Penumbra, Inc.

Ran Bar-On

Ron Barak

Alejandro Santiago Diaz

Oded Y Zur

Michael D Collins

Amir Rubin

Cameron J Mahon

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.

Method and apparatus for reducing magnetic tracking error

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.

Method and apparatus for phase-based synchronization in magnetic tracking systems

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Tel Aviv, Israel

Ran Bar-On