Stable haptic interaction with virtual environments

Abstract

A haptic interface is a kinesthetic link between a human operator and a virtual environment. This paper addresses fundamental stability and performance issues associated with haptic interaction. It generalizes and extends the concept of a virtual coupling network, an artificial link between the haptic display and a virtual world, to include both the impedance and admittance models of haptic interaction. A benchmark example exposes an important duality between these two cases. Linear circuit theory is used to develop necessary and sufficient conditions for the stability of a haptic simulation, assuming the human operator and virtual environment are passive. These equations lead to an explicit design procedure for virtual coupling networks which give maximum performance while guaranteeing stability. By decoupling the haptic display control problem from the design of virtual environments, the use of a virtual coupling network frees the developer of haptic-enabled virtual reality models from issues of mechanical stability.

Remote control of an assistive robot using force feedback

“…The controller can be applied to constant or time-varying delays without any adaptation. In Figure 3.4, M(s) is the haptic device transfer function, C(s) is the local controller (virtual coupling, [16]),  i are respectively upstream and downstream time delays (taken constant on the figure) and E(s) represent the robot and its environment. F e is the slave environment computed force; F h is the operator-applied force on the device.…”

Force feedback stabilization for remote control of an assistive mobile robot

“…where M (s) is the haptic device transfer function, C(s) is local controller (virtual coupling, [12]), τ i are respectively upwards and downwards time delays (constant on the figure) and E(s) represent the robot and its environment. F e is the slave environment computed force, F h is the operator applied force on the device.…”

Stable and high performance teleoperation with time domain passivity control: reference energy following scheme

“…We assumed that there is no change in force and velocity during one sample time. Thus, we can easily "instrument" one or more blocks in the system with the following "Passivity Observer," (PO) for a one-port network to check the passivity (1).…”