Six-degree-of-freedom wireless magnetic positioning system, method and apparatus based on soft magnet

Abstract

The application discloses a kind of six degrees of freedom wireless magnetic positioning system, method and device based on soft magnet, wherein system includes: magnetic source module, for generating alternating magnetic field;Soft magnet, installed at the end of measured instrument, and the measured instrument with the soft magnet uses rigid connection, to make force and torque suffered by soft magnet pass to measured instrument;The soft magnet works in alternating magnetic field;Magnetic field detection device, for detecting the magnetic field change due to the movement of the soft magnet;Processor, according to the measured magnetic field change to soft magnet pose measurement, obtain the pose of soft magnet, according to the pose of soft magnet to calculate the pose of measured instrument end.The application uses soft magnet as passive sensitive element, and the soft magnet is rigidly connected with the measured instrument, which realizes the non-contact sensing of the end of the measured instrument and the safe, stable and accurate six degrees of freedom real-time pose measurement.The application can be widely applied in the field of position tracking and positioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of position tracking and positioning, and in particular to a six-degree-of-freedom wireless magnetic positioning system, method and device based on soft magnetic body. BACKGROUND

[0002] Medical robots and other automated medical devices and equipment have been increasingly widely used in medical tasks such as disease diagnosis, biopsy sampling, surgical treatment, etc., which can effectively improve the accuracy, stability and safety of medical operations, reduce medical costs, and reduce the work burden of medical personnel. For example, minimally invasive medical instruments can well adapt to complex and narrow internal space, further reduce patient trauma, improve the safety of surgery, and reduce postoperative adverse reactions of patients. Real-time tracking and measurement of the pose of the end effector of the minimally invasive medical instrument can achieve state monitoring, autonomous navigation and feedback control, guiding doctors to operate the instrument more efficiently and accurately to reach the lesion, thereby greatly improving the safety, accuracy and automation level of minimally invasive medical operations.

[0003] The most widely used optical tracking system in existing minimally invasive medical instrument end pose tracking methods is affected by line-of-sight obstruction and cannot sense the minimally invasive medical instrument moving in the body; pose tracking methods based on other sensing principles have their own limitations and deficiencies in safety, stability and measurement accuracy, etc., and are difficult to be widely used. Magnetic field can safely penetrate the human body, and pose tracking methods based on magnetic field sensing principle can be used to track minimally invasive medical instruments moving in the body. However, existing positioning methods based on electromagnet or permanent magnet magnetic sources have their own limitations in system integration reliability, magnetic interference resistance and full six-degree-of-freedom pose sensing capability, which seriously restricts the application of magnetic positioning technology in minimally invasive medical instrument positioning. SUMMARY

[0004] To at least partially solve one of the technical problems existing in the prior art, the purpose of the present application is to provide a six-degree-of-freedom wireless magnetic positioning system, method and device based on soft magnetic body.

[0005] The technical solution adopted by the present application is:

[0006] A six-degree-of-freedom wireless magnetic positioning system based on soft magnetic body, comprising:

[0007] A magnetic source module for generating an alternating magnetic field;

[0008] A soft magnetic body mounted at the end of a measured instrument, and the measured instrument and the soft magnetic body are rigidly connected so that the force and torque acting on the soft magnetic body are transmitted to the measured instrument; the soft magnetic body works in an alternating magnetic field;

[0009] A magnetic field detection device for detecting a magnetic field change caused by movement of the soft magnet;

[0010] A processor for measuring the pose of the soft magnet according to the detected magnetic field change, obtaining the pose of the soft magnet, and calculating the pose of the end of the measured instrument according to the pose of the soft magnet.

[0011] Further, the magnetic field detection device comprises:

[0012] A magnetic sensor for converting the magnetic induction intensity into a differential voltage signal;

[0013] A signal processing unit for pre-processing the differential voltage signal and outputting.

[0014] Further, the magnetic sensor is a dual three-axis tunnel magnetoresistance sensor.

[0015] Further, the material of the soft magnet is a nickel-iron magnetic alloy or a nickel-iron amorphous alloy.

[0016] Further, the shape of the soft magnet is an ellipsoid, an elliptic cylinder or a cuboid, and the three axes are asymmetric, i.e., the equatorial radii a and b and the polar radius (height) c are not equal, and a > b > c.

[0017] Another technical solution adopted by the present application is:

[0018] A six-degree-of-freedom wireless magnetic positioning method based on a soft magnet, comprising the following steps:

[0019] Establishing a mathematical relationship model between the magnetic field measurement value and the pose of the soft magnet;

[0020] Establishing a kinematic model of the end of the measured instrument;

[0021] Detecting the magnetic field change caused by the translation and / or rotation of the soft magnet in the alternating magnetic field;

[0022] Combining the kinematic model and the mathematical relationship model to analyze the data of the magnetic field change and estimate the pose of the soft magnet;

[0023] According to the pose of the soft magnet, the pose of the end of the measured instrument is calculated.

[0024] Further, the mathematical relationship model is specifically:

[0025] It is assumed that the magnetic source and the magnetized soft magnet can be approximated by a magnetic dipole model:

[0026]

[0027] where subscript s denotes the magnetic sensor; e denotes the magnetic source; μ denotes the soft magnet; h(·) denotes the magnetic dipole field strength distribution model; P denotes the position vector of the soft magnet in the world coordinate system; R denotes the soft magnet attitude rotation matrix; k denotes the demagnetization coefficient of the soft magnet; denotes the magnetic field of the electromagnet detected by the sensor, h μ (·) denotes the magnetic dipole model of the soft magnet, h e (·) denotes the magnetic dipole model of the electromagnet, denotes the diagonal matrix of the demagnetization coefficient of the soft magnet, denotes the rotation matrix from the soft magnet system to the electromagnet system, denotes the magnetic moment of the electromagnet, denotes the position vector of the electromagnet pointing to the soft magnet, denotes the position vector of the electromagnet pointing to the sensor, denotes the position vector of the soft magnet pointing to the sensor.

[0028] Further, the kinematic model is established based on a constant velocity model, and the state quantity parameters to be estimated include three-dimensional coordinates of the soft magnet, three-axis direction velocity components, attitude quaternions of the soft magnet, and three-axis angular velocity components, and are represented as follows:

[0029]

[0030] In the formula, P = [xyz] T denotes the three-axis position vector of the soft magnet, v = [v x v y v z T denotes the three-axis velocity component of the soft magnet, Q = [q0q1q2q3] T denotes the attitude quaternion of the soft magnet, ω = [ω x ω y ω z T denotes the three-axis angular velocity component of the soft magnet;

[0031] The magnetic field measurement value is given by a three-axis magnetic sensor (two sensors are used here):

[0032] Y = [B x1 B y1 B z1 B x2 B y2 B z2 T

[0033] The pose tracking algorithm used is extended Kalman filtering, and the state equation and magnetic field measurement equation of the system are established:

[0034] X​​​k = Φ k-1 X k-1 + Gw k-1

[0035] Y k = h(X k ) + n k

[0036] State equation is expanded as:

[0037] X k = ΦX k-1 + Gw k-1

[0038]

[0039] In the formula, P k represents the position at time k, v k represents the velocity at time k, q k represents the attitude at time k, ω k represents the angular velocity at time k, I 3×3 represents a three-order unit matrix, Δt represents a sampling time interval, h(X k ) represents a system measurement model, n k represents measurement noise.

[0040] Further, the six-degree-of-freedom wireless magnetic positioning method further comprises the following steps:

[0041] A global coordinate system is established, and all devices are expressed in a unified coordinate.

[0042] Another technical solution adopted by the application is:

[0043] A six-degree-of-freedom wireless magnetic positioning device based on a soft magnetic body, comprising:

[0044] At least one processor;

[0045] At least one memory for storing at least one program;

[0046] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0047] The application has the beneficial effect that the application uses a soft magnetic body as a passive sensitive element, rigidly connects the soft magnetic body with a measured instrument, realizes non-contact sensing of the end of the measured instrument, and realizes safe, stable, and accurate six-degree-of-freedom real-time pose measurement. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following introduces the drawings of the related technical solutions in the embodiments of the present application or the prior art. It should be understood that the drawings in the following introduction are only for facilitating the clear description of part of the embodiments of the technical solutions of the present application, and for those skilled in the art, other drawings can also be obtained without paying creative labor on the premise.

[0049] Figure 1 is a flow chart of a six-degree-of-freedom wireless magnetic positioning based on soft magnetic bodies in the embodiments of the present application;

[0050] Figure 2 is a structural schematic diagram of a six-degree-of-freedom wireless magnetic positioning system of a minimally invasive medical instrument based on soft magnetic bodies in the embodiments of the present application;

[0051] Figure 3 is a comparison schematic diagram of the estimated value of the rotation angle and the reference value obtained in the embodiments of the present application;

[0052] Figure 4 is a comparison schematic diagram of the estimated value of the coordinates and the reference value obtained in the embodiments of the present application.

[0053] The reference signs: 1, magnetic source; 2, power supply module; 3, power amplifier; 4, soft magnetic body; 5, magnetic sensor; 6, signal processing module; 7, computer; 8, signal generator; 9, minimally invasive medical instrument. DETAILED DESCRIPTION

[0054] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. For the step numbers in the following embodiments, they are only set for facilitating the description and explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0055] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for facilitating the description of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0056] In the description of the present application, the meaning of one or more is one or more, the meaning of multiple is more than two, greater than, less than, more than, etc. is understood as not including the number, above, below, etc. is understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0057] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical scheme.

[0058] The soft magnet is a ferromagnetic body with high magnetic permeability and low coercivity, which is easily magnetized by an external magnetic field to become a magnetic source, and can be subjected to force and torque in an external magnetic field. Therefore, the soft magnet is fixed on the medical instrument as a force element to drive the medical instrument. The electromagnetic coil as a driving magnetic source is placed outside the body, and the soft magnet is magnetized by the magnetic field emitted by the driving magnetic source to form a secondary magnetic source, and the magnetic moment (reflecting the magnetic intensity and orientation) depends on the magnetic field of the driving magnetic source magnetizing it at the position of the soft magnet. The magnetized soft magnet can be regarded as a dipole magnetic source, and the soft magnet will be subjected to torque and force in the driving magnetic field, which depends on the local magnetic field and the magnetic field gradient; by adjusting the external driving magnetic field and designing the geometry of the soft magnet, three-degree-of-freedom force and three-degree-of-freedom torque are applied to the end of the minimally invasive instrument, thereby realizing full six-degree-of-freedom dexterous driving. Therefore, after understanding the magnetic-force coupling relationship of the soft magnet in the driving magnetic field, combined with the driving control system, the micro medical instrument or other industrial micro robots can be precisely controlled.

[0059] Referring to Figure 2 The embodiment provides a six-degree-of-freedom wireless magnetic positioning system based on a soft magnet, which comprises:

[0060] A magnetic source module is used for generating an alternating magnetic field.

[0061] A soft magnet is installed at the end of the measured instrument, and the measured instrument and the soft magnet are rigidly connected; the soft magnet works in an alternating magnetic field; wherein the soft magnet is magnetized to form a secondary magnetic source under the action of the magnetic field of the magnetic source, and the magnetic moment depends on the external magnetic field at the position of the soft magnet. The magnetized soft magnet is subjected to force and torque under the action of the external magnetic field, and then drives the measured instrument to translate and rotate;

[0062] A magnetic field detection device is used for detecting the change of the magnetic field caused by the movement of the soft magnet.

[0063] The processor measures the pose of the soft magnet according to the detected magnetic field change, obtains the pose of the soft magnet, and calculates the pose of the end of the measured instrument according to the pose of the soft magnet.

[0064] As an optional implementation, the material of the soft magnet is nickel-iron magnetic alloy (1J85) or nickel-iron amorphous alloy (1K501), and the relative magnetic permeability μ r = 10 4 -10 5 ; the shape is an ellipsoid or an elliptical cylinder or a cuboid, and the three axes are asymmetric, that is, the equatorial radii a and b and the polar radius (height) c are not equal, and a > b > c.

[0065] As an optional implementation, the magnetic field detection device comprises:

[0066] A magnetic sensor is used to convert the magnetic induction intensity into a differential voltage signal;

[0067] A signal processing unit is used to preprocess the differential voltage signal and output.

[0068] The magnetic sensor used is a double-channel three-axis tunnel magnetoresistance (TMR) sensor, and the distance between the two sensors is 120 mm; the distance between the magnetic source and the sensor is 200 mm.

[0069] As an optional implementation, the magnetic source is an electromagnet, the coil diameter is 100 mm, and the number of turns is 1000; the generated magnetic field is an alternating magnetic field with a frequency of 300 Hz.

[0070] The above system is explained in detail in combination with the drawings and specific embodiments. In this embodiment, nickel-iron magnetic alloy (1J85) is used as the material to process an elliptical cylindrical soft magnet, and the relative magnetic permeability μ r = 1.246 x 10 5 -4. The three-axis lengths are: a = 8 mm, b = 16 mm, and c = 40 mm. The magnetic sensor used is a TMR3205M three-axis linear TMR sensor from Jiangsu Duowei Technology Co., Ltd.

[0071] As Figure 2 shown, the embodiment provides a six-degree-of-freedom wireless magnetic positioning system for minimally invasive medical instruments based on a soft magnet, which comprises a magnetic source module 1, a power supply module 2, a power amplifier 3, a soft magnet 4, a magnetic sensor 5, a signal processing module 6, a computer 7, a signal generator 8, and a minimally invasive medical instrument 9.

[0072] The soft magnet 4 is rigidly connected to the working end of the minimally invasive medical instrument 9, and the soft magnet 4 performs translational and rotational movement in the effective working area between the magnetic source module 1 and the magnetic sensor 5. The 24V DC power output by the power supply module 2 is converted into sinusoidal alternating current with a frequency of 300Hz and an amplitude of 24Vpp after passing through the power amplifier 3, and the sinusoidal alternating current is used to power the magnetic source module 1 to generate an alternating magnetic field.

[0073] The magnetic field change caused by the movement of the soft magnet 4 in the magnetic field is detected by the magnetic sensor 5, and the detected magnetic change signal is filtered, amplified, and effectively valued by the signal processing module 6, and then transmitted to the computer 7 through the cable by the serial communication mode.

[0074] The computer 7 receives the signal from the magnetic sensor 5, estimates the pose of the soft magnet 4 according to the established mathematical model of the magnetic field measurement value and the pose of the soft magnet 4, and the kinematic model of the end of the minimally invasive medical instrument 9. Since the soft magnet 4 is rigidly connected to the end of the minimally invasive medical instrument 9, the pose of the end of the minimally invasive medical instrument to be measured can be calculated by measuring the pose of the soft magnet.

[0075] As an optional implementation, after obtaining the pose of the end of the minimally invasive medical instrument, the computer 7 compares the obtained pose of the end of the minimally invasive medical instrument with the predicted target pose, judges whether the minimally invasive medical instrument reaches the preset position, and if it is detected that it does not reach the bottom, the working parameters of the magnetic source module are updated to promote the movement of the minimally invasive instrument until the minimally invasive instrument reaches the target pose.

[0076] As an optional implementation, the power supply module is placed behind the magnetic source module, and the signal generator and the power amplifier are used to power the magnetic source module. The magnetic field detection device is arranged in front of the magnetic source module. The effective working area of the soft magnet is located between the magnetic source module and the magnetic field detection device.

[0077] Based on the above system, as shown in Figure 1 The embodiment provides a six-degree-of-freedom wireless magnetic positioning method based on a soft magnet, which comprises the following steps:

[0078] S1, a global coordinate system is established, and all devices are expressed in a unified coordinate.

[0079] S2, a mathematical relationship model between the magnetic field measurement value and the pose of the soft magnet is established.

[0080] S3, a kinematic model of the end of the measured instrument is established.

[0081] S4, detecting the magnetic field change caused by the translation and / or rotation of the soft magnet in the alternating magnetic field.

[0082] S5, analyze the data of magnetic field change combined with the kinematics model and the mathematical relationship model, and estimate the pose of the soft magnet.

[0083] S6, calculate the pose of the end of the measured instrument according to the pose of the soft magnet.

[0084] Since the soft magnet moves translationally and rotationally between the magnetic source and the magnetic field measuring device, it causes the magnetic field to change, and the magnetic field change is detected by the magnetic field measuring device, and the six-degree-of-freedom coordinate position and attitude of the soft magnet in the global coordinate system are estimated. The soft magnet and the end of the minimally invasive medical instrument are rigidly connected, and the pose of the end of the minimally invasive medical instrument to be measured can be calculated by measuring the pose of the soft magnet. In addition, by adjusting the external driving magnetic field and designing the geometry of the soft magnet, three-degree-of-freedom force and three-degree-of-freedom torque are applied to the end of the minimally invasive instrument, thereby achieving full six-degree-of-freedom dexterous driving.

[0085] The mathematical model established in step S2 is:

[0086] It is assumed that the magnetic source and the magnetized soft magnet can be approximated by a magnetic dipole model:

[0087]

[0088] wherein subscript s represents a magnetic sensor; e represents a magnetic source; μ represents a soft magnet; h(·) represents a dipole magnetic field intensity distribution model; P represents a position vector of the soft magnet in the world coordinate system; R represents a soft magnet attitude rotation matrix; k represents a demagnetization coefficient of the soft magnet; h s represents the electromagnet magnetic field detected by the sensor, h μ h μ (·) represents the magnetic dipole model of the soft magnet, h e h e (·) represents the magnetic dipole model of the electromagnet, k represents the diagonal matrix of the demagnetization coefficient of the soft magnet, R μe represents the rotation matrix from the soft magnet system to the electromagnet system, μ e represents the magnetic moment of the electromagnet, P e represents the position vector of the electromagnet pointing to the soft magnet, P e represents the position vector of the electromagnet pointing to the sensor, P μ represents the position vector of the soft magnet pointing to the sensor.

[0089] In step S3, the kinematics model is established based on the constant velocity model, and the state parameters to be estimated include the three-dimensional coordinates of the soft magnet, the velocity components of the three-axis direction, the attitude quaternion of the soft magnet, and the three-axis angular velocity components, which are represented as follows:

[0090] X = [P v Q ω] T

[0091] = [xyzv x vy v z q0q1q2q3ω x ω y ω z ] T

[0092] In the formula, P = [xyz] T represents the three-axis position vector of the soft magnet, v = [v x v y v z ] T represents the three-axis velocity component of the soft magnet, Q = [q0q1q2q3] T represents the attitude quaternion of the soft magnet, ω = [ω x ω y ω z ] T represents the three-axis angular velocity component of the soft magnet;

[0093] The magnetic field measurement value is given by the three-axis magnetic sensor:

[0094] Y = [B x1 B y1 B z1 B x2 B y2 B z2 ] T

[0095] The pose tracking algorithm used is extended Kalman filtering, and the state equation and magnetic field of the system are established:

[0096] X k = Φ k-1 X k-1 + Gw k-1

[0097] Y k = h (X k ) + n k

[0098] The state equation is expanded as:

[0099] X k = ΦX k-1 + Gw k-1

[0100]

[0101] Through experiments, Figure 3 is a schematic diagram of the comparison of the rotation angle estimation value obtained by the above method and the reference value, Figure 4The schematic diagram of the position estimation value obtained by the method and the reference value is shown in the figure. It can be seen that the method of the embodiment can accurately measure the six-degree-of-freedom real-time pose of the distal end of the minimally invasive medical instrument, and lays a foundation for precisely controlling the minimally invasive medical instrument.

[0102] The embodiment also provides a six-degree-of-freedom wireless magnetic positioning device based on a soft magnet, comprising:

[0103] at least one processor;

[0104] at least one memory for storing at least one program;

[0105] When the at least one program is executed by the at least one processor, the at least one processor implements Figure 1 the method.

[0106] The six-degree-of-freedom wireless magnetic positioning device based on a soft magnet of the embodiment can execute the six-degree-of-freedom wireless magnetic positioning method based on a soft magnet of the method embodiment, can execute the steps of any combination of the method embodiment, and has the corresponding functions and beneficial effects of the method.

[0107] The embodiment of the application also discloses a computer program product or a computer program, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device can read the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes Figure 1 the method.

[0108] In some alternative embodiments, the functions / operations mentioned in the block diagram can not occur in the order mentioned in the operation diagram. For example, depending on the functions / operations involved, two blocks shown in succession can actually be executed substantially simultaneously or the blocks can sometimes be executed in reverse order. In addition, the embodiments presented and described in the flowcharts of the application are provided by way of example, and the purpose is to provide a more comprehensive understanding of the technology. The disclosed method is not limited to the operations and logical flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and in which sub-operations described as part of larger operations are independently executed.

[0109] Furthermore, although the present application is described in the context of functional modules, it is to be understood that one or more of the described functions and / or features can be integrated in a single physical device and / or software module, or one or more functions and / or features can be implemented in separate physical devices or software modules. It will also be appreciated that detailed discussion of the actual implementation of each module is not necessary to an understanding of the application. Rather, the actual implementation of the modules, in combination with their attributes, functions, and internal relationships, are to be understood within the context of the devices disclosed herein. Thus, those skilled in the art with access to patents, scientific journals, and other public sources known by those skilled in the art will be able to practice the application as set forth in the claims without undue experimentation, using ordinary skill in the art along with the present disclosure. It is also to be understood that the specific concepts disclosed are merely illustrative and that the scope of the present application is to be determined by the entire scope of the claims, along with all equivalents of the claims and their equivalents.

[0110] If the functions are implemented in software, the functions can be stored in or implemented as one or more computer program products, which can be incorporated into a computer-readable medium for use by or in connection with an apparatus, method or system as described herein. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, or a computer-readable signal. The computer-readable medium can be, for example, but is not limited to, volatile or non-volatile memory, a floppy diskette, a compact disc read-only memory (CD-ROM), a magnetic tape, a flash drive, a hard disk drive, a programmable read-only memory (PROM), a random access memory (RAM), a reprogrammable read-only memory (REPROM) or a similar medium.

[0111] The logic and / or steps represented in the flowcharts and / or otherwise described herein, for example, can be embodied in non-transitory computer-readable media, which can be executed by an instruction execution system, apparatus, or device such as a computer-based system, a processor- based system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In this respect, the "computer-readable medium" can be any available medium or means that can contain, store, communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. By way of example, and not limitation, the computer-readable medium can comprise a computer-readable storage medium or a computer-readable signal medium.

[0112] More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can also be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, for example, via optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.

[0113] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the above described embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any of the following technologies, or combinations thereof, can be used with the necessary logic gates and circuitry for implementing logic functions on data signals: discrete logic circuitry having logic gates for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and so forth.

[0114] In the above description of the present specification, reference to the description of the terms "one embodiment", "another embodiment", or "certain embodiments" or the like means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The illustrative appearances of the above described terms in the specification do not necessarily refer to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0115] Although embodiments of the present application have been shown and described, it would be recognized by those of ordinary skill in the art that various changes, modifications, substitutions, and alterations can be made hereto without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.

[0116] The above is a specific description of the preferred embodiments of the present application, but the present application is not limited to the above-described embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present application, and these equivalent modifications or substitutions are included in the scope defined by the claims of the present application.

Claims

1. A six-degree-of-freedom wireless magnetic positioning system based on soft magnets, characterized in that, include: The magnetic source module, including an electromagnet, is used to generate an alternating magnetic field; A soft magnet is installed at the end of the instrument under test, and the instrument under test and the soft magnet are rigidly connected so that the force and torque on the soft magnet are transmitted to the instrument under test; the soft magnet operates in an alternating magnetic field. A magnetic field detection device, including a magnetic sensor, is used to detect changes in the magnetic field caused by the movement of the soft magnet; The processor measures the pose of the soft magnet based on the detected changes in the magnetic field, obtains the pose of the soft magnet, and calculates the pose of the end effector of the instrument under test based on the pose of the soft magnet. The soft magnet is shaped like an ellipsoid, an elliptical cylinder, or a cuboid, and is asymmetric along its three axes. The measured magnetic field of the magnetized triaxial asymmetric soft magnet is as follows: Wherein, the subscript 's' indicates a magnetic sensor; and 'e' indicates an electromagnet. Indicates a soft magnetic material; This represents a model of the magnetic field intensity distribution of a dipole. This represents the position vector of a soft magnetic body in the world coordinate system. This represents the attitude rotation matrix of a soft magnet; Indicates the demagnetization coefficient of a soft magnetic material; This indicates the magnetic field of the electromagnet detected by the magnetic sensor. (·) represents the magnetic dipole model of a soft magnetic material. (·) represents the magnetic dipole model of an electromagnet. This represents the diagonal matrix of demagnetization coefficients of a soft magnetic material. This represents the rotation matrix from a soft magnetic system to an electromagnetic system. The magnetic moment of an electromagnet is represented by its magnetic moment. This represents the position vector of the electromagnet pointing towards the soft magnetic body. This represents the position vector of the electromagnet pointing towards the magnetic sensor. This represents the position vector of the soft magnet pointing towards the magnetic sensor.

2. The six-degree-of-freedom wireless magnetic positioning system based on soft magnets according to claim 1, characterized in that, The magnetic field detection device also includes a signal processing unit; The magnetic sensor is used to convert magnetic induction intensity into a differential voltage signal; The signal processing unit is used to preprocess the differential voltage signal and output it.

3. A six-degree-of-freedom wireless magnetic positioning system based on soft magnets according to claim 2, characterized in that, The magnetic sensor is a dual-channel triaxial tunnel magnetoresistive sensor.

4. A six-degree-of-freedom wireless magnetic positioning system based on soft magnets according to claim 1, characterized in that, The soft magnet is made of nickel-iron magnetic alloy or nickel-iron amorphous alloy.

5. A six-degree-of-freedom wireless magnetic positioning method based on soft magnets, applied to the system described in any one of claims 1-4, characterized in that, Includes the following steps: Establish a mathematical model relating magnetic field measurements to the pose of a soft magnetic body; Establish a kinematic model of the end effector of the instrument under test; Detecting the changes in the magnetic field caused by the translation and / or rotation of a soft magnetic body in an alternating magnetic field; By combining kinematic and mathematical models to analyze data on magnetic field changes, the pose of the soft magnetic body can be estimated. The position of the end of the instrument under test is calculated based on the position of the soft magnet.

6. The six-degree-of-freedom wireless magnetic positioning method based on soft magnets according to claim 5, characterized in that, The six-degree-of-freedom wireless magnetic positioning method further includes the following steps: Establish a global coordinate system and represent all devices using a unified coordinate system.

7. A six-degree-of-freedom wireless magnetic positioning device based on soft magnets, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method of claim 5 or 6.

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