Method And Apparatus For Synchronizing a Transmitter and Receiver in a Magnetic Tracking System

摘要

A method and apparatus is disclosed for synchronizing a magnetic field transmitter and receiver to resolve phase ambiguity so that phase information for the position and orientation of the receiver may be derived and maintained. A synchronization process allows for the phase information to be initially derived based upon known information from other sources, and then tracked from one measurement to the next. In another embodiment, information from an inertial measurement unit (IMU) is used to determine the phase information or to correct for errors in the determination from receiver data of the position and orientation of a receiver, and prevent such errors from accumulating as the receiver moves away from a transmitter.

主权项

1. A method of synchronizing a transmitter and receiver in a magnetic tracking system to properly determine a position and orientation of the receiver relative to the transmitter, the transmitter comprising a plurality of source magnetic coils each configured to generate a magnetic field, and the receiver comprising a plurality of sensor magnetic coils configured to sense the magnetic fields and to generate a signal matrix representing the position and orientation of the receiver relative to the transmitter, the method comprising:
receiving at a processor the signal matrix from the receiver; creating by the processor an unsigned version of the signal matrix containing amplitudes indicating the distance of the receiver from the transmitter but not containing phase signs indicating the position and orientation of the receiver relative to the transmitter; applying by the processor one of a plurality of possible phase sign combinations to the unsigned signal matrix to create a first signed signal matrix; determining by the processor whether the first signed signal matrix is one of a plurality of expected signal matrices, each expected signal matrix having phase signs and representing the position and orientation of a known location relative to the transmitter; if the first signed signal matrix is one of the plurality of signed signal matrices, saving by the processor the phase signs of the first signed signal matrix as indicating the position and orientation of the receiver relative to the transmitter; if the first signed signal matrix is not one of the plurality of signed signal matrices, applying by the processor another one of the plurality of possible phase sign combinations to the unsigned signal matrix to create a second signed signal matrix; determining by the processor whether the second signed signal matrix is one of the plurality of expected signal matrices; and if the second signed signal matrix is one of the plurality of signed signal matrices, saving by the processor the phase signs of the second signed signal matrix as indicating the position and orientation of the receiver relative to the transmitter.