Bilateral Energy Transfer for high fidelity Haptic Telemanipulation

Among the methods to grant the stability of a telemanipulation system, the bilateral time domain passivity framework has the appealing characteristic to consider both, force and velocity signals exchanged between master and slave systems, and the power introduced or dissipated by the elements that compose the telemanipulation system. In previous works, [2, 3], it has been shown how the bilateral passivity controller (BiPC) can preserve stability when the communication channel that conveys data between master and slave is affected by delay. In this work the authors intend to further explore the possibilities offered by the Bilateral Energy Transfer concept as design guideline, and to refine the control schemes already discussed in [3]. The underlying idea of the Bilateral Energy Transfer is to achieve a transport of energy between the two sides of the real system as faithful to an "ideal" (not delayed) system as allowed by the energy leaks. As energy leak is meant the behavior introduced by the not ideality of some components, such as the communication channel. At the same time, in order to obtain easy-to-use system, the control system must preserve, in some extend, the force, velocity, and position correspondences between master and slave. In order to achieve this goal, a modified version of passivity controller is presented. Its main characteristic is that its correction action aimed at dissipating energy, regarded as generated by energy leaks, is limited and deferred in time. Moreover, a drift compensator is introduced whose role is to solve a drift in position introduced by the operation of the same BiPC; in order to maintain the whole system passive, the action of this controller is bounded to the amount of energy that has been dissipated in excess by the BiPC.