Passive Shared Virtual Environment for Distributed Haptic Cooperation

For distributed haptic cooperation systems, this paper develops a framework for virtual environments such that the design of the coordinating controllers is decoupled from the network topology and the communication issues. The discrete-time n-port passivity of the shared virtual object (SVO) is presented when n SVO copies are distributed on an undirected and connected communication topology with unreliable data transmission. Wave nodes as passive network elements can be implemented on multilateral wave-based communication architecture to passively distribute power across the network. In this note, the wave node scheme introduced in [16] is employed to construct a passive wave-based network architecture in order to passively interconnect multiple discrete-time port-Hamiltonian local SVO copies alongside their coordinating controllers. The performance analysis shows that the proposed network architecture: (i) possesses n-port passivity over a network with time-varying delay and packet-loss; (ii) is lossless when subjected to communications with no time delay; and (iii) offers less dissipation comparing to the network structures built based on the node scheme proposed in [18]. Simulations in which a VO is shared among four peers across a network with constant and varying time-delay validate the analysis.