JP3236565B2 - Position estimation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position estimating apparatus, and more particularly, to a position estimating apparatus characterized in a position estimating portion of a source coil using a plurality of single-axis coils.

[0002]

2. Description of the Related Art In recent years, endoscopes have been widely used in the medical and industrial fields. This endoscope, especially if the insertion part is flexible, can be inserted into a bent body cavity to diagnose organs deep inside the body cavity without making an incision, and if necessary, insert a treatment tool into the channel. Therapeutic treatment such as resection of polyps and the like.

[0003] In this case, for example, as in the case of examining the lower digestive tract from the anal side, some skill may be required to smoothly insert the insertion portion into a bent body cavity.

[0004] In other words, when the insertion operation is performed, it is necessary to perform an operation such as bending a bending portion provided in the insertion portion in accordance with the bending of the conduit to perform smooth insertion. It is convenient to be able to know the position of the distal end and the like in the body cavity, the current bending state of the insertion portion, and the like.

For this reason, for example, the publication number W of the PCT application
In the prior art of O94 / 04938, an alternating magnetic field having orthogonal vectors in a space is sequentially generated by using three coils having three orthogonal axes fixed at predetermined positions, and the alternating magnetic field is generated in the space. The voltage between both ends of the uniaxial coil, which is induced by the magnetic field generated by the coils of each of the three axes with the uniaxial coil present on the coordinates shown in FIG.
The spatial coordinates of the uniaxial coil were detected based on the measured data.

However, the PCT application publication number WO
In the prior art of 94/04938, if the frequency of the high-frequency signal for generating the magnetic field does not match the frequency of the frequency component extracted by the frequency extracting means due to a change in the ambient temperature or a change over time, Since the value of the frequency component deviates from the value that should be extracted, and the position of the endoscope obtained from this value does not match the actual position, the insertion state may not be detected accurately. Was.

Japanese Patent Application Laid-Open No. 9-28661 discloses a frequency adjusting means for matching the frequency of a high-frequency signal with the frequency of a reference signal. Even in an environment where the frequency of the signal is different from the frequency of the reference signal,
Match, make settings less sensitive,
An endoscope shape detecting device capable of detecting an insertion state of an endoscope has been proposed.

[0008] Publication number WO94 / 04 of the above PCT application
In the prior art of Japanese Patent No. 938, in order to estimate the position of the magnetic generation element from the output values of the plurality of detection elements, a plurality of three-axis coils combining three orthogonal single-core coils are required, which is complicated. Configuration.

[0009] Also, in Japanese Patent Application Laid-Open No. 9-28661, when applying to an endoscope system, in order to estimate the position of the magnetic generating element from the output values of a plurality of detecting elements,
A plurality of three-axis coils, each of which is composed of three orthogonal single-core coils, are required, which again results in a complicated configuration.

Furthermore, in Japanese Patent Application Laid-Open No. 9-28661, it is difficult to make the frequency of a signal sequence and a frequency observed by Fourier transform or the like exactly the same in the analysis of a vector. In this case, it is necessary to reduce the influence of the leak by applying a window function method or the like.

In view of the above, the applicant of the present application has disclosed in Japanese Patent Application No. Hei 9-140603, which was filed earlier, a detecting element (or at least four single-core coils arranged at different positions on the same straight line in the same direction). When estimating a space in which a magnetic generating element (or a detecting element) exists by using a magnetic generating element, a coil position measuring method capable of reducing the number of variables to be estimated has been proposed.

[0012]

However, in Japanese Patent Application No. Hei 9-140603, the above-mentioned problem can be certainly solved. However, by arranging the quadruple sense coils in parallel, each quadruple sense coil is provided. The direction of the error of the circle (error between the center and the radius) estimated by the coil becomes the same, and the error of the estimated three-dimensional position of the source coil increases in a specific direction. There is a problem that the three-dimensional position of the source coil estimated to be far away varies.

The present invention has been made in view of the above circumstances, and includes a plurality of sets of sense coils, each of which has three source coils.
It is an object of the present invention to provide a position estimating device capable of reducing an estimation error when obtaining a dimensional position.

[0014]

A position estimating apparatus according to the present invention comprises: a magnetic field generating source having a single axis transmitting coil for generating a magnetic field; and a magnetic field detecting means for detecting a magnetic field generated by the magnetic field generating source. In a position estimating device that detects the position information of the magnetic field generation source based on the magnetic field detection by the magnetic field detection unit, the magnetic field detection unit includes at least:
A first magnetic field detecting unit in which first, second, third, and fourth single-axis transmitting coils are arranged on a predetermined first axis in the same direction, different from the first axis; The predetermined second axis
On the shaft 5, 6, a second magnetic field detector formed by arranging toward the uniaxial transmitting coil of the seventh and eighth in the same direction, the
A first axis as a center, and the first axis and the magnetic field source;
First calculation for estimating a first circumference whose radius is the distance to
Means , centered on said second axis and in front of said second axis.
Estimating a second circumference whose radius is the distance to the magnetic field source
Second calculating means , the first circumference and the second circumference
Or the point on the first and second circles
Find the point on each circumference where the distance is the minimum, and calculate the intersection,
Or the source of the magnetic field is estimated based on the point where the distance is the minimum.
And means for performing the operation . In addition, the present invention
Is a single-axis transmission core for generating a magnetic field.
A magnetic field source having a magnetic field generated by the magnetic field source.
Magnetic field detecting means for detecting the magnetic field
Information of the magnetic field source based on the magnetic field detection by the means
In the position estimating apparatus for detecting the magnetic field , the magnetic field detecting means
Have at least first, second, and third axes on a predetermined first axis.
And the fourth single-axis transmitting coil is oriented in the same direction
A first magnetic field detection unit, and an axis different from the first axis.
The fifth, sixth, seventh, and eighth units are arranged on a predetermined second axis.
A second magnetic field in which the axis transmitting coils are arranged in the same direction.
A field detection unit, and the second
1 based on the output of the magnetic field detection unit,
Assuming a plane including the first magnetic field detection unit,
Calculated, and the crossing state of the plurality of curves is orthogonal.
Find a near curve, and center on the first axis based on the curve.
And the distance between the first axis and the magnetic field generating source is a radius
First a first calculation means for estimating the circumference, the magnetic to
The output of the first magnetic field detection unit receiving the magnetic field from the field source
Based on the force, and the said magnetic onset Namagen first magnetic field detector
Are calculated assuming a plane including
Among the lines, a curve whose crossing state is nearly orthogonal is obtained, and
Based on the curve, centered on said second axis and said second
A second circumference whose radius is the distance between the axis and the magnetic field generation source is
Second calculating means for estimating , the first circumference and the second
Intersection with the circumference of, or the point on the first and second circumferences
Find the point on each circumference where the distance connecting
A magnetic field is generated based on the point or the point where the distance is minimum.
Means for estimating the source.

[0015]

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 to 39 relate to a first embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an endoscope system, and FIG. 2 is an endoscope of FIG. FIG. 3 is a block diagram showing a functional configuration of the mirror device shape detection device, FIG. 3 is a configuration diagram showing a configuration of the endoscope device shape detection device of FIG. 2, and FIG. 4 is a main part of the endoscope device shape detection device of FIG. FIG. 5 is a timing chart showing the operation of the two-port memory shown in FIG. 4, FIG. 6 is a flowchart showing the operation of the endoscope system shown in FIG. 1, and FIG. FIG. 8 is a flowchart showing the flow of the FFT processing, FIG. 8 is a timing chart showing the parallel processing timing in the operation of the endoscope system in FIG. 6, and FIG. 9 is a first diagram for explaining the principle of the source coil estimated position coordinate calculation processing in FIG. FIG. 10 is a diagram showing the estimated position coordinates of the source coil in FIG. FIG. 11 is a second explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. 6, and FIG. 12 is a third explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. FIG. 13 is a fifth explanatory diagram for explaining the principle of the source coil estimated position coordinate calculation process in FIG. 6, and FIG. 14 is a fourth explanatory diagram for explaining the source coil estimated position coordinate calculation process in FIG. FIG. 15 is a seventh explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. 6, and FIG. 16 is a schematic diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. 8th
FIG. 17 is a ninth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. 6, and FIG. 18 is a tenth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. FIG. 19 is an eleventh explanatory diagram for explaining the principle of the source coil estimated position coordinate calculation process in FIG. 6, and FIG. 20 is a first flowchart showing the flow of the source coil estimated position coordinate calculation process in FIG. Is a second flowchart showing the flow of the source coil estimated position coordinate calculation process in FIG. 6, FIG. 22 is a flowchart showing the flow of the position update control process for the source coil estimated position calculated in FIG. 20 and FIG. 21, and FIG. FIG. 24 is a flowchart showing a flow of the endoscope shape detection image image display processing of FIG. 6, FIG. 24 is a view showing a display example by the normal mode processing of FIG. 23, and FIG.
Is a flowchart showing the flow of the enlargement mode processing in FIG. 23, FIG. 26 is a view showing a display example by the enlargement mode processing in FIG. 25, and FIG. 27 is a 3D model 1 and 3D in the endoscope shape detection image image display processing in FIG. FIG. 28 is a first explanatory diagram illustrating an image model of model 2, and FIG.
FIG. 29 is a flowchart showing a display process of the image models of the D model 1 and the 3D model 2. FIG. 29 is a second description for describing the image models of the 3D model 1 and the 3D model 2 in the endoscope shape detection image image display process of FIG. FIG. 30 is a first flowchart showing the flow of the color tone correction process of FIG. 29, FIG. 31 is a first explanatory diagram for explaining the operation of the color tone correction process of FIG. 30, and FIG. FIG. 33 is a second flowchart showing the flow, and FIG.
FIG. 34 is a second explanatory diagram for explaining the operation of the color tone correction processing of FIG.
Is a flowchart showing a display process of an image model of a 2D model in the endoscope shape detection image image display process of FIG. 6, and FIG. 35 is a diagram showing a display example of an endoscope shape detection image image displayed by the process of FIG. FIG. 36 shows FIG.
37 is a flowchart showing a display process of an image model of a 12-point model in the endoscope shape detection image image display process of FIG. 37. FIG. 37 is a diagram showing a display example of an endoscope shape detection image image displayed in the process of FIG. 38 is a flowchart showing a display process of an image model of a straight line model in the endoscope shape detection image image display process of FIG. 6, and FIG. 39 shows a display example of an endoscope shape detection image image displayed by the process of FIG. FIG.

(Configuration) As shown in FIG. 1, an endoscope system 1 according to the present embodiment is an endoscope apparatus 2 for performing an endoscopic inspection.
And an endoscope device shape detection device 3 used for assisting an endoscopy. The endoscope shape detection device 3 inserts an electronic endoscope 6 into a body cavity of a patient 5 lying on a bed 4. Part 7
Is used as an insertion assisting means when performing endoscopy.

The electronic endoscope 6 has an operating section 8 provided with a bending operation knob at the rear end of an elongated insertion section 7 having flexibility, from which a universal cord 9 is extended. It is connected to a video imaging system (or video processor) 10.

The electronic endoscope 6 has a light guide inserted therein, transmits illumination light from a light source unit in the video processor 10, and emits the transmitted illumination light from an illumination window provided at the tip of the insertion unit 7. Illuminate the patient etc. The illuminated subject such as a diseased part forms an image on an imaging device arranged at an image forming position by an objective lens attached to an observation window provided adjacent to the illumination window, and the imaging device performs photoelectric conversion.

The photoelectrically converted signal is supplied to the video processor 1
The video signal is processed by a video signal processing unit in 0 to generate a standard video signal, which is displayed on an image observation monitor 11 connected to a video processor 10.

The electronic endoscope 6 has a forceps channel 12
Is provided, and an insertion port 12a of the forceps channel 12 is provided.
, A source coil 14i is installed in the insertion portion 7 by inserting a probe 15 having, for example, 16 magnetism generating elements (or source coils) 14a, 14b,. Is done.

The source cable 16 extending from the rear end of the probe 15 has a connector at the rear end detachably connected to the apparatus main body 21 of the endoscope shape detecting apparatus 3. Then, by applying a high-frequency signal (drive signal) to the source coil 14i, which is a magnetic generation unit, via the source cable 16 as a high-frequency signal transmission unit from the apparatus main body 21 side, the source coil 14i transmits an electromagnetic wave accompanied by a magnetic field to the surroundings. Radiate.

The bed 4 on which the patient 5 lies is a magnetic sensing element (or sense coil) having a common center and having at least four single-core coils 22k for detecting a magnetic field on the same straight line in the same direction. For example, four sense coils 22a, 22b, 22c, and 22d (hereinafter, represented by 22j) are replaced with a sense coil 22a and a sense coil 22.
b is set in parallel, and the sense coil 22c and the sense coil 22d are installed in a well-shaped position orthogonal to the sense coil 22a and the sense coil 22b. In this case, the single-core coil 22k is 16 in total.

The sense coil 22j is connected from the connector of the bed 4 to the apparatus main body 21 via a sense cable 23 as a detection signal transmitting means. This device body 2
1 is provided with an operation panel 24 or a keyboard for a user to operate the apparatus. Further, a monitor 25 is connected to the apparatus main body 21 as display means for displaying the detected endoscope shape.

Further, a detailed configuration of the endoscope shape detecting device 3 will be described. As shown in FIG. 2, the endoscope shape detection device 3 includes a drive block 26 for activating the source coil 14i, a detection block 27 for detecting a signal received by the sense coil 22j, and a signal detected by the detection block 27. And a host processor 28 for signal processing.

As shown in FIG. 3, the probe 15 installed in the insertion section 7 of the electronic endoscope 6 has 16 source coils 14i for generating a magnetic field at predetermined intervals as described above. These source coils 14i
Is a source coil drive circuit 31 that generates 16 different high-frequency drive signals constituting the drive block 26
It is connected to the.

The source coil drive circuit 31 drives each of the source coils 14i with sine wave drive signal currents having different frequencies, and the respective drive frequencies are stored in a drive frequency setting data (not shown) inside the source coil drive circuit 31. The driving frequency setting data (also referred to as driving frequency data) stored in the driving frequency setting data storage means. The drive frequency data is transferred to a drive frequency data in a source coil drive circuit unit 31 via a PIO (parallel input / output circuit) 33 by a CPU (central processing unit) 32 which performs an endoscope shape calculation process and the like in a host processor 28. It is stored in storage means (not shown).

On the other hand, the 16 single-core coils 22 k constituting the four sense coils 22 j are connected to the sense coil signal amplifier circuit 34 constituting the detection block 27.

As shown in FIG. 4, in the sense coil signal amplifying circuit section 34, a single-core coil 22k is connected to an amplifying circuit 35k provided for one system for each single-core coil 22k. After a small signal is amplified by the amplifier circuit 35k and has a band through which a plurality of frequencies generated by the source coil group pass through the filter circuit 36k, unnecessary components are removed, and the signal is output to the output buffer 37k. ) At 38k, it is converted into a digital signal that can be read by the host processor 28.

The detection block 27 comprises a sense coil signal amplifier circuit 34 and an ADC 38k. The sense coil signal amplifier circuit 34 comprises an amplifier circuit 35k, a filter circuit 36k and an output buffer 37k.

Returning to FIG. 3, the outputs of the 16 systems of the sense coil signal amplifying circuit 34 are provided by 16 ADCs 38.
k and is converted into digital data of a predetermined sampling cycle by a clock supplied from the control signal generation circuit unit 40. This digital data is transmitted to the local data bus 4 by a control signal from the control signal generation circuit 27.
The data is written to the two-port memory 42 via 1.

The two-port memory 42, as shown in FIG. 4, functionally comprises a local controller 42a, a first RAM 42b, a second RAM 42c, and a bus switch 42d. Accordingly, the ADC 38k starts A / D conversion in response to an A / D conversion start signal from the local controller 42a, and the bus switch 42d alternately reads the first RAMs 42b and 42c while switching between the RAMs 42b and 42c in response to a switching signal from the local controller 42a. It is used as a memory and a write memory, and always receives data after power is turned on by a write signal.

Returning to FIG. 3 again, the CPU 32 transmits the digital data written to the two-port memory 42 by the control signal from the control signal generation circuit 27 to the local data bus 43, the PCI controller 44, and the PCI bus 45.
(See FIG. 4) via an internal bus 46,
Using the main memory 47, frequency extraction processing (Fourier transform: FFT) is performed on digital data as described later.
Is performed to separate and extract magnetic field detection information of a frequency component corresponding to the driving frequency of each source coil 14i. Each source provided in the insertion unit 7 of the electronic endoscope 6 is extracted from each digital data of the separated magnetic field detection information. The spatial position coordinates of the coil 14i are calculated.

The insertion state of the insertion section 7 of the electronic endoscope 6 is estimated from the calculated position coordinate data, display data for forming an endoscope shape image is generated, and output to the video RAM 48. The data written in the video RAM 48 is read out by the video signal generation circuit 49, converted into an analog video signal, and output to the monitor 25. When the analog video signal is input, the monitor 25 displays the insertion shape of the insertion section 7 of the electronic endoscope 6 on the display screen.

In the CPU 32, each source coil 14
The magnetic field detection information corresponding to i, that is, the electromotive force (the amplitude value of the sine wave signal) and the phase information generated in the four single-core coils 22k of each sense coil 22j are calculated. Note that the phase information indicates the polarity ± of the electromotive force.

(Operation) A method for estimating the three-dimensional position of a source coil from two sense coils orthogonal to two orthogonal sense coils and a method for estimating the space in which the source coil is present from the output of the sense coil is disclosed in Japanese Patent Application No. 2006-110,086. 9-1406
This is the same as the embodiment of No. 03.

In the present embodiment, the 4
A description will be given of a method of extracting a plurality of sense coils that accurately estimate the space where the source coil exists from among the sense coils, and estimating the three-dimensional position of the source coil from the extracted sense coils.

In the endoscope system 1 of this embodiment, when the power is turned on, as shown in FIG. 6, each system parameter is initialized based on the parameter file in step S1, and the hardware initialization is performed in step S2. Perform the conversion.

After the power is turned on, the 2-port memory 42 stores F
The data for the number of FFT points for performing the FT processing is constantly updated (see FIG. 5), and in step S3, the CP
U32 takes in the data for the number of FFT points. Then, in step S4, the data is corrected by a process using the window function method, and in step S5, an FFT process described later is performed. After the FFT processing, the frequency components for the driving frequency are extracted in step S6, the amplitude value and the phase difference are calculated in step S7, and the amplitude value and the phase difference calculated in step S8 are corrected.

Then, in step S9, the eight ADCs
Signal from 38k (hereinafter also referred to as channel: CH)
It is determined whether or not all the detections have been completed. If the detection has not been completed, the process returns to step S3. If the detection has been completed, the amplitude values for all the channels are corrected in step S10 according to the sense coil characteristics. The estimated position coordinate of the source coil 14i is calculated from the amplitude value and the phase difference by the method described later.

Thereafter, in step S12, it is determined whether or not the system end switch of the endoscope system 1 is turned on. If not, an endoscope shape detection image image display process described later is performed in step S13, and the process returns to step S3. Repeat the process. When the system end SW of the endoscope system 1 is turned on in step S12, the system ends after saving each system parameter in a parameter file in step S14.

In the FFT processing in step S5, as shown in FIG. 7, the CPU 32 determines in step S21 whether or not all the channels are in a signal state (a state in which data for the number of FFT points are complete). Step S2
If it is not in the signal state, the process waits until it becomes the signal state in step S23, and proceeds to step S22.

In step S22, C for performing FFT processing
The state of the H bit (if the bit is 0, the data for the current process, if the bit is 1, the processed data) is determined, and if the bit is 0, FFT is performed in step S24.
After the FFT, the state of the bit is set to 1 in step S25. If the bit is 1 in step S22, the process returns to step S21, and the process is repeated for all the second and subsequent channels to perform the FFT process on all the channels.

In step S26 after step S25,
It is determined whether the bit status of all CHs is 1 and all C bits are determined.
If the bit state of H is not 1, the step S21 is performed to perform the FFT processing on the CH whose bit state is not 1.
Return to In step S26, the bit status of all CHs is 1
When all the CHs are set to the non-signal state in step S27, the process waits. When the data for the number of FFT points are completed, the signal state is set in step S28.
Return to 21.

In the processing of FIG. 6, in order to perform high-speed processing, as shown in FIG. 8, each processing unit is processed in parallel. In particular, the FFT, which has a long processing time and is an iterative operation, is configured to process the same processing unit almost simultaneously. This parallel processing supports CP
The speed is increased by effectively using the idle time of U32.

As described above, the CPU 32 implements the frequency extraction processing based on the Fourier transform. Here, the frequency f of the sine wave driving each source coil 14i
A phenomenon called leakage caused by the relationship between _i and the censoring width of digital data becomes a problem.

If the cut-off width of digital data to be sampled (that is, the length corresponding to the length of the signal train) is an integral multiple of the period of all drive frequencies f _i ,
It is possible to accurately obtain the amplitude and phase information (so-called amplitude spectrum and phase spectrum) of the sine wave of each frequency. However, if the censoring width is at least one
One of leakage occur unless an integral multiple with respect to the period of the driving frequency f _i, is reflected as an error in the amplitude and phase information is calculated. In order to prevent this, generally Hamming
A window function method using a window or the like is used (Reference: THE
FAST FOURIER TRANSFORM E.
ORAN BRIGHAM Sec. 6).

However, the window function method only reduces errors due to leakage. In addition, it is necessary to use a value that minimizes the influence of leakage as the drive frequency, which may be a constraint.

The frequency extraction processing in step S6 in FIG. 6 that enables the influence of the leakage to be positively corrected by a simple matrix operation to obtain more accurate amplitude and phase information will be described.

For the sake of simplicity, it is assumed that normalization of the result of Fourier transform and compensation of the window function (rectangular window or the like) by the coefficient times have already been performed.

[0052] Fourier transform of the signal sequence composed of sine waves of a certain frequency f _k (in this case a complex discrete Fourier transform) F _k is

(Equation 1) It is represented by Here, N is the length of the sampled discrete signal sequence, and j is the imaginary unit. F _k is real number times Re ｛F
_k } and an imaginary multiple Im {F _k }.

On the other hand, the condition that the cutoff width of the digital data is an integral multiple of the period of the driving frequency f _i is determined by the frequency fs _i observed by the discrete Fourier transform.
And the driving frequency f _i corresponds with the equal. If this condition is not satisfied, an error occurs between the observation frequency fs _i and the drive frequency f _i (that is, the frequency f _i cannot be observed). If the if all the observation frequency fs _i and relationships are equal driving frequency f _i, truncation width leakage does not occur because it is an integral multiple with respect to the period of all the driving frequency f _i.

Here, a method for deriving the Fourier transform F _i of the driving frequency f _i , which should be originally obtained, from the Fourier transform Fs _i obtained at the observation frequency fs _i will be described.

The signal sequence based on the sampled digital data has a driving frequency f _i (i = 1, 2,...,
M), the relationship between each Fourier transform of the observation frequency fs _i and the driving frequency f _i is as follows:

(Equation 2) It can be expressed as. In the formula (2), A is Re
{F ₁ }, Im ｛F ₁ } or Re ｛F _M ｝, Im ｛F _M
｝ Is a 2M × 2M matrix composed of a coefficient sequence defining the amount of leakage during｝.

Here, equation (2) is renewed.

## EQU3 ## It is assumed that Y = A.X (3). In equation (3), the matrices X and Y are the driving frequency f _i and the observation frequency fs _i (i = 1, 2, 2), respectively.
, M) is a 2M × 1 matrix composed of a real number multiple of the Fourier transform and an imaginary part. In matrix X,

X = X ₁ = [1,0,0,0,..., 0,0,0] ^t (4) (t represents transposition) because the signal train is at the drive frequency f
_{1. This} is a case where only a sine wave (ie, a cosine wave) having an amplitude of ₁ and a phase shift of π / 2 is used. Also,

X = X ₂ = [0,1,0,0,..., 0,0,0] ^t (5) is a sine wave having a drive frequency f1 and a phase of 0 in the signal train. This is the case where the configuration is made up of only the above.

Similarly

X = X ₃ = [0,0,1,0, ..., 0,0,0] ^t , X = X ₄ = [0,0,0,1, ..., 0,0,0] ^t ,:: X = _X2M-1 = [0,0,0,0, ..., 0,1,0] ^t , X = _X2M = [0,0,0,0, ..., 0,0, 1] ^t ... (6) are the driving frequencies f _i (here, i
= 2, 3,..., M), which is generated by giving a sine wave of amplitude 1 having a phase shift of π / 2 or 0.

On the other hand, the matrix Y obtained when the matrices X ₁ , X _{2 ,.
1} , Y ₂ ,..., Y _2M . The matrices Y ₁ to Y _2M are leaked when digital data based on a signal sequence that should be obtained as matrices X ₁ to X _2M is given (in this case, a value other than 0 is added to a term which becomes 0 in the matrix X). Resulting in an observation with a value that should be 1 becomes another value, etc.). Since these matrices Y = Y ₁ , Y ₂ ,..., Y _2M are nothing but terms constituting each column of the matrix A,

It can be seen that A = [Y ₁ , Y ₂ , Y ₃ ,..., Y _2M ] (7)

[0059] In summary, the Fourier transform F _i (originally the frequency extraction information to be used in calculating the amplitude and phase information) matrix X consisting of the drive frequency f _i is

X = A ^-1 · Y (8) The Fourier transform Fs _i of the observation frequency fs _{i represented} as (8)
Obtained by the inverse matrix multiplication of A ^-1 of the matrix A for the matrix Y consisting of the matrix A matrix as described above X = X _1,
X _2, X _3, ..., matrices obtained respectively when given a signal sequence to the _{X 2M Y = Y 1, Y} 2, Y 3, ..., can be constructed from Y _2M.

Therefore, the inverse matrix A ^-1 of the matrix A obtained in advance is converted into the matrix Y obtained from the Fourier transform of the signal sequence.
, The frequency information can be extracted more accurately, and a highly accurate position estimation for the source coil 14i can be achieved.

Further, a matrix Q having a size of 2M × N for simultaneously executing the Fourier transform and the multiplication of the matrix A ⁻¹ is prepared, and the matrix X is obtained by directly multiplying the digital data having a length of N × 1. Is also possible.

As a result, the accuracy of the source coil position estimation in the endoscope shape detecting device is improved, and the degree of freedom in selecting the driving frequency is improved.

Next, the source coil estimated position coordinate calculating process in step S11 of FIG. 6 will be described. First, a method of calculating source coil estimated position coordinates will be described, and then specific processing contents will be described.

As shown in FIG. 9, in the case of a thin circular coil having a very small radius, as described in Japanese Patent Application Laid-Open No. 9-84745, when a current is applied to the circular coil, a three-dimensional coil is formed similarly to a magnetic dipole. The magnetic potential of a point P in space can be expressed by the following equation.

[0065]

(Equation 9) μ: magnetic permeability N ₁ : number of turns of a circular coil a: radius of a circular coil I: current flowing in a circular coil Accordingly, magnetic fields (H _Px , H _Py , H _Pz ) at the point P in the same direction as the X, Y, and Z axes. Is

(Equation 10) Is required. In three-dimensional space as shown in FIG. 10 (hereinafter the world coordinate system X _W -Y _W -Z _W), the position of the single core coil (hereinafter source coil) for generating a magnetic field _{(x gW, y gW, z} gW) And an arbitrary position on the three-dimensional space is defined as a point P (x _PW , y _PW , z _PW ).

[0066] When coordinate system relative to the source coil and the local coordinate system X _L -Y _L -Z _L, of the point P in the local coordinate system coordinates _{(x Pl, y Pl, z} Pl) is

[Equation 11] P _l : vector from the origin O to the point P in the local coordinate system P _W : vector from the origin O to the point P in the world coordinate system G _W : vector from the position of the source coil in the world coordinate system R: rotation matrix be able to.

Here, R is a rotation matrix, and the rotation matrix R of the polar coordinate system shown in FIG.

(Equation 12) Becomes α is the amount of rotation around the Z _W-axis, beta represents the rotation amount around the X _W axis.

In the local coordinate system based on the source coil, the magnetic field H ₁ (H _Pxl , H _Pyl ,
H _Pzl ) is from equation (10)

(Equation 13) Becomes

Therefore, X at point P in the world coordinate system
The magnetic field H _W (H _PxW , H _P) in the same direction as the _W , Y _W , and Z _W axes
_PyW , H _PzW )

[Equation 14] Becomes

As shown in FIG. 12, a source coil is placed at an appropriate position (X _g , Y _g , Z _g ) in a three-dimensional space, and a magnetic field generated by the source coil is detected as an electromotive force.
Position single core coil (hereinafter sense coils) oriented in the same direction and the Y-axis on the axis _{(X d, Y d, Z} d) a magnetic field H _y position of the sense coil when placed in the equation (14)

(Equation 15) Becomes

Further, the electromotive force V generated in the sense coil
_y is expressed by the following equation by partially differentiating the magnetic field _Hy with time t.

[0072]

(Equation 16) N ₂ : number of turns of the sense coil ωI _max cos (ωt + φ): value obtained by differentiating current I _max sin (ωt + φ) flowing through the source coil with respect to time t As shown in FIG. 13, a circle is drawn around the Y axis, When the source coil is moved along the circumference, a constant electromotive force is always generated in the sense coil. However, the direction of the sense coil viewed from the Y axis is always the same.

At this time, by arranging a plurality of sense coils on the Y axis, it is possible to estimate a space where the source coil exists, that is, a circle centered on the Y axis.

As shown in FIG. 14, four sense coils are placed on the Y axis, and the coordinate system of a plane γ constituted by the Y axis and the position of the source coil is X′-Y ′. The generated electromotive force Vyi is

[Equation 17] Becomes Here, g _x and g _y are terms expressed by the plane γ and the direction of the source coil, and x _di and y _di are expressed in the coordinate system X′−
The position of the sense coil at Y ′, x _g ′ and y _g ′ represent the position of the source coil.

Equation (17) shows that four unknowns (g _x , g _y ,
x _g ′, y _g ′), four equations can be obtained by arranging at least four sense coils in the same direction on the Y axis, and by solving the equations, the coordinate system X′−Y ′ can be obtained. The position of the source coil at is obtained.

More specifically, as shown in FIG. 15, a source coil for generating a magnetic field in a three-dimensional
Place four sense coils on the axis. The plane γ formed by the source coil and the four sense coils is defined as X′−Y ′
And the position of the source coil at that time is (x _g , y
_g ), the position of each sense coil is (x _d0 , y _d0 ), (x
_d1 , _yd1 ), ( _xd2 , _yd2 ), ( _xd3 , _yd3 ).

The electromotive forces V _y0 , V _y1 , V _y2 , and V _y3 generated in each of the sense coils C _s0 , C _s1 , C _s2 , C _s3 are given by the following equation (17).
More like this:

[0078]

(Equation 18)

[Equation 19]

(Equation 20)

(Equation 21) Here, k _si (i = 0, 1, 2, 3) is a constant determined by the current amount of the source coil and the number of turns of each sense coil.

Expressions (19) and (20) can be expressed by a matrix.

(Equation 22) And the term represented by the positions of the sense coil and the source coil is represented by matrix A.

[0080]

(Equation 23) When the inverse matrix A ^-1 of the matrix A is obtained from Cramer's equation,

(Equation 24) And g _x and g _y can be calculated as follows.

[0081]

(Equation 25) The inverse matrix A ^-1 is calculated, and g _x and g _y are calculated according to equations (18) and (2).
Substituting into 1)

(Equation 26)

[Equation 27] Becomes However,

[Equation 28] It is.

Equations (26) and (27) are nonlinear equations with x _g and y _g as unknowns. By applying the Newton method to these two nonlinear equations, x _g and y _g are obtained.

The electromotive force actually generated in the sense coil is V
_y0 ', V _y3', equation (26), when the estimated value V _y0, V _y3 (27), each of the difference values

F ₁ (X _g , Y _g ) = V _y0 −V _y0 ′ (29)

F ₂ (X _g , Y _g ) = V _y3 −V _y3 ′ (30) In equations (29) and (30), the electromotive forces V _y0 ′ and V _y3 ′ generated in the sense coil are accurately measured, and x _g and y _{g of} the estimated values V _y0 and V _y3 are completely equal to the position of the source coil. , The value on the right side of Expressions (29) and (30) becomes 0.

Then, in order to estimate the position of the source coil, x _g and y _g satisfying f ₁ = 0 and f ₂ = 0 are obtained.

When the f ₁ and f ₂ are partially differentiated with respect to x _g and y _g ,
Jacobi matrix J is

(Equation 31) Becomes

The inverse matrix J ^-1 of the Jacobian matrix J is obtained from the Cramer's equation, and is referred to as a matrix C.

[0087]

(Equation 32) The Newton method is an iterative solution of a nonlinear equation f (Χ) = 0 defined by Χ ^{(k + 1)} = Χ ^(k) −ΔΧ ^(k) , and the correction amount ΔΧ ^(k) is expressed by Χ of f (Χ). = Χ ^(k) is determined based on linear approximation.

[0088] ^{ΔΧ (k) = J -1 (} Χ (k)) f (Χ (k)) Now, x _g, the appropriate initial value of y _g and x _g0, y _g0 x _g, the y _g The approximate values x _g1 and y _g1 are

X _g1 = x _g0 − {c ₀₀ f ₁ (x _g0 , y _g0 ) + c ₀₁ f ₂ (x _g0 , y _g0 )} (33)

Y _g1 = y _g0 − {c ₁₀ f ₁ (x _g0 , y _g0 ) + c ₁₁ f ₂ (x _g0 , y _g0 )} (34)

X _g1 and y _g1 are substituted into equations (29) and (30). If the values of f ₁ and f ₂ do not become 0, the equation (33)
By substituting x _g1 and y _g1 for x _g0 and y _g0 in (34), x _g2 and y _g2
And calculate f ₁ and f ₂ again. By repeating this operation, f ₁ and f ₂ approach 0, and x _g and y _g are obtained.

Although the nonlinear equation is solved by the Newton method, a method such as the least square method may be used.

From the output values of the sense coils in which at least four single-core coils are arranged in the same direction on the same straight line, the position of the source coil on the plane formed by the sense coil and the source coil can be estimated. That is, the space (circle) where the source coil exists in the three-dimensional space is estimated.

Therefore, a sense coil in which at least four single-core coils are arranged on the same straight line in the same direction in a space,
By arranging at least two, three of the source coils
The dimensional position can be estimated (determined as the intersection of two circles in space).

The sense coil 22k is composed of four single-core coils. Next, the output value of the single-core coil that generates the maximum output value among the four single-core coils of the sense coil is extracted, and Largest maximum output value 2
Select one sense coil.

The three-dimensional position of the source coil is estimated according to the arrangement condition of the two selected sense coils, that is, orthogonal or parallel.

In the present embodiment, the intersection of two circles in space or the point on each circle at which the distance connecting the points on two circles is the shortest (the intersection between the two circles due to noise or the like is determined). In some cases).

First, the case where two selected sense coils are arranged orthogonally will be described. As shown in FIG. 16, when the source coil is placed at an appropriate position and the sense coils are placed on the X axis and the Y axis, circles C ₁ and C ₂ where the source coils are located are obtained from the output values of each sense coil. .

C ₁ exists on the plane x = a ₁ and the center (a
₁ , 0, 0), a circle having a radius r _{1, and} a circle having a center (0, b ₂ , 0) and a radius r ₂ where C ₂ exists on a plane y = b ₂ ,

[Number 35] _{C 1: (x-a 1} ) 2 + y 2 + z 2 = r 1 2 ... (35)

[Number 36] C ^_2: x ₂ + a ^{_{(y-b 2) 2 +}} z 2 = r 2 2 ... (36).

On the other hand, as shown in FIG.
The coordinates of the point Q when vertically lowered from (x ₁ , y ₁ , z ₁ ) to the plane y = b ₂ are (x ₁ , b ₂ , z ₁ ).

A straight line m on the plane y = b ₂ passing through the point Q and the center (0, b ₂ , 0) of the circle C ₂ is obtained by using the real variable t.

X = x ₁ + t x ₁ y = b ₂ z = z ₁ + tz ₁ (37) Substituting equation (35) into equation (36) for the circle C ₂ gives

[Number 38] ^{_{(x 1 + tx 1) 2}} + (z 1 + tz 1) 2 = r 2 2 ... (38) next, t is as follows.

[0100]

[Equation 39] Although there are two intersections between the straight line m and the circle C2, here, t
Consider the case of> 0. Substituting equation (39) into equation (37)

(Equation 40) Becomes Equation (40) represents the point P 'of the closest on the circle C ₂ at point P, as shown in FIG. 17.

At this time, as shown in FIG. 18, the point P (x
₁ , y ₁ , z ₁ ) are on the circle C ₁

X ₁ = a ₁ y ₁ = r ₁ cos θ z ₁ = r ₁ sin θ (41) which is substituted into equation (40).

(Equation 42) Becomes

The distance between the point on the circle C ₁ and the point on the circle C ₂ is 2
The power D is

[Equation 43] Differentiating Equation (43) with respect to θ gives

[Equation 44] Becomes

The condition for making equation (44) 0 is sin θ = 0 (two circles have no intersection, and r ₁ <a ₁ and r ₁ <b ₂ or r ₁ <b ₂ or r ₂ <a ₁ ) Or

[Equation 45] It is.

Therefore, θ satisfying the expression (45) is

[Equation 46] The coordinates of points on the circumference of each of the circles C ₁ and C ₂ can be obtained from Expression (46) and Expressions (40) and (41).

Assuming that a point on the circle C ₁ is (x _c1 , y _c1 , z _c1 ) and a point on the circle C ₂ is (x _c2 , y _c2 , z _c2 ), the position (x _g , y _g ) of the source coil , Z _g ) are determined, for example, as the average value of each coordinate value.

[0106]

[Equation 47] Therefore, the single-core coil is placed on the same straight line in the same direction.
By using two sense coils arranged side by side, the position of the source coil in space can be estimated.

Next, the case where the two selected sense coils are arranged in parallel will be described. As shown in FIG. 19, the position of the source coil is estimated by arranging the sense coils in parallel. Now, the circle C ₁ obtained by the sense coil is

Equation 48] _{x = a 1 y = b 1} + r 1 cosθ z = r 1 sinθ ... (48) Further, a circle C ₂

X = a ₂ y = b ₂ + r ₂ cos φ z = r ₂ sin φ (49) A point on _{C 1 P 1 (x 1,} y 1, z 1), C 2
If the upper point is P ₂ (x ₂ , y ₂ , z ₂ ), the circle C ₁ ,
Condition when a point on the C ₂ intersect or be closest is

Y1 = y2 and z1 = z2 (50)

Expressions (48) and (49) are substituted into conditional expression (50).

[Formula 51] b ₁ + r ₁ cos θ = b ₂ + r ₂ cos θ (51)

Equation 52] _{r 1 sinθ = r 2 sinφ ...} (52) Equation (52) r ₁ ² When squaring both sides of ^{(1-cos 2 θ) =} r 2 2 (1-cos 2 φ) , and the formula ( 51) is substituted and arranged.

[0109]

(Equation 53) Equations (48) and (53), Equations (49) and (52),
From (53), the intersection (a ₁ = a ₂ ) of the circles C ₁ and C ₂ or the two closest points can be obtained.

When the two closest points on the circles C ₁ and C ₂ are obtained, as shown in the case where they are arranged orthogonally,
One coordinate value is estimated by averaging the components in the X-axis direction (one component in the Y- and Z-axis directions is determined by Expression (53)).

Next, the CPU 32 based on the method described above is used.
The following describes a specific source coil estimated position coordinate calculation process in.

As shown in FIG. 1, four single-core coils are arranged on the bed 4 and four sense coils 22j are arranged on the same straight line in the same direction. Further, the probe 15 of the source coil 14i having 16 single-core coils connected thereto is inserted from the forceps channel 12 of the electronic endoscope 6.

In the endoscope shape detecting device 3, the maximum amplitude value and the phase of the voltage generated in the sense coil 22j corresponding to each source coil 14i are obtained, and ± polarity of the maximum amplitude value of the voltage is determined from the phase value. , A voltage value having a polarity is set as a voltage value of the sense coil 22j.

That is, as shown in FIG. 20, the CPU 32 initializes the order of the source coil 14i and the sense coil 22j which are processed first in steps S31 and S32. That is, in step S31, i is set to 0, and in step S32, j is set to 0.

First, the 0th source coil and the 0th sense coil are selected. In step S33, the voltage values V ₀₀ , V ₀₁ , V ₀₁ generated in the four single-core coils of the 0th sense coil are selected. ₀₂ and V ₀₃ are taken in. And
In step S34, the 4 captured in step S33
The maximum voltage value V _max [j] of the two voltage values is detected.

A step S35 detects whether or not the detection of the maximum voltage value of all the sense coils has been completed. If not, the flow advances to a step S36 to increment j.
It returns to step S33.

When step S35 ends, step S
Proceeding to 37, the maximum voltage value of the absolute value of each sense coil is compared, and two large sense coils are extracted.

In step S38, the two-dimensional positions (x ′ _g00 , y ′ _g00 ) of the source coils on the respective planes formed by the 0th source coil with respect to the two sense coils extracted in step S37. ),
(X ′ _g01 , y ′ _g01 ) is obtained.

A step S39 decides whether or not the arrangement of the two sense coils extracted in the step S37 is orthogonal. If the arrangement is orthogonal, the step S40 in FIG.
If not, the process proceeds to step S41 in FIG.

As shown in FIG. 21, in step S40, a circle in which the source coils exist in a relationship where the two sense coils are orthogonal to each other is calculated. In step S41, the source coil in a relationship where the two sense coils are parallel is calculated. Is calculated.

In step S42, from the two circles calculated based on the arrangement conditions of the two sense coils, a point on the circumference at which each point on the circumference comes closest is calculated.

Then, in step S43, step S4
From the two points calculated in step 2, the position (x _g0 , y _g0 , z _g0 ) of the 0th source coil in the three-dimensional space is obtained, and in step S44, the three-dimensional positions (x _gi , y) of all the source coils are obtained.
_gi , z _gi ) is determined, and if the three-dimensional positions (x _gi , y _gi , z _gi ) of all the source coils have not been determined, i is incremented in step S45 of FIG. Returning to step S32, the process is repeated until the three-dimensional positions ( _xgi , _ygi , _zgi ) of all the source coils are obtained, and the process ends.

Therefore, by using four sense coils in which four single-core coils are arranged on the same straight line in the same direction, the position of the source coil in space can be estimated.

In this embodiment, the necessary sense coils are extracted from the magnitude of the absolute value of the maximum voltage of each sense coil. However, the source coil on the plane formed by each of the four sense coils and the source coil is extracted. The three-dimensional position of the source coil may be estimated by estimating the position of the coil and detecting two sense coils in which the distance between the source coil and the sense coil is short (the radius of the circle is small).

Although the position of the source coil in the space estimated in this way is constantly updated, the position update control processing shown in FIG. 22 is performed on the position of the source coil. That is, as shown in FIG. 22, for example, the coordinates of the position (three-dimensional position) of the 0th source coil in space are (x ₀ ,
y _0, z ₀₎ and the time, the three-dimensional estimated coordinates in step _{S51 (x 0, y 0,} z 0) to enter, the three-dimensional estimated coordinates in step _{S52 (x 0, y 0,} z 0) Are the first three obtained by the first source coil estimated position coordinate calculation process.
It is determined whether the coordinates are the estimated three-dimensional coordinates. If the coordinates are not the first estimated three-dimensional coordinates, the process proceeds to step S53. If the coordinates are the first estimated three-dimensional coordinates, the process proceeds to step S54.

In the case of the first three-dimensional estimated coordinates, step S
At step 54, the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) are stored as the previous three-dimensional estimated coordinates (x _B , y _B , z _B ), and step S
At 55, the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) are output as the source coil estimated position coordinate calculation processing, and the processing is terminated.

Next, instead of the first three-dimensional estimated coordinates,
The three-dimensional estimated coordinates (x ₀ , y ₀ ,
z ₀ ) will be described. Also in this case, step S51
Input the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ), and in step S52, input the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ).
Is determined to be the first three-dimensional estimated coordinate obtained by the first source coil estimated position coordinate calculation process. However, since it is not the first three-dimensional estimated coordinate, the process proceeds to step S53.
The absolute value of the difference between the current three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) and the previous three-dimensional estimated coordinates (x _B , y _B , z _B ) is a variation in predetermined x, y, z coordinates. limit x _s, y _s, it is determined whether or not exceed z _s, in a case when it does not exceed the first 3
Similarly to the three-dimensional estimated coordinates, in step S54, the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) are changed to the previous three-dimensional estimated coordinates (x _B ,
y _B , z _B ), and the three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) are output as the source coil estimated position coordinate calculation processing in step S55, and the processing ends.

In step S53, the current three-dimensional estimated coordinates (x ₀ , y ₀ , z ₀ ) and the previous three-dimensional estimated coordinates (x _B , y
_B, the absolute value of the difference between z _B) are given x, y, variation limiting value x _s z-coordinate, y _s, it is determined to be above a z _s, the flow advances to step S56, the previous 3-dimensional estimation the coordinates (x _B, y _B,
z _B ) is set as the output of the source coil estimated position coordinate calculation process, and the process ends.

As described above, with respect to the position of the source coil,
Given x, y, variation limiting value x _s z-coordinate, y _s, the location updating control processing by z _s is performed.

In FIG. 22, the 0th source coil has been described as an example, but this process is performed on all the source coils.

Next, the endoscope shape detection image image display processing in step S13 in FIG. 6 will be described.

The endoscope shape detection image image display processing is as follows.
As shown in FIG. 23, the endoscope shape model data is constructed based on the coordinates of the position (three-dimensional position) in the space of the source coil output from the source coil estimated position coordinate calculation processing in step S61. In step S62, the drawing mode of the endoscope shape model based on the endoscope shape model data is determined based on the input from the input unit provided in the endoscope device shape detection device 3.
The normal mode process of 63 is performed, and if the mode is the enlargement mode, the enlargement mode process of step S64 is performed and the process ends.

Then, in the normal mode processing, an endoscope shape model as shown in FIG. 24 is displayed on the monitor 25 of the endoscope device shape detection device 3.

In the enlargement mode processing, as shown in FIG.
In step S71, the operator operates the operation panel 24 to select a range to be enlarged on the monitor 25 (see FIG. 24) on which the endoscope shape model is displayed, and obtains, for example, upper left and lower right coordinates of the range. . Then, Step S72
It is determined whether or not the upper left and lower right coordinates selected in step S71 are the same. If they are the same, the enlargement range cannot be determined.
When the selected upper left and lower right coordinates are not the same, the process proceeds to step S73.

In step S73, the center of the current endoscope shape model is moved to the center of the selected range. Then, the range selected in step S74 is enlarged so as to be the same as the display window of the monitor 25, and the process ends.

As a result, the endoscope shape model displayed on the monitor 25 as shown in FIG. 24 is enlarged and displayed on the monitor 25 as shown in FIG.

In addition, an endoscope-shaped image image can be selected from the following models and displayed. That is, (1) 3D model 1 and 3D model 2 (2) 2D model (3) 12-point model (4) linear model

In the 3D model 1 and the 3D model 2, as shown in FIG. 27, by using a cubic function curve approximation and an interpolation method using a natural line, a cubic B-spline interpolation method or a quadratic B-spline interpolation method, The stereoscopic image of the endoscope shape is interpolated from the point coordinates of the coil to obtain normal vectors of two models at arbitrary coordinates of the source coil.

Then, as shown in FIG.
At 81, the surface ab shown in FIG.
A surface is drawn in the order of cd and surface cdef, and in step S82, the surface is shaded (smooth shading) using the respective normal vectors for each point, and an endoscope-shaped stereoscopic image is displayed.

Next, in step S83, the Z-axis coordinate in the depth direction when the monitor 25 plane is set to the XY plane is determined whether or not to perform color tone correction by gray scale in order to improve the stereoscopic effect. A color tone correction process is performed in step S84, and the process ends.

The color tone correction process in step S84 includes a first color tone correction process for performing color tone correction in the measurement range full scale of the endoscope device shape detection device 3 and a color tone correction process in the existing region full scale of the endoscope shape model. And a second color tone correction process.

In the first color tone correction process, as shown in FIG. 30, the maximum value and the minimum value of the measurement range are obtained in step S91, the color tone is calculated from the endoscope shape model data in step S92, and the process proceeds to step S93. A color that can be displayed is obtained from the color tone calculated in the above, and the color tone is corrected. As a result, as shown in FIG. 31, the color tone is corrected with the measurement range in the Z-axis direction being a full scale.

On the other hand, in the second tone correction processing, as shown in FIG. 32, the maximum value and the minimum value of the existing range of the endoscope shape model are obtained in step S95, and the endoscope shape model data is obtained in step S96. The color tone is calculated from
A color that can be displayed is obtained from the color tone calculated in the above, and the color tone is corrected. As a result, as shown in FIG. 33, color tone correction is performed with the existing range of the endoscope shape model as a full scale. That is, the second color tone correction processing performs finer color tone correction on the endoscope shape model than the first color tone correction processing.

In the 2D model of the endoscope-shaped image image, as shown in FIG. 34, a circle is drawn around each coordinate of the source coil in step S101 (the circle always faces the viewpoint direction). Then, in step S102, it is determined whether or not the color tone correction is to be performed. If so, the color tone correction process is performed in step S103, and the process is terminated.
5 displays an endoscope-shaped image image as shown in FIG.

In the 12-point model of the endoscope-shaped image, as shown in FIG. 36, all the position coordinates of the source coil are connected by a line in step S105, and
By drawing crosses at all points at 106 and ending the processing,
An image of an endoscope is displayed on the monitor 25 as shown in FIG.

Further, in the straight line model of the endoscope-shaped image image, as shown in FIG. 38, all the position coordinates of the source coil are connected by a line in step S108, and
At step 109, “black-filled squares” are drawn at all points, and the processing is terminated, whereby an image of an endoscope shape as shown in FIG. 39 is displayed on the monitor 25.

(Effects) As described above, in the present embodiment, a sense coil that accurately estimates the space where the source coil exists is selected from a plurality of sense coils arranged in a three-dimensional space. Since the three-dimensional position of the source coil is estimated, an accurate three-dimensional position of the source coil can be estimated.

Second Embodiment FIGS. 40 to 42 relate to a second embodiment of the present invention. FIG. 40 is an explanatory diagram for explaining the principle of a source coil estimated position coordinate calculating process, and FIG. 40 is a first flowchart showing the flow of the source coil estimated position coordinate calculation process of FIG. 40, and FIG. 42 is a second flowchart showing the flow of the source coil estimated position coordinate calculation process of FIG.

(Structure) The structure of the second embodiment is the same as that of the first embodiment, and differs from the first embodiment in the processing method for estimating the three-dimensional position of the source coil. Description is omitted.

(Operation) The circle where the source coil is estimated by one sense coil is represented by two nonlinear equations obtained by the single-core coils C _{S0 to} C _S2 and C _{S1 to} C _S3 as shown in FIG. A point satisfying (26) and (27) (x
_g , y _g ) is derived by the Newton method, and is calculated as a circle equation from the point (x _g , y _g ).

When the source coil and the sense coil approach each other, as shown in FIG. 40, there exist a plurality of intersections satisfying the equations (26) and (27), and the values of the initial values (x _g0 , y _g0 ) of the estimation system are obtained. Finds one of those intersections.

Now, assuming that the second intersection is found in FIG. 40, a circle where the source coil exists is found from the coordinate values of the second intersection.

[0153] When a circle is determined and the circle C ₁ shown in FIG. 18, obtains the circle C ₂ from the other sense coil, P point of closest on the two circumferential, source coil by calculating a P ' Can be determined.

At this time, if the second intersection is correct, the points P,
The distance between P ′ approaches 0, and if it is not correct, the points P,
Since the distance between P ′ is large, a combination of sense coils is determined such that the distance between points on the circumference of two circles estimated by the two sets of sense coils is the shortest. The three-dimensional position of the source coil is estimated from the coil.

FIGS. 41 and 42 show the flow of processing for estimating the three-dimensional position of the source coil.

As shown in FIG. 41, in steps S120 and S121, the order of the source coil 14i and the sense coil 22j is initialized.

First, the 0th source coil and the 0th sense coil are selected. In step S122, the voltages _V00 , _V01 , V1 generated in the four single-core coils of the 0th sense coil are selected. ₀₂ and V ₀₃ are taken in. In step S123, the 4 captured in step S122
It is determined whether all the voltages are 0 [V].

If all voltages are 0 [V] in step S123, the flag corresponding to the 0th sense coil is set to 0 in step S128, j is incremented in step S129, and step S122 is performed.
And the process proceeds to the processing of the first sense coil.

If all voltages are not 0 [V] in step S123, the flag corresponding to the 0th sense coil is set to 1 in step S124.

In the step S125, the position (x _g00 , y _g00 ) of the source coil on the plane formed by the 0th sense coil and the 0th source coil is calculated, and in the step S126, the source coil exists. Estimate the circle.

Now, since the processing of the 0th sense coil has been completed, step S127 is executed in step S1.
The process shifts to the process of 29, and j is incremented in step S129.

In step S127, it is detected that the processing has been completed for all the sense coils for the 0th source coil, and the flow advances to step S131 in FIG.

As shown in FIG. 42, in step S131, a sense coil whose flag is set to 1 is extracted, and
With respect to all the combinations of the sense coils thus extracted, a point on the circumference where two points on the circumference are closest and a distance between the two points are calculated.

The combination of the sense coils for which the distance calculated in step S131 is the shortest is determined in step S132.
In step S133, the three-dimensional position of the source coil is calculated from the two obtained sense coils.

A step S134 decides whether or not the processing has been performed on all the source coils. If the processing has not been performed on all the source coils, i is incremented at a step S130 in FIG. Step S1
21 and the processing is repeated until the processing is performed on all the source coils, and 3 of the 16 source coils are processed.
The dimension position is obtained, and the process ends.

(Effect) Since it is possible to determine whether the circle has been correctly estimated from the distance between points on the circumference of the two circles estimated by the two sets of sense coils, the source coil can be correctly determined even when the sense coil and the source coil are close to each other. Can be estimated.

Third Embodiment: FIGS. 43 to 45 relate to a third embodiment of the present invention. FIG. 43 is an explanatory diagram for explaining a source coil estimated position coordinate calculating process, and FIG. FIG. 45 is a first flowchart showing the flow of a source coil estimated position coordinate calculation process using two sense coils whose angles θ are close to orthogonal to each other. FIG. It is a 2nd flowchart which shows the flow of an estimated position coordinate calculation process.

(Structure) The third embodiment has the same structure as the first embodiment, and differs from the first embodiment in the processing method for estimating the three-dimensional position of the source coil. Description is omitted.

(Operation) In the present embodiment, the circle estimated by the sense coil composed of four single-core coils is
It is determined from the intersection condition of the two curves whether the determination is made with high accuracy, two sense coils are selected according to the result, and the three-dimensional position of the source coil is estimated.

The circle where the source coil exists, which is estimated by one sense coil, is represented by two nonlinear equations (26) obtained by the single-core coils C _{S0 to} C _S2 and C _{S1 to} C _S3 as shown in FIG. , (27) (x _g , y _g )
Is obtained by Newton's method.

At this time, x _{g of} the equations (26) and (27),
the partial derivative of y _g

(Equation 54)

[Equation 55] Distant, when the y _g is a function of x _g, the position (x _g, y _g) wherein in (26), the tangential vector of the curve represented by (27)

[Equation 56]

[Equation 57] It is expressed as Assuming that each normalized vector is ν ′ ₀ = (x ′ ₀ , y ′ ₀ ) (58) ν ′ ₃ = (x ′ ₃ , y ′ ₃ ) (59), the equations (26), (26) The angle θ at which the curve represented by 27) intersects is: cos θ = x ′ ₀ x ′ ₃ + y ′ ₀ y ′ ₃ (60)

As shown in FIG. 43, when the angle θ is small, the position where the angle intersects is easily affected by noise. Therefore, two sense coils whose angles θ are close to each other are selected, and the three-dimensional position of the source coil is determined. Ask.

FIGS. 44 and 45 show the flow of processing for estimating the three-dimensional position of the source coil.

As shown in FIG. 44, steps S140 and S141 initialize the order of the source coil 14i and the sense coil 22j.

[0175] First, the 0th source coil and 0th sensor coil selected in step S142, the voltage V ₀₀ generated in four single-core coil of the 0-th sense coil, V _01, V ₀₂ and V ₀₃ are taken in. In step S143, the 4 captured in step S142
It is determined whether all the voltages are 0 [V].

If all voltages are 0 [V] in step S143, the flag corresponding to the 0th sense coil is set to 0 in step S150, j is incremented in step S149, and step S142 is performed.
And the process proceeds to the processing of the first sense coil.

If all voltages are not 0 [V] in step S143, the flag corresponding to the 0th sense coil is set to 1 in step S144.

In step S145, the position (x _g00 , y _g00 ) of the source coil on the plane formed by the 0th sense coil and the 0th source coil is calculated, and in step S146, the position (x _g00 , y _g00 , y _g00 ) to determine the angle θ when the two curves intersect.

Now, since the processing of the 0th sense coil has been completed, step S147 is executed in step S1.
The process shifts to the process at 49, and j is incremented at step S149.

In step S147, it is detected that the processing has been completed for all the sense coils for the 0th source coil, and the flow advances to step S151.

In step S151, a sense coil whose flag is set to 1 is extracted, and two sense coils whose crossing angle θ is close to being orthogonal are selected from the extracted sense coils.

Then, as shown in FIG.
A step 152 detects whether or not the arrangement states of the two sense coils selected in the step S151 are orthogonal. If they are orthogonal, the procedure proceeds to the step S40, and otherwise proceeds to the step S41.

The process from step S40 to the end of the process is as described in the first embodiment (FIG. 2).
0 and FIG. 21).

(Effect) In this embodiment, since two sense coils which are less affected by noise or the like are selected from a plurality of sense coils constituted by four single-core coils, the three-dimensional position of the source coil can be accurately determined. Can be estimated well.

Fourth Embodiment: FIGS. 46 and 47 relate to a fourth embodiment of the present invention, and FIG. 46 is a diagram showing an example of an arrangement of source coils for generating a magnetic field in a three-dimensional space. FIG. 47 is a view for explaining the arrangement of the source coils of the fourth embodiment with respect to the arrangement of FIG.

(Structure) The structure of the fourth embodiment is the same as that of the first embodiment, except for the processing method for estimating the number and arrangement of the sense coils and the three-dimensional position of the source coil. Therefore, the same reference numerals are given and the description is omitted.

(Operation) In the present embodiment, the three-dimensional position of the source coil is not determined by the sense coil in which four single-core coils are combined, but a plurality of single-core coils are arranged in a three-dimensional space. The three-dimensional position of the source coil is estimated from the voltage generated in each single-core coil.

As shown in FIG. 46, one source coil for generating a magnetic field in the three-dimensional space XYZ is located at the position (x _g ,
y _g , z _g ) and orientation (g _x , g _y , g _z )
Suitable position _{P (x d, y d,} Z d) a magnetic field generated in the H _x, H
_y and _Hz are expressed as follows from Expression (14).

[0189]

[Equation 61] However, k _g is a constant, r is a distance between the source coil and the point P, the direction of the magnetic field H _x, H _y, H _z is X, Y, in the same direction and the Z-axis.

[0190] point coordinate X to the position of P, Y, Z and single-fiber coil C _x facing the same, if the C _y, is C _z are arranged, each of the single-core coil C _x, C _y, the C _z Generated voltage V _x , V
_y and V _z are

(Equation 62) Becomes Here, single core single core coil C _x is facing the X-axis, a coil axis and in the X-axis in the same direction when winding a conductive wire constituting the coil, the Y-axis, oriented the same as Z axis The coils C _y and C _z are similar coils.

Here, k _s is a constant determined by the size of the source coil and the sense coil, the number of turns of the coil, and the like.
Is the distance between the source coil and the sense coil

[Equation 63] It is.

As shown in FIG. 47, in the present embodiment,
A plurality of sense coils each composed of a single-core coil are arranged in a three-dimensional space. Specifically, in the bed 4, a sense coil 10 whose center Z coordinate is the first Z coordinate, for example, is directed to the X-axis.
1, 102, 103, and 104, sense coils 105, 106, 107, and 108 whose center Z coordinates are directed to the Y axis, which is a second Z coordinate different from the first Z coordinate, and whose center Z coordinate is The sense coils 109, 110, 111, 1 directed to the Z axis which is a third Z coordinate different from the first and second Z coordinates.
Twelve twelve sense coils are arranged. Since the voltages, positions, and directions of the twelve sense coils are all known, the position (x _g ,
y _g , z _g ) and orientation (g _x , g _y , g _z ) as unknowns 1
Two nonlinear equations are obtained.

The solution of these 12 nonlinear equations, that is, the position and orientation of the source coil are obtained by iterative improvement (Gauss-Newton method).

_Let x be the position of the source coil (x _g , y _g ,
z _g ) and orientation (g _x , g _y , g _z ) parameters, and the initial values of the parameters are x ⁽⁰⁾ .

Now, the k-th estimated value x ^{(k) is obtained} by iterative improvement.
Is obtained, and the model function V of the power generated in the sense coil is obtained.
When (X) is Taylor-expanded around x ^(k) , its first-order approximation is

[Equation 64] Becomes

At this time, if Vm is the voltage measured by the sense coil, the observation equation is

[Equation 65] Here, the reason why the expression is not equal but rather equal is that Vm includes a measurement error.

Are represented as follows. Moving the first term on the right side of equation (65) to the left side

[Equation 66] Becomes However,

ΔVm ^(k) = Vm−V (x ^(k) ) = Vm−Vm ^(k) (67)

Δx ^(k) = x−x ^(k) (68)

[Equation 69] (I = 1 to n, j = 1 to m) (row direction: number n of unknowns, column direction: number m of sense coils). The solution Δx ^(k) is given by equation (66)

Δx ^(k) = (B ^(k) WA ^(k) ) ⁻¹ B ^(k) WΔVm ^(k) (70) Here, B is the transposition of A, and W is the weight matrix.

Therefore, the parameter estimation value improved from the equation (68) is

X ^{(k + 1)} = x ^(k) + Δx ^(k) (71)

As shown in FIG. 47, when twelve single-core coils (sense coils) are arranged, the matrix A becomes

[Equation 72] The weight matrix W is

[Equation 73] It is expressed as Here, σ _i (i = 0, 1,
..., 11) are the fluctuations of the measured voltage of each sense coil.
For example, there is environmental noise.

The k-th ΔVm is

[Equation 74] Therefore, the position and orientation of the source coil can be obtained by the following procedures (1) to (4).

Procedure (1): k = 0, and the initial values of the source coil are set to the position (x _g , y _g , z _g ) ⁽⁰⁾ and the directions (g _x , g _y ,
g _z ) ⁽⁰⁾ (for example, the center position of the space for measuring the source coil and the vector (0, 0, 1) in the Z-axis direction). Procedure (2): Calculate the k-th matrix according to equations (72), (73), and (74). Procedure (3): k-th update amount Δx according to equation (71)
Calculate ^(k) . Procedure (4): The above procedures (2) to (4) are repeated until the update amount Δx ^(k) becomes small.

In this embodiment, the position of the source coil is estimated by arranging the sense coils oriented in the X, Y, and Z axis directions at the same height, but the present invention is not limited to this. Even if it is arranged at an arbitrary position or orientation, the position of the source coil can be estimated if the position and orientation of the sense coil are known.

When the space where the source coil exists is small, the position and orientation can be obtained by iteratively improving the initial value of the source coil as an appropriate position as described above. However, if the space is large, it is necessary to determine the initial position in an appropriate manner.

For example, in the case where the sense coils are arranged in a hollow shape as in the first embodiment, the sense coils are constituted by four single-core coils using the method described in the first to third embodiments. The space (circle) where the source coil exists is obtained from the sense coil obtained, the position of the source coil is estimated by a plurality of sense coils, and the position of the source coil can be obtained with high accuracy by iterative improvement.

Further, if the position estimation of the circle and the iterative improvement are performed on all the source coils 14i, the amount of calculation is increased. Therefore, the position estimation and the iterative improvement of the circle are performed on the head 14a of the source coil. For the source coil of (1), there is also a method of performing only the iterative improvement with the position previously estimated from the continuity of the source coil as an initial value (when estimating the three-dimensional position of the source coil 14b, Is performed using the estimated position of the source coil 14a as the initial value).

There is also a method of predicting the three-dimensional position of the source coil to be estimated from the three-dimensional position of the source coil previously estimated using the continuity of the source coil, and performing iterative improvement from the predicted position.

Now, the three-dimensional positions of the source coils 14a and 14b are

[Equation 75] Then, the initial value when estimating the three-dimensional position of the source coil 14b is set as the source coil 14a, and the position of the source coil is predicted from the source coil 14c from the three-dimensional positions of the two previous source coils.

For example, in the case of the source coil 14c

[Equation 76] And

In addition, since the present embodiment is used in a body cavity, it is expected that the three-dimensional position of the source coil has little fluctuation in the time direction (the movement of the source coil in the body cavity is small). There is also a method of performing iterative improvement using the three-dimensional position estimated up to the previous time as an initial position.

(Effect) In the present embodiment, the output of a plurality of sense coils and the three-dimensional position of the source coil are estimated by the iterative improvement method, so that the effects of noise and the like are reduced.
The estimation accuracy can be improved.

When the three-dimensional position of each source coil is estimated by iterative improvement, the amount of calculation can be reduced by obtaining the initial position by an appropriate method.

Fifth Embodiment (Configuration) The configuration of the endoscope shape detecting device 3 of the present embodiment is the same as that of the fourth embodiment, and the method of estimating the three-dimensional position of the source coil is different. different.

(Operation) In this embodiment, the three-dimensional position of the source coil is not determined by using a sense coil in which four single-core coils are combined, but a plurality of sense coils are provided in the same manner as in the fourth embodiment. The single-core coils are arranged in a three-dimensional space, and the three-dimensional position of the source coil is estimated from the voltage generated in each single-core coil.

Now, the matrix of the electromotive force generated in the sense coil in the sense coil unit is V, the matrix represented by the term of the three-dimensional position of the source coil and the sense coil as shown in the equation (62) is H, The term expressed by the direction of the source coil is G
Then, the respective relational expressions are as follows.

[0215]

[Number 77] V = HG ... (77) to erase the orientation of the section of the source coil from the equation (77), and applying a formula both sides (the transpose of the matrix H) H ^t from the left to the (77),

H ^t V = H ^t HG (78)

Also, on both sides of the equation (78), [H
^t H] ^-1 (the inverse of H ^t H),

[H ^t H] ⁻¹ H ^t V = G (79)

By substituting equation (79) into equation (77), the following equation in which the term of the direction of the source coil is eliminated can be obtained.

[0218]

V = H [H ^t H] ⁻¹ H ^t V (80) As shown in FIG. 47, in the present embodiment, a plurality of sense coils each composed of a single-core coil are arranged in a three-dimensional space. Specifically, in the bet 4, the sense coils 101 and 102 whose center Z coordinate is the first Z coordinate, for example, the X axis,
103, 104, and a sense coil 10 directed to the Y axis, which is a second Z coordinate whose center Z coordinate is different from the first Z coordinate.
5, 106, 107, and 108, and 12 of the sense coils 109, 110, 111, and 112 directed to the Z-axis that is a third Z-coordinate different from the first and second Z-coordinates.
The sense coils are arranged. Since the voltages, positions, and directions of the twelve sense coils are all known, the position (x _g , y _g , z _g ) of the source coil is _calculated by equation (62).
Are obtained as twelve nonlinear equations.

The solution of these 12 nonlinear equations, that is, the position of the source coil is obtained by iterative improvement (G
auss-Newton method).

X is the position of the source coil (x _g , y _g ,
z _g ), and the initial value of the parameter is x
⁽⁰⁾ .

Now, the k-th estimated value x ^{(k) is obtained} by iterative improvement.
Is obtained, and the model function V of the power generated in the sense coil is obtained.
When (x) is subjected to TayLor expansion around x ^(k) , the first-order approximation is expressed by Expression (64) shown in the fourth embodiment.

However, the term of the partial differential of the equation (64)

[Equation 81] Is obtained by inputting the value of the voltage Vm measured by the sense coil into V on the right side of equation (80).

The partial derivative is calculated as: V (x) = H [H ^t H] ⁻¹ H ^t Vm (82)

At this time, if Vm is the voltage measured by the sense coil, the observation equation is expressed by the equation (65) shown in the fourth embodiment. When the first term on the right side of Expression (65) is moved to the left side, Expression (66) shown in the fourth embodiment is obtained.

The solution Δx ^(k) is represented by equation (70) shown in the fourth embodiment from equation (66).

Therefore, the parameter estimation value improved from Δx ^(k) = x−x ^(k) can be ^obtained by the equation (7) shown in the fourth embodiment.
1) is required.

As shown in FIG. 47, when twelve single-core coils (sense coils) are arranged, the matrix A becomes

[Equation 83] The weight matrix W is represented by the equation (73) shown in the fourth embodiment. Where σ _i (i = 0, 1,...,
11) is a fluctuation amount of the measured voltage of each sense coil, for example, there is an environmental noise or the like.

Since the k-th ΔVm is given by the equation (74) shown in the fourth embodiment, the position of the source coil can be obtained by the following procedures (1) ′ to (4) ′. .

Procedure (1) ′; k = 0, and the initial value of the source coil is set to position (x _g , y _g , z _g ) ^{( 0)} (for example,
Center position of the space where the source coil is measured). Step (2) ′: The k-th matrix is calculated according to equations (83), (73), and (74). Procedure (3) ′: k-th update amount Δx according to equation (71)
Calculate ^(k) . Procedure (4) ′: The above procedures (2) ′ to (4) ′ are repeated until the update amount Δx ^(k) becomes small.

In this embodiment, the position of the source coil is estimated by arranging the sense coils oriented in the X, Y, and Z axis directions at the same height, but the present invention is not limited to this. Even if it is arranged at an arbitrary position or orientation, the position of the source coil can be estimated if the position and orientation of the sense coil are known.

When the space where the source coil exists is small, the position can be obtained by iteratively improving the initial value of the source coil as an appropriate position as described above. However, if the space is large, it is necessary to determine the initial position in an appropriate manner.

For example, in the case where the sense coils are arranged in a hollow shape as in the first embodiment, the sense coils are constituted by four single-core coils using the method described in the first to third embodiments. The space (circle) where the source coil exists is obtained from the sense coil obtained, the position of the source coil is estimated by a plurality of sense coils, and the position of the source coil can be obtained with high accuracy by iterative improvement.

Further, if the position estimation of the circle and the iterative improvement are performed on all the source coils 14i, the amount of calculation is increased. Therefore, the position estimation and the iterative improvement of the circle are performed on the head 14a of the source coil. For the source coil of (1), there is also a method of performing only the iterative improvement with the position previously estimated from the continuity of the source coil as an initial value (when estimating the three-dimensional position of the source coil 14b, Is performed using the estimated position of the source coil 14a as the initial value).

There is also a method in which the three-dimensional position of the source coil to be estimated is predicted from the three-dimensional position of the source coil previously estimated using the continuity of the source coil, and iterative improvement is performed from the predicted position.

As in the fourth embodiment, if the three-dimensional position of the source coils 14a and 14b is expressed by the equation (75) shown in the fourth embodiment, the three-dimensional position of the source coil 14b is determined.
The initial value for estimating the three-dimensional position is set to the source coil 14a.
From the source coil 14c, the position of the source coil is predicted from the three-dimensional position of the previous two source coils. For example, in the case of the source coil 14c, the equation (76) shown in the fourth embodiment is used.

Also, since the present embodiment is used in the body cavity, the three-dimensional position of the source coil is expected to have little variation in the time direction (the movement of the source coil in the body cavity is small). There is also a method of performing iterative improvement using the three-dimensional position estimated up to the previous time as an initial position.

(Effect) In the present embodiment, in addition to the effect of the fourth embodiment, the term of the direction of the source coil is deleted.
The three-dimensional position of the source coil can be estimated by the relational expression in which the unknowns are reduced.

Sixth Embodiment (Configuration) Although not shown, the endoscope shape detecting device 3 of the present embodiment has the same configuration as that of the first embodiment, and further includes an estimated source coil position. It is configured to have a position storage means for storing in time series. The other configuration is the same as that of the first embodiment. In the present embodiment, a processing method for estimating the three-dimensional position of the source coil is different from that of the first embodiment.

(Operation) In the present embodiment, the three-dimensional position of the source coil 14i is estimated by using the method described in the first to fifth embodiments, and stored in the position storage means (not shown). The estimated three-dimensional positions are sequentially stored.

The current position of the source coil 14i is

[Equation 84] And the past estimated position

[Equation 85] As the current source coil 1
The position P ′ _{i, n} of 4i is obtained by weighted addition.

Now _{, assuming} that the weight of the current estimated position is α, the current position P ′ _{i, n} of the source coil is

## EQU8 ## P ' _{i, n} = αP _{i, n-1} + (1−α) P _{i, n} (86)

In addition, X,
An intermediate value between the Y and Z components may be extracted and used as the current position of the source coil (median filter).

(Effect) According to the present embodiment, it is possible to suppress variations in the three-dimensional position of the source coil caused by the separation of the source coil and the sense coil.

Seventh Embodiment (Configuration) The configuration of the endoscope shape detecting device 3 of the present embodiment is the same as that of the sixth embodiment, and the method for estimating the three-dimensional position of the source coil is different. different.

(Operation) In the present embodiment, the source coil 1 is formed using the method described in the first to fifth embodiments.
Estimate the three-dimensional position of 4i, and store the position (not shown)
Are sequentially stored.

The estimated position of the source coil 14i stored in time series is

(87) _Let P _{i, 0} , P _{i, 1} , P _{i, 2} ,..., P _{i, N} ... (87) _denote the predicted position of the predicted source coil 14i.

(88) _Let Q _{i, 0} , Q _{i, 1} , Q _{i, 2} ,..., Q _{i, N} (88) (the N-th is the current position).

The sum of squares of the difference between the estimated position and the predicted position of the source coil 14i is

[Equation 89] And the sum of squares of the difference between the displacement amounts of adjacent predicted positions is

[Equation 90] And f _{i, 1} and f _{i, 2} are added with the following weight ω.

[0247]

F _i = f _{i, 1} + ωf _{i, 2} (91) Here, when the weight ω is reduced, the source coil 14i
Position approaches the estimated position. When the weight ω is increased, the position of the source coil 14i approaches the predicted position.

The predicted position Q _{i, j} that minimizes f _i is given by the expression f _i
Is partially differentiated at the predicted position Q _{i, j} to obtain a predicted position Q _{i, j} satisfying f ′ _i = 0.

F _i is partially differentiated at the predicted position Q _{i, j} , and f ′ _i =
0

P = MQ (92) is obtained, and the inverse matrix of the matrix is obtained.

By calculating Q = M ^-1 P (93), a predicted position is obtained.

For example, when the three-dimensional estimated positions up to seven positions before each source coil 14i are stored, the equation (92) becomes

[Equation 94] By setting the weight ω and calculating the inverse matrix of the matrix M, the predicted position is obtained from Expression (93).

(Effect) According to the present embodiment, the movement of the source coil is predicted from the estimated position of the source coil in the past.
Since it is obtained from the current position of the source coil based on the estimated position and the predicted position, the variation in the three-dimensional position of the source coil caused by the separation of the source coil and the sense coil is suppressed, and even when the source coil moves. A more stable position of the source coil than the method described in the fifth embodiment is obtained.

[Supplementary Note] (Supplementary Note 1) The magnetic field generating device includes a magnetic field generating means having a single axis transmitting coil for generating a magnetic field, and a magnetic field detecting means for detecting a magnetic field generated by the magnetic field generating means. In a position estimating device for detecting position information of the magnetic field generating means based on magnetic field detection by a detecting means, the magnetic field detecting means includes at least a first, second, third and fourth single-axis transmitting coils on a same straight line. And a fifth, sixth, seventh, and eighth single-axis transmission coil on a same straight line that is non-parallel to the first magnetic field detection unit. A position estimating device comprising: a second magnetic field detecting unit arranged in the same direction.

(Additional Item 2) A magnetic field generating means having a single axis transmitting coil for generating a magnetic field, and a magnetic field detecting means for detecting a magnetic field generated by the magnetic field generating means are provided. In a position estimating device for detecting position information of the magnetic field generating means based on a magnetic field detection, the magnetic field detecting means may include at least a first, a second, a third, and a fourth single-axis transmitting coil on a first straight line. A first magnetic field detection unit arranged in the same direction, and a fifth, sixth, seventh, and eighth single-axis transmitting coils arranged in a same direction on a second straight line parallel to the first straight line. And a ninth, tenth, eleventh, and twelfth single-axis transmitting coil in the same direction on a third straight line that is non-parallel to the first straight line. A third magnetic field detection unit disposed facing the third linear line and a fourth magnetic field detection unit parallel to the third straight line. The thirteenth, fourteenth, first
A position estimating device comprising: a fourth magnetic field detecting section in which fifth and sixteenth single-axis transmitting coils are arranged in the same direction.

(Additional Item 3) A source coil that generates a magnetic field by a single-core coil, a plurality of sense coils in which at least four single-core coils are arranged on the same straight line in the same direction,
Space sensing means for estimating the space where the source coil is located by the sense coil, and position estimating means for estimating the three-dimensional position of the source coil from the space where the source coil is located estimated by the space estimating means. In the position estimating apparatus, at least one set of the sense coils is arranged non-parallel to other sense coils.

(Additional Item 4) The position estimating device according to additional item 3, wherein the space estimating means comprises distance calculating means for calculating a distance to the source coil with the arrangement of the sense coils as an axis. .

(Additional Item 5) The additional item 3 is characterized in that the space estimating means is a circular area specifying means for specifying a circular area centered on the axis of the arrangement of the sense coils.
A position estimating device according to claim 1.

(Additional Item 6) The circular area specifying means is a circular area calculating means for calculating the circular area using a condition of a plane formed by the sense coil and the source coil. Item 6. The position estimation device according to item 5.

(Supplementary Note 7) The condition of the plane is a condition including an intersection point when at least two curves represented by three single-core coils of the sense coil are drawn on the plane, and 7. The position estimating apparatus according to claim 6, wherein the area calculating means calculates the intersection.

(Supplementary Item 8) The space estimating means obtains the maximum output of the single-core coil of each of the sense coils, extracts the sense coils in descending order of the maximum output, and the extraction means. The position estimating apparatus according to claim 3, further comprising: space estimating means for estimating a space where the source coil exists by the sense coil.

(Supplementary note 9) The position estimating means includes: extracting means for extracting at least two of the sense coils from the space estimated by the space estimating means; and the source of the sense coils extracted by the extracting means. The position estimating apparatus according to claim 3, further comprising: three-dimensional position estimating means for estimating a three-dimensional position of the source coil from a space where the coil exists.

(Supplementary note 10) The supplementary note 9, wherein the extraction means comprises sense coil extraction means for extracting at least two of the sense coils whose area of the space estimated by the space estimation means is small. The position estimating device according to the above.

(Additional Item 11) The position estimating means selects two circles from the plurality of circles estimated by the space estimating means, and determines a point on the circumference where the two circles are closest and a point between the points. A distance calculating means for calculating a distance, a detecting means for detecting a combination of the sense coils having a minimum distance calculated by the distance calculating means, and three of the source coils from the sense coils detected by the detecting means.
3. The position estimating apparatus according to claim 3, further comprising: three-dimensional position estimating means for estimating a three-dimensional position.

(Additional Item 12) The position estimating means may calculate at least two positions from the space estimated by the space estimating means.
Extracting means for extracting the three sense coils, and three-dimensional position estimating means for estimating a three-dimensional position of the source coil from a space where the source coil of the sense coil extracted by the extracting means exists. The position estimating apparatus according to claim 7, characterized in that:

(Additional Item 13) The extracting means detects an intersection state of a plurality of curves obtained from the plane condition of the space estimating means, and an intersection detected by the intersection state detecting means. Additional item 12 characterized by comprising sense coil extracting means for extracting at least two of said sense coils whose states are nearly orthogonal to each other.
A position estimating device according to claim 1.

(Additional Item 14) The direction of the source coil is estimated by using a direction estimating means for estimating a direction from the position of the source coil estimated by the position estimating means, and a result of the position estimating means and the direction estimating means. The position estimating device according to claim 3, further comprising estimating means for estimating the position and the direction.

(Supplementary Note 15) The estimating means includes a first output calculating means for calculating an output of the sense coil from a result of the position estimating means and the orientation estimating means, and a first output calculating means. From the calculated output of the sense coil and the measured output of the sense coil, update value calculation means for calculating values for updating the position and orientation of the source coil, respectively, and the update value calculation means Second output calculating means for adding the calculated update value to the position and orientation of the source coil and calculating the output of the sense coil; and the second output calculation means until the update value becomes an appropriate value. 15. The position estimating apparatus according to claim 14, further comprising: a source coil estimating means for estimating a position and an orientation of the source coil by repeating the output calculating means.

(Additional Item 16) Storage means for storing the position estimated by the position estimating means in time series, and a current position of the source coil is predicted from the position of the source coil stored in the storage means. 3. The position estimating apparatus according to claim 3, further comprising: a prediction unit that performs the prediction.

(Additional Item 17) The predicting means is characterized in that the position of the source coil stored in the storage means is weighted and added in time series to predict the current position of the source coil. Item 16. The position estimating device described in Additional Item 16.

(Additional Item 18) The predicting means comprises means for obtaining the movement of the source coil from the position of the source coil stored in the storage means and predicting the current position of the source coil. Appendix 16
A position estimating device according to claim 1.

(Additional Item 19) A source coil for generating a magnetic field by a single-core coil and a plurality of single-core coils as a sense coil in a three-dimensional space are arranged at different positions. A position estimating device comprising: estimating means for estimating a position and an orientation.

(Supplementary Item 20) The estimating means calculates the output of the sense coil from an appropriate position and orientation of the source coil by the first output calculating means and the first output calculating means. An output of the sense coil;
Update value calculation means for calculating a value for updating the position and orientation of the source coil from the measured output of the sense coil, and an update value calculated by the update value calculation means for the source coil. In addition to position and orientation,
The second output calculation means for calculating the output of the sense coil, and the update calculation means and the second output calculation means are repeated until the updated value becomes an appropriate value, and the position and orientation of the source coil are changed. 20. The position estimating apparatus according to claim 19, comprising a source coil estimating means for estimating.

(Supplementary note 21) The first output calculating means comprises setting means for setting the position and orientation of the source coil from the continuity of the arrangement of the source coils. Position estimation device.

(Additional Item 22) A storage means for storing the position and the orientation estimated by the estimation means in time series, and a position and an orientation of the source coil of the first output calculation means are stored in the storage means. 21. The position estimating apparatus according to claim 20, further comprising setting means for setting from the set position and orientation.

(Additional Item 23) A storage means for storing the position estimated by the estimating means in time series, and a current position of the source coil is predicted from the position of the source coil stored in the storage means. 20. The position estimation device according to claim 19, further comprising: a prediction unit.

(Additional Item 24) The predicting means is characterized in that the position of the source coil stored in the storage means is weighted and added in time series to predict the current position of the source coil. Item 23. The position estimating device according to additional item 23.

(Additional Item 25) The predicting means comprises means for obtaining the movement of the source coil from the position of the source coil stored in the storage means and predicting the current position of the source coil. Appendix 23
A position estimating device according to claim 1.

(Supplementary note 26) In a coil position measuring method for detecting the existence space of a source coil for generating a magnetic field, a magnetic field generating means having a single axis transmitting coil for generating a magnetic field, and a magnetic field generated by the magnetic field generating means Magnetic field detecting means for detecting the magnetic field generated by the magnetic field detecting means, and detecting the position information of the magnetic field generating means based on the magnetic field detection by the magnetic field detecting means, wherein the magnetic field detecting means is at least on a first straight line The first, which is arranged in the same direction,
A first magnetic field measuring step of measuring a magnetic field intensity generated by the source coil by a first magnetic field detecting unit including second, third and fourth uniaxial transmitting coils; The second, fifth, sixth, seventh, and eighth single-axis transmitting coils disposed in the same direction on the second straight line.
A second magnetic field measuring step of measuring the magnetic field intensity generated in the source coil by the magnetic field detecting section, and a second magnetic field measuring section arranged in the same direction on a third straight line that is non-parallel to the first straight line. A third magnetic field measuring step of measuring a magnetic field intensity generated in the source coil by a third magnetic field detecting unit including ninth, tenth, eleventh, and twelfth uniaxial transmitting coils; A fourth magnetic field detection unit including thirteenth, fourteenth, fifteenth, and sixteenth single-axis transmission coils arranged in the same direction on a fourth straight line parallel to
Measuring the intensity of the magnetic field generated by the source coil;
And a magnetic field measuring step.

(Supplementary Note 27) A magnetic field detecting unit extracting step of obtaining the maximum output of the single axis transmitting coil of each of the first to fourth magnetic field detecting units and extracting the magnetic field detecting units in descending order of the maximum output, 27. The coil position measuring method according to claim 26, further comprising: a space estimating step of estimating a space where the source coil exists by using the magnetic field detecting unit extracted in the magnetic field detecting unit extracting step.

(Supplementary Note 28) A space estimation step of estimating a space where the source coil exists based on the magnetic field strength measured by the first to fourth magnetic field measurement steps, and the source estimated by the space estimation step 27. The coil position measuring method according to claim 26, further comprising: a position estimating step of estimating a three-dimensional position of the source coil from a coil existing space.

(Additional Item 29) The additional space item 28, wherein the space estimating step includes a distance calculating step of calculating a distance to the source coil around the first to fourth straight lines as an axis. Coil position measurement method.

(Additional Item 30) The additional item 2 is characterized in that the space estimation step includes a circular area specifying step of specifying a circular area centered on the first to fourth straight lines.
9. The coil position measuring method according to 8.

(Supplementary Item 31) The circular area specifying step may include:
Item 3 is a circular region calculating step of calculating the circular region using a condition of a plane formed by the first to fourth magnetic field detecting units and the source coil.
0. The coil position measuring method according to item 0.

(Supplementary Note 32) The condition of the plane is that an intersection point when at least two curves represented by three single-axis transmitting coils of the first to fourth magnetic field detection units are drawn on the plane. Wherein the circle area calculating step calculates the intersection point.
2. The coil position measuring method according to 1. .

(Supplementary note 33) In the position estimating step, two circles are selected from the plurality of circles estimated in the space estimating step, and a point on the circumference where the two circles are closest and a point between the points are selected. A distance calculating step of calculating a distance, and the first to fourth steps in which the distance calculated by the distance calculating means is minimized.
A detecting step of detecting a combination of the respective magnetic field detecting sections, and a three-dimensional position estimating step of estimating a three-dimensional position of the source coil from the first to fourth magnetic field detecting sections detected in the detecting step. 29. The coil position measuring method according to claim 28, wherein

(Supplementary Item 34) The source coil is obtained by using a direction estimation step of estimating a direction from the position of the source coil estimated in the position estimation step, and a result of the position estimation step and the direction estimation step. Item 30. The coil position measuring method according to Item 28, further comprising an estimation step of estimating the position and the direction.

(Additional Item 35) A storing step of storing the position estimated in the position estimating step in time series, and a current position of the source coil is predicted from the position of the source coil stored in the storing step. 29. The coil position measuring method according to claim 28, further comprising:

(Supplementary Note 36) From the output of the sense coil configured by disposing a plurality of single-core coils at different positions in a three-dimensional space, the position and direction of the source coil that generates a magnetic field by the single-core coil are estimated. A coil position measuring method comprising an estimation step.

(Supplementary note 37) The estimating step is performed by a first output calculating step of calculating an output of the sense coil from an appropriate position and orientation of the source coil, and the first output calculating step. An output of the sense coil;
An update value calculation step of calculating values for updating the position and orientation of the source coil from the measured output of the sense coil, and an update value calculated in the update value calculation step. In addition to position and orientation,
A second output calculation step of calculating the output of the sense coil, and the update calculation step and the second output calculation step are repeated until the updated value becomes an appropriate value, and the position and orientation of the source coil are changed 37. The coil position measuring method according to claim 36, comprising a source coil estimating step of estimating.

(Supplementary Note 38) A source coil for generating a magnetic field by a single-core coil and a plurality of single-core coils in a three-dimensional space as sense coils are arranged at different positions. A position estimating device comprising: estimating means for estimating a position.

(Supplementary note 39) The estimating means includes first output calculating means for calculating the output of the sense coil from an appropriate position of the source coil, and the sense output calculated by the first output calculating means. Update value calculation means for calculating a value for updating the position of the source coil from an output of the coil and a measured output of the sense coil; and an update value calculated by the update value calculation means, The second output calculating means for calculating the output of the sense coil in addition to the position of the coil, and the update calculating means and the second output calculating means are repeated until the updated value becomes an appropriate value. Additional item 3 comprising source coil estimating means for estimating the position of the coil.
9. The position estimation device according to 8.

(Additional Item 40) The position according to Additional Item 39, wherein the first output calculating means comprises setting means for setting the position of the source coil from the continuity of the arrangement of the source coils. Estimation device.

(Additional Item 41) A storage means for storing the position estimated by the estimating means in a time-series manner,
40. The position estimating apparatus according to claim 39, further comprising: setting means for setting the position of said source coil of said output calculating means from the position stored in said storage means.

(Supplementary Note 42) From the output of a source coil that generates a magnetic field by a single-core coil and the output of a sense coil that detects the magnetic field formed by disposing a plurality of single-core coils at different positions in a three-dimensional space And a step of estimating the position of the source coil generating the magnetic field.

(Supplementary note 43) The estimating step includes a first output adding step of calculating an output of the sense coil from an appropriate position of the source coil, and the sensing output calculated by the first output adding step. An update value calculating step of calculating a value for updating a position of the source coil from an output of the coil and a measured output of the sense coil; and an update value calculated in the update value calculating step. In addition to the position of the coil, the second output addition step of calculating the output of the sense coil and the calculation in the update value calculation step and the second output addition step until the updated value becomes an appropriate value. 43. The coil position measuring method according to claim 42, further comprising a source coil position estimating step of repeatedly estimating the position of the source coil.

[0295]

According to the present invention as described above, according to the present invention, magnetic
The field detecting means includes at least a first axis on a predetermined first axis .
A first magnetic field detecting section in which second, third and fourth single-axis transmitting coils are arranged in the same direction;
A second magnetic field detecting unit in which fifth, sixth, seventh, and eighth single-axis transmitting coils are arranged in the same direction on a predetermined second axis that is a different axis ; About the axis, and
A first axis having a radius equal to a distance between the first axis and the magnetic field generation source;
Medium and the first calculating means for estimating the circumference, the second axis
Center and the distance between the second axis and the magnetic field source is half
A second calculation means for estimating a second circumference and diameter, the
The intersection of the first circumference and the second circumference, or the
1. On each circumference where the distance connecting the points on the second circumference is minimum
And the intersection or the distance is minimized
And means for estimating a magnetic field generating source on the basis of the point, and detects the position information of the magnetic field generating source based on the magnetic field detection by the magnetic <br/> field detecting means, a three-dimensional source coils by a plurality of sets of sense coils There is an effect that the estimation error when obtaining the position can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an endoscope system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration of the endoscope device shape detection device of FIG. 1;

FIG. 3 is a configuration diagram showing a configuration of the endoscope device shape detection device in FIG. 2;

4 is a diagram showing a main part 2 of the endoscope device shape detection device in FIG.
Configuration diagram showing the configuration of port memory and the like,

FIG. 5 is a timing chart showing the operation of the two-port memory of FIG. 4;

FIG. 6 is a flowchart showing the operation of the endoscope system of FIG. 1;

FIG. 7 is a flowchart showing the flow of the FFT processing of FIG. 6;

8 is a timing chart showing parallel processing timing in the operation of the endoscope system in FIG. 6;

FIG. 9 is a first explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process in FIG. 6;

FIG. 10 is a second explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process of FIG. 6;

FIG. 11 is a third explanatory view illustrating the principle of the source coil estimated position coordinate calculating process in FIG. 6;

FIG. 12 is a fourth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process in FIG. 6;

FIG. 13 is a fifth explanatory view illustrating the principle of the source coil estimated position coordinate calculating process in FIG. 6;

FIG. 14 is a sixth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process in FIG. 6;

FIG. 15 is a seventh explanatory view illustrating the principle of the source coil estimated position coordinate calculating process in FIG. 6;

FIG. 16 is an eighth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculation process in FIG. 6;

FIG. 17 is a ninth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculating process in FIG.

FIG. 18 is a tenth explanatory diagram illustrating the principle of the source coil estimated position coordinate calculating process in FIG. 6;

FIG. 19 is an eleventh explanatory diagram for explaining the principle of the source coil estimated position coordinate calculating process in FIG. 6;

20 is a first flowchart showing the flow of a source coil estimated position coordinate calculation process in FIG. 6;

FIG. 21 is a second flowchart showing the flow of the source coil estimated position coordinate calculating process in FIG. 6;

FIG. 22 is a flowchart showing the flow of a position update control process for the estimated source coil position calculated from FIGS. 20 and 21;

FIG. 23 is a flowchart showing the flow of an endoscope shape detection image display process of FIG. 6;

24 is a view showing a display example by the normal mode processing of FIG. 23;

FIG. 25 is a flowchart showing the flow of an enlargement mode process of FIG. 23;

FIG. 26 is a diagram showing a display example by the enlargement mode processing of FIG. 25;

FIG. 27 is a first explanatory diagram illustrating an image model of a 3D model 1 and a 3D model 2 in the endoscope shape detection image image display processing of FIG. 6;

28 is a flowchart showing the display processing of the image models of the 3D model 1 and the 3D model 2 in FIG.

FIG. 29 is a second explanatory diagram illustrating the image models of the 3D model 1 and the 3D model 2 in the endoscope shape detection image image display processing of FIG. 6;

30 is a first flowchart showing the flow of the color tone correction processing of FIG. 29.

FIG. 31 is a first example for explaining the operation of the color tone correction processing of FIG. 30;
Illustration of

FIG. 32 is a second flowchart showing the flow of the color tone correction process of FIG. 29;

FIG. 33 is a second diagram illustrating the operation of the color tone correction processing in FIG. 30;
Illustration of

FIG. 34 is a flowchart showing a display process of an image model of a 2D model in the endoscope shape detection image image display process of FIG. 6;

FIG. 35 is a diagram showing a display example of an endoscope shape detection image image displayed in the processing shown in FIG. 34;

FIG. 36 is a flowchart showing a display process of a 12-point model image model in the endoscope shape detection image image display process of FIG. 6;

FIG. 37 is a diagram showing a display example of an endoscope shape detection image image displayed by the processing in FIG. 36;

FIG. 38 is a flowchart showing a display process of an image model of a straight line model in the endoscope shape detection image image display process of FIG. 6;

FIG. 39 is a diagram showing a display example of an endoscope shape detection image image displayed in the processing shown in FIG. 38;

FIG. 40 is an explanatory diagram illustrating the principle of a source coil estimated position coordinate calculation process according to the second embodiment of the present invention.

FIG. 41 is a first flowchart showing the flow of a source coil estimated position coordinate calculation process in FIG. 40;

FIG. 42 is a second flowchart showing the flow of the source coil estimated position coordinate calculating process of FIG. 40;

FIG. 43 is an explanatory diagram illustrating source coil estimated position coordinate calculation processing according to the third embodiment of the present invention.

44 is a first flowchart showing a flow of a source coil estimated position coordinate calculating process by two sense coils in which the angle θ in FIG.

45 is a second flowchart showing the flow of a source coil estimated position coordinate calculation process by two sense coils in which the angle θ is nearly orthogonal in FIG. 43;

FIG. 46 is a diagram showing an example of an arrangement of source coils for generating a magnetic field in a three-dimensional space according to the fourth embodiment of the present invention.

FIG. 47 is a view for explaining the arrangement of the source coils of the fourth embodiment with respect to the arrangement of FIG. 46;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Endoscope system 2 ... Endoscope apparatus 3 ... Endoscope shape detection apparatus 4 ... Bed 6 ... Electronic endoscope 7 ... Insertion part 8 ... Operation part 9 ... Universal code 10 ... Video processor 11 ... Image observation Monitor 12 ... Forceps channel 12a ... Insertion port 14i ... Source coil 15 ... Probe 16 ... Source cable 21 ... Device body 22k ... Single core coil 22j ... Sense coil 23 ... Sense cable 24 ... Operation panel 25 ... Monitor 26 ... Drive block 27 ... Detection block 28 Host processor 31 Source coil drive circuit 32 CPU 33 PIO 34 Sense coil signal amplifier circuit 35 k Amplifier circuit 36 k Filter circuit 37 k Output buffer 38 k ADC 40 Control signal generator circuit 41 Local data bus 42 ... 2-port memory 46 ... internal bus 47 ... main memory 48 ... video RAM 49 ... video signal generating circuit

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B ⁷ /00-7/34 102 A61B 1/00-1/32 G02B 23/24-23/26

Claims (3)

(57) [Claims] 1. A magnetic field source having a single axis transmitting coil for generating a magnetic field, and magnetic field detecting means for detecting a magnetic field generated by the magnetic field generating source, wherein the magnetic field detecting means detects a magnetic field. In the position estimating apparatus for detecting position information of the magnetic field generating source based on the first, second, third and fourth single-axis transmitting coils on at least a predetermined first axis, A first magnetic field detector arranged in the direction, and a fifth, sixth, seventh, and eighth single-axis transmission on a predetermined second axis different from the first axis. A second magnetic field detecting unit in which coils are arranged in the same direction; a first circle having the first axis as a center and having a radius between the first axis and the magnetic field generating source as a radius First calculating means for estimating a circumference; and the second axis and the magnetic field centered on the second axis. A second calculating means for estimating a second circumference having a radius corresponding to a distance from the source, and an intersection of the first circumference and the second circumference, or the first and second circumferences Means for determining a point on each circumference at which the distance connecting the above points is the smallest, and estimating a magnetic field source based on the intersection or the point at which the distance is the smallest. Estimation device. 2. A magnetic field source having a single-axis transmission coil for generating a magnetic field, and magnetic field detecting means for detecting a magnetic field generated by the magnetic field generating source, wherein the magnetic field detecting means detects a magnetic field. In the position estimating apparatus for detecting position information of the magnetic field generating source based on the first, second, third and fourth single-axis transmitting coils on at least a predetermined first axis, A first magnetic field detector arranged in the direction, and a fifth, sixth, seventh, and eighth single-axis transmission on a predetermined second axis different from the first axis. A second magnetic field detection unit in which coils are arranged in the same direction; and a magnetic field generation source and the first magnetic field generation unit based on an output of the first magnetic field detection unit that receives a magnetic field from the magnetic field generation source. A plurality of curves are calculated assuming a plane including the magnetic field detection unit, and the plurality of curves are calculated. First, a curve whose crossing state is close to orthogonal is obtained, and a first circle having the first axis as a center and the radius between the first axis and the magnetic field generating source as a radius based on the curve. First calculating means for estimating a circumference; and a plane including the magnetic field generating source and the first magnetic field detecting unit based on an output of the first magnetic field detecting unit receiving a magnetic field from the magnetic field generating source. Assuming a plurality of curves, among the plurality of curves, obtain a curve whose crossing state is nearly orthogonal, based on the curve, centering on the second axis, and A second calculating means for estimating a second circumference having a radius equal to a distance from the magnetic field generation source; and an intersection of the first circumference and the second circumference, or the first and second circumferences. The point on each circumference where the distance connecting the points on the circumference of the circle is minimum is obtained, and based on the intersection or the point where the distance is the minimum, Position estimation device characterized by comprising: means for estimating a magnetic field generating source. 3. The method according to claim 1, wherein the estimation of the position of the magnetic field source by the magnetic field detection unit is repeated, and the current position of the magnetic field source is estimated based on the estimated position calculated in the past and the latest estimated position. Item 3. The position estimation device according to item 2.