Joint stiffness testing device and method based on optical platform

Abstract

The invention discloses a joint rigidity testing device and method based on an optical platform, and belongs to the technical field of robots. The joint stiffness testing device based on the optical platform comprises an optical platform system which is supported on a horizontal plane; the knee joint model is supported on the optical platform system and is positioned at one end of the optical platform system; the force / torque output system is arranged at the upper part of the knee joint model; and the mechanical arm operating system is arranged on the horizontal plane, is positioned at one end of the optical platform system and is close to the knee joint model. The device can accurately measure the rigidity of the joint of the bionic tension-compression robot during movement, provides a high-precision test result, and is convenient to use. According to the joint rigidity testing method based on the optical platform, the rigidity of the bionic tension-compression robot joint can be accurately measured in real time through a data processing algorithm, the testing process is stable and reliable, and the testing result is high in precision.

Description

Technical Field

[0001] The invention relates to a joint stiffness testing device and method based on an optical platform, belonging to the technical field of robots. Background Art

[0002] In recent years, the rapid development of robotics technology has led to the widespread application of robots in industrial production, medical care, service industries and other fields. The joints of robots are the core components of robot movement and task execution. The stiffness of the joints has an important impact on the robot's movement accuracy, stability and execution ability. In the field of mechanical design and robotics, joint stiffness is an important parameter to measure the rigidity of robot joint movement. Therefore, accurately measuring and evaluating the stiffness of robot joints is a key issue in improving robot performance and optimizing robot motion control.

[0003] At present, there are two main methods for testing the stiffness of robot joints: one is based on mathematical modeling, and the other is based on experimental testing. The mathematical modeling method requires a detailed analysis of the structure and materials of the robot and complex mathematical calculations to obtain a theoretical model of joint stiffness. However, due to the complexity and diversity of the structure and materials of the robot, the mathematical modeling method is often difficult to accurately describe the true stiffness of the robot joint. In addition, the mathematical modeling method has a large amount of calculations and high computational complexity, which is not suitable for real-time testing and rapid application.

[0004] The method based on experimental testing is currently the most commonly used method for testing the stiffness of robot joints. This method uses external torque to act on the robot joints, and then measures the displacement of the joints to calculate the stiffness of the joints. However, there are some problems with existing testing devices and methods. For example, most of the existing testing devices are complex, bulky, and inconvenient to operate, and cannot meet the requirements for accurate measurement of robot joint stiffness. In addition, the existing testing methods have certain errors and uncertainties in the implementation process, which limits the accuracy and reliability of the test results.

[0005] In view of the above problems, the present invention proposes a joint stiffness testing device and method based on an optical platform to solve the defects of the prior art. The device and method are simple, reliable, and can accurately measure the stiffness of robot joints.

[0006] In summary, there are some problems with the existing robot joint stiffness testing device and method, such as complex testing device, inconvenient operation, large error in the testing method, etc. Therefore, it is necessary to provide a new joint stiffness testing device and method to solve the defects of the prior art. The present invention aims to provide a simple, reliable and accurate device and method for measuring the joint stiffness of a robot to meet the needs of the development of robot technology. Summary of the invention

[0007] The present invention designs and develops a joint stiffness testing device based on an optical platform, which can accurately measure the stiffness of the joints of a bionic tension-compression robot during movement, provides high-precision test results, and is easy to use.

[0008] The present invention also designs and develops a joint stiffness testing method based on an optical platform. Through a data processing algorithm, the stiffness of the joints of a bionic tension-compression robot can be measured in real time and accurately. The testing process is stable and reliable, and the test results are highly accurate.

[0009] The technical solution provided by the present invention is: A joint stiffness testing device and method based on an optical platform, comprising: An optical table system, the support of which is arranged on a horizontal plane, and comprises: A knee joint model, which is supported on the optical platform system and located at one end of the optical platform system; A force or torque output system, which is arranged on the upper part of the knee joint model; A robot arm operating system is arranged on a horizontal plane and is located at one end of the optical platform system, close to the knee joint model; The optical platform comprises: An optical platform, the support of which is arranged on a horizontal plane; The following are arranged in sequence along the longitudinal midline of the optical platform: two hamstring simulation loaders, connecting mechanisms, and a quadriceps simulation loader; The knee joint model is fixedly arranged on the connecting mechanism.

[0010] Preferably, the hamstring simulation loader, the connecting mechanism and the quadriceps simulation loader are all provided with pulleys, and the pulleys are located in the same straight line.

[0011] Preferably, the knee joint model is provided with: a femur model, a patella model, a tibia model and a connecting device in sequence from one end to the other end.

[0012] Preferably, the femoral model is fixedly arranged on the connecting mechanism.

[0013] Preferably, the robotic arm operating system comprises: A support base, which is arranged on a horizontal plane; A mechanical arm base, which is fixedly arranged at one end of the support base; A mechanical arm power supply box, which is fixedly arranged at the other end of the support base; The first shoulder joint, the second shoulder joint, the elbow joint, the first wrist joint, the second wrist joint and the third wrist joint are connected in sequence.

[0014] Preferably, the hamstring simulation loader has the same structure as the quadriceps simulation loader, and both include: A loader base, which is fixedly connected to the optical platform; The loader pulley is rotatably supported on the loader base.

[0015] Preferably, the connecting mechanism comprises: A connecting base, which is fixedly arranged on the optical platform; A sleeve, which is fixedly arranged at one end of the connecting base, and the femur model is fixedly arranged in the sleeve; Two supporting plates, which are relatively fixedly arranged on the connecting base and located on one side of the sleeve; A connecting roller is rotatably supported and arranged between the two supporting sheets.

[0016] A joint stiffness testing method based on an optical platform, using the joint stiffness testing device based on an optical platform, comprising: Initial setup: Mount the knee joint model on the optical platform system and make preliminary adjustments through the robotic arm operating system to ensure that the test device is in a stable state; Sensor calibration: Zero point calibration and calibration of the six-dimensional force sensor to ensure the accuracy of the measurement data; Data collection and processing: During the predetermined movement of the knee joint model, the force / torque data is collected through the sensor, filtered, and converted into values ​​in the local coordinate system; Real-time state evaluation and stiffness calculation: Use Kalman filter and real-time monitoring algorithm to evaluate the real-time state of the joint and calculate the stiffness of the joint under different motion states; Error analysis and result verification: Perform error analysis on the calculated stiffness value to verify the reliability of the test results, and ensure the consistency of the results through multiple tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the joint stiffness testing device based on the optical platform described in the present invention.

[0018] Figure 2 It is a schematic structural diagram of the optical platform system described in the present invention.

[0019] Figure 3 It is a schematic diagram of the structure of the connection device between the platform and the femur model described in the present invention.

[0020] Figure 4 It is a schematic structural diagram of the quadriceps femoris simulation loader described in the present invention.

[0021] Figure 5 It is a schematic diagram of the structure of the robotic arm operating system described in the present invention.

[0022] Figure 6 It is a schematic structural diagram of the knee joint model described in the present invention.

[0023] Figure 7 It is a structural schematic diagram of the force / torque output system described in the present invention.

[0024] Figure 8 It is a schematic diagram of the internal and external rotation stiffness of the bionic tension-compression body joint described in the present invention.

[0025] Fig. 9 This is a schematic diagram of the inversion and varus stiffness of the bionic tension-compression joint described in the present invention.

[0026] Fig.10 It is a schematic diagram of the front-to-back translation stiffness of the bionic tension-compression body joint described in the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0028] like Figure 1-10 As shown, the present invention provides a joint stiffness testing device based on an optical platform, comprising: an optical platform system 100, a robot arm operating system 200, a knee joint model 300 and a force / torque output system 400, an optical platform 110, a connecting mechanism 120, a connecting base 121, a second sleeve screw hole 122, a first sleeve screw hole 123, a sleeve 124, a connecting roller 125, a connecting shaft 126, a supporting sheet 127, a quadriceps simulation loader 130, a loader pulley 131, a loader shaft 132, a loader Device base 133, hamstring simulation loader 140, host computer 201, sensor control box 202, connector 203, ATI sensor 204, power supply 205, connecting device 310, tibia model 320, patella model 330, femur model 340, third wrist joint 401, second wrist joint 402, elbow joint 403, first wrist joint 401, second shoulder joint 405, first shoulder joint 406, robotic arm base 407, bracket base 408, operation panel 409, robotic arm power box 410.

[0029] The optical platform system includes: an optical platform 110, a connecting mechanism 120 between the platform and the femoral model, a quadriceps simulation loader 130 and a hamstring simulation loader 140. Two hamstring simulation loaders 140, a connecting mechanism 120 and a quadriceps simulation loader 130 are sequentially arranged along the longitudinal midline of the optical platform 110; and a knee joint model 300 is fixedly arranged on the connecting mechanism 120. Among them, a central axis is selected on the platform, and the hamstring simulation loader 140, the connecting mechanism 120 between the platform and the femoral model, and the quadriceps simulation loader 130 are sequentially distributed on the central axis, and each device is axially symmetrical about the central axis. The hamstring simulation loader 140, the connecting mechanism 120 and the quadriceps simulation loader 130 are all provided with pulleys, which are arranged along the same straight line to control the direction of the muscle simulation force. When they are in the same straight line, the direction of the force loading can be ensured to be correct and smooth.

[0030] In the present invention, as a preference, the connection mechanism 120 between the platform and the femoral model is fixedly connected to the platform via five M6 screws.

[0031] The quadriceps simulation loader 130 and the hamstring simulation loader 140 are both composed of a base plate with a pulley. Each base plate is fixed to the optical platform 110 by 5 M6 screws, and one side of the loader pulley 131 of the quadriceps simulation loader 130 is close to the edge of the optical platform. There are two hamstring simulation loaders 140, one is arranged on the symmetrical edge of the quadriceps simulation loader 130, and one side of the connecting roller 125 is close to the edge of the optical platform; the other is arranged in front of the connecting mechanism 120, and one side of the connecting roller 125 is close to the connecting mechanism 120. Among them, the hamstring simulation loader 140 has the same structure as the quadriceps simulation loader 130, and both include: a loader base 133, which is fixedly connected to the optical platform 110, and the loader pulley 131 is rotatably supported and arranged on the loader base 133 through the loader shaft 132. The connecting mechanism 120 includes: a connecting base 121, a second sleeve screw hole 122, a first sleeve screw hole 123, a sleeve 124, a connecting roller 125, a connecting shaft 126, and a supporting plate 127, wherein the connecting base 121 is fixedly set on the optical platform 110, the sleeve 125 is fixedly set at one end of the connecting base 121, the femur model is set in the sleeve 124 for fixing the knee joint model, two supporting plates 127 are relatively fixedly set on the connecting base 121 and are located on one side of the sleeve 124, and the connecting roller 125 is rotatably supported and set between the two supporting plates 127.

[0032] The robot operating system 400 includes: an operation panel 409, a robot power box 410, a support base 408, a robot base 407, and a first shoulder joint 406, a second shoulder joint 405, an elbow joint 403, a first wrist joint 404, a second wrist joint 402, and a third wrist joint 401 connected in sequence. The robot base 407 needs to be parallel to the surface of the optical platform 110, as close as possible, and fixed on the ground. The robot base 407 is placed on the support base 408, and the position of the robot is adjusted so that the central axis passes through the center of the robot base 407, and the robot base joint is perpendicular to the horizontal plane of the optical platform. The operation panel 5 and the robot base 407 are connected to the robot power box 410 through wires, and the robot power box 410 is placed on the support base 408.

[0033] In the present invention, as a preferred embodiment, the robotic arm system comes from the Universal Robots collaborative robot series - the Universal Robots UR16e robot.

[0034] The knee joint model 300 is provided with a femur model 340, a patella model 330, a tibia model 320 and a connector 310 from one end to the other end, wherein the femur model 340, the tibia model 320 and the patella model 330 are connected by a ligament dedicated to the tension-compression robot. The connector 310 is fixedly connected to the tibia model 320 by a bolt.

[0035] The force / torque output system 200 includes: a connection device 203, an ATI sensor 204, a sensor control box Netbox 202, a power supply 205 and a host computer 201. The connection device 203 is fixedly connected to the ATI sensor 204 by bolts. The ATI sensor 204 is connected to the sensor control box Netbox 202 by a dedicated wire, and the sensor control box Netbox 202 is powered by a 24V regulated power supply 205. The data of the sensor is transmitted to the host computer 201 via a network cable through the sensor control box Netbox 202.

[0036] The present invention also provides a joint stiffness testing device and method based on an optical platform, comprising: The force data signal of the joint movement is collected by a six-dimensional force sensor, the collected signal is filtered and processed, and the position coordinates are converted into local coordinates; A real-time monitoring algorithm based on the Kalman filter is used to evaluate the real-time status of the tension and compression robot joints and calculate the real-time stiffness; Conduct error analysis on the calculation results and evaluate the reliability of the test results.

[0037] Specifically include: Step 1: Basic structure installation The knee joint of the bionic tensile-compression robot is connected to the device, the convex column of the femur in the knee joint model is inserted into the circular hole of the sleeve 124 of the connecting mechanism 120, and the screw hole in the column is aligned with the first sleeve screw hole 204, and the M4 screw and nut are screwed in, and the two second sleeve screw holes 122 on the side of the sleeve 124 are tightened by M3 screws, so as to ensure that the femoral joint is fixedly connected to the optical platform; the fishing line led out from the patella passes under the pulley and extends to the top of the pulley, and a weight is hung at the end to simulate the quadriceps muscle force. Similarly, the fishing line led out from the tibia passes through the two pulleys in the hamstring simulation loader and finally hangs down on the other side of the optical platform 110, and a weight is hung at the end to simulate the hamstring muscle force.

[0038] Step 2: Sensor Calibration Place the ATI sensor in a force-free state, that is, no external force is applied to the sensor. In this state, perform a zero-point calibration, return the measurement result to zero, and calibrate the sensor using known force or torque values, which can be obtained by using an object of known mass or a reference standard sensor. Apply different known force or torque values ​​and record the output of the sensor. Use the calibration data for data processing and calculate the calibration coefficients. Use linear interpolation or polynomial fitting methods to calculate the calibration coefficients based on the relationship between the measurement results and the known values; use a set of known force or torque values ​​for verification, and compare the measurement results with the known values ​​to ensure the accuracy of the calibration; if there is a large deviation, the sensor needs to be recalibrated; Step 3: Sensor connection After the sensor is calibrated, it is fixed to the tibial connection device through the three screws of the screw group; ensure that the power supply of the sensor is normal, select the communication interface of the sensor, and connect the communication cable of the sensor to the serial port of the host computer according to the selected communication interface; according to the specifications and application requirements of the sensor, set the sampling rate, filter settings and other parameters of the sensor through the software; Step 4: Connection of the Robotic Arm Make sure the power of the UR16e robot is connected and turned on. Connect the robot's controller to the power supply and ensure that the power supply is stable. Use an Ethernet cable to connect the robot's controller to the computer. Run UR's official software "URCaps" on the computer, which is a plug-in for controlling the UR robot. Select the correct robot model (here is UR16e) in URCaps and configure it. After the configuration is complete, the robot can be controlled through the graphical interface in URCaps or programming languages ​​(such as URScript). Connect the flange device to the end of the robot arm, adjust the robot arm to free motion mode, move the flange device to align it with the sensor, and then fix it to the sensor with the three screws of the screw group; Step 5. Initial Setup According to the position and posture of the robot arm, tibia model information, etc., the required local coordinate system information is calculated, and the local coordinate system information is input into the robot arm as the tool center point to provide a basis for subsequent motion settings; Step 6: Stiffness test Ensure that the robot arm is in a stable state and there are no loose or damaged parts. Ensure that safety measures have been taken to avoid any potential injuries. Determine the test parameters such as speed, force and angle range as needed. According to the test parameter settings, run the test program of the robot arm. The program will control the robot arm to move at the set speed, force and angle. During the test, input displacement information according to the local coordinate system so that the knee joint moves a certain displacement as required, and read the force data received in the ATI sensor on the host computer. Perform coordinate conversion and data processing, and use the data to draw torque-angle or force-displacement curves. The stiffness of the joint can be calculated by the slope of the curve. In order to ensure the accuracy and consistency of the data, repeat the test many times.

[0039] Example 1 Measuring the internal and external rotation stiffness of the knee joint at 30° flexion Connect the robot arm to the tension and compression knee joint model according to steps 1 to 5, adjust to the initial state, and set the ATI sensor to zero. Enter the position control command in the robot arm's operating system to make the knee joint model flex 30°. At this time, observe the ATI sensor data of the host computer and find that there are six degrees of freedom (respectively: , , , , and ) have data, and (bending direction) is greater than 0.5 N·m. At this time, set the robot arm to manual adjustment mode, fine-tune the position of the tool center, and observe the ATI sensor data of the host computer during the adjustment process so that the data If the value of (internal and external rotation direction) is within 0.2N·m, it is considered to be the natural position at 30° flexion, and the internal and external rotation of the knee joint is 0°. Set the ATI sensor to zero again, control the robot arm, and increase or decrease the internal and external rotation of the knee joint from 0° to plus or minus 14° at an increment of 0.5°. After each rotation, pause for 2 seconds to allow the sensor reading to stabilize, and then perform the next rotation. After the end, use the ATI sensor software of the host computer to export the sensor data for data processing. Record the value at each angle. Torque data, and finally draw the torque-rotation angle curve as shown Figure 8 As shown, according to the formula , the slope of the curve is the internal and external rotation stiffness of the knee joint at this moment. Similarly, the internal and external rotation stiffness of the tension-compression robot knee joint at different flexion angles can be measured.

[0040] Example 2 Measuring the stiffness of the knee joint in other degrees of freedom Connect the robot arm to the tension and compression knee joint model according to steps 1 to 5, adjust to the initial state, and set the ATI sensor to zero. Enter the position control command in the robot arm's operating system to flex the knee joint model by 30°. At this time, set the robot arm to manual adjustment mode and fine-tune the position of the tool center. During the adjustment process, observe the ATI sensor data of the host computer so that the data is If the value of (inside-outside rotation direction) is within 0.2N·m, it is considered to be the natural position at 30° flexion. At this time, the inside-outside rotation angle of the knee joint is 0°. The ATI sensor is set to zero again, and the robot arm is controlled to increase or decrease the inside-outside rotation of the knee joint from 0° to plus or minus 10° at an increment of 0.5°. After each rotation, the sensor reading is allowed to stabilize for 2 seconds before the next rotation is performed. After the end, the ATI sensor software of the host computer is used to export the sensor data, perform data processing, and record the value at each angle. Torque data, and finally draw the torque-rotation angle curve, such as Fig. 9 As shown, according to the formula , the slope of the curve is the varus-valgus stiffness of the knee joint at this moment. Similarly, the varus-valgus stiffness of the knee joint of the tension-compression robot at different flexion angles can be measured.

[0041] Example 3 Measuring the left-right translation stiffness of the knee joint of a tension-compression robot According to steps 1 to 5, connect the robot arm to the tension and compression body knee joint model, adjust to the initial state, set the ATI sensor to zero, input the position control command in the robot arm's operating system, and let the knee joint model bend 30°. At this time, set the robot arm to manual adjustment mode, fine-tune the position of the tool center, and observe the ATI sensor data of the host computer during the adjustment process so that the data If the value of (left-right translation direction) is within 0.5N, it is considered to be the natural position at 30° flexion. The left-right translation value of the knee joint is 0mm. Set the ATI sensor to zero again, control the robot arm, and increase or decrease the left-right translation value of the knee joint from 0mm to plus or minus 8mm at an increment of 0.4mm. After each translation, pause for 2 seconds to allow the sensor reading to stabilize, and then perform the next translation. After the end, use the ATI sensor software of the host computer to export the sensor data for data processing. Record the value of each displacement. Force data, and finally draw the force-displacement curve, such as Fig.10 As shown, according to the formula , the slope of the curve is the left-right translation stiffness of the knee joint at this moment. Similarly, the left-right translation stiffness of the knee joint of the tension-compression robot at different flexion angles can be measured.

[0042] Example 4 Measuring the left-right translation stiffness of the knee joint of the tension-compression robot at different flexion angles According to steps 1 to 5, connect the robot arm to the tension and compression body knee joint model, adjust to the initial state, set the ATI sensor to zero, input the position control command in the robot arm's operating system, and let the knee joint model bend 30°. At this time, set the robot arm to manual adjustment mode, fine-tune the position of the tool center, and observe the ATI sensor data of the host computer during the adjustment process so that the data If the value of (front-back translation direction) is within 0.5N, it is considered to be the natural position at 30° flexion. The front-back translation value of the knee joint is 0mm. Set the ATI sensor to zero again, control the robot arm, and increase or decrease the left-right translation value of the knee joint from 0mm to plus or minus 8mm at an increment of 0.4mm. After each translation, pause for 2 seconds to allow the sensor to stabilize before the next translation. After the end, use the ATI sensor software of the host computer to export the sensor data, perform data processing, and record the value of each displacement. Force data, and finally draw the force / displacement curve, according to the formula , the slope of the curve is the anterior-posterior translation stiffness of the knee joint at this moment. Similarly, the anterior-posterior translation stiffness of the knee joint of the tension-compression robot can be measured at different flexion angles.

[0043] Example 5 Measuring the axial tension and compression stiffness of the knee joint of a tension-compression robot According to steps 1 to 5, connect the robot arm to the tension and compression body knee joint model, adjust to the initial state, set the ATI sensor to zero, input the position control command in the robot arm's operating system, and let the knee joint model bend 30°. At this time, set the robot arm to manual adjustment mode, fine-tune the position of the tool center, and observe the ATI sensor data of the host computer during the adjustment process so that the data If the value (in the axial tension and compression direction) is within 0.5N, it is considered to be the natural position at 30° flexion. The axial translation value of the knee joint is 0mm. Reset the ATI sensor to zero again, manipulate the robotic arm, and increase the axial tensile displacement value of the knee joint from 0mm to 8mm at an increment of 0.4mm. After each translation, pause for 2 seconds to allow the sensor to stabilize before performing the next translation. After completion, use the ATI sensor software of the host computer to export the sensor data for data processing. After the stretching is completed, restore the knee joint to its natural position at 30° flexion. Reset the ATI sensor to zero again, manipulate the robotic arm, and reduce the axial tensile displacement value of the knee joint from 0mm to -1mm at an increment of 0.1mm. Record the value of each displacement. Force data, and finally draw the force / displacement curve, according to the formula , the slope of the curve is the axial tension and compression stiffness of the knee joint at this moment. Similarly, the axial tension and compression stiffness of the tension-compression robot knee joint at different flexion angles can be measured.

[0044] It can be seen from Examples 1-5 that the joint stiffness testing device and method based on an optical platform provided by the present invention can effectively measure the stiffness of the knee joint of a bionic tension and compression robot under different motion states. Examples 1-5 demonstrate the versatility and accuracy of the testing device, which can comprehensively evaluate the internal and external rotation, internal and external valgus, front and back left and right translation, and axial tension and compression stiffness of the knee joint. In Example 1, the internal and external rotation stiffness of the knee joint at this angle was tested by adjusting the knee joint model to a specific flexion angle and fine-tuning it using the robotic arm operating system. Example 2 measures the internal and external valgus stiffness of the knee joint, also at a specific flexion angle. Both examples illustrate that the testing device can accurately measure the rotational stiffness of the knee joint. Examples 3 and 4 respectively measure the left and right and front and back translation stiffness of the knee joint at a specific flexion angle. These two examples show that the testing device can not only evaluate the rotational stiffness, but also perform accurate stiffness tests on the translational motion of the knee joint. Finally, Example 5 focuses on measuring the axial tension and compression stiffness of the knee joint, by controlling the robotic arm to make the knee joint model perform axial tension and compression movements, and record the corresponding force data. This example further demonstrates the validity of the test device in evaluating the axial motion stiffness of the knee joint.

[0045] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A joint stiffness testing device based on an optical platform, characterized in that: include: An optical table system, the support of which is arranged on a horizontal plane, and comprises: A knee joint model, which is supported on the optical platform system and located at one end of the optical platform system; A force or torque output system, which is arranged on the upper part of the knee joint model; A robot arm operating system is arranged on a horizontal plane and is located at one end of the optical platform system, close to the knee joint model; The optical platform comprises: An optical platform, the support of which is arranged on a horizontal plane; The following are arranged in sequence along the longitudinal midline of the optical platform: two hamstring simulation loaders, connecting mechanisms, and a quadriceps simulation loader; The knee joint model is fixedly arranged on the connecting mechanism.

2. The joint stiffness testing device based on an optical platform according to claim 1, characterized in that: The hamstring simulation loader, the connection mechanism and the quadriceps simulation loader are all provided with pulleys, and the pulleys are located in the same straight line.

3. The joint stiffness testing device based on an optical platform according to claim 2, characterized in that: The knee joint model is sequentially provided with: a femur model, a patella model, a tibia model and a connecting device from one end to the other end.

4. The joint stiffness testing device based on an optical platform according to claim 3, characterized in that: The femur model is fixedly arranged on the connecting mechanism.

5. The joint stiffness testing device based on an optical platform according to claim 4, characterized in that: The robotic arm operating system comprises: A support base, which is arranged on a horizontal plane; A mechanical arm base, which is fixedly arranged at one end of the support base; A mechanical arm power supply box, which is fixedly arranged at the other end of the support base; The first shoulder joint, the second shoulder joint, the elbow joint, the first wrist joint, the second wrist joint and the third wrist joint are connected in sequence.

6. The joint stiffness testing device based on an optical platform according to claim 5, characterized in that: The hamstring muscle simulation loader has the same structure as the quadriceps femoris simulation loader, and both include: A loader base, which is fixedly connected to the optical platform; The loader pulley is rotatably supported on the loader base.

7. The joint stiffness testing device based on an optical platform according to claim 6, characterized in that: The connecting mechanism comprises: A connecting base, which is fixedly arranged on the optical platform; A sleeve, which is fixedly arranged at one end of the connecting base, and the femur model is fixedly arranged in the sleeve; Two supporting plates, which are relatively fixedly arranged on the connecting base and located on one side of the sleeve; A connecting roller is rotatably supported and arranged between the two supporting sheets.

8. A joint stiffness testing method based on an optical platform, characterized in that: The joint stiffness testing device based on an optical platform according to any one of claims 1 to 7 comprises: Initial setup: Mount the knee joint model on the optical platform system and make preliminary adjustments through the robotic arm operating system to ensure that the test device is in a stable state; Sensor calibration: Zero point calibration and calibration of the six-dimensional force sensor to ensure the accuracy of the measurement data; Data collection and processing: During the predetermined movement of the knee joint model, the force / torque data is collected through the sensor, filtered, and converted into values ​​in the local coordinate system; Real-time state evaluation and stiffness calculation: Use Kalman filter and real-time monitoring algorithm to evaluate the real-time state of the joint and calculate the stiffness of the joint under different motion states; Error analysis and result verification: Perform error analysis on the calculated stiffness value to verify the reliability of the test results, and ensure the consistency of the results through multiple tests.

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