Virtual Coupling Schemes for Position Coherency in Networked Haptic Environments

In networked haptic environments, multiple users remotely collaborate sharing the same virtual space. Such environments are used in surgical simulation training, maintenance task training, etc. Maintaining position coherency between the copies of the virtual object in these environments is necessary to achieve consistency in collaboration, especially in the presence of time delays between users. Client-server architecture is widely used to maintain position coherency in networked haptic environments. Such methods introduce a round trip delay for each user and also the collaboration depends on the client's ability to maintain communication with the server. In peer-to-peer architecture where the information from each user is multicasted to all other users, time delay is reduced to half compared to client-server based methods. It is also the most difficult method for maintaining position coherency. Of the three virtual coupling schemes introduced to maintain position coherency in this paper, two utilize a peer-to-peer architecture. The performance of the schemes using peer-to-peer architecture for constant time delays was compared to the virtual coupling scheme representing the client-server method. Experimental results demonstrate that one of the virtual coupling schemes has a comparable performance to the server-based method