Compensating the Effect of Communication Delay in Client-Server-based Shared Haptic Virtual EnvironmentsCompensating the Effect of Communication Delay in Client-Server-based Shared Haptic Virtual Environments

Compensating the Effect of Communication Delay in Client-Server-based Shared Haptic Virtual Environments

Shared Haptic Virtual Environments can be realized using a client-server architecture. In this architecture, each client maintains a local copy of the virtual environment (VE). A centralized physics simulation running on a server calculates the object states based on haptic device position information received from the clients. The object states are sent back to the clients to update the local copies of the VE, which are used to render interaction forces displayed to the user through a haptic device.

Communication delay leads to delayed object state updates and increased force feedback rendered at the clients. In the work presented in [1], we analyze the effect of communication delay on the magnitude of the rendered forces at the clients for cooperative multi-user interactions with rigid objects. The analysis reveals guidelines on the tolerable communication delay. If this delay is exceeded, the increased force magnitude becomes haptically perceivable. We propose an adaptive force rendering scheme to compensate for this effect, which dynamically changes the stiffness used in the force rendering at the clients. Our experimental results, including a subjective user study, verify the applicability of the analysis and the proposed scheme to compensate the effect of time-varying communication delay in a multi-user SHVE.

[1]
C. Schuwerk, X. Xu, R. Chaudhari, E. Steinbach,
Compensating the Effect of Communication Delay in Client-Server-Based Shared Haptic Virtual Environments,
ACM Transactions on Applied Perception, vol. 13, no. 1, pp. 1-22, December 2015.
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Selected Results

The Jenga game used for evaluation of the delay compensation scheme proposed in [1]. (a), (b) and (c) illustrate the interactions in the following figures (Figure adopted from [1]).
Magnitude of the rendered forces (left) and the stiffness (right) at client 1 and client 2 during interaction (a) in the above figure with zero communication delay (1), in the presence of constant communication delay (2) and with delay compensation enabled (3) (Figure adopted from [1])
Rendered forces (left) during interaction (b) in the above figure with the stiffness (right) at the clients. Zero communication delay (1), in the presence of simulated time-varying communication delay without delay compensation (2) and delay compensation enabled (3) (Figure adopted from [1]).
Rendered forces (left) during interaction (c) in the above figure with simulated time-varying delay (right) at the clients. Zero communication delay (1), in the presence of time-varying communication delay without delay compensation (2) and with delay compensation enabled (3) (Figure adopted from [1]).

Video

The following short video gives some details about the application used to evaluate the proposed schemes and the experimental setup used for the subjective evaluation.