Method for controlling cutting force of electric linear cutting anastomat

Abstract

The invention discloses a cutting force control method of an electric linear cutting anastomat, which is characterized in that the cutting force is accurately calculated by adopting a nonlinear index correction model by collecting the current, the rotating speed and the tissue thickness of a motor in real time. The tissue type is judged according to the cutting force, the cutting speed is dynamically adjusted, and meanwhile safety protection and a cutting termination mechanism are set. According to the method, parameters are adaptively updated through a moving average method, and adaptability is improved. The method is simple in calculation and suitable for the electric anastomat, and operation safety and accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a method for controlling the cutting force of an electric linear cutting stapler. By monitoring motor parameters and tissue characteristics, the cutting force is accurately calculated and the cutting parameters are dynamically adjusted to improve the safety and accuracy of surgery, and it is particularly suitable for tissue cutting and stapling operations in minimally invasive surgery. Background Art

[0002] The electric linear cutting stapler is an indispensable tool in modern minimally invasive surgery, and is widely used in scenarios such as gastrointestinal surgery and lobectomy, for completing stapling to close the incision while cutting tissues. With the popularization of minimally invasive technology, the performance requirements for staplers are increasing day by day, especially in the precise control of cutting force. The reasonable control of cutting force not only affects the success rate of surgery, but also directly relates to the postoperative tissue healing effect and the patient's recovery. However, there are still many deficiencies in the cutting force control of the existing technology, which limits the intelligent and safe development of staplers.

[0003] Traditional handheld or electric staplers mainly rely on mechanical structures to achieve cutting and stapling functions. For example, early devices completed cutting through the mechanical linkage of a push rod and a blade, and the operator needed to adjust the cutting force based on experience. This method lacks real-time monitoring of the cutting force and is difficult to adapt to the characteristic differences of different tissue types (such as soft tissue, hard tissue or scar tissue), which may lead to incomplete cutting or excessive tissue damage. For example, the patent document CN102068290A describes a linear cutting stapler that achieves safety limitation through a mechanical floating block design, but does not involve dynamic monitoring or accurate calculation of the cutting force, and relies on the inherent characteristics of the mechanical design, making it difficult to handle complex situations during surgery.

[0004] With the development of electric technology, modern staplers have begun to introduce a motor drive mechanism, improving the operation convenience and consistency. Some devices have achieved a preliminary force feedback function by monitoring motor current or torque. For example, the Signia intelligent stapling system launched by Medtronic uses motor feedback to adjust the stapling speed and optimize the formation effect of the staple line. However, this feedback mechanism mainly focuses on the stapling process, and the control of cutting force has not been fully concerned. Existing literature shows that if the cutting force control only relies on a simple linear model (such as direct proportional calculation based on current), it often ignores the non-linear mechanical characteristics of tissues, such as the exponential effect of tissue thickness on resistance, or the complex relationship between motor speed and cutting efficiency. This simplification leads to a large deviation between the calculation result and the actual cutting force, and it is difficult to ensure the accuracy and safety of cutting, especially when dealing with tissues with uneven thickness or changing hardness.

[0005] In addition, the real-time monitoring of tissue thickness and hardness has not been fully integrated in the prior art. Patent US7159749B2 proposes a stapler capable of cutting staple legs, which senses thickness through mechanical clamping. However, this method belongs to static adjustment and cannot dynamically respond to tissue changes during the cutting process. Similarly, Patent US20120024936A1 describes a stapler design for selective cutting, which realizes function switching through the separation mechanism of the push rod and the blade, and still does not involve a real-time mechanical model or dynamic feedback of tissue characteristics. These limitations of the prior art make staplers prone to problems such as cutting failure, tissue tearing, or postoperative leakage when facing complex surgical scenarios (such as uneven tissue thickness or abnormal hardness).

[0006] In recent years, some studies have attempted to introduce sensor technology into staplers to improve the level of intelligence. For example, Patent EP2462878A1 proposes a stapler with tactile feedback, which detects tissue characteristics through a pressure sensor and provides tactile cues. However, this patent does not disclose a specific cutting force calculation model, and its feedback mechanism is more inclined to prompt the user rather than automatically adjust the device parameters. In addition, there is no non-linear force calculation method that combines tissue thickness with motor dynamic parameters in the prior art. Especially in the field of handheld or electric staplers, an accurate control scheme for lightweight hardware is still blank.

[0007] From a hardware perspective, electric linear cutting staplers usually use a microcontroller (such as the STM32 series) as the core processor, and its computing power and power consumption are limited. Existing complex algorithms (such as neural network-based force prediction) require high-performance computing resources in the training and inference stages, which are obviously not suitable for the embedded environment of such devices. Therefore, developing a control method that can accurately calculate the cutting force and operate under low computing power has become the focus and difficulty of current research.

[0008] In summary, the cutting force control technology of existing electric linear cutting staplers has the following deficiencies: First, there is a lack of a real-time and accurate cutting force calculation model, especially a method that can reflect the non-linear characteristics of tissues; second, key variables such as tissue thickness are not fully integrated, resulting in a single control strategy; third, existing feedback mechanisms mainly focus on stapling optimization and ignore the fine management of the cutting process; fourth, there is a lack of lightweight algorithm design for handheld devices. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to overcome the deficiencies of the prior art and provide a control method for the cutting force of an electric linear cutting stapler. This method calculates the cutting force in real time through a non-linear exponential correction model, combines tissue thickness and motor parameters to judge tissue types, dynamically adjusts the cutting speed, and achieves efficient operation under low computing power, improving the safety and accuracy of surgery.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A control method for the cutting force of an electric linear cutting stapler, comprising the following steps:

[0012] Real-time collect the current I(t), rotational speed ω(t) of the motor, and tissue thickness d(t), where d(t) is measured by ultrasonic waves;

[0013] Use a non-linear exponential correction model to calculate the real-time cutting force F c (t), and the calculation formula is:

[0014] F c (t) = k·I(t)·e α·d(t) -b·ω(t) 2

[0015] where k is the current proportionality coefficient, α is the tissue thickness influence factor, and b is the rotational speed influence coefficient;

[0016] Judge the tissue type according to F c (t), and the specific rule is:

[0017] If F c (t) < F soft , it is determined as soft tissue;

[0018] If F soft ≤F c (t) < F hard , it is determined as medium-hard tissue;

[0019] If F c (t)≥F hard , it is determined as hard tissue;

[0020] According to the tissue type and the value of Fc(t), dynamically adjust the cutting speed v(t), and the specific adjustment rule is:

[0021] If the tissue is soft tissue, then v(t) = v normal ;

[0022] If the tissue is medium-hard tissue, then v(t) = v normal ×0.8;

[0023] If the tissue is hard tissue, then v(t) = v slow ;

[0024] When F c (t) < F complete , and the duration exceeds the preset time, stop the cutting operation.

[0025] Further, the parameters k, α, and b in the non-linear exponential correction model are obtained through experimental calibration, where the range of k is 0.5 - 0.8 N / A, the range of α is 0.1 - 0.3 mm -1 , and the range of b is 0.0004 - 0.0006 N / (rad / s) 2 .

[0026] Further, the tissue thickness d(t) is measured by ultrasonic waves, the measurement frequency is not lower than 50 Hz, and the resolution is not lower than 0.2 mm.

[0027] Further, the cutting force threshold F soft is set to 2.5 N, F hard is set to 6 N, F complete is set to 0.5 N.

[0028] Further, the adjustment of the cutting speed v(t) also includes: when F c (t) is between F soft and F hard , linear interpolation is used to calculate v(t):

[0029]

[0030] Further, when F c (t) > F max , cutting is stopped and an alarm is triggered, where F max is set to 12 N.

[0031] Further, the acquisition frequency of the current I(t) and the rotational speed ω(t) is not lower than 100 Hz, and they are processed by a low-pass filter to reduce noise interference, and the cut-off frequency of the filter is 10 Hz.

[0032] Further, according to the Fc(t) data after each cutting, the values of k and b are updated using the moving average method, and the update formula is:

[0033]

[0034] where β is the update weight, and the value range is 0.05 - 0.1.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1. By monitoring motor parameters (such as current and rotational speed) and tissue thickness, and combining with the non-linear exponential correction model, the present invention accurately calculates the cutting force and dynamically adjusts the cutting speed according to the changes in tissue characteristics. This real-time feedback mechanism effectively avoids tissue damage caused by excessive cutting force or incomplete cutting caused by insufficient cutting force, thus significantly enhancing the safety during the surgical process.

[0037] 2. The present invention has a built-in upper limit alarm for cutting force and an automatic stop function. When abnormal cutting force is detected (such as exceeding the preset safety threshold), the system will immediately stop cutting and trigger an alarm. This design can intervene in a timely manner before equipment failures or potential surgical accidents occur, ensuring the safety of patients and surgical staff. By using the moving average method to adjust the model parameters in real time, it is ensured that the algorithm can adapt to different tissue types and individual patient differences. This flexibility reduces the risk of misjudgment caused by fixed parameters, further enhancing the reliability of the surgery.

[0038] 3. The control method of the present invention is computationally simple, only involving basic mathematical operations (such as exponents, squares, and multiplications), and can operate efficiently in an embedded system without the need for high-performance computing resources. This feature reduces the hardware cost and power consumption of the device, making it more practical. By updating the model parameters online, the device can continuously optimize its performance during long-term use and adapt to different surgical scenarios and tissue conditions. This adaptive ability enhances the intelligence level and stability of the device.

[0039] 4. This method is applicable to the cutting of soft tissues, moderately hard tissues, and hard tissues, and realizes safe and efficient operation through dynamic adjustment, covering a variety of surgical application scenarios and having wide adaptability.

[0040] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0042] Figure 1 is a schematic flow chart of the control method for the cutting force of an electric linear cutting stapler in the present invention.

[0043] Figure 2 is a schematic diagram of an electric linear cutting stapler. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0045] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0046] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0047] Please refer to Figures 1-2 , the electric laparoscopic linear cutting stapler is composed of a clamp head execution assembly 1, a gun rod transmission connection assembly 2, and a handle control assembly 3 connected in sequence. The clamp head execution assembly 1 is driven by a motor in the handle control assembly 3 to drive the gun rod transmission connection assembly 2. The control method of its cutting force is as follows:

[0048] A control method for the cutting force of an electric linear cutting stapler includes the following steps:

[0049] Real-time collect the current I(t), rotational speed ω(t) of the motor, and tissue thickness d(t), where the tissue thickness d(t) is measured by ultrasonic waves, the measurement frequency is not less than 50 Hz, the resolution is not less than 0.2 mm, the collection frequencies of the current I(t) and rotational speed ω(t) are not less than 100 Hz, and are processed by a low-pass filter to reduce noise interference, and the cut-off frequency of the filter is 10 Hz.

[0050] Use a non-linear exponential correction model to calculate the real-time cutting force F c(t), the calculation formula is:

[0051] F c (t) = k·I(t)·e α·d(t) -b·ω(t) 2

[0052] Among them, k is the current proportionality coefficient, α is the tissue thickness influence factor, and b is the rotational speed influence coefficient;

[0053] According to F c (t) to judge the tissue type, the specific rules are:

[0054] If F c (t) < F soft , it is determined as soft tissue;

[0055] If F soft ≤F c (t) < F hard , it is determined as medium-hard tissue;

[0056] If F c (t) ≥ F hard , it is determined as hard tissue;

[0057] According to the tissue type and the value of Fc(t), dynamically adjust the cutting speed v(t), the specific adjustment rules are:

[0058] If the tissue is soft tissue, then v(t) = v normal ;

[0059] If the tissue is medium-hard tissue, then v(t) = v normal ×0.8;

[0060] If the tissue is hard tissue, then v(t) = v slow ;

[0061] When F c (t) < F complete , and the duration exceeds the preset time, stop the cutting operation.

[0062] Among them, the parameters k, α, and b in the non-linear exponential correction model are obtained through experimental calibration. Among them, the range of k is 0.5 - 0.8 N / A, the range of α is 0.1 - 0.3 mm -1 , and the range of b is 0.0004 - 0.0006 N / (rad / s) 2 ; The cutting force threshold F soft is set to 2.5 N, F hard is set to 6 N, F complete is set to 0.5 N.

[0063] Among them, the adjustment of the cutting speed v(t) also includes: when F c (t) is between F soft and F hard , linear interpolation is used to calculate v(t):

[0064]

[0065] When F c (t) > F max , cutting is stopped and an alarm is triggered, where F max is set to 12N.

[0066] According to the Fc(t) data after each cut, the values of k and b are updated using the moving average method. The update formula is:

[0067]

[0068] Among them, β is the update weight, and its value range is 0.05 to 0.1.

[0069] Example 1:

[0070] Safety control for soft tissue cutting. Scenario: Cutting intestinal soft tissue during gastrointestinal surgery, with a thickness of approximately 2 mm.

[0071] 1. Data acquisition:

[0072] Initial state: I(t) = 1.2 A, ω(t) = 30 rad / s, d(t) = 2 mm.

[0073] Sampling frequency is 100 Hz, and the data is processed by a low-pass filter (cutoff frequency 10 Hz).

[0074] 2. Cutting force calculation:

[0075] Parameters: k = 0.6 N / A, α = 0.2 mm -1 , b = 0.0005 N / (rad / s) 2 .

[0076] Calculation:

[0077] F c (t) = 0.6 · 1.2 · e 0.2×2 -0.0005·30 2 = 0.0624 N

[0078] 3. Tissue type judgment: F c (t) = 0.624 N < 2.5 N (F soft ), it is determined to be soft tissue.

[0079] 4. Cutting speed adjustment:

[0080] v(t) = v normal = 10 mm / s

[0081] Safety implementation: The soft tissue cutting force is low, maintaining a normal speed to avoid incomplete cutting, and at the same time, real-time monitoring is carried out to ensure that the force does not exceed the safety threshold (12 N).

[0082] 5. Cutting termination:

[0083] When the cutting is completed, F c (t) drops to 0.3 N and lasts for 0.1 second, triggering the stop mechanism to avoid over-cutting and damaging adjacent tissues.

[0084] Safety manifestation: Through a fast response to low cutting force and a real-time termination mechanism, it ensures that soft tissue cutting is not excessive and protects fragile tissue structures.

[0085] Example 2:

[0086] Safety control for cutting medium-hard tissues, scenario: cutting gastric wall tissue with a thickness of about 4 mm.

[0087] 1. Data acquisition: I(t) = 3 A, ω(t) = 50 rad / s, d(t) = 4 mm.

[0088] 2. Cutting force calculation:

[0089] F c (t) = 0.6·3·e 0.2×4 -0.0005·50 2 = 2.755 N

[0090] 3. Tissue type judgment: 2.5 N < F c (t) < 6 N, determined as medium-hard.

[0091] 4. Cutting speed adjustment: v(t) = v normal ×0.8 = 10×0.8 = 8 mm / s;

[0092] Safety implementation: By reducing the speed, the impact force of the blade on the tissue is reduced to avoid tearing, and at the same time, linear interpolation is used to smooth the speed change:

[0093]

[0094] 5. Full monitoring: If F c (t) suddenly increases to 12 N, immediately stop and trigger the buzzer alarm (1 kHz, 1 second).

[0095] Example 3:

[0096] Safety control for cutting hard tissues, scenario: cutting scar tissue with a thickness of about 6 mm.

[0097] 1. Data acquisition: I(t) = 4A, ω(t) = 40rad / s, d(t) = 6mm

[0098] 2. Cutting force calculation:

[0099] F c (t) = 0.6·4·e 0.2×6 -0.0005·40 2 = 7.168N

[0100] 3. Tissue type judgment: F c (t) = 7.168N > 6N, determined as hard tissue.

[0101] 4. Cutting speed adjustment: v(t) = v slow = 5mm / s;

[0102] 5. Abnormality handling: If I(t) increases to 5A during cutting, F c (t) = 9.96N, still safe. If I(t) increases to 7A during cutting, F c (t) = 13.94N is greater than 12N, immediately stop and alarm.

[0103] Example 4: Parameter adaptive adjustment

[0104] Scenario: Update parameters after continuous cutting.

[0105] If F c (t) = 2N, I(t) = 2A, ω(t) = 50rad / s, d(t) = 3mm, update k:

[0106]

[0107] The present invention accurately calculates the cutting force by monitoring motor parameters (such as current and rotational speed) and tissue thickness, and dynamically adjusts the cutting speed according to the changes in tissue characteristics. This real-time feedback mechanism effectively avoids tissue damage caused by excessive cutting force or incomplete cutting caused by insufficient cutting force, thus significantly enhancing the safety during the surgical process.

[0108] Moreover, with a built-in cutting force upper limit alarm and automatic stop function, when abnormal cutting force is detected (such as exceeding the preset safety threshold), the system will immediately stop cutting and trigger an alarm. This design can intervene in a timely manner before equipment failure or potential surgical accidents occur, ensuring the safety of patients and surgical personnel. The model parameters are adjusted in real time by the moving average method to ensure that the algorithm can adapt to different tissue types and individual patient differences. This flexibility reduces the risk of misjudgment caused by fixed parameters, further improving the reliability of the surgery.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A control method for the cutting force of an electric linear cutting stapler, characterized in that, Including the following steps: Collect the current I(t), rotational speed ω(t) of the motor and tissue thickness d(t) in real time, where d(t) is measured by ultrasonic waves; Calculate the real-time cutting force Fc(t) using a non-linear exponential correction model, and the calculation formula is: F c (t) = k·I(t)·e α·d(t) -b·ω(t) 2 where k is the current proportionality coefficient, α is the tissue thickness influence factor, and b is the rotational speed influence coefficient; Judge the tissue type according to Fc(t), and the specific rule is: If F c (t) < F soft , it is determined to be soft tissue; If F soft ≤ F c (t) < F hard , it is determined as a medium-hardness structure; If F c (t) ≥ F hard , it is determined to be soft tissue; Dynamically adjust the cutting speed v(t) according to the tissue type and the value of Fc(t), and the specific adjustment rule is: If the tissue is soft tissue, then v(t) = v normal ; If the tissue is of medium hardness, then v(t) = v normal × 0.8; If the tissue is hard tissue, then v(t) = v slow ; When F c (t) < F complete and the duration exceeds a preset time, stop the cutting operation.

2. The control method for the cutting force of the electric linear cutting stapler according to claim 1, wherein: The parameters k, α, and b in the non-linear exponential correction model are obtained through experimental calibration, where the range of k is 0.5 - 0.8 N / A, the range of α is 0.1 - 0.3 mm -1 , and the range of b is 0.0004 - 0.0006 N / (rad / s) 2 .

3. The control method for the cutting force of the electric linear cutting stapler according to claim 1, characterized in that: The tissue thickness d(t) is measured by ultrasonic waves, the measurement frequency is not less than 50Hz, and the resolution is not less than 0.2mm.

4. The control method for the cutting force of the electric linear cutting stapler according to claim 1, wherein: Cutting force threshold F soft is set to 2.5 N, F hard is set to 6 N, F complete is set to 0.5 N.

5. The control method for the cutting force of the electric linear cutting stapler according to claim 1, characterized in that: The adjustment of the cutting speed v(t) also includes: when F c (t) is between F soft and F hard , linearly interpolate to calculate v(t):

6. The control method for the cutting force of the electric linear cutting stapler according to claim 1, characterized in that: When F c (t) > F max stop cutting and trigger an alarm, where F max is set to 12 N.

7. The control method for the cutting force of the electric linear cutting stapler according to claim 1, wherein: The acquisition frequency of the current I(t) and the rotational speed ω(t) is not less than 100Hz, and is processed by a low-pass filter to reduce noise interference, and the cut-off frequency of the filter is 10Hz.

8. The control method for the cutting force of the electric linear cutting stapler according to claim 1, characterized in that: According to the Fc(t) data after each cutting, update the values of k and b using the moving average method, and the update formula is: where β is the update weight, and the value range is 0.05 to 0.1.

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