Transparency in Port-Hamiltonian Based Telemanipulation

Abstract

Stability is a key issue in the implementation of a bilateral telemanipulation system since both the non-negligible time delay in the communication between master and slave and the interaction with unknown environments can destabilize the whole system. In Chap. 4 it has been shown that passivity theory and port-Hamiltonian systems can be fruitfully used to build an intrinsically passive telemanipulation scheme which, therefore, has a stable behavior both in case of free motion and in case of contact with any passive, possibly unknown, environment. Scattering theory has been used to build a communication channel which is lossless independently of any constant transmission delay and the problem of wave reflection arising when coupling master and slave side through scattering based communication channels has been solved. The scheme has been extended in order to take into account the sampled data nature of controllers in a passive way. Moreover discrete scattering has been defined and packet-switching transmission lines have been considered. A communication strategy that allows to preserve passivity even in case of loss of packets and of variable transmission delay has been proposed. Finally, a passivity preserving algorithm that allows to rebuild lost packets by interpolation has been proposed.