A method and system for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system

Abstract

The present invention discloses a method and system for calibrating the sensitivity of a receiving module in an electromagnetic positioning and tracking system, belonging to the field of wireless electromagnetic positioning technology. The calibration method includes: constructing a stable magnetic field calibration space with controllable frequency and intensity; placing a measured object in the calibration space, causing the measured object to sense the magnetic field signal in the calibration space through a receiving coil, and processing the magnetic field signal to obtain measured object data; calculating the sensitivity under different magnetic field intensities, and performing plotting and fitting to obtain the sensitivity parameters of the measured object. The present invention can accurately calibrate the sensitivity of the receiving module of the electromagnetic positioning and tracking system under different magnetic field intensities, and obtain the optimal calibration parameters through calibration curve fitting and correction, effectively improving the absolute positioning accuracy of the electromagnetic positioning and tracking system.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless electromagnetic positioning, and in particular to a method and system for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system. Background Art

[0002] Electromagnetic positioning and tracking technology is a technology that uses the principle of electromagnetic fields to monitor the real-time position and motion status of targets. Its core principle is to determine the spatial coordinates and trajectory of the target by transmitting and receiving electromagnetic signals and analyzing the propagation characteristics, phase changes or magnetic field strength differences of electromagnetic waves.

[0003] Electromagnetic positioning and tracking technology enables real-time tracking of a target's spatial position and posture within a meter-scale range, with millimeter to submillimeter accuracy. With its high precision, unobstructed operation, and anti-interference capabilities, it holds broad application prospects in complex environment positioning, AR / VR virtual interaction, surgical navigation, and minimally invasive interventions.

[0004] Compared to traditional optical tracking technology, electromagnetic tracking effectively avoids the drawback of target loss caused by optical obstruction. However, one drawback is the relatively complex structure of the electromagnetic tracking system, requiring an accurate and reliable calibration solution to compensate for system deviations and improve the system's absolute positioning accuracy. Therefore, how to accurately and effectively calibrate the received signals of the electromagnetic tracking system is key to improving the accuracy and reliability of the tracking system.

[0005] By searching relevant patents and academic papers on the calibration scheme of the electromagnetic positioning and tracking system receiving module,

[0006] Invention patent CN118962551B discloses a device and method for detecting the sensitivity of a receiving coil in an electromagnetic positioning scenario. The device can adapt to different magnetic field strengths and operating frequencies, improves the applicability of the device in detecting the sensitivity of the receiving coil, and ensures the accuracy and reliability of sensitivity detection.

[0007] In the academic paper "A DC Magnetostatic Positioning Model and Experimental Verification Based on a Magnetic Dipole," the authors used a three-axis orthogonal coil as the transmitter and a three-axis orthogonal magnetostatic sensor as the receiver. The receiver sensitivity calibration proposed in this paper involves a coil as the receiving sensor, which is fundamentally different from a magnetostatic sensor and does not represent the same electromagnetic positioning system solution.

[0008] In the academic paper "Six-Dimensional Posture Electromagnetic Positioning System Based on Embedded System", the system calibration involved in the electromagnetic positioning system described by the author includes coupling coefficient calibration, transmitting coil position and direction correction, which is mainly to solve the system positioning deviation introduced by the coupling of the coil axes and the orthogonality error in the winding process. It does not belong to the same category as the receiving end sensitivity calibration proposed in this invention. Sensitivity calibration is the quantitative relationship between the measurement signal at the receiving end and the standard magnetic field.

[0009] In summary, there are relatively few patents related to the calibration of the receiving sensitivity of electromagnetic positioning and tracking systems in the existing disclosed related patent technologies. The calibration devices and methods only target the receiving coil component and do not include the receiving signal processing circuit. Moreover, the calibration devices are only compatible with receiving coils of specific specifications and sizes. Therefore, the present invention proposes a method for calibrating the sensitivity of the receiving module of an electromagnetic positioning and tracking system. This method does not restrict the specifications and sizes of the receiving coil and includes the receiving signal processing circuit. This method effectively avoids the impact of differences in the device parameters of the receiving signal processing circuit on positioning accuracy, and has important application value in improving the absolute positioning accuracy of the electromagnetic positioning and tracking system. Summary of the Invention

[0010] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the structures particularly pointed out in the description and other drawings.

[0011] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method and system for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system.

[0012] To achieve the above objectives, the technical solution of the present invention is: a method for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system, comprising:

[0013] Construction of calibration space, construction of a stable magnetic field calibration space with controllable frequency and intensity;

[0014] Acquisition of the measured object data: the measured object is placed in the calibration space, the measured object senses the magnetic field signal of the calibration space through the receiving coil, and the magnetic field signal is processed to obtain the measured object data;

[0015] Calculation of sensitivity parameters of the object under test, calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object under test;

[0016] Among them, the calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier.

[0017] In the calibration space, a function signal generator generates a standard excitation signal with user-adjustable amplitude and frequency. A regulated power supply provides stable power input to the power amplifier. The power amplifier uses a constant current source mode to amplify the function signal generator's input voltage signal and output a controllable current signal. This current signal is applied to a Helmholtz coil of specific specifications (designed and manufactured based on the required magnetic field magnitude and excitation signal parameters), thereby generating a stable magnetic field with controllable frequency and intensity. The controllable magnetic field parameters include magnetic field magnitude and frequency. The magnetic field magnitude is controlled by the amplitude of the applied signal generator output signal, and the magnetic field frequency is determined by the applied signal frequency.

[0018] The present invention constructs a calibration space, places the object to be measured in the calibration space to obtain the data of the object to be measured, and finally calculates the sensitivity parameters of the object to be measured to achieve accurate calibration of the sensitivity of the receiving module of the electromagnetic positioning and tracking system. The calibration method of the present invention does not limit the specifications and dimensions of the receiving coil and the calibration includes the receiving signal processing circuit part, which effectively avoids the influence of the device parameter differences of the receiving signal processing circuit on the positioning accuracy, and has important application value for improving the absolute positioning accuracy of the electromagnetic positioning and tracking system.

[0019] In some embodiments, the measured object data is measurement data recorded by a receiving module on a PC. This measurement data is obtained by the measured object sensing a magnetic field signal in a calibration space via a receiving coil, processing the magnetic field signal, and transmitting it to the PC. Specifically, the PC is connected to the measured object via a USB interface, and the measured object uploads the magnetic field measurement data to the PC via the USB interface. The PC then records and stores the valid data generated during the calibration process in real time.

[0020] In some embodiments, the sensitivity under different magnetic field strengths is calculated, and plotted and fitted to obtain the sensitivity parameters of the object under test; specifically:

[0021] According to the specifications and dimensions of the Helmholtz coil, the constant of the Helmholtz coil is calculated;

[0022] The magnetic field strength under the current is calculated based on the effective value of the coil current and the constant of the Helmholtz coil;

[0023] Calculate the sensitivity parameters under the current magnetic field strength based on the receiving module test data under the corresponding test conditions recorded on the PC.

[0024] Repeatedly calculate the magnetic field strength under the current current and the sensitivity parameters under the current magnetic field strength to obtain the sensitivity under different magnetic field strengths;

[0025] The sensitivity under different magnetic field intensities obtained in the above process is plotted and fitted, and the slope of the fitted curve is the final sensitivity parameter of the measured object.

[0026] In some embodiments, the effective value of the coil current is obtained by measuring the effective value of the current of the Helmholtz coil using a high-precision digital multimeter disposed between the power amplifier and the Helmholtz coil.

[0027] In some embodiments, the Helmholtz coil constant is calculated as:

[0028] ,

[0029] Where K is the Helmholtz coil constant, which is determined by the specifications of the Helmholtz coil; N is the number of turns of the single-sided winding of the Helmholtz coil; x is the radius of the coil winding, in meters; y is half the center distance between the two series coil windings, in meters.

[0030] In some embodiments, the calculation formula for the magnetic field strength under the current is:

[0031] ,

[0032] Where H is the magnetic field, in A / m; K is the Helmholtz coil constant, which is determined by the dimensions of the Helmholtz coil; and I is the amplitude of the current applied to the coil, in A.

[0033] In some embodiments, the sensitivity parameter is calculated as:

[0034] ,

[0035] Where, The sensitivity of the calibrated receiving module, in mV / uT; This is the measurement data of the receiving module recorded on the PC, in mV. I It is the effective value of the Helmholtz coil current measured by a high-precision digital multimeter, in A.

[0036] In some embodiments, the object under test is placed in a calibration space, the object under test senses a magnetic field signal in the calibration space through a receiving coil, and the magnetic field signal is processed to obtain the object under test data; specifically:

[0037] According to the magnetic field frequency and magnetic field size required for calibration, set the output frequency and amplitude of the function signal generator;

[0038] Place the object under test in the calibration space of the Helmholtz coil and shake it arbitrarily;

[0039] Run the data display and storage code on the PC to display and record the measured data output by the measured object in real time;

[0040] Record the signal frequency and amplitude of the current function signal generator;

[0041] According to the specific requirements of the test under multiple magnetic field strengths, adjust the output amplitude of the signal generator, repeat the above operation process, and complete the measurement values ​​of all set signal amplitudes.

[0042] In some embodiments, the Helmholtz coil is a coil group structure consisting of two series windings.

[0043] In some embodiments, the object under test contains a three-axis orthogonal receiving coil.

[0044] The present invention also provides a system for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system, comprising:

[0045] A construction module for constructing a stable magnetic field calibration space with controllable frequency and intensity;

[0046] An acquisition module is used to place the object under test in the calibration space, and the object under test senses the magnetic field signal of the calibration space through the receiving coil and processes the magnetic field signal to obtain the data of the object under test;

[0047] A calculation module is used to calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object under test;

[0048] Among them, the calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier.

[0049] In summary, the beneficial effects of the present invention are:

[0050] 1. The present invention can accurately calibrate the sensitivity of the receiving module of the electromagnetic positioning and tracking system under different magnetic field intensities, and obtain the optimal calibration parameters through calibration curve fitting and correction, effectively improving the absolute positioning accuracy of the electromagnetic positioning and tracking system.

[0051] 2. This invention can integrate the calibration of the receiving module and the receiving coil into a whole. Compared with the traditional method of calibrating only the receiving coil, it can effectively avoid the impact of circuit parameter differences on positioning accuracy.

[0052] 3. The present invention uses Helmholtz coils to generate a stable magnetic field with controllable frequency and size, with a large calibration space and no restrictions on the size of the calibration object.

[0053] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0054] Undoubtedly, these and other objects of the present invention will become more apparent after the following detailed description of the preferred embodiment is described with reference to the various figures and drawings.

[0055] In order to make the above and other objects, features and advantages of the present invention more obvious and easy to understand, one or more preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention but do not constitute a limitation of the present invention.

[0057] In the drawings, like components are given like reference numerals, and the drawings are schematic and not necessarily drawn to scale.

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only one or several embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on such drawings without paying any creative work.

[0059] Figure 1 This is a schematic diagram of the calibration system structure of the present invention;

[0060] Figure 2 This is a schematic diagram of the placement of the object to be tested of the present invention;

[0061] Figure 3 Schematic diagram of the calibration method of the present invention;

[0062] Figure 4 Schematic diagram of the process of acquiring data of the measured object of the present invention;

[0063] Figure 5 Schematic diagram of the calculation process of the sensitivity parameters of the measured object in the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but are not intended to limit the present invention.

[0065] In addition, in the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] In the present invention, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed connections, removable connections, or integration; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal communication between two components or interactions between two components. However, the term "direct connection" indicates that the two connected entities are not connected through a transitional structure, but are connected solely through a connecting structure to form a single entity. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0068] Reference Figure 1-Figure 5 , Figure 1 This is a schematic diagram of the calibration system structure of the present invention; Figure 2 This is a schematic diagram of the placement of the object to be tested of the present invention; Figure 3 Schematic diagram of the calibration method of the present invention; Figure 4 Schematic diagram of the process of acquiring data of the measured object of the present invention; Figure 5 Schematic diagram of the calculation process of the sensitivity parameters of the measured object in the present invention.

[0069] According to some embodiments of the present invention, a method for calibrating the sensitivity of a receiving module of an electromagnetic positioning tracking system is provided. The calibration method comprises:

[0070] Construction of calibration space, construction of a stable magnetic field calibration space with controllable frequency and intensity;

[0071] Acquisition of the measured object data: the measured object is placed in the calibration space, the measured object senses the magnetic field signal of the calibration space through the receiving coil, and the magnetic field signal is processed to obtain the measured object data;

[0072] Calculation of sensitivity parameters of the object under test, calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object under test;

[0073] Among them, the calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier.

[0074] In the calibration space, a function signal generator generates a standard excitation signal with user-adjustable amplitude and frequency. A regulated power supply provides stable power input to the power amplifier. The power amplifier uses a constant current source mode to amplify the function signal generator's input voltage signal and output a controllable current signal. This current signal is applied to a Helmholtz coil of specific specifications (designed and manufactured based on the required magnetic field magnitude and excitation signal parameters), thereby generating a stable magnetic field with controllable frequency and intensity. The controllable magnetic field parameters include magnetic field magnitude and frequency. The magnetic field magnitude is controlled by the amplitude of the applied signal generator output signal, and the magnetic field frequency is determined by the applied signal frequency.

[0075] The present invention constructs a calibration space, places the object to be measured in the calibration space to obtain the data of the object to be measured, and finally calculates the sensitivity parameters of the object to be measured to achieve accurate calibration of the sensitivity of the receiving module of the electromagnetic positioning and tracking system. The calibration method of the present invention does not limit the specifications and dimensions of the receiving coil and the calibration includes the receiving signal processing circuit part, which effectively avoids the influence of the device parameter differences of the receiving signal processing circuit on the positioning accuracy, and has important application value for improving the absolute positioning accuracy of the electromagnetic positioning and tracking system.

[0076] According to some embodiments of the present invention, the measured object data may optionally be measurement data of a receiving module recorded by a PC. The measurement data of the receiving module recorded by the PC is obtained by the measured object sensing a magnetic field signal in a calibration space via a receiving coil, processing the magnetic field signal, and transmitting it to the PC. Specifically, the PC is connected to the measured object via a USB interface, and the measured object uploads the magnetic field measurement data to the PC via the USB interface. The PC then records and stores the valid data generated during the calibration process in real time.

[0077] According to some embodiments of the present invention, optionally, the sensitivity under different magnetic field strengths is calculated, and plotted and fitted to obtain the sensitivity parameters of the object under test; specifically:

[0078] According to the specifications and dimensions of the Helmholtz coil, the constant of the Helmholtz coil is calculated;

[0079] The magnetic field strength under the current is calculated based on the effective value of the coil current and the constant of the Helmholtz coil;

[0080] Calculate the sensitivity parameters under the current magnetic field strength based on the receiving module test data under the corresponding test conditions recorded on the PC.

[0081] Repeatedly calculate the magnetic field strength under the current current and the sensitivity parameters under the current magnetic field strength to obtain the sensitivity under different magnetic field strengths;

[0082] The sensitivity under different magnetic field intensities obtained in the above process is plotted and fitted, and the slope of the fitted curve is the final sensitivity parameter of the measured object.

[0083] According to some embodiments of the present invention, optionally, the effective value of the coil current is obtained by measuring the effective value of the current of the Helmholtz coil using a high-precision digital multimeter disposed between the power amplifier and the Helmholtz coil.

[0084] According to some embodiments of the present invention, optionally, the calculation formula of the constant of the Helmholtz coil is:

[0085] ,

[0086] Where K is the Helmholtz coil constant, which is determined by the specifications of the Helmholtz coil; N is the number of turns of the single-sided winding of the Helmholtz coil; x is the radius of the coil winding, in meters; y is half the center distance between the two series coil windings, in meters.

[0087] In some embodiments, the calculation formula for the magnetic field strength under the current is:

[0088] ,

[0089] Where H is the magnetic field, in A / m; K is the Helmholtz coil constant, which is determined by the dimensions of the Helmholtz coil; and I is the amplitude of the current applied to the coil, in A.

[0090] According to some embodiments of the present invention, optionally, the calculation formula of the sensitivity parameter is:

[0091] ,

[0092] Where, The sensitivity of the calibrated receiving module, in mV / uT; This is the measurement data of the receiving module recorded on the PC, in mV. I It is the effective value of the Helmholtz coil current measured by a high-precision digital multimeter, in A.

[0093] According to some embodiments of the present invention, the object under test is optionally placed in a calibration space, the object under test senses a magnetic field signal in the calibration space through a receiving coil, and the magnetic field signal is processed to obtain the object under test data; specifically:

[0094] According to the magnetic field frequency and magnetic field size required for calibration, set the output frequency and amplitude of the function signal generator;

[0095] Place the object under test in the calibration space of the Helmholtz coil and shake it arbitrarily;

[0096] Run the data display and storage code on the PC to display and record the measured data output by the measured object in real time;

[0097] Record the signal frequency and amplitude of the current function signal generator;

[0098] According to the specific requirements of the test under multiple magnetic field strengths, adjust the output amplitude of the signal generator, repeat the above operation process, and complete the measurement values ​​of all set signal amplitudes.

[0099] According to some embodiments of the present invention, optionally, the Helmholtz coil is a coil group structure consisting of two series windings.

[0100] According to some embodiments of the present invention, optionally, the object under test contains a three-axis orthogonal receiving coil.

[0101] According to some embodiments of the present invention, the present invention also provides a calibration system for the sensitivity of a receiving module in an electromagnetic positioning and tracking system. The calibration system includes a construction module, an acquisition module, and a calculation module. The construction module is used to construct a calibration space with a stable magnetic field with controllable frequency and intensity. The acquisition module is used to place a measured object in the calibration space. The measured object senses the magnetic field signal in the calibration space through a receiving coil and processes the magnetic field signal to obtain measured object data. The calculation module is used to calculate the sensitivity under different magnetic field intensities, and perform plotting and fitting to obtain the sensitivity parameters of the measured object. The calibration space includes a function signal generator, a power amplifier, a regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the regulated power supply is connected to the power amplifier.

[0102] Example 1

[0103] This embodiment provides a method for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system. The calibration method includes:

[0104] The calibration space is constructed to create a stable magnetic field calibration space with controllable frequency and intensity. The calibration space includes a function signal generator, a power amplifier, a regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the regulated power supply is connected to the power amplifier.

[0105] To obtain the data of the measured object, the measured object is placed in the calibration space. The measured object senses the magnetic field signal of the calibration space through the receiving coil and processes the magnetic field signal (the receiving coil is placed in the magnetic field of the calibration space and converts the magnetic field signal of the calibration space into a voltage signal. The voltage signal is a time domain signal. The measurement signal is converted to the frequency domain through Fourier transform, and the corresponding amplitude data of the calibration frequency is extracted) to obtain the measured object data. Specifically:

[0106] According to the magnetic field frequency and magnetic field size required for calibration, set the output frequency and amplitude of the function signal generator;

[0107] Place the object under test in the calibration space of the Helmholtz coil and shake it arbitrarily;

[0108] Run the data display and storage code on the PC to display and record the measured data output by the measured object in real time;

[0109] Record the signal frequency and amplitude of the current function signal generator;

[0110] According to the specific requirements of the test under multiple magnetic field strengths, adjust the output amplitude of the signal generator, repeat the above operation process, and complete the measurement values ​​of all set signal amplitudes.

[0111] Calculate the sensitivity parameters of the object being measured, calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object being measured. Specifically:

[0112] According to the specifications and dimensions of the Helmholtz coil, the constant of the Helmholtz coil is calculated; the calculation formula of the constant of the Helmholtz coil is:

[0113] ,

[0114] Where K is the Helmholtz coil constant, which is determined by the size of the Helmholtz coil; N is the number of turns of the Helmholtz coil on one side; x is the radius of the coil winding, in meters; y is half the center distance between the two series coil windings, in meters;

[0115] The magnetic field strength under the current is calculated based on the effective value of the coil current and the constant of the Helmholtz coil;

[0116] Calculate the sensitivity parameters under the current magnetic field strength based on the receiving module test data under the corresponding test conditions recorded on the PC.

[0117] Repeatedly calculate the magnetic field strength under the current current and the sensitivity parameter under the current magnetic field strength to obtain the sensitivity under different magnetic field strengths. The calculation formula of the sensitivity parameter is:

[0118] ,

[0119] Where, The sensitivity of the calibrated receiving module, in mV / uT; is the receiving module measurement data recorded by the PC, in mV; I is the effective value of the Helmholtz coil current measured by a high-precision digital multimeter, in A;

[0120] The sensitivity under different magnetic field intensities obtained in the above process is plotted and fitted (the sensitivity parameters under different magnetic field intensities are measured and the calibration data is fitted using Matlab's curve fitting tool). The slope of the fitted curve is the final sensitivity parameter of the measured object.

[0121] Example 2

[0122] This embodiment provides a calibration system for the sensitivity of the receiving module of an electromagnetic positioning and tracking system. The calibration system includes a construction module, an acquisition module, and a calculation module. The construction module is used to construct a calibration space with a stable magnetic field with controllable frequency and intensity. The acquisition module is used to place the object under test in the calibration space. The object under test senses the magnetic field signal in the calibration space through the receiving coil and processes the magnetic field signal to obtain the object data. The calculation module is used to calculate the sensitivity under different magnetic field intensities, and perform plotting and fitting to obtain the sensitivity parameters of the object under test. The calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier.

[0123] It should be noted that many specific details are set forth in the above description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

Claims

1. A method for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system, characterized in that: include: Construction of calibration space, construction of a stable magnetic field calibration space with controllable frequency and intensity; Acquisition of the measured object data: the measured object is placed in the calibration space, the measured object senses the magnetic field signal of the calibration space through the receiving coil, and the magnetic field signal is processed to obtain the measured object data; Calculation of sensitivity parameters of the object under test, calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object under test; The calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier. Calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object being measured; specifically: According to the specifications and dimensions of the Helmholtz coil, the constant of the Helmholtz coil is calculated; The magnetic field strength under the current is calculated based on the effective value of the coil current and the constant of the Helmholtz coil; Calculate the sensitivity parameters under the current magnetic field strength based on the receiving module test data under the corresponding test conditions recorded on the PC. Repeatedly calculate the magnetic field strength under the current current and the sensitivity parameters under the current magnetic field strength to obtain the sensitivity under different magnetic field strengths; The sensitivity under different magnetic field intensities obtained in the above process is plotted and fitted, and the slope of the fitted curve is the final sensitivity parameter of the measured object.

2. The method for calibrating the sensitivity of the receiving module of the electromagnetic positioning tracking system according to claim 1, characterized in that: The measured object data is the receiving module measurement data recorded by the PC. The receiving module measurement data recorded by the PC is obtained by the measured object sensing the magnetic field signal of the calibration space through the receiving coil and transmitting the processed magnetic field signal to the PC.

3. The method for calibrating the sensitivity of the receiving module of the electromagnetic positioning tracking system according to claim 1, characterized in that: The effective value of the coil current is obtained by measuring the effective value of the current of the Helmholtz coil using a high-precision digital multimeter arranged between the power amplifier and the Helmholtz coil.

4. The method for calibrating the sensitivity of the receiving module of the electromagnetic positioning tracking system according to claim 1, characterized in that: The formula for calculating the constant of the Helmholtz coil is: ， Where K is the Helmholtz coil constant, which is determined by the specifications of the Helmholtz coil; N is the number of turns of the single-sided winding of the Helmholtz coil; x is the radius of the coil winding, in meters; y is half the center distance between the two series coil windings, in meters.

5. The method for calibrating the sensitivity of the receiving module of the electromagnetic positioning tracking system according to claim 4, characterized in that: The calculation formula for the magnetic field strength under the current is: ， Where H is the magnetic field, in A / m; K is the Helmholtz coil constant, which is determined by the dimensions of the Helmholtz coil; and I is the amplitude of the current applied to the coil, in A.

6. The method for calibrating the sensitivity of the receiving module of the electromagnetic positioning tracking system according to claim 5, characterized in that: The calculation formula of the sensitivity parameter is: ， Where, The sensitivity of the calibrated receiving module, in mV / uT; This is the measurement data of the receiving module recorded by the PC, in mV. It is the effective value of the Helmholtz coil current measured by a high-precision digital multimeter, in A.

7. The method for calibrating the sensitivity of a receiving module of an electromagnetic positioning tracking system according to claim 1, characterized in that: The object under test is placed in the calibration space. The object under test senses the magnetic field signal of the calibration space through the receiving coil and processes the magnetic field signal to obtain the data of the object under test. Specifically: According to the magnetic field frequency and magnetic field size required for calibration, set the output frequency and amplitude of the function signal generator; Place the object under test in the calibration space of the Helmholtz coil and shake it arbitrarily; Run the data display and storage code on the PC to display and record the measured data output by the measured object in real time; Record the signal frequency and amplitude of the current function signal generator; According to the specific requirements of the test under multiple magnetic field strengths, adjust the output amplitude of the signal generator, repeat the above operation process, and complete the measurement values ​​of all set signal amplitudes.

8. The method for calibrating the sensitivity of a receiving module of an electromagnetic positioning tracking system according to claim 1, characterized in that: A Helmholtz coil is a coil structure consisting of two series windings.

9. The method for calibrating the sensitivity of a receiving module of an electromagnetic positioning tracking system according to claim 1, characterized in that: The object under test contains three-axis orthogonal receiving coils.

10. A system for calibrating the sensitivity of a receiving module of an electromagnetic positioning and tracking system, characterized in that: include: A construction module for constructing a stable magnetic field calibration space with controllable frequency and intensity; An acquisition module is used to place the object under test in the calibration space, and the object under test senses the magnetic field signal of the calibration space through the receiving coil and processes the magnetic field signal to obtain the data of the object under test; A calculation module is used to calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object under test; The calibration space includes a function signal generator, a power amplifier, a voltage-regulated power supply, and a Helmholtz coil. The channel output of the function signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the Helmholtz coil, and the voltage-regulated power supply is connected to the power amplifier. Calculate the sensitivity under different magnetic field strengths, and perform plotting and fitting to obtain the sensitivity parameters of the object being measured; specifically: According to the specifications and dimensions of the Helmholtz coil, the constant of the Helmholtz coil is calculated; The magnetic field strength under the current is calculated based on the effective value of the coil current and the constant of the Helmholtz coil; Calculate the sensitivity parameters under the current magnetic field strength based on the receiving module test data under the corresponding test conditions recorded on the PC. Repeatedly calculate the magnetic field strength under the current current and the sensitivity parameters under the current magnetic field strength to obtain the sensitivity under different magnetic field strengths; The sensitivity under different magnetic field intensities obtained in the above process is plotted and fitted, and the slope of the fitted curve is the final sensitivity parameter of the measured object.

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