Transparent Data Reduction in Networked Telepresence and Teleaction Systems. Part II: Time-Delayed Communication

Two of the major challenges in networked haptic telepresence and teleaction systems are the time delay associated with the data transmission over the network and the limited communication resources. Sophisticated control methods are available for the stabilization in the presence of time delay. The reduction of haptic network traffic, however, is only poorly treated in the known literature. Data reduction approaches for time delayed haptic telepresence are not available at all. This article presents a novel approach to reduce the network traffic in haptic telepresence systems with constant (unknown) time delay. With the proposed deadband control approach data are sent only if the signal to transmit changes more than a given threshold value. In order to guarantee stability with time delay and data reduction a well-known time delay approach, the scattering transformation, is extended. Experimental user studies show that an average network traffic reduction up to 96 is achieved without significantly impairing the perception of the remote environment compared to the standard approach with time delay.