A force feedback dynamic calibration system and method for a labial gland biopsy needle

Abstract

This invention discloses a dynamic calibration system and method for force feedback of a labial gland biopsy needle, relating to the field of medical device technology. The labial gland biopsy needle module includes a biopsy needle tube, a force transmission component, and an coded identification element. One end of the force transmission component is connected to the biopsy needle tube, and the other end is an abutment face. The handle base module has a receiving cavity, and a second magnetic attraction part on the inner wall of the receiving cavity generates an axial magnetic attraction force with a first magnetic attraction part of the force transmission component, fixing the labial gland biopsy needle module. The force signal acquisition module includes a pre-tightening elastic element and a force-sensitive sensing unit. The pre-tightening elastic element and the axial magnetic attraction force together form an axial pre-tightening force, and the force-sensitive sensing unit acquires the axial force signal in real time. The dynamic calibration and processing module corrects the axial force signal based on the force signal reference zero point, retrieves a preset mechanical threshold according to the needle type parameters stored in the coded identification element, compares it with multi-domain mechanical characteristic values, generates a feedback command, and the interactive feedback module generates a feedback signal. This invention improves the reliability and safety of labial gland biopsy operations.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a dynamic calibration system and method for force feedback of a labial gland biopsy needle. Background Technology

[0002] Labial gland biopsy is an important method for diagnosing Sjögren's syndrome. During the procedure, the operator inserts a biopsy needle into the lower lip, passing through the mucosal epithelium and lamina propria to reach the glandular parenchyma in the submucosa for tissue sampling. Due to the differences in the mechanical properties of different tissue layers, the axial resistance varies as the needle penetrates each layer. Clinically, operators typically rely on tactile sensation to determine the needle depth and biopsy location. However, this tactile sensation is significantly influenced by individual operator differences, experience, and fatigue levels, making consistency in tactile judgment difficult to guarantee. Therefore, utilizing objective force feedback technology to assist in the biopsy procedure is essential to improving the success rate and safety of labial gland biopsies.

[0003] Several practical problems arise in implementing force feedback. First, biopsy needles are mostly detachable, disposable components, resulting in poor consistency in axial fit after each assembly. This leads to distortion or drift of the force signal during biopsy, failing to accurately reflect the true force on the needle tip. Second, existing systems often use static zeroing for calibration, which cannot eliminate the differences in initial force values ​​under different assembly states and the gravitational component error caused by changes in operating posture, resulting in inaccurate measurement baselines and affecting measurement accuracy. Furthermore, during biopsy, the mechanical response characteristics of biopsy needles of different specifications and geometries vary significantly. If the system only sets a fixed judgment threshold for a single needle type, the operator needs to recalibrate or manually switch parameter settings each time the needle type is changed, which is not only cumbersome but also prone to misjudgment due to parameter mismatch. Regarding tissue layer identification, existing systems rely solely on single temporal mechanical features. When faced with tissue interfaces with similar mechanical properties, they often fail to provide sufficient differentiation, leading to frequent missed or false alarms. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention proposes a dynamic calibration system and method for lip gland biopsy needle force feedback.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] A dynamic calibration system for force feedback of a labial gland biopsy needle, comprising:

[0007] The labial gland biopsy needle module is a passive mechanical structure, including a biopsy needle tube, a force transmission component, and a coding identification element. The force transmission component is provided with a first magnetic attraction part and extends along the axial direction of the labial gland biopsy needle module. One end is coaxially connected to the biopsy needle tube, and the other end forms an abutment end face. The coding identification element is disposed on the force transmission component and is used to store needle type parameters.

[0008] The handle base module has a receiving cavity for accommodating the labial gland biopsy needle module; the inner wall of the receiving cavity is provided with a second magnetic attraction part; the second magnetic attraction part and the first magnetic attraction part attract each other to generate an axial magnetic attraction force, so that the labial gland biopsy needle module is detachably fixed to the handle base module;

[0009] A force signal acquisition module is located at the bottom of the receiving cavity and includes a pre-tightening elastic element and a force-sensitive sensing unit. The pre-tightening elastic element is used to apply an axial elastic force to the force transmission component. The resultant force of the axial elastic force and the axial magnetic attraction force constitutes the axial pre-tightening force, so that the abutting end face continuously abuts against the force-sensitive surface of the force-sensitive sensing unit, so as to acquire the axial force signal in real time through the force-sensitive sensing unit.

[0010] The dynamic calibration and processing module is used to set the static force component as the zero point of the force signal reference during the static stage, and to dynamically correct the real-time axial force signal according to the zero point of the force signal reference. The multi-domain mechanical characteristic value of the dynamically corrected axial force signal is compared with the preset mechanical threshold value based on the needle parameter to generate feedback instructions.

[0011] The interactive feedback module is used to generate feedback signals based on feedback instructions.

[0012] As a preferred embodiment of the present invention, the handle base module further includes a sealing structure; the inner wall of the opening end of the receiving cavity is provided with an annular sealing shoulder, which is used to provide axial limitation for the sealing structure in the direction of the opening end;

[0013] The sealing structure is an elastic sealing ring, which is sleeved on the outside of the force transmission component. The side end of the elastic sealing ring facing the inside of the cavity has a pre-set axial gap of a predetermined size between it and the annular sealing shoulder. When the labial gland biopsy needle module is inserted into the cavity, it is squeezed and radially expanded by the force transmission component, so that the outer wall of the elastic sealing ring is interference-fitted with the inner wall of the cavity, and the inner wall of the elastic sealing ring is interference-fitted with the outer wall of the force transmission component, so as to prevent external liquid from seeping into the force-sensitive surface of the force-sensitive sensing unit.

[0014] As a preferred embodiment of the present invention, the force transmission component is further provided with an annular flange;

[0015] The pre-tightening elastic element includes a compression spring and a spring seat; the spring seat is fixed to the inner wall of the receiving cavity near the opening end; the compression spring is sleeved on the outside of the force transmission component and abuts against the spring seat and the annular flange. When the labial gland biopsy needle module is assembled in the receiving cavity, the compression spring is in a compressed state and applies an axial elastic force pointing towards the opening end of the receiving cavity to the annular flange.

[0016] At least one of the first magnetic attraction part and the second magnetic attraction part is a permanent magnet;

[0017] The axial magnetic attraction force points towards the bottom of the cavity, and the amplitude of the axial magnetic attraction force is greater than the amplitude of the axial elastic force.

[0018] As a preferred embodiment of the present invention, the force-sensitive sensing unit is a piezoresistive MEMS force sensor, which is fixed at the center of the bottom end face of the receiving cavity, with the force-sensitive surface facing the opening direction of the receiving cavity and coaxially aligned with the abutting end face of the force transmission component.

[0019] In a preferred embodiment of the present invention, the dynamic calibration and processing module is disposed inside the handle base module housing outside the receiving cavity, comprising:

[0020] The reading unit is used to read the pin type parameters stored in the coded recognition element;

[0021] The storage unit is used to store the mapping relationship table between needle type parameters and preset mechanical thresholds;

[0022] A signal preprocessing unit is used to acquire axial force signals in real time and preprocess the axial force signals; the preprocessing includes at least signal amplification, filtering, and analog-to-digital conversion;

[0023] The dynamic reference construction unit is used to collect pre-processed axial force signals within a preset time window as the target force signal set during the static stage after the labial gland biopsy needle module is assembled to the handle base module and before the biopsy operation is started. When the fluctuation index of the target force signal set is less than the preset stability threshold, the arithmetic mean of all axial force signals in the target force signal set is calculated as the static force component, and the static force component is set as the force signal reference zero point.

[0024] The dynamic correction unit is used to subtract the force signal reference zero point from the preprocessed real-time axial force signal during the biopsy operation to obtain the axial force correction signal.

[0025] The feature extraction unit is used to calculate the first derivative of the axial force correction signal with respect to time based on the axial force correction signal, as a time-domain mechanical feature value, and to perform a fast Fourier transform on the axial force correction signal to calculate the integral value of the power spectral density within a preset frequency band, as a frequency-domain mechanical feature value.

[0026] The threshold retrieval and feedback generation unit is used to automatically retrieve the corresponding preset mechanical threshold from the storage unit based on the needle type parameter. When the time domain mechanical characteristic value exceeds the first preset mechanical threshold, a first feedback instruction is generated; when the frequency domain mechanical characteristic value exceeds the second preset mechanical threshold, a second feedback instruction is generated.

[0027] As a preferred embodiment of the present invention, the dynamic calibration and processing module further includes a threshold adjustment unit; the threshold adjustment unit is configured as follows:

[0028] When the first feedback command is generated for the first time, the initial calibration value of the first preset mechanical threshold of the corresponding needle type is adjusted to a preset ratio of the initial calibration value, and the timing of the preset fallback time window is started.

[0029] If the temporal mechanical characteristic value is not detected to exceed the adjusted first preset mechanical threshold again at the end of the preset fallback time window, the first preset mechanical threshold will be restored to the initial calibration value.

[0030] If the temporal mechanical characteristic value exceeds the adjusted first preset mechanical threshold again within the preset fallback time window, the event is recorded without generating a new feedback command, and the timing of the preset fallback time window is restarted.

[0031] In a preferred embodiment of the present invention, the interactive feedback module is disposed inside the handle base module housing outside the receiving cavity;

[0032] The intensity of the feedback signal is positively correlated with the amplitude of the axial force correction signal, and the vibration frequency is generated based on the instantaneous rate of change in the time-domain mechanical characteristic value.

[0033] As a preferred embodiment of the present invention, it further includes:

[0034] The magnetic sensing module includes a magnetic field sensor, which is fixedly installed on the inner wall of the receiving cavity near the second magnetic suction part, with the sensitive surface facing the magnetic pole surface of the second magnetic suction part, and is used to detect the magnetic induction intensity of the second magnetic suction part.

[0035] The power module, located inside the handle base module housing on the outside of the receiving cavity, is used to provide operating voltage for the force signal acquisition module, dynamic calibration and processing module, interactive feedback module, and magnetic sensing detection module.

[0036] As a preferred embodiment of the present invention, the dynamic calibration and processing module further includes:

[0037] The pull-out detection unit is used to determine that the labial gland biopsy needle module is in the pull-out state when the detected magnetic induction intensity is lower than the preset disconnection threshold, and to record the axial force correction signal data segment corresponding to this biopsy process.

[0038] A dynamic calibration method for force feedback of a labial gland biopsy needle, comprising:

[0039] Real-time acquisition of axial force signals;

[0040] During the static settling phase, the static force components are calculated and set as the reference zero point for the force signal.

[0041] Dynamic correction of the axial force signal is performed based on the zero point of the force signal reference.

[0042] Calculate the multi-domain mechanical characteristic values ​​of the dynamically corrected axial force signal, and retrieve the preset mechanical threshold based on the needle type parameters;

[0043] The multi-domain mechanical feature values ​​are compared with preset mechanical thresholds, and feedback instructions are generated based on the comparison results.

[0044] Feedback signals are generated based on feedback instructions.

[0045] The beneficial effects of this invention are as follows: By applying axial preload to the force transmission component through the preload elastic element, the contact end face of the force transmission component maintains continuous contact with the force-sensitive surface of the force-sensitive sensing unit. This eliminates the problem of intermittent force transmission caused by assembly gaps in detachable connection methods, and avoids distortion or interruption of the axial force signal during biopsy due to the momentary separation of the contact end face from the force-sensitive surface. This ensures that the axial force on the needle tip can be transmitted completely and continuously to the force-sensitive sensing unit, laying a solid hardware foundation for force measurement. Furthermore, based on the zero point of the force signal reference during the static stage, the real-time axial force signal is dynamically corrected, overcoming the limitations of traditional static zeroing methods that cannot adapt to different assembly states and operational posture changes, thus improving the accuracy and consistency of the measurement reference. Furthermore, by storing needle type parameters through an coded identification element, the dynamic calibration and processing module reads these parameters and automatically retrieves the matching preset mechanical thresholds. This allows for immediate use after changing needle types, eliminating the need for manual recalibration or parameter switching. While ensuring that different sizes of labial gland biopsy needles can obtain matching preset mechanical thresholds, this simplifies the operation process and improves the system's versatility and ease of use. Finally, the dynamic calibration and processing module extracts multi-domain mechanical feature values ​​from the dynamically corrected axial force signal and compares them with the adapted preset mechanical thresholds in multiple dimensions. Based on the comparison results, it generates feedback commands, driving the interactive feedback module to output corresponding feedback signals. This feedback mechanism, which combines multi-domain mechanical feature analysis, comprehensively reflects the mechanical state of the needle tip-tissue interaction from multiple dimensions. Compared to a single mechanical threshold judgment method, this improves the accuracy and anti-interference capability of tissue penetration event detection, providing operators with more reliable biopsy guidance and enhancing the consistency, reliability, and safety of labial gland biopsy procedures. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 A modular structure diagram of a dynamic calibration system for lip gland biopsy needle force feedback provided by the present invention; Figure 2 This is a schematic diagram of the dynamic calibration and processing module in an embodiment of the present invention; Figure 3 for Figure 2 Flowchart of dynamic threshold adjustment for the feedback instruction generation unit; Figure 4 The flowchart illustrates a dynamic calibration method for lip gland biopsy needle force feedback provided by this invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0048] like Figure 1 As shown, this is an embodiment of the present invention, which provides a dynamic calibration system for labial gland biopsy needle force feedback. The system includes a labial gland biopsy needle module, a handle base module, a force signal acquisition module, a dynamic calibration and processing module, an interactive feedback module, a magnetic sensing detection module, and a power supply module.

[0049] The labial gland biopsy needle module is a passive mechanical structure, including a biopsy needle tube, a force transmission component, and a coding identification element.

[0050] The force transmission component has a first magnetic attraction part that extends axially along the labial gland biopsy needle module. One end is coaxially connected to the biopsy needle tube, and the other end forms an abutment face. This force transmission component is made of medical-grade rigid material and has an overall columnar or rod-shaped structure with an axial stiffness of not less than 100 N / mm. This ensures that within the typical puncture force range of a labial gland biopsy, the axial elastic deformation of the force transmission component does not exceed 40 μm, which is far less than the equivalent displacement corresponding to the force resolution of the force-sensitive sensing unit, thus guaranteeing the accuracy of axial force transmission and the stability of the magnetic connection. The medical-grade rigid material includes medical-grade stainless steel, titanium alloy, or zirconia ceramic. The force transmission component also has an annular flange located on the side of the force transmission component near the opening of the handle base module's receiving cavity.

[0051] The coding and identification element is disposed on the force transmission component and is used to store needle type parameters. The coding and identification element is a QR code, barcode, or conductive contact type coding structure. The conductive contact type coding structure consists of several passive contacts, and the needle type parameters are characterized by the combination of on and off states of the contacts. The needle type parameters include at least the needle diameter specification, needle tip configuration, and nominal length.

[0052] The handle base module has a receiving cavity for accommodating the labial gland biopsy needle module; the inner wall of the receiving cavity is provided with a second magnetic attraction part, which attracts the first magnetic attraction part to generate an axial magnetic attraction force so that the labial gland biopsy needle module can be detachably fixed to the handle base module.

[0053] At least one of the first and second magnetic attraction parts is a permanent magnet. In this embodiment, the first magnetic attraction part is a ferromagnetic metal ring, which is fixedly sleeved on the outer wall of the force transmission member near the abutment end face; the second magnetic attraction part is a permanent magnet ring, which is fixedly disposed at the corresponding position on the inner wall of the receiving cavity; the axial magnetic attraction force of the permanent magnet ring is not less than 5N, which is much greater than the typical axial reaction force during labial gland biopsy, to ensure that the labial gland biopsy needle module will not accidentally detach from the handle base module during the biopsy.

[0054] The handle base module also includes a sealing structure; the inner wall of the opening end of the receiving cavity is provided with an annular sealing shoulder, which is used to provide axial restraint for the sealing structure in the direction of the opening end; the sealing structure is an elastic sealing ring, which is sleeved on the outside of the force transmission component, and an axial gap of a preset size is reserved between the end face of the elastic sealing ring facing the inside of the receiving cavity and the annular sealing shoulder. The preset size is preferably 0.8mm to 1.2mm.

[0055] The working process of the sealing structure is as follows:

[0056] When the labial gland biopsy needle module is not inserted, the elastic sealing ring is freely fitted onto the force transmission component, with an axial gap reserved between it and the annular sealing shoulder. At this time, the elastic sealing ring is in a free state, and the inner diameter is in clearance fit or slight interference fit with the outer wall of the force transmission component to facilitate initial insertion. When the labial gland biopsy needle module begins to be inserted into the receiving cavity, the elastic sealing ring moves towards the bottom of the receiving cavity along with the force transmission component. Due to the existence of the axial gap, it is not blocked by the annular sealing shoulder, resulting in low insertion resistance. When the labial gland biopsy needle module is inserted to the preset depth corresponding to the imminent engagement of the first and second magnetic suction parts, the bottom-facing end face of the elastic sealing ring abuts against the annular sealing shoulder, restricting the axial movement of the elastic sealing ring. Subsequently, the force transmission component continues to move towards the bottom of the receiving cavity. The elastic sealing ring, axially limited by the annular sealing shoulder, experiences axial relative displacement relative to the force transmission component. Under the continuous compression of the outer wall of the force transmission component, it undergoes radial expansion deformation, resulting in an interference fit between the outer wall of the elastic sealing ring and the inner wall of the receiving cavity, and an interference fit between the inner wall and the outer wall of the force transmission component, forming a bidirectional radial seal to prevent external liquid from seeping into the force-sensitive surface of the force-sensitive sensing unit. The preset depth is the axial insertion distance from the opening end of the receiving cavity to the end face of the annular flange, calculated using the following formula:

[0057]

[0058] in, Preset depth; The magnetic attraction depth is the depth at which the first magnetic attraction part and the second magnetic attraction part are fully engaged. The value of the pre-stroke amount is preferably in the range of 0.8 mm to 1.5 mm.

[0059] The force signal acquisition module is located at the bottom of the receiving cavity and includes a pre-tightening elastic element and a force-sensitive sensing unit.

[0060] The preload elastic element applies an axial elastic force to the force transmission component. The resultant force of this axial elastic force and the axial magnetic attraction constitutes the axial preload, ensuring that the contact end face continuously abuts against the force-sensitive surface of the force-sensitive sensing unit, allowing the force-sensitive sensing unit to acquire axial force signals in real time. The preload elastic element includes a compression spring and a spring seat. The spring seat is fixed to the inner wall of the receiving cavity near the opening end. The compression spring is sleeved on the outside of the force transmission component and abuts against the spring seat and the annular flange. When the labial gland biopsy needle module is assembled in the receiving cavity, the compression spring is in a compressed state and applies an axial elastic force pointing towards the opening end of the receiving cavity to the annular flange. The axial magnetic attraction points towards the bottom of the receiving cavity, and the amplitude of the axial magnetic attraction is greater than the amplitude of the axial elastic force. This axial preload is determined by the stiffness coefficient and initial compression of the compression spring. To ensure a stable force transmission link can be established for all specifications of labial gland biopsy needle modules, the design value of this axial preload is set within the mechanical design range of 0.2N to 2N.

[0061] The force-sensitive sensing unit is a piezoresistive MEMS force sensor, fixed at the center of the bottom end face of the receiving cavity, with the force-sensitive surface facing the opening of the receiving cavity and coaxially aligned with the contact end face of the force transmission component. In this embodiment, the rated range of the piezoresistive MEMS force sensor is 0N to 10N, the sensitivity is not less than 2mV / V / N, the nonlinearity is not greater than ±1%FS, the zero-point drift is not greater than ±0.5%FS / °C, and the operating temperature range is 0°C to 50°C.

[0062] The dynamic calibration and processing module is located inside the handle base module housing outside the receiving cavity. It is used to set the static force component as the zero point of the force signal reference during the static stage, and to dynamically correct the real-time axial force signal according to the zero point of the force signal reference. The multi-domain mechanical characteristic value of the dynamically corrected axial force signal is compared with the preset mechanical threshold value based on the needle type parameter to generate feedback command.

[0063] like Figure 2 As shown, the dynamic calibration and processing module includes a reading unit, a storage unit, a signal preprocessing unit, a dynamic benchmark construction unit, a dynamic correction unit, a feature extraction unit, and a threshold retrieval and feedback generation unit.

[0064] The reading unit is used to read the pin type parameters stored in the coded identification element.

[0065] The storage unit stores a mapping table between needle type parameters and preset mechanical thresholds. In this mapping table, each needle type parameter is associated with a first preset mechanical threshold, a second preset mechanical threshold, and a target preload value. All three types of mechanical parameters are calibrated through ex vivo tissue biopsy experiments. Specifically, using ex vivo tissue samples with mechanical properties similar to the target biopsy tissue, multiple biopsies are performed on beveled needles of various sizes at a constant insertion speed of 1 mm / s, and axial force versus time curves are collected. For each needle diameter, the mean of the peak value of the first-order time derivative of the axial force signal from each biopsy, plus three times the standard deviation, is used as the first preset mechanical threshold; the mean of the power spectral density integral value within a preset frequency band from each biopsy, plus three times the standard deviation, is used as the second preset mechanical threshold; the target preload value is set to 1.2 to 1.5 times the peak value of the maximum puncture reaction force measured in the ex vivo tissue biopsy experiment, and its value is limited to the mechanical design range of 0.2N to 2N.

[0066] For example, when the labial gland biopsy needle has a diameter of 18G and a beveled tip, the corresponding first preset mechanical threshold is 20N / s, the second preset mechanical threshold is 0.08N², and the target preload is 0.8N; when the labial gland biopsy needle has a diameter of 20G and a beveled tip, the corresponding first preset mechanical threshold is 15N / s, the second preset mechanical threshold is 0.05N², and the target preload is 0.5N; when the labial gland biopsy needle has a diameter of 22G and a beveled tip, the corresponding first preset mechanical threshold is 10N / s, the second preset mechanical threshold is 0.03N², and the target preload is 0.3N.

[0067] The spring stiffness coefficient and initial compression corresponding to the target preload value have been calibrated at the factory. When the system identifies a specific needle type, the dynamic calibration and processing module reads the corresponding target preload value and compares it with the signal component representing the axial preload in the axial force signal output by the force-sensitive sensing unit under the current actual assembly state. If the deviation exceeds the preset tolerance range, an assembly abnormality alarm is issued through the interactive feedback module. The preset tolerance range is set to ±15%.

[0068] The signal preprocessing unit is used to acquire and preprocess the axial force signal in real time. The axial force signal is acquired in real time at a sampling rate of 1kHz. The processing includes at least signal amplification, filtering, and analog-to-digital conversion. Since the force-sensitive sensing unit used in this system is a piezoresistive MEMS force sensor, it outputs a differential voltage signal proportional to the magnitude of the applied force under the excitation voltage. This differential voltage signal has a low amplitude and is mixed with high-frequency interference. First, the differential voltage signal is amplified by an instrumentation amplifier to meet the input range requirements of the analog-to-digital converter (ADC). Then, a second-order active low-pass filter is used to filter out high-frequency interference components to avoid signal aliasing affecting subsequent sampling accuracy. Subsequently, the ADC converts the signal into a digital signal. Finally, digital filtering and denoising are performed in the digital domain to obtain the preprocessed axial force signal. As an optional configuration, the gain of the instrumentation amplifier is set to 100 times; the cutoff frequency of the second-order active low-pass filter is set to 150Hz, and the stopband attenuation is set to -40dB / decade; the ADC is a 16-bit ADC with a reference voltage of 3.3V and a sampling rate of 1kHz. The gain of the instrumentation amplifier, the cutoff frequency of the low-pass filter, and the sampling rate of the analog-to-digital converter can all be adaptively adjusted according to the type of force sensor selected.

[0069] The dynamic reference construction unit is used to collect pre-processed axial force signals within a preset time window as the target force signal set during the static stage after the labial gland biopsy needle module is assembled to the handle base module and before the biopsy operation is started. When the fluctuation index of the target force signal set is less than the preset stability threshold, the arithmetic mean of all axial force signals in the target force signal set is calculated as the static force component, and the static force component is set as the zero point of the force signal reference.

[0070] After the system is powered on, it enters a static phase lasting 2 seconds. The operator only needs to keep the handle base module stationary, ensuring the labial gland biopsy needle module does not contact any external objects. There is no need to restrict the spatial orientation of the biopsy needle. The pre-processed axial force signal from the last second of the static phase is selected as the target force signal set. The fluctuation index is the standard deviation of the axial force signal in the target force signal set. The preset stability threshold is set based on the static noise level of the force-sensitive sensing unit, taking 2 to 3 times the standard deviation of the static noise, or 0.02N to 0.05N. This force signal reference zero point includes both the signal component generated by the axial preload and the axial component of the labial gland biopsy needle module's own weight. Considering that the labial gland biopsy insertion depth is generally 3mm to 5mm, and the total operation time is approximately 1 to 3 seconds, a 2-second calibration duration ensures signal stability without excessively extending the preparation time.

[0071] The dynamic correction unit is used to subtract the force signal reference zero point from the preprocessed real-time axial force signal during the biopsy procedure to obtain the axial force correction signal. This axial force correction signal may have a negative value, indicating that the tip of the labial gland biopsy needle is experiencing resistance in the direction of the opening or that the operator's hand is withdrawn.

[0072] The feature extraction unit is used to calculate the first derivative of the axial force correction signal with respect to time based on the axial force correction signal, as a time-domain mechanical feature value, and to perform a fast Fourier transform on the axial force correction signal to calculate the integral value of the power spectral density within a preset frequency band, as a frequency-domain mechanical feature value.

[0073] The formula for calculating the eigenvalues ​​of time-domain mechanics is:

[0074]

[0075] in, The sampling point number corresponds to the time. ; For the first Temporal mechanical eigenvalues ​​at each sampling point; The sampling interval is... , For the sampling rate, in this embodiment... Take 1kHz; For the first Axial force correction signal at each sampling point; For the first Axial force correction signal at one sampling point. Calculation. First, to A 5-point moving average smoothing process is performed to suppress the interference of high-frequency noise on the difference.

[0076] The steps for calculating frequency domain eigenvalues ​​include:

[0077] The baseline-corrected axial force signal is captured in real time using a sliding window with a length of 256 points and an overlap rate of 50%. A Hanning window is applied to each window, followed by a Fast Fourier Transform (FFT). The power spectral density is obtained by squared the modulus of the FFT result and dividing by the frequency resolution. The frequency resolution is... , This is the window length.

[0078] The integral value of the power spectral density within the preset frequency band, i.e., the frequency domain mechanical eigenvalue, is calculated using the following formula:

[0079]

[0080] in, These are frequency domain mechanical eigenvalues; It is the power spectral density function; This is the lower limit frequency of the preset frequency band; This is the upper limit frequency of the preset frequency band. The preset frequency band is set to... to .

[0081] The threshold retrieval and feedback generation unit is used to automatically retrieve the corresponding preset mechanical threshold from the storage unit based on the needle type parameter. When the time domain mechanical characteristic value exceeds the first preset mechanical threshold, a first feedback instruction is generated; when the frequency domain mechanical characteristic value exceeds the second preset mechanical threshold, a second feedback instruction is generated.

[0082] The first feedback command indicates a step change in the axial force signal after baseline correction, corresponding to a sudden drop in mechanical impedance during the advancement of the labial gland biopsy needle tip; for example, the interface breakthrough experienced when the needle tip penetrates from the lamina propria, which has higher resistance, into the glandular parenchyma, which has lower resistance. Figure 3 As shown, to further reduce repeated false triggers within the same tissue layer, the threshold retrieval and feedback generation unit performs adaptive threshold adjustment after generating the first feedback command. Specifically, when the first feedback command is triggered for the first time, the threshold retrieval and feedback generation unit temporarily adjusts the initial calibration value of the first preset mechanical threshold corresponding to the needle type to 120% to 150% of the initial calibration value and starts the timing of the preset fallback time window; if no further triggering occurs by the end of the preset fallback time window, the first preset mechanical threshold is restored to the initial calibration value corresponding to the needle type, preparing to detect the penetration event of the next tissue layer; if the time domain feature value is detected to exceed the adjusted first preset mechanical threshold again within the preset fallback time window, only the event is recorded without generating a new first feedback command, and the timing of the preset fallback time window is restarted. The default value of the preset fallback time window is 3 seconds, which can be configured within the range of 2 to 5 seconds.

[0083] When the needle tip is located in the mucosal epithelial layer, the frequency domain mechanical characteristic value is low within the 20Hz to 100Hz frequency band. Upon penetrating the lamina propria, the frequency domain mechanical characteristic value increases significantly due to the coupling of micro-vibrational energy generated by the fibrous structure. After entering the glandular parenchyma, the damping characteristics of the acinar structure cause the frequency domain mechanical characteristic value to stabilize. Therefore, changes in the frequency domain mechanical characteristic value can provide the operator with auxiliary reference information on the transition between tissue layers. The system itself does not make a definitive diagnostic conclusion on the tissue layer; the final judgment is made by the operator based on clinical experience.

[0084] An interactive feedback module, located inside the handle base module housing on the outside of the receiving cavity, is used to generate feedback signals based on feedback commands. The interactive feedback module includes at least one of a vibration motor, a buzzer, an LED indicator, and a micro display screen.

[0085] Within the same processing cycle, if it is determined that a first feedback instruction and a second feedback instruction need to be generated simultaneously, the interactive feedback module will execute them according to the priority of the first feedback instruction first, followed by the second feedback instruction: first, the feedback signal corresponding to the first feedback instruction will be output, and after an interval of no less than 200 milliseconds, the feedback signal corresponding to the second feedback instruction will be output. If the triggering condition of another feedback instruction is met while the feedback signal corresponding to the first or second feedback instruction is being executed, the interactive feedback module will wait for the currently output feedback signal to complete, and after an interval of no less than 200 milliseconds, the feedback signal corresponding to the newly triggered feedback instruction will be output.

[0086] The interactive feedback module parses feedback instructions through a microcontroller to obtain the intensity and vibration frequency of the feedback signal, and controls the vibration motor to operate via a pulse width modulation signal. In this embodiment, the vibration motor is a linear resonant motor with a resonant frequency of 200 Hz and a resonant bandwidth of ±15 Hz.

[0087] The intensity of the feedback signal is positively correlated with the amplitude of the axial force correction signal, and the vibration frequency is generated based on the instantaneous rate of change in the time-domain mechanical eigenvalues. The formula for calculating the intensity of the feedback signal is:

[0088]

[0089] in, The strength of the feedback signal; The amplitude of the axial force correction signal; For intensity mapping coefficients, in this embodiment Take 0.4 / N; The base strength offset is 0.1 in this embodiment.

[0090] The formula for calculating the vibration frequency is:

[0091]

[0092] in, This is a time-domain mechanical characteristic value, with units of N / s; The frequency mapping coefficient is taken as 0.5 Hz / (N / s) in this embodiment; The base frequency is 195Hz in this embodiment; The frequency is the vibration frequency.

[0093] when When the value exceeds 1, take 1; when When the value is below 0, take 0. When the resonant bandwidth of the linear resonant motor is exceeded, Limiting to the boundary value of the resonant bandwidth.

[0094] The magnetic sensing module includes a magnetic field sensor, which is fixedly installed on the inner wall of the receiving cavity near the second magnetic attraction part, with its sensitive surface facing the magnetic pole surface of the second magnetic attraction part, for detecting the magnetic induction intensity of the second magnetic attraction part. This magnetic field sensor is a Hall effect sensor.

[0095] The dynamic calibration and processing module also includes a pull-out detection unit, which determines that the labial gland biopsy needle module is in the pull-out state when the detected magnetic induction intensity is lower than the preset disconnection threshold, and records the axial force correction signal data segment corresponding to this biopsy process for retrieval and analysis. When the labial gland biopsy needle module is pulled out, the first magnetic suction part moves away with the labial gland biopsy needle module, the distance between it and the second magnetic suction part increases, and the magnetic induction intensity decreases accordingly. The start time of the biopsy operation is determined by the first time the axial force correction signal exceeds the preset start threshold, and the end time of the biopsy operation is determined by the pull-out state of the labial gland biopsy needle module. In this embodiment, the preset start threshold is 0.2N. This preset start threshold is higher than the noise level after dynamic calibration and lower than the minimum puncture force peak value, which can avoid noise false triggering and ensure detection sensitivity; the preset disconnection threshold is set to 30% to 50% of the initial measurement value of magnetic induction intensity in the assembled state, and in this embodiment, it is 40%. The initial measurement value of magnetic induction intensity in the assembled state refers to the magnetic induction intensity measured by the Hall effect sensor when the labial gland biopsy needle module and the handle base module are fully assembled and the pre-tightened elastic element is in the working compression state. This measurement is completed during the system power-on and static stage, and the result is stored in the memory.

[0096] The power module, using a rechargeable lithium battery or button cell battery, is located inside the handle base module housing on the outside of the receiving cavity. It provides operating voltage to the force signal acquisition module, dynamic calibration and processing module, interactive feedback module, and magnetic sensing detection module. In this embodiment, the power module uses a 3.7V rechargeable lithium battery and is equipped with a charge / discharge management circuit and a voltage regulator circuit. The voltage regulator circuit outputs a 3.3V voltage, and the handle base module housing has a corresponding charging interface, such as a USB Type-C interface, for charging the battery from an external power source.

[0097] like Figure 4 As shown, another embodiment of the present invention provides a dynamic calibration method for labial gland biopsy needle force feedback, comprising:

[0098] S1, real-time acquisition of axial force signals.

[0099] S2, during the static stage, calculate the static force component and set the static force component as the zero point of the force signal reference.

[0100] S3 dynamically corrects the axial force signal based on the zero point of the force signal reference.

[0101] S4 calculates the multi-domain mechanical characteristic value of the dynamically corrected axial force signal and retrieves the preset mechanical threshold based on the needle type parameter.

[0102] S5 compares the multi-domain mechanical feature values ​​with the preset mechanical threshold, and generates feedback instructions based on the comparison results.

[0103] S6 generates a feedback signal based on the feedback instruction.

[0104] The specific implementation of each step from S1 to S6 is the same as that in the above system embodiment, and will not be repeated here.

[0105] In summary, this invention generates axial preload through the synergistic action of a compression spring and an annular flange, coupled with magnetic retention by a permanent magnet, ensuring reliable coaxial contact between the labial gland biopsy needle and the force-sensitive sensing unit. This eliminates force transmission distortion caused by gaps in traditional mechanical snap-fit ​​mechanisms. Combined with a progressive radial sealing structure, it maintains low resistance during initial insertion and automatically forms a bidirectional radial seal upon successful insertion. This overcomes friction and gravity interference while meeting the sealing requirements of a moist oral environment, laying a solid hardware foundation for force feedback. Furthermore, by setting the static force component during the resting phase as the zero point of the force signal reference, the axial preload and the needle's own weight are separated in real time. This overcomes the limitations of traditional static zeroing methods that cannot handle assembly differences and posture changes, improving the measurement accuracy of the axial force signal under different operating postures. Furthermore, by automatically retrieving preset mechanical thresholds matching the needle type parameters through the coded recognition element, the system solves the adaptation problem of large differences in the mechanical properties of different specifications of labial gland biopsy needles. The system simultaneously calculates the time-domain and frequency-domain mechanical characteristic values ​​of the axial force correction signal. The time-domain mechanical characteristic value reflects the instantaneous change of the axial force signal and is used to detect the impedance drop when the needle tip penetrates the tissue interface. The frequency-domain characteristic value reflects the energy distribution within a preset frequency band, providing supplementary information for tissue type determination. The two types of features work together and temporarily adjust the preset mechanical threshold after the first trigger to suppress repeated false triggers within the same tissue layer, improving the accuracy and anti-interference capability of force feedback. Furthermore, the system detects the magnetic induction intensity of the second magnetic suction part through the magnetic induction detection module, automatically determines the withdrawal time of the labial gland biopsy needle module, and records the axial force correction signal data segment corresponding to this biopsy process, providing traceable mechanical reference data for clinical operation. Finally, through the synergistic effects of the above structural design, dynamic calibration, needle type adaptation, multi-domain feature joint analysis, and process recording, a complete technical solution is formed that covers the entire chain from acquisition, processing, and identification of coverage force signals to process recording, thereby improving the reliability and safety of lip gland biopsy operations.

[0106] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dynamic calibration system for force feedback of a labial gland biopsy needle, characterized in that, include: The labial gland biopsy needle module is a passive mechanical structure, including a biopsy needle tube, a force transmission component, and a coding identification element. The force transmission component is provided with a first magnetic attraction part and extends along the axial direction of the labial gland biopsy needle module. One end is coaxially connected to the biopsy needle tube, and the other end forms an abutment end face. The coding identification element is disposed on the force transmission component and is used to store needle type parameters. The handle base module has a receiving cavity for accommodating the labial gland biopsy needle module; the inner wall of the receiving cavity is provided with a second magnetic attraction part; the second magnetic attraction part and the first magnetic attraction part attract each other to generate an axial magnetic attraction force, so that the labial gland biopsy needle module is detachably fixed to the handle base module; A force signal acquisition module is located at the bottom of the receiving cavity and includes a pre-tightening elastic element and a force-sensitive sensing unit. The pre-tightening elastic element is used to apply an axial elastic force to the force transmission component. The resultant force of the axial elastic force and the axial magnetic attraction force constitutes the axial pre-tightening force, so that the abutting end face continuously abuts against the force-sensitive surface of the force-sensitive sensing unit, so as to acquire the axial force signal in real time through the force-sensitive sensing unit. The dynamic calibration and processing module is used to set the static force component as the zero point of the force signal reference during the static stage, and to dynamically correct the real-time axial force signal according to the zero point of the force signal reference. The multi-domain mechanical characteristic value of the dynamically corrected axial force signal is compared with the preset mechanical threshold value based on the needle parameter to generate feedback instructions. The interactive feedback module is used to generate feedback signals based on feedback instructions.

2. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 1, characterized in that, The handle base module also includes a sealing structure; the inner wall of the opening end of the receiving cavity is provided with an annular sealing shoulder, which is used to provide axial restraint for the sealing structure in the direction of the opening end; The sealing structure is an elastic sealing ring, which is sleeved on the outside of the force transmission component. The side end of the elastic sealing ring facing the inside of the cavity has a pre-set axial gap of a predetermined size between it and the annular sealing shoulder. When the labial gland biopsy needle module is inserted into the cavity, it is squeezed and radially expanded by the force transmission component, so that the outer wall of the elastic sealing ring is interference-fitted with the inner wall of the cavity, and the inner wall of the elastic sealing ring is interference-fitted with the outer wall of the force transmission component, so as to prevent external liquid from seeping into the force-sensitive surface of the force-sensitive sensing unit.

3. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 1, characterized in that, The force transmission component is also provided with an annular flange; The pre-tightening elastic element includes a compression spring and a spring seat; the spring seat is fixed to the inner wall of the receiving cavity near the opening end; the compression spring is sleeved on the outside of the force transmission component and abuts against the spring seat and the annular flange. When the labial gland biopsy needle module is assembled in the receiving cavity, the compression spring is in a compressed state and applies an axial elastic force pointing towards the opening end of the receiving cavity to the annular flange. At least one of the first magnetic attraction part and the second magnetic attraction part is a permanent magnet; The axial magnetic attraction force points towards the bottom of the cavity, and the amplitude of the axial magnetic attraction force is greater than the amplitude of the axial elastic force.

4. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 1, characterized in that, The force-sensitive sensing unit is a piezoresistive MEMS force sensor, which is fixed at the center of the bottom end face of the receiving cavity, with the force-sensitive surface facing the opening of the receiving cavity and coaxially aligned with the contact end face of the force transmission component.

5. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 1, characterized in that, The dynamic calibration and processing module is located inside the handle base module housing outside the receiving cavity, and includes: The reading unit is used to read the pin type parameters stored in the coded recognition element; The storage unit is used to store the mapping relationship table between needle type parameters and preset mechanical thresholds; The signal preprocessing unit is used to acquire axial force signals in real time and preprocess the axial force signals; the preprocessing includes at least signal amplification, filtering and analog-to-digital conversion; the dynamic reference construction unit is used to collect the preprocessed axial force signals within a preset time window as the target force signal set during the static stage after the labial gland biopsy needle module is assembled to the handle base module and before the biopsy operation is started. When the fluctuation index of the target force signal set is less than the preset stability threshold, the arithmetic mean of all axial force signals in the target force signal set is calculated as the static force component, and the static force component is set as the force signal reference zero point. The dynamic correction unit is used to subtract the reference zero point of the force signal from the preprocessed real-time axial force signal during the biopsy operation to obtain the axial force correction signal; the feature extraction unit is used to calculate the first derivative of the axial force correction signal with respect to time based on the axial force correction signal as the time-domain mechanical feature value, and to perform a fast Fourier transform on the axial force correction signal to calculate the integral value of the power spectral density within a preset frequency band as the frequency-domain mechanical feature value. The threshold retrieval and feedback generation unit is used to automatically retrieve the corresponding preset mechanical threshold from the storage unit based on the needle type parameter. When the time domain mechanical characteristic value exceeds the first preset mechanical threshold, a first feedback instruction is generated; when the frequency domain mechanical characteristic value exceeds the second preset mechanical threshold, a second feedback instruction is generated.

6. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 5, characterized in that, The dynamic calibration and processing module further includes a threshold adjustment unit; the threshold adjustment unit is configured to: When the first feedback command is generated for the first time, the initial calibration value of the first preset mechanical threshold of the corresponding needle type is adjusted to a preset ratio of the initial calibration value, and the timing of the preset fallback time window is started. If the temporal mechanical characteristic value is not detected to exceed the adjusted first preset mechanical threshold again at the end of the preset fallback time window, the first preset mechanical threshold is restored to the initial calibration value. If the temporal mechanical characteristic value exceeds the adjusted first preset mechanical threshold again within the preset fallback time window, the event is recorded without generating a new feedback command, and the timing of the preset fallback time window is restarted.

7. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 5, characterized in that, Also includes: The interactive feedback module is located inside the handle base module housing outside the receiving cavity; The intensity of the feedback signal is positively correlated with the amplitude of the axial force correction signal, and the vibration frequency is generated based on the instantaneous rate of change in the time-domain mechanical characteristic value.

8. The dynamic calibration system for labial gland biopsy needle force feedback according to claim 5, characterized in that, Also includes: The magnetic sensing module includes a magnetic field sensor, which is fixedly installed on the inner wall of the receiving cavity near the second magnetic suction part, with the sensitive surface facing the magnetic pole surface of the second magnetic suction part, and is used to detect the magnetic induction intensity of the second magnetic suction part. The power module, located inside the handle base module housing on the outside of the receiving cavity, is used to provide operating voltage for the force signal acquisition module, dynamic calibration and processing module, interactive feedback module, and magnetic sensing detection module.

9. A dynamic calibration system for labial gland biopsy needle force feedback according to claim 8, characterized in that, The dynamic calibration and processing module also includes: The pull-out detection unit is used to determine that the labial gland biopsy needle module is in the pull-out state when the detected magnetic induction intensity is lower than the preset disconnection threshold, and to record the axial force correction signal data segment corresponding to this biopsy process.

10. A dynamic calibration method for force feedback of a labial gland biopsy needle, applied to the dynamic calibration system for force feedback of a labial gland biopsy needle as described in any one of claims 1 to 9, characterized in that, include: Real-time acquisition of axial force signals; During the static settling phase, the static force components are calculated and set as the reference zero point for the force signal. Dynamic correction of axial force signal is performed based on the zero point of force signal reference. Calculate the multi-domain mechanical characteristic values ​​of the dynamically corrected axial force signal, and retrieve the preset mechanical threshold based on the needle type parameters; The multi-domain mechanical feature values ​​are compared with preset mechanical thresholds, and feedback instructions are generated based on the comparison results. Feedback signals are generated based on feedback instructions.

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