Bilateral Teleoperation of a Multi-Robot Formation with Time-Varying Delays using Adaptive Impedance Control

This paper proposes a decentralized adaptive impedance control approach to the bilateral control of a team of mobile robots under time-varying delays. A masterslave framework is developed and a decoupled approach is taken to ensure stability and allow for different formation controllers to be implemented. A novel decentralized method of estimating the center of formation is formulated. An adaptive impedance controller is proposed where the impedance parameters are functions of the error between the estimated center of formation and desired center of formation. In comparison to traditional tank-based passivity control for the teleoperation channels, this approach provides more accurate stiffness following and fewer open parameters that must be tuned. The purpose of the force feedback is to reflect the information of the environment to the operator to provide a transparent representation of the environment and the formation performance. This feedback encourages the operator to command the team in a motion that maintains formation and maneuvers around obstacles. Simulations and experiments with a Phantom Omni haptic device and three TurtleBot3 mobile robots are conducted to validate the proposed framework in the presence of time-varying delays.