Device and method for testing stiffness, accuracy and performance retention of an electric linear actuator

Abstract

The application discloses a kind of electric linear actuator rigidity, precision and its performance retention testing device and method, belong to equipment testing technical field.Device includes: support module, force loading module, measuring module and control module.Support module is used to fix the electric linear actuator to be measured and force loading module;Force loading module is equipped with servo motor cylinder, for being connected with the electric linear actuator to be measured, control module is used to control the movement of electric linear actuator to be measured and force loading module, and measuring module carries out data acquisition;Test method includes electric linear actuator rigidity test method, precision test method and its performance retention test method, using the testing device and method, once clamping can respectively carry out electric linear actuator rigidity, precision and its performance retention detection, and with the characteristics of high precision, high quasi reality.

Description

Technical Field

[0001] This invention belongs to the field of equipment testing technology, and in particular relates to a device and method for testing the stiffness, accuracy and performance retention of an electric linear actuator. Background Technology

[0002] Electric linear actuators, as a type of high-precision linear motion mechanism, are generally composed of servo motors, couplings, ball screw pairs, actuator rods, etc. They have the advantages of high motion accuracy, smooth motion, and high rigidity, and have been widely used in robotics, aerospace and other fields.

[0003] As the demand for electric linear actuators continues to increase, the performance requirements for them are also becoming increasingly stringent. Taking machining robots as an example, the stiffness, accuracy, and accuracy retention of the actuators have a significant impact on the overall stiffness, machining accuracy, and service life of the robot. Therefore, manufacturing actuators that meet these requirements is a necessary prerequisite for building high-performance robots and is currently a key research focus. Solving the manufacturing challenges of electric linear actuators requires both systematic design theory and relatively complete experimental testing techniques.

[0004] However, most current tests on the stiffness of electric linear actuators rely on manual loading or measurement, which suffers from low efficiency and low accuracy. Research on the stiffness and accuracy retention testing of electric linear actuators is still largely lacking.

[0005] In addition, existing electric linear actuator testing equipment is usually designed for only one test item. For tests of multiple performance aspects, different test systems often need to be designed, which to some extent leads to a waste of testing resources. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a testing device and method for the stiffness, accuracy, and performance retention of an electric linear actuator, thereby enabling the testing of the stiffness, accuracy, and performance retention of the electric linear actuator.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A testing device for the stiffness, accuracy, and performance retention of an electric linear actuator, comprising a support module, a force loading module, a measurement module, and a control module;

[0009] The support module is used to fix and install the electric linear actuator under test and the force loading module;

[0010] The force loading module includes a servo electric cylinder tooling plate, a servo electric cylinder, an electric cylinder connecting tooling, and an elastic loading device; the servo electric cylinder is fixed to the support module via the servo electric cylinder tooling plate; one end of the electric cylinder connecting tooling is connected to the servo electric cylinder, and the other end is connected to the elastic loading device; the elastic loading device is connected to the floating joint connecting tooling and is used to absorb the impact force during the loading process.

[0011] The measurement module includes a connector assembly, a sensor connection fixture, a floating joint connection fixture, an S-shaped tension / compression sensor, a floating joint, a fixed optical mirror group, a movable reflector, and a laser interferometer. The connector assembly is connected at both ends to the free end of the actuator rod of the electric linear actuator and the S-shaped tension / compression sensor, respectively. The sensor connection fixture is connected at both ends to the S-shaped tension / compression sensor and the floating joint, respectively. The floating joint is connected at both ends to a floating joint and an elastic loading device, respectively. The fixed optical mirror group, the movable reflector, and the laser interferometer are respectively connected to the motor base, the connector assembly, and the support module of the servo electric cylinder.

[0012] The control module is used to collect data from the actuator motor encoder, S-type tension / compression sensor and laser interferometer, and to control the movement of the servo motor and servo electric cylinder of the electric linear actuator under test.

[0013] A method for testing the stiffness of an electric linear actuator includes:

[0014] (1) Starting from the zero point of the electric linear actuator under test, set up S test points, and record the kth test point as Q. k ;

[0015] (2) Synchronously switch the servo electric cylinder and the electric linear actuator under test to the zero position of the electric linear actuator under test;

[0016] (3) The load on the electric linear actuator under test is increased to the specified maximum value at certain intervals. Each load value is held at pressure and each sample value is recorded. At the same time, the laser interferometer reading value corresponding to each load value is collected synchronously to obtain a set of data on the relationship between the loading force and deformation of the electric linear actuator.

[0017] Electric linear actuator loading force: f n =F n -F0;

[0018] Deformation: δ n =x n -x0;

[0019] In the formula: F0 and x0 are the readings of the S-type tension / compression sensor and the laser interferometer, respectively, when unloaded; F n For the nth sample value, x nThis is the nth reading value, where n = 1, 2, 3, ..., m, and m is the number of samples.

[0020] (4) Unload the electric linear actuator under test, and then load the electric linear actuator in the opposite direction. Repeat step (3) to obtain another set of data on the load force-deformation relationship of the electric linear actuator. According to the different directions of the two loads applied above, the two sets of data are regarded as the test results of the electric linear actuator under tension and compression respectively.

[0021] (5) Repeat the independent loading in both the tensile and compressive directions p times to obtain multiple sets of valid data;

[0022] (6) Use the motion control card to synchronously switch the servo electric cylinder and electric linear actuator to the next test point, and repeat steps (3)(4)(5) until valid data of all test points are obtained.

[0023] A method for testing the accuracy of an electric linear actuator includes:

[0024] (1) Set the measurement stroke, test speed, target position, and number of reciprocating strokes N of the electric linear actuator; set the servo electric cylinder to passive position following mode; set the data acquisition point position of the laser interferometer according to the target position;

[0025] (2) Start the electric linear actuator according to the set stroke, test speed, target position and number of reciprocations;

[0026] (3) After the electric linear actuator runs N reciprocating cycles according to the set stroke, the actual position reached by the electric linear actuator when it approaches the target position along the extension direction and the actual position reached when it approaches the target position along the retraction direction are obtained according to the measurement value of the laser interferometer during these N running cycles.

[0027] A method for testing the stiffness and accuracy retention of an electric linear actuator, comprising:

[0028] (1) Perform stiffness test, control the electric linear actuator under test to increase the load to the specified maximum value at certain intervals, and load the electric linear actuator in the opposite direction to complete the stiffness data acquisition of the electric linear actuator under test under tension and compression; perform accuracy test, control the measurement stroke, test speed, target position and number of reciprocating runs of the electric linear actuator under test, control the servo electric cylinder to the position passive following mode, and complete the data acquisition of positioning accuracy;

[0029] (2) Set the servo electric cylinder to a control mode of force active input and position passive following; set the running mileage or running time of the electric linear actuator in one operating cycle, as well as its test speed; input the load force to be applied;

[0030] (3) Start the electric linear actuator according to the set running mileage or running time and test speed; use the actuator motor encoder to read the rotation angle of the servo motor shaft, and use the S-type tension and compression sensor to collect the load applied by the servo electric cylinder to realize real-time monitoring of the electric linear actuator's operation process.

[0031] (4) After the electric linear actuator finishes running according to the set running mileage or running time, use stiffness test method and accuracy test method to test the stiffness value and accuracy value of the electric linear actuator after this running cycle.

[0032] (5) Repeat steps (2)(3)(4) to conduct stiffness and accuracy retention tests for the next operating cycle until the electric linear actuator fails to maintain its operating accuracy / stiffness or reaches the set cutoff mileage / time.

[0033] Compared with the prior art, the significant advantages of this invention are:

[0034] 1. The testing device of the present invention can realize automatic and continuous loading of load force during stiffness testing. The load applied by the servo electric cylinder is measured by an S-type tensile and compressive sensor, and the position information of the electric linear actuator under the corresponding load is measured by a laser interferometer, which ensures the accuracy of the loading force and deformation data.

[0035] 2. In the stiffness and accuracy retention test, due to the excellent dynamic performance of the servo electric cylinder, the force loading module of the test device of the present invention can apply a constant load or simulate the alternating load on the electric linear actuator in actual working conditions, thus ensuring the realism of the stiffness and accuracy retention test.

[0036] 3. The testing device of the present invention is provided with an elastic loading device between the electric linear actuator and the servo electric cylinder. The deformation of the disc spring is converted into a corresponding loading force through the elastic loading device, which can realize the precise loading of force and protect the testing device from large impacts and vibrations during loading and operation.

[0037] 4. The electric linear actuator stiffness, accuracy and performance retention testing device of the present invention has a simple structure, compact layout, real-time data monitoring, and is easy for testers to operate; at the same time, the use of a floating joint to connect the force loading module and the S-type tension and compression sensor can reduce the coaxiality requirement between the force loading module and the S-type tension and compression sensor to a certain extent.

[0038] 5. The testing device of the present invention can perform stiffness and accuracy tests on electric linear actuators, as well as stiffness and accuracy retention tests on electric linear actuators. The testing method is simple, and the stiffness, accuracy and performance retention tests of electric linear actuators can be carried out in one clamping. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the testing device for the stiffness, accuracy, and performance retention of the electric linear actuator of the present invention.

[0040] Figure 2 This is an exploded view of the connection structure of the measurement module of the present invention.

[0041] Figure 3 This is a schematic diagram of the elastic loading device of the present invention.

[0042] Figure 4 This is a schematic diagram of the control module of the electric linear actuator stiffness, accuracy and performance retention testing device of the present invention.

[0043] The meanings represented by the numbers in the diagram are as follows:

[0044] 1. Electric linear actuator; 2. Rear support for electric linear actuator; 3. Front support for electric linear actuator; 4. Movable reflector; 5. S-type tension / compression sensor; 6. Floating joint; 7. Floating joint connection fixture; 8. Elastic loading device; 9. Electric cylinder connection fixture; 10. Servo electric cylinder; 11. Fixed optical lens group; 12. Laser interferometer; 13. Servo electric cylinder fixture plate; 14. Sensor connection fixture; 15. Connector; 16. Lens base connection fixture; 17. Lens base; 18. Cast iron platform; 19. Actuator motor driver; 20. Actuator motor encoder; 21. Servo electric cylinder motor driver; 22. Motion control card; 23. Data acquisition system.

[0045] 81. Housing; 82. Front pressure pad; 83. Front support pad; 84. Rear support pad; 85. Rear pressure pad; 86. Push rod; 87. Disc spring. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0047] Combination Figure 1 The present invention provides a testing device for the stiffness, accuracy and performance retention of an electric linear actuator, comprising an electric linear actuator 1 under test, a support module, a force loading module, a measurement module and a control module.

[0048] The support module includes a cast iron platform 18, a front support seat 3 and a rear support seat 2 of the electric linear actuator, which are fixedly installed on the cast iron platform 18; the electric linear actuator 1 to be tested is fixedly installed on the front and rear support seats of the electric linear actuator.

[0049] The force loading module includes a servo electric cylinder tooling plate 13, a servo electric cylinder 10, an electric cylinder connecting tooling 9, and an elastic loading device 8; the servo electric cylinder tooling plate 13 is fixedly installed on the cast iron platform 18 by bolts; the servo electric cylinder 10 is fixedly connected to the servo electric cylinder tooling plate 13 by bolts; one end of the electric cylinder connecting tooling 9 is provided with an internal thread, which is connected to the external thread of the telescopic rod of the servo electric cylinder 10, and the other end is connected to the elastic loading device 8 by bolts;

[0050] Combination Figure 2 The measurement module includes a connector 15, a sensor connection fixture 14, a floating joint connection fixture 7, an S-type tension / compression sensor 5, a floating joint 6, a lens base connection fixture 16, a lens base 17, a fixed optical lens group 11, a movable reflector 4, and a laser interferometer 12. Both ends of the connector 15 have external threads. One end's external thread connects to the internal thread of the free end of the actuator rod of the electric linear actuator 1, securing the lens base connection fixture 16 between the actuator rod and the connector 15. The other end's external thread connects to the internal thread of one end of the S-type tension / compression sensor 5. Both ends of the sensor connection fixture 14 have external threads. One end's external thread connects to the internal thread of the other end of the S-type tension / compression sensor 5, and the other end's external thread connects to the internal thread of the floating joint 6. One end of the floating joint connection fixture 7 has an internal thread that connects to the external thread of the floating joint 6, and the other end has a through hole for connection to an elastic loading device via a nut. 8. Connection: The lens base 17 is fixed to the lens base connecting fixture 16 by bolts; the fixed optical lens group 11, the movable reflector 4, and the laser interferometer 12 are respectively attracted to the motor base of the servo electric cylinder 10, the lens base 17, and the cast iron platform 18 by magnetic bases; the monochromatic light emitted by the laser interferometer 12 passes through the beam splitter of the fixed optical lens group 11 to obtain a reflected beam and a transmitted beam. The reflected beam is reflected by the reflector of the fixed optical lens group 11 and returns to the beam splitter. The transmitted beam is reflected by the movable reflector 4 and also returns to the beam splitter. Thus, the reflected beam and the transmitted beam converge to produce interference fringes; when the movable reflector 4 has a displacement relative to the reflector of the fixed optical lens group 11, the change in light intensity of the interference fringes is converted into an electrical pulse signal by the photoelectric conversion element in the receiver of the laser interferometer 12. Then, the laser interferometer 12 calculates the displacement of the electric linear actuator 1 under test by the total number of pulses.

[0051] The control module includes an actuator motor driver 19 and an actuator motor encoder 20 connected to the electric linear actuator servo motor; a servo electric cylinder motor driver 21 connected to the servo electric cylinder 10 servo motor; a motion control card 22 connected to the actuator motor driver 19 and the servo electric cylinder motor driver 21; and a data acquisition system 23 connected to the actuator motor encoder 20, the S-type tension / compression sensor 5, and the laser interferometer 12.

[0052] Combination Figure 3 The elastic loading device is equipped with a disc spring 87 inside. By converting the elastic deformation of the disc spring 87 into a corresponding loading force, the force can be accurately loaded. At the same time, due to the strong buffering and vibration absorption capacity of the disc spring 87, the testing device can be protected from large impacts and vibrations during loading and operation.

[0053] The elastic loading device further includes a housing 81, a front pressure pad 82, a front support pad 83, a rear pressure pad 85, a rear support pad 84, and a push rod 86; the housing 81 is connected to one end of the electric cylinder connecting fixture 9; the push rod 86 passes through the housing 81 and is connected to the floating joint connecting fixture 7, and can move axially relative to the housing 81; the housing 81 has a cavity, and the push rod 86 has a shoulder, dividing the cavity inside the housing 81 into two mounting cavities; the front pressure pad 82 and the front support pad 83 are located in one of the mounting cavities, and a set of disc springs 87 are provided between them; the rear pressure pad 85 and the rear support pad 84 are located in the other mounting cavity, and a set of disc springs 87 are also provided between them; the front support pad 83 and the rear support pad 84 are close to the shoulder. When the servo electric cylinder telescopic rod extends, the rear pressure pad 85 moves with the housing 81 to compress the disc spring 87 on the same side, transferring the load corresponding to the deformation of the disc spring 87 to the rear support pad 84 and the push rod 86, thereby loading the compressive force onto the electric linear actuator 1; when the servo electric cylinder telescopic rod retracts, the front pressure pad 82 moves with the housing 81 to compress the disc spring 87 on the same side, transferring the load corresponding to the deformation of the disc spring 87 to the front support pad 83 and the push rod 86, thereby loading the tensile force onto the electric linear actuator 1.

[0054] Combination Figure 4 The present invention discloses a method for testing the stiffness, accuracy, and performance retention of an electric linear actuator. The method employs the aforementioned testing device for the stiffness, accuracy, and performance retention of the electric linear actuator. The testing method includes a method for testing the stiffness, accuracy, and performance retention of the electric linear actuator. The testing process includes two aspects: first, the installation of the electric linear actuator 1 under test, the support module, the force loading module, and the measurement module; and second, the separate testing and analysis of stiffness, accuracy, and the retention of both.

[0055] The installation of the electric linear actuator 1 under test, the support module, the force loading module, and the measurement module includes the following steps:

[0056] Step 1: Install the electric linear actuator under test: Adjust the distance between the front and rear support seats of the electric linear actuator 1 according to its dimensions. Securely install the electric linear actuator 1 onto the front and rear support seats using the hole-shaft fit between the front and rear support seats and the electric linear actuator 1. Then, secure the front and rear support seats onto the cast iron platform 18. Simultaneously, adjust the parallelism of the electric linear actuator 1 along the feed direction. After installing the electric linear actuator 1, run it back and forth several times.

[0057] Step 2: Install the force loading module and measurement module: Ensure that the S-type tension and compression sensor 5 and the actuator rod of the electric linear actuator 1 are coaxial and parallel to the direction of movement of the servo electric cylinder 10; install the laser interferometer 12, the fixed optical mirror group 11 and the movable reflector 4 according to the product technical requirements, and ensure that the measurement optical path is parallel to the axis of the actuator rod of the electric linear actuator 1.

[0058] Step 3: Eliminate installation gaps: After zeroing the position of the actuator rod of the electric linear actuator 1, perform a preload to eliminate installation gaps, and zero the reading of the laser interferometer 12, while recording the zero point position information;

[0059] The stiffness test and analysis of the electric linear actuator includes the following steps:

[0060] Step 1: Conduct stiffness testing:

[0061] (1) Starting from the zero point of the electric linear actuator 1 under test, set S test points, and record the kth test point as Q. k (k = 1 ~ S);

[0062] (2) Synchronously switch the servo electric cylinder 10 and the electric linear actuator 1 under test to the zero position of the electric linear actuator under test.

[0063] (3) Increase the load on the electric linear actuator 1 under test at certain intervals to the specified maximum value. Keep each load value constant for 30-60 seconds and record each sampled value F. n (n=1,2,3…,m), simultaneously acquiring the corresponding laser interferometer readings x for each load value. n (n=1,2,3…,m), a set of data on the force-deformation relationship of an electric linear actuator was obtained; where F n For the nth sample value, x n This represents the nth reading, and m is the number of samples.

[0064] The electric linear actuator has a loading force of: f n =F n-F0(n=1,2,3…,m);

[0065] Deformation: δ n =x n -x0(n=1,2,3…,m);

[0066] In the formula: F0 and x0 are the readings of the S-type tension / compression sensor 5 and the laser interferometer 12 when unloaded, respectively;

[0067] (4) Unload the electric linear actuator 1 to be tested, and then load the electric linear actuator 1 in the opposite direction. Repeat step (3) to obtain another set of data on the load force-deformation relationship of the electric linear actuator. According to the different directions of the two loads applied above, the two sets of data are regarded as the test results of the electric linear actuator under tension and compression respectively.

[0068] (5) Repeat the independent loading in both the tensile and compressive directions p times to obtain multiple sets of valid data;

[0069] (6) Use motion control card 22 to synchronously switch servo electric cylinder 10 and electric linear actuator 1 to the next test point, and repeat steps (3)(4)(5) until valid data of all test points are obtained.

[0070] Step 2: Calculate the stiffness values ​​of the electric linear actuator at each test point: Plot the stiffness values ​​of the electric linear actuator at each test point Q. k The force-deformation data curves under tension and compression conditions, and the average value obtained by linearly fitting the slopes of the p groups of force and deformation data under each condition, represent the electric linear actuator at the test point Q. k Stiffness value under the corresponding state.

[0071] The accuracy testing and analysis of the electric linear actuator includes the following steps:

[0072] Step 1: Conduct accuracy testing experiments.

[0073] (1) Set the measuring stroke, test speed, and target position P of the electric linear actuator 1. i (i = 1 ~ M) and the number of reciprocating runs N; set the servo electric cylinder 10 to the position passive following mode; set the data acquisition point position of the laser interferometer 12 according to the target position;

[0074] (2) Start the electric linear actuator 1 according to the set stroke, test speed, target position and number of reciprocations;

[0075] (3) After the electric linear actuator 1 has run N reciprocating cycles according to the set stroke, the actual position P reached by the electric linear actuator as it approaches the target position along the extension direction is obtained based on the measurement values ​​of the laser interferometer 12 during these N running cycles.ij ↑(i=1~M; j=1~N) and the actual position P reached by approaching the target position along the retraction direction. ij ↓(i=1~M; j=1~N); P ij ↑ represents the actual position reached by the electric linear actuator as it extends along the j-th edge towards the i-th target position, P. ij ↓ represents the actual position reached by the electric linear actuator when it retracts along the j-th path to approach the i-th target position, and M represents the number of target positions.

[0076] Step 2: Analysis of Positioning Accuracy and Repeatability of the Electric Linear Actuator: The above sets of data are processed, and based on the target position P of the electric linear actuator 1... i (i = 1 to M) and the actual position P measured within N reciprocating cycles. ij ↑ and P ij ↓(i=1~M;j=1~N), calculate the unidirectional positioning accuracy and repeatability of the electric linear actuator in the extension and retraction directions, as well as its bidirectional positioning accuracy and repeatability.

[0077] The unidirectional positioning accuracy in the extension direction:

[0078]

[0079] One-way positioning accuracy in the retraction direction:

[0080]

[0081] Bidirectional positioning accuracy:

[0082] Unidirectional repeatability of positioning in the extension direction: R↑=max[R i ↑];R i ↑ = 4S i ↑;

[0083] Unidirectional repeatability accuracy in the retraction direction: R↓=max[R i ↓];R i ↓ = 4S i ↓;

[0084] Bidirectional repeatability accuracy: R = max[R i ];

[0085]

[0086] In the formula: X ij ↑ and X ij↓ represent the positioning deviation of the electric linear actuator when it approaches the i-th target position along the extension and retraction directions for the j-th time, respectively; and S represents the average positioning deviation when approaching the i-th target position along the extension and retraction directions, respectively; i ↑ and S i ↓ represent the estimated repeatability of positioning as the target position approaches along the extension and retraction directions, respectively; R i ↑ and R i ↓ represent the repeatability accuracy when approaching the i-th target position along the extension and retraction directions, respectively; R i B represents the bidirectional repeatability accuracy of the i-th target position; i This represents the reverse difference value of the i-th target position.

[0087] The stiffness and accuracy retention test and analysis of the electric linear actuator includes the following steps:

[0088] Step 1: Conduct stiffness and accuracy retention tests.

[0089] (1) Using the electric linear actuator stiffness test method and accuracy test method, the initial stiffness value and accuracy value of electric linear actuator 1 are obtained by testing;

[0090] (2) Set the servo electric cylinder 10 to a control mode of force active input and position passive following; set the running mileage or running time of the electric linear actuator 1 in one running cycle, as well as its test speed; input the load force to be applied;

[0091] (3) Start the electric linear actuator 1 according to the set running mileage or running time and test speed; use the actuator motor encoder 20 to read the rotation angle of the servo motor shaft, and the S-type tension and compression sensor 5 to collect the load applied by the servo electric cylinder 10, so as to realize real-time monitoring of the running process of the electric linear actuator 1.

[0092] (4) After the electric linear actuator 1 finishes running according to the set running mileage or running time, the stiffness test method and accuracy test method of the electric linear actuator are used to test the stiffness value and accuracy value of the electric linear actuator 1 after this running cycle.

[0093] (5) Repeat steps (2)(3)(4) to conduct stiffness and accuracy retention tests for the next operating cycle until the electric linear actuator 1 fails to maintain its operating accuracy / stiffness or reaches the set cutoff mileage / time.

[0094] Step 2: Study on the stiffness and accuracy retention of the electric linear actuator: Plot the variation of stiffness and accuracy of electric linear actuator 1 with running mileage or running time throughout the entire test cycle, and study the stiffness and accuracy retention law of electric linear actuator 1.

[0095] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The structure and connection method of each component in the specific embodiments described above are merely illustrative and may be varied. All equivalent transformations or improvements made on the basis of the technical solution of the present invention should fall within the protection scope of the present invention.

Claims

1. A device for testing the stiffness, accuracy and performance retention of an electric linear actuator, characterized by, It includes a support module, a force loading module, a measurement module, and a control module; The support module is used to fix and install the electric linear actuator under test and the force loading module; The force loading module includes a servo electric cylinder tooling plate, a servo electric cylinder, an electric cylinder connecting tooling, and an elastic loading device; the servo electric cylinder is fixed to the support module via the servo electric cylinder tooling plate; one end of the electric cylinder connecting tooling is connected to the servo electric cylinder, and the other end is connected to the elastic loading device; the elastic loading device is connected to the floating joint connecting tooling and is used to absorb the impact force during the loading process. The measurement module includes a connector assembly, a sensor connection fixture, a floating joint connection fixture, an S-shaped tension / compression sensor, a floating joint, a fixed optical mirror group, a movable reflector, and a laser interferometer. The connector assembly is connected at both ends to the free end of the actuator rod of the electric linear actuator and the S-shaped tension / compression sensor, respectively. The sensor connection fixture is connected at both ends to the S-shaped tension / compression sensor and the floating joint, respectively. The floating joint is connected at both ends to a floating joint and an elastic loading device, respectively. The fixed optical mirror group, the movable reflector, and the laser interferometer are respectively connected to the motor base, the connector assembly, and the support module of the servo electric cylinder. The control module is used to collect data from the actuator motor encoder, S-type tension and compression sensor and laser interferometer, and to control the movement of the tested electric linear actuator servo motor and servo electric cylinder. The elastic loading device includes a housing, a front pressure pad, a front support pad, a rear pressure pad, a rear support pad, a push rod, and disc springs. The housing is connected to one end of an electric cylinder connecting fixture. The push rod passes through the housing and is connected to a floating joint connecting fixture, allowing it to move axially relative to the housing. The housing has a cavity, and the push rod has a shoulder, dividing the cavity into two mounting cavities. The front pressure pad and the front support pad are located in one of the mounting cavities, with a set of disc springs between them. The rear pressure pad and the rear support pad are located in the other mounting cavity, with another set of disc springs between them. The front support pad and the rear support pad are located near the shoulder.

2. The device for testing the stiffness, accuracy and performance retention of an electric linear actuator according to claim 1, characterized in that, The connector assembly includes a connector, a lens base connecting fixture, and a lens base; both ends of the connector are provided with external threads, one end of which is connected to the internal thread of the free end of the electric linear actuator rod, fastening the lens base connecting fixture between the actuator rod and the connector, and the other end of which is connected to the internal thread of one end of the S-type tension and compression sensor; the lens base is fixed to the lens base connecting fixture.

3. The device for testing the stiffness, accuracy and performance retention of an electric linear actuator according to claim 1, wherein The support module includes a platform, a front support base for the electric linear actuator and a rear support base for the electric linear actuator, which are fixedly installed on the platform; the electric linear actuator under test is fixedly installed on the front and rear support bases for the electric linear actuator.

4. The testing device for the stiffness, accuracy, and performance retention of an electric linear actuator according to claim 1, characterized in that, The control module includes an actuator motor driver and an actuator motor encoder connected to the electric linear actuator servo motor, a servo electric cylinder motor driver connected to the servo electric cylinder servo motor, a motion control card connected to the actuator motor driver and the servo electric cylinder motor driver, and a data acquisition system connected to the actuator motor encoder, the S-type tension / compression sensor and the laser interferometer.

5. A method for testing the stiffness of an electric linear actuator, characterized in that, The electric linear actuator stiffness, accuracy, and performance retention testing device according to any one of claims 1-4 includes: (1) Starting from the zero point of the electric linear actuator under test, set up S test points, and record the k-th test point as . ; (2) Synchronously switch the servo electric cylinder and the electric linear actuator under test to the zero position of the electric linear actuator under test; (3) The load on the electric linear actuator under test is increased to the specified maximum value at certain intervals. Each load value is held at pressure and each sample value is recorded. At the same time, the laser interferometer reading value corresponding to each load value is collected synchronously to obtain a set of data on the relationship between the loading force and deformation of the electric linear actuator. Electric linear actuator loading force: ; Transformation: ; In the formula: and These are the readings from the S-type tension / compression sensor and the laser interferometer, respectively, when unloaded. For the nth sample value, For the nth read value, m is the number of samples; (4) Unload the electric linear actuator under test, and then load the electric linear actuator in the opposite direction. Repeat step (3) to obtain another set of data on the load force-deformation relationship of the electric linear actuator. According to the different directions of the two loads applied above, the two sets of data are regarded as the test results of the electric linear actuator under tension and compression respectively. (5) Repeat the loading process independently p times in both the tensile and compressive directions to obtain multiple sets of valid data; (6) Use the motion control card to synchronously switch the servo electric cylinder and electric linear actuator to the next test point, and repeat steps (3), (4) and (5) until valid data for all test points are obtained.

6. A method for testing the accuracy of an electric linear actuator, characterized in that, The electric linear actuator stiffness, accuracy, and performance retention testing device according to any one of claims 1-4 includes: (1) Set the measurement stroke, test speed, target position, and number of reciprocating strokes N of the electric linear actuator; set the servo electric cylinder to position passive following mode; set the data acquisition point position of the laser interferometer according to the target position; (2) Start the electric linear actuator according to the set stroke, test speed, target position and number of reciprocations; (3) After the electric linear actuator runs N reciprocating cycles according to the set stroke, the actual position reached by the electric linear actuator when it approaches the target position along the extension direction and the actual position reached when it approaches the target position along the retraction direction are obtained according to the measurement value of the laser interferometer during these N running cycles.

7. The method for testing the accuracy of an electric linear actuator according to claim 6, characterized in that, Also includes: Calculate the unidirectional positioning accuracy and repeatability of the tested electric linear actuator in the extension and retraction directions, as well as its bidirectional positioning accuracy and repeatability: Unidirectional positioning accuracy in the extension direction: ; ， ， ； One-way positioning accuracy in the retraction direction: ; ， ， ； Bidirectional positioning accuracy: ; Unidirectional repeatability of positioning in the extension direction: ; ; Unidirectional repeatability accuracy in the retraction direction: ; ; Bidirectional repeatability accuracy: ; ， ； In the formula and These represent the positioning deviations of the electric linear actuator when it approaches the i-th target position along the extension and retraction directions for the j-th time, respectively. and These represent the average positioning deviations when approaching the i-th target position along the extension and retraction directions, respectively. and These represent the estimated repeatability accuracy values ​​when approaching the i-th target position along the extension and retraction directions, respectively. and These represent the repeatability accuracy when approaching the i-th target position along the extension and retraction directions, respectively. This represents the bidirectional repeatability accuracy of the i-th target position; This represents the reverse difference value of the i-th target position.

8. A method for testing the stiffness and accuracy retention of an electric linear actuator, characterized in that, The electric linear actuator stiffness, accuracy, and performance retention testing device according to any one of claims 1-4 includes: (1) Perform stiffness test, control the electric linear actuator under test to increase the load to the specified maximum value at certain intervals, and load the electric linear actuator in the opposite direction to complete the stiffness data acquisition of the electric linear actuator under test under tension and compression; perform accuracy test, control the measurement stroke, test speed, target position and number of reciprocating runs of the electric linear actuator under test, control the servo electric cylinder to the position passive following mode, and complete the data acquisition of positioning accuracy; (2) Set the servo electric cylinder to a control mode of force active input and position passive following; set the running mileage or running time of the electric linear actuator in one running cycle, as well as its test speed; input the load force to be applied; (3) Start the electric linear actuator according to the set running mileage or running time and test speed; use the actuator motor encoder to read the rotation angle of the servo motor shaft, and use the S-type tension and compression sensor to collect the load applied by the servo electric cylinder to realize real-time monitoring of the electric linear actuator's operation process. (4) After the electric linear actuator finishes running according to the set running mileage or running time, use stiffness test method and accuracy test method to test the stiffness value and accuracy value of the electric linear actuator after this running cycle. (5) Repeat steps (2), (3) and (4) to conduct stiffness and accuracy retention tests for the next operating cycle until the electric linear actuator fails to maintain its operating accuracy / stiffness or reaches the set cutoff mileage / time.

9. The testing device for the stiffness, accuracy, and performance retention of an electric linear actuator according to any one of claims 1-4, wherein the installation method comprises: Step 1: Install the support module and the electric linear actuator under test: Fix the electric linear actuator under test on the support module and adjust the parallelism of the electric linear actuator under test along the feed direction; After installing the electric linear actuator under test, run the electric linear actuator back and forth several times. Step 2: Install the force loading module and measurement module: Ensure that the S-type tension and compression sensor and the actuator rod of the electric linear actuator under test are coaxial and parallel to the direction of movement of the servo electric cylinder; install the laser interferometer, fixed optical lens group and movable reflector, and ensure that the measurement optical path is parallel to the axis of the actuator rod of the electric linear actuator under test; Step 3: Eliminate installation gaps: After zeroing the position of the electric linear actuator rod, perform a preload to eliminate installation gaps, and zero the laser interferometer reading, while recording the zero point position information.

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