Moderating Simulation Lag in Haptic Virtual Environments

Simulation lag is a known issue in networked virtual environments where users are geographically distributed. When users collaborate across the network using haptics, there are always momentary lacks of synchronization due to packet delay, loss, and jitter. Many strategies exist for dealing with such scenarios, but these strategies concentrate on one aspect and don´t adequately address the necessary realism, causality, and the sense of co-presence in the virtual environments during closely-coupled haptic tasks. In this paper, we propose an approach that uses two techniques to moderate the simulation lag in haptic-based virtual environments. A decorator, which is a visual cue embedded in the haptic virtual object, is used to inform the user about the sate of simulation lag. In addition, this decorator is controlled by an algorithm that predicts the users´ most likely action in the very short term, and compensates delayed or lost packets by interpolating collaborative actions. In other words, this technique improvises the current state of the haptic virtual object and displays it to the local user, in addition to calculating the current network delay/loss and indicating it non-intrusively to the local user