Patent ID: 11016167

Abstract:
A tracking method includes displaying visual content on a screen of a head mounted display (HMD). One or more base stations may be stationary with respect to the screen while the visual content is being displayed. In contrast, one or more objects may move with respect to the screen while the visual content is being displayed. Time-difference-of-arrival (TDoA) and/or time-of-flight (ToF) may be measured for one or more ultrasonic pulses transmitted from the base station, one or more objects, or HMD. Position and orientation of the objects and HMD may be calculated based on the TDoA and ToF. Different frequencies of pulses may be used to locate the HMD and the objects. An electromagnetic synchronization signal from the HMD and/or base station may be used to measure TDoA. Position and orientation measurements may be fused with outputs from IMUS (inertial measurement units) to reduce jitter.