Bilateral Teleoperation of Multiple Cooperative Robots over Delayed Communication Networks: Theory

We propose a control framework for the bilateral teleoperation between a single master robot and multiple cooperative slave robots with communication-delay in the master-slave communication channel. Using passive decomposition, we first decompose the dynamics of multiple slaves into two decoupled systems while preserving energetic passivity: the shape system describing cooperative grasping aspect, and the locked system representing overall behavior of the multiple slaves. Then, by locally controlling the decoupled shape system with the cancellation of disturbances on it, secure and tight (and possibly fixtureless) cooperative grasping can be achieved regardless of the communication-delay and human command. We also construct a bilateral teleoperation loop between the master and the locked system s.t., by operating the master, a human operator can control the overall behavior of the multiple slaves and the grasped object while perceiving environmental forces acting on them. Scattering-based communication is used to passify the master-slave communication-delay. By exploiting the passivity property of the decomposition and scattering-based communication, energetic passivity of the closed-loop system can be ensured, thus, interaction stability and safety are improved significantly. In a companion paper [1], simulation and semi-experiment (i.e. real master and simulated slaves) are performed to illustrate properties of this proposed framework.