Bionic knee joint system and cartilage mechanics testing method

Abstract

The present application relates to a kind of bionic knee joint system and cartilage mechanics test method, the system includes bionic knee joint mechanism, dynamometer and lifting platform, the bionic knee joint mechanism is set on dynamometer, the dynamometer is set on lifting platform;The bionic knee joint mechanism includes quasi-joint head rocker, quasi-joint socket base, drive motor, eccentric wheel and fixed pivot, the quasi-joint head rocker is inserted quasi-joint socket base, the eccentric wheel is inserted quasi-joint head rocker, the drive motor drives eccentric wheel rotation, drives quasi-joint head rocker swing in quasi-joint socket base around fixed pivot, quasi-joint head recess is set on the quasi-joint head rocker, quasi-joint socket base is set on quasi-joint socket recess, quasi-joint head recess and quasi-joint socket recess are embedded in cartilage material.Compared with prior art, the present application can accurately reproduce the knee joint mechanics environment, and can be quantitatively analyzed in real time to cartilage material interface impedance characteristics.

Description

Technical Field

[0001] This invention belongs to the field of biomedical engineering technology and relates to a biomimetic knee joint system and a cartilage biomechanical testing method. Background Technology

[0002] Osteoarthritis (OA) and other degenerative joint diseases are among the leading causes of disability worldwide. Studies have shown that the physiological homeostasis and pathological degeneration of articular cartilage are deeply dependent on a complex biomechanical environment. The human knee joint experiences multidimensional coupled mechanical loads during daily walking, exercise, and weight-bearing activities: not only periodic vertical pressure, but also high-frequency sliding friction and shear forces, as well as dynamic frequency modulation that varies with gait. This multi-field coupled mechanical stimulation of pressure, frequency, and friction is a key signal for maintaining chondrocyte function, promoting matrix synthesis, and regulating lubrication and nutrient metabolism; its imbalance directly leads to cartilage degeneration and the development of osteoarthritis. With the rapid development of artificial joints, cartilage replacement materials, hydrogels, and biomimetic materials for joint interfaces, related research is no longer satisfied with measuring single loads or single friction indices. There is an urgent need to systematically evaluate the comprehensive mechanical response and biological behavior of material interfaces under controllable pressure, controllable movement frequency, and dynamic contact conditions. Therefore, constructing an experimental and monitoring platform in vitro that can accurately reproduce the multi-field coupling environment of knee joint pressure-frequency-friction has important scientific and clinical value for evaluating the performance of biomaterials, regenerating tissue-engineered cartilage, designing biomimetic joints, and screening drugs.

[0003] While existing cartilage biomechanical simulation devices or organoid chips can achieve basic pressure culture or simple motion stimulation, they still have significant shortcomings in realistically reproducing the complex biomechanical environment of the knee joint. The knee joint experiences not a single constant load during walking, running, and weight-bearing, but a dynamic coupling process involving periodic pressure, multi-frequency motion, and frictional shear. However, most existing devices remain at the level of constant static pressure, single friction tests, or simple reciprocating motion, failing to simultaneously simulate the correlation between pressure amplitude changes, motion frequency changes, and contact interface responses. This results in significant deviations between in vitro testing conditions and real joint conditions. Furthermore, most existing devices only focus on single output indicators such as load, displacement, or friction force, lacking the real-time quantification capability of impedance characteristics, frictional shear behavior, and comprehensive interface responses of cartilage or biomimetic materials during dynamic stimulation. Therefore, it is difficult to establish a quantitative relationship between pressure, frequency, and material response, limiting a deeper understanding of cartilage degeneration mechanisms and the essence of material properties. Furthermore, traditional equipment generally suffers from limitations in control methods, including limited adjustment range, insufficient automation, and weak closed-loop control capabilities. This makes it difficult to achieve precise programming and stable output of pressure, frequency, and motion patterns. It also has limitations in sample adaptability and test versatility, failing to meet the systematic evaluation needs of different types of cartilage samples, organoids, and biomimetic materials. Therefore, there is an urgent need to construct a biomimetic testing platform that overcomes the bottlenecks of existing technologies in terms of realism, quantification, and versatility.

[0004] Patent CN107764675A discloses a knee joint wear testing machine, comprising a linkage drive device and a simulation motion device. The linkage drive device includes a motor, a linkage mechanism, and a lower leg rod. The rotational motion generated by the motor causes the lower leg rod to reciprocate through the linkage mechanism. The simulation motion device includes a thigh rod, prosthesis specimen I, prosthesis specimen II, a connecting buckle, a top rod, and weights. Prosthesis specimen I and prosthesis specimen II are respectively placed at the top of the thigh rod and the lower leg rod. The reciprocating motion of the lower leg rod drives the thigh rod to reciprocate through the connecting buckle. The thigh rod is connected to the top rod, which has weights that can be placed to simulate the wear performance of the prosthesis material under different weight conditions. Although this patent uses a weight-based gravity loading method to simulate vertical loads under different weight conditions, the load is fixed and always a static constant value. It cannot achieve dynamic fluctuations in pressure amplitude within a set range, and cannot simulate the real dynamic load of periodic changes in gait, resulting in a large deviation between the test conditions and the actual joint working conditions.

[0005] Patent CN119178693A discloses a low-speed reciprocating curved surface friction testing machine for simulating the human knee joint. It includes a machine body with an upper clamping assembly for clamping an upper test piece and a lower clamping assembly for clamping a lower test piece movably mounted on the body. The machine body also includes a lifting drive mechanism that drives the lower clamping assembly upwards. This mechanism causes the lower test piece to rise, so that its top is pressed against the bottom of the upper test piece with a preset pre-pressure, simulating the load state of the human knee joint. The machine body also includes a swing drive device that drives the upper clamping assembly to swing back and forth, causing friction between the upper and lower test pieces, simulating the frictional motion of the human knee joint. Although this patent installs a friction sensor within an arc-shaped groove, it lacks a quantitative calculation model, making it impossible to achieve online quantification of the comprehensive mechanical response of the material interface under pressure-frequency-friction multi-field coupling. It can only obtain a single friction force value and lacks a systematic quantitative study of the cartilage material properties.

[0006] Patent CN108469392A discloses a temperature-controllable knee joint friction and wear testing machine, including a base and an experimental chamber mounted on the base. The experimental chamber is divided into an upper cavity, a middle cavity, and a lower cavity from top to bottom. A servo motor and an eccentric wheel are installed in the upper cavity. A transmission rod is mounted on the eccentric wheel, which drives the upper sample clamp in the middle cavity to move repeatedly along a guide rail. The upper beam is a fixed beam and cannot move. An environmental chamber is also provided in the middle cavity, around which an infrared thermal imager for detection and a temperature control system for controlling the ambient temperature are installed. The lower beam is a movable beam that can move up and down. A moving beam loading device is installed in the lower cavity, which flexibly loads the moving beam under the action of a spring. Although this patent uses an upper servo motor, an eccentric wheel, and a transmission rod to drive the upper sample clamp to reciprocate along a linear guide rail, this motion is a linear translational reciprocating motion, not the actual friction mode of a knee joint. It cannot accurately reproduce the motion relationship of the curved surface contact of the joint, and its biomimicry level is insufficient. Summary of the Invention

[0007] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a biomimetic knee joint system and a cartilage biomechanical testing method. This invention can accurately reproduce the mechanical environment of the knee joint and can perform real-time quantitative analysis of the interfacial impedance characteristics of cartilage materials.

[0008] The objective of this invention can be achieved through the following technical solutions: One of the technical solutions of the present invention is to provide a bionic knee joint system, which includes a bionic knee joint mechanism, a force gauge and a lifting platform, wherein the bionic knee joint mechanism is disposed on the force gauge and the force gauge is disposed on the lifting platform; The bionic knee joint mechanism includes a simulated joint head rocker arm, a simulated joint socket base, a drive motor, an eccentric wheel, and a fixed rotating shaft. The simulated joint head rocker arm is inserted into the simulated joint socket base, and the eccentric wheel is inserted into the simulated joint head rocker arm. The drive motor drives the eccentric wheel to rotate, causing the simulated joint head rocker arm to swing around the fixed rotating shaft within the simulated joint socket base. The simulated joint head rocker arm has a simulated joint head groove, and the simulated joint socket base has a simulated joint socket groove. Cartilage material is embedded in the simulated joint head groove and the simulated joint socket groove.

[0009] Furthermore, the simulated joint head rocker arm includes a disc portion and a straight rod portion connected to each other. The disc portion has a simulated joint head groove at one end away from the straight rod portion. The fixed rotating shaft passes through the center of the disc portion, and the disc portion rotates around the fixed rotating shaft. The straight rod portion has a motion guide rail inside.

[0010] Furthermore, a motion guide groove is provided on the pseudo-articular socket base, the disc part is inserted into the motion guide groove and rotates in the motion guide groove, and a pseudo-articular socket groove is provided at the bottom of the motion guide groove, and the pseudo-articular head groove is directly opposite to the pseudo-articular socket groove when the pseudo-articular head rocker arm is kept vertical.

[0011] Furthermore, the output end of the drive motor is connected to the drive motor shaft; An eccentric shaft is provided on the eccentric wheel. The eccentric shaft is inserted into the motion guide rail and slides within the motion guide rail. The drive motor shaft is inserted into the eccentric wheel. The rotation of the drive motor shaft drives the eccentric wheel to rotate, causing the straight rod to swing.

[0012] Furthermore, the force gauge has a base socket, and the pseudo-articular socket base is inserted into the base socket.

[0013] Furthermore, the lifting platform includes a control motor, a lead screw, an upper platform, a base, an upper guide rod, a lower guide rod, and a cross linkage. The upper platform and the base cooperate with the upper guide rod and the lower guide rod, respectively, and are connected to each other through the cross linkage. The control motor drives the upper guide rod to slide down the upper platform through the lead screw, and the lower guide rod slides on the base. The cross linkage drives the upper platform to rise and fall.

[0014] Furthermore, the output end of the control motor is connected to the control motor shaft, and a motor shaft gear is provided at the end of the control motor shaft; The lead screw includes a lead screw shaft and a lead screw shaft gear. The upper guide rod has a threaded hole. The lead screw shaft passes through the threaded hole and is threadedly engaged with the upper guide rod. The end of the lead screw shaft is provided with a lead screw shaft gear. The motor shaft gear meshes with the lead screw shaft gear. The rotation of the motor shaft gear drives the lead screw shaft gear to rotate, which in turn drives the lead screw shaft to rotate and causes the upper guide rod to move horizontally.

[0015] One of the technical solutions of the present invention is to provide a cartilage biomechanical testing method, which uses the aforementioned system to perform biomechanical testing on cartilage materials, and the method includes the following steps: According to the law of conservation of energy, the electrical work consumed by the relative motion between cartilage materials during the system's operation... W e1 Equal to frictional work W e2 Then the impedance factor of cartilage material μ for, In the formula U 1 represents the output voltage of the drive motor under load. I 1 represents the output current of the drive motor under load. U 0 represents the output voltage of the drive motor under no-load conditions. I 0 represents the output current of the drive motor under no-load conditions. F n The normal force acting on the cartilage material. v The rotational speed of the eccentric wheel, θ The angle between the center of the simulated articular head groove and the trajectory of its motion. R The radius of motion of the simulated articulated rocker arm.

[0016] Furthermore, when no cartilage material is placed in the articular head groove and articular socket groove, the system operates under no-load conditions. t The electrical work done in a given time is W 0; When cartilage material is placed in the articular head groove and articular fossa groove, the system operates under load. t The electrical work done in a given time is W 1; then during the system operation, the relative motion between cartilage materials is in t Electrical work consumed in a given time W e1 equal W 1- W 0, which is equal to U 1 I 1 t - U 0 I 0 t .

[0017] Furthermore, during system operation, the distance of relative motion between the pseudo-articular head rocker arm and the pseudo-articular socket base corresponding to one rotation of the eccentric wheel is... l Equal to 2 θR ; When the rotational speed of the eccentric wheel, that is, the number of revolutions per second, is v At that time, t Number of revolutions of the eccentric wheel within a time periods equal vt Then in t The total distance of relative motion between the articular head rocker arm and the articular socket base within a given time period L equal sl The frequency of relative motion between the articular head rocker arm and the articular socket base. f Numerically related to the rotational speed of the eccentric wheel v equal; The compressive force between the cartilage material placed in the articular head groove and the articular fossa groove is approximately equal to the normal force acting on the cartilage material. F n The tangential force on the cartilage material F t Equal to the impedance factor of cartilage material μ and normal force F n The product of the two; then the relative motion between the cartilage materials during the system's operation. t Frictional work consumed in time W e2 equal F t L That is equal to μF n · vt ·2 θR .

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The system in this invention adopts an eccentric wheel-rocker arm-joint socket bionic mechanism design, which accurately reproduces the swing-sliding friction motion mode of the knee joint, and realizes the natural coupling of pressure loading and friction shear motion; (2) The pressure closed-loop control system composed of the lifting platform and the force gauge, and the frequency closed-loop control system composed of the drive motor speed feedback in this invention, based on the PID algorithm, realizes independent and precise control of pressure amplitude (constant or dynamic fluctuation) and motion frequency, ensuring that the parameters remain stable at the set value during the deformation, wear and other state changes of cartilage material. (3) In this invention, the system collects the output voltage and output current of the drive motor in real time, and combines the pressure, frequency and kinematic parameters of the mechanism to establish a quantitative calculation model of the interface impedance factor of cartilage material based on the principle of energy conservation, thereby realizing the online quantitative characterization of the comprehensive mechanical response of cartilage material under multi-field coupling of pressure-frequency-friction. (4) The system in this invention is equipped with wireless communication and visualization interface, supports remote parameter setting, real-time monitoring of operating status and multi-dimensional data synchronous recording, and can be applied to mechanical testing and evaluation of various types of cartilage materials; (5) The system in this invention can not only simulate physiological gait and pathological load, providing a real mechanical environment for the study of cartilage degeneration mechanism, but also provide a new quantitative evaluation index and engineering design basis for biomimetic joint material screening, lubrication performance evaluation and functional optimization through impedance factor quantification. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the bionic knee joint system in an embodiment of the present invention; Figure 2 This is an exploded structural diagram of the bionic knee joint system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the bionic knee joint mechanism in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the simulated articulated head rocker arm in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the pseudo-articular socket base in an embodiment of the present invention; Figure 6 This is a schematic diagram of the drive motor in an embodiment of the present invention; Figure 7 This is a schematic diagram of the eccentric wheel in an embodiment of the present invention; Figure 8 This is a schematic diagram of the force gauge in an embodiment of the present invention; Figure 9 This is a schematic diagram of the lifting platform in an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of the components on the upper platform in an embodiment of the present invention; Figure 11 This is a schematic diagram illustrating the logical relationship of the control components in an embodiment of the present invention; Figure 12 This is a schematic diagram of the interactive interface of the control component in an embodiment of the present invention; Figure 13 This is a schematic diagram illustrating the parameter calculation of the motor control strategy in an embodiment of the present invention; Figure 14 This is a schematic diagram of the operating state of the bionic knee joint mechanism in an embodiment of the present invention.

[0020] Explanation of markings in the diagram: 1- Bionic knee joint mechanism, 2- Force gauge, 3- Lifting platform; 101-Articular head rocker arm, 102-Articular socket base, 103-Drive motor, 104-Eccentric wheel, 105-Fixed rotating shaft; 1011-Mock joint head groove, 1012-Motion guide rail, 1015-Rotating shaft through hole, 1021-Mock joint socket groove, 1031-Drive motor shaft, 1041-Shaft hole, 1042-Eccentric shaft; 201 - Force gauge display screen; 202 - Base mounting slot; 2031 - Through hole for force gauge bolts; 301-Control motor, 302-Lead screw, 303-Upper platform, 304-Base, 305-Upper guide rod, 306-Lower guide rod, 307-Cross linkage, 308-Rotating bearing; 3011 - Motor shaft gear, 3021 - Screw shaft gear, 3031 - Lifting platform bolt through hole. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and do not imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example 1: A bionic knee joint system, such as Figure 1 and Figure 2 As shown, it includes a bionic knee joint mechanism 1, a force gauge 2, and a lifting platform 3. The bionic knee joint mechanism 1 is mounted on the force gauge 2, and the force gauge 2 is mounted on the lifting platform 3. like Figure 3As shown, the bionic knee joint mechanism 1 includes a simulated joint head rocker arm 101, a simulated joint socket base 102, a drive motor 103, an eccentric wheel 104, and a fixed rotating shaft 105. The simulated joint head rocker arm 101 is inserted into the simulated joint socket base 102, and the eccentric wheel 104 is inserted into the simulated joint head rocker arm 101. The drive motor 103 drives the eccentric wheel 104 to rotate, causing the simulated joint head rocker arm 101 to swing around the fixed rotating shaft 105 within the simulated joint socket base 102. A simulated joint head groove 1011 is provided on the simulated joint head rocker arm 101, and a simulated joint socket groove 1021 is provided on the simulated joint socket base 102. Cartilage material is embedded in the simulated joint head groove 1011 and the simulated joint socket groove 1021. In this embodiment, the cartilage material is selected from natural cartilage or cartilage biomimetic materials. Currently, the commonly used animal sources of natural cartilage for scientific research are mainly selected from pigs, cattle, sheep or rabbits. The mainstream cartilage biomimetic materials in clinical practice are mainly selected from cobalt-chromium-molybdenum alloy, titanium alloy, ultra-high molecular weight polyethylene or bioceramics. The cartilage biomimetic materials explored at the forefront are mainly selected from porous tantalum metal or hydrogel-based cartilage substitutes. like Figure 4 As shown, the simulated joint head rocker arm 101 includes a disc part and a straight rod part connected to each other. A simulated joint head groove 1011 is provided at one end of the disc part away from the straight rod part. A fixed rotating shaft 105 passes through the center of the disc part and rotates around the fixed rotating shaft 105. A motion guide rail 1012 is provided inside the straight rod part. In this embodiment, a rotating shaft through hole 1015 is provided in the center of the disc portion, and a fixed rotating shaft 105 passes through the rotating shaft through hole 1015 and is fixed to the outside, such as a vertical mounting plate. like Figure 5 As shown, a motion guide groove is provided on the pseudo-articular socket base 102, and the disc part is inserted into the motion guide groove and rotates in the motion guide groove. A pseudo-articular socket groove 1021 is provided at the bottom of the motion guide groove, and the pseudo-articular head groove 1011 is directly opposite to the pseudo-articular socket groove 1021 when the pseudo-articular head rocker arm 101 is kept vertical. In this embodiment, the pseudo-articular socket base 102 has rotating shaft through slots on both sides of the motion guide groove, and the fixed rotating shaft 105 passes through the rotating shaft through slots. like Figure 6 As shown, the output end of the drive motor 103 is connected to the drive motor shaft 1031; In this embodiment, the fixed end of the drive motor 103 is fixed to the outside, such as on a vertical mounting plate; like Figure 7 As shown, an eccentric shaft 1042 is provided on the eccentric wheel 104. The eccentric shaft 1042 is inserted into the motion guide rail 1012 and slides within the motion guide rail 1012. The drive motor shaft 1031 is inserted into the eccentric wheel 104. The drive motor shaft 1031 rotates, causing the eccentric wheel 104 to rotate, which in turn causes the straight rod to swing. In this embodiment, the eccentric wheel 104 has a shaft hole 1041 in the center, and the drive motor shaft 1031 is in a flat fit with the shaft hole 1041. like Figure 8 As shown, the force gauge 2 has a base slot 202, and the pseudo-articular base 102 is inserted into the base slot 202; In this embodiment, the force gauge 2 is equipped with a force gauge display screen 201, which displays the measured pressure value. In this embodiment, the force gauge 2 is provided with a bracket, and the bracket is provided with a force gauge bolt through hole 2031, through which the bolt passes. like Figure 9 As shown, the lifting platform 3 includes a control motor 301, a lead screw 302, an upper platform 303, a base 304, an upper guide rod 305, a lower guide rod 306, and a cross-link 307. The upper platform 303 and the base 304 cooperate with the upper guide rod 305 and the lower guide rod 306 respectively, and are connected to each other through the cross-link 307. The control motor 301 drives the upper guide rod 305 to slide under the upper platform 303 through the lead screw 302, and the lower guide rod 306 slides on the base 304. The upper platform 303 is raised and lowered through the cross-link 307. like Figure 10 As shown, in this embodiment, a lifting platform bolt through hole 3031 is provided on the upper platform 303, and the bolt passes through the lifting platform bolt through hole 3031. The force gauge 2 is fixed to the upper platform 303 by the bolt. The output end of the control motor 301 is connected to the control motor shaft, and the end of the control motor shaft is provided with a motor shaft gear 3011; In this embodiment, the fixed end of the control motor 301 is fixed to the upper platform 303; The lead screw 302 includes a lead screw shaft and a lead screw shaft gear 3021. The upper guide rod 305 has a threaded hole, through which the lead screw shaft passes and is threadedly engaged with the upper guide rod 305. The end of the lead screw shaft is provided with a lead screw shaft gear 3021. The motor shaft gear 3011 meshes with the lead screw shaft gear 3021. The rotation of the motor shaft gear 3011 drives the lead screw shaft gear 3021 to rotate, which in turn drives the lead screw shaft to rotate and causes the upper guide rod 305 to move horizontally. In this embodiment, an upper frame is provided under the upper platform 303, the upper guide rod 305 slides in the upper frame, the lead screw shaft is inserted into the upper frame, a rotating bearing is provided at the pivot point of the lead screw shaft and the upper frame, and the lead screw shaft gear 3021 is provided outside the upper frame. In this embodiment, a lower frame is provided on the base 304, and the lower guide rod 306 slides within the lower frame; In this embodiment, an upper support block is provided under the upper platform 303, and an upper fixing rod is provided under the upper support block; In this embodiment, a lower support block is provided on the base 304, and a lower fixing rod is provided on the lower support block; In this embodiment, the cross link 307 is provided with a connecting rod at the intersection; In this embodiment, the cross link 307 is provided with a rotating bearing 308 at the pivot point with the guide rod, the fixed rod and the connecting rod.

[0025] Example 2: A bionic knee joint system, such as Figure 11 As shown, the system is basically the same as in Embodiment 1, except that it also includes a control component. The control component includes a microcontroller, specifically an STM32WL microcontroller, which is electrically connected to the control motor 301 and the drive motor 103. As the core control unit, the microcontroller controls the position of the upper platform 303 by driving the control motor 301, thereby controlling the compressive force between the cartilage material placed in the pseudo-articular head groove 1011 and the pseudo-articular socket groove 1021. Closed-loop control of pressure is achieved through pressure negative feedback. At the same time, the frequency of relative motion between the pseudo-articular head rocker arm 101 and the pseudo-articular socket base 102 is controlled by controlling the rotation speed of the drive motor 103, and closed-loop control of frequency is achieved through frequency negative feedback. The control components also include a wireless communication module and a computer. The wireless communication module is integrated into the STM32WL microcontroller system-on-a-chip. The microcontroller is electrically connected to the wireless communication module, and the microcontroller and the computer transmit signals through the wireless communication module. When the system is placed in the incubator, it can be controlled wirelessly without disrupting the culture environment due to the frequent opening and closing of the incubator.

[0026] like Figure 12 As shown, the computer screen displays an interactive interface, which is mainly used to visualize and set system parameters and monitor the operating status in real time, as detailed below: Before running the system, the parameters are set. The minimum pressure value is entered in the left pressure box and the maximum pressure value is entered in the right pressure box. To maintain a fixed pressure value, enter the same value in both pressure boxes. The pressure value setting represents the compressive force between the cartilage material placed in the pseudo-articular head groove 1011 and the pseudo-articular socket groove 1021. The frequency value is entered in the frequency box, representing the frequency of relative movement between the pseudo-articular head rocker arm 101 and the pseudo-articular socket base 102. The time value is entered in the time box, representing the system's running time. After setting the parameters, click the Start button to begin system operation. If an emergency occurs during operation and the system needs to be stopped, click the End button to stop the system. Box A displays the actual pressure. FThe data waveform, box b shows the actual frequency. f The data waveform, box c shows the output voltage of drive motor 103. U The data waveform, shown in box d, represents the output current of drive motor 103. I The data waveform, box e shows the impedance factor of the cartilage material. μ The data waveform will eventually be displayed in the impedance factor box, showing its average value.

[0027] like Figure 13 As shown, the control strategies for both the control motor 301 and the drive motor 103 use the PID algorithm. The PID algorithm is a linear control strategy based on deviation. The specific principle is shown in the following equation (1). (1) in r ( t ) represents the system input or desired setting value, corresponding to the pressure value and frequency value set in the interactive interface; y ( t () indicates system output, corresponding to the output during system operation. t The actual pressure and frequency values ​​over time; e ( t ) indicates input r ( t ) and output y ( t The control deviation signal generated corresponds to... t The actual time value minus the set value; u ( t This represents the control quantity acting on the controlled object, specifically the control motor 301 or the drive motor 103. t Time-driven controlled object output y ( t Follow the input r ( t The changes in ) form a closed-loop negative feedback control. The PID algorithm is the most mature and widely used regulation strategy structure in the field of control. k p This is the proportionality coefficient. k i The integral coefficient is... k d These are the differential coefficients; the values ​​of the three coefficients were all obtained during the system development process based on the effect debugging. The proportional element (P) converts the deviation signal into a proportional signal. e ( t The bias signal is amplified proportionally to generate a correction value proportional to the deviation amplitude, which determines the system's response speed and controls the steady-state error; the integrator (I) is the component that amplifies the bias signal. e (t Historical deviations are accumulated to eliminate steady-state errors and improve control accuracy; the differential element (D) reflects the deviation signal. e ( t The changing trend of the deviation has a proactive adjustment characteristic, which can apply correction before the deviation increases significantly, thereby improving the dynamic response performance of the system and increasing its stability. In the actual implementation of the PID algorithm, data is collected once every unit of time. The specific principle is shown in the following formula (2). (2) In the formula u ( k ) indicates the first k The amount of control at any given moment; e ( k ) indicates the first k The deviation signal at time, e ( k -1) indicates the first k The deviation signal from the previous unit of time.

[0028] Example 3: A method for testing the mechanical properties of cartilage, using the system described in Example 1 to perform mechanical testing on cartilage materials, comprises the following steps: When no cartilage material is placed in the articular head groove 1011 and the articular fossa groove 1021, the system operates under no-load conditions. t The electrical work done in a given time is W 0; When cartilage material is placed in the pseudo-articular head groove 1011 and pseudo-articular fossa groove 1021, the system operates under load. t The electrical work done in a given time is W 1; then during the system operation, the relative motion between cartilage materials is in t Electrical work consumed in a given time W e1 equal W 1- W 0, which is equal to U 1 I 1 t - U 0 I 0 t In the formula U 1 represents the output voltage of the drive motor 103 under load. I 1 represents the output current of the drive motor 103 under load. U 0 represents the output voltage of the drive motor 103 under no-load conditions. I 0 represents the output current of the drive motor 103 under no-load conditions; like Figure 14 As shown in the figure, during system operation, the motion trajectory of the center of the eccentric shaft 1042 is shown in Figure A, and the motion trajectory of the center of the pseudo-joint head groove 1011 is shown in Figure B. θ The angle between the center motion trajectory of the simulated articular head groove 1011, R Let the radius of motion of the pseudo-articular head rocker arm 101 be the distance of relative motion between the pseudo-articular head rocker arm 101 and the pseudo-articular socket base 102 corresponding to one rotation of the eccentric wheel 104. l Equal to 2 θR ; When the rotational speed of the eccentric wheel 104, that is, the number of revolutions per second, is v At that time, t Number of revolutions of eccentric wheel 104 within a time period s equal vt Then in t The total distance of relative motion between the articular head rocker arm 101 and the articular socket base 102 within a given time period L equal sl The frequency of relative motion between the pseudo-articular head rocker arm 101 and the pseudo-articular socket base 102 f Numerically, it corresponds to the rotational speed of the eccentric wheel 104. v equal; The compressive force between the cartilage material placed in the articular head groove 1011 and the articular fossa groove 1021 can be regarded as the normal force on the cartilage material. F n The tangential force on the cartilage material F t Equal to the impedance factor of cartilage material μ and normal force F n The product of the two; then the relative motion between the cartilage materials during the system's operation. t Frictional work consumed in time W e2 equal F t L That is equal to μF n · vt ·2 θR ; According to the law of conservation of energy, the relative motion between cartilage materials during system operation... t Electrical work consumed in a given time W e1 Equal to frictional work W e2 The impedance factor of the cartilage material can then be calculated. μ See equation (3) below.

[0029] (3) Example 4: A cartilage biomechanical testing method is basically the same as that in Example 3, except that the system described in Example 2 is used to perform the biomechanical testing of cartilage materials under constant pressure mode. The specific differences are as follows: The cartilage material is placed in the simulated articular head groove 1011 and the simulated articular socket groove 1021. The required pressure, frequency, and time parameters are set. The start button is clicked to control the motor 301 to run. The lifting and lowering of the upper platform 303 is dynamically adjusted according to the error between the pressure value measured by the force gauge 2 and the set pressure value, so that the actual pressure is always consistent with the set pressure. At the same time, the drive motor 103 is run, and the frequency value is continuously adjusted according to the error between the actual frequency value and the set frequency value, so that the actual frequency is always consistent with the set frequency.

[0030] When the set pressure, frequency, and time parameters are different, boxes c and d display the recorded output voltage. U and output current I They will also differ. By analyzing various parameters and data, the experimental phenomena and results of different control groups can be quantitatively analyzed.

[0031] Example 5: A cartilage biomechanical testing method is basically the same as that in Example 3, except that the system described in Example 2 is used to perform biomechanical testing of cartilage materials under dynamic pressure change mode. The specific differences are as follows: The cartilage material is placed in the simulated articular head groove 1011 and the simulated articular socket groove 1021. The required pressure, frequency, and time parameters are set, with the pressure values ​​set as the minimum and maximum pressure values, respectively. The start button is clicked to control the motor 301 to run. The upper platform 303 is dynamically adjusted according to the pressure value measured by the force gauge 2 and the set pressure value range, so that the actual pressure always fluctuates between the set minimum and maximum pressure values ​​at a certain frequency. At the same time, the drive motor 103 runs and is continuously adjusted according to the error between the actual frequency value and the set frequency value, so that the actual frequency always remains consistent with the set frequency.

[0032] When the frequency and time parameters are set the same, but the minimum and maximum pressure values ​​are different, boxes c and d display the recorded output voltage. U and output current I They will also differ. By analyzing various parameters and data, the experimental phenomena and results of different control groups can be quantitatively analyzed.

[0033] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A bionic knee joint system, characterized in that, The system includes a bionic knee joint mechanism (1), a force gauge (2), and a lifting platform (3). The bionic knee joint mechanism (1) is mounted on the force gauge (2), and the force gauge (2) is mounted on the lifting platform (3). The bionic knee joint mechanism (1) includes a simulated joint head rocker arm (101), a simulated joint socket base (102), a drive motor (103), an eccentric wheel (104), and a fixed rotating shaft (105). The simulated joint head rocker arm (101) is inserted into the simulated joint socket base (102), and the eccentric wheel (104) is inserted into the simulated joint head rocker arm (101). The drive motor (103) drives the eccentric wheel (104) to rotate, causing the simulated joint head rocker arm (101) to swing around the fixed rotating shaft (105) within the simulated joint socket base (102). A simulated joint head groove (1011) is provided on the simulated joint head rocker arm (1011), and a simulated joint socket groove (1021) is provided on the simulated joint socket base (1021). Cartilage material is embedded in the simulated joint head groove (1011) and the simulated joint socket groove (1021). The pseudo-articular head rocker arm (101) includes a disc part and a straight rod part connected to each other. A pseudo-articular head groove (1011) is provided at one end of the disc part away from the straight rod part. The fixed rotating shaft (105) passes through the center of the disc part and the disc part rotates around the fixed rotating shaft (105). A motion guide rail (1012) is provided in the straight rod part. The pseudo-articular socket base (102) is provided with a motion guide groove, the disc part is inserted into the motion guide groove and rotates in the motion guide groove, the bottom of the motion guide groove is provided with a pseudo-articular socket groove (1021), and the pseudo-articular head groove (1011) is directly opposite to the pseudo-articular socket groove (1021) when the pseudo-articular head rocker arm (101) is kept vertical; The output end of the drive motor (103) is connected to the drive motor shaft (1031); An eccentric shaft (1042) is provided on the eccentric wheel (104). The eccentric shaft (1042) is inserted into the motion guide rail (1012) and slides within the motion guide rail (1012). The drive motor shaft (1031) is inserted into the eccentric wheel (104). The rotation of the drive motor shaft (1031) drives the eccentric wheel (104) to rotate, which in turn drives the straight rod to swing.

2. The bionic knee joint system according to claim 1, characterized in that, The force gauge (2) has a base slot (202) and the pseudo-articular base (102) is inserted into the base slot (202).

3. The bionic knee joint system according to claim 1, characterized in that, The lifting platform (3) includes a control motor (301), a lead screw (302), an upper platform (303), a base (304), an upper guide rod (305), a lower guide rod (306), and a cross link (307). The upper platform (303) and the base (304) cooperate with the upper guide rod (305) and the lower guide rod (306) respectively, and are connected to each other through the cross link (307). The control motor (301) drives the upper guide rod (305) to slide under the upper platform (303) through the lead screw (302), and the lower guide rod (306) slides on the base (304). The upper platform (303) is raised and lowered through the cross link (307).

4. The bionic knee joint system according to claim 3, characterized in that, The output end of the control motor (301) is connected to the control motor shaft, and the end of the control motor shaft is provided with a motor shaft gear (3011). The lead screw (302) includes a lead screw shaft and a lead screw shaft gear (3021). The upper guide rod (305) has a threaded hole. The lead screw shaft passes through the threaded hole and is threadedly engaged with the upper guide rod (305). The end of the lead screw shaft is provided with a lead screw shaft gear (3021). The motor shaft gear (3011) meshes with the lead screw shaft gear (3021). The rotation of the motor shaft gear (3011) drives the lead screw shaft gear (3021) to rotate, which in turn drives the lead screw shaft to rotate and causes the upper guide rod (305) to move horizontally.

5. A method for testing cartilage mechanics, characterized in that, This method uses the system described in any one of claims 1 to 4 to perform mechanical testing on cartilage materials, the method comprising the following steps: According to the law of conservation of energy, the electrical work consumed by the relative motion between cartilage materials during the system's operation... W e1 Equal to frictional work W e2 Then the impedance factor of cartilage material μ for, In the formula U 1 represents the output voltage of the drive motor (103) under load. I 1 represents the output current of the drive motor (103) under load. U 0 represents the output voltage of the drive motor (103) under no-load conditions. I 0 represents the output current of the drive motor (103) under no-load conditions. F n The normal force acting on the cartilage material. v The rotational speed of the eccentric wheel (104) θ The angle between the center motion trajectory of the simulated articular head groove (1011) and the center motion trajectory. R The radius of motion of the simulated articulated rocker arm (101).

6. The cartilage biomechanics testing method according to claim 5, characterized in that, When no cartilage material is placed in the articular head groove (1011) and articular fossa groove (1021), the system operates under no-load conditions. t The electrical work done in a given time is W 0; When cartilage material is placed in the pseudo-articular head groove (1011) and pseudo-articular fossa groove (1021), the system operates under load. t The electrical work done in a given time is W 1; then during the system operation, the relative motion between cartilage materials is in t Electrical work consumed in a given time W e1 equal W 1- W 0, which is equal to U 1 I 1 t - U 0 I 0 t .

7. The cartilage biomechanics testing method according to claim 5, characterized in that, During system operation, the distance of relative motion between the pseudo-articular head rocker arm (101) and the pseudo-articular socket base (102) corresponding to one rotation of the eccentric wheel (104) is... l Equal to 2 θR ; When the rotational speed of the eccentric wheel (104), that is, the number of revolutions per second, is v At that time, t Number of revolutions of the eccentric wheel (104) within a time period s equal vt Then in t The total distance of relative motion between the pseudo-articular head rocker arm (101) and the pseudo-articular socket base (102) within a given time period. L equal sl The frequency of relative motion between the pseudo-articular head rocker arm (101) and the pseudo-articular socket base (102) f Numerically related to the rotational speed of the eccentric wheel (104) v equal; The compressive force between the cartilage material placed in the pseudo-articular head groove (1011) and the pseudo-articular fossa groove (1021) is approximately equal to the normal force acting on the cartilage material. F n The tangential force on the cartilage material F t Equal to the impedance factor of cartilage material μ and normal force F n The product of the two components; then the relative motion between the cartilage materials during the system's operation is... t Frictional work consumed in time W e2 equal F t L That is equal to μF n · vt ·2 θR .

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