Stable interaction with an n-DOF virtual object using a modified passivity based control architecture

In Networked haptic virtual environments, users can haptically interact with a shared virtual world from numerous workstations over an Ethernet local area network (LAN). Such networks suffer from the communication channels´ difficulties such as delay, jitter and pocket loss. Such hindrances lead the closed-loop system to undesirable oscillations/instability. In this paper, by a utilized Passive Set-Position Modulation (PSPM) algorithm, passivity is enforced to a networked haptic virtual environment, involving a node-based n-DOF virtual object. In order to implement numerically, a novel approach is developed to transform the resulting optimization problem to a semidefinite optimization problem. The new method eliminates boundedness on interaction´s stiffness and provides rendering interaction with either a rigid or deformable virtual object through dedicated networks or over the internet. The new modified PSPM framework was validated through some simulations.