A suspension system test bench and test method based on road load spectrum

Abstract

The application relates to a suspension system test bench and a test method based on a road load spectrum, which comprises a suspension loading body, a rim connecting tool for connecting the suspension, an actuator connecting tool for connecting a loading actuator fixedly connected to the bottom of the rim connecting tool, a loading actuator, a vertical actuator, a lateral actuator and a longitudinal actuator for respectively applying vertical force, lateral force and longitudinal force to the suspension and connected to the actuator connecting tool, and the directions of the vertical force, the lateral force and the longitudinal force applied by the vertical actuator, the lateral actuator and the longitudinal actuator respectively intersect at a point and the distance between the point and the center point of the rim is equal to the radius of the tire on the rim. The application can simulate the complex stress condition of the suspension system under the actual vehicle state, more truly reproduce the excitation of the suspension system on the actual road surface through the test bench, ensure that the failure mode of the suspension is consistent with the actual failure mode, and truly play the role of testing the suspension system.

Description

Technical Field

[0001] This application relates to the field of passenger vehicle suspension testing technology, and in particular to a suspension system test bench and test method based on road load spectrum. Background Technology

[0002] The automotive suspension is a crucial component that elastically connects the vehicle body and wheels. It typically consists of elastic elements, guiding mechanisms, shock absorbers, and other parts. Its primary function is to mitigate impacts transmitted from uneven road surfaces to the vehicle body, thereby improving ride comfort. It also plays a supporting role in the vehicle body. The performance of the suspension system is of great significance to the vehicle's overall performance. Therefore, to test the lifespan of the suspension system or to continuously optimize its design, it is necessary to test each of its components. This requires the use of bench testing to simulate driving conditions.

[0003] The bench test of the existing automotive suspension system involves the following process: collecting load data of the suspension system, obtaining test drive signals through multiple iterations by software, and then driving the loading actuator according to the drive signals. This enables a multi-channel, road load spectrum loading road simulation bench test of the passenger car suspension system.

[0004] However, the load data acquisition points (strain gauges are used to collect load data, and the load data collected will be different depending on the location of the strain gauges) and the loading points of the loading actuators (the actuators are used to provide loading force to the vehicle, which is equivalent to the point where the excitation from the ground is transmitted to the vehicle body; the location of the loading force will be different depending on the location of the actuators) all affect the test results, resulting in the suspension system test results obtained by this method being inaccurate.

[0005] As can be seen from the bench test process of the existing automotive suspension system, applying loading force to the loading actuator of the test vehicle simulates the process of ground excitation being transmitted to the vehicle body through the loading point. However, ground excitation is not only related to road conditions but also to the vehicle's braking status. For example, the excitation transmission from the ground to the vehicle body is different under the same road conditions during acceleration and deceleration. If the same sampling point is used to collect the load spectrum under all operating conditions, it may not accurately reflect the excitation transmission from the road to the vehicle body under the current road conditions and vehicle braking, which will cause errors in subsequent test processes and affect the accuracy of the test. Summary of the Invention

[0006] This application provides a test bench and test method for a suspension system based on road load spectrum, in order to solve the problem that the bench test of automobile suspension system does not have clear requirements for the installation position of actuators, which leads to inaccurate bench tests.

[0007] This application provides a suspension system test bench based on road load spectrum, including:

[0008] A suspension loading body, the suspension loading body including a rim connecting fixture for connecting the suspension, and an actuator connecting fixture for connecting a loading actuator is fixedly connected to the bottom of the rim connecting fixture;

[0009] A loading actuator, comprising a vertical actuator, a lateral actuator, and a longitudinal actuator connected to an actuator connecting fixture and respectively applying vertical force, lateral force, and longitudinal force to the suspension;

[0010] The vertical, lateral, and longitudinal forces applied by the vertical actuator, lateral actuator, and longitudinal actuator respectively intersect at a point, and the distance between the vertical actuator and the center point of the rim is equal to the radius of the tire on the rim.

[0011] In some embodiments: the rim connecting fixture includes a vertical mounting plate with an isosceles trapezoidal structure, the vertical mounting plate having a plurality of mounting holes for connecting the suspension, the bottom of the vertical mounting plate being connected to a horizontal mounting plate, and the actuator connecting fixture being fixedly connected to the bottom of the horizontal mounting plate.

[0012] In some embodiments: both sides of the vertical mounting plate are provided with triangular reinforcing ribs that are connected to the horizontal mounting plate. The triangular reinforcing ribs are welded to the vertical mounting plate and the horizontal mounting plate respectively. The horizontal mounting plate is provided with mounting holes for connecting the actuator connecting tool.

[0013] In some embodiments, the actuator connecting fixture is a rectangular column structure, and the outer wall of the actuator connecting fixture is provided with threaded holes for connecting the transverse mounting plate, the vertical actuator, the transverse actuator and the longitudinal actuator respectively.

[0014] In some embodiments: the vertical actuator, the lateral actuator, and the longitudinal actuator each include a loading actuator, a force sensor connected to the telescopic arm of the loading actuator, and a universal joint connected to the force sensor, wherein the universal joint is fixedly connected to the actuator connecting fixture.

[0015] In some embodiments, the loading actuator further includes a controller that applies control signals to the vertical actuator, the lateral actuator, and the longitudinal actuator.

[0016] A second aspect of this application provides a suspension system testing method based on road load spectrum, the method comprising:

[0017] Step 1: Obtain the reference road surface excitation signal and the test vehicle with multiple preset acquisition points, and install strain gauges on each preset acquisition point of the test vehicle. Conduct a real vehicle test on the road surface corresponding to the reference road surface excitation signal to obtain the road spectrum data of each preset acquisition point of the test vehicle under the road surface.

[0018] Step 2: Under each group of road surfaces, compare the road spectrum data collected by all preset collection points of the test vehicle with the reference road surface excitation signal, find the road spectrum data whose similarity to the reference road surface excitation signal is less than the first preset threshold, and take the preset collection point corresponding to the road spectrum data as the target collection point corresponding to the group of road surfaces.

[0019] Step 3: Install strain gauges at the target acquisition point of the vehicle under test, and conduct a real vehicle test at the test site to obtain the load spectrum when the road excitation is transmitted to the target acquisition point.

[0020] Step 4: Obtain the transfer function from the actuator loading point to the load spectrum acquisition point using white noise. Obtain the primary test control signal from the load spectrum based on the inverse transfer function of the transfer function. Then, obtain the final test control signal by multiple iterations using RPC software. Input the final test control signal into the suspension system test bench based on road load spectrum as described in any of the above embodiments to conduct the bench test.

[0021] In some embodiments: the reference road surface excitation signal is a continuous road surface excitation signal or a random road surface excitation signal, wherein the continuous road surface excitation signal is a continuous excitation along the road length direction, and the random road surface excitation signal is an intermittent excitation with an impact effect.

[0022] In some embodiments: step 2 specifically includes:

[0023] The data a1 at the next moment of the reference road excitation signal is compared with the data a2 at the previous moment, A1 = (a1-a2) / a2. The data b1 at the next moment of the time domain signal and the data b2 at the previous moment of the time domain signal at all preset acquisition points of the test vehicle are compared with the data b2 at the previous moment, B1 = (b1-b2) / b2. When the absolute value of the difference between A1 and B1 in the time domain signal is less than the first preset threshold, the road spectrum data collected by the preset acquisition point has a high similarity with the reference road excitation signal, and the preset acquisition point is selected as the target acquisition point corresponding to the road surface.

[0024] In some embodiments: the primary test control signal is obtained from the load spectrum based on the inverse transfer function of the transfer function, specifically including:

[0025] The loading signal that should be applied at the actuator loading point is obtained by using the inverse function of the transfer function. The loading signal is then divided into primary test control signals in the longitudinal, lateral, and vertical directions.

[0026] The beneficial effects of the technical solution provided in this application include:

[0027] This application provides a suspension system test bench and test method based on road load spectrum. The test bench includes a suspension loading body, comprising a rim connection fixture for connecting the suspension, and an actuator connection fixture for connecting a loading actuator fixedly connected to the bottom of the rim connection fixture. The loading actuator includes a vertical actuator, a lateral actuator, and a longitudinal actuator connected to the actuator connection fixture and respectively applying vertical, lateral, and longitudinal forces to the suspension. The directions of the vertical, lateral, and longitudinal forces applied by the vertical, lateral, and longitudinal actuators intersect at a point, and the distance from the center point of the rim is equal to the radius of the tire on the rim.

[0028] Therefore, the application ensures that all actuators apply load force from the vehicle's contact point. Applying force at the vehicle's contact point not only simulates the road surface transmitting excitation to the vehicle body (because when a vehicle is moving, there is always only one contact point with the road surface, and the road excitation is transmitted to the vehicle from this contact point), but also simulates the downward pressure load transmitted from above to this contact point. This contact point can better simulate the real vehicle condition. It can more realistically simulate the complex stress conditions of the suspension system under real vehicle conditions, and more realistically reproduce the excitation of the suspension system on the actual road surface through the test bench, ensuring that the suspension failure mode is consistent with the actual failure mode, and truly serving the purpose of testing the suspension system. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the suspension system test bench according to an embodiment of this application;

[0031] Figure 2 This is a flowchart of the suspension system test bench test method according to an embodiment of this application.

[0032] Figure label:

[0033] 10. Suspension loading body; 11. Wheel rim connecting fixture; 12. Actuator connecting fixture; 13. Vertical mounting plate; 14. Lateral mounting plate; 15. Triangular reinforcing rib; 20. Loading actuator; 21. Vertical actuator; 22. Lateral actuator; 23. Longitudinal actuator; 24. Force sensor; 25. Universal joint; 30. Suspension. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] This application provides a test bench and test method for suspension systems based on road load spectrum, which can solve the problem in related technologies where the bench test of automobile suspension systems does not have clear requirements for the installation position of actuators, resulting in inaccurate bench tests.

[0036] See Figure 1 As shown, the first aspect of this application provides a suspension system test bench based on road load spectrum, comprising:

[0037] The suspension loading body 10 includes a rim connecting fixture 11 for connecting the rim of the suspension 30, and an actuator connecting fixture 12 for connecting the loading actuator 20 is fixedly connected to the bottom of the rim connecting fixture 11.

[0038] The loading actuator 20 includes a vertical actuator 21, a lateral actuator 22, and a longitudinal actuator 23, which are connected to the actuator connecting fixture 12 and apply vertical force, lateral force, and longitudinal force to the suspension 30, respectively.

[0039] The vertical actuator 21, the lateral actuator 22, and the longitudinal actuator 23 apply vertical, lateral, and longitudinal forces respectively, which intersect at a point and are spaced from the center point of the rim, equal to the radius of the tire on the rim.

[0040] The point where the vertical, lateral, and longitudinal forces applied by the vertical actuator 21, lateral actuator 22, and longitudinal actuator 23 intersect is the contact point between the tire and the road surface. This is because when the vehicle is in motion, the tire and the road surface always have only one contact point, and the road surface's excitation is transmitted to the vehicle from this contact point.

[0041] The embodiments of this application enable all actuators to apply load force from the vehicle's contact point. Applying force at the vehicle's contact point can not only simulate the road surface transmitting excitation to the vehicle body, but also simulate the downward pressure load transmitted from above to the contact point by the vehicle body. This contact point can better simulate the actual vehicle condition.

[0042] This application can more realistically simulate the complex stress conditions of the suspension system under real vehicle conditions. By using a test bench, it can more realistically reproduce the excitation of the suspension system on the actual road surface, ensuring that the failure mode of the suspension 30 is consistent with the actual failure mode, and truly playing the role of testing the suspension system.

[0043] In some alternative embodiments: Participate Figure 1 As shown in the figure, this application embodiment provides a suspension system test bench based on road load spectrum. The rim connection fixture 11 of the suspension system test bench includes a vertical mounting plate 13 with an isosceles trapezoidal structure. Multiple mounting holes for connecting the rims of the suspension 30 are provided on the vertical mounting plate 13. A transverse mounting plate 14 is connected to the bottom of the vertical mounting plate 13, and an actuator connection fixture 12 is fixedly connected to the bottom of the transverse mounting plate 14.

[0044] Triangular reinforcing ribs 15, which connect to the horizontal mounting plate 14, are provided on both sides of the vertical mounting plate 13. These triangular reinforcing ribs 15 are welded to both the vertical mounting plate 13 and the horizontal mounting plate 14. The horizontal mounting plate 14 has mounting holes for connecting the actuator connecting fixture 12. Four triangular reinforcing ribs 15 are provided, arranged symmetrically in pairs on both sides of the vertical mounting plate 13 to enhance the structural strength of the connection between the vertical mounting plate 13 and the horizontal mounting plate 14.

[0045] In some alternative embodiments: Participate Figure 1 As shown, this application embodiment provides a suspension system test bench based on road load spectrum. The actuator connecting fixture 12 of the suspension system test bench is a rectangular column structure. The outer wall of the actuator connecting fixture 12 is provided with threaded holes for connecting the transverse mounting plate 14, the vertical actuator 21, the transverse actuator 22 and the longitudinal actuator 23 respectively.

[0046] The vertical actuator 21 is located at the top or bottom of the actuator connecting fixture 12, and the vertical actuator 21 is used to drive the actuator connecting fixture 12 to move along the Z-axis direction; the horizontal actuator 22 is located on the left or right side of the actuator connecting fixture 12, and the horizontal actuator 22 is used to drive the actuator connecting fixture 12 to move along the Y-axis direction; the longitudinal actuator 23 is located on the front or rear side of the actuator connecting fixture 12, and the longitudinal actuator 23 is used to drive the actuator connecting fixture 12 to move along the X-axis direction.

[0047] In some alternative embodiments: Participate Figure 1 As shown, this application embodiment provides a suspension system test bench based on road load spectrum. The vertical actuator 21, lateral actuator 22 and longitudinal actuator 23 of the suspension system test bench all include a loading actuator, a force sensor 24 connected to the telescopic arm of the loading actuator, and a universal joint 25 connected to the force sensor 24. The universal joint 25 is fixedly connected to the actuator connecting fixture 12.

[0048] The loading actuator also includes a controller that applies control signals to the vertical actuator 21, the lateral actuator 22, and the longitudinal actuator 23. The controller is used to obtain the load spectrum when the road excitation is transferred to the target acquisition point by the test vehicle in the test field; to obtain the transfer function from the actuator loading point to the load spectrum acquisition point by white noise; to obtain the primary test control signal from the load spectrum according to the inverse transfer function of the transfer function; and to obtain the final test control signal by the RPC software through multiple iterations to control the loading actuator 20 for bench testing.

[0049] A second aspect of this application provides a suspension system testing method based on road load spectrum, the method comprising:

[0050] Step 1: Obtain the reference road surface excitation signal and the test vehicle with multiple preset acquisition points, and install strain gauges on each preset acquisition point of the test vehicle. Conduct a real vehicle test on the road surface corresponding to the reference road surface excitation signal to obtain the road spectrum data of each preset acquisition point of the test vehicle under the road surface.

[0051] Step 2: Under each group of road surfaces, compare the road spectrum data collected by all preset collection points of the test vehicle with the reference road surface excitation signal, find the road spectrum data whose similarity to the reference road surface excitation signal is less than the first preset threshold, and take the preset collection point corresponding to the road spectrum data as the target collection point corresponding to the group of road surfaces.

[0052] Step 3: Install strain gauges at the target acquisition point of the vehicle under test, and conduct a real vehicle test at the test site to obtain the load spectrum when the road excitation is transmitted to the target acquisition point.

[0053] Step 4: Obtain the transfer function from the actuator loading point to the load spectrum acquisition point using white noise. Obtain the primary test control signal from the load spectrum based on the inverse transfer function of the transfer function. Then, obtain the final test control signal by multiple iterations using RPC software. Input the final test control signal into the suspension system test bench based on road load spectrum as described in any of the above embodiments to conduct the bench test.

[0054] In some optional embodiments: This application provides a suspension system testing method based on road load spectrum. The reference road surface excitation signal of this suspension system testing method is a time-domain signal of the road surface excitation to the vehicle. This reference road surface excitation signal can be obtained from measured random data of the highway surface. The reference road surface excitation signal can be a continuous road surface excitation signal or a random road surface excitation signal. The continuous road surface excitation signal is a continuous excitation along the length of the road and can be an asphalt pavement. The random road surface excitation signal is an intermittent excitation with impact effect, which is a discrete event with a short time and has strong intensity, such as potholes, road surface cracks, etc.

[0055] It is important to note that the test vehicle should be tested on the corresponding road surface type to obtain road spectrum data that matches the road surface type. Specifically, the road spectrum data is the time-domain signal displayed on the strain gauges at the preset acquisition points when the test vehicle is driving on the corresponding road surface type.

[0056] In some optional embodiments: This application provides a suspension system testing method based on road load spectrum, wherein step 2 of the suspension system testing method specifically includes:

[0057] By comparing the changing trends of the time-domain signal at each preset acquisition point with the time-domain signal of the reference road surface excitation signal, road spectrum data with high similarity to the reference road surface excitation signal is obtained. The changing trend can be understood as follows: when comparing the data a1 at the next moment and the data a2 at the previous moment of the reference road surface excitation signal, A1 = (a1-a2) / a2; when comparing the data b1 at the next moment and the data b2 at the previous moment of the time-domain signal at all preset acquisition points of the test vehicle, B1 = (b1-b2) / b2; when the absolute value of the difference between A1 and B1 in the time-domain signal is less than the first preset threshold, the road spectrum data collected by the preset acquisition point has high similarity to the reference road surface excitation signal, and the preset acquisition point is selected as the target acquisition point corresponding to the group of road surfaces.

[0058] In some optional embodiments: This application provides a suspension system testing method based on road load spectrum. In this method, a primary test control signal is obtained from the load spectrum according to the inverse transfer function of the transfer function. Specifically, it includes:

[0059] Multiple preset data acquisition points can be randomly set for the test vehicle, or they can be set based on past experience. After setting them, strain gauges are installed at the preset data acquisition points to collect load data on the road surface when the road excitation is transmitted to each preset data acquisition point. The road spectrum data collected at each preset data acquisition point is compared with the reference road excitation signal. The road spectrum data with the most similar trend to the reference road excitation signal is found, and the preset data acquisition point corresponding to the road spectrum data is taken as the target data acquisition point. It is believed that the road spectrum data collected at the target data acquisition point can most realistically and accurately reproduce the road excitation transmitted from the road surface to the vehicle body.

[0060] Specifically, since the target acquisition point that can most realistically reproduce the road surface excitation transmission to the vehicle body was found through the test vehicle, strain gauges can be directly installed at the target acquisition point on the vehicle under test to obtain a load spectrum that realistically reproduces the road surface excitation. Based on this load spectrum, the transfer function from the actuator loading point (vehicle ground contact point) to the load spectrum acquisition point (target acquisition point) is obtained through white noise, and this transfer function is also the most accurate.

[0061] The loading signal that should be applied to the actuator loading point can be obtained by using the inverse function of the transfer function. The loading signal is divided into X-axis, Y-axis, and Z-axis control signals. The RPC software then performs multiple iterations to obtain the final test control signal for each direction. The final test control signal for each direction is input to the actuator in the corresponding direction through the controller to simulate the excitation process of the road surface on the vehicle. In this context, the service life of the suspension system can be predicted by detecting the strength and fatigue of the sub-components of the suspension system.

[0062] Working principle

[0063] This application provides a suspension system test bench and test method based on road load spectrum. The suspension system test bench based on road load spectrum is provided with a suspension loading body 10. The suspension loading body 10 includes a rim connecting fixture 11 for connecting the suspension 30. The bottom of the rim connecting fixture 11 is fixedly connected to an actuator connecting fixture 12 for connecting the loading actuator 20. The loading actuator 20 includes a vertical actuator 21, a lateral actuator 22, and a longitudinal actuator 23 connected to the actuator connecting fixture 12 and respectively applying vertical force, lateral force, and longitudinal force to the suspension 30. The directions of the vertical force, lateral force, and longitudinal force applied by the vertical actuator 21, the lateral actuator 22, and the longitudinal actuator 23 intersect at a point and the distance from the center point of the rim is equal to the radius of the tire on the rim.

[0064] Therefore, the application ensures that all actuators apply load force from the vehicle's contact point. Applying force at the vehicle's contact point not only simulates the road surface transmitting excitation to the vehicle body (because when a vehicle is moving, there is always only one contact point with the road surface, and the road excitation is transmitted to the vehicle from this contact point), but also simulates the downward pressure load transmitted from above to this contact point. This contact point can better simulate the real vehicle condition. It can more realistically simulate the complex stress conditions of the suspension system under real vehicle conditions, and more realistically reproduce the excitation of the suspension system on the actual road surface through the test bench, ensuring that the suspension failure mode is consistent with the actual failure mode, and truly serving the purpose of testing the suspension system.

[0065] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0066] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0067] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A test method for a suspension system based on road load spectrum, characterized in that, The method includes: Step 1: Obtain the reference road surface excitation signal and the test vehicle with multiple preset acquisition points, and install strain gauges on each preset acquisition point of the test vehicle. Conduct a real vehicle test on the road surface corresponding to the reference road surface excitation signal to obtain the road spectrum data of each preset acquisition point of the test vehicle under the road surface. Step 2: Under each group of road surfaces, compare the road spectrum data collected by all preset collection points of the test vehicle with the reference road surface excitation signal, find the road spectrum data whose similarity to the reference road surface excitation signal is less than the first preset threshold, and take the preset collection point corresponding to the road spectrum data as the target collection point corresponding to the group of road surfaces. Step 3: Install strain gauges at the target acquisition point of the vehicle under test, and conduct a real vehicle test at the test site to obtain the load spectrum when the road excitation is transmitted to the target acquisition point. Step 4: Obtain the transfer function from the actuator loading point to the load spectrum acquisition point using white noise. Obtain the primary test control signal from the load spectrum based on the inverse transfer function of the transfer function. Then, obtain the final test control signal by multiple iterations using RPC software. Input the final test control signal into the suspension system test bench based on the road load spectrum to conduct the bench test. The suspension system test bench based on road load spectrum includes: The suspension loading body (10) includes a rim connecting fixture (11) for connecting the suspension (30), and an actuator connecting fixture (12) for connecting the loading actuator (20) is fixedly connected to the bottom of the rim connecting fixture (11). Loading actuator (20), the loading actuator (20) includes a vertical actuator (21), a lateral actuator (22) and a longitudinal actuator (23) connected to the actuator connecting fixture (12) and respectively applying vertical force, lateral force and longitudinal force to the suspension (30). The vertical actuator (21), the lateral actuator (22), and the longitudinal actuator (23) apply vertical, lateral, and longitudinal forces respectively, which intersect at a point and are spaced from the center point of the rim, equal to the radius of the tire on the rim.

2. The suspension system test method based on road load spectrum as described in claim 1, characterized in that: The reference road surface excitation signal is either a continuous road surface excitation signal or a random road surface excitation signal. The continuous road surface excitation signal is a continuous excitation along the length of the road, and the random road surface excitation signal is an intermittent excitation with an impact effect.

3. The suspension system test method based on road load spectrum as described in claim 1, characterized in that, Step 2 specifically includes: The data a1 at the next moment of the reference road excitation signal is compared with the data a2 at the previous moment, A1 = (a1-a2) / a2. The data b1 at the next moment of the time domain signal and the data b2 at the previous moment of the time domain signal at all preset acquisition points of the test vehicle are compared with the data b2 at the previous moment, B1 = (b1-b2) / b2. When the absolute value of the difference between A1 and B1 in the time domain signal is less than the first preset threshold, the road spectrum data collected by the preset acquisition point has a high similarity with the reference road excitation signal, and the preset acquisition point is selected as the target acquisition point corresponding to the road surface.

4. The suspension system test method based on road load spectrum as described in claim 1, characterized in that, The primary test control signal is obtained from the load spectrum based on the inverse transfer function of the transfer function, specifically including: The inverse function of the transfer function yields the load signal that should be applied at the actuator loading point. The load signal is then divided into primary test control signals for longitudinal, lateral, and vertical directions.

5. The suspension system test method based on road load spectrum as described in claim 1, characterized in that: The rim connecting fixture (11) includes a vertical mounting plate (13) with an isosceles trapezoidal structure. The vertical mounting plate (13) has multiple mounting holes for connecting the suspension (30). The bottom of the vertical mounting plate (13) is connected to a horizontal mounting plate (14). The actuator connecting fixture (12) is fixedly connected to the bottom of the horizontal mounting plate (14).

6. The suspension system test method based on road load spectrum as described in claim 5, characterized in that: Both sides of the vertical mounting plate (13) are provided with triangular reinforcing ribs (15) that are connected to the horizontal mounting plate (14). The triangular reinforcing ribs (15) are welded to the vertical mounting plate (13) and the horizontal mounting plate (14) respectively. The horizontal mounting plate (14) is provided with mounting holes for connecting the actuator connecting fixture (12).

7. The suspension system test method based on road load spectrum as described in claim 5, characterized in that: The actuator connecting fixture (12) is a rectangular column structure. The outer wall of the actuator connecting fixture is provided with threaded holes for connecting the horizontal mounting plate (14), the vertical actuator (21), the horizontal actuator (22), and the longitudinal actuator (23).

8. The suspension system test method based on road load spectrum as described in claim 1, characterized in that: The vertical actuator (21), the lateral actuator (22) and the longitudinal actuator (23) each include a loading actuator, a force sensor (24) connected to the telescopic arm of the loading actuator, and a universal joint (25) connected to the force sensor (24). The universal joint (25) is fixedly connected to the actuator connecting fixture (12).

9. The suspension system test method based on road load spectrum as described in claim 1, characterized in that: The loading actuator (20) also includes a controller that applies control signals to the vertical actuator (21), the lateral actuator (22) and the longitudinal actuator (23).

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