Device and method for testing rigidity, precision and performance retentivity of electric linear actuator

Abstract

The invention discloses a device and a method for testing rigidity, precision and performance retentivity of an electric linear actuator, and belongs to the technical field of equipment testing. The device comprises a supporting module, a force loading module, a measuring module and a control module. The supporting module is used for fixing the to-be-tested electric linear actuator and the force loading module; the force loading module is provided with a servo electric cylinder and is used for being connected with a to-be-tested electric linear actuator, the control module is used for controlling the to-be-tested electric linear actuator and the force loading module to move, and the measuring module is used for collecting data; the testing method comprises an electric linear actuator rigidity testing method, an electric linear actuator precision testing method and an electric linear actuator performance retentivity testing method, by means of the testing device and the testing method, the rigidity, the precision and the performance retentivity of the electric linear actuator can be detected through one-time clamping, and the testing device and the testing method have the advantages of being high in precision and real degree.

Description

Technical Field

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

[0002] Electric linear actuators, as a 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. They have been widely used in robotics, aerospace and other fields.

[0003] As the demand for electric linear actuators continues to increase, the requirements for their performance are becoming increasingly stringent. Taking processing robots as an example, the stiffness, accuracy and accuracy retention of the actuator have a huge impact on the stiffness, processing accuracy and service life of the robot as a whole. Therefore, manufacturing actuators that meet the above-mentioned index requirements is a necessary prerequisite for building high-performance robots and is also the focus of current research. To solve the manufacturing problems of the above-mentioned electric linear actuators, both systematic design theory and relatively complete experimental testing technology are required.

[0004] However, the current stiffness test of electric linear actuators mostly adopts manual loading or manual measurement, which has problems such as low efficiency and low precision to a certain extent; there is still a large gap in the research on the stiffness and precision retention test of electric linear actuators.

[0005] In addition, existing electric linear actuator test devices are usually designed for only one test content, and different test systems are often designed for testing multiple performances, which to a certain extent causes a waste of test resources. Summary of the invention

[0006] In view of the above problems, the present invention provides a device and method for testing the stiffness, precision and performance retention of an electric linear actuator, so as to complete the testing of the stiffness, precision and performance retention of an electric linear actuator.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A device for testing the stiffness, precision 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 the electric linear actuator to be tested and the force loading module;

[0010] The force loading module comprises a servo electric cylinder fixture plate, a servo electric cylinder, an electric cylinder connecting fixture and an elastic loading device; the servo electric cylinder is fixed to the support module through the servo electric cylinder fixture plate; one end of the electric cylinder connecting fixture 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 fixture to absorb the impact force during the loading process;

[0011] The measuring module comprises a connector assembly, a sensor connection fixture, a floating joint connection fixture, an S-type tension and pressure sensor, a floating joint, a fixed optical lens group, a movable reflector and a laser interferometer; the two ends of the connector assembly are respectively connected to the free end of the actuating rod of the electric linear actuator and the S-type tension and pressure sensor; the two ends of the sensor connection fixture are respectively connected to the S-type tension and pressure sensor and the floating joint; the two ends of the floating joint are respectively connected to the floating joint and the elastic loading device; the fixed optical lens group, the movable reflector and the laser interferometer are respectively connected to the motor seat, 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, the S-type tension and pressure sensor and the laser interferometer and control the movement of the servo motor and the servo electric cylinder of the electric linear actuator under test.

[0013] A method for testing stiffness of an electric linear actuator, comprising:

[0014] (1) Starting from the zero position of the electric linear actuator to be tested, set S test points and record the kth test point as Q k ;

[0015] (2) Synchronously switching the servo electric cylinder and the electric linear actuator to be tested to the zero position of the electric linear actuator to be tested;

[0016] (3) The load of the electric linear actuator to be tested is increased at a certain interval value to a specified maximum value, and the pressure is maintained at each load value. Each sampled value is recorded, and the laser interferometer reading corresponding to each load value is synchronously collected to obtain a set of data on the corresponding relationship between the load force and deformation of the electric linear actuator;

[0017] Electric linear actuator loading force: f n =F n -F 0 ;

[0018] Deformation: δ n =x n -x 0 ;

[0019] Where: F 0 and x 0are the readings of the S-type tension and pressure sensor and the laser interferometer when there is no load; F n is the nth sampling value, x n is the nth reading value, n=1,2,3…,m, m is the number of samples;

[0020] (4) Unloading the electric linear actuator to be tested, then loading the electric linear actuator in the opposite direction, repeating step (3), and obtaining another set of data on the corresponding relationship between the loading force and the deformation of the electric linear actuator. According to the difference in the directions of the two load applications, 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 p times in the tension and compression directions to obtain multiple sets of valid data;

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

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

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

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

[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 in the extending direction approaching the target position and the actual position reached by the electric linear actuator in the retracting direction approaching the target position are obtained based on the measurement values ​​of the laser interferometer during these N operating cycles.

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

[0028] (1) Conduct stiffness test, control the electric linear actuator to increase the load to the specified maximum value at a certain interval value, and load the electric linear actuator in the opposite direction to complete the stiffness data collection of the electric linear actuator under tension and compression; conduct accuracy test, control the measurement stroke, test speed, target position and number of reciprocating operations of the electric linear actuator to be tested, control the servo electric cylinder to the position passive following mode, and complete the positioning accuracy data collection;

[0029] (2) Set the servo electric cylinder to a control mode where force is actively input and position is passively followed; set the running mileage or running time of the electric linear actuator within 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 the S-type tension and pressure sensor to collect the load applied by the servo electric cylinder to achieve real-time monitoring of the running process of the electric linear actuator;

[0031] (4) After the electric linear actuator has finished running according to the set running mileage or running time, the stiffness test method and the accuracy test method are used to test the stiffness value and accuracy value of the electric linear actuator after this running cycle;

[0032] (5) Repeat steps (2), (3), and (4) to carry out the stiffness and accuracy retention test for the next operating cycle until the operating accuracy / stiffness of the electric linear actuator fails or the set cut-off mileage / time is reached.

[0033] Compared with the prior art, the present invention has the following significant advantages:

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

[0035] 2. When testing the stiffness and precision retention of the test device of the present invention, due to the excellent dynamic performance of the servo electric cylinder, the force loading module can not only apply a constant load, but also simulate the alternating load on the electric linear actuator in actual working conditions, thereby ensuring the simulation of the stiffness and precision retention test;

[0036] 3. The test 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, so that accurate force loading can be achieved and the test device can be protected 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, and real-time data monitoring, which is convenient for testers to operate. At the same time, a floating joint is used to connect the force loading module and the S-type tension and pressure sensor, which can reduce the coaxiality requirement between the force loading module and the S-type tension and pressure sensor to a certain extent.

[0038] 5. The test device of the present invention can not only implement the stiffness and precision test of the electric linear actuator, but also conduct the stiffness and precision retention test of the electric linear actuator. Moreover, the test method is simple, and the stiffness, precision and performance retention of the electric linear actuator can be respectively tested with one clamping. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0042] Figure 4 FIG. is a schematic diagram of the control module of the test device for the stiffness, precision and performance retention of the electric linear actuator of the present invention.

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

[0044] 1. Electric linear actuator, 2. Rear support seat of electric linear actuator, 3. Front support seat of electric linear actuator, 4. Moving mirror, 5. S-type tension and compression sensor, 6. Floating joint, 7. Floating joint connection tooling, 8. Elastic loading device, 9. Electric cylinder connection tooling, 10. Servo electric cylinder, 11. Fixed optical lens group, 12. Laser interferometer, 13. Servo electric cylinder tooling plate, 14. Sensor connection tooling, 15. Connector, 16. Lens base connection tooling, 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 gasket, 83. Front support gasket, 84. Rear support gasket, 85. Rear pressure gasket, 86. Push rod, 87. Disc spring. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings:

[0047] Combined with Figure 1 , a test device for the stiffness, precision and performance retention of an electric linear actuator of the present invention includes a to-be-tested electric linear actuator 1, a support module, a force loading module, a measurement module and a control module.

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

[0049] The force loading module includes a servo electric cylinder fixture plate 13, a servo electric cylinder 10, an electric cylinder connecting fixture 9 and an elastic loading device 8; the servo electric cylinder fixture plate 13 is fixedly mounted on the cast iron platform 18 by bolts; the servo electric cylinder 10 is fixedly connected to the servo electric cylinder fixture plate 13 by bolts; one end of the electric cylinder connecting fixture 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 measuring module includes a connector 15, a sensor connecting fixture 14, a floating joint connecting fixture 7, an S-type tension and pressure sensor 5, a floating joint 6, a lens base connecting 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 are provided with external threads, the external thread at one end is connected to the internal thread of the free end of the actuating rod of the electric linear actuator 1, the lens base connecting fixture 16 is fastened between the actuating rod and the connector 15, and the external thread at the other end is connected to the internal thread at one end of the S-type tension and pressure sensor 5; both ends of the sensor connecting fixture 14 are provided with external threads, the external thread at one end is connected to the internal thread at the other end of the S-type tension and pressure sensor 5, and the external thread at the other end is connected to the internal thread of the floating joint 6; one end of the floating joint connecting fixture 7 is provided with an internal thread, which is connected to the external thread of the floating joint 6, and the other end is provided with a through hole, which is connected to the elastic loading device through a nut. 8 connection; the lens base 17 is fixedly connected to the lens base connecting tooling 16 by bolts; the fixed optical lens group 11, the movable reflector 4 and the laser interferometer 12 are respectively adsorbed on the motor base, the lens base 17 and the cast iron platform 18 of the servo electric cylinder 10 through magnetic table 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 light beam and a transmitted light beam, the reflected light beam is reflected by the reflector of the fixed optical lens group 11 and then returns to the beam splitter, and the transmitted light beam is reflected by the movable reflector 4 and then returns to the beam splitter, so that the reflected light beam and the transmitted light beam converge together to generate interference fringes; when the movable reflector 4 has a displacement change relative to the reflector of the fixed optical lens group 11, the light intensity change of the interference fringes is converted into an electrical pulse signal by the photoelectric conversion element in the receiver of the laser interferometer 12, and then the laser interferometer 12 calculates the displacement of the electric linear actuator 1 to be tested 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 motor of the servo electric cylinder 10; 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 and pressure sensor 5 and the laser interferometer 12.

[0052] Combination Figure 3 The elastic loading device is provided with a disc spring 87 inside, and the precise loading of force is achieved by converting the elastic deformation of the disc spring 87 into the corresponding loading force. At the same time, due to the strong buffering and vibration absorption ability of the disc spring 87, the test device can be protected from large impacts and vibrations during loading and operation.

[0053] The elastic loading device also includes a shell 81, a front pressure gasket 82, a front support gasket 83, a rear pressure gasket 85, a rear support gasket 84, and a push rod 86; the shell 81 is connected to one end of the electric cylinder connecting tool 9; the push rod 86 passes through the shell 81 and is connected to the floating joint connecting tool 7, and can move axially relative to the shell 81; a cavity is provided in the shell 81, and the push rod 86 is provided with a shaft shoulder, which divides the cavity in the shell 81 into two installation cavities, the front pressure gasket 82 and the front support gasket 83 are located in one of the installation cavities, and a group of disc springs 87 are provided between the two; the rear pressure gasket 85 and the rear support gasket 84 are located in the other installation cavity, and a group of disc springs 87 are also provided between the two; the front support gasket 83 and the rear support gasket 84 are close to the shaft shoulder. When the telescopic rod of the servo electric cylinder is extended, the rear pressure gasket 85 moves with the housing 81 to compress the disc spring 87 on the same side, and transfers the load corresponding to the deformation of the disc spring 87 to the rear support gasket 84 and the push rod 86, thereby realizing the loading of the compression force on the electric linear actuator 1; when the telescopic rod of the servo electric cylinder is retracted, the front pressure gasket 82 moves with the housing 81 to compress the disc spring 87 on the same side, and transfers the load corresponding to the deformation of the disc spring 87 to the front support gasket 83 and the push rod 86, thereby realizing the loading of the tensile force on the electric linear actuator 1.

[0054] Combination Figure 4 The present invention provides a method for testing the stiffness, precision and performance retention of an electric linear actuator. The device for testing the stiffness, precision and performance retention of an electric linear actuator is used. The testing method includes a method for testing the stiffness, precision and performance retention of an electric linear actuator. The testing process includes two aspects: one is the installation of the electric linear actuator 1 to be tested, the support module, the force loading module and the measurement module; the other is to carry out testing and analysis of the stiffness, precision and the retention of the two.

[0055] The installation of the electric linear actuator 1 to be tested, the support module, the force loading module and the measuring module comprises the following steps:

[0056] Step 1: Install the electric linear actuator to be tested: According to the size of the electric linear actuator 1 to be tested, adaptively adjust the distance between the front and rear support seats of the electric linear actuator, and through the hole-shaft matching between the front and rear support seats of the electric linear actuator and the electric linear actuator 1, fix the electric linear actuator 1 to be tested on the front and rear support seats of the electric linear actuator, and fix the front and rear support seats of the electric linear actuator on the cast iron platform 18, and adjust the parallelism of the electric linear actuator 1 along the feed direction. After installing the electric linear actuator 1 to be tested, run the electric linear actuator 1 back and forth several times;

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

[0058] Step 3, eliminating the installation gap: after the position of the actuator rod of the electric linear actuator 1 is adjusted to zero, a pre-compression is performed to eliminate the installation gap, and the reading of the laser interferometer 12 is cleared to zero, and the zero point position information is recorded at the same time;

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

[0060] Step 1: Conduct stiffness test:

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

[0062] (2) Synchronously switching the servo electric cylinder 10 and the electric linear actuator 1 to be tested to the zero position of the electric linear actuator to be tested;

[0063] (3) Increase the load of the electric linear actuator 1 to be tested to the specified maximum value at a certain interval. Each load value is kept constant for 30-60 seconds, and each sample value F is recorded. n (n=1,2,3…,m), and simultaneously collect the laser interferometer 12 readings x corresponding to each load value n (n=1,2,3…,m), and obtain a set of data on the corresponding relationship between loading force and deformation of the electric linear actuator; where F n is the nth sampling value, x n is the nth reading value, and m is the number of samples.

[0064] The electric linear actuator loading force: f n =Fn -F 0 (n=1,2,3…,m);

[0065] Deformation: δ n =x n -x 0 (n=1,2,3…,m);

[0066] Where: F 0 and x 0 are respectively the reading values ​​of the S-type tension and pressure sensor 5 and the laser interferometer 12 when there is no loading;

[0067] (4) Unloading the electric linear actuator 1 to be tested, then loading the electric linear actuator 1 in the opposite direction, repeating step (3), and obtaining another set of data on the corresponding relationship between the loading force and the deformation of the electric linear actuator. According to the difference in the directions of the two load applications, 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 p times in the tension and compression directions to obtain multiple sets of valid data;

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

[0070] Step 2: Calculate the stiffness value of each test point of the electric linear actuator: Draw the stiffness value of the electric linear actuator at the test point Q k Loading force-deformation data curve under tension and compression state. The average value obtained after linear fitting slope of p groups of loading force and deformation data under each state is the electric linear actuator at the test point Q. k Stiffness value in the corresponding state.

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

[0072] Step 1: Conduct accuracy test:

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

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

[0075] (3) After the electric linear actuator 1 runs N reciprocating cycles according to the set stroke, the actual position P reached by the electric linear actuator in the extension direction approaching the target position is obtained based on the measurement value of the laser interferometer 12 during these N operating cycles. ij ↑(i=1~M;j=1~N) and the actual position P reached along the retracting direction approaching the target position ij ↓(i=1~M; j=1~N); P ij ↑ is the actual position reached by the electric linear actuator when it extends for the jth time to approach the i-th target position, P ij ↓ is the actual position reached by the electric linear actuator when it retracts for the jth time to approach the i-th target position, and M is the number of target positions.

[0076] Step 2: Analysis of positioning accuracy and repeatability of the electric linear actuator: Process the above data sets and calculate the target position P of the electric linear actuator 1. i (i = 1 ~ M) and the actual position P measured in N reciprocating cycles ij ↑ and P ij ↓(i=1~M;j=1~N), calculate the one-way positioning accuracy and repeat positioning accuracy of the electric linear actuator in the extension and retraction directions, as well as its two-way positioning accuracy and repeat positioning accuracy;

[0077] One-way positioning accuracy in the extension direction:

[0078]

[0079] One-way positioning accuracy in retracting direction:

[0080]

[0081] Bidirectional positioning accuracy:

[0082] One-way repeat positioning accuracy in the extension direction: R↑=max[R i ↑]; R i ↑=4S i ↑;

[0083] One-way repeat positioning accuracy in retracting direction: R↓=max[R i ↓]; R i ↓=4S i ↓;

[0084] Bidirectional repeat positioning accuracy: R = max[R i ];

[0085]

[0086] Where: X ij ↑ and X ij ↓represents the positioning deviation of the electric linear actuator when it approaches the i-th target position in the extension and retraction directions for the jth time; and They represent the average positioning deviation when approaching the i-th target position along the extension and retraction directions respectively; S i ↑ and S i ↓ represent the estimated values ​​of repeatability when approaching the i-th target position along the extension and retraction directions; R i ↑ and R i ↓ represents the repeatability accuracy when approaching the i-th target position along the extension and retraction directions; R i represents the bidirectional repeatability of the i-th target position; B i Represents the reverse difference of the i-th target position.

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

[0088] Step 1: Conduct stiffness and precision retention test:

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

[0090] (2) Setting the servo electric cylinder 10 to a control mode in which force is actively input and position is passively followed; setting the running mileage or running time of the electric linear actuator 1 within one running cycle, as well as its test speed; inputting the load force to be applied;

[0091] (3) starting the electric linear actuator 1 according to the set running mileage or running time and test speed; using the actuator motor encoder 20 to read the rotation angle of the servo motor shaft, and the S-type tension and pressure 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 has finished running according to the set running mileage or running time, the stiffness value and the accuracy value of the electric linear actuator 1 after this running cycle are tested using the electric linear actuator stiffness test method and the accuracy test method;

[0093] (5) Repeat steps (2), (3), and (4) to carry out the stiffness and accuracy retention test of the next operation cycle until the operation accuracy / stiffness of the electric linear actuator 1 fails or the set cut-off mileage / time is reached;

[0094] Step 2: Study on the stiffness and precision retention of the electric linear actuator: Draw a graph showing the change pattern of the stiffness and precision of the electric linear actuator 1 with the running mileage or running time during the entire test cycle, and study the stiffness and precision retention pattern of the 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 above-mentioned specific embodiments. The structures, connection methods, etc. of the various components in the above-mentioned specific embodiments are merely schematic and are subject to change. Any equivalent changes or improvements made on the basis of the technical solution of the present invention should fall within the scope of protection of the present invention.

Claims

1. A device for testing the stiffness, accuracy and performance retention of an electric linear actuator, characterized in that: It includes a support module, a force loading module, a measurement module and a control module; The support module is used to fix the electric linear actuator to be tested and the force loading module; The force loading module comprises a servo electric cylinder fixture plate, a servo electric cylinder, an electric cylinder connecting fixture and an elastic loading device; the servo electric cylinder is fixed to the support module through the servo electric cylinder fixture plate; one end of the electric cylinder connecting fixture 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 fixture to absorb the impact force during the loading process; The measuring module comprises a connector assembly, a sensor connection fixture, a floating joint connection fixture, an S-type tension and pressure sensor, a floating joint, a fixed optical lens group, a movable reflector and a laser interferometer; the two ends of the connector assembly are respectively connected to the free end of the actuating rod of the electric linear actuator and the S-type tension and pressure sensor; the two ends of the sensor connection fixture are respectively connected to the S-type tension and pressure sensor and the floating joint; the two ends of the floating joint are respectively connected to the floating joint and the elastic loading device; the fixed optical lens group, the movable reflector and the laser interferometer are respectively connected to the motor seat, 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, the S-type tension and pressure sensor and the laser interferometer and control the movement of the servo motor and the servo electric cylinder of the electric linear actuator under test.

2. The electric linear actuator stiffness, precision and performance retention testing device according to claim 1, characterized in that: The elastic loading device includes a shell, a front pressure gasket, a front support gasket, a rear pressure gasket, a rear support gasket, a push rod and a disc spring; the shell is connected to one end of the electric cylinder connecting tooling; the push rod passes through the shell and is connected to the floating joint connecting tooling, and can move axially relative to the shell; a cavity is provided in the shell, and the push rod is provided with a shaft shoulder, which divides the cavity in the shell into two installation cavities, the front pressure gasket and the front support gasket are located in one of the installation cavities, and a group of disc springs are provided between the two; the rear pressure gasket and the rear support gasket are located in the other installation cavity, and a group of disc springs are also provided between the two; the front support gasket and the rear support gasket are close to the shaft shoulder.

3. The electric linear actuator stiffness, precision and performance retention testing device according to claim 1, characterized in that: The connector assembly includes a connector, a lens base connecting tool and a lens base; both ends of the connector are provided with external threads, the external thread at one end is connected to the internal thread at the free end of the actuating rod of the electric linear actuator, the lens base connecting tool is fastened between the actuating rod and the connector, and the external thread at the other end is connected to the internal thread at one end of the S-type tension and pressure sensor; the lens base is fixedly connected to the lens base connecting tool.

4. The electric linear actuator stiffness, precision and performance retention testing device according to claim 1, characterized in that: The support module comprises a platform, a front support seat of the electric linear actuator fixedly mounted on the platform, and a rear support seat of the electric linear actuator; the electric linear actuator to be tested is fixedly mounted on the front and rear support seats of the electric linear actuator.

5. The electric linear actuator stiffness, precision and performance retention testing device 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, S-type tension and pressure sensor and laser interferometer.

6. A method for testing stiffness of an electric linear actuator, characterized in that: The electric linear actuator stiffness, precision and performance retention testing device according to any one of claims 1 to 5 comprises: (1) Starting from the zero position of the electric linear actuator to be tested, set S test points and record the kth test point as Q k ; (2) Synchronously switching the servo electric cylinder and the electric linear actuator to be tested to the zero position of the electric linear actuator to be tested; (3) The load of the electric linear actuator to be tested is increased at a certain interval value to a specified maximum value, and the pressure is maintained at each load value. Each sampled value is recorded, and the laser interferometer reading corresponding to each load value is synchronously collected to obtain a set of data on the corresponding relationship between the load force and deformation of the electric linear actuator; Electric linear actuator loading force: f n =F n -F0; Deformation: δ n =x n -x0; Where: F0 and x0 are the readings of the S-type tension and pressure sensor and the laser interferometer respectively when there is no load; F n is the nth sampling value, x n is the nth reading value, n=1,2,3…,m, m is the number of samples; (4) Unloading the electric linear actuator to be tested, then loading the electric linear actuator in the opposite direction, repeating step (3), and obtaining another set of data on the corresponding relationship between the loading force and the deformation of the electric linear actuator. According to the difference in the directions of the two load applications, the two sets of data are regarded as the test results of the electric linear actuator under tension and compression, respectively; (5) Repeat the independent loading p times in the tension and compression directions to obtain multiple sets of valid data; (6) Use the motion control card to synchronously switch the servo electric cylinder and the electric linear actuator to the next test point, and repeat steps (3), (4), and (5) until valid data for all test points are obtained.

7. A method for testing the accuracy of an electric linear actuator, characterized in that: The electric linear actuator stiffness, precision and performance retention testing device according to any one of claims 1 to 5 comprises: (1) Set the measurement stroke, test speed, target position and reciprocating number N of the electric linear actuator; set the servo electric cylinder to the position passive following mode; set the laser interferometer data collection point position according to the target position; (2) Start and run the electric linear actuator according to the set stroke, test speed, target position and number of reciprocating times; (3) After the electric linear actuator runs N reciprocating cycles according to the set stroke, the actual position reached by the electric linear actuator in the extending direction approaching the target position and the actual position reached by the electric linear actuator in the retracting direction approaching the target position are obtained based on the measurement values ​​of the laser interferometer during these N operating cycles.

8. The electric linear actuator accuracy testing method according to claim 7, characterized in that: Also includes: Calculate the one-way positioning accuracy and repeatability of the electric linear actuator under test in the extension and retraction directions, as well as its two-way positioning accuracy and repeatability: One-way positioning accuracy in the extension direction: One-way positioning accuracy in retracting direction: Bidirectional positioning accuracy: One-way repeat positioning accuracy in the extension direction: R↑=max[R i ↑]; R i ↑=4S i ↑; One-way repeat positioning accuracy in retracting direction: R↓=max[R i ↓]; R i ↓=4S i ↓; Bidirectional repeat positioning accuracy: R = max[R i ]; Where X ij ↑ and X ij ↓represents the positioning deviation of the electric linear actuator when it approaches the i-th target position in the extension and retraction directions for the jth time; and They represent the average positioning deviation when approaching the i-th target position along the extension and retraction directions respectively; S i ↑ and S i ↓ respectively represent the estimated values ​​of repeatability when approaching the i-th target position along the extension and retraction directions; R i ↑ and R i ↓ represents the repeatability accuracy when approaching the i-th target position along the extension and retraction directions; R i represents the bidirectional repeatability of the i-th target position; B i Represents the reverse difference of the i-th target position.

9. A method for testing the stiffness and precision retention of an electric linear actuator, characterized in that: The electric linear actuator stiffness, precision and performance retention testing device according to any one of claims 1 to 5 comprises: (1) Conduct stiffness test, control the electric linear actuator to increase the load to the specified maximum value at a certain interval value, and load the electric linear actuator in the opposite direction to complete the stiffness data collection of the electric linear actuator under tension and compression; conduct accuracy test, control the measurement stroke, test speed, target position and number of reciprocating operations of the electric linear actuator to be tested, control the servo electric cylinder to the position passive following mode, and complete the positioning accuracy data collection; (2) Set the servo electric cylinder to a control mode where force is actively input and position is passively followed; set the running mileage or running time of the electric linear actuator within one operating 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 the S-type tension and pressure sensor to collect the load applied by the servo electric cylinder to achieve real-time monitoring of the running process of the electric linear actuator; (4) After the electric linear actuator has finished running according to the set running mileage or running time, the stiffness test method and the accuracy test method are used 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 carry out the stiffness and accuracy retention test for the next operating cycle until the operating accuracy / stiffness of the electric linear actuator fails or the set cut-off mileage / time is reached.

10. The electric linear actuator stiffness, precision and performance retention testing device according to any one of claims 1 to 5, wherein the installation method comprises: Step 1: Install the support module and the electric linear actuator to be tested: Fix the electric linear actuator to be tested on the support module, and adjust the parallelism of the electric linear actuator to be tested along the feed direction; after installing the electric linear actuator to be tested, run the electric linear actuator back and forth for several times; Step 2: Install the force loading module and the measuring module: ensure that the S-type tension and pressure sensor and the actuator rod of the electric linear actuator to be tested are coaxial and parallel to the movement direction of the servo electric cylinder; install the laser interferometer, fixed optical lens group and mobile reflector, and ensure that the measuring optical path is parallel to the axis of the actuator rod of the electric linear actuator to be tested; Step 3: Eliminate installation gap: After adjusting the position of the electric linear actuator's actuator rod to zero, perform a pre-load to eliminate the installation gap, clear the laser interferometer reading, and record the zero point position information.

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