Transparent Virtual Coupler Design for Networked Haptic Systems With a Mixed Virtual Wall

In this paper, a virtual coupler is designed for the Phantom Omni haptic system in the wireless networked environment with 1 degree-of-freedom interaction. The manipulator and the control computer are connected through wireless communication links over which the position of the manipulator and the torque of the motor are transmitted. The virtual environment consists of multiple materials with different stiffness and damping that is termed as the mixed virtual wall. The contact point between the avatar and the virtual wall switches among different materials, where the movement is characterized by a stochastic process. To achieve the free oscillation for the haptic device with the human operator based on the passivity theory, the stability condition is established. After transforming the transparent virtual coupler design problem into an H_∞ optimization problem for a delayed jump linear system, we propose a design scheme for the switching virtual coupler. The performance of the proposed virtual coupler is verified and tested on the Phantom Omni haptic system.