Request-and-respond approach to reducing latency within a tracking system

Abstract

A method of managing latency in a system for tracking movement of an object includes providing a request-and-response mechanism for transferring tracking data across a communications link. In one embodiment, the object for which movement is to be tracked is a human head and the system is a virtual reality system. Packets of the tracking data may be generated using a conventional sensor processing technology, but the packets are transferred via the communications link to an image processing capability, such as that of a host computer. The packets are generated at a fixed sample rate that is asynchronous with respect to the processing requirements of the host computer. When the host computer is available for fresh tracking data, a packet-transfer request is transmitted to the source of the packet. Latency can be reduced by enabling the source of the packets to anticipate reception of a packet-transfer request. Thus, any incoming signal to the source is “prematurely” interpreted as a packet-transfer request. Appropriate actions are executed, if the interpretation is subsequently determined to be inaccurate. As a technique for reducing variability of latency, each transfer of a packet is preceded by a determination of whether to transmit a presently available packet or a next available packet. If a request is received momentarily before the next available packet is accessible, the presently available packet may be identified as “stale,” and the next packet may be transmitted when available.