A method for testing the life of a wire transmission system of a minimally invasive surgical instrument

Abstract

The present invention relates to the field of transmission wire fatigue life assessment, specifically a method for testing the life of a wire transmission system for a minimally invasive surgical instrument (MISI). The method is based on the characteristic that the transmission wire to be tested breaks after bending fatigue, resulting in a reduction in the cross-sectional area of ​​the transmission wire to be tested, a change in resistance, and a change in the current in the circuit. By constructing a measurement circuit for the transmission wire to be tested and detecting the cross-sectional area of ​​the transmission wire to be tested within the measurement circuit, the number of broken wires in the transmission wire to be tested is estimated, thereby implementing a life test for the wire transmission system of a minimally invasive surgical instrument. Compared to traditional manual counting methods, the present invention automates the broken wire calculation process and life test process, and has lower cost and more accurate calculation accuracy. The method is suitable for bending fatigue life testing of pulley transmission systems using small-diameter (less than 1 mm) transmission wires in medical devices.

Description

Technical Field

[0001] The present invention relates to the field of transmission wire fatigue life assessment, and specifically to a method for testing the life of a minimally invasive surgical instrument (MISI) wire transmission system. The method is suitable for bending fatigue life testing of a pulley transmission system using a small diameter (less than 1 mm) transmission wire in medical devices. Background Art

[0002] Transmission wire ropes offer advantages such as flexibility, high strength, and low cost, making them widely used in machinery, aerospace, marine, medical, and other fields requiring transmission over long distances and in a small volume. The MISI wire transmission system is a sheave structure consisting of a transmission wire and pulleys. The wire drive drives the joints through the wire drive, completing operations such as shearing and suturing during minimally invasive surgery. During use, the MISI transmission wire undergoes repeated stretching and bending, causing fatigue. Postoperative cleaning and disinfection also accelerates wear and aging of the transmission wire. Fatigue failure of the transmission wire can cause major accidents such as equipment damage and casualties. Therefore, life testing of the transmission wire is of great significance.

[0003] The national standard GB / T 12347-2008, Testing Method for Steel Wire Rope Bending Fatigue, stipulates that test parameters should be selected in accordance with the relevant product standards or technical requirements. Tension can be applied to the specimen using a mechanical or weighted load, with an allowable deviation of ±3%. The test is terminated when the number of broken wires within one lay length reaches the specified value. To verify that the MISI's transmission wire life meets the experimental requirements of this national standard, bending fatigue testing is also required.

[0004] Chinese patent application number CN202022464294.7 discloses a small-diameter wire drive bending fatigue life test device. This device uses a switching ring and disc to change the test wheel wrap angle, and a counting device to detect wire breakage. The test method used by this device has the following problems:

[0005] 1. No other parameters except the wrap angle are introduced, and it is impossible to explore the impact of changes in other MISI parameters on life;

[0006] 2. The actual working conditions of MISI cannot be restored during the test process, resulting in a large gap between the test life and the actual life;

[0007] 3. The counting device is greatly affected by the test environment and the counting accuracy is low. Summary of the Invention

[0008] In view of this, the present invention proposes a testing method for the life of the wire transmission system of minimally invasive surgical instruments to solve the problems that the existing testing methods cannot restore the actual working conditions of MISI, the test parameters are single, and the broken wire counting is not stable and has low accuracy.

[0009] The present invention adopts the following technical solutions:

[0010] A method for testing the life of a wire transmission system of a minimally invasive surgical instrument is applicable to a life testing system comprising a bending fatigue generating device, a measuring device, and a data analysis and processing unit. The bending fatigue generating device comprises a pulley structure and a transmission wire to be tested, and the data analysis and processing unit comprises a counting unit and a computing unit. The testing steps include:

[0011] Step 1: Set various parameter values ​​of the bending fatigue generating device according to the test requirements and initialize the counter to zero; build a measurement loop for the sensor wire to be tested;

[0012] Step 2: Start the bending fatigue generating device to make the transmission wire to be tested perform periodic reciprocating motion between the test wheels to generate bending fatigue, and use a calculator to count the test cycles and wire breakages at the same time;

[0013] Step 3: collecting current data flowing through the transmission wire to be tested when the bending fatigue generating device is running, the current data is the current data of the transmission wire to be tested in the measurement loop obtained by using the measuring device;

[0014] Step 4: The calculation unit calculates the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit according to the current data obtained in step 3 using the following formula:

[0015]

[0016] Where S is the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit, U is the preset DC power supply voltage, ρ is the resistivity of the transmission wire to be measured, and L is the length of the transmission wire to be measured in the measurement circuit. To measure the current data of the transmission wire to be tested in the circuit;

[0017] Step 5: When the cross-sectional area obtained in step 4 reaches the preset threshold, the counter stops counting and counts the test cycles and the number of broken wires, completing the life test of the wire transmission system of the minimally invasive surgical instrument.

[0018] Furthermore, the method for constructing the measurement loop in step 1 includes:

[0019] Install a wire clamp on the transmission wire to be tested. The installation position of the wire clamp should meet the following requirements: the contact area between the transmission to be tested and the sheave structure is placed inside the loop, and the distance from the test wheel is greater than or equal to 3cm;

[0020] Use a DC power supply as a voltage device, connect the wire clamps to the DC power supply and the measuring device respectively, and form a loop.

[0021] Furthermore, the measuring device is a high-precision ammeter.

[0022] Furthermore, the test cycle of step 2 is set according to the demand. Each test cycle is 4 seconds long, including a dynamic cycle and a static cycle. The bending fatigue generating device works for 3 seconds in a dynamic cycle. After a dynamic cycle, the bending fatigue device stops for 1 second and enters the dynamic cycle of the next test cycle. The measuring device collects the current value I of the ammeter every 0.2 seconds in the static cycle. i , i is the number of sampling times, calculate the average of five current values ​​in a static period It is used as the current data of the transmission wire to be tested in the measurement circuit during the test cycle.

[0023] Furthermore, the data analysis and processing unit is also provided with a data storage function, which is used to interrupt the test process and save the current parameter information and test data when a fault occurs during the test.

[0024] After adopting the above technical solution, the present invention has the following advantages:

[0025] 1. When the transmission wire to be tested suffers bending fatigue and breaks, the cross-sectional area of ​​the transmission wire to be tested will be reduced, and the resistance will change, thereby changing the current in the circuit. Based on this feature, the method of the present invention estimates the number of broken wires by constructing a measurement circuit and detecting the cross-sectional area of ​​the transmission wire to be tested in the measurement circuit. Compared with manual counting, the cost is lower, the calculation result is more accurate and reliable, and the broken wire calculation process and life test process are automated.

[0026] 2. The present invention restores the actual working conditions of MISI in the test, sets the parameter values ​​of the bending fatigue generating device according to the test requirements, and realizes the life test of the wire transmission under different working conditions. The method is simple, easy to operate, and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the overall structure of a bending fatigue generating device selected from the embodiment;

[0028] Figure 2 This is a test flow chart of a method for testing the life of a wire transmission system of a minimally invasive surgical instrument according to an embodiment;

[0029] Reference numerals:

[0030] 1. Drive module; 2. Load module; 3. Parameter adjustment module; 4. Test platform. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0032] The present embodiment provides a method for testing the life of a wire transmission system of a minimally invasive surgical instrument, which is applicable to a life testing system having a bending fatigue generating device, a measuring device, and a data processing unit.

[0033] The structure of the bending fatigue generating device selected in this embodiment is as follows Figure 1 As shown, it includes a driving module, a parameter adjustment module and a load module; the driving module is responsible for driving the transmission wire to be tested to perform periodic reciprocating motion; the parameter adjustment module is responsible for changing the parameter values ​​of the sheave angle, sheave inclination and slack length in the sheave structure within the product standard range; the load module is responsible for providing and adjusting the tension for the transmission wire to be tested. Before the test, the bending fatigue generating device is first fixedly installed on the test platform, and each end of the transmission wire to be tested is fixed or wrapped in the designated area of ​​the bending fatigue generating device. Then follow the steps below to complete the test of the life of the wire transmission system of minimally invasive surgical instruments. The test implementation process is as follows: Figure 2 Shown, including:

[0034] Step 1: Set the various parameter values ​​of the bending fatigue generating device according to the test requirements, such as the sheave angle, sheave inclination, and slack length, and initialize the counter to zero; and construct a measurement loop for the sensor wire to be tested. In this embodiment, the various parameter values ​​of the bending fatigue generating device are set by the parameter adjustment mode and the load. The method for constructing the measurement loop is as follows:

[0035] Install a wire clamp on the transmission wire to be tested. The wire clamp should be positioned so that the contact area between the transmission wire to be tested and the sheave structure is within the loop and at least 3 cm from the test wheel. Use a DC power supply as the voltage source, and connect the wire clamp to the DC power supply and the measuring device, forming a loop. In this example, a high-precision ammeter is used as the measuring device.

[0036] Step 2: Start the bending fatigue generator to cause the transmission wire to undergo periodic reciprocating motion between the test wheels, generating bending fatigue. Simultaneously, a calculator is used to count the test cycles and wire breakage. The test cycle is set as required. Each test cycle is 4 seconds long and includes a dynamic period and a static period. The bending fatigue generator operates for 3 seconds during a dynamic period. After a dynamic period, the bending fatigue generator remains stationary for 1 second before entering the dynamic period of the next test cycle.

[0037] Step 3: Collect current data flowing through the transmission wire under test while the bending fatigue generator is operating. This current data is obtained using a measuring device. The measuring device collects current from the ammeter every 0.2 seconds during the static period, where i is the number of samples. The average of the five current values ​​during the static period is calculated as the current data for the transmission wire under test within the measurement loop for the test period.

[0038] Step 4: The calculation unit calculates the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit according to the current data obtained in step 3 using the following formula:

[0039]

[0040] Where S is the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit, U is the preset DC power supply voltage, ρ is the resistivity of the transmission wire to be measured, and L is the length of the transmission wire to be measured in the measurement circuit. To measure the current data of the transmission wire to be tested in the circuit;

[0041] Step 5: When the cross-sectional area obtained in Step 4 reaches the preset threshold, the counter stops counting and counts the test cycles and the number of broken wires, completing the life test of the wire drive system of the minimally invasive surgical instrument. The solid arrows in the figure indicate the winding sequence of the transmission wire under test, the dashed arrows indicate the current flow within the loop, and the hollow arrows indicate the direction of control signal transmission.

[0042] During implementation, life test systems inevitably experience malfunctions. Therefore, this embodiment also includes a data storage unit within the test data analysis and processing unit. The data storage unit is used to obtain parameter information and test data for the current test cycle and, in the event of a test malfunction or interruption, to store the current parameter information and test data.

[0043] In summary, the test method for the life of the wire transmission system of minimally invasive surgical instruments provided in this embodiment restores the actual working conditions of MISI during the test, solves the problems of single test parameters, unstable counting and low accuracy, and can perform wire transmission life tests under different working conditions.

[0044] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for testing the life of a wire transmission system of a minimally invasive surgical instrument, applicable to a life testing system comprising a bending fatigue generating device, a measuring device, and a data analysis and processing unit; the bending fatigue generating device is provided with a pulley structure and a transmission wire to be tested, and the data analysis and processing unit is composed of a counting unit and a computing unit, characterized in that: The test method includes the following steps: Step 1: Set various parameter values ​​of the bending fatigue generating device according to the test requirements and initialize the counter to zero; build a measurement loop for the sensor wire to be tested; Step 2: Start the bending fatigue generating device to make the transmission wire to be tested perform periodic reciprocating motion between the test wheels to generate bending fatigue, and use a calculator to count the test cycles and wire breakages at the same time; Step 3: collecting current data flowing through the transmission wire to be tested when the bending fatigue generating device is running, the current data is the current data of the transmission wire to be tested in the measurement loop obtained by using the measuring device; Step 4: The calculation unit calculates the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit according to the current data obtained in step 3 using the following formula: Where S is the cross-sectional area of ​​the transmission wire to be measured in the measurement circuit, U is the preset DC power supply voltage, ρ is the resistivity of the transmission wire to be measured, and L is the length of the transmission wire to be measured in the measurement circuit. To measure the current data of the transmission wire to be tested in the circuit; Step 5: When the cross-sectional area obtained in step 4 reaches the preset threshold, the counter stops counting and counts the test cycles and the number of broken wires, completing the life test of the wire transmission system of the minimally invasive surgical instrument.

2. A method for testing the life of a wire transmission system of a minimally invasive surgical instrument according to claim 1, characterized in that: The method for constructing the measurement loop in step 1 includes: Install a wire clamp on the transmission wire to be tested. The installation position of the wire clamp should meet the following requirements: the contact area between the transmission to be tested and the sheave structure is placed inside the loop, and the distance from the test wheel is greater than or equal to 3cm; Use a DC power supply as a voltage device, connect the wire clamps to the DC power supply and the measuring device respectively, and form a loop.

3. The method for testing the life of a wire transmission system of a minimally invasive surgical instrument according to claim 1, characterized in that: The measuring device is a high-precision ammeter.

4. The method for testing the life of a wire transmission system of a minimally invasive surgical instrument according to claim 1, characterized in that: The test cycle of step 2 is set according to the demand. Each test cycle is 4 seconds long, including a dynamic cycle and a static cycle. The bending fatigue generating device works for 3 seconds in a dynamic cycle. After a dynamic cycle, the bending fatigue device stops for 1 second and enters the dynamic cycle of the next test cycle. The measuring device collects the current value I of the ammeter every 0.2 seconds in the static cycle. i , i is the number of sampling times, calculate the average of five current values ​​in a static period It is used as the current data of the transmission wire to be tested in the measurement circuit during the test cycle.

5. A method for testing the life of a wire transmission system of a minimally invasive surgical instrument according to any one of claims 1 to 4, characterized in that: The data analysis and processing unit is also equipped with a data storage function, which is used to interrupt the test process and save the current parameter information and test data when a fault occurs during the test.

Images