Delay Compensation in Shared Haptic Virtual Environments

Shared Haptic Virtual Environments (SHVEs) are often realized us-ing a client-server architecture. At the server, a physics simulation engine calculates the object states based on the position informa-tion received from the clients. At the clients, the object state infor-mation, received from the server, is used to update the local copy of the virtual environment. Forces displayed to the user through a haptic device are computed locally at the client based on the in-teractions with the objects. Communication delay leads to delayed object state updates and increased interaction forces rendered at the clients. Users perceive this as increased object weight. In this pa-per, we systematically analyze the loss of transparency caused by communication delay and propose a novel adaptive force rendering scheme to compensate for it. The proposed scheme reduces the ob-jects ’ stiffness at the clients, based on delay, device velocity and motion constraints of the objects, only if necessary to achieve per-ceptual transparency. Simulations and subjective evaluations show that the effect of increased weight of objects is successfully com-pensated for the tested delay range of up to 150 ms. At the same time, if the object is unmovable, the perception of interaction with a rigid object is preserved