Abstract: A method and apparatus for reducing magnetic tracking error in the position and orientation determined in an electromagnetic tracking system is disclosed. In some embodiments, a corrected position and orientation is blended with an uncorrected position and orientation based upon the calculated probability of each. To determine a corrected position and orientation, data from an IMU in the receiver is used to obtain a constraint on the orientation. In other embodiments, the amount of detected error due to electromagnetic distortion is measured. Any error is first assumed to be from “floor distortion,” and a correction is applied. If the error is still deemed too great, a constraint is again obtained from IMU data. Using this constraint, another correction for the distortion is made. The solution from this correction may be blended with a standard solution and the solution from the floor distortion to arrive at a final solution.

Abstract: A system and method for performing synchronization of a magnetic field transmitter and receiver to resolve received signal phase ambiguity based upon the phases of the magnetic fields. Three orthogonal field frequencies are selected. A Fourier transform extracts the sine and cosine of the received signal, which provides the received signal phases and results in a complex signal matrix (“Sigmat”). A search is made for a phase rotation of the frequencies to achieve convergence of the Sigmat at a point it is real-valued; the search may be limited by aligning the Sigmat such that the major element becomes real-valued and rotating the other two frequencies. The correct phase is the one in which the Sigmat has a positive determinant and minimizes any remaining imaginary portion. A transmitter and receiver may be calibrated to account for any analog phase shift. Distortion of the magnetic field may also be detected and corrected.

Abstract: A system and method for performing synchronization of a magnetic field transmitter and receiver to resolve received signal phase ambiguity based upon the phases of the magnetic fields. Three orthogonal field frequencies are selected. A Fourier transform extracts the sine and cosine of the received signal, which provides the received signal phases and results in a complex signal matrix (“Sigmat”). A search is made for a phase rotation of the frequencies to achieve convergence of the Sigmat at a point it is real-valued; the search may be limited by aligning the Sigmat such that the major element becomes real-valued and rotating the other two frequencies. The correct phase is the one in which the Sigmat has a positive determinant and minimizes any remaining imaginary portion. A transmitter and receiver may be calibrated to account for any analog phase shift. Distortion of the magnetic field may also be detected and corrected.

Abstract: A method and apparatus for reducing magnetic tracking error in the position and orientation determined in an electromagnetic tracking system is disclosed. In some embodiments, a corrected position and orientation is blended with an uncorrected position and orientation based upon the calculated probability of each. To determine a corrected position and orientation, data from an IMU in the receiver is used to obtain a constraint on the orientation. In other embodiments, the amount of detected error due to electromagnetic distortion is measured. Any error is first assumed to be from “floor distortion,” and a correction is applied. If the error is still deemed too great, a constraint is again obtained from IMU data. Using this constraint, another correction for the distortion is made. The solution from this correction may be blended with a standard solution and the solution from the floor distortion to arrive at a final solution.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.

Abstract: A method and apparatus is disclosed for assisting a user, wearing a head mounted display (HMD) that covers a user's field of vision and has a tracker providing information regarding the position and orientation of the HMD, in locating a physical controller located on a physical base station. A processor causes the HMD to display a virtual world, including a virtual representation of the physical base station and physical controller along with a virtual hand that helps guide the user to the physical base station to allow the user to pick up the physical controller. Another embodiment allows an area in the physical world to be defined within which the user should remain, for example to avoid physical obstacles. The processor causes the HMD to display a warning, such as a virtual fence, to alert the user if the user approaches to within a preselected distance of the boundary.

Abstract: A method and apparatus is disclosed for assisting a user, wearing a head mounted display (HMD) that covers a user's field of vision and has a tracker providing information regarding the position and orientation of the HMD, in locating a physical controller located on a physical base station. A processor causes the HMD to display a virtual world, including a virtual representation of the physical base station and physical controller along with a virtual hand that helps guide the user to the physical base station to allow the user to pick up the physical controller. Another embodiment allows an area in the physical world to be defined within which the user should remain, for example to avoid physical obstacles. The processor causes the HMD to display a warning, such as a virtual fence, to alert the user if the user approaches to within a preselected distance of the boundary.

Abstract: A method and apparatus is disclosed for assisting a user, wearing a head mounted display (HMD) that covers a user's field of vision and has a tracker providing information regarding the position and orientation of the HMD, in locating a physical controller located on a physical base station. A processor causes the HMD to display a virtual world, including a virtual representation of the physical base station and physical controller along with a virtual hand that helps guide the user to the physical base station to allow the user to pick up the physical controller. Another embodiment allows an area in the physical world to be defined within which the user should remain, for example to avoid physical obstacles. The processor causes the HMD to display a warning, such as a virtual fence, to alert the user if the user approaches to within a preselected distance of the boundary.

Abstract: A method and apparatus is disclosed for assisting a user, wearing a head mounted display (HMD) that covers a user's field of vision and has a tracker providing information regarding the position and orientation of the HMD, in locating a physical controller located on a physical base station. A processor causes the HMD to display a virtual world, including a virtual representation of the physical base station and physical controller along with a virtual hand that helps guide the user to the physical base station to allow the user to pick up the physical controller. Another embodiment allows an area in the physical world to be defined within which the user should remain, for example to avoid physical obstacles. The processor causes the HMD to display a warning, such as a virtual fence, to alert the user if the user approaches to within a preselected distance of the boundary.

Abstract: A method and apparatus for self-relative body tracking in virtual reality systems using magnetic tracking is disclosed, which allows more accurate tracking of a user's body relative to the user's field of vision. A head-mounted magnetic tracking (HMMT) system is used, in which other parts of a user's body are tracked relative to the HMD on the user's head, rather than relative to a base station. This results in less distortion of the magnetic field used for tracking and thus allows for more accurate determination of the position and orientation of a user's body parts relative to the user's field of vision, so that a more accurate avatar may be presented on the HMD to the user. This allows the avatar of the user's body part to be shown in a location that corresponds closely to its physical position. In an alternative embodiment, multiple portions of the user's body may be tracked.