises fidelity of interaction. Passive set-position modulation (PSPM), which was first used to impose teleoperation closed-loop passivity is utilised in this study for a networked virtual haptic environment. Enforcing the closed-loop passivity of multi-user haptic interaction, this approach allows virtually all ranges of stiffness to be rendered by numerous users no matter what the network circumstances are. The new modified PSPM framework was validated through some simulations and experiments.