JP2009047470A - Magnetic three-dimensional position detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic three-dimensional position detection device capable of estimating highly accurately the position or the direction of a reception coil by measured values or calibration magnetic field data which are few compared with hitherto, even when a distance between a transmission coil and the reception coil is short. <P>SOLUTION: In this magnetic three-dimensional position detection device which is a device for generating AC magnetic fields having each mutually different frequency from a plurality of transmission coils, and measuring a three-dimensional position of the reception coil by using a reception signal induced into the reception coil, magnetic field intensity induced into the reception coil is determined from a magnetic field intensity function showing a space pattern of the magnetic field intensity using a magnetic dipole model in consideration of the size of the transmission coil relative to the AC magnetic field generated from the transmission coil, and the position and the direction of the reception coil are measured by a means for calculating the three-dimensional position and direction of the reception coil so that an error between signal intensity predicted from the magnetic field intensity function and signal intensity measured actually by the reception coil becomes minimum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic three-dimensional position detection apparatus and a detection method that determine a three-dimensional position of a receiving coil by inducing an electric signal to the receiving coil by a magnetic field generated from the transmitting coil.

2. Description of the Related Art Conventionally, a position detection device that induces an electrical signal to a receiving coil by an alternating magnetic field generated from a transmitting coil and detects a three-dimensional position of the receiving coil based on the intensity of the received signal has been used.
In these devices, in order to obtain the spatial position information of the receiving coil from the received signal, the intensity of the received signal is expressed as a magnetic field function with respect to the relative positional relationship between the transmitting coil and the receiving coil. . For such a magnetic field function, a physical formula based on electromagnetic theory relating to the magnetic field generated by the transmission coil is used (for example, see Non-Patent Document 1).
The three-dimensional position of the receiving coil is determined so that the error between the received signal predicted from the magnetic field function and the actually measured signal strength is minimized.

In addition, there is a method for obtaining a magnetic field strength function by arranging reception coils at a plurality of positions in a magnetic field and complementing the measurement data of the magnetic field strength of these reception coils by spline (see, for example, Non-Patent Document 2). .
Atoda, Nakamura, Serizawa, Yokoyama, Imada, “A Design Method of Dipole Arrangement and Coordinate Back-Calculation Algorithm in Magnetic Motion Capture Device”, Society of Instrument and Control Engineers, Vol. 34, no. 5,445-453, 1998 Kashiwagi, Wakamiya, Mochida, "Evaluation of three-dimensional magnetic sensor system", IEICE Technical, SP2005-55, 2005

As in Non-Patent Document 1 described above, a magnetic dipole model that ignores the size of the transmission coil has been used as a magnetic field strength function that represents a spatial pattern of the intensity of the alternating magnetic field generated from the transmission coil. .
This magnetic dipole model is established when the distance between the transmission coil and the reception coil is sufficiently larger than the size of the transmission coil. However, in practice, this assumption may not be satisfied because the receiving coil may be arranged at a distance several times the size of the transmitting coil.
Therefore, the method of Non-Patent Document 1 has a problem that it is difficult to accurately estimate the position and orientation of the receiving coil if the assumed magnetic field strength function does not match the actual magnetic field strength pattern. .

Further, since the method of Non-Patent Document 2 does not use the magnetic dipole model, it is effective even when the transmitting coil and the receiving coil are close to each other.
However, in the method of Non-Patent Document 2, it is necessary to measure magnetic field strength data so as to cover the entire measurement range, and thus there is a problem that it takes a lot of time to measure magnetic field data for calibration of the magnetic field strength function. It was.

  The present invention has been made in view of such circumstances, and even if the distance between the transmission coil and the reception coil is short, the position and orientation of the reception coil can be determined by using less measurement values and magnetic field data for calibration than in the past. It is an object of the present invention to provide a magnetic three-dimensional position detection device that can be estimated with high accuracy.

  The magnetic three-dimensional position detection apparatus of the present invention generates AC magnetic fields having different frequencies from a plurality of transmission coils, and further uses the received signal induced in the reception coil to determine the three-dimensional position of the reception coil. A magnetic three-dimensional position detecting device for measuring, and for an alternating magnetic field generated from the transmission coil, a magnetic field strength spatial pattern (in other words, a space pattern) using a magnetic dipole model in consideration of the size of the transmission coil. A predicted value calculation unit for obtaining a magnetic field strength induced in the receiving coil by a magnetic field strength function representing a typical magnetic field strength pattern), a signal strength predicted from the magnetic field strength function, and an actual measurement by the receiving coil Error minimizing means for calculating the three-dimensional position and orientation of the receiving coil so that an error from the received signal strength is minimized, and the reception by the result of the error minimizing means. And a position detector for measuring the position and orientation of yl.

  In the magnetic three-dimensional position detection apparatus of the present invention, the magnetic dipole model represents a magnetic field strength function including position information of both ends of the transmission coil where magnetic charges are arranged.

  The magnetic three-dimensional position detection method of the present invention generates AC magnetic fields having different frequencies from a plurality of transmission coils, and further uses the received signal induced in the reception coil to determine the three-dimensional position of the reception coil. A magnetic three-dimensional position detection method for measuring, wherein a predicted value calculation unit uses a magnetic dipole model in consideration of the size of the transmission coil for an alternating magnetic field generated from the transmission coil. A magnetic field strength function that represents the magnetic field strength induced in the receiving coil, a signal strength that the error minimizing means predicts from the magnetic field strength function, and a signal strength that is actually measured by the receiving coil. And a process of calculating the three-dimensional position and orientation of the receiving coil so that the error between the receiving coil and the position of the receiving coil is determined by the result of the error minimizing means. And a process for measuring the can.

  The magnetic three-dimensional position detection method of the present invention is characterized in that the magnetic field strength function is represented by the magnetic dipole model considering position information of both ends of the transmission coil where magnetic charges are arranged.

The program of the present invention is a computer-executable program for causing a computer to execute any one of the magnetic three-dimensional position detection methods described above.
The recording medium of the present invention is a computer-readable recording medium on which the above program is recorded.

As described above, the magnetic three-dimensional position detection apparatus of the present invention takes into account the size of each transmission coil when estimating the signal strength induced in the reception coil, and therefore the both ends of the transmission coil. Can be reflected in the prediction of the signal strength.
For this reason, in the magnetic three-dimensional position detection apparatus of the present invention, since it is used when estimating the position information of both ends of the transmission coil, it is estimated by ignoring the size of the transmission coil as in the prior art. Compared to the case, the spatial pattern of the magnetic field strength can be expressed with high accuracy.
Therefore, according to the magnetic three-dimensional position detection apparatus of the present invention, the position and orientation of the receiving coil are estimated based on the magnetic field strength function representing the magnetic field strength pattern in consideration of the positions of both ends of the transmitting coil. Therefore, it is possible to improve the accuracy of the position estimation of the receiving coil.
Further, according to the magnetic type three-dimensional position detection apparatus of the present invention, the magnetic field data for calibration required for the configuration of the magnetic field strength function is compared with the conventional method of expressing the magnetic field strength pattern by spline interpolation of the magnetic field data. The number can be greatly reduced.

<Outline of the present invention>
The present invention generates an alternating magnetic field having a different frequency from each of a plurality of transmission coils, and uses a reception signal induced in a reception coil that is a detection target to measure the three-dimensional position of the reception coil. It relates to a three-dimensional position detection apparatus, and for an alternating magnetic field generated from a transmission coil, a magnetic dipole model that takes into account the size of each transmission coil (positions at both ends of the transmission coil where the magnetic pole exists) is used. The magnetic field strength function representing the spatial pattern of the magnetic field strength is used to determine the magnetic field strength induced in the receiving coil, and there is an error between the signal strength predicted from the magnetic field strength function and the signal strength actually measured by the receiving coil. Means for calculating the three-dimensional position and orientation of the receiving coil and measuring the position and orientation of the receiving coil by this means so as to be minimized.

As described above, the present invention reduces the size of the transmission coil by using the spatial pattern of the magnetic field strength of the alternating magnetic field generated from the transmission coil using the position coordinates of both ends where the magnetic charge of the transmission coil exists. It is represented by a magnetic dipole model that takes into account.
Thus, in the magnetic dipole model according to the present invention, it is considered that magnetic charges having different polarities are arranged at both ends of the axis of the transmission coil (axis around which the coil is wound).
On the other hand, the size of the receiving coil is assumed to be sufficiently smaller than that of the transmitting coil, and this is regarded as a point in the space having no size.

The strength of the magnetic field generated at the position where the receiving coil is present is expressed by the magnitude of the magnetic charge at both ends of the transmitting coil and the relative position of the receiving coil with respect to the magnetic charge located at both ends.
Therefore, in the present invention, since both end positions of the transmission coil are reflected in the magnetic field strength function, in the magnetic three-dimensional position detection device, in order to improve measurement accuracy in relation to the transmission coil and the reception distance. In addition, the size of the transmission coil can be considered.

Furthermore, the present invention uses the magnetic field strength function that reflects the size of the transmission coil as described above, so that the position of the reception coil and the inclination (direction of magnetic field lines) with respect to the direction of the magnetic field generated by the transmission coil (the direction of the magnetic lines) will be described later. φ) is an unknown variable, and the intensity of the signal induced in the receiving coil can be predicted or estimated.
That is, the position and orientation of the receiving coil are estimated by determining the values of these unknown variables so that the error between the predicted value of the signal strength and the actually measured signal strength is minimized. .

In the present invention, as described above, the receiving coil is assumed to have no size. Therefore, it is necessary to sufficiently reduce the size of the receiving coil so that this assumption is satisfied.
Therefore, in the present invention, a single-axis coil that is easy to miniaturize is used as a receiving coil for position detection.
Further, in the present invention, five or more transmission coils are used, and for these five or more magnetic field components, the square error between the predicted value of the signal strength and the actually measured received signal strength is minimized. Thus, it is possible to detect the position and orientation of the single-axis receiving coil.

In the present invention, since the magnetic field strength function indicating the spatial pattern of the magnetic field strength is expressed using a physical magnetic dipole model, the parameter included in the model is only the gain term of the scalar quantity.
For this reason, the present invention can extremely reduce the number of parameters to be calibrated in advance as compared with the method of representing the magnetic field strength function by spline interpolation in the conventional example.
Therefore, in the present invention, since the number of magnetic field data for calibration for calibrating the magnetic field strength function is small, even when a plurality of receiving coils are used for position detection, there is a problem that it takes a long time for calibration. Absent.

<Embodiment>
Hereinafter, a magnetic three-dimensional position detection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a magnetic three-dimensional position detection apparatus according to the embodiment.
The magnetic three-dimensional position detection apparatus of the present embodiment includes a transmission coil (S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ ) that applies an alternating magnetic field to a reception coil to be detected, and the transmission Transmit coil drive unit 1 for generating alternating magnetic fields of different frequencies for the coils, receiving coil D, and the intensity of the received signal induced in the receiving coil D by the alternating magnetic field is detected and detected for each frequency. A detection unit 2 that outputs a signal; a predicted value calculation unit 3 that calculates a predicted value of the received signal by a magnetic field strength function set for each transmission coil; and a minimum signal error between the detected value and the detected value And an error minimizing unit 4 for performing the calculation, and a position detecting unit 5 for obtaining the position of the transmitting coil from the result obtained by the error minimizing unit.

Next, the operation of detecting the position and inclination of the receiving coil in the magnetic three-dimensional position detection apparatus according to the present embodiment will be described with reference to FIGS. FIG. 2 shows a procedure for calculating the position and orientation of the receiving coil from the intensity of the signal induced in the receiving coil by generating an alternating magnetic field by the transmitting coil in the magnetic three-dimensional position detection apparatus according to the present embodiment. It is a flowchart which shows. FIG. 3 is a conceptual diagram for explaining the operation of the magnetic three-dimensional position detection device according to the present embodiment. FIG. 3A shows transmission coils S ₁ , S ₂ , S ₃ , S in the magnetic three-dimensional position detection device. ₄ , S ₅ , and S ₆ are examples of arrangement, and FIG. 3B is a conceptual diagram illustrating a method of representing the position and orientation of the receiving coil D.

In the arrangement example in FIG. 3A, in the six transmission coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ , alternating magnetic fields having different frequencies are controlled by the control of the transmission coil driving unit 1. Is generated.
In FIG. 3B, x, y, and z are defined as coordinate axes for representing the position of the receiving coil D. The angles θ ₁ and θ ₂ in FIG. 3B represent the rotation angle with the y axis as the rotation axis and the rotation angle with the z axis as the rotation axis, respectively.
In the present embodiment, it is necessary to predict the strength of the received signal when the position and inclination of the receiving coil D are given.

For this reason, it is necessary to express the spatial pattern of the intensity of the alternating magnetic field generated from the transmission coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ as a magnetic field strength function using a magnetic dipole model. .
The magnetic field generated from each of the transmission coils SS ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ is an AC magnetic field. In this embodiment, for example, the transmission coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ are driven by an alternating current driven by the transmission coil driving unit 1 so that a sinusoidal alternating magnetic field is generated.
At this time, the generated magnetic field also changes sinusoidally. The amplitude of this sinusoidal time function is called the magnetic field strength, that is, the magnetic field strength in this embodiment. In the following description, the transmission coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ will be described as the transmission coil S _i .

In the magnetic dipole model used in the present embodiment, the magnetic field intensity is expressed by the following formula (1) as a vector h = (h _x , h _y , h _z ) ^T using the magnetic dipole model as follows. expressed.

Here, h _x , h _y , and h _z are components in the respective axial directions of the magnetic field strength, and G is determined by the magnitude (or strength) of magnetic charges at both ends of the transmission coil, the air permeability, and the like. It is a certain gain. T represents vector transposition.
Further, r _p and r _n are the positions X _p and X _n at both ends of the transmission coil S and the position X of one point in the three-dimensional (xyz) coordinate space, as shown in the following equation (2). Is a vector representing the relative relationship between

According to the above-described formulas (1) and (2), in the present embodiment, the position information of both ends of the transmission coil S where the magnetic charge is arranged is used, thereby taking the size of the transmission coil S into consideration. A magnetic field strength function can be represented.
Therefore, even when the distance between the transmission coil S and the reception coil D is not sufficiently large compared to the size of the transmission coil S (the distance between the magnetic poles at both ends), the actual magnetic field strength pattern is It can be expressed with higher accuracy than the conventional example.

The predicted value calculation unit 3 uses the above equations (1) and (2), and when there is a receiving coil D whose size can be ignored at a point X (x, y, z) in the three-dimensional coordinate space, For the AC magnetic field generated by the i-th transmission coil being driven by the transmission coil drive unit 1, the received signal strength u _i of the received signal (voltage value) induced in the receiving coil D is expressed by the following equation (3). The predicted value is calculated using this (step S3).

In the above equation (3), α is a gain inherent to the receiving coil D, h _i is the magnetic field strength vector, and φ _i is an angle formed by the axis of the receiving coil D and the magnetic field strength vector.
The relationship between the inclination (θ ₁ , θ ₂ ) of the receiving coil D and the angle φ _i is given as follows. In the above equation (3), | h _i | cosφ _i can be replaced with h _i · e. Here, “·” represents an inner product of vectors, and “e” is a vector of length 1. The vector e _{x 1} axial unit vector _e 1 = ^{(1,0,0) T,} the so obtained rotated at theta ₂ angle for theta _{1, x 3} axes for _{x 2} axis,
e = A ₃ A ₂ e ₁
It becomes. Here, each of A ₃ and A ₂ is a rotation matrix shown in the following equation (4).

That is, when the inclinations (θ ₁ , θ ₂ ) of the receiving coil are fixed to certain values, the rotation matrices A ₂ and A ₃ are obtained and the vector e is determined. By calculating the inner product of the vector e and the magnetic field strength h _i , the influence of the inclination (θ ₁ , θ ₂ ) of the receiving coil D on the magnetic field is taken into consideration.
In the above equation (3), if the gain G _i of the magnetic field strength function of α and the i-th transmission coil S _i is collectively expressed as G _i , the predicted value of the received signal strength is (5) It can represent with Formula.

In the above equation (5), r _pi and r _ni are expressed by the following equation (6).

In the above equation (5), X _pi and X _ni indicate the positions of both ends of the i-th transmission coil S _i , respectively. The gain G _i in the magnetic field strength function is an unknown number, but the magnetic field used to calibrate the measurement value by measuring the signal strength of the received signal that is induced by arranging the receiving coil D at a known position and orientation. Data can be created.
That is, the receiving coil D is arranged at the position and orientation for acquiring the magnetic field data, and the transmitting coil driving unit 1 receives alternating currents having different frequencies from the transmitting coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S _6. A magnetic field is generated and transmitted so that the signal strength of the received signal of the receiving coil D detected by the detection unit 2 matches the signal strength obtained by the magnetic field strength function using the position and orientation data of the receiving coil D. The gain G _i (1 ≦ i ≦ 6) of each coil S _i (1 ≦ i ≦ 6) is corrected.

If it is considered that the positions of both ends of the transmission coil S _i are fixed, r _pi and r _ni depend on the coordinates X (x, y, z) where the reception coil D exists, and φ _i is received. It depends on the coordinates X (x, y, z) of the coil D and the inclinations (θ ₁ , θ ₂ ) of the receiving coil D.
For this reason, when the predicted value calculation unit 3 calculates the predicted strength u _i using the magnetic field strength function, r _pi and r _ni corresponding to the coordinate X (x, y, z) and the coordinate X (x, y , Z) and φi corresponding to the inclinations (θ ₁ , θ ₂ ) of the receiving coil D are substituted to obtain the predicted intensity u _i .

Therefore, if the position or inclination of the receiving coil D changes, the signal intensity u _i predicted accordingly changes.
For example, the predicted value calculation unit 3, the predicted value u _i of the received signal of the receiving coil D of an arbitrary position and the inclination is determined by the magnetic field intensity function of the above-described (6).
The detector 2, the AC magnetic field transmitted from each transmission coil S _i, the measured value U _i of the signal strength of the received signal as an actual measurement results induced in the receiving coil D ₍₁ ≦ i ≦ 6) Is measured (step S5).

Next, the error minimizing unit 4 compares the measured value U _i of the signal strength as the measurement result with the predicted value u _i obtained by the predicted value calculating unit 3, and compares the signal strength U _i with the predicted value. When it is detected that the difference from u _i is within a preset range, a coincidence signal is output to the position detector 5 (step S4).
Then, the position detection unit 5 detects the position and inclination of the receiving coil D when the predicted value u _i is calculated as the current position and inclination of the receiving coil D, and determines the position and inclination of the receiving coil D as the actual position and inclination. Output.

Therefore, the error minimizing unit 4 has a plurality of positions X (x, y, z) and inclinations (θ ₁ ) so as to minimize an error between the measured value U _i of the signal strength and the predicted value u _i of the signal strength. by putting the data of r _pi and r _ni and phi _i corresponding to the combination of theta ₂₎ to calculate the predicted values u _i, is compared with the actual measured measured value U _i, actually as described above The position and direction in which the receiving coil D is disposed are estimated.
As an evaluation scale of the error, as shown in the following equation (7), a square error total value E obtained by adding all square errors of the measured value Ui and the predicted value ui in each of the transmission coils _Si and the reception coils D is used. Use.

The error minimizing unit 4 calculates the values of the position X (x, y, z) and the gradient (θ ₁ , θ ₂ ) at which the square error total value E is minimum in the above equation (7) as a non-linear minimum self. It calculates | requires by applying a multiplication method (step S4).
That is, the error minimizing unit 4 determines that the square error total value E in the expression (7) satisfies a preset convergence condition (for example, when the square error total value E is equal to or less than a set threshold value, or the square error total value). E until the decrease in the rate of change of E becomes equal to or less than a predetermined value), in steps S1, S2, S3, and S4, the predicted value calculation unit 3 sequentially calculates the new r _pi, r _ni, and φ _i data. using the predicted values u _i in each transmission coil S _i which sums the squared error calculated for each transmission coil Si seeking square error sum E, performing iterative calculations until the following preset threshold. Here, when it is detected that the error minimizing unit 4 is equal to or less than the preset threshold value, it is determined as the minimum value. This threshold value is set in advance by an error between the measured value and the predicted value in an experiment.

  There are various methods for the least square method, but in this embodiment, the Gauss-Newton method or the Gauss-Newton method is considered after considering the balance between the calculation time and convergence stability, the relationship with the function, etc. The basic Levenberg-Marquardt method may be used. Further, other solution methods based on the Gauss-Newton method such as a damping method and a Powell method may be used. Further, instead of the Gauss-Newton method, other nonlinear least squares methods such as the steepest descent method may be used.

Hereinafter, in order to verify the effectiveness of the three-dimensional position detection apparatus in the present embodiment, an application example of the three-dimensional position detection process in the three-dimensional coordinate space of the receiving coil D will be described below.
In the three-dimensional coordinate system shown in FIG. 3A, all combinations of x = {− 30,0,30}, y = {− 30,0,30}, z = {− 30,0,30} The receiving coil is arranged at the position X (the number of positions by the total combination 3 × 3 × 3 = 27 points) from each of the transmitting coils S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ . The signal intensity u _i of the received signal induced by the alternating magnetic field was measured by the detector 2.
The gain G _i in the magnetic field strength function corresponding to each of the transmission coils S _i was corrected using the obtained signal strength.

Next, the detection unit 2 uses the measurement values U of the combinations of the positions x = {− 30,0,30}, y = {− 30,0,30}, and z = {− 30,0,30}. Each _i was measured (step S5).
Then, according to the procedure shown in FIG. 2, the predicted value calculation unit 3 inputs new position and inclination data (step S1), substitutes the input position data into equation (6), and sets r _pi and r _ni is calculated (step S2).
Further, the predicted value calculation unit 3 substitutes the data of the above r _pi and r _ni and the gradient φ _i with respect to the magnetic field peeling into the equation (5) to calculate the predicted value u _i (step S3).
Next, the error minimizing unit 5 performs a calculation that minimizes the square error total value E based on the measured value U _i and the predicted value u _i (step S5).

In the above-described processing, the absolute value error between the actual position of the receiving coil and the predicted position of the receiving coil is 0.2 mm on average, and the position of the receiving coil D is obtained.
In addition, when a magnetic field strength function ignoring the size of the conventional transmission coil is used, the absolute value error is 0.5 mm.
Further, in the method of representing the magnetic field intensity pattern by complementing the magnetic field data for calibration by spline, the total number of calibration data is 375 points, which is about 14 times the 27 points of the present embodiment described above. The amount of data required.
The above-described experiments, the present embodiment can be compared with the conventional method of using a magnetic field intensity function that ignores the size of the transmitting coil S _i, to increase the accuracy of the position detection.
In addition, this embodiment has the same measurement accuracy as the conventional method that performs spline interpolation, but can greatly reduce the number of magnetic field data for calibration.

  A program for realizing the functions of the predicted value calculation unit 3, the error minimization unit 4 and the position detection unit 5 in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is recorded. The processing for detecting the three-dimensional position may be performed by reading the program into a computer system and executing it. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system having a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structural example of the magnetic type three-dimensional position detection apparatus by one Embodiment of this invention. 3 is a flowchart showing an operation of detecting a position of a receiving coil D in a three-dimensional space by the magnetic three-dimensional position detecting device of FIG. 1. It is a conceptual diagram explaining operation | movement of the magnetic type three-dimensional position detection apparatus in this embodiment.

Explanation of symbols

1 ... transmission coil drive section 2 ... detecting section 3 ... predictive value calculating unit 4 ... error minimizing section 5 ... position detector D ... receiving coils _{S 1, S 2, S 3} , S 4, S 5, S 6 ... transmission coil

Claims (6)

A magnetic three-dimensional position detection device that generates alternating magnetic fields of different frequencies from a plurality of transmission coils and further measures a three-dimensional position of the reception coil using a reception signal induced in the reception coil.
For the alternating magnetic field generated from the transmission coil, the magnetic field strength induced in the reception coil is expressed by a magnetic field strength function representing a spatial pattern of the magnetic field strength using a magnetic dipole model considering the size of the transmission coil. A predicted value calculation unit to be obtained;
Minimal error for calculating the three-dimensional position and orientation of the receiving coil so that the error between the signal strength predicted from the magnetic field strength function and the signal strength actually measured by the receiving coil is minimized. And
A magnetic three-dimensional position detection apparatus comprising: a position detection unit that measures the position and orientation of the reception coil based on a result of the error minimizing means.   The magnetic three-dimensional position detection apparatus according to claim 1, wherein the magnetic dipole model represents a magnetic field strength function including position information of both ends of the transmission coil where magnetic charges are arranged. A magnetic three-dimensional position detection method that generates alternating magnetic fields having different frequencies from a plurality of transmission coils, and further measures a three-dimensional position of the reception coil using a reception signal induced in the reception coil.
The predicted value calculation unit induces the AC coil generated from the transmitter coil to the receiver coil by a magnetic field strength function representing a spatial pattern of the magnetic field strength using a magnetic dipole model considering the size of the transmitter coil. Determining the magnetic field strength to be
The three-dimensional position and orientation of the receiving coil so that the error minimizing means minimizes the error between the signal strength predicted from the magnetic field strength function and the signal strength actually measured by the receiving coil. The process of calculating
A magnetic three-dimensional position detection method comprising: a step of measuring a position and an orientation of the reception coil by a position detection unit based on a result of the error minimizing means.   4. The magnetic three-dimensional position detection method according to claim 3, wherein the magnetic field strength function is represented by the magnetic dipole model in consideration of position information of both ends of the transmission coil where magnetic charges are arranged. .   A computer-executable program for causing a computer to execute the magnetic three-dimensional position detection method according to claim 3.   A computer-readable recording medium on which the program according to claim 5 is recorded.

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