Method and device for measuring the position and orientation of objects in the presence of interfering metals
First Claim
1. A sensing device for determining the position and orientation of an object in a predefined space, comprising:
- a magnetic field generation means for generating a magnetic field having a rotating field vector, the field generation means situated in the predefined space at a known location and in a known orientation;
a first sensor means for sensing the rotating field vector and generating a signal in response to the rotating field vector, the first sensor means attached to the object whose position is being sensed;
a second sensor means for sensing the rotating field vector and generating a signal in response to the rotating field vector, the second sensor means attached to the object whose position is being sensed;
a timing means attached to the transmitting means and the first sensor means for sensing a first time period in which the rotating field vector travels between a reference point and the first sensor means, the timing means being further attached to the second sensor means for measuring a second time period in which the rotating magnetic field vector travels between the reference point and the second sensor means; and
a computing means for computing the position of the first sensor means based upon the first time period and for computing the position of the second sensor means based upon the second time period, the computing means for further computing the orientation of the object based upon the position of the first sensor means and the second sensor means.
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Accused Products
Abstract
A method of measuring the position and orientation of an object is disclosed in conjunction with an apparatus to achieve this method. The method and apparatus reduce the metal effects caused by metal objects which are in close proximity to a magnetic field generator. The metal effects are reduced by utilizing a magnetic field generator which creates a rotating magnetic field vector and then measuring the time required for that magnetic field vector to travel between a known reference point and the sensor whose position is being measured. By keeping the frequency of the rotating magnetic field vector constant and measuring the time required for this magnetic field vector to travel the previously mentioned distance, an angle between a reference axis and a vector directed toward the sensor can be determined. Once appropriate angles are measured, calculations can be undergone to determine the position of the sensor. Furthermore, by utilizing a plurality of sensors the orientation of the sensors with respect to one another can be determined.
82 Citations
27 Claims
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1. A sensing device for determining the position and orientation of an object in a predefined space, comprising:
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a magnetic field generation means for generating a magnetic field having a rotating field vector, the field generation means situated in the predefined space at a known location and in a known orientation; a first sensor means for sensing the rotating field vector and generating a signal in response to the rotating field vector, the first sensor means attached to the object whose position is being sensed; a second sensor means for sensing the rotating field vector and generating a signal in response to the rotating field vector, the second sensor means attached to the object whose position is being sensed; a timing means attached to the transmitting means and the first sensor means for sensing a first time period in which the rotating field vector travels between a reference point and the first sensor means, the timing means being further attached to the second sensor means for measuring a second time period in which the rotating magnetic field vector travels between the reference point and the second sensor means; and a computing means for computing the position of the first sensor means based upon the first time period and for computing the position of the second sensor means based upon the second time period, the computing means for further computing the orientation of the object based upon the position of the first sensor means and the second sensor means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sensing device for determining the position of an object in a space, comprising:
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a transmitting means for generating a plurality of rotating magnetic field vectors which rotate at a predetermined frequency, the transmitting means situated in at a known position; means for sensing a magnetic field vector, the sensing means attached to the object who'"'"'s position is being determined, the sensing means having an output for outputting a sensor signal indicative of the sensed magnetic fields; timing means for measuring a plurality of time duration required for the plurality of rotating field vectors to travel between a plurality of known reference points and the sensing means; and computing means for computing the position of the sensing means based upon plurality of measured time duration. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of determining the position of an object in a space comprising the steps of:
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generating a first rotating magnetic field using a magnetic field generator located at a known position, the first rotating magnetic field vector having a first magnetic field vector rotating at a predetermined frequency in a first plane; measuring the time period required for the first magnetic field vector to travel from a known first reference point to a sensor, the sensor being attached to the object who'"'"'s position is being determined; calculating a first angle in the first plane between a vector directed from the magnetic field vector to the first known reference point and a vector directed from the magnetic field generator to the sensor; generating a second rotating magnetic field using the magnetic field generator, the second rotating magnetic field having a second magnetic field vector rotating at a predetermined frequency in a second plane; measuring the time period required for the second magnetic field vector to travel from a known second reference point to the sensor; calculating a second angle in the second plane between a vector directed from the magnetic field vector to the second known reference point and a vector directed from the magnetic field generator to the sensor; generating a third rotating magnetic field using the magnetic field generator, the third rotating magnetic field having a third magnetic field vector rotating at a predetermined frequency in a third plane; measuring the time period required for the third magnetic field vector to travel from a known third reference point to the sensor; calculating a third angle in the third plane between a vector directed from the magnetic field vector to the third known reference point and a vector directed from the magnetic field generator to the sensor; and calculating the position of the object with respect to the magnetic field generator using the first angle, the second angle, and the third angle. - View Dependent Claims (18, 19, 20)
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21. A position sensing device for determining the position of a sensor in a space, comprising:
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magnetic field generation means for generating a plurality magnetic fields, the plurality of magnetic fields related such that they combine to form a plurality of rotating magnetic field vectors, the magnetic field generation means further having means for producing a reference signal indicative of the time at which the plurality of rotating magnetic field vectors pass through a predefined reference point; magnetic field receiver means for sensing the plurality of magnetic fields and providing a sensor signal indicative of the magnitude of the sensed magnetic fields; timing means attached to the receiver means to receive the sensor signal and interpret the sensor signal to determine when the rotating magnetic field vector intersects with the receiver means, the timing means also attached to the field generation means for receiving the reference signal, the timing means for determining the time period between the reference signal and a time at which the sensor signal indicates the detection of a rotating magnetic field vector; and computing means for determining the angular relationship between the transmitter means, the predefined reference point, and the receiver means. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification