Micro electromagnetic positioning method and system and storage medium thereof

Abstract

The invention discloses a micro-electromagnetic positioning method and system and a storage medium thereof. The method comprises the steps that sine wave current with fixed frequency sequentially, circularly and alternately passes through three groups of magnetic source micro-electromagnetic coils in sequence to excite sine wave magnetic fields in three dimensions; acquiring magnetic field data information of a positioning target in the sine wave magnetic field, and acquiring the magnetic field data information of the positioning target in the corresponding sine wave magnetic field based on the fact that one group of magnetic source micro electromagnetic coils are electrified each time, the magnetic field data information comprises a three-dimensional magnetic field component sensed by the positioning target in the sine wave magnetic field; fitting the three-dimensional magnetic field component of each dimension, and decomposing the three-dimensional magnetic field component to obtain independent magnetic field signals of three groups of magnetic source micro electromagnetic coils at the positioning target; and obtaining the position and attitude information of the positioning target according to the independent magnetic field signal. According to the invention, three-dimensional sine wave magnetic fields with fixed frequency can be excited circularly and alternately, so that a positioning target can generate three-dimensional data to facilitate positioning calculation. In addition, a function fitting mode is adopted to assist in positioning calculation, after n-point data fitting, the standard deviation of an equivalent magnetic field measurement value can be reduced to # imgabs0 # of a direct measurement result, the signal-to-noise ratio is remarkably improved, superimposed magnetic field signal data with high accuracy are extracted, and the precision of a positioning system can be improved. According to the positioning method, the system is high in anti-interference capability, the calculation result is more accurate, the overall power consumption is low, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromagnetic positioning technology, and in particular to a micro-electromagnetic positioning method, system and storage medium thereof. Background Art

[0002] Capsule endoscopes are widely used in medical examinations and auxiliary diagnosis of the digestive tract. The digestive tract environment is tortuous and there are many factors that affect intestinal peristalsis, which leads to large individual differences in the movement time and process of the capsule endoscope in the digestive tract. The movement speed of the capsule in the digestive tract is uneven, and there are often local displacements and posture changes, which are also affected by digestive tract peristalsis and body movement. It is difficult to accurately establish the three-dimensional structure of the digestive tract and locate the physical position of the lesion only through the visual images taken by the capsule endoscope. Using magnetic positioning technology to position the capsule endoscope in the body can obtain the spatial position and posture information of the capsule in addition to the capsule image, which may help establish the three-dimensional structure of the digestive tract and locate the physical position of the lesion.

[0003] The existing magnetic positioning technologies for capsule endoscopes in the human body either require the human body to stay near a fixed positioning device, or the positioning device wraps most of the torso to affect human movement, or the high power consumption limits the sustainable positioning time or the timeliness of positioning, or the poor positioning accuracy makes it difficult to distinguish the overlapping small intestinal intestinal paths. The above magnetic positioning technologies have more or less defects such as poor portability, high energy consumption, low positioning frequency, and unsatisfactory positioning accuracy.

[0004] The existing magnetic positioning technology for capsule endoscopes in the human body mainly uses square wave pulse current to pass through the magnetic source coil to generate a corresponding square wave pulse magnetic field. The square wave pulse magnetic field has high power consumption and insufficient positioning endurance, which cannot meet the actual positioning needs. At the same time, it takes a certain amount of time for the square wave type sudden power supply to reach stability, that is, there is a step-like sudden change in the coil power supply (in fact, affected by the induced magnetic field, the current and magnetic field cannot change suddenly, but require a delay process, corresponding to the delay time), resulting in a long waiting time to measure the stable magnetic field amplitude, that is, the positioning cycle is long. On the one hand, it cannot meet the positioning frame rate requirements. On the other hand, due to the long positioning cycle, if the positioning target moves within a positioning cycle. The range is large, it will cause a large positioning error. In the prior art, there is also a method of using non-stationary curve characteristics to calibrate the curve transformation coefficient to obtain the amplitude of the square wave magnetic field. Although this can shorten the positioning cycle, the square wave amplitude error obtained is large, which ultimately leads to inaccurate positioning.

[0005] In the existing magnetic positioning technology for capsule endoscopes in the human body, in order to effectively reduce the power consumption of the square wave pulse magnetic field signal of the magnetic source and the negative impact of the square wave-like mutation magnetic field on the positioning accuracy, positioning technologies with sinusoidal magnetic field signals as the magnetic source have emerged one after another. Each independent sinusoidal magnetic field signal is obtained through Fourier decomposition, and then the position and posture of the positioning target are solved.

[0006] On the one hand, when the positioning target is far away from the magnetic source, the magnetic field measurement values ​​measured by the magnetic sensor of the positioning target are widely dispersed and the signal-to-noise ratio is low. Directly using the magnetic field measurement values ​​measured by the magnetic sensor of the positioning target for decomposition results in large noise and low positioning accuracy.

[0007] On the other hand, the positioning method of obtaining each independent sinusoidal magnetic field signal through Fourier decomposition has a very complex solution process, and has high requirements on the signal frequency setting of the magnetic source coil. For example, the signal frequency of the magnetic source coil is in multiple relationship, so that the highest signal frequency f of the magnetic source coil k Large, and the maximum sampling frequency f of the magnetic sensor s is limited, which results in an inability to obtain enough samples n (n≤f s / f k ), so the measured value of the magnetic sensor cannot accurately restore the actual magnetic field value, which ultimately leads to low positioning accuracy. In order to obtain an independent signal with higher accuracy through Fourier decomposition, it is necessary to obtain a sufficient number of samples. Obviously, it is impossible to obtain such a large number of samples in one cycle. Therefore, Fourier decomposition requires multiple periodic signals, that is, the required positioning cycle is longer. If the range of movement of the positioning target is large within one positioning cycle, it will lead to a large positioning error.

[0008] In summary, the existing magnetic positioning technology cannot meet the actual positioning requirements of capsule endoscopes. Summary of the invention

[0009] The purpose of the present invention is to provide a micro-electromagnetic positioning method, system and storage medium thereof to solve the technical problems in the prior art that the magnetic positioning technology of capsule endoscopes has high power consumption, poor positioning accuracy, long positioning solution time and poor timeliness.

[0010] To achieve one of the above-mentioned purposes, an embodiment of the present invention provides a micro-electromagnetic positioning method, the method comprising:

[0011] A sinusoidal current of a fixed frequency is used to circulate alternately through three groups of magnetic source micro-electromagnetic coils in sequence to excite a three-dimensional sinusoidal magnetic field.

[0012] The magnetic field data information of the positioning target in the sinusoidal magnetic field is obtained, and the magnetic field data information of the positioning target in the corresponding sinusoidal magnetic field is obtained based on each time a group of the magnetic source micro-electromagnetic coils are energized, wherein the magnetic field data information includes the three-dimensional magnetic field components sensed by the positioning target in the sinusoidal magnetic field.

[0013] The three-dimensional magnetic field component of each dimension is fitted, and decomposed to obtain independent magnetic field signals of three groups of magnetic source micro-electromagnetic coils at the positioning target.

[0014] As a further improvement of the present invention, the method further comprises:

[0015] The frequency of the sinusoidal current is fixed to satisfy f ps ≤f≤f s / n, where f ps is the full-load positioning frame rate of the positioning system, f s is the sampling frequency of the magnetic sensor, and n is the number of samples that can be achieved within one cycle of a sinusoidal wave signal.

[0016] As a further improvement of the present invention, the method further comprises:

[0017] The fitting of the three-dimensional magnetic field component of each dimension specifically includes: performing function fitting on the magnetic field measurement values ​​of the dispersed three-dimensional magnetic field components to obtain the magnetic field intensity B in the corresponding dimension k；s (t);

[0018] The decomposition to obtain the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target includes: the magnetic field strength B after decomposition and fitting k；s (t), obtain the magnetic induction intensity amplitude A of the independent magnetic field signals of the three groups of magnetic source micro electromagnetic coils at the positioning target k；s , the decomposition formula is:

[0019] B k；s (t) = A k；s sin(wt+b)+c k；s ;

[0020] Wherein, k represents the serial number of the magnetic source micro-electromagnetic coil, k=1, 2, 3; s=1, 2, 3, represents the three dimensions of the sinusoidal magnetic field, representing the X direction, the Y direction, and the Z direction respectively; A k；s is the magnetic induction intensity amplitude of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target to be determined and decomposed, that is, the magnetic field measurement peak value; c k；s is the background magnetic field component when each group of magnetic source micro-electromagnetic coils is energized respectively; the signal angular frequency w and the signal phase b are known quantities directly obtained according to the frequency value and phase value of the current data.

[0021] As a further improvement of the present invention, the method further comprises:

[0022] The decomposition formula is linearized to obtain the linearized decomposition formula:

[0023]

[0024] Among them, β 0；k；s X 0；k；s Characterizes the environmental magnetic field strength at the positioning target when the three groups of magnetic source micro electromagnetic coils are powered on respectively; β 1；k；s X 1 Characterize the three-dimensional magnetic field strength of the magnetic field signal at the positioning target when the three groups of magnetic source micro-electromagnetic coils are powered on respectively, that is, the three-dimensional magnetic field strength of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target;

[0025] Using a series of data at time t, {X j；k；s (t),B j；k；s (t)}, and solve the coefficient β through linear optimization j；k；s After that, it is easy to calculate the required magnetic induction intensity amplitude A k；s and background magnetic field c k；s .

[0026] As a further improvement of the present invention, the method further comprises:

[0027] The magnetic induction intensity amplitude A k；s Correction is performed, and the correction formula is Where Ik0 is the initial hardware parameter current peak value under ideal working conditions, Ik1 is the current peak value under actual working conditions, A 0；k；s is the magnetic field strength B after decomposition fitting k；s (t) The magnetic induction intensity amplitude A obtained k；s , A 1；k；s For the A 0；k；s The magnetic induction intensity amplitude is obtained after correcting the resistance and current change drift caused by the coil temperature change and the actual magnetic field intensity.

[0028] As a further improvement of the present invention, the method further comprises:

[0029] The magnetic induction intensity amplitude A k；s The matrix is ​​updated using a cyclic refresh mechanism, with 1x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the same set of coils is energized.

[0030] As a further improvement of the present invention, the method further comprises:

[0031] The magnetic induction intensity amplitude Ak；s The matrix is ​​updated using a cyclic refresh mechanism, with 3x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the three sets of coils are energized.

[0032] As a further improvement of the present invention, the method further comprises:

[0033] Acquiring the position and attitude information of the positioning target according to the independent magnetic field signal specifically includes:

[0034] The spatial distribution of magnetic induction intensity is simplified by using the magnetic dipole approximation. The calculation formula for the peak value of magnetic induction intensity is:

[0035]

[0036] Among them, μ 0 is the vacuum magnetic permeability; M k is the peak value of the equivalent magnetic moment after the kth coil is energized, is the unit vector of the equivalent magnetic moment of the kth coil, k = 1, 2, 3; is the spatial position vector; is the spatial position unit vector;

[0037] According to the peak value of magnetic induction intensity Obtain the theoretical value of the magnetic induction intensity peak matrix

[0038] The position and attitude information of the positioning target is obtained by solving the corresponding relationship between the theoretical value of the magnetic induction intensity peak matrix and the magnetic field measurement peak in the independent magnetic field signal through a nonlinear optimization algorithm; wherein the corresponding relationship is:

[0039]

[0040] in, A is the sensor attitude rotation matrix; k；s is the peak value of the magnetic field measurement; is the theoretical value of the magnetic induction intensity peak matrix;

[0041] The nonlinear optimization algorithm is:

[0042]

[0043] As a further improvement of the present invention, the method further comprises:

[0044] The pitch angle pitch and the roll angle roll of the positioning target are obtained, and the yaw angle yaw and the position coordinates of the positioning target are calculated according to the pitch angle pitch, the roll angle roll of the positioning target and the independent magnetic field signal.

[0045] As a further improvement of the present invention, the method further comprises:

[0046] The positioning target includes at least one main positioning target and N auxiliary positioning targets. The micro-electromagnetic positioning method also includes a positioning calibration method, and the specific steps include:

[0047] Calculate the position information of N (N≥2) auxiliary positioning targets multiple times within a preset time length and calculate the average position of the N (N≥2) auxiliary positioning targets;

[0048] Calculating the position information of the main positioning target and the position information of the N (N≥2) auxiliary positioning targets after a preset time period;

[0049] Construct a scaling and rotation change matrix W*S to calibrate the position information of the main positioning target in the target detection area.

[0050] As a further improvement of the present invention, the method further comprises:

[0051] It is characterized in that the position information of N (N≥2) auxiliary positioning targets is calculated multiple times within a preset time period and is obtained when the human body is in an upright standard posture, and the preset time period is 1 minute.

[0052] As a further improvement of the present invention, the method further comprises:

[0053] The construction of the scaling and rotation change matrix W*S satisfies Solve the transformation matrix by pseudo-inverse operation

[0054] in, The D N1 The position information of N (N≥2) auxiliary positioning targets obtained by multiple calculations within the preset time length, The set matrix of average positions of N (N≥2) auxiliary positioning targets is obtained by calculating the position information of N (N≥2) auxiliary positioning targets for multiple times within the preset time length; The D N2 is the location information of N (N≥2) auxiliary positioning targets calculated after the preset time period, is a collection matrix of position information of N (N≥2) auxiliary positioning targets calculated after the preset time length;

[0055] The calibrating the position information of the main positioning target in the target detection area specifically includes calibrating the position information C2 of the main positioning target calculated after the preset time length to obtain new position information C, satisfying C=W·S·C 2 .

[0056] As a further improvement of the present invention, the method further comprises:

[0057] The number of auxiliary positioning targets N=2, 3, 4.

[0058] In order to achieve one of the above-mentioned objects, the present invention further provides a micro-electromagnetic positioning system, the system comprising:

[0059] A magnetic field generating component, comprising three groups of magnetic source micro-electromagnetic coils arranged on an excitation magnetic core, wherein the magnetic source micro-electromagnetic coils are used to receive a sinusoidal current and generate a three-dimensional sinusoidal magnetic field;

[0060] A positioning target includes a three-dimensional magnetic sensor for receiving the sinusoidal magnetic field and sensing a three-dimensional magnetic field component;

[0061] A positioning processing component, electrically connected to the magnetic field generating component and the positioning target;

[0062] The positioning processing component is configured to implement the micro-electromagnetic positioning method as described above.

[0063] As a further improvement of the present invention, the system further comprises:

[0064] The three groups of magnetic source micro-electromagnetic coils are orthogonal to each other, and their centers coincide with the center of the excitation magnetic core.

[0065] As a further improvement of the present invention, the system further comprises:

[0066] It also includes a waist belt, a fixing belt and a connecting cable bundle, the positioning target includes at least a main positioning target and N auxiliary positioning targets, the N auxiliary positioning targets are spaced apart from the magnetic field generating component on the waist belt to form a target detection area, the positioning processing component is installed on the fixing belt, the positioning processing component is electrically connected to the magnetic field generating component through the connecting cable bundle, and excites the magnetic field generating component to generate a three-dimensional sinusoidal wave magnetic field, and the main positioning target is located in the target detection area.

[0067] As a further improvement of the present invention, the system further comprises:

[0068] The fixing strap is a leg strap, and the positioning processing component is installed on the leg strap.

[0069] The present invention also provides a storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the micro-electromagnetic positioning method as described above are implemented.

[0070] Compared with the prior art, the present invention has the following beneficial effects: the present invention can cyclically and alternately excite a three-dimensional sinusoidal magnetic field with a fixed frequency, so that the positioning target can generate three-dimensional data for easy positioning and solution. The present invention also uses function fitting to assist positioning and solution. After n-point data fitting, the standard deviation of the equivalent magnetic field measurement value can be reduced to the direct measurement result. The signal-to-noise ratio is significantly improved, and the superimposed magnetic field signal data with high accuracy is extracted, which can improve the accuracy of the positioning system. The positioning method and system of the present invention have strong anti-interference ability, more accurate solution results, lower overall power consumption and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a flow chart of a micro-electromagnetic positioning method in one embodiment of the present invention.

[0072] Figure 2 It is a flow chart of fitting magnetic field data information and decomposing it to obtain independent magnetic field signals in one embodiment of the present invention.

[0073] Figure 3 It is an exemplary typical magnetic field data characteristic diagram in one embodiment of the present invention.

[0074] Figure 4 is a characteristic diagram of the magnetic field component in one embodiment of the present invention.

[0075] Figure 5 The timing control logic of the non-interval cyclic alternating power supply in one embodiment of the present invention is shown in the figure.

[0076] Figure 6 This is a timing logic diagram of power-on control for long-interval cyclic alternating power supply in one embodiment of the present invention.

[0077] Figure 7 This is a timing logic diagram of power-on control for short-interval cyclic alternating power supply in one embodiment of the present invention.

[0078] Figure 8 It is a flow chart for solving the position and posture information of the positioning target in one embodiment of the present invention.

[0079] Fig. 9 It is a positioning calibration flow chart in one embodiment of the present invention.

[0080] Fig.10 It is a schematic structural diagram of a micro-electromagnetic positioning system in one embodiment of the present invention.

[0081] Fig.11 Schematic diagram of a waist belt of a micro-electromagnetic positioning system in one embodiment of the present invention.

[0082] Fig.12It is a schematic diagram of the position change of N auxiliary positioning target calibrations in one embodiment of the present invention.

[0083] Fig.13 It is a schematic diagram of the structure of a magnetic field generating component in one embodiment of the present invention.

[0084] Fig.14 This is a schematic diagram of the overall structure connection of the micro electromagnetic positioning system in one embodiment of the present invention.

[0085] Fig.15 It is a computer system structure block diagram of the storage medium suitable for implementing the implementation mode of the present application in the present invention. DETAILED DESCRIPTION

[0086] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0087] like Figure 1 As shown, in one embodiment of the present invention, a micro-electromagnetic positioning method is provided, which can be applied to the positioning of capsule endoscopes during gastrointestinal medical examinations and auxiliary diagnosis. A target detection area is formed by a sinusoidal magnetic field of the micro-electromagnetic positioning method, and the capsule endoscope is located and active in the target detection area. The micro-electromagnetic positioning method can calculate the position and posture of the capsule endoscope in the target detection area; wherein, the capsule endoscope is identified as a positioning target in the target detection area.

[0088] Specifically, the micro-electromagnetic positioning method includes:

[0089] S1: A fixed-frequency sinusoidal current is used to circulate alternately through three groups of magnetic source micro-electromagnetic coils in sequence to excite a three-dimensional sinusoidal magnetic field.

[0090] S2: Acquire the magnetic field data information of the positioning target in the sinusoidal magnetic field, and acquire the magnetic field data information of the positioning target in the corresponding sinusoidal magnetic field each time a group of the magnetic source micro-electromagnetic coils are energized, wherein the magnetic field data information includes the three-dimensional magnetic field components sensed by the positioning target in the sinusoidal magnetic field.

[0091] S3: Fitting the three-dimensional magnetic field component of each dimension, and decomposing to obtain independent magnetic field signals of three groups of magnetic source micro-electromagnetic coils at the positioning target.

[0092] S4: Obtaining the position and posture information of the positioning target according to the independent magnetic field signal.

[0093] In step S1, the positioning method cyclically and alternately excites three groups of magnetic source micro-electromagnetic coils to generate three-dimensional sinusoidal magnetic fields respectively. The sinusoidal magnetic fields of the three groups of magnetic source micro-electromagnetic coils excite the positioning target in different time periods to generate magnetic field data information, so that the magnetic field data information of each dimension can be separated in the generation stage for easy distinction, which is more conducive to subsequent calculations; at the same time, the amount of calculation during positioning solution can be reduced, thereby saving solution time and reducing solution power consumption; during the solution process, the anti-interference ability is strong, background interference can be eliminated, the data accuracy is high, and the distortion rate is low, so the real-time positioning performance is better during repeated positioning.

[0094] Three sets of mutually orthogonal, center-coincident magnetic source coils circulate and alternately apply sinusoidal current of a specific frequency.

[0095] I(t)=asin(wt+b),

[0096] Where a is the current peak value, w=2πf is the sine wave angular frequency, f is the sine wave frequency, and b is the sine wave phase. The peak value a and frequency f of the sine wave current are preset fixed values ​​of the hardware system.

[0097] The magnetic induction intensity vector of the sinusoidal magnetic field generated by the sinusoidal current passing through the coil is

[0098]

[0099] in, is the peak vector of magnetic induction intensity (including the three-axis magnetic field components in space), and k is the coil serial number (k=1, 2, 3, corresponding to the three groups of X, Y, and Z coils that are orthogonal to each other).

[0100] There is an optimized value for the initial phase of the sine wave. Usually, the phase of the sine wave can be set to b=0 through hardware control (in fact, b=nπ can also achieve the same effect, but b=0 is simpler and more natural), so that after each set of coils undergoes a complete cycle of power-on, it switches to the next set of coils for power supply, and the initial phase of the current is also 0. This processing method can reduce the sudden change of coil current caused by switching coil power supply due to non-zero initial phase, and reduce the distortion of the waveform of the magnetic field generated by the magnetic source coil to a certain extent.

[0101] The sine wave frequency f has a reasonable range of values, satisfying f ps ≤f≤f s / n. The lower limit of the sine wave frequency f is subject to the full-load positioning frame rate f of the positioning system. ps For example, if the positioning system wants to achieve a full-load positioning frame rate of 20fps, the sine wave frequency f must be no less than 20Hz. The upper limit of the sine wave frequency f is limited by the magnetic sensor sampling frequency f. s Limit, f≤f s / n, to ensure that n sampling times (for example, n ≥ 30) can be achieved within a sine wave signal cycle, thereby reducing the sine wave signal fitting variance and improving the positioning accuracy of the positioning system. For example, the magnetic sensor sampling frequency is 1kHz, the number of sampling points n = 30, then the sine wave frequency f k No more than 33Hz.

[0102] In actual application scenarios, the sine wave frequency can be set to 24Hz, so that the full-load positioning frame rate of the positioning system can reach 24fps. By controlling the power-on state of the magnetic source coil and only powering the coil in part of the cycle, the system power consumption can be reduced (at the same time, the system positioning frame rate is reduced accordingly). It is easy to reduce the system positioning frame rate to a divisor of 24, and realize integer frame rate positioning such as 24, 12, 8, 6, 4, 3, 2, 1fps, etc., so as to achieve accurate matching of the positioning frame rate of the capsule endoscope with the real-time reading image frame rate.

[0103] In step S2, the magnetic field data information of the positioning target in the sinusoidal magnetic field is obtained, and the magnetic field data information includes the three-dimensional magnetic field component sensed by the positioning target in the sinusoidal magnetic field. The three-dimensional magnetic field component sensed by the positioning target is the superposition magnetic field of the three-dimensional sinusoidal magnetic field and the ambient magnetic field respectively excited by the three groups of magnetic source micro-electromagnetic coils when the three groups of magnetic source micro-electromagnetic coils are respectively energized.

[0104] In one embodiment of the present invention, Figure 2 As shown, fitting the three-dimensional magnetic field component of each dimension in step S3 specifically includes:

[0105] The magnetic field strength B in the corresponding dimension is obtained by performing function fitting on the magnetic field measurement values ​​of the dispersed three-dimensional magnetic field components. k；s (t);

[0106] The decomposition to obtain independent magnetic field signals of three groups of magnetic source micro-electromagnetic coils at the positioning target includes:

[0107] The magnetic field strength B after decomposition fitting k；s (t), obtain the magnetic induction intensity amplitude A of the independent magnetic field signals of the three groups of magnetic source micro electromagnetic coils at the positioning target k；s , the decomposition formula is:

[0108] B k；s (t) = A k；s sin(wt+b)+c k；s ;

[0109] Wherein, k represents the serial number of the magnetic source micro-electromagnetic coil, k=1, 2, 3; s=1, 2, 3, represents the three dimensions of the sinusoidal magnetic field, representing the X direction, the Y direction, and the Z direction respectively; A k；sis the magnetic induction intensity amplitude of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target to be decomposed and determined, that is, the magnetic field measurement peak value; c k；s is the background magnetic field component when each group of magnetic source micro-electromagnetic coils is energized respectively; the signal angular frequency w and the signal phase b are known quantities directly obtained according to the frequency value and phase value of the current data.

[0110] For the magnetic source of three sets of coils, the peak value of magnetic induction intensity A measured by the three-axis magnetic sensor k；s is a 3x3 matrix.

[0111] In one embodiment of the present invention, the decomposition formula may also be linearized to obtain a linearized decomposition formula:

[0112]

[0113] Among them, β 0；k；s X 0；k；s Characterizes the environmental magnetic field strength at the positioning target when the three groups of magnetic source micro electromagnetic coils are powered on respectively; β 1；k；s X 1 Characterize the three-dimensional magnetic field strength of the magnetic field signal at the positioning target when the three groups of magnetic source micro-electromagnetic coils are powered on respectively, that is, the three-dimensional magnetic field strength of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target;

[0114] Using a series of data at time t, {X j；k；s (t),B j；k；s (t)}, and solve the coefficient β through linear optimization j；k；s After that, it is easy to calculate the required magnetic induction intensity amplitude A k；s and background magnetic field c k；s This fitting process is performed independently for each of the 3x3=9 combinations of k and s, and the resulting magnetic induction intensity amplitude A k；s It is in the form of a 3x3 matrix.

[0115] The phase of the sinusoidal current of the coil is synchronized with the generated sinusoidal magnetic field. The phase information of the sinusoidal magnetic field measurement value can be directly obtained based on the known current phase (usually b=0 is set at the hardware level), reducing the algorithm complexity.

[0116] The magnetic field data measured by the magnetic sensor has the characteristics of periodic segmentation when the energized coil is switched. For example, the typical data characteristics are shown in Figure 3The magnetic field [Bx, By, Bz] measured by the three-axis magnetic sensor is divided into 3 groups by the coil identifier k, totaling 3x3=9 independent magnetic field components. The magnetic sensor measurement value conforms to the sine wave characteristics. When fitting according to the standard sine wave with phase b=0, the magnetic field amplitude can be negative, corresponding to the opposite direction of the positive direction of the magnetic sensor and the magnetic field.

[0117] like Figure 4 As shown in the figure, the characteristics of the magnetic field components are shown. For MEMS type micro magnetic sensors, the sampling frequency is limited, and the signal noise affects the accuracy of direct measurement. The amplitudes of the 3x3 groups of magnetic field signal data measured are orders of magnitude different. The small amplitudes of some components lead to a low signal-to-noise ratio, resulting in a large variance in the positioning results and low positioning accuracy. In addition, interference signals of other frequencies will also affect the accuracy of the direct measurement results. After fitting the n-point data, the standard deviation of the equivalent magnetic field measurement value can be reduced to the direct measurement result. The signal-to-noise ratio is significantly improved. Therefore, function fitting for magnetic field measurements is very valuable.

[0118] Function fitting can effectively suppress high-frequency noise and eliminate low-frequency background interference. Therefore, for positioning application scenarios with strict low-power requirements, using sinusoidal power supply to generate magnetic source magnetic field and using function fitting method to suppress high-frequency noise signals and separate low-frequency background signals at one time, and extracting high-accuracy coil magnetic field signal data is crucial to improving the accuracy of the positioning system.

[0119] Furthermore, the sinusoidal current of the coil is synchronized with the generated sinusoidal magnetic field. The phase and frequency of the corresponding independent magnetic field signal after separation can be directly obtained based on the known current phase and frequency. That is, the phase and frequency of the independent magnetic field signal are preset known quantities, and the magnetic induction intensity amplitude A of the independent magnetic field signal needs to be solved. k；s In the present invention, the superimposed magnetic field signal data B is decomposed according to the preset frequency s (t), other unimportant signals are thrown to c s (i.e. background magnetic field) item, including low-frequency and high-frequency signals (that is, signals that do not belong to the frequency of independent magnetic field signals).

[0120] The three groups of coils are energized alternately in a cycle, and the three-axis magnetic sensor obtains the time series data of the magnetic field measurement value at the spatial position, including the three-dimensional components of the magnetic field [Bx, By, Bz], as well as the identifier of the kth coil currently energized and the real-time current Ik. Ik can be used to online correct the resistance and current change drift caused by the temperature change of the coil and the actual magnetic field strength generated. The initial hardware parameter current peak value of Ik under ideal working conditions is Ik0, and the current peak value under actual working conditions (the peak value can be obtained by fitting the current series data Ik through a fitting method similar to step S3, or directly obtained through hardware) is Ik1, then the peak value of the magnetic induction intensity under actual working conditions needs to be corrected to Among them A 0；k；s is the magnetic field strength B after decomposition and fitting based on the phase information and angular frequency of the independent magnetic field signal k；s (t) The magnetic induction intensity amplitude A obtained k；s , A 1；k；s For the A 0；k；s The magnetic induction intensity amplitude is obtained after correcting the resistance and current change drift caused by the coil temperature change and the actual magnetic field intensity.

[0121] For low-power micro-electromagnetic portable positioning systems, after being worn for a certain period of time, the actual coil temperature tends to be stable human body temperature, with small changes, and the drift caused by temperature is also relatively small. However, setting the ideal operating temperature to about 37°C for Ik0 calibration can omit the above temperature-induced magnetic field theoretical value correction.

[0122] The timing control logic of the cyclic alternating power supply is shown in Figure 5-7 , the three groups of coils switch power supply in sequence for a complete cycle, and only one group of coils is powered in each cycle, which can avoid the 3 times power consumption problem required for the three groups of coils to be powered at the same time. Compared with the simultaneous power supply solution, under the same power consumption, the coil current and magnetic field strength signal-to-noise ratio can be increased by about 1.732 times, thereby improving the positioning performance indicators of the system.

[0123] The switching interval time dt of each coil power supply can be 0( Figure 5 ), or a smaller interval other than 0 ( Figure 6 , Figure 7 ), reducing the interference of magnetic fields between coils. For three sets of coils arranged orthogonally to each other, this interference is very small, and switching near the current phase b = 0 can further minimize the interference amplitude. Therefore, the power supply switching time interval dt = 0 can be set to increase the magnetic field refresh frequency, thereby increasing the frame rate of the positioning system.

[0124] When the positioning system reduces the positioning frame rate, all coils are in a no-load state during some periodic periods, which can further reduce the power consumption of the system. There are two ways to reduce the positioning frame rate: long interval mode and short interval mode. The power control timing logic diagram of the long interval mode is shown in Figure 6 After the three sets of coils are energized alternately once, they are kept in an unloaded state for a long interval, and then energized alternately again. See the timing logic diagram of the short interval energization control. Figure 7 , the three groups of coils are energized alternately at shorter and more uniform intervals. The short interval method is more conducive to data stability when the magnetic field measurement data is reused, and the stability of the positioning solution results is better. Both methods can achieve the purpose of reducing the positioning frame rate and reducing the power consumption of the coil. For example, the situation shown in the figure can further reduce the power consumption of the magnetic source coil to 1 / 3 of the full load, thereby improving the endurance of the positioning system. At the same time, the positioning frame rate is reduced from 24fps to 8fps. According to a similar method, positioning with lower power consumption and lower frame rate can be achieved, and the real-time performance of positioning is also reduced.

[0125] Correspondingly, the positioning unit can also synchronously adopt a frequency reduction mechanism to detect and collect magnetic field signals, thereby saving the communication timing and energy consumption of the capsule endoscope.

[0126] In one embodiment of the present invention, the peak value of magnetic induction intensity A k；s The matrix is ​​updated using a cyclic refresh mechanism, with 1x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the same set of coils is energized. The three sets of coils are energized alternately, and the above matrix elements are also updated cyclically. When the positioning frame rate is high and the movement of the positioning target is relatively stable, it can be approximately considered that the 3x3 matrix elements are measured simultaneously. Small disturbances of the positioning target can be suppressed by filtering the positioning results. The filtering algorithm can use mean smoothing filtering, Kalman filtering, etc., all of which can achieve good results.

[0127] The cyclic refresh mechanism of the peak value of magnetic induction intensity can perform a positioning solution every time it is updated, without waiting for the entire 3x3 matrix to be fully refreshed. It can avoid energizing the three sets of coils at the same time, significantly saving the power consumption of the magnetic source coil system. At the same time, it maintains the effect of approximately equivalent magnetic field generation and detection, and does not affect the real-time positioning and does not reduce the positioning frame rate.

[0128] In one embodiment of the present invention, a positioning cycle of the micro-electromagnetic positioning method is T=T 1 +d t , where T 1 is the power supply time of each group of the three magnetic source micro electromagnetic coils, d t The switching interval time for supplying power to each group of the three groups of magnetic source micro electromagnetic coils.

[0129] Enter the mth positioning cycle, m≥3, the time of the mth positioning cycle T=T 1 +d t , where T 1 is the power supply time of each group of the three magnetic source micro electromagnetic coils, d t a switching interval for supplying power to each of the three groups of magnetic source micro-electromagnetic coils;

[0130] The method of using a fixed frequency sinusoidal current to cyclically and alternately pass through three groups of magnetic source micro-electromagnetic coils in sequence to excite a three-dimensional sinusoidal magnetic field includes:

[0131] The first group of magnetic source micro-electromagnetic coils is powered in the m-3th positioning period, the second group of magnetic source micro-electromagnetic coils is powered in the m-2th positioning period, the third group of magnetic source micro-electromagnetic coils is powered in the m-1th positioning period, the first group of magnetic source micro-electromagnetic coils is powered in the m-3+3nth positioning period, the second group of magnetic source micro-electromagnetic coils is powered in the m-2+3nth positioning period, and the third group of magnetic source micro-electromagnetic coils is powered in the m-1+3nth positioning period, where n≥1.

[0132] The peak value of magnetic induction intensity A k；s The matrix adopts a cyclic refresh mechanism to update, specifically including: in the current m-3+3n positioning cycle, the magnetic induction intensity peak value A k；s Including the peak value A of the magnetic induction intensity obtained when the first group of magnetic source micro-electromagnetic coils are powered during the m-3+3n positioning cycle 1；s , the peak value of magnetic induction intensity A obtained when the second group of magnetic source micro-electromagnetic coils are powered during the m-5+3n positioning cycle 2；s , the peak value of magnetic induction intensity A obtained when the third group of magnetic source micro-electromagnetic coils are powered in the m-4+3n positioning cycle 3；s , that is, in the current m-3+3n positioning cycle, the peak value of the magnetic induction intensity A k；s The peak value of magnetic induction intensity A obtained when the first group of magnetic source micro-electromagnetic coils are powered during the m-6+3n positioning cycle in the matrix 1；s Updated to the peak value of magnetic induction intensity A obtained when the first group of magnetic source micro-electromagnetic coils are powered in the m-3+3nth positioning cycle 1；s Similarly, in the current m-2+3nth positioning cycle, the peak value of the magnetic induction intensity A k；s Including the peak value A of the magnetic induction intensity obtained when the first group of magnetic source micro-electromagnetic coils are powered during the m-3+3n positioning cycle 1；s , the peak value of magnetic induction intensity A obtained when the second group of magnetic source micro-electromagnetic coils are powered during the m-2+3n positioning cycle 2；s , the peak value of magnetic induction intensity A obtained when the third group of magnetic source micro-electromagnetic coils are powered in the m-4+3n positioning cycle 3；s, that is, in the current m-2+3nth positioning cycle, the peak value of the magnetic induction intensity A k；s The peak value of magnetic induction intensity A obtained when the second group of magnetic source micro-electromagnetic coils are powered during the m-5+3n positioning cycle in the matrix 2；s Updated to the peak value of magnetic induction intensity A obtained when the second group of magnetic source micro-electromagnetic coils are powered in the m-2+3nth positioning cycle 2；s .

[0133] In one embodiment of the present invention, the peak value of magnetic induction intensity A k；s The matrix is ​​updated using a cyclic refresh mechanism, with 3x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the three sets of coils are energized. The three sets of coils are energized alternately, and the above matrix elements are also updated cyclically. In this case, in each positioning cycle, the three sets of coils are energized alternately once, and a 3x3 peak value of magnetic induction intensity A is obtained. k；s matrix.

[0134] See Figure 6 As shown in the long interval mode power-on control timing logic diagram, after the three sets of coils are alternately energized once, they are kept in a no-load state for a long interval, and then alternately energized once again. Since a long interval of no-load state is maintained between each positioning cycle, the 3x3 matrix elements obtained in adjacent positioning cycles cannot be considered to be measured simultaneously. Therefore, in this implementation, 3x3 matrix elements are updated in each positioning cycle to ensure the real-time positioning under low frame rate conditions and obtain better positioning effects.

[0135] In one embodiment of the present invention, step S4 of obtaining the position and attitude information of the positioning target according to the independent magnetic field signal specifically includes:

[0136] Three sets of orthogonal coils can obtain 3x3=9 independent magnetic induction intensity amplitudes A k；s , which is sufficient to calculate the 6DOF position and attitude information of the magnetic sensor at its spatial position.

[0137] When the size of the magnetic source coil is small, the spatial distribution of the magnetic induction intensity can be simplified by using the magnetic dipole approximation. The calculation formula for the peak value of the magnetic induction intensity is:

[0138]

[0139] Among them, μ 0 is the vacuum magnetic permeability; M k is the peak value of the equivalent magnetic moment after the kth coil is energized, is the unit vector of the equivalent magnetic moment of the kth coil, k = 1, 2, 3; is the spatial position vector; is the spatial position unit vector;

[0140] According to the peak value of magnetic induction intensity Obtain the theoretical value of the magnetic induction intensity peak matrix Specifically, the peak magnetic induction intensity It can be expressed as a matrix component form Where k is the magnetic source coil number, and s is the three-dimensional component measured by the three-axis magnetic sensor. For the magnetic source of the three sets of coils, is a 3x3 matrix. It should be noted that the magnetic induction intensity Equivalent to the theoretical value of the magnetic induction intensity peak matrix

[0141] The position and attitude information of the positioning target is obtained by solving the corresponding relationship between the theoretical value of the magnetic induction intensity peak matrix and the magnetic field measurement peak in the independent magnetic field signal through a nonlinear optimization algorithm; wherein the corresponding relationship is:

[0142]

[0143] in, A is the sensor attitude rotation matrix; k；s Measure the peak value of the magnetic field; is the theoretical value of the magnetic induction intensity peak matrix;

[0144] The sensor attitude rotation matrix can be uniquely determined by rotating the Euler angles yaw, pitch, and roll (the order of Euler angle rotation only needs to be consistent in the formula system, there is no special order requirement, and the ZYX order can generally be selected according to convention).

[0145] The following parameter optimization problem is solved by nonlinear optimization algorithm (such as LM algorithm, etc.):

[0146]

[0147] In the nonlinear optimization algorithm, the position information X, Y, Z and 3DOF attitude angles yaw (yaw angle), pitch (pitch angle) and roll (roll angle) of the positioning target are calculated based on the known theoretical value of the magnetic induction intensity peak matrix and the known magnetic field measurement peak value.

[0148] In one embodiment of the present invention, it also includes: obtaining the pitch angle pitch and roll angle roll of the positioning target, and calculating the yaw angle yaw and the position coordinates of the positioning target according to the pitch angle pitch, roll angle roll of the positioning target and the independent magnetic field signal.

[0149] Specifically, the pitch angle and roll angle of the capsule endoscope (positioning target) can be directly obtained with higher accuracy through additional devices such as IMU (inertial measurement unit). The pitch angle and roll angle are used as known input parameters. This can reduce the number of unknown parameters (from 6 to 4), further simplify the above nonlinear solution, and improve the efficiency of positioning solution.

[0150] It is further explained that, since the orthogonal magnetic source coil has the geometric feature of central symmetry, the magnetic field distribution of the magnetic source has central symmetry about the origin, and the above positioning results cannot distinguish the 3DOF position points (+x, +y, +z) and (-x, -y, -z) that are centrally symmetric about the origin. The central symmetry can be eliminated by limiting the positioning area to a half-space (for example, Y>0 or Z>0, etc.), so that the positioning solution result is uniquely determined. For example, when the positioning area is limited to a half-space Z>0, if z<0 in the solution result (x, y, z), the position result can be remapped to (-x, -y, -z).

[0151] Through the above positioning solution method, target positioning based on the micro-electromagnetic positioning method can be achieved.

[0152] It should be noted that in the capsule endoscope application scenario, the positioning target includes the capsule endoscope, but in other embodiments, it not only includes the capsule endoscope, for example, includes the auxiliary positioning reference point.

[0153] The relative position and posture of the magnetic source relative to the capsule caused by the changes in the posture of the human body and the fluctuation of the abdomen during breathing may cause the capsule positioning results to be misplaced or fluctuate ( Fig.12 ), which affects the positioning of the capsule in the intestine and the reconstruction of the trajectory, causing the positioning tail to be blurred. In order to further enhance the stability of the positioning system, additional auxiliary positioning reference points are used to perform online calibration of the positioning results.

[0154] The principle of online calibration of positioning results is based on the change of fixed reference point represented by three-dimensional scaling transformation S and three-dimensional rotation change W around the origin. x ,s y ,s z ), which represents the three-dimensional expansion and contraction of the human abdomen in the three spatial directions of X, Y, and Z, caused by the displacement of flexible organs in the body and the rise and fall of the abdomen due to the change in lung volume during breathing; W can be uniquely represented by three rotational Euler angles, which approximately represents the influence of posture changes such as twisting and tilting of the human trunk. There are a total of 6 parameters to be determined, and at least N (N≥2) positioning reference points are required to determine the spatial distortion characteristics of this positioning.

[0155] like Figure 10-12As shown, in one embodiment of the present invention, the positioning target includes at least one main positioning target 3 and N (N≥2) auxiliary positioning targets 103, 104, 105, 106... (i.e., auxiliary positioning reference points), and the micro-electromagnetic positioning method also includes a positioning calibration method, and the specific steps include:

[0156] S4.1: Calculate the position information of N (N≥2) auxiliary positioning targets 103, 104, 105, 106, ... for multiple times within a preset time period and calculate the average position of the N (N≥2) auxiliary positioning targets;

[0157] S4.2: Calculate the position information of the main positioning target 3 and the position information of the N (N≥2) auxiliary positioning targets 103, 104, 105, 106, ... after a preset time period;

[0158] S4.3: Construct a scaling and rotational change matrix W*S to calibrate the position information of the main positioning target 3 within the target detection area.

[0159] The center of the magnetic source is taken as the coordinate origin O (in actual situations, because breathing causes the internal organs to squeeze and the abdomen to rise and fall, the magnetic source center fluctuates, and other positioning points move relative to O). At time T1, the capsule positioning point C1, and the N positioning reference points are (In actual use, only some reference points may be enabled, for example, D11 and D21); at time T2, capsule positioning point C2, the N positioning reference points are

[0160] Under the statistical average state of abdominal respiratory fluctuations, the relative positions of OD1, OD2, OD3, OD4...ODN are approximately constant. By changing the relative positions of OD1, OD2, OD3, OD4...ODN, the relative position of OC can be corrected in real time, significantly reducing the influence of the large fluctuations in the positioning result of capsule C caused by the fluctuations of the human abdomen.

[0161] Preferably, in the step S4.1, the position information of N (N≥2) auxiliary positioning targets 103, 104, 105, 106, ... is calculated multiple times within a preset time period and is obtained when the human body is in an upright standard posture.

[0162] Preferably, the preset duration is 1 minute.

[0163] Specifically, when the human body is in an upright standard posture, the average position of the positioning reference points D1, D2, D3, D4, ..., DN over a period of time (e.g., 1 minute) is counted as the standard position of the positioning result. At the next moment T2, the capsule positioning point C2 and the N positioning reference points are

[0164] The construction of the scaling and rotational change matrix W*S in step S4.3 satisfies Solve the transformation matrix by pseudo-inverse operation

[0165] in, The D N1 The position information of N (N≥2) auxiliary positioning targets obtained by multiple calculations within the preset time length, The set matrix of average positions of N (N≥2) auxiliary positioning targets is obtained by calculating the position information of N (N≥2) auxiliary positioning targets for multiple times within the preset time length; The D N2 is the location information of N (N≥2) auxiliary positioning targets calculated after the preset time period, is a collection matrix of position information of N (N≥2) auxiliary positioning targets calculated after the preset time length;

[0166] The calibrating the position information of the main positioning target in the target detection area specifically includes calibrating the position information C2 of the main positioning target calculated after the preset time length to obtain new position information C, satisfying C=W·S·C 2 .

[0167] The above positioning point set P is a 3xN matrix (each positioning reference point is a 3x1 vector, and N reference points constitute a 3xN matrix), and W and S are 3x3 matrices. Therefore, the instant positioning result C2 of the capsule can be calibrated as C=W·S·C 2 .

[0168] Preferably, the number of auxiliary positioning reference points N = 2, 3, 4. Using 2-4 positioning reference points (see Figure 11-12 ), plus a magnetic source center point as the coordinate origin O, can achieve a better correction effect of the positioning result. A large number of positioning reference points can reduce interference and provide better correction effects, but it will increase the hardware communication overhead and positioning solution overhead. In general, it is a reasonable choice to use no more than 4 positioning reference points. In actual use, you can choose to enable only some (no less than 2).

[0169] Through the above calibration method, the distortion of capsule positioning results caused by changes in the internal organs and external torso of the human body can be eliminated, and a more stable correction positioning result can be obtained.

[0170] like Fig.10 and Fig.11As shown, in one embodiment of the present invention, a micro-electromagnetic positioning system is also provided, which can excite and generate a sinusoidal magnetic field, and the positioning target can obtain a three-dimensional magnetic field component in the sinusoidal magnetic field to facilitate positioning and solving to obtain the position and posture information of the positioning target. Specifically including:

[0171] The magnetic field generating assembly 102 includes three groups of magnetic source micro electromagnetic coils arranged on the excitation magnetic core, the magnetic source micro electromagnetic coils are used to receive sinusoidal current and generate three-dimensional sinusoidal magnetic fields. The three groups of magnetic source micro electromagnetic coils are orthogonal to each other and their centers coincide with the center of the excitation magnetic core.

[0172] The positioning target includes a three-dimensional magnetic sensor for receiving the sinusoidal magnetic field and sensing three-dimensional magnetic field components.

[0173] The positioning processing component 201 is electrically connected to the magnetic field generating component 102. The current generated by the positioning processing component 201 excites the magnetic source micro-electromagnetic coil to generate a three-dimensional sinusoidal magnetic field.

[0174] The positioning processing component 201 is configured to implement the micro-electromagnetic positioning method as described in any of the above embodiments. The micro-electromagnetic positioning method can calculate the position and posture of the positioning target in the target detection area. The micro-electromagnetic positioning method can also calibrate the position of the positioning target in the target detection area. The micro-electromagnetic positioning method is not described in detail here.

[0175] The magnetic field generating component 102 is used as a sinusoidal magnetic field generating source, and in the positioning process, it is usually used as the coordinate circle center O. The three-dimensional magnetic sensor can be a chip-type high-precision, low-noise magnetic sensor suitable for weak magnetic field environments such as AK09940, MMC5983MA, and MMC5603NJ; it is used to measure the three-dimensional magnetic field components at a spatial position.

[0176] The positioning processing component 201 can be connected to the magnetic field generating component 102 and the positioning target for communication so as to control the operation of the magnetic field generating component 102 and the positioning target. On the one hand, it controls the magnetic field generating component 102 to generate a sinusoidal magnetic field. On the other hand, it controls the three-dimensional magnetic sensor in the positioning target to sense the sinusoidal magnetic field to generate a three-dimensional magnetic field component. Finally, the positioning processing component 201 performs positioning solution to obtain the position information.

[0177] In one embodiment, if Figure 10-11As shown, the micro-electromagnetic positioning system also includes a waist belt 101, a fixed belt 202 and a connecting cable bundle 203. The positioning target includes at least a main positioning target 3 and N auxiliary positioning targets 103, 104, 105, 106... The N auxiliary positioning targets 103, 104, 105, 106... are arranged on the waist belt 101 at intervals with the magnetic field generating component 102 to form a target detection area. The positioning processing component 201 is installed on the fixed belt 202. The positioning processing component 201 is electrically connected to the magnetic field generating component 102 through the connecting cable bundle 203, and excites the magnetic field generating component 102 to generate a three-dimensional sinusoidal wave magnetic field. The main positioning target 3 is located in the target detection area.

[0178] In one embodiment, the fixing strap 202 can be represented as a leg strap, and the positioning processing component 201 is arranged on the leg strap, and is separated from the magnetic field generating component 102 and N auxiliary positioning targets 103, 104, 105, 106... on the waist belt 101, thereby forming a lightweight positioning system, and can also reduce the weight of the waist belt 101, thereby reducing interference with the positioning processing component 102.

[0179] In other embodiments, the fixing strap 202 may be represented as a strap fixed to other places, such as a wrist strap or other devices fixed to the outside of the human body.

[0180] In this way, the belt form is more lightweight, and also greatly reduces the size of the device and reduces power consumption.

[0181] The magnetic field generating component 102 generates a three-dimensional pulse magnetic field to detect the main positioning target 3, and obtains the position and posture information of the main positioning target 3. Based on the auxiliary positioning of N auxiliary positioning targets 103, 104, 105, 106..., the position of the main positioning target 3 can be further accurately obtained.

[0182] like Fig.13 As shown, the positioning processing component 201 includes a sinusoidal pulse width modulation module 2011, which is electrically connected to each group of coils and is configured to excite the corresponding coils to generate a sinusoidal magnetic field according to three different preset magnetic field frequencies.

[0183] The positioning processing component 201 can independently provide load-carrying sinusoidal alternating current of specific frequency and amplitude to the three groups of coils through steps such as DC boosting and modulation by the sinusoidal pulse width modulation module 2011.

[0184] The system uses a DC power supply (a high-energy-density rechargeable lithium battery, such as 18650, 21700 lithium battery or lithium-ion polymer battery) to ensure overall portability. The DC power is converted into a standard sinusoidal AC power of a specific amplitude (within the safe voltage range), frequency, and phase, which is used to power the electromagnetic coil to generate a sinusoidal magnetic field. Under the same signal peak, the power consumption of the sinusoidal signal is only 1 / 2 of that of the square wave pulse signal, which can effectively reduce the power consumption of the micro-electromagnetic positioning method and increase the endurance of continuous positioning. The sinusoidal electrical signal has no mutations, and will not cause distortion of the sinusoidal magnetic field and high-frequency harmonic interference to the inductive coil, which can achieve better positioning stability and accuracy.

[0185] In one embodiment of the present invention, the positioning target may further include an inertial measurement unit for acquiring inertial measurement data, assisting positioning calculation, and improving the efficiency of positioning solution.

[0186] In one embodiment of the present invention, the positioning target may further include a main control module for obtaining three-dimensional magnetic field components and inertial measurement data and transmitting them to the positioning processing component 201 .

[0187] like Fig.14 As shown, in one embodiment of the present invention, the main positioning target 3 includes a first three-dimensional magnetic sensor 31, a first inertial measurement unit 32 and a first main control module 33, the first auxiliary positioning target 103 includes a second three-dimensional magnetic sensor 1031, a second inertial measurement unit 1032 and a second main control module 1033, the second auxiliary positioning target 104 includes a third three-dimensional magnetic sensor 1041, a third inertial measurement unit 1042 and a third main control module 1043, the third auxiliary positioning target 105 includes a fourth three-dimensional magnetic sensor 1051, a fourth inertial measurement unit 1052 and a fourth main control module 1053, the fourth auxiliary positioning target 106 includes a fifth three-dimensional magnetic sensor 1061, a fifth inertial measurement unit 1062 and a fifth main control module 1063, the Nth auxiliary positioning target includes...

[0188] Correspondingly, the positioning processing component 201 includes a positioning unit 2012, and the positioning unit 2012 can receive the feedback three-dimensional magnetic field component, and perform positioning calculation according to the three-dimensional magnetic field component to obtain position and posture information.

[0189] like Fig.14 As shown, in one embodiment of the present invention, the main positioning target 3 also includes an imaging unit 34, and the imaging unit 34 is used to capture images; the imaging unit 34 is not limited to one group, and can include multiple groups, for example: two groups of imaging units 34 distributed at both ends of the capsule can capture images in the digestive tract simultaneously, alternately or independently.

[0190] In one embodiment of the present invention, a storage medium is provided, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the micro-electromagnetic positioning method in the above embodiment are implemented.

[0191] It should be noted that the storage medium shown may be a removable storage medium 611 .

[0192] Fig.15 The structure block diagram of a computer system for implementing the storage medium of an embodiment of the present application is schematically shown.

[0193] It should be noted that Fig.15 The computer system 6 of the storage medium shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0194] like Fig.15 As shown, the computer system 6 includes a central processing unit 601 (CPU), which can perform various appropriate actions and processes according to the program stored in the read-only memory 602 (ROM) or the program loaded from the storage part 608 to the random access memory 603 (RAM). Various programs and data required for system operation are also stored in the random access memory 603. The central processing unit 601, the read-only memory 602 and the random access memory 603 are connected to each other through a bus 604. An input / output interface 605 (Input / Output interface, i.e., I / O interface) is also connected to the bus 604.

[0195] The following components are connected to the input / output interface 605: an input section 606 including a keyboard, a mouse, etc.; an output section 607 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a local area network card, a modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the input / output interface 605 as needed. A removable medium 611, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 610 as needed so that a computer program read therefrom is installed into the storage section 608 as needed.

[0196] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, systems and modules can refer to the corresponding processes in the aforementioned method implementation methods and will not be repeated here.

[0197] In several embodiments provided in the present application, it should be understood that the disclosed systems, systems and methods can be implemented in other ways. For example, the system implementation described above is only schematic, for example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, systems or modules, which can be electrical, mechanical or other forms. The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the present implementation scheme.

[0198] In addition, each functional module in each embodiment of the present application can be integrated into a processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The above-mentioned integrated module can be implemented in the form of hardware or in the form of hardware plus software functional modules. The above-mentioned integrated module implemented in the form of software functional modules can be stored in a computer-readable storage medium. The above-mentioned software functional modules are stored in a storage medium, including a number of instructions for a computer system (which can be a personal computer, a server, or a network system, etc.) or a processor (processor) to perform some steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk.

[0199] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned implementation modes, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned implementation modes, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various implementation modes of the present application.

Claims

1. A micro-electromagnetic positioning method, characterized in that: include: A sinusoidal current of a fixed frequency is used to circulate alternately through three groups of magnetic source micro-electromagnetic coils in sequence to excite a three-dimensional sinusoidal magnetic field. The magnetic field data information of the positioning target in the sinusoidal magnetic field is obtained, and the magnetic field data information of the positioning target in the corresponding sinusoidal magnetic field is obtained based on each time a group of the magnetic source micro-electromagnetic coils are energized, wherein the magnetic field data information includes the three-dimensional magnetic field components sensed by the positioning target in the sinusoidal magnetic field. The three-dimensional magnetic field component of each dimension is fitted, and decomposed to obtain independent magnetic field signals of three groups of magnetic source micro-electromagnetic coils at the positioning target. The position and posture information of the positioning target are obtained according to the independent magnetic field signal.

2. The micro-electromagnetic positioning method according to claim 1, characterized in that: The frequency of the sinusoidal current is fixed to satisfy f ps ≤f≤f s / n, where f ps is the full-load positioning frame rate of the positioning system, f s is the sampling frequency of the magnetic sensor, and n is the number of samples that can be achieved within one cycle of a sinusoidal wave signal.

3. The micro-electromagnetic positioning method according to claim 1, characterized in that: The fitting of the three-dimensional magnetic field component of each dimension specifically includes: performing function fitting on the magnetic field measurement values ​​of the dispersed three-dimensional magnetic field components to obtain the magnetic field intensity B in the corresponding dimension k；s (t); The decomposition to obtain the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target includes: the magnetic field strength B after decomposition and fitting k；s (t), obtain the magnetic induction intensity amplitude A of the independent magnetic field signals of the three groups of magnetic source micro electromagnetic coils at the positioning target k；s , the decomposition formula is: B k；s (t)=A k；s sin(wt+b)+c k；s ; Wherein, k represents the serial number of the magnetic source micro-electromagnetic coil, k=1, 2, 3; s=1, 2, 3, represents the three dimensions of the sinusoidal magnetic field, representing the X direction, the Y direction, and the Z direction respectively; A k；s is the magnetic induction intensity amplitude of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target to be determined and decomposed, that is, the magnetic field measurement peak value; c k；s is the background magnetic field component when each group of magnetic source micro-electromagnetic coils is energized respectively; the signal angular frequency w and the signal phase b are known quantities directly obtained according to the frequency value and phase value of the current data.

4. The micro-electromagnetic positioning method according to claim 3, characterized in that: The decomposition formula is linearized to obtain the linearized decomposition formula: Among them, β 0；k；s X 0；k；s Characterizes the environmental magnetic field intensity at the positioning target when the three groups of magnetic source micro electromagnetic coils are powered on respectively; β 1；k；s X1 represents the three-dimensional magnetic field strength of the magnetic field signal at the positioning target when the three groups of magnetic source micro-electromagnetic coils are powered on respectively, that is, the three-dimensional magnetic field strength of the independent magnetic field signals of the three groups of magnetic source micro-electromagnetic coils at the positioning target; Using a series of data at time t, {X j；k；s (t),B j；k；s (t)}, and solve the coefficient β through linear optimization j；k；s After that, it is easy to calculate the required magnetic induction intensity amplitude A k；s and background magnetic field c k；s .

5. The micro-electromagnetic positioning method according to claim 4, characterized in that: The magnetic induction intensity amplitude A k；s Correction is performed, and the correction formula is Where Ik0 is the initial hardware parameter current peak value under ideal working conditions, Ik1 is the current peak value under actual working conditions, A 0；k；s is the magnetic field strength B after decomposition fitting k；s (t) The magnetic induction intensity amplitude A obtained k；s , A 1；k；s For the A 0；k；s The magnetic induction intensity amplitude is obtained after correcting the resistance and current change drift caused by the coil temperature change and the actual magnetic field intensity.

6. The micro-electromagnetic positioning method according to claim 5, characterized in that: The magnetic induction intensity amplitude A k；s The matrix is ​​updated using a cyclic refresh mechanism, with 1x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the same set of coils is energized.

7. The micro-electromagnetic positioning method according to claim 5, characterized in that: The magnetic induction intensity amplitude A k；s The matrix is ​​updated using a cyclic refresh mechanism, with 3x3 matrix elements updated each time, corresponding to the magnetic field generated at the magnetic sensor when the three sets of coils are energized.

8. The micro-electromagnetic positioning method according to claim 5, 6 or 7, characterized in that: Acquiring the position and attitude information of the positioning target according to the independent magnetic field signal specifically includes: The spatial distribution of magnetic induction intensity is simplified by using the magnetic dipole approximation. The calculation formula for the peak value of magnetic induction intensity is: Where μ0 is the vacuum magnetic permeability; M k is the peak value of the equivalent magnetic moment after the kth coil is energized, is the unit vector of the equivalent magnetic moment of the kth coil, k = 1, 2, 3; is the spatial position vector; is the spatial position unit vector; According to the peak value of magnetic induction intensity Obtain the theoretical value of the magnetic induction intensity peak matrix The position and attitude information of the positioning target is obtained by solving the corresponding relationship between the theoretical value of the magnetic induction intensity peak matrix and the magnetic field measurement peak in the independent magnetic field signal through a nonlinear optimization algorithm; wherein the corresponding relationship is: in, A is the sensor attitude rotation matrix; k；s Measure the peak value of the magnetic field; is the theoretical value of the magnetic induction intensity peak matrix; The nonlinear optimization algorithm is:

9. The micro-electromagnetic positioning method according to claim 1, characterized in that: Also includes: The pitch angle pitch and the roll angle roll of the positioning target are obtained, and the yaw angle yaw and the position coordinates of the positioning target are calculated according to the pitch angle pitch, the roll angle roll of the positioning target and the independent magnetic field signal.

10. The micro-electromagnetic positioning method according to claim 1, characterized in that: The positioning target includes at least one main positioning target and N auxiliary positioning targets. The micro-electromagnetic positioning method also includes a positioning calibration method, and the specific steps include: Calculate the position information of N (N≥2) auxiliary positioning targets multiple times within a preset time length and calculate the average position of the N (N≥2) auxiliary positioning targets; Calculating the position information of the main positioning target and the position information of the N (N≥2) auxiliary positioning targets after a preset time period; Construct a scaling and rotation change matrix W*S to calibrate the position information of the main positioning target in the target detection area.

11. The micro-electromagnetic positioning method according to claim 10, characterized in that: The position information of N (N≥2) auxiliary positioning targets is calculated multiple times within a preset time period, and is obtained when the human body is in an upright standard posture. The preset time period is 1 minute.

12. The micro-electromagnetic positioning method according to claim 10, characterized in that: The construction of the scaling and rotation change matrix W*S satisfies Solve the transformation matrix by pseudo-inverse operation in, The D N1 The position information of N (N≥2) auxiliary positioning targets obtained by multiple calculations within the preset time length, The set matrix of average positions of N (N≥2) auxiliary positioning targets is obtained by calculating the position information of N (N≥2) auxiliary positioning targets for multiple times within the preset time length; The D N2 is the location information of N (N≥2) auxiliary positioning targets calculated after the preset time period, is a collection matrix of position information of N (N≥2) auxiliary positioning targets calculated after the preset time length; The calibrating the position information of the main positioning target in the target detection area specifically includes calibrating the position information C2 of the main positioning target calculated after a preset time period to obtain new position information C, satisfying C=W·S·C2.

13. The micro-electromagnetic positioning method according to claim 10, 11 or 12, characterized in that: The number of auxiliary positioning targets N=2, 3, 4.

14. A micro electromagnetic positioning system, characterized in that: include: A magnetic field generating component, comprising three groups of magnetic source micro-electromagnetic coils arranged on an excitation magnetic core, wherein the magnetic source micro-electromagnetic coils are used to receive a sinusoidal current and generate a three-dimensional sinusoidal magnetic field; A positioning target includes a three-dimensional magnetic sensor for receiving the sinusoidal magnetic field and sensing a three-dimensional magnetic field component; A positioning processing component, electrically connected to the magnetic field generating component and the positioning target; The positioning processing component is configured to implement the micro-electromagnetic positioning method as described in any one of claims 1-12.

15. The micro-electromagnetic positioning system according to claim 14, characterized in that: The three groups of magnetic source micro-electromagnetic coils are orthogonal to each other, and their centers coincide with the center of the excitation magnetic core.

16. The micro-electromagnetic positioning system according to claim 14, characterized in that: It also includes a waist belt, a fixing belt and a connecting cable bundle, the positioning target includes at least a main positioning target and N auxiliary positioning targets, the N auxiliary positioning targets are spaced apart from the magnetic field generating component on the waist belt to form a target detection area, the positioning processing component is installed on the fixing belt, the positioning processing component is electrically connected to the magnetic field generating component through the connecting cable bundle, and excites the magnetic field generating component to generate a three-dimensional sinusoidal wave magnetic field, and the main positioning target is located in the target detection area.

17. The micro-electromagnetic positioning system according to claim 16, characterized in that: The fixing strap is a leg strap, and the positioning processing component is installed on the leg strap.

18. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps in the micro electromagnetic positioning system as claimed in any one of claims 1 to 13 are implemented.

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