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.

A method and system for locating a sound source are provide. The method may include detecting a sound signal of a sound by each of two audio sensors. The method may also include converting the sound signals detected by the two audio sensors from a time domain to a frequency domain. The method may further include determining a high frequency ratio of each of the sound signals in the frequency domain. The method may further include determining a direction of the sound source based on the high frequency ratios.

A method and system for locating a sound source are provide. The method may include detecting a sound signal of a sound by each of two audio sensors. The method may also include converting the sound signals detected by the two audio sensors from a time domain to a frequency domain. The method may further include determining a high frequency ratio of each of the sound signals in the frequency domain. The method may further include determining a direction of the sound source based on the high frequency ratios.

Disclosed is a method for locating a portable device giving hands free access to a vehicle, by a location device intended to be installed in the vehicle, the portable device communicating with the location device by ultra high frequency waves, the invention consisting at each transmission of an ultra high frequency signal by the location device: of simultaneously transmitting by the location device at least one ultrasonic signal, intended for the portable device; of measuring a delay between a first time of reception of the ultra high frequency signal and un second time of reception of the ultrasonic signal by the portable device; of determining a distance between the portable device and the location device on the basis of the delay thus measured. Also disclosed is a location device and a corresponding portable device.

The present invention provides a method and system for real-time high-precision positioning in the deep sea. The present invention, based on a ray theory model, uses an azimuth angle, a transmission delay, a deep-sea vehicle depth and a depth of an acoustic transducer of a water surface monitoring platform as an eigenray emergence angle, an eigenray transmission time, eigenray emergence depth and an eigenray end point depth respectively, quickly calculates an eigenray that connects the water surface monitoring platform with the deep-sea vehicle, accurately calculates a position of the deep-sea vehicle relative to the water surface monitoring platform, and converts the position into absolute position information of the deep-sea vehicle through the latitude and longitude of the water surface monitoring platform, thereby achieving real-time high-precision positioning.

The present invention provides a method and system for real-time high-precision positioning in the deep sea. The present invention, based on a ray theory model, uses an azimuth angle, a transmission delay, a deep-sea vehicle depth and a depth of an acoustic transducer of a water surface monitoring platform as an eigenray emergence angle, an eigenray transmission time, eigenray emergence depth and an eigenray end point depth respectively, quickly calculates an eigenray that connects the water surface monitoring platform with the deep-sea vehicle, accurately calculates a position of the deep-sea vehicle relative to the water surface monitoring platform, and converts the position into absolute position information of the deep-sea vehicle through the latitude and longitude of the water surface monitoring platform, thereby achieving real-time high-precision positioning.

A system for human interaction with virtual objects comprises: a touch sensitive surface, configured to detect a position of a contact made on the touch sensitive surface; a reference layer rigidly attached to the touch sensitive surface and comprising one or more patterns; a display device, configured to display a virtual object that is registered in a reference coordinate fixed with respect to the touch sensitive surface; one or more image sensors rigidly attached to the display device, configured to capture an image of at least a portion of the one or more patterns; and at least one processor, configured to determine a position and an orientation of the display device with respect to the touch sensitive surface based on the captured image, and identify an interaction with the virtual object based on the detected position of the contact made on the touch sensitive surface.

A method comprises transmitting (901) a first ultrasonic ping signal from a first floating unit (M1). The first ultrasonic ping signal is received in an underwater device (D1, D2, D3). After a predetermined delay from the reception of the first ultrasonic ping signal, the underwater device transmits (905) a second ultrasonic ping signal from the underwater device. The second ultrasonic ping signal is received in the first floating unit. The first floating unit determines a time difference between a time of transmission of the first ultrasonic ping signal from the first floating unit and a time of reception of the second ultrasonic ping signal, and based on the time difference, provides location information and/or other information to the underwater device by transmitting (910) to the underwater device sequential underwater ultrasonic ping signals such that time differences between the sequential underwater ultrasonic ping signals indicate the provided information.

A method comprises transmitting (901) a first ultrasonic ping signal from a first floating unit (M1). The first ultrasonic ping signal is received in an underwater device (D1, D2, D3). After a predetermined delay from the reception of the first ultrasonic ping signal, the underwater device transmits (905) a second ultrasonic ping signal from the underwater device. The second ultrasonic ping signal is received in the first floating unit. The first floating unit determines a time difference between a time of transmission of the first ultrasonic ping signal from the first floating unit and a time of reception of the second ultrasonic ping signal, and based on the time difference, provides location information and/or other information to the underwater device by transmitting (910) to the underwater device sequential underwater ultrasonic ping signals such that time differences between the sequential underwater ultrasonic ping signals indicate the provided information.

A tracking method is disclosed. The method may include displaying visual content on a screen. A base station 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. The one or more objects may be tracked so that the movement thereof may be used to alter the visual content. Such tracking may involve the base station and the one or more objects sending and/or receiving one or more ultrasonic pulses. Time-difference-of-arrival and/or time-of-flight of the one or more ultrasonic pulses may then be used to estimate a relative location and/or a relative orientation of the one or more objects with respect to the base station in three dimensional space.