Prosthetic knee joint dynamic performance testing machine and testing method

Abstract

The invention discloses an artificial limb knee joint dynamic performance testing machine and method, and the machine comprises a pedestal, a left lifting cylinder disposed at the left edge of the upper surface of the pedestal, a right lifting cylinder disposed at the right edge of the upper surface of the pedestal, a left vertical column disposed on the pedestal at the right side of the left lifting cylinder, and a right vertical column disposed on the pedestal at the left side of the right lifting cylinder. The upper clamp and the lower clamp are used for clamping the knee joint to be tested; a cross beam capable of moving up and down is arranged on the left stand column and the right stand column, the left end and the right end of the cross beam are connected with the upper ends of telescopic rods of the left lifting cylinder and the right lifting cylinder respectively, an electro-hydraulic servo loading device is arranged on the cross beam, and the tail end of a piston rod of the electro-hydraulic servo loading device is connected with an upper clamp through a force sensor. A universal rotating head is arranged in the fixed seat and is connected with a clamp below the universal rotating head through a stud; the device has the advantages of being good in structural stability, high in reliability, capable of working continuously for a long time, capable of improving the test efficiency and high in test precision.

Description

Technical Field

[0001] The present invention relates to the technical field of rehabilitation engineering, and in particular to a prosthetic knee joint dynamic performance testing machine and a testing method thereof. Background Art

[0002] As of 2023, the total number of people with various disabilities in China exceeds 85.914 million. Among them, the number of people with limb disabilities has reached 35.8 million, the number of amputees is about 2 million, and the number of lower limb amputees accounts for 85% of the total number of amputees. In recent years, due to the influence of factors such as diseases, traffic accidents, work injuries, and natural disasters, the number of thigh amputations has been increasing year by year, greatly increasing the social burden.

[0003] Wearing a prosthetic knee joint is the most effective and convenient solution to restore the normal walking ability of lower limb amputees.

[0004] Before a prosthetic knee joint is put into commercial use, performance tests need to be carried out to verify whether the performance meets the design requirements and reaches the national standards.

[0005] Existing prosthetic knee joint tests rely on human tests, but human tests have many defects:

[0006] The number of human test samples is limited. In order to obtain sufficient valid data, subjects need to repeat a single action for a long time, which places too high requirements on the subjects;

[0007] Before the test, a large amount of adaptive training needs to be carried out on the subjects, and a customized prosthetic socket needs to be designed for the subjects, resulting in low efficiency;

[0008] Human tests are affected by the subjective factors of the subjects and lack objectivity and repeatability. Summary of the Invention

[0009] The invention objective of the present invention is to overcome the deficiencies of the prior art and provide a prosthetic knee joint dynamic performance testing machine and a testing method thereof.

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

[0011] A prosthetic knee joint dynamic performance testing machine, comprising a base, a left lifting cylinder provided at the left edge of the upper surface of the base, a right lifting cylinder provided at the right edge of the upper surface of the base, a left upright column provided on the base to the right of the left lifting cylinder, a right upright column provided on the base to the left of the right lifting cylinder, an upper fixture and a lower fixture for clamping the prosthetic knee joint to be tested; a cross beam that can move up and down is provided on the left and right upright columns, the left and right ends of the cross beam are respectively connected to the upper ends of the telescopic rods of the left lifting cylinder and the right lifting cylinder, an electro-hydraulic servo loading device is provided on the cross beam, the end of the piston rod of the electro-hydraulic servo loading device is connected to the upper fixture through a force sensor, a fixed seat is provided in the middle of the upper surface of the base, a universal rotating head is provided in the fixed seat, and the universal rotating head is connected to the lower fixture through a stud; the electro-hydraulic servo loading device includes a hydrostatic servo cylinder, a displacement sensor provided on the piston rod, an electro-hydraulic servo valve and a PID control unit, the electro-hydraulic servo valve is connected to the hydrostatic servo cylinder, and the electro-hydraulic servo valve and the PID control unit are electrically connected; it also includes an industrial control computer and a measuring and controlling instrument, the measuring and controlling instrument is respectively electrically connected to the force sensor, the displacement sensor and the PID control unit, and the PID control unit is electrically connected to the displacement sensor.

[0012] The base provides the stability of the entire testing machine. The left and right lifting cylinders are used to lift and lower the cross beam. The left and right upright columns provide guidance for the lifting of the cross beam, facilitating the installation and disassembly of the prosthetic knee joint; the prosthetic knee joint is fixed between the upper and lower fixtures, and the universal rotating head can adapt to the rotation of the prosthetic knee joint, which not only meets the stability of clamping but also meets the rotation requirements of the prosthetic knee joint; the piston rod of the electro-hydraulic servo loading device drives the upper fixture to move through the force sensor, thereby applying and releasing force to the prosthetic knee joint; therefore, the structure of the present invention is stable and reliable, easy to operate, and convenient for repeated tests.

[0013] The present invention uses an electro-hydraulic servo loading device to conduct a mechanical performance simulation test on the prosthetic knee joint, and can perform dynamic and static detections on most lower limb prosthetic knee joints already on the market in accordance with the standard GB / T 18375. It can automatically collect test data during the test process according to the test conditions, simplify the test process, and improve the test efficiency.

[0014] It can work continuously for a long time, can conveniently obtain various test data, can avoid the influence of subjective factors of the subjects; it can simulate the test conditions of different populations and various working conditions.

[0015] Preferably, the end of the piston rod is inserted into a flange with a bushing. Left and right vertical guide rods are respectively provided on the left and right parts of the flange. Both the left and right vertical guide rods are slidably connected to the cross beam; a left baffle is provided at the upper end of the left vertical guide rod, and a right baffle is provided at the upper end of the right vertical guide rod; the force sensor is connected to the flange through bolts.

[0016] The left vertical guide rod and the right vertical guide rod provide guidance for the up-and-down movement of the flange, thereby reducing the left-and-right jitter during the test and making the test data more accurate.

[0017] Preferably, the structures of the lower fixture and the upper fixture are the same. The lower fixture includes a lower strip plate, a lower vertical hole provided in the left part of the lower strip plate, and a lower strip hole extending along the length direction provided on the right side of the lower vertical hole; a lower scale is provided on the front outer surface of the lower strip plate corresponding to the length direction of the lower strip hole; the lower end of the prosthetic knee joint is inserted into the lower vertical hole, and a lower bolt that can pass through the lower vertical hole and the lower end of the prosthetic knee joint is provided on the lower strip plate.

[0018] The lower scale is used to view the connection position when clamping the prosthetic knee joint. The connection positions of the lower ends of prosthetic knee joints of different models with the lower strip hole are different.

[0019] The lower stud connected to the universal rotating head extends into the lower strip hole, and a lower locking screw provided on the lower strip hole presses and locks the lower stud.

[0020] The upper fixture includes an upper strip plate, an upper vertical hole provided in the left part of the upper strip plate, and an upper strip hole extending along the length direction provided on the right side of the upper vertical hole; an upper scale is provided on the front outer surface of the upper strip plate corresponding to the length direction of the upper strip hole; the upper end of the prosthetic knee joint is inserted into the upper vertical hole, and an upper bolt that can pass through the upper vertical hole and the upper end of the prosthetic knee joint is provided on the upper strip plate. The lower part of the flange is provided with an upper universal rotating head, and the upper stud connected to the upper universal rotating head extends into the upper strip hole, and an upper locking screw provided on the upper strip hole presses and locks the upper stud.

[0021] The upper scale is used to view the connection position when clamping the prosthetic knee joint. The connection positions of the upper ends of prosthetic knee joints of different models with the upper strip hole are different.

[0022] Preferably, the upper ends of the left column and the right column are connected by a U-shaped horizontal connecting rod.

[0023] A test method for a prosthetic knee joint dynamics performance testing machine includes a static verification test:

[0024] Step 5-1, fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture, and set the set test force F on the industrial control computer SET loading curve, stable test force F STAB loading curve, F SP loading curve and F SP unloading curve;

[0025] Step 5-2, apply the test force F to the prosthetic knee joint SET , so that F SET is at 0.8F C and hold for 30 s and then remove:

[0026] Step 5-2-1, the industrial control computer samples the F SET loading curve and the signal detected by the force sensor at the same frequency to obtain the target loading force F SET_K1 and the actual loading force F K1 at the current moment; the initial value of K1 is 1; a PID controller and a linear iterative controller are provided in the industrial control computer, and both the PID controller and the linear iterative controller are software modules;

[0027] Step 5-2-2, the industrial control computer calculates the error e K1 : e K1 = F SET_K1 - F K1 ;

[0028] The PID controller calculates x K1 :

[0029]

[0030] where e0 = 0, x K1 represents the output value of the PID controller at the K1-th sampling, K P1 is the set proportional coefficient of the PID controller, K I1 is the set integral coefficient of the PID controller, K D1 is the set differential coefficient of the PID controller;

[0031] Step 5-2-3, the linear iterative controller calculates the error compensation term Δx K1 :

[0032] Δx K1 = Δx K1-1 + Γ·e K1-1 ;

[0033] where Γ is the learning gain matrix and Δx1 = 0;

[0034] XXmax is provided in the industrial control computer, and calculate

[0035]

[0036] When |x cmd_K1 | ≤ XXmax, the industrial control computer outputs x cmd_K1 to the PID control unit;

[0037] Step 5-2-4, the PID control unit samples the x cmd_K1 transmitted by the industrial control computer to the PID control unit and the signal detected by the position sensor to obtain the target displacement z K2 of the piston rod of the hydrostatic servo cylinder and the current actual displacement z KK2 ; where the initial value of K2 is 1, zK2 = x cmd_K1 ;

[0038] Step 5-2-5, the PID control unit calculates the error E K2 :

[0039] E K2 = z K2 - z KK2 ;

[0040] The PID control unit performs PID operation:

[0041]

[0042] where y K2 represents the output value of the PID control unit at the K2th sampling of the PID control unit, K P2 is the set proportional coefficient of the PID control unit, K I2 is the set integral coefficient of the PID control unit, K D2 is the set inner-loop differential coefficient of the PID control unit;

[0043] Step 5-2-6, YYmax is set in the PID control unit. When |y K2 | ≤ YYmax, the PID control unit delivers y K2 to the electro-hydraulic servo valve;

[0044] Increase the value of K2 by 1. The PID control unit samples the x cmd_K1 sent by the industrial control computer to the PID control unit and the signal detected by the position sensor, and obtains the target displacement z K2 of the piston rod of the hydrostatic servo cylinder and the current actual displacement z KK2 ; Return to Step 5-2-5;

[0045] Step 5-2-7, the electro-hydraulic servo valve controls the lifting of the piston rod and the amplitude of the lifting according to y K2 ; When the force detected by the force sensor < 0.8F C , increase the value of K1 by 1. The industrial control computer continues to sample the F SET loading curve and the signal detected by the force sensor at the same frequency, and obtains the target loading force F SET_K1 at the current moment and the actual loading force F K1 ; Return to Step 5-2-2;

[0046] When the force detected by the force sensor = 0.8F C , the industrial control computer controls the electro-hydraulic servo valve through the PID control unit, and the electro-hydraulic servo valve controls the piston rod to remain stationary at the current position for 30 s;

[0047] Step 5-2-8: Repeat steps 5-2-1 to 5-2-7, using the set test force F SET Unloading curve: Gradually release the force applied to the prosthetic knee joint

[0048] Using step 5-2, apply the stable test force F STAB Loading curve: Load the force detected by the force sensor to F STAB , and record the displacement L1 detected by the displacement sensor at this time

[0049] Using step 5-2, with an F loading curve having a slope of 100 N / s - 250 N / s SP Loading curve: Smoothly load the force detected by the force sensor from F STAB To the set test force F SP , and hold for 30 seconds

[0050] Using step 5-2, with an F unloading curve having a slope of 100 N / s - 250 N / s SP Unloading curve: Smoothly reduce the force detected by the force sensor from F SP To F STAB , and record the displacement L2 detected by the displacement sensor at this time

[0051] The industrial control computer calculates the deformation amount D:

[0052] D = L2 - L1

[0053] If the deformation amount D ≤ 15 mm, it is determined that the prosthetic knee joint passes the static verification test, and D is output; the static verification test ends

[0054] The present invention selects an electro-hydraulic servo loading device as the actuator, which can meet the requirements of high precision and fast response, and adopts a double-loop PID controller for cyclic control

[0055] The PID controller and the linear iterative controller of the outer loop are responsible for tracking the desired force signal (force loading curve or force unloading curve). The force signal sampling rate is low, and the steady-state error is eliminated through integration and linear iteration to improve the control accuracy of the test loading force. The inner loop control adopts a PID control unit, which receives the position correction instruction output by the outer loop, has a high sampling rate and a fast response speed, and quickly responds to position adjustment. At the same time, the disturbances during the loading process (such as sudden changes in the friction force of the prosthetic knee joint) are first suppressed by the inner loop and will not be directly transmitted to the outer loop, thereby reducing the influence on the outer loop tracking; the double-loop PID controller can improve the dynamic response ability through the division of labor and cooperation between the inner and outer loops, and meet the control objectives of high precision and high response speed at the same time; the inner and outer loops are dynamically decoupled, and the fast response of the inner loop can block the propagation of high-frequency disturbances and reduce the influence on the outer loop, further improving the control accuracy of the outer loop

[0056] Preferably, it further includes a static failure test

[0057] Fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture;

[0058] Set the specified test force F on the industrial control computer SET Loading curve and test force F SU Loading curve;

[0059] Repeat step 5-2, using the test force F SET Loading curve, apply the test force F on the prosthetic knee joint SET , so that F SET At 0.8F C Keep it for 30 s and then remove it;

[0060] Using step 5-2, use the test force F SU Loading curve, load the force detected by the force sensor to F SU , and keep it for 30 seconds;

[0061] If the prosthetic knee joint is not damaged within 30 seconds, it is determined that the prosthetic knee joint meets the requirements of the static failure test, and the static failure test ends.

[0062] Preferably, it further includes a dynamic loading test:

[0063] Step 7-1, fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture;

[0064] Set the specified maximum displacement L, SET The maximum number of force loading times i, SET The maximum number of part replacements n, SET The minimum test force F, MIN Loading curve, test force F C Loading curve and test force F C Unloading curve;

[0065] Step 7-2, using step 5-2, use the minimum test force F MIN Loading curve, apply the minimum test force F on the prosthetic knee joint MIN , the industrial control computer sets the count i1 value of the force loading counter to 0, and the count i2 value of the part replacement counter to 0;

[0066] Step 7-3, using step 5-2, use the test force F C Loading curve, apply the test force F on the prosthetic knee joint C , F C > F MIN , and record the displacement L detected by the displacement sensor at this time, and the industrial control computer increases both the i1 value and the i2 value by 1;

[0067] Step 7-4, if L > L SET , then the industrial control computer makes a judgment that the test sample fails the dynamic loading test;

[0068] If L ≤ L SET , i2 < n SET and i1 < i SET , then use Step 5-2 to use the test force F C to unload the test force F applied to the prosthetic knee joint along the unloading curve C , and return to Step 7-3;

[0069] If L ≤ L SET , i2 ≥ n SET and i1 < i SET , then the industrial control computer makes a judgment that the parts of the prosthetic knee joint need to be replaced. The industrial control computer emits an alarm sound. After the staff hears the alarm sound, they replace the parts of the prosthetic knee joint. After the parts are replaced, the staff gives the industrial control computer a command to continue the test through a button. The industrial control computer sets i2 = 0 and returns to Step 7-3;

[0070] If L ≤ L SET , i2 < n SET and i1 ≥ i SET , then the industrial control computer makes a judgment that the prosthetic knee joint passes the dynamic loading test.

[0071] Therefore, the present invention has the following beneficial effects: good structural stability, high reliability, can work continuously for a long time, is convenient for obtaining various test data, and can avoid the influence of subjective factors of the subject; can simulate test conditions for different populations and various working conditions; simplifies the test process, improves the test efficiency, has high control precision and high test precision. Description of the Drawings

[0072] Figure 1 is a structural schematic diagram of the present invention;

[0073] Figure 2 is a principle block diagram of dual-loop control of the present invention. Detailed Embodiments

[0074] The following further describes the present invention in conjunction with the drawings and specific embodiments.

[0075] As Figure 1The illustrated embodiment is a prosthetic knee joint dynamics performance testing machine, including a base 1, a left lifting cylinder 21 provided at the left edge of the upper surface of the base, a right lifting cylinder 22 provided at the right edge of the upper surface of the base, a left upright column 31 provided on the base to the right of the left lifting cylinder, a right upright column 32 provided on the base to the left of the right lifting cylinder, an upper fixture 10 and a lower fixture 12 for clamping the prosthetic knee joint 6 to be tested; there is a cross beam 4 that can move up and down on the left and right upright columns, the left and right ends of the cross beam are respectively connected to the upper ends of the telescopic rods of the left and right lifting cylinders, an electro-hydraulic servo loading device is provided on the cross beam, the end of the piston rod of the electro-hydraulic servo loading device is connected to the upper fixture through a force sensor 9, a fixed seat 11 is provided in the middle of the upper surface of the base, a universal rotating head is provided in the fixed seat, and the universal rotating head is connected to the lower fixture through a stud; the electro-hydraulic servo loading device includes a hydrostatic servo cylinder 51, a displacement sensor provided on the piston rod, an electro-hydraulic servo valve 52 and a PID control unit, the electro-hydraulic servo valve is connected to the hydrostatic servo cylinder, and the electro-hydraulic servo valve and the PID control unit are electrically connected; it also includes an industrial control computer and a measuring and controlling instrument, the measuring and controlling instrument is respectively electrically connected to the industrial control computer, the force sensor, the displacement sensor and the PID control unit, the PID control unit is electrically connected to the displacement sensor, and it also includes a reversing valve, the reversing valve is respectively electrically connected to the left and right lifting cylinders. The hydraulic pipeline 13 is respectively connected to the electro-hydraulic servo valve and the reversing valve for supplying oil to the left lifting cylinder, the right lifting cylinder and the hydrostatic servo cylinder.

[0076] The end of the piston rod is inserted into a flange 8 with a bushing, and a left vertical guide rod 81 and a right vertical guide rod 82 are respectively provided on the left and right parts of the flange. Both the left vertical guide rod and the right vertical guide rod are slidably connected to the cross beam; a left baffle is provided at the upper end of the left vertical guide rod, and a right baffle is provided at the upper end of the right vertical guide rod; the force sensor is connected to the flange through bolts.

[0077] The structures of the lower fixture and the upper fixture are the same. The lower fixture includes a lower strip plate 121, a lower vertical hole provided in the left part of the lower strip plate, and a lower strip hole 122 extending along the length direction provided to the right of the lower vertical hole; a lower scale is provided on the front outer surface of the lower strip plate corresponding to the length direction of the lower strip hole; the upper fixture includes an upper strip plate, an upper vertical hole provided in the left part of the upper strip plate, and an upper strip hole extending along the length direction provided to the right of the upper vertical hole; an upper scale is provided on the front outer surface of the upper strip plate corresponding to the length direction of the upper strip hole; the lower end of the prosthetic knee joint is inserted into the lower vertical hole, and a lower bolt that can pass through the lower vertical hole and the lower end of the prosthetic knee joint is provided on the lower strip plate; the upper end of the prosthetic knee joint is inserted into the upper vertical hole, and an upper bolt that can pass through the upper vertical hole and the upper end of the prosthetic knee joint is provided on the upper strip plate.

[0078] The upper ends of the left and right upright columns are connected by a U-shaped horizontal connecting rod 7.

[0079] A test method for a prosthetic knee joint dynamics performance testing machine includes a static verification test:

[0080] Step 5-1: Fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture, and set the specified test force F on the industrial control computer. SET Loading curve, stable test force F STAB Loading curve, F SP Loading curve and F SP Unloading curve;

[0081] The operator turns the reversing valve to the left to control the upward movement of the left lifting cylinder and the right lifting cylinder, turns the reversing valve to the right to control the downward movement of the left lifting cylinder and the right lifting cylinder, adjusts the height of the upper fixture, and fixes the upper and lower ends of the prosthetic knee joint to the upper fixture and the lower fixture respectively.

[0082] During the test, the left lifting cylinder and the right lifting cylinder remain stationary.

[0083] Step 5-2: Apply the test force F to the prosthetic knee joint SET , so that F SET is at 0.8F C and hold for 30 s before removing:

[0084] Step 5-2-1: The industrial control computer samples the signals detected by the F SET loading curve and the force sensor at the same frequency to obtain the target loading force F at the current moment SET_K1 and the actual loading force F K1 ; The initial value of K1 is 1; The industrial control computer is equipped with a PID controller and a linear iterative controller, and both the PID controller and the linear iterative controller are software modules;

[0085] Step 5-2-2: The industrial control computer calculates the error e K1 : e K1 = F SET_K1 - F K1 ;

[0086] The PID controller calculates x K1 :

[0087]

[0088] where e0 = 0, x K1 represents the output value of the PID controller for the K1th sampling, K P1 is the set proportional coefficient of the PID controller, K I1 is the set integral coefficient of the PID controller, K D1 is the set differential coefficient of the PID controller;

[0089] Step 5-2-3: The linear iterative controller calculates the error compensation term Δx K1 :

[0090] Δx K1 = Δx K1-1 + Γ·e K1-1 ;

[0091] where Γ is the learning gain matrix and Δx1 = 0;

[0092] XXmax is set in the industrial control computer to calculate

[0093]

[0094] When |x cmd_K1 | ≤ XXmax, the industrial control computer outputs x cmd_K1 to the PID control unit;

[0095] Step 5-2-4, the PID control unit samples the x cmd_K1 transported by the industrial control computer to the PID control unit and the signal detected by the position sensor to obtain the target displacement z K2 of the piston rod of the static pressure servo cylinder and the current actual displacement z KK2 ; where the initial value of K2 is 1 and z K2 = x cmd_K1 ;

[0096] Step 5-2-5, the PID control unit calculates the error E K2 :

[0097] E K2 = z K2 - z KK2 ;

[0098] The PID control unit performs PID operation:

[0099]

[0100] where y K2 represents the output value of the PID control unit at the K2th sampling of the PID control unit, K P2 is the set proportional coefficient of the PID control unit, K I2 is the set integral coefficient of the PID control unit, and K D2 is the set inner loop differential coefficient of the PID control unit;

[0101] Step 5-2-6, YYmax is set in the PID control unit. When |y K2 | ≤ YYmax, the PID control unit transports y K2 to the electro-hydraulic servo valve;

[0102] Increase the value of K2 by 1. The PID control unit processes the x cmd_K1Sample the signals detected by the position sensor to obtain the target displacement z of the piston rod of the static pressure servo cylinder K2 and the current actual displacement z KK2 ; Return to step 5-2-5;

[0103] Step 5-2-7, the electro-hydraulic servo valve controls the lifting and lowering of the piston rod and the amplitude of the lifting and lowering according to y K2 ; When the force detected by the force sensor < 0.8F C , increase the value of K1 by 1, and the industrial control computer continues to sample the F SET loading curve and the signals detected by the force sensor at the same frequency to obtain the target loading force F SET_K1 at the current moment, and the actual loading force F K1 ; Return to step 5-2-2;

[0104] When the force detected by the force sensor = 0.8F C , the industrial control computer controls the electro-hydraulic servo valve through the PID control unit, and the electro-hydraulic servo valve controls the piston rod to remain stationary at the current position for 30 s;

[0105] Step 5-2-8, repeat steps 5-2-1 to 5-2-7, and use the set test force F SET unloading curve to gradually release the force applied to the prosthetic knee joint;

[0106] As Figure 2 shown, the PID controller and the linear iterative controller of the outer loop are responsible for tracking the desired force signal (force loading curve or force unloading curve). The force signal sampling rate is low, and the steady-state error is eliminated through integration and linear iteration to improve the control accuracy of the test loading force. The inner loop control uses a PID control unit to receive the position correction instruction output by the outer loop, with a high sampling rate and fast response speed, and quickly responds to position adjustment. At the same time, the disturbances during the loading process (such as sudden changes in the friction force of the prosthetic knee joint) are first suppressed by the inner loop and will not be directly transmitted to the outer loop, thereby reducing the impact on the outer loop tracking; the tracking filter (a low-pass filter) is used to filter the detected force signal to filter out interference signals. The dual-loop PID controller of the present invention can improve the dynamic response ability through the division of labor and cooperation of the inner and outer loops, each performing its own functions, and at the same time meet the control objectives of high precision and high response speed; the inner and outer loops are dynamically decoupled, and the fast response of the inner loop can block the propagation of high-frequency disturbances and reduce the impact on the outer loop, further improving the control accuracy of the outer loop.

[0107] Using step 5-2, use the stable test force F STAB loading curve to load the force detected by the force sensor to F STAB , and record the displacement L1 detected by the displacement sensor at this time;

[0108] Using step 5-2, with a slope of 100 N / s - 250 N / s for FSP Loading curve, the force detected by the force sensor is smoothly loaded from F STAB to the set test force F SP and maintained for 30 seconds;

[0109] Using step 5-2, with a slope of 100 N / s - 250 N / s for the F SP unloading curve, the force detected by the force sensor is smoothly decreased from F SP to F STAB , and record the displacement L2 detected by the displacement sensor at this time;

[0110] The industrial control computer calculates the deformation D:

[0111] D = L2 - L1;

[0112] If the deformation D ≤ 15 mm, it is determined that the prosthetic knee joint passes the static verification test and output D; the static verification test ends.

[0113] It also includes a static destruction test:

[0114] Fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture;

[0115] Set the set test force F on the industrial control computer SET loading curve and test force F SU loading curve;

[0116] Repeat step 5-2, using the test force F SET loading curve, apply the test force F to the prosthetic knee joint SET so that F SET is at 0.8F C maintained for 30 s and then removed;

[0117] Using step 5-2, use the test force F SU loading curve, load the force detected by the force sensor to F SU and maintain for 30 seconds;

[0118] If the prosthetic knee joint is not damaged within 30 seconds, it is determined that the prosthetic knee joint meets the requirements of the static destruction test and the static destruction test ends.

[0119] It also includes a dynamic loading test:

[0120] Step 7-1, fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture;

[0121] Set the set maximum displacement L SET , maximum force loading times i SET , maximum part replacement times n SET , minimum test force FMIN Loading curve, test force F C Loading curve and test force F C Unloading curve; n SET = 100,000, n SET The value of n is provided by the lower limb prosthesis manufacturer.

[0122] Step 7-2: Using Step 5-2, apply the minimum test force F MIN to the loading curve and apply the minimum test force F to the prosthetic knee joint MIN . The industrial control computer sets the count i1 value of the force loading counter to 0 and the count i2 value of the part replacement counter to 0;

[0123] Step 7-3: Using Step 5-2, apply the test force F C to the loading curve and apply the test force F to the prosthetic knee joint C , and record the displacement L detected by the displacement sensor at this time. The industrial control computer increments both the i1 value and the i2 value by 1;

[0124] Step 7-4: If L > L SET , then the industrial control computer determines that the test sample fails the dynamic loading test;

[0125] If L ≤ L SET , i2 < n SET and i1 < i SET , then using Step 5-2, apply the test force F C to the unloading curve to release the test force F applied to the prosthetic knee joint C , and return to Step 7-3;

[0126] If L ≤ L SET , i2 ≥ n SET and i1 < i SET , then the industrial control computer determines that the parts of the prosthetic knee joint need to be replaced. The industrial control computer emits an alarm sound. After the staff hears the alarm sound, they replace the parts of the prosthetic knee joint. After the parts are replaced, the staff gives the industrial control computer a command to continue the test through a button. The industrial control computer sets i2 = 0 and returns to Step 7-3;

[0127] If L ≤ L SET , i2 < n SET and i1 ≥ i SET , then the industrial control computer determines that the prosthetic knee joint passes the dynamic loading test.

[0128] The test loading forces used in this embodiment are shown in the following table:

[0129] Test force

[0130]

[0131] 1. Test loading condition I is related to the maximum loading value occurring in the initial stage of walking support;

[0132] 2. Test loading condition II is related to the maximum loading value occurring in the later stage of walking support;

[0133] 3. The test load level should be determined by comprehensively considering factors such as the user's body parameters and movement characteristics.

[0134] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A prosthetic knee joint dynamic performance testing machine, characterized in that, It includes a base (1), a left lifting cylinder (21) provided at the left edge of the upper surface of the base, a right lifting cylinder (22) provided at the right edge of the upper surface of the base, a left upright column (31) on the base to the right of the left lifting cylinder, a right upright column (32) on the base to the left of the right lifting cylinder, an upper fixture (10) and a lower fixture (12) for clamping the above-mentioned prosthetic knee joint (6) to be measured; there is a cross beam (4) that can move up and down on the left and right upright columns, the left and right ends of the cross beam are respectively connected to the upper ends of the telescopic rods of the left and right lifting cylinders, and an electro-hydraulic servo loading device is provided on the cross beam. The end of the piston rod of the electro-hydraulic servo loading device is connected to the upper fixture through a force sensor (9). In the middle of the upper surface of the base, there is a fixed seat (11). A universal swivel head is provided in the fixed seat, and the universal swivel head is connected to the lower fixture through a stud; the electro-hydraulic servo loading device includes a hydrostatic servo cylinder (51), a displacement sensor provided on the piston rod, an electro-hydraulic servo valve (52) and a PID control unit. The electro-hydraulic servo valve is connected to the hydrostatic servo cylinder, and the electro-hydraulic servo valve and the PID control unit are electrically connected; it also includes an industrial control computer and a measuring and control instrument. The measuring and control instrument is respectively electrically connected to the industrial control computer, the force sensor, the displacement sensor and the PID control unit, and the PID control unit is electrically connected to the displacement sensor.

2. The prosthetic knee joint dynamics performance testing machine according to claim 1, characterized in that, The end of the piston rod is inserted into a flange (8) with a bushing. On the left and right parts of the flange, there are respectively a left vertical guide rod (81) and a right vertical guide rod (82). Both the left vertical guide rod and the right vertical guide rod are slidably connected to the cross beam; a left baffle is provided at the upper end of the left vertical guide rod, and a right baffle is provided at the upper end of the right vertical guide rod; the force sensor is connected to the flange through bolts.

3. The prosthetic knee joint dynamics performance testing machine according to claim 1, characterized in that, The structures of the lower fixture and the upper fixture are the same. The lower fixture includes a lower strip plate (121), a lower vertical hole provided in the left part of the lower strip plate, and a lower strip hole (122) extending along the length direction to the right of the lower vertical hole; on the front outer surface of the lower strip plate corresponding to the length direction of the lower strip hole, there is a lower scale; the lower end of the prosthetic knee joint is inserted into the lower vertical hole, and a lower bolt that can pass through the lower vertical hole and the lower end of the prosthetic knee joint is provided on the lower strip plate.

4. The prosthetic knee joint dynamic performance testing machine according to claim 1 or 2 or 3, characterized in that, The upper ends of the left and right upright columns are connected by a U-shaped horizontal connecting rod (7).

5. A test method for a prosthetic knee joint dynamics performance testing machine according to claim 1, characterized in that, It includes a static verification test: Step 5-1: Fix the prosthetic knee joint to be tested on the upper fixture and the lower fixture, and set the specified test force F on the industrial control computer. SET Loading curve, stable test force F STAB Loading curve, F SP Loading curve and F SP Unloading curve; Step 5-2, apply a test force F to the prosthetic knee joint SET , so that F SET is at 0.8F C and hold for 30 s before removing: Step 5-2-1, the industrial control computer performs co-frequency sampling on the F SET loading curve and the signal detected by the force sensor to obtain the target loading force F SET_K1 at the current moment and the actual loading force F K1 ; the initial value of K1 is 1; a PID controller and a linear iterative controller are provided in the industrial control computer, and both the PID controller and the linear iterative controller are software modules; Step 5-2-2, the industrial control computer calculates the error e K1 : e K1 = F SET_K1 - F K1 ; PID controller calculates x K1 : where e0 = 0, x K1 represents the output value of the PID controller at the K1-th sampling, and K P1 is the set proportionality coefficient of the PID controller, and K I1 is the set integral coefficient of the PID controller, and K D1 is the set derivative coefficient of the PID controller; Step 5-2-3, the linear iterative controller calculates the error compensation term Δx K1 : Δx K1 = Δx K1-1 + Γ·e K1-1 ; Among them, Γ is the learning gain matrix, and Δx1 = 0; XXmax is set in the industrial control computer for calculation When |x cmd_K1 | ≤ XXmax, the industrial control computer will output x cmd_K1 to the PID control unit; Step 5-2-4, the PID control unit samples the signal sent by the industrial control computer to the PID control unit and the signal detected by the position sensor, and obtains the target displacement z of the piston rod of the static pressure servo oil cylinder cmd_K1 and the current actual displacement z K2 ; among them, the initial value of K2 is 1, and z KK2 =x K2 ; cmd_K1 ; Step 5-2-5, the PID control unit calculates the error E K2 : E K2 = z K2 -z KK2 ; The PID control unit performs PID operation: Among them, y K2 represents the output value of the PID control unit at the K2-th sampling of the PID control unit, K P2 is the set proportionality coefficient of the PID control unit, K I2 is the set integral coefficient of the PID control unit, K D2 is the set inner-loop differential coefficient of the PID control unit; Step 5-2-6, YYmax is provided in the PID control unit. When |y K2 | ≤ YYmax, the PID control unit will send y K2 to the electro-hydraulic servo valve; Increase the value of K2 by 1, and the PID control unit samples the signals transmitted by the industrial control computer to the PID control unit and detected by the position sensor to obtain the target displacement z of the piston rod of the static pressure servo cylinder cmd_K1 and the current actual displacement z K2 ; Return to step 5-2-5; KK2 ; Return to step 5-2-5; Step 5-2-7, the electro-hydraulic servo valve controls the lifting and the lifting amplitude of the piston rod according to y K2 ; when the force detected by the force sensor < 0.8F C , increase the value of K1 by 1, and the industrial control computer continues to sample the F SET loading curve and the signal detected by the force sensor at the same frequency to obtain the target loading force F SET_K1 at the current moment and the actual loading force F K1 ; return to Step 5-2-2; When the force detected by the force sensor = 0.8F C , the industrial control computer controls the electro-hydraulic servo valve through the PID control unit, and the electro-hydraulic servo valve controls the piston rod to remain stationary at the current position for 30 s; Step 5-2-8, repeat Steps 5-2-1 to 5-2-7, using the set test force F SET Unloading curve, gradually release the force applied to the prosthetic knee joint; Using step 5-2, apply a stable test force F STAB to the loading curve and load the force detected by the force sensor to F STAB , and record the displacement L1 detected by the displacement sensor at this time; Using step 5-2, with a loading curve having a slope of 100 N / s - 250 N / s, smoothly load the force detected by the force sensor from F SP to the set test force F STAB and hold for 30 seconds; SP ​ Using step 5-2, with a slope of 100 N / s - 250 N / s for F SP unloading curve, the force detected by the force sensor is smoothly reduced from F SP to F STAB , and record the displacement L2 detected by the displacement sensor at this time; The industrial control computer calculates the deformation amount D: D = L2 - L1; If the deformation amount D ≤ 15 mm, it is determined that the prosthetic knee joint passes the static verification test, and D is output; the static verification test ends.

6. The test method of the prosthetic knee joint dynamics performance testing machine according to claim 5, characterized in that, It also includes a static destruction test: Fix the prosthetic knee joint to be measured on the upper fixture and the lower fixture; Set the specified test force F on the industrial control computer SET Loading curve and test force F SU Loading curve; Repeat step 5-2, using the test force F SET Loading curve, apply the test force F to the prosthetic knee joint SET , so that F SET is at 0.8F C Keep it for 30 s and then remove it; Using Step 5-2, apply the test force F SU to the loading curve and load the force detected by the force sensor to F SU , and hold for 30 seconds; If the prosthetic knee joint is not damaged within 30 seconds, it is determined that the prosthetic knee joint meets the requirements of the static destruction test, and the static destruction test ends.

7. The test method of the prosthetic knee joint dynamic performance testing machine according to claim 5 or 6, characterized in that, It also includes a dynamic loading test: Step 7-1, fix the prosthetic knee joint to be measured on the upper fixture and the lower fixture; Set the maximum displacement L SET 、the maximum number of force loading times i SET 、the maximum number of part replacement times n SET 、the minimum test force F MIN Loading curve, test force F C Loading curve and test force F C Unloading curve; Step 7-2: Using Step 5-2, apply the minimum test force F MIN to the loading curve and apply the minimum test force F to the prosthetic knee joint MIN ; the industrial control computer sets the count i1 value of the force loading counter to 0 and the count i2 value of the part replacement counter to 0; Step 7-3, using Step 5-2, apply the test force F C to the loading curve and apply the test force F to the prosthetic knee joint C , F C > F MIN , and record the displacement L detected by the displacement sensor at this time. The industrial control computer increments both the i1 value and the i2 value by 1; Step 7-4, if L > L SET , then the industrial control computer makes a judgment that the test sample fails the dynamic loading test; If L ≤ L SET and i2 < n SET and i1 < i SET then use Step 5-2 to release the test force F C applied to the prosthetic knee joint by the unloading curve C and return to Step 7-3; If L ≤ L SET and i2 ≥ n SET and i1 < i SET , the industrial control computer makes a judgment that the parts of the prosthetic knee joint need to be replaced, and the industrial control computer emits an alarm sound. After the staff hears the alarm sound, they replace the parts of the prosthetic knee joint. After the parts are replaced, the staff gives the industrial control computer a command to continue the test through the button, and the industrial control computer sets i2 = 0 and returns to step 7-3; If L ≤ L SET , i2 < n SET and i1 ≥ i SET , then the industrial control computer makes a judgment that the prosthetic knee joint passes the dynamic loading test.

Images