A position detection system for a surgical instrument

Abstract

The application provides a position detection system of a surgical instrument, comprising a host computer; the host computer is provided with a first sensor and a second sensor arranged at intervals; the surgical instrument can move along the arrangement direction of the first sensor and the second sensor, and is provided with a magnet; the first sensor and the second sensor are arranged in parallel with respective sensitive directions, and can respectively sense the component of the magnetic field of the magnet in the respective sensitive directions; during the movement of the surgical instrument, at least based on the output signals of the first sensor and the second sensor, a position characteristic function is obtained; at least based on the preset mapping relationship between the function value of the position characteristic function and the position of the surgical instrument along the movement direction thereof, the real-time position of the surgical instrument along the movement direction thereof is determined. Accordingly, the position detection precision and efficiency of the surgical instrument can be improved.

Description

Technical Field

[0001] This application relates to position detection technology in medical devices, specifically to a position detection system for surgical instruments that can improve the accuracy and efficiency of position detection. Background Technology

[0002] In medical equipment, electromagnetic coils are often used to drive surgical instruments with permanent magnets (such as the treatment needle, syringe plunger, catheter guidewire, and biopsy needle in a prostate steam therapy device) to achieve precise linear movements. Taking prostate steam therapy surgery as an example, the ejection and retraction of the treatment needle must be precise and reliable; otherwise, it may cause accidental damage to prostate tissue or surrounding tissues. Therefore, high-precision position detection of electromagnetically driven surgical instruments is of great significance.

[0003] In existing technologies, magnetic sensing elements such as magnetoresistive sensors and Hall effect sensors have been widely used for position detection in electromagnetic actuators, linear displacement mechanisms, rotating parts, and magnetic grating / encoding devices. Related solutions typically acquire the change signal from a permanent magnet or external magnetic field source using one or more magnetic sensing elements, and then combine this with calibration curves, lookup tables, linearization algorithms, or compensation algorithms to obtain the displacement or angle information of the measured component.

[0004] Some existing solutions also incorporate redundant sensors, self-calibration circuits, or temperature drift compensation strategies to improve zero-point drift, temperature drift, and sensor consistency issues. While these technologies can achieve a certain level of position detection accuracy under fixed structures, fixed magnets, and repetitive assembly conditions, their technical focus is primarily on sensor signal acquisition, magnetic field compensation, code segmentation, or actuator status feedback, without fully considering the frequent replacement characteristics of disposable medical consumables.

[0005] For scenarios involving replaceable disposable consumables, the magnet performance of different batches of consumables varies significantly, with residual magnetism changing by up to ±20%; the initial position of surgical instruments during each installation has a random deviation, up to ±0.5mm; and changes in ambient temperature cause position sensor sensitivity drift.

[0006] If a single position sensor is used, the output signal will be affected by the coupling of displacement, magnet strength, installation position and temperature drift, making it impossible to uniquely determine the position of the measured part. A tedious calibration (such as mechanical zeroing or user button calibration) must be performed before each operation, which reduces the efficiency of the operation.

[0007] Therefore, improving the accuracy and efficiency of surgical instrument position detection has become a technical challenge in existing technologies. Summary of the Invention

[0008] The purpose of this application is to provide a surgical instrument position detection system that can improve the accuracy and efficiency of surgical instrument position detection. To achieve the above objective, one solution of this application is a surgical instrument position detection system, comprising a reusable main unit used in conjunction with a replaceable surgical instrument; the main unit has a first sensor and a second sensor spaced apart; the surgical instrument is capable of moving along the arrangement direction of the first and second sensors and is equipped with a magnet; the first and second sensors are arranged parallel to each other in their respective sensitive directions and are each capable of sensing the component of the magnetic field of the magnet in its respective sensitive direction; during the movement of the surgical instrument, a position feature function is obtained based at least on the output signals of the first and second sensors; the real-time position of the surgical instrument along its movement direction is determined based at least on a preset mapping relationship between the function value of the position feature function and the position of the surgical instrument along its movement direction.

[0009] In a preferred embodiment, before the surgical instrument begins to move, the initial output signals of the first sensor and the second sensor are acquired, and an initial position feature function is obtained through combination calculation. The initial position of the surgical instrument along its direction of movement is determined according to the mapping relationship. During the movement of the surgical instrument, after determining the real-time position of the surgical instrument along its direction of movement according to the position feature function and the mapping relationship, the relative displacement of the surgical instrument is obtained based on the difference between the real-time position and the initial position.

[0010] In a preferred embodiment, the mapping relationship is obtained through a pre-calibration step, which includes: moving a standard magnet along the movement direction of the surgical instrument to multiple known positions, recording the output signals of the first sensor and the second sensor at each known position, performing combined calculations to obtain the function values ​​of the position feature functions corresponding to each known position, and fitting the mapping relationship.

[0011] In a preferred embodiment, the host computer is further provided with an electromagnetic coil, which, when energized, can drive the magnet and, in turn, drive the surgical instrument to move via the magnet.

[0012] In a preferred embodiment, when performing position detection, a blanking sampling timing sequence is adopted: first, the electromagnetic coil is turned off and a preset blanking time is waited for, and then the output signals of the first sensor and the second sensor are read synchronously.

[0013] In a preferred embodiment, when continuous monitoring of the movement speed of the surgical instrument is required: within a single control cycle, the electromagnetic coil is first turned off and the blanking time is waited for, then the output signals of the first sensor and the second sensor are sampled to obtain the real-time position of the surgical instrument in the current cycle, and then the electromagnetic coil is restored to power; based on the real-time position sequence of the surgical instrument obtained from multiple control cycles, combined with the time interval of the multiple control cycles, the movement speed of the surgical instrument is calculated.

[0014] In a preferred embodiment, the position feature function ρ is obtained by the following combination operation: ρ = [(V1-V 01 ) / (V2- V 02 )]·(S2 / S1), where V1 and V2 are the output voltages of the first sensor and the second sensor, respectively, V 01 V 02 S1 and S2 are the zero-point bias voltages of the first sensor and the second sensor, respectively, and the sensitivities of the first sensor and the second sensor, respectively.

[0015] In a preferred embodiment, the sensing directions of the first sensor and the second sensor intersect with the direction of movement of the surgical instrument.

[0016] In a preferred embodiment, when the output signals of the first sensor and the second sensor are simultaneously close to their respective zero-point bias voltages, and the position characteristic function deviates from the range calibrated in the pre-calibration step, it is determined that the magnet has detached.

[0017] In a preferred embodiment, if the difference between the output signals of the first sensor and the second sensor exceeds a predetermined threshold during the movement of the surgical instrument, it is determined to be a sensor malfunction.

[0018] In a preferred embodiment, if the position feature function still fails to reach the value corresponding to the target position after the electromagnetic coil has been energized for a preset maximum duration, and the position feature function remains unchanged for a specified duration, it is determined to be mechanical jamming.

[0019] In a preferred embodiment, when the electromagnetic coil is de-energized, the position characteristic function first reaches the value corresponding to the target position, and then oscillates and remains in a certain range below that value, at which point it is determined that the position rebound or withdrawal has failed.

[0020] In a preferred embodiment, the magnetic moment direction of the magnet is parallel to the direction of motion of the surgical instrument.

[0021] The surgical instrument position detection system of the above embodiments of this application, by setting two sensors and constructing a position feature function that is independent of the applied magnetic field strength and temperature drift, and combining it with a preset mapping relationship, can achieve high-precision, calibration-free position detection of surgical instruments, which greatly improves surgical efficiency and safety. Attached Figure Description

[0022] To more clearly illustrate this application, the accompanying drawings will be described and explained below. Obviously, the drawings described below only illustrate certain aspects of some exemplary embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of an example surgical instrument position detection system.

[0024] Figure 2 The curves illustrate how the output voltage of the first and second sensors changes with the position of the surgical instrument along its direction of motion.

[0025] Figure 3 This is a graph illustrating the mapping relationship between the function value of the positional characteristic function and the position of the surgical instrument along its direction of movement.

[0026] Figure 4 This is an example of a blanking sampling timing diagram.

[0027] Figure 5 This is an example of a comparison curve showing the detection results of the proposed solution and a single-sensor solution under varying magnet strength conditions.

[0028] Attached image caption:

[0029] 1. Host

[0030] 10 processors

[0031] 11 First Sensor

[0032] 12 Second Sensor

[0033] 13 Electromagnetic coil

[0034] 151 First host card connector

[0035] 161 Second host card connector

[0036] 2 Surgical instruments

[0037] 20 Slides

[0038] 21 Magnets

[0039] 22 Instrument housing

[0040] 251 First Instrument Connector

[0041] 261 Second Instrument Connector Detailed Implementation

[0042] Various exemplary embodiments of this application are described in detail below with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the application or its application or use. This application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the application thorough and complete, and to fully express the scope of the application to those skilled in the art. It should be noted that, unless otherwise stated, the relative arrangement of components and steps, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0043] As used in this application, the words “including” or “comprising” or similar terms mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility that it may also cover other elements.

[0044] All terms used in this application (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as being interpreted with idealized or highly formalized meanings, unless explicitly defined herein.

[0045] For components, specific model numbers and other parameters of components not described in detail in this section, the interrelationships between components and control circuits, these may be considered as techniques, methods and devices known to those skilled in the art, but where appropriate, such techniques, methods and devices should be considered part of the specification.

[0046] It should be noted that although the operations of the method described in this application are given a specific order, this does not require or imply that these operations must be performed in that specific order, or that all of the operations shown must be performed to achieve the desired result. On the contrary, the steps described in this application may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0047] The following is for reference Figure 1-5 This application describes the composition of the surgical instrument position detection system. Figure 1 This is a schematic diagram of the overall structure of the surgical instrument position detection system. Figure 2The curves show the changes in the output voltage of the first sensor 11 and the second sensor 12 as a function of the position of the surgical instrument 2 along its direction of movement. Figure 3 It is a graph showing the mapping relationship between the function value of the position characteristic function and the position of surgical instrument 2 along its direction of movement. Figure 4 This is a timing diagram of the blanking sampling. Figure 5 This is a comparison curve of the detection results of the proposed solution and the single-sensor solution under varying magnet strength conditions.

[0048] In electromagnetically driven medical devices, precise control of the position of surgical instruments 2 with permanent magnets (such as the treatment needle, syringe plunger, catheter guidewire, biopsy needle, etc. in a steam therapy device) is crucial for surgical success. Taking prostate steam therapy as an example, the ejection depth of the treatment needle must be accurate to the millimeter level; otherwise, it may damage surrounding healthy tissue.

[0049] However, in clinical practice using disposable consumables, the remanent magnet strength of the built-in permanent magnets in different batches of disposable consumables may vary by as much as ±20%. Furthermore, the initial position of the movable parts (surgical instruments 2) cannot be guaranteed to be completely consistent each time medical staff install the disposable consumables onto the equipment, potentially resulting in random deviations of up to ±0.5mm. Combined with changes in the operating room temperature and the heat generated by the equipment itself, this can cause sensor sensitivity and zero-point drift, further increasing measurement errors.

[0050] In existing technologies, single-sensor solutions cannot efficiently distinguish the effects of displacement changes, magnet strength changes, and installation position deviations on the output signal. Each time consumables are replaced, a tedious mechanical zeroing or calibration must be performed, which not only interrupts the surgical procedure and prolongs the patient's anesthesia time, but also brings additional infection risks.

[0051] To address the aforementioned challenges, this invention provides a surgical instrument position detection system that uses two sensors and related algorithms to extract pure position information from the sensor output, independent of magnet strength and temperature drift, thereby achieving plug-and-play calibration-free detection.

[0052] like Figure 1 As shown, the system includes a reusable host 1, which is used in conjunction with replaceable surgical instruments 2. The host 1 is equipped with a first sensor 11 and a second sensor 12. For example, the first sensor 11 and the second sensor 12 are both TMR (tunneling magnetoresistive) sensors. The first sensor 11 and the second sensor 12 are arranged at intervals, for example, the first sensor 11 and the second sensor 12 are fixed on the PCB board inside the host 1 with a 10mm interval.

[0053] For ease of explanation, Figure 1The first sensor 11 and the second sensor 12 shown are arranged in a horizontal or axial direction. The direction perpendicular to the horizontal direction is the vertical or radial direction. In the horizontal direction, the direction from the second sensor 12 toward the first sensor 11 is considered front, and the opposite direction is considered back. In the vertical direction, the direction from the host 1 toward the surgical instrument 2 is considered up, and the opposite direction is considered down.

[0054] In this application, the surgical instrument 2 is configured to reciprocate along the horizontal direction, i.e., the arrangement direction of the first sensor 11 and the second sensor 12. Preferably, the sensing directions of the first sensor 11 and the second sensor 12 are parallel to each other. More preferably, the sensing directions of the first sensor 11 and the second sensor 12 are arranged intersecting the movement direction of the surgical instrument 2. Even more preferably, the sensing directions of the first sensor 11 and the second sensor 12 are both perpendicular to the movement direction of the surgical instrument 2, so as to more accurately sense the magnetic field changes of the magnet 21 in that direction.

[0055] To illustrate the sensitive direction, we'll use a TMR sensor as an example. It's a high-sensitivity magnetic field sensor that utilizes the magnetic tunnel junction effect. Its physical basis is that the resistance of a TMR element strongly depends on the angle between the magnetization directions of the pinned layers and the free layers. Typically, the pinned layers are fixed in a certain direction (e.g., the X-axis of the chip). Only when an external magnetic field has a component in this fixed direction will the relative angle between the two layers change significantly, causing a change in resistance, which in turn leads to a change in the sensor's output signal, such as the output voltage. Most linear TMR sensors are uniaxially sensitive, meaning they are only sensitive to magnetic field components parallel to the sensor chip surface and along a specific axis (e.g., the X-axis). This specific axis direction is the sensitive direction. Magnetic field components perpendicular to it (e.g., the Z-axis or Y-axis) produce virtually no response. In other words, the sensitive direction is the direction in which the sensor itself is most sensitive to external magnetic fields. When using it, it's preferable to align the sensitive direction with the direction of the magnetic field to be measured to obtain the maximum output.

[0056] It should be noted that the first sensor 11 and the second sensor 12 in this application are not limited to the TMR sensor in the example, nor are they limited to operating in the linear region. Any magnetically sensitive element that has repeatable, monotonic output characteristics and can sense changes in the component of the magnetic field in its sensitive direction (such as, but not limited to, Hall sensors, anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, etc.) can be used as the sensor in this application.

[0057] As an example, the processor 10 in this application uses an STM32G4 series microcontroller for algorithm calculation and control, and the specific use is not limited.

[0058] Continue reading Figure 1The surgical instrument 2 is connected to a magnet 21, which serves as a permanent magnet. Exemplarily, the magnet 21 is an axially magnetized neodymium iron boron magnet (e.g., 4 mm in diameter and 2 mm in thickness). The surgical instrument 2 is at least partially located within the instrument housing 22. During operation, the front end of the surgical instrument 2 extends forward out of the instrument housing 22, and the instrument housing 22 has a groove 20 for the movement of the surgical instrument 2. Preferably, the magnet 21 is bonded to the rear side of the surgical instrument 2, and its magnetic moment direction is parallel to the direction of movement of the surgical instrument 2. In this embodiment, the surgical instrument 2, the instrument housing 22, and the magnet 21 are pre-assembled together for use as the aforementioned disposable consumables, while the main unit 1 serves as a reusable device.

[0059] The main unit 1 is also equipped with an electromagnetic coil 13. For example, in the assembled state, the electromagnetic coil 13 is located behind the magnet 21. When energized, it can drive the magnet 21 and then drive the surgical instrument 2 to move in the horizontal direction via the magnet 21.

[0060] like Figure 1 As shown, the instrument housing 22 has a first instrument latching part 251 located on the front side and a second instrument latching part 261 located on the rear side. The main unit 1 has a first main unit latching part 151 located on the front side and a second main unit latching part 161 located on the rear side. For example, in use, the instrument housing 22 is installed in the corresponding position on the main unit 1, so that the first instrument latching part 251 latches with the first main unit latching part 151. Then, the second main unit latching part 161 is pressed forward to latch with the second instrument latching part 261, thus achieving assembly between the main unit 1 and the surgical instrument 2. When it is necessary to replace the surgical instrument 2, simply pry the second main unit latching part 161 backward to separate it from the second instrument latching part 261, and the instrument housing 22 and the surgical instrument 2 inside can be easily disassembled.

[0061] Next, the principle of the location detection in this application will be explained.

[0062] As an example, the horizontal direction is taken as the x-axis, which extends from back to front, and the vertical direction is taken as the y-axis, which extends from bottom to top. The origin of the xy-axis coordinate system is located behind the first sensor 11. Let the first sensor 11 be located at x1 = p1, and the second sensor 12 be located at x2 = p2, where p1 < p2.

[0063] Neglecting radial installation deviation and attitude deviation of magnet 21 (whose magnetic moment is strictly along the x-axis), assume that the geometric center of magnet 21 in the horizontal direction is located at x. n The magnetic moment is m (unit: A·m²). The first sensor 11 and the second sensor 12 operate in the linear region, and their respective output signals are proportional to the magnetic field component along their sensitive direction. In this embodiment, the output signals of the two sensors are taken as voltages, then:

[0064] V i =V0i +S i ·(B⊥,i(x n )) (1)

[0065] Where: i = 1 or 2, corresponding to the first sensor 11 and the second sensor 12 respectively; V i V is the output voltage of the i-th sensor, in V. 0i It is the zero-point bias voltage of the i-th sensor, i.e., the non-zero voltage output when there is no external magnetic field, in V; S i This is the sensitivity of the i-th sensor, in V / T; B⊥,i(x n ) represents the vertical magnetic field component generated by magnet 21 at the i-th sensor, with units of T; x n is the position of the geometric center of magnet 21 in the horizontal direction along the x-axis; m is the magnitude of the magnetic moment of magnet 21, in A·m².

[0066] Since the vertical magnetic field components at the sensor are proportional to the magnitude m of the magnetic moment of magnet 21, they can be expressed as: B⊥,i(x n )=m·bi(x n (2)

[0067] Where bi(x) n Let represent the vertical magnetic field component generated by magnet 21 at the i-th sensor under unit magnetic moment (m=1). This function is determined by the spatial arrangement of the sensor and magnet 21, and within the effective measurement range, it is a single-valued function that varies with the horizontal position of magnet 21. Substituting equation (2) into equation (1), we get:

[0068] V i =V 0i +S i ·m·b i (x n (3)

[0069] Expand on the first sensor 11 and the second sensor 12 respectively:

[0070] V1 = V 01 +S1·m·b1(x n (4)

[0071] V2 = V 02 +S2·m·b2(x n (5)

[0072] Because the zero-point bias voltage is superimposed on the effective output signal when detecting weak magnetic fields, it introduces a fixed error in the output signal and may even cause amplifier saturation. Therefore, the output signals of the two sensors are first zero-point subtracted to obtain their respective relative amplitudes of output voltage.

[0073] ΔV1=V1-V 01 (6)

[0074] ΔV2=V2-V 02 (7)

[0075] Combining equations (4) and (5), we can obtain:

[0076] ΔV1=S1·m·b1(x n (8)

[0077] ΔV2=S2·m·b2(x n (9)

[0078] See Figure 2 In the figure, the horizontal axis represents the position of magnet 21 on the x-axis, and the vertical axis represents the voltage output by the sensor after deducting the zero-point bias voltage (ΔV). i In the figure, the solid line represents the output voltage curve of the first sensor 11, and the dashed line represents the output voltage curve of the second sensor 12. It can be seen that the closer the magnet 21 is to the sensor's mounting position (e.g., the first sensor 11 is x1 = 2 mm, and the second sensor 12 is x2 = 10 mm), the larger the magnetic field component of the magnet 21 detected by these two sensors in the sensitive direction. This indicates that the closer the magnet 21 is to the sensor's mounting position, the greater the magnetic field component detected by the two sensors in the sensitive direction. n b2(x) n The larger it is.

[0079] According to equations (8) and (9), we can obtain: ΔV1 / ΔV2=(S1 / S2)·(b1(x) n ) / b2(x n The ΔV1 / ΔV2 ratio eliminates the influence of the magnetic moment m of magnet 21, but still contains the sensor sensitivity ratio S1 / S2. Different sensors may have different sensitivities due to factors such as manufacturing tolerances and temperature drift. If this ratio is directly used to calculate the position of the geometric center of magnet 21, then replacing the host unit 1 or a temperature change will alter S1 / S2, causing the mapping relationship to fail.

[0080] To eliminate the influence of sensor sensitivity differences, we multiply ΔV1 / ΔV2 by S2 / S1, defining the position characteristic function ρ as follows:

[0081] ρ=[(V1-V 01 ) / (V2-V 02 )]·(S2 / S1) (10)

[0082] That is: ρ=(ΔV1 / ΔV2)·(S2 / S1) (11)

[0083] Substituting equations (8) and (9) into equation (11), we get:

[0084] ρ=[S1·m·b1(x n )] / [S2·m·b2(x n )]·(S2 / S1) (12)

[0085] After simplification, we get: ρ=b1(x n ) / b2(x n (13)

[0086] As can be seen from equation (13), the position characteristic function ρ is related to the magnitude of the magnetic moment m of magnet 21 and the sensor sensitivity S. i And the relative amplitude ΔV of the output voltage of each sensor after deducting the zero-point bias voltage. i It is irrelevant and depends only on the horizontal geometric center position x of magnet 21. n Within the effective measurement range (e.g., when the geometric center of magnet 21 is located between p1 and p2), the function b1(x) n ) / b2(x n ) is a strictly monotonic function.

[0087] In actual operations, we do not directly measure b1(x) n ) / b2(x n Instead of directly measuring the output voltages of the first sensor 11 and the second sensor 12, we subtract their respective zero-point bias voltages to obtain the ratio ΔV1 / ΔV2 of the relative amplitudes of the output voltages. Then, we substitute this ratio with pre-calibrated sensitivity constants S1 and S2 (measured and stored at the factory for each device) to calculate the position characteristic function ρ. Therefore, acquiring the output voltages of the two sensors is only an intermediate step; ultimately, we obtain the position characteristic function ρ after eliminating sensor differences. This process is equivalent to converting the voltage quantity into a physical quantity independent of the sensors.

[0088] It is understandable that, since magnet 21 is fixedly connected to surgical instrument 2, the geometric center position x of magnet 21 is... n There is a fixed geometric offset between the surgical instrument 2 and a specific reference point (e.g., its front or rear end). Therefore, x is known. n This is equivalent to uniquely determining the position of surgical instrument 2 along its direction of motion. In other words, there is a one-to-one and strictly monotonic mapping relationship between the function value of the position characteristic function ρ and the position of surgical instrument 2 along its direction of motion, specifically as follows: Figure 3 As shown in the figure, the horizontal axis represents the position of surgical instrument 2 on the x-axis, and the vertical axis represents the position characteristic function ρ.

[0089] As a preferred approach, the mapping relationship is obtained through a pre-calibration step. The core of this step is to simulate the movement of a standard surgical instrument 2 (or a standard magnet mounted on it) in an actual device using a high-precision measuring device (such as a precision stepping slide). Specifically, the standard magnet (or the surgical instrument 2 with the standard magnet) is moved along the x-axis to multiple precisely known positions x. n(j) j = 0, 1, 2, 3, ... Record the output voltage V of the first sensor 11 and the second sensor 12 at each known location. 1(j) and V 2(j) Then calculate the function value ρ of the positional characteristic function corresponding to that position. (j) Thus, a series of data point pairs (ρ) are obtained. (j) ,x n(j) ).

[0090] Because b1(x) n ) / b2(x n ) is a monotonic function within the effective measurement range, therefore ρ and x n It is also a one-to-one correspondence. The mapping relationship can be established by polynomial fitting or table lookup, for example, a cubic polynomial: x = a0 + a1ρ + a2ρ² + a3ρ³, and the coefficients a0, a1, a2, and a3 can be stored in an E²PROM.

[0091] It should be noted that when surgical instrument 2 is replaced, its initial position on the x-axis is unknown. However, this system does not need to know this initial position in advance. Specifically, before the electromagnetic coil 13 is energized, surgical instrument 2 has not yet started to move, and the processor 10 reads the initial output voltage V of the first sensor 11 and the second sensor 12. 1(0) V 2(0) Calculate the initial position characteristic function based on the initial output voltage:

[0092] ρ0=[(V 1(0) -V 01 ) / (V 2(0) -V 02 )]·(S2 / S1) (15)

[0093] Then, based on the mapping relationship, the initial position of the surgical instrument 2 on the x-axis is obtained.

[0094] During subsequent detection (during motion), the output voltages V1 and V2 of the first sensor 11 and the second sensor 12 are sampled in real time, and the real-time position feature function is calculated:

[0095] ρ=[(V1-V 01 ) / (V2-V 02 )]·(S2 / S1) (16)

[0096] Then, based on the mapping relationship, the real-time position of surgical instrument 2 on the x-axis is obtained. Subtracting the initial position from this real-time position yields the relative displacement Δx of surgical instrument 2, i.e., its actual travel.

[0097] Therefore, even if there is a deviation in the initial position of the surgical instrument 2 on the x-axis each time consumables are replaced, this application can still automatically obtain the initial installation position through the initial position characteristic function, and use the relative displacement of the surgical instrument 2, i.e. the actual stroke, as the basis for surgical control and judgment. The whole process is plug-and-play and requires no user calibration.

[0098] Next, combined Figure 4 Explanation of blanking sampling.

[0099] When electromagnetic coil 13 is energized, it generates a strong magnetic field, which can cause the TMR sensor to enter the saturation region. Therefore, preferably, when performing position detection, a blanking sampling sequence is adopted: first, electromagnetic coil 13 is turned off and waits for a preset blanking time t_blank, such as... Figure 4 The pulse diagram in the upper side figure illustrates that sampling is then triggered to synchronously read the output signals, i.e., the output voltage, from the first sensor 11 and the second sensor 12, as shown below. Figure 4 The pulse diagram in the lower figure illustrates this. This avoids the influence of the magnetic field generated by electromagnetic coil 13 on the sampling results. Figure 4 The upper and lower diagrams share a common time axis. The vertical axis of the upper diagram represents the current or voltage of the electromagnetic coil 13, while the vertical axis of the lower diagram represents the sampling trigger.

[0100] For example, the blanking time is set according to the time constant of the electromagnetic coil 13, with a typical value of 50μs-200μs; the typical value of the sampling time t_sample for reading the output voltages of the two sensors is 10μs. More preferably, after one blanking time t_blank, multiple samples can be taken and the average value of the output voltage of the first sensor 11 and the average value of the output voltage of the second sensor 12 can be taken to obtain the current sampled values ​​V1 and V2.

[0101] Further preferably, for scenarios requiring real-time monitoring of the movement speed of the surgical instrument 2, a short-time power-off sampling method can be used: within a single control cycle, the electromagnetic coil 13 is first turned off, and after waiting for the blanking time, the output voltages of the first sensor 11 and the second sensor 12 are sampled to obtain the real-time position of the surgical instrument 2 on the x-axis within the current cycle. Then, the electromagnetic coil is powered on again. Based on the real-time position sequence of the surgical instrument 2 obtained from multiple control cycles, combined with the time interval of these multiple control cycles, the movement speed of the surgical instrument 2 is calculated. Preferably, these multiple control cycles are continuous control cycles.

[0102] For example, within a single control cycle of 1ms, the electromagnetic coil 13 is turned off and a blanking time of 50μs is waited. The first sensor 11 and the second sensor 12 are sampled, and the actual position of the surgical instrument 2 on the x-axis is obtained according to the mapping relationship. Then, the electromagnetic coil 13 is energized again. This process is repeated for several consecutive control cycles. Based on the time interval of these control cycles and the stroke of the surgical instrument 2, the movement speed of the surgical instrument 2 is calculated without significantly affecting the driving force on the magnet 21.

[0103] Next, the fault diagnosis will be explained.

[0104] In this embodiment, the consistency and redundancy of the output voltages of the first sensor 11 and the second sensor 12 can be used to diagnose a variety of abnormalities.

[0105] For example, when the output signals of the first sensor 11 and the second sensor 12 simultaneously approach their respective zero-point bias voltages, and the position characteristic function exceeds the range calibrated in the pre-calibration step, it is determined that the magnet 21 has detached. At this time, the surgical instrument 2 cannot be driven, the system alarms, and triggering is prohibited.

[0106] During the movement of surgical instrument 2, if the output signals (e.g., output voltages) of the first sensor 11 and the second sensor 12 differ by more than a specified threshold, a sensor malfunction is determined. In this case, the collected sensor output data is unreliable, and the system alarms to prompt for repair.

[0107] If, after the electromagnetic coil 13 has been energized for the preset maximum duration, the position characteristic function still has not reached the value corresponding to the target position, and the position characteristic function remains unchanged for the specified duration, it is determined to be mechanical jamming, and the system will power off and alarm. The target position here is the position corresponding to the maximum forward stroke of the surgical instrument 2.

[0108] When the electromagnetic coil 13 is de-energized, the position characteristic function first reaches the value corresponding to the target position, and then oscillates and remains in a certain range below the value. This is determined to be a failure of the surgical instrument 2 to return to its position or retract. When the surgical instrument 2 is stuck before it is fully extended or retracted, the system alarms.

[0109] For example, after a certain drive, if V1≈0mV and V2≈50mV are detected (while normally both are tens of mV), and the position characteristic function ρ deviates significantly from the range calibrated in the pre-calibration steps, the system determines that the magnet has fallen off, prompts for replacement of consumables, and prohibits the electromagnetic coil 13 from being energized again. As another example, if the position characteristic function ρ remains unchanged near its initial value after the electromagnetic coil 13 has been energized for the maximum duration (e.g., 300ms), it is determined to be mechanical jamming, the system cuts off the drive power and issues a red alarm.

[0110] Next, specific embodiments will be described.

[0111] In Example 1, the surgical instrument 2 is a treatment needle of a hot steam therapy device. The first sensor 11 and the second sensor 12 are exemplarily both TMR sensors, spaced 10mm apart horizontally, fixed to a PCB board inside the main unit 1, with their sensing directions perpendicular to the horizontal direction. The processor 10 uses an STM32 series microcontroller.

[0112] In the pre-calibration step, a standard treatment needle (with a standard magnet) is clamped on a precision stepping slide (slide accuracy 0.01mm), and the standard treatment needle is moved from x=0 to x=12mm in 0.2mm steps, with V1 and V2 recorded at each position; the positional characteristic function corresponding to each step is calculated: ρ = [(V1 - V2) / V2] 01 ) / (V2-V 02 )]·(S2 / S1), where V 01 V 02 S1 and S2 can be obtained from the sensor datasheet or through dark-field measurements. Then, a function representing the mapping relationship is fitted, for example, a cubic polynomial: x = a0 + a1ρ + a2ρ² + a3ρ³, and the coefficients a0, a1, a2, and a3 are stored in an E²PROM.

[0113] When a new treatment needle needs to be installed, the operator inserts the treatment needle into the main unit 1 and secures it. The device automatically detects the new treatment needle (via a microswitch or sensor abrupt change) and immediately reads the initial output voltage V of the first sensor 11 and the second sensor 12. 1(0) V 2(0) Calculate the initial position characteristic function: ρ0=[(V 1(0) -V 01 ) / (V 2(0) -V 02 )]·(S2 / S1), and obtain the initial position of the surgical instrument 2 on the x-axis according to the mapping relationship, and the device displays "Ready".

[0114] During treatment, under ultrasound guidance, the operator aligns the tip of the treatment needle with the target tissue, turns on the switch, and the processor 10 controls the electromagnetic coil 13 to be energized (e.g., 24V, 300ms pulse). Then, according to the blanking sampling sequence (after the electromagnetic coil 13 is de-energized, a blanking time of 80μs is waited), the real-time outputs V1 and V2 are read, and the real-time positional feature function is calculated: ρ=[(V1-V 01 ) / (V2-V 02 The real-time position of the surgical instrument 2 on the x-axis is obtained by subtracting the initial position from the real-time position. The relative displacement Δx of the treatment needle, i.e., the actual stroke, is then obtained.

[0115] This system can also perform positioning judgment and safety protection: if Δx reaches within ±0.1mm of the target value (e.g., 10mm), the device indicator light turns green and the coil is automatically de-energized; if Δx remains unchanged for a long time and does not reach the target value, it is determined that the surgical instrument 2 is stuck, the device alarms red and cuts off the drive power; when it is necessary to withdraw, the electromagnetic coil 13 is energized in reverse, so that the treatment needle returns to the initial position (Δx=0).

[0116] In Example 2, the surgical instrument 2 is the piston rod of a medical syringe. The first sensor 11 and the second sensor 12 are exemplary TMR sensors, spaced 10mm apart horizontally and fixed to a PCB board inside the host unit 1. The sensing directions of the two sensors are perpendicular to the horizontal direction. The processor 10 uses an STM32 series. A circular neodymium iron boron magnet (5mm in diameter, 2mm thick, axially magnetized) is bonded to the end of the syringe piston rod.

[0117] The pre-calibration steps are the same as in Example 1: A standard syringe is clamped onto a precision stepping slide and moved from the initial position (x = 0) to the endpoint (x = 12 mm) in 0.2 mm steps. The output voltages V1 and V2 of the first sensor 11 and the second sensor 12 are recorded at each step position. The position characteristic function ρ = [(V1 - V2)] is calculated. 01 ) / (V2-V 02 )]·(S2 / S1), where V 01 V 02 S1 and S2 can be obtained from the sensor datasheet or through dark-field measurements. Then, a function (e.g., a cubic polynomial) is fitted to obtain the mapping relationship: x = a0 + a1ρ + a2ρ² + a3ρ³, and the coefficients a0, a1, a2, and a3 are stored in an E²PROM.

[0118] User procedure: After inserting a new syringe, the device automatically reads the initial output voltage V of the first sensor 11 and the second sensor 12. 1(0) V 2(0) Calculate the initial position characteristic function: ρ0=[(V 1(0) -V 01 ) / (V 2(0) -V 02 The initial position of the surgical instrument 2 on the x-axis is obtained according to the mapping relationship, and the device displays "Ready". Then, the processor 10 controls the electromagnetic coil 13 to be energized (e.g., 24V, 300ms pulse); after the electromagnetic coil 13 is de-energized, a blanking time of 80μs is waited, and the real-time output voltages V1 and V2 of the first sensor 11 and the second sensor 12 are read. The real-time position feature function ρ = [(V1-V2) / (V2 ... 01 ) / (V2-V 02The real-time position of the surgical instrument 2 on the x-axis is obtained according to the mapping relationship. The relative displacement Δx, i.e., the actual stroke of the piston rod, is obtained by subtracting the initial position from the real-time position. If Δx is within ±0.1mm of the target value (e.g., 8mm), the device indicator light is green; otherwise, a red alarm is triggered, indicating jamming or weak magnetism of magnet 21.

[0119] In addition, surgical instrument 2 can also be a catheter / guidewire with dynamic tracking, or other instruments that require precise detection or control of their movement position, which will not be repeated here. For scenarios requiring real-time monitoring of movement speed (such as the continuous pushing process of the catheter or guidewire), the aforementioned short-term power-off sampling method is used. This method can obtain continuous movement trajectories without significantly affecting the driving force, and is suitable for interventional surgical scenarios with high real-time requirements.

[0120] Next, combined Figure 5 The technical effects of this application will be explained.

[0121] like Figure 5 As shown in the figure, the horizontal axis represents the actual position of surgical instrument 2 in the direction of movement, and the vertical axis represents the detection result. The solid black line in the figure represents the ideal output corresponding to the actual position of surgical instrument 2 on the x-axis. Dashed line A represents the detection result of the dual-sensor scheme of this application for the position of surgical instrument 2 on the x-axis; this detection result is independent of the deviation in the magnitude of the magnetic moment of magnet 21 and the error in the initial installation position. Dashed line B represents the single-sensor scheme, where the magnetic moment of magnet 21 is 0.8 (A·m). 2 The detection results of surgical instrument 2 in the x-axis position with initial installation position error are shown. The dashed line C represents the single-sensor scheme, and the magnetic moment of magnet 21 is 1.0 (A·m). 2 The detection results of surgical instrument 2 in the x-axis position with initial installation position error are shown. The dashed line D represents the single-sensor scheme, and the magnetic moment of magnet 21 is 1.2 (A·m). 2 And the detection results of the surgical instrument 2 in the x-axis position with initial installation position error. From Figure 5 As can be seen, the detection results of the dual-sensor scheme in this application are closer to the ideal output, while the detection results of the single-sensor scheme have a larger deviation, and the detection results are greatly affected by the change of the magnetic moment of the magnet 21 and the error of the initial installation position.

[0122] It is understood that this application constructs a magnetic field strength (m) and sensor sensitivity (S) related to magnet 21. iThe device automatically obtains the initial position as a reference zero point by using the independent position characteristic function ρ and the initial position characteristic function ρ0, thus completely eliminating the influence of performance differences (up to ±20%) between different batches of consumable magnets 21 and random deviations (up to ±0.5mm) in each installation position. In clinical operation, after personnel change surgical instruments 2, no zeroing, calibration, or software settings are required; the device can automatically recognize and start working, simplifying the surgical procedure and reducing the risks associated with additional operations.

[0123] The position characteristic function of this application not only eliminates individual differences in magnet 21, but also eliminates zero-point and sensitivity drift caused by changes in ambient temperature and temperature drift of the sensor itself. Experimental data shows that the position detection resolution of this system can reach 0.05mm, enabling precise control of key parameters such as the ejection depth of hot steam therapy needles and the dosage of medication administered by syringes. Simultaneously, the synchronous sampling and combined calculation method of the two sensors reduces the influence of noise such as electromagnetic interference, ensuring the stability of the system.

[0124] Meanwhile, this application employs a redundant configuration of two sensors, enabling the system to monitor its operational status in real time. By analyzing the consistency of the output signals from the two sensors, the relative amplitude of the output voltage, and the variation patterns of the position characteristic function, various abnormalities such as magnet detachment, single sensor failure, and mechanical jamming can be effectively diagnosed, improving the safety of equipment use. This is crucial for surgeries with extremely high reliability requirements, such as prostate steam therapy.

[0125] Furthermore, the installation tolerances of the sensor, magnet 21, and electromagnetic coil 13, as well as the sensitivity differences of the sensor, can all be absorbed through a one-time calibration at the factory. The calibration process only requires a high-precision slide table and standard tooling to establish the mapping function and burn the coefficients into the memory of each host 1. This allows for a more relaxed requirement for the machining and assembly accuracy of the host 1, reducing manufacturing costs. For large quantities of disposable consumables, since the differences in magnet performance have been eliminated by the position characteristic function, there is no need for expensive screening or matching, further reducing consumable costs.

[0126] In summary, this application effectively solves the problem of position detection in the context of replaceable medical consumables, and has good technical effects in terms of accuracy, convenience and safety.

[0127] It should be understood that the specific embodiments described above are only used to explain this application, and the scope of protection of this application is not limited thereto. Any changes, substitutions, or combinations made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be covered within the scope of protection of this application.

Claims

1. A surgical instrument position detection system, characterized in that: Includes a reusable main unit, which is used in conjunction with replaceable surgical instruments; The host computer has a first sensor and a second sensor arranged at intervals; The surgical instrument is capable of moving along the arrangement direction of the first sensor and the second sensor, and is equipped with a magnet; The first sensor and the second sensor are arranged in a manner that their respective sensitive directions are parallel to each other, and each sensor is capable of sensing the component of the magnetic field of the magnet in its respective sensitive direction. During the movement of the surgical instrument, a position feature function is obtained based at least on the output signals of the first and second sensors; The real-time position of the surgical instrument along its direction of motion is determined based at least on a preset mapping relationship between the function value of the position feature function and the position of the surgical instrument along its direction of motion. Specifically, the output signals of the first sensor and the second sensor are obtained when the reference magnet is at multiple known positions along the movement direction of the surgical instrument, and the mapping relationship is established based at least on the multiple known positions and the corresponding output signals of the first sensor and the second sensor; The positional feature function ρ is obtained through the following combination operation: ρ=[(V1-V 01 ) / (V2-V 02 )]·(S2 / S1), Where V1 and V2 are the output voltages of the first sensor and the second sensor, respectively, V 01 V 02 S1 and S2 are the zero-point bias voltages of the first sensor and the second sensor, respectively, and the sensitivities of the first sensor and the second sensor, respectively.

2. The surgical instrument position detection system according to claim 1, characterized in that: The position detection system is also used to: acquire the initial output signals of the first sensor and the second sensor before the surgical instrument begins to move, obtain the initial position feature function through combination calculation, and determine the initial position of the surgical instrument along its direction of movement according to the mapping relationship; During the movement of the surgical instrument, after determining the real-time position of the surgical instrument along its direction of movement based on the position feature function and the mapping relationship, the relative displacement of the surgical instrument is obtained based on the difference between the real-time position and the initial position.

3. The surgical instrument position detection system according to claim 1, characterized in that: The mapping relationship is obtained through a pre-calibration step, which includes: The standard magnet is moved to multiple known positions along the direction of movement of the surgical instrument. The output signals of the first sensor and the second sensor at each known position are recorded. The function values ​​of the position feature function corresponding to each known position are obtained through combination calculation, and the mapping relationship is obtained by fitting.

4. The surgical instrument position detection system according to claim 1, characterized in that: The host is also equipped with an electromagnetic coil, which can drive the magnet when energized, and then drive the surgical instrument to move via the magnet.

5. The surgical instrument position detection system according to claim 4, characterized in that: When performing position detection, the blanking sampling timing is used: First, the electromagnetic coil is turned off and a preset blanking time is waited for. Then, the output signals of the first sensor and the second sensor are read synchronously.

6. The surgical instrument position detection system according to claim 5, characterized in that: When it is necessary to continuously monitor the movement speed of the surgical instruments: Within a single control cycle, the electromagnetic coil is first turned off and the blanking time is waited for. Then, the output signals of the first sensor and the second sensor are sampled to obtain the real-time position of the surgical instrument in the current cycle. Then, the electromagnetic coil is powered on again. The movement speed of the surgical instrument is calculated based on the real-time position sequence of the surgical instrument obtained from multiple control cycles and the time interval of these multiple control cycles.

7. The surgical instrument position detection system according to any one of claims 1-6, characterized in that: The sensing directions of the first sensor and the second sensor intersect with the movement direction of the surgical instrument.

8. The surgical instrument position detection system according to claim 3, characterized in that: When the output signals of the first sensor and the second sensor are simultaneously close to their respective zero-point bias voltages, and the position characteristic function deviates from the range calibrated in the pre-calibration step, it is determined that the magnet has fallen off.

9. The surgical instrument position detection system according to any one of claims 1-6, characterized in that: If the difference between the output signals of the first sensor and the second sensor exceeds a predetermined threshold during the movement of the surgical instrument, it is determined to be a sensor malfunction.

10. The surgical instrument position detection system according to any one of claims 4-6, characterized in that: If the position feature function fails to reach the value corresponding to the target position after the electromagnetic coil has been energized for a preset maximum duration, and the position feature function remains unchanged for a specified duration, it is determined to be mechanical jamming.

11. The surgical instrument position detection system according to claim 10, characterized in that: When the electromagnetic coil is de-energized, the position characteristic function first reaches the value corresponding to the target position, and then oscillates and remains in a certain range below the value. This is then determined to be a failure to reach the target position or a failure to retract.

12. The surgical instrument position detection system according to any one of claims 1-6, characterized in that: The magnetic moment direction of the magnet is parallel to the direction of motion of the surgical instrument.

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