Method for calculating relative phases between signal channels in a multi-sensor tracking device

Abstract

Disclosed is a method for calculating relative phase between channels of a multi-sensor tracking device. The relative phases may be used to calibrate the multi-tracking sensor device to perform more accurately. The method involves recording a plurality of first signals generated by a first channel of the multi-sensor tracking device. The plurality of first signals are generated during a movement of the multi-sensor tracking device. Typically, the multi-sensor tracking device includes several channels, each one of which includes at least one sensor for sensing movement with respect to a corresponding axis. Concurrent to recording of plurality of first signals, a plurality of second signals generated by a second channel of the multi-sensor tracking device, is recorded. The plurality of second signals are generated during the movement of the multi-sensor tracking device. Thereafter, a relative phase between the first and second channels is calculated as a function of the recorded plurality of first signals and the recorded plurality of second signals.

What is claimed is:  
     
         1 . A method of calibrating a device comprising first and second motion sensors coupled to first and second circuits, respectively, the method comprising: 
 the first motion sensor generating a first motion sensor signal during a movement of the device, wherein the first motion sensor generates signals only during movement of the device in a first direction;    a second motion sensor of the device generating a second motion sensor signal during the movement of the device, wherein the second motion sensor generates signals only during movement of the device in a second direction, wherein the first and second directions are orthogonal to each other;    a first circuit receiving the first motion sensor signal and generating a first circuit signal in response to receiving the first motion sensor signal;    a second circuit receiving the second motion sensor signal and generating a second circuit signal in response to receiving the first motion sensor signal;    calculating a time difference between the time the first circuit generates the first circuit signal and the time the second circuit generates the second circuit signal.    
     
     
         2 . An apparatus comprising: 
 a first motion sensor fixedly connected to a device, wherein the first motion sensor generates a first motion sensor signal during a movement of the device, wherein the first motion sensor generates signals only during movement of the device in a first direction;    a second motion sensor fixedly connected to a device, wherein the second motion sensor generates a second motion sensor signal during the movement of the device, wherein the second motion sensor generates signals only during movement of the device in a second direction, wherein the first and second directions are orthogonal to each other;    a first circuit coupled to the first motion sensor, wherein the first circuit generates a first circuit signal in response to receiving the first motion sensor signal from the first motion sensor;    a second circuit coupled to the second motion sensor, wherein the second circuit generates a second circuit signal in response to receiving the second motion sensor signal from the second motion sensor;    a data processing circuit coupled to the first and second circuits for calculating a time difference between the time the first circuit generates the first circuit signal and the time the second circuit generates the second circuit signal.    
     
     
         3 . A multi-sensor tracking device comprising: 
 a plurality of channels each one of which includes at least one sensor for sensing movement of the at least one sensor with respect to a corresponding axis, wherein the plurality of channels are configured to generate one or more signals in response to movement of the tracking device, and;    a processor in data communication with the plurality of channels, wherein the processor is configured to generate orientation signals relating a current orientation of the multi-sensor tracking device to a pre-determined point in space, wherein the processor is configured to generate the orientation signals as a function of one or more signals generated by the plurality of channels and one or more relative phases, wherein each relative phase is defined as a relative time lag between corresponding signals traveling through a pair of the plurality of channels.    
     
     
         4 . The multi-sensor tracking device of  claim 3  wherein the relative phases are stored therein, wherein the relative phases include a relative phase between a first and a second channel of the plurality of channels, wherein the relative phase between the first and second channels is calculated from a plurality of first signals generated by the first channel during a movement of the multi-sensor tracking device and a plurality of second signals generated by the second channel during the movement of the multi-sensor tracking device.  
     
     
         5 . The multi-sensor tracking device of  claim 4  wherein the relative phases include a relative phase between the second channel and a third channel and a relative phase between the first and third channels, wherein the relative phase between the second and third channels is calculated from the plurality of second signals and a plurality of third signals generated by the third channel during the movement of the multi-sensor tracking device, and wherein the relative phase between the first and third channels is calculated from the plurality of first signals and the plurality of third signals.  
     
     
         6 . A method comprising: 
 a plurality of channels of a multi-sensor tracking device generating one or more signals in response to movement of the a multi-sensor tracking device, wherein each one of the channels includes at least one sensor for sensing movement of the at least one sensor with respect to a corresponding axis    generating orientation signals as a function of the one or more signals generated by the plurality of channels and one or more relative phases, wherein each relative phase is defined as a relative time lag between corresponding signals traveling through a pair of the plurality of channels, wherein each orientation signal relates a current orientation of the multi-sensor tracking device to a pre-determined point in space.    
     
     
         7 . The method of  claim 6  wherein the relative phases include a relative phase between a first and a second channel of the plurality of channels, wherein the relative phase between the first and second channels is calculated from a plurality of first signals generated by the first channel during a movement of the multi-sensor tracking device and a plurality of second signals generated by the second channel during the movement of the multi-sensor tracking device.  
     
     
         8 . The method of  claim 7  wherein the relative phases include a relative phase between the second channel and a third channel and a relative phase between the first and third channels, wherein the relative phase between the second and third channels is calculated from the plurality of second signals and a plurality of third signals generated by the third channel during the movement of the multi-sensor tracking device, and wherein the relative phase between the first and third channels is calculated from the plurality of first signals and the plurality of third signals.