Longitudinal modal test method and system for automobile suspension system

Abstract

The embodiment of the invention provides a longitudinal modal test method and system for an automobile suspension system, and the method comprises the steps: reducing the friction force between a vehicle and the ground when the vehicle slides forwards, controlling the vehicle to slide forwards, enabling the front ends of two front wheels of the vehicle to be collided, and enabling the vehicle to rebound after being collided; three-way acceleration time domain signals of a shock absorber spring, an auxiliary frame, a steering knuckle and a swing arm after collision are monitored; and according to all the three-way acceleration time domain signals obtained through monitoring, the suspension movement form under the longitudinal modal frequency of the suspension is determined. According to the method, the suspension movement form under the longitudinal modal frequency of the suspension can be obtained, reference can be provided for longitudinal modal frequency avoiding design of subsequent vehicle parts such as the suspension, a power assembly and an auxiliary frame, and therefore the comfort of an automobile under the working conditions such as a rough road surface is improved.

Description

Technical Field

[0001] This application relates to the technical field of automobiles, and particularly to a method and system for testing the longitudinal mode of an automotive suspension system. Background Art

[0002] Traditional suspension mode identification methods generally include the exciter excitation method and the drop method. Among them, for the exciter excitation method, generally in the vehicle stationary state, the exciter is arranged near the wheel center mounting bolt, and the suspension vibration is excited by the force of the exciter, and the vibration acceleration of the suspension system is extracted for mode identification; for the drop method, generally the vehicle is pushed down from a step about 10 cm high, so that the wheel lands and is subjected to a vertical excitation force to excite the suspension vibration, and the mode of the suspension system is identified by extracting the vibration acceleration. However, the above two methods are generally used to identify the vertical mode of the suspension. For the longitudinal mode, due to factors such as the large longitudinal adhesion between the tire and the ground, it is difficult for the traditional suspension mode identification method to overcome the ground adhesion and excite the longitudinal vibration of the suspension system for longitudinal mode identification.

[0003] The longitudinal mode of the automotive suspension system refers to the first-order mode of the suspension system composed of tires, steering knuckles, spring shock absorbers, etc. in the longitudinal direction of the vehicle. When the vehicle is driving on rough roads, speed bumps and other road surfaces, there are longitudinal forces on the vehicle in the road surface excitation, which easily excite the longitudinal mode of the suspension system. Especially for electric vehicles with flexible subframes, the electric drive suspension system is generally a pure rubber suspension with small damping. Under the longitudinal excitation of the road surface and the suspension system, the subframe and the electric drive system are also prone to cause longitudinal vibrations, resulting in vehicle body driving jitter problems, poor vehicle comfort, and easy to cause user complaints. How to accurately identify the longitudinal mode of the suspension system, and further provide a reference for the longitudinal mode frequency avoidance design of the suspension, powertrain, subframe, etc., and improve the comfort of the vehicle under rough road conditions and other working conditions has become one of the key problems to be solved in current automotive design. Summary of the Invention

[0004] In view of this, this application provides a method and system for testing the longitudinal mode of an automotive suspension system. The aim is to solve or partially solve the problems existing in the background art.

[0005] The first aspect of this application provides a method for testing the longitudinal mode of an automotive suspension system, including the steps of: Reduce the friction between the vehicle and the ground when the vehicle slides forward, control the vehicle to slide forward, so that the front ends of the two front wheels of the vehicle are collided, and the vehicle rebounds after being collided; Monitor the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm after the collision; Determine the suspension motion form at the longitudinal mode frequency of the suspension according to all the monitored three-axis acceleration time-domain signals.

[0006] Optionally, determining the suspension motion form at the longitudinal mode frequency of the suspension based on all the three-axis acceleration time-domain signals obtained through monitoring includes: Extracting the longitudinal acceleration time-domain signal from the three-axis acceleration time-domain signals of the steering knuckle; Determining the modal frequency of the suspension in the longitudinal direction based on the longitudinal acceleration time-domain signal of the steering knuckle after collision; Determining the suspension motion form at the modal frequency based on all the three-axis acceleration time-domain signals obtained through monitoring.

[0007] Optionally, determining the modal frequency of the suspension in the longitudinal direction based on the longitudinal acceleration time-domain signal of the steering knuckle after collision includes: Performing low-pass filtering on the longitudinal acceleration time-domain signal of the steering knuckle; Extracting the times corresponding to the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle after low-pass filtering; Determining the average duration between the second and fourth acceleration peaks based on the extracted times; Taking the reciprocal of the average duration to obtain the modal frequency of the suspension in the longitudinal direction.

[0008] Optionally, determining the suspension motion form at the modal frequency based on all the three-axis acceleration time-domain signals obtained through monitoring includes: Performing working deformation analysis on all the three-axis acceleration time-domain signals obtained through monitoring to obtain the motion forms of the vehicle body and the suspension at the modal frequency; Based on the motion forms of the vehicle body and the suspension at the modal frequency, setting the vehicle body as the reference system and determining the motion form of the suspension relative to the vehicle body; Determining the motion form of the suspension relative to the vehicle body as the suspension motion form at the modal frequency.

[0009] Optionally, before determining the suspension motion form at the longitudinal mode frequency of the suspension based on all the three-axis acceleration time-domain signals obtained through monitoring, the steps further include: Selecting a target three-axis acceleration time-domain signal from the three-axis acceleration time-domain signals of the shock absorber spring and the subframe; Performing modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle; In the case of passing the modal dominance verification, determining that all the three-axis acceleration time-domain signals can be used to determine the suspension motion form at the modal frequency; In the case of not passing the modal dominance verification, re-executing the longitudinal mode test to determine new three-axis acceleration time-domain signals.

[0010] Optionally, perform modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle, including: Use the time period between the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle as the verification time period; Determine the maximum acceleration of the steering knuckle within the verification time period according to the three-axis acceleration time-domain signal of the steering knuckle; Determine the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal within the verification time period according to the target three-axis acceleration time-domain signal; Compare the maximum acceleration of the steering knuckle with the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal to obtain a corresponding comparison result; Determine whether the modal dominance verification passes according to the comparison result.

[0011] Optionally, the method further includes the steps of: Detect the impact force signals received by the two front wheels during a collision; The step of determining the suspension motion form at the suspension longitudinal modal frequency according to each monitored three-axis acceleration time-domain signal includes: Determine the modal frequency of the suspension in the longitudinal direction and the suspension motion form at the modal frequency according to the impact force signal and each monitored three-axis acceleration time-domain signal.

[0012] A second aspect of the present application provides a longitudinal modal test system for an automotive suspension system, including: A sliding unit for fixing the wheels of the vehicle, reducing the friction between the vehicle and the ground when the vehicle slides forward, controlling the vehicle to slide forward, and causing the vehicle to rebound after being collided; A collision unit for causing the front ends of the two front wheels of the vehicle to be collided; An acceleration monitoring unit including a plurality of three-axis vibration acceleration sensors, and the plurality of three-axis vibration acceleration sensors are respectively used to monitor the three-axis acceleration time-domain signals of the shock absorber spring, the subframe, the steering knuckle, and the swing arm after the collision; A control unit for determining the suspension motion form at the suspension longitudinal modal frequency according to the three-axis acceleration time-domain signals of the shock absorber spring, the subframe, the steering knuckle, and the swing arm after the collision.

[0013] Optionally, the sliding unit includes four sliding carts, and the four sliding carts are used to respectively fix the four wheels of the vehicle, reduce the friction between the vehicle and the ground when the vehicle slides forward, control the vehicle to slide forward, and cause the vehicle to rebound after being collided; The collision unit is arranged in front of the four sliding trolleys. The collision unit includes a bumper and a rigid wall. The bumper is fixed to the side of the rigid wall facing the vehicle, and the bumper is used to simultaneously collide with the front ends of the two front wheels of the vehicle.

[0014] Optionally, the collision unit further includes a force sensor disposed between the bumper and the rigid wall. The force sensor is used to detect the impact force signals received by the two front wheels during the collision. The force sensor and all the triaxial vibration acceleration sensors are respectively connected to the control unit in a signal manner.

[0015] The longitudinal mode test method and system for an automotive suspension system provided by this application have the following advantages: The longitudinal mode test method and system for an automotive suspension system provided by the embodiments of this application enable the vehicle to slide forward and make the front ends of the two front wheels of the vehicle contact an obstacle and be collided during the forward sliding, thereby exciting the longitudinal vibration of the automotive suspension system. By setting a sliding device or lubricating oil between the vehicle and the ground, etc., the friction between the vehicle and the ground during the forward sliding of the vehicle is reduced, thereby reducing the hindrance of the ground adhesion force to the longitudinal vibration of the suspension system. Thus, the longitudinal vibration of the suspension system can be excited to perform longitudinal mode identification. Furthermore, by monitoring the triaxial acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after the collision, the motion states of the relevant components of the suspension system at different times after the collision can be obtained, and finally the suspension motion form at the longitudinal mode frequency of the suspension can be obtained. By obtaining the suspension motion form at the longitudinal mode frequency of the suspension, it can provide a reference for the subsequent longitudinal mode frequency avoidance design of vehicle components such as the suspension, powertrain, and subframe, thereby improving the comfort of the vehicle under working conditions such as rough roads. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a flowchart of a longitudinal mode test method for an automotive suspension system shown in an embodiment of this application; Figure 2 It is a schematic cooperation diagram between an acceleration monitoring unit and a control unit in a longitudinal mode test system for an automotive suspension system shown in an embodiment of this application; Figure 3A schematic diagram of the cooperation among a vehicle, a sliding unit, and a collision unit in a longitudinal mode test system for an automotive suspension system according to an embodiment of the present application; Figure 4 Another schematic diagram of the cooperation between an acceleration monitoring unit and a control unit in a longitudinal mode test system for an automotive suspension system according to an embodiment of the present application; Figure 5 Another schematic diagram of the cooperation among a vehicle, a sliding unit, and a collision unit in a longitudinal mode test system for an automotive suspension system according to an embodiment of the present application.

[0018] Description of reference numerals: 1 - Vehicle, 11 - Shock absorber spring, 12 - Subframe, 13 - Steering knuckle, 14 - Swing arm, 21 - Sliding trolley, 22 - Fixed rope, 31 - Impact block, 32 - Rigid wall, 33 - Force sensor, 41 - Data acquisition module, 42 - Acquisition computer. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0020] Referring to Figure 1 , Figure 1 which shows a method for testing the longitudinal (front - rear direction) mode of an automotive suspension system, including the steps of: S1. Reduce the friction between the vehicle and the ground, control the vehicle to slide forward so that the front ends of the two front wheels of the vehicle are collided, and the vehicle rebounds after being collided; In this embodiment, the vehicle can be made to coast forward, and when the vehicle is coasting forward, the front ends of the two front wheels come into contact with an obstacle and are impacted, thereby exciting the longitudinal vibration of the vehicle suspension system. On this basis, the friction between the vehicle and the ground during forward coasting of the vehicle can be reduced by setting a sliding device or lubricating oil between the vehicle and the ground, etc., thereby reducing the hindrance of the ground adhesion force to the longitudinal vibration of the suspension system. Thus, the longitudinal vibration of the suspension system can be excited to perform longitudinal modal identification on the suspension system. Among them, the result of the longitudinal modal identification of the suspension system is to obtain the suspension motion form at the longitudinal modal frequency of the suspension; at the same time, by reducing the friction between the vehicle and the ground during forward coasting of the vehicle, the vehicle can also naturally rebound and move away from the obstacle under the action of the impact force after being impacted, thereby also being able to avoid the situation where the suspension system collides with the obstacle again during the longitudinal vibration process, and the longitudinal vibration of the suspension system is interfered by the obstacle, improving the accuracy of the longitudinal modal identification of the suspension system.

[0021] S2. Monitor the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after the collision; In this embodiment, the three-axis acceleration time-domain signal refers to the continuous data record of the acceleration values measured synchronously in three orthogonal directions (longitudinal, transverse, and vertical) changing with time. Its manifestation form is the continuous waveform data with the three orthogonal directions taking time as the horizontal axis and the acceleration value as the vertical axis, reflecting the change law of the acceleration with time. In an automobile, the shock absorber spring, subframe, steering knuckle, and swing arm are all components related to the suspension system. By monitoring the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after the collision, the motion states of the components related to the suspension system at different times after the collision can be obtained, and thus data support can be provided for determining the suspension motion form at the longitudinal modal frequency of the suspension.

[0022] Next, the steering knuckle and swing arm are arranged in the suspension as movable components of the suspension. By obtaining the three-axis vibration accelerations of the steering knuckle and swing arm, the three-axis acceleration time-domain signal including the change forms of the movable components of the suspension during vibration can be obtained, and finally the suspension motion form at the modal frequency can reflect the modal changes of each component of the suspension itself at the modal frequency; Next, the shock absorber spring and subframe are connected between the vehicle body and the suspension. By obtaining the three-axis vibration accelerations of the shock absorber spring and subframe, the three-axis acceleration time-domain signal including the change form of the relative position between the whole suspension and the vehicle body during vibration can be obtained, and finally the suspension motion form at the modal frequency can reflect the relative modal changes between the suspension and the vehicle body at the modal frequency; Next, since the suspension motion form at the modal frequency can reflect the modal changes of each component of the suspension itself and the relative modal changes between the suspension and the vehicle body at the modal frequency, it is possible to optimize the structure of the suspension itself and the connection structure between the suspension and the vehicle body when providing a reference for the subsequent longitudinal modal frequency avoidance design of vehicle components based on the suspension motion form at the modal frequency, thereby improving the comprehensiveness of the suspension optimization.

[0023] Optionally, the sampling frequency of the three-axis acceleration time-domain signal is 1024 Hz or less, and the frequency resolution is 0.25 Hz.

[0024] S3. Determine the suspension motion form at the longitudinal modal frequency of the suspension based on all the three-axis acceleration time-domain signals obtained by monitoring.

[0025] In this embodiment, all the three-axis acceleration time-domain signals refer to all the three-axis acceleration time-domain signals including those of the shock absorber spring, subframe, steering knuckle, and swing arm. By processing the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after a collision, the longitudinal modal frequency of the suspension and the suspension motion form at this modal frequency (i.e., the vibration mode corresponding to the modal frequency of the suspension) can be determined. By obtaining the suspension motion form at the longitudinal modal frequency of the suspension, the modal changes of the suspension under longitudinal forces can be obtained, providing a reference for the subsequent longitudinal modal frequency avoidance design of vehicle components such as the suspension, powertrain, and subframe, thereby improving the comfort of the vehicle under conditions such as rough roads.

[0026] Combined with the above embodiments, in one implementation, this embodiment provides a method for testing the longitudinal mode of an automotive suspension system. The step of determining the suspension motion form at the longitudinal modal frequency of the suspension based on all the three-axis acceleration time-domain signals obtained by monitoring includes: S31. Extract the longitudinal acceleration time-domain signal from the three-axis acceleration time-domain signal of the steering knuckle. S32. Determine the longitudinal modal frequency of the suspension based on the longitudinal acceleration time-domain signal of the steering knuckle after a collision. S33. Determine the suspension motion form at the modal frequency based on all the three-axis acceleration time-domain signals obtained by monitoring.

[0027] In this embodiment, based on the longitudinal acceleration time-domain signal of the steering knuckle after a collision, the modal frequency in the longitudinal direction of the steering knuckle can be determined. Since the steering knuckle is part of the suspension system, the modal frequency in the longitudinal direction of the steering knuckle can match the modal frequency of the entire suspension in the longitudinal direction. Therefore, the modal frequency in the longitudinal direction of the steering knuckle can be regarded as the modal frequency of the entire suspension in the longitudinal direction. Based on the modal frequency of the entire suspension in the longitudinal direction and the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after the collision, the motion state of the suspension at the modal frequency can be determined. This method does not require obtaining the impact force when the vehicle is collided, and can obtain the required modal frequency and the motion state of the suspension at the modal frequency with fewer parameters, reducing the related costs.

[0028] Among them, the longitudinal acceleration time-domain signal of the steering knuckle is the parameter that can best reflect the longitudinal acceleration of the suspension and can be directly used as the parameter of the longitudinal acceleration of the suspension. Among them, the longitudinal acceleration time-domain signal of the swing arm can also be used to obtain the modal frequency of the suspension in the longitudinal direction, but the error is relatively large. It is preferably to use the longitudinal acceleration time-domain signal of the swing arm as a reference for the longitudinal acceleration of the suspension.

[0029] Combined with the above embodiments, in one implementation, this embodiment provides a method for testing the longitudinal mode of an automotive suspension system. The method for determining the modal frequency of the suspension in the longitudinal direction according to the longitudinal acceleration time-domain signal of the steering knuckle after a collision includes: S321. Perform low-pass filtering on the longitudinal acceleration time-domain signal of the steering knuckle; S322. Extract the times corresponding to multiple acceleration peaks in the longitudinal acceleration time-domain signal of the steering knuckle after low-pass filtering, determine the average duration between the multiple acceleration peaks, and determine the modal frequency of the suspension in the longitudinal direction based on taking the reciprocal of the average duration.

[0030] In this embodiment, low-pass filtering is performed on the longitudinal acceleration time-domain signal of the steering knuckle after the collision to eliminate high-frequency noise during the monitoring process, thereby improving the recognition accuracy of acceleration peaks, and further more accurately improving the accuracy of obtaining the modal frequency. After determining the positions of multiple acceleration peaks in the longitudinal acceleration time-domain signal of the steering knuckle, extract the times corresponding to the multiple acceleration peaks to obtain the average duration between adjacent acceleration peaks in the longitudinal acceleration time-domain signal of the steering knuckle, and thereby determine the modal frequency of the suspension in the longitudinal direction.

[0031] Among them, it is possible to perform 50Hz low-pass filtering on the longitudinal acceleration time-domain signal of the steering knuckle after the collision.

[0032] Combined with the above embodiments, in one implementation manner, this embodiment provides a method for testing the longitudinal mode of an automotive suspension system. The method includes extracting the time corresponding to multiple acceleration peaks of the longitudinal acceleration time-domain signal of the knuckle after low-pass filtering, determining the average duration between multiple acceleration peaks, and taking the reciprocal of the average duration to determine the modal frequency of the suspension longitudinal direction, and the steps include: S3221. Extract the time corresponding to the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the knuckle after low-pass filtering; S3222. Determine the average duration between the second and fourth acceleration peaks according to the extracted time; S3223. Take the reciprocal of the average duration to obtain the modal frequency of the suspension longitudinal direction.

[0033] In this embodiment, the acceleration peak generated when the two front wheels of the vehicle are collided is used as the first acceleration peak. By extracting the time corresponding to the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the knuckle, the time difference between the fourth acceleration peak and the second acceleration peak of the longitudinal acceleration time-domain signal of the knuckle is obtained by subtracting the time corresponding to the second acceleration peak from the time corresponding to the fourth acceleration peak, and the time difference is divided by 2 to obtain the average duration between the second and fourth acceleration peaks, and the reciprocal of the average duration is used as the modal frequency of the suspension longitudinal direction. By obtaining the average duration based on the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the knuckle, the accuracy of the modal frequency can be improved.

[0034] Next, specifically, the first vibration acceleration peak is the acceleration generated when the vehicle is collided under the action of an external force. With the participation of an external force, it does not belong to the mode of the suspension in the free state, and it is difficult to obtain the modal frequency of the suspension longitudinal direction based on the first vibration acceleration peak; the vibration acceleration mode after the fourth vibration acceleration will be greatly attenuated and is not easy to identify; the third vibration acceleration can participate in the calculation of the average duration, but the time intervals corresponding to the third, second, and fourth acceleration peaks are relatively close and are not easy to extract, and due to the short interval time, the deviation of the obtained average duration may be large. Therefore, it is preferred to extract the time corresponding to the second and fourth vibration acceleration peaks.

[0035] Combined with the above embodiments, in one implementation manner, this embodiment provides a method for testing the longitudinal mode of an automotive suspension system. The method for determining the motion form of the suspension at the modal frequency according to all three-axis acceleration time-domain signals obtained by monitoring includes: S331. Perform working deformation analysis on all three-axis acceleration time-domain signals obtained by monitoring to obtain the motion forms of the vehicle body and the suspension at the modal frequency; S332. Based on the motion patterns of the vehicle body and the suspension at the modal frequency, set the vehicle body as the reference system and determine the motion pattern of the suspension relative to the vehicle body; S333. Determine the motion pattern of the suspension relative to the vehicle body as the suspension motion pattern at the modal frequency.

[0036] In this embodiment, by inputting the modal frequency and the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle, and swing arm after the collision into the corresponding program for operational deflection shape analysis, the motion patterns of the vehicle body and the suspension at the modal frequency can be quickly obtained. By setting the vehicle body as the reference system, the vehicle body remains stationary visually in the motion patterns of the vehicle body and the suspension at the modal frequency. At this time, the motion pattern of the suspension relative to the vehicle body is used as the suspension motion pattern at the modal frequency, which can eliminate the influence of the vehicle body motion on the recognition of the suspension motion pattern and reduce the difficulty of recognizing the suspension motion pattern at the modal frequency.

[0037] Among them, since the shock absorber spring and the subframe are connected to the vehicle body, the upper mounting point of the shock absorber spring and the subframe are relatively stationary with respect to the vehicle body. Therefore, the measurement points of the shock absorber spring and / or the subframe (i.e., the points where the three-axis vibration acceleration sensors are installed) can be used as the reference points of the vehicle body.

[0038] Among them, the operational deflection shape analysis can be the ODS operational deflection shape analysis function provided by the data acquisition and analysis system (Simcenter Testlab), which can extract the amplitude and phase information at the target frequency through the Fourier transform (FFT) of the acceleration signals of each measurement point and construct a three-dimensional motion animation. It can be understood that other software or programs capable of performing operational deflection shape analysis can also be applied to this embodiment.

[0039] Combined with the above embodiments, in one implementation manner, this embodiment provides a method for longitudinal modal testing of an automotive suspension system. When the front ends of the two front wheels of the vehicle are collided, it further includes the steps: Detect the impact force signals received by the two front wheels during the collision; The determining the motion pattern of the suspension at the longitudinal modal frequency of the suspension according to each three-axis acceleration time-domain signal obtained by monitoring includes: According to the impact force signal and each of the three-axis acceleration time-domain signals obtained by monitoring, determine the modal frequency of the longitudinal direction of the suspension and the motion pattern of the suspension at the modal frequency through modal analysis methods.

[0040] In this embodiment, when the front ends of the two front wheels of the vehicle are hit, the longitudinal impact force between the front wheels and the obstacle is collected. The impact force can be regarded as an excitation force on the automobile suspension, so that the longitudinal modal frequency of the suspension and the suspension motion form under the modal frequency can be determined simply and quickly based on the excitation force on the automobile suspension and the three-dimensional acceleration time domain signals of each active part of the automobile suspension, thereby improving the efficiency of the longitudinal modal test.

[0041] Among them, the modal analysis method refers to a method of determining the longitudinal modal frequency of the suspension and the suspension motion form at the modal frequency based on the excitation force applied to the automobile suspension and the three-dimensional acceleration time domain signals of the active parts of the automobile suspension. For example, the force signal and the three-dimensional acceleration time domain signals of the active parts of the automobile suspension are directly input into the data acquisition and analysis system (Simcenter Testlab), and the longitudinal modal frequency of the suspension and the suspension motion form at the modal frequency are directly obtained through the frequency response analysis and modal parameter identification algorithm of the data acquisition and analysis system.

[0042] Among them, for the determination of the longitudinal modal frequency of the suspension and the suspension motion form under the modal frequency by the control unit based on the three-dimensional acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm after the collision, there are two methods. The first is to obtain the impact force during the collision, and determine the longitudinal modal frequency of the suspension and the suspension motion form under the modal frequency based on the impact force and the three-dimensional acceleration time-domain signals of each component. The second is to determine the longitudinal modal frequency of the suspension according to the longitudinal acceleration time-domain signal of the steering knuckle after the collision, and determine the suspension motion form under the modal frequency based on the three-dimensional acceleration time-domain signals of each component. In actual testing, only one of the methods can be used to determine the longitudinal modal frequency of the suspension and the suspension motion form under the modal frequency, or both methods can be used to separately determine the longitudinal modal frequency of the suspension and the suspension motion form under the modal frequency, and then the longitudinal modal frequencies of the suspension and the suspension motion forms under the modal frequencies determined by the two methods can be compared and verified to improve the accuracy of the determined longitudinal modal frequencies of the suspension and the suspension motion forms under the modal frequencies.

[0043] In combination with the above embodiments, in one implementation, this embodiment provides a method for testing the longitudinal modal of an automobile suspension system, which further includes the following steps before determining the suspension motion form at the longitudinal modal frequency of the suspension according to all three-axis acceleration time domain signals obtained through monitoring: S21, selecting a target three-dimensional acceleration time domain signal from the three-dimensional acceleration time domain signals of the shock absorber spring and the subframe; S22, performing modal dominance verification on the target three-dimensional acceleration time domain signal and the three-dimensional acceleration time domain signal of the steering knuckle; S23. When the modal dominance verification is passed, determine that all three-axis acceleration time-domain signals can be used to determine the suspension motion pattern at the modal frequency; when the modal dominance verification fails, re-perform the longitudinal modal test to determine a new three-axis acceleration time-domain signal.

[0044] In this embodiment, considering that if the body movement amplitude is too large, it is considered that the suspension mode is dominated by the overall body movement. In this case, the accuracy of the obtained suspension motion pattern is low and cannot meet the design reference requirements. Therefore, the case of too large body movement amplitude needs to be excluded. Based on this, modal dominance verification is performed according to the three-axis acceleration time-domain signals of the steering knuckle, shock absorber spring or subframe. Among them, one of the three-axis acceleration time-domain signals of the shock absorber spring and the subframe can reflect the body movement amplitude. For the convenience of description, this three-axis acceleration time-domain signal is defined as the target three-axis acceleration time-domain signal, and the three-axis acceleration time-domain signal of the steering knuckle can reflect the suspension movement amplitude. The target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle are processed through modal dominance verification: when the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle pass the modal dominance verification, it is considered that the body movement amplitude does not reach an excessive level and the suspension mode is dominated by itself. Therefore, the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm can be applied to the subsequent determination of the suspension motion pattern at the modal frequency; when the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle do not pass the modal dominance verification, it is considered that the body movement amplitude is too large and the suspension mode is dominated by the body. Therefore, the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm cannot be applied to the determination of the suspension motion pattern at the modal frequency. Re-perform the longitudinal modal test to determine a new three-axis acceleration time-domain signal, that is, re-control the vehicle to slide forward so that the front ends of the two front wheels of the vehicle are collided, and obtain the new three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm until the three-axis acceleration time-domain signal of the steering knuckle, shock absorber spring or subframe passes the modal dominance verification.

[0045] Combined with the above embodiments, in one implementation manner, this embodiment provides a method for longitudinal modal testing of an automotive suspension system, and performs modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle, including: S221. Take the time period between the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle as the verification time period; S222. Determine the maximum acceleration of the steering knuckle within the verification time period according to the three-axis acceleration time-domain signal of the steering knuckle; S223. Determine the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal within the verification time period based on the target three-axis acceleration time-domain signal; S224. Compare the maximum acceleration of the steering knuckle with the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal to obtain the corresponding comparison result; S225. Determine whether the modal dominance verification passes according to the comparison result.

[0046] In this embodiment, the method for modal dominance verification is specifically described. The time span for modal dominance verification is determined within the time period between the second and fourth acceleration peaks. This time period is determined as the acquisition period of the modal frequency in the longitudinal direction of the suspension in the above embodiment. The data during this period can match the suspension motion form at the modal frequency. Determine the maximum acceleration of the steering knuckle and the component corresponding to the target three-axis acceleration time-domain signal (hereinafter simply referred to as the target component) within the verification time period based on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle, and perform corresponding comparisons on the maximum accelerations of the steering knuckle and the target component within the verification time period, which can quantitatively judge whether the body motion amplitude is too large and ensure the accuracy of the suspension motion form at the obtained modal frequency.

[0047] Among them, the comparison of the maximum acceleration of the steering knuckle with the maximum acceleration of the target component can be to compare the value obtained by multiplying the maximum acceleration of the target component by a preset magnification factor with the value of the maximum acceleration of the steering knuckle. At this time, determining whether the modal dominance verification passes according to the comparison result can be that when the value of the maximum acceleration of the steering knuckle is greater than or equal to the value obtained by multiplying the maximum acceleration of the target component by the preset magnification factor, it is determined that the modal dominance verification passes; when the value of the maximum acceleration of the steering knuckle is less than the value obtained by multiplying the maximum acceleration of the target component by the preset magnification factor, it is determined that the modal dominance verification fails.

[0048] Among them, the preset magnification factor can be between 1 and 3 times, and more preferably 2 times.

[0049] Based on the same inventive concept, as Figures 2-5 shown, an embodiment of the present application provides a longitudinal modal test system for an automotive suspension system, including: A sliding unit for fixing the wheels of vehicle 1, reducing the friction between vehicle 1 and the ground, controlling vehicle 1 to slide forward, and causing vehicle 1 to rebound after being collided; A collision unit for causing the front ends of the two front wheels of vehicle 1 to be collided; The acceleration monitoring unit includes a plurality of three - axis vibration acceleration sensors, and the plurality of three - axis vibration acceleration sensors are respectively used to monitor the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after a collision. The control unit is used to determine the suspension motion form at the suspension longitudinal modal frequency according to the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after a collision.

[0050] In this embodiment, a longitudinal modal test system is used to perform a longitudinal modal test on the suspension system of vehicle 1. Wherein, vehicle 1 includes a body and a suspension. The body is connected to the suspension through a shock absorber spring 11 and a sub - frame 12. The suspension is provided with a movable steering knuckle 13 and a swing arm 14.

[0051] As Figure 3 shown, before performing the longitudinal modal test, the four wheels of vehicle 1 are placed on the sliding unit. A plurality of three - axis vibration acceleration sensors of the acceleration monitoring unit are respectively arranged on the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 of vehicle 1. The plurality of three - axis vibration acceleration sensors are all signal - connected to the control unit, and the collision unit is arranged directly in front of the two front wheels of vehicle 1. When performing the longitudinal modal test, an external force is applied to vehicle 1 and the sliding unit to make the sliding unit drive vehicle 1 to slide forward, so as to control the front ends of the two front wheels of vehicle 1 to collide with the collision unit. At this time, vehicle 1 can rebound after the collision, and vehicle 1 after rebounding can vibrate freely; As Figure 2 shown, the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after the collision are detected by each three - axis vibration acceleration sensor of the acceleration detection unit; The control unit obtains the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after the collision, and determines the suspension motion form at the modal frequency based on the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after the collision. By obtaining the suspension motion form at the suspension longitudinal modal frequency, it can provide a reference for the subsequent longitudinal modal anti - frequency design of vehicle 1 components such as the suspension, the powertrain, and the sub - frame 12, thereby improving the comfort of the vehicle under working conditions such as rough roads.

[0052] Among them, the plurality of three - axis vibration acceleration sensors are respectively used to monitor the three - axis acceleration time - domain signals of the shock absorber spring 11, the sub - frame 12, the steering knuckle 13, and the swing arm 14 after the collision. At this time, each three - axis vibration acceleration sensor is respectively arranged on the corresponding component to be monitored. For example, one of the three - axis vibration acceleration sensors is arranged on the shock absorber spring 11 to monitor the three - axis acceleration time - domain signal of the shock absorber spring 11 after the collision.

[0053] Among them, the three-axis vibration acceleration sensor arranged on the shock absorber spring 11 is preferably set at the upper mounting point of the shock absorber spring 11, which is usually located on the vehicle body structure (such as inside the wheel arch), and is a key stress point of the suspension system. Ensuring its stability is crucial for driving safety and comfort.

[0054] Among them, the control unit may include a data acquisition module 41 and an acquisition computer 42. The data acquisition module 41 is respectively connected to a plurality of three-axis vibration acceleration sensors through signal lines, and is used to acquire the three-axis acceleration time-domain signals of each three-axis vibration acceleration sensor. The acquisition computer 42 is connected to the data acquisition module 41 through a network cable, and is used to obtain the suspension motion form under the longitudinal modal frequency of the suspension based on the three-axis acceleration time-domain signals of each three-axis vibration acceleration sensor.

[0055] Combined with the above embodiments, in one implementation manner, this embodiment provides a longitudinal modal test system for an automotive suspension system. Among them, the control unit includes: An acceleration extraction unit, configured to extract the longitudinal acceleration time-domain signal from the three-axis acceleration time-domain signal of the steering knuckle; A modal frequency determination unit, configured to determine the longitudinal modal frequency of the suspension according to the longitudinal acceleration time-domain signal of the steering knuckle after a collision; A modal determination unit, configured to determine the suspension motion form under the modal frequency according to all the three-axis acceleration time-domain signals obtained by monitoring.

[0056] Combined with the above embodiments, in one implementation manner, this embodiment provides a longitudinal modal test system for an automotive suspension system. Among them, the modal frequency determination unit includes: A filtering unit, configured to perform low-pass filtering on the longitudinal acceleration time-domain signal of the steering knuckle; A time extraction unit, configured to extract the time corresponding to the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle after low-pass filtering; A first calculation unit, configured to determine the average duration between the second and fourth acceleration peaks according to the extracted time; A second calculation unit, configured to take the reciprocal of the average duration to obtain the longitudinal modal frequency of the suspension.

[0057] Combined with the above embodiments, in one implementation manner, this embodiment provides a longitudinal modal test system for an automotive suspension system. Among them, the modal determination unit includes: A working deformation analysis unit, configured to perform working deformation analysis on all the three-axis acceleration time-domain signals obtained by monitoring, and obtain the motion forms of the vehicle body and the suspension under the modal frequency; A reference system confirmation unit, configured to set the vehicle body as the reference system based on the motion patterns of the vehicle body and the suspension at the modal frequency, and determine the motion pattern of the suspension relative to the vehicle body; A suspension motion determination unit, configured to determine the motion pattern of the suspension relative to the vehicle body as the suspension motion pattern at the modal frequency.

[0058] Combined with the above embodiments, in one implementation, this embodiment provides a longitudinal modal test system for an automotive suspension system, wherein the system further includes: A target signal selection unit, configured to select a target three-axis acceleration time-domain signal from the three-axis acceleration time-domain signals of the shock absorber spring and the subframe; A modal dominance verification unit, configured to perform modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle; A verification passed unit, configured to determine that all three-axis acceleration time-domain signals can be used to determine the suspension motion pattern at the modal frequency when the modal dominance verification is passed; A verification failed unit, configured to re-perform the longitudinal modal test to determine a new three-axis acceleration time-domain signal when the modal dominance verification fails.

[0059] Combined with the above embodiments, in one implementation, this embodiment provides a longitudinal modal test system for an automotive suspension system, wherein the modal dominance verification unit includes: A calibration time period selection unit, configured to use the time period between the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle as the calibration time period; A first maximum acceleration determination unit, configured to determine the maximum acceleration of the steering knuckle within the calibration time period according to the three-axis acceleration time-domain signal of the steering knuckle; A second maximum acceleration determination unit, configured to determine the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal within the calibration time period according to the target three-axis acceleration time-domain signal; A comparison unit, configured to compare the maximum acceleration of the steering knuckle and the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal to obtain a corresponding comparison result; A verification judgment unit, configured to determine whether the modal dominance verification passes according to the comparison result.

[0060] Combined with the above embodiments, in one implementation, this embodiment provides a longitudinal modal test system for an automotive suspension system, wherein the system further includes: An impact force detection unit, configured to detect the impact force signals received by two front wheels during a collision.

[0061] The modal determination unit further includes: A modal determination subunit, configured to determine the modal frequency in the longitudinal direction of the suspension and the suspension motion state at the modal frequency according to the impact force signal and each of the three-axis acceleration time-domain signals obtained by monitoring.

[0062] Combined with the above embodiments, in one implementation manner, this embodiment provides a longitudinal modal test system for an automotive suspension system. The sliding unit includes four sliding trolleys 21, and the four sliding trolleys 21 are respectively used to fix the four wheels of the vehicle 1, reduce the friction between the vehicle 1 and the ground when sliding forward, control the vehicle 1 to slide forward, and cause the vehicle 1 to rebound after being collided. In this embodiment, the four wheels of the vehicle 1 are respectively placed on the four sliding trolleys 21 and fixed by the corresponding sliding trolleys 21. By arranging the sliding trolleys 21, the friction force when the vehicle 1 slides forward is reduced, the attenuation of the free vibration of the vehicle 1 caused by the friction force is reduced, and the accuracy of the suspension motion state at the longitudinal modal frequency of the suspension obtained is improved.

[0063] Next, the four sliding trolleys 21 are respectively used to place the four wheels, so that each wheel operates relatively independently, avoiding mutual interference between the suspension motion states of different wheels during four-wheel linkage, thereby improving the accuracy of the suspension motion state at the longitudinal modal frequency of the suspension obtained.

[0064] Next, by fixing the four wheels respectively by the four sliding trolleys 21, the interference of the rotational inertia of the wheels on the natural frequency of the suspension can be excluded, thereby improving the accuracy of the suspension motion state at the longitudinal modal frequency of the suspension obtained.

[0065] Among them, the sliding trolley 21 can be fixedly connected to the wheel of the vehicle 1 through a fixing rope 22.

[0066] Among them, the weight of the sliding trolley 21 is less than 1 / 8 of the weight of the suspension where the corresponding wheel is located. By making the weight of the sliding trolley 21 less than 1 / 8 of the weight of the suspension where the wheel is located, the influence of the self-mass of the sliding trolley 21 on the vibration of the vehicle 1 suspension is reduced. For example, if the mass of the trolley is too large, it may cause an increase in the equivalent mass of the suspension, resulting in a decrease in the modal frequency and causing a test deviation. Thereby, the accuracy of the suspension motion state at the longitudinal modal frequency of the suspension obtained is improved.

[0067] Among them, the material of the wheels of the sliding trolley 21 can be hard plastic, such as polytetrafluoroethylene. This material has a light weight, and when the wheels of this material roll on a hard ground, the friction force is small.

[0068] Combined with the above embodiments, in one implementation, this embodiment provides a longitudinal mode test system for an automotive suspension system. The collision unit is arranged in front of the four sliding carts 21. The collision unit includes a collision block 31 and a rigid wall 32. The collision block 31 is fixed to the side of the rigid wall 32 facing the vehicle 1. The collision block 31 is used to simultaneously collide with the front ends of the two front wheels of the vehicle 1.

[0069] In this embodiment, the collision surface of the collision block 31 is perpendicular to the sliding direction of the sliding unit, and the collision surface is arranged opposite to the front ends of the two front wheels of the vehicle 1, so that when the vehicle 1 slides forward, the collision surface simultaneously collides with the foremost surfaces of the two front wheels of the vehicle 1. In the collision unit, the rigid wall 32 is fixed to the ground, and the collision block 31 is fixed to one side of the rigid wall 32. The collision block 31 is used to directly contact the two front wheels of the vehicle 1. The setting of the collision block 31 facilitates replacement after damage occurs during the collision; the collision surface of the collision block 31 is perpendicular to the radial direction of the vehicle 1, and the collision surface is arranged opposite to the front ends of the two front wheels of the vehicle 1 (i.e., the center points of the front end surfaces of the left and right front wheels of the vehicle 1), ensuring that the impact force received by the vehicle 1 suspension is radial, thereby ensuring the accuracy of the longitudinal mode test of the automotive suspension system, and reducing or even avoiding the excitation of the suspension lateral mode due to the lateral component of the impact force and contaminating the test data.

[0070] Among them, the distance between the initial placement position of the vehicle 1 and the collision surface of the collision block 31 is 1 m - 2 m. On the one hand, it enables the vehicle 1 to have enough distance to accelerate under the action of an external force to a speed that can collide with the collision block 31 and generate an easily identifiable mode. On the other hand, it avoids the vehicle 1 deviating from the forward direction due to being too far away from the collision block 31, resulting in the vehicle 1 not colliding with the collision block 31 or the collision angle deviating from the longitudinal direction.

[0071] Among them, the rigid wall 32 is fixedly connected to the ground, and the collision block 31 is fixed to the rigid wall 32 by bolts. On this basis, the height and lateral (left - right) position of the collision block 31 on the rigid wall 32 can be adjusted, so that the collision unit can be adapted to different vehicles 1.

[0072] Combined with the above embodiments, as Figures 4-5 shown, in one implementation, this embodiment provides a longitudinal mode test system for an automotive suspension system. Among them, the collision unit further includes a force sensor 33 arranged between the collision block 31 and the rigid wall 32. The force sensor 33 is used to detect the impact force signal received by the two front wheels during the collision; the force sensor 33 and all the tri - axial vibration acceleration sensors are respectively connected to the control unit in signal.

[0073] In this embodiment, the force sensor 33 serves as the above-mentioned impact force detection unit and is arranged between the bumper block 31 and the rigid wall 32. The force sensor 33 and all the three-axis vibration acceleration sensors are respectively connected to the control unit in a signal connection manner, and are used to transmit the impact force signal and the three-axis acceleration time-domain signals of the shock absorber spring 11, the subframe 12, the steering knuckle 13, and the swing arm 14 after the collision to the signal unit.

[0074] When the two front wheels of the vehicle 1 collide with the bumper block 31, the force sensor 33 can collect the longitudinal impact force and send the force signal during the collision to the control unit. Among them, this impact force can be regarded as the excitation force on the vehicle suspension. Thus, the control unit obtains the excitation force received by the vehicle suspension and the three-axis acceleration time-domain signals of each moving part of the vehicle suspension. Those skilled in the art can simply and quickly determine the modal frequency in the longitudinal direction of the suspension and the suspension motion form at the modal frequency based on the excitation force received by the vehicle suspension and the three-axis acceleration time-domain signals of each moving part of the vehicle suspension, which will not be elaborated here. Thus, by adding the force sensor 33 and combining with the three-axis acceleration time-domain signals of each moving part of the vehicle suspension, the modal frequency in the longitudinal direction of the suspension and the suspension motion form at the modal frequency can be simply and quickly determined, improving the efficiency of the longitudinal modal test.

[0075] Among them, the force sensor 33 can be connected to the data acquisition module 41 through a signal line. The data acquisition module 41 is used to collect the force signal of the force sensor 33 and transmit it to the acquisition computer 42.

[0076] Among them, the bumper block 31 and the force sensor 33 can be fixed to the rigid wall 32 simultaneously through the same bolts. When the bumper block 31 is impacted, it can directly transmit the impact force to the force sensor 33, improving the measurement accuracy of the force sensor 33.

[0077] It should be noted that for the method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the embodiments of the present application are not limited by the described action sequence, because according to the embodiments of the present application, some steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential for the embodiments of the present application.

[0078] Each embodiment in this specification is described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0079] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0080] Finally, it should also be noted that in this text, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such a process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the said element.

[0081] The above has introduced in detail a longitudinal mode test method and system for an automotive suspension system provided by the present application. Specific examples are used herein to illustrate the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A longitudinal mode testing method for an automotive suspension system, characterized in that, Including the steps: Reduce the frictional force between the vehicle and the ground when the vehicle slides forward, control the forward sliding of the vehicle, so that the front ends of the two front wheels of the vehicle are collided, and the vehicle rebounds after being collided; Monitor the three-axis acceleration time-domain signals of the shock absorber spring, subframe, steering knuckle and swing arm after the collision; Determine the suspension motion form at the longitudinal modal frequency of the suspension according to all the three-axis acceleration time-domain signals obtained by monitoring.

2. The longitudinal mode testing method for an automotive suspension system according to claim 1, wherein The step of determining the suspension motion form at the longitudinal modal frequency of the suspension according to all the three-axis acceleration time-domain signals obtained by monitoring includes: Extract the longitudinal acceleration time-domain signal from the three-axis acceleration time-domain signal of the steering knuckle; Determine the modal frequency of the suspension in the longitudinal direction according to the longitudinal acceleration time-domain signal of the steering knuckle after the collision; Determine the suspension motion form at the modal frequency according to all the three-axis acceleration time-domain signals obtained by monitoring.

3. A longitudinal mode testing method for an automotive suspension system according to claim 2, characterized in that The step of determining the modal frequency of the suspension in the longitudinal direction according to the longitudinal acceleration time-domain signal of the steering knuckle after the collision includes: Perform low-pass filtering on the longitudinal acceleration time-domain signal of the steering knuckle; Extract the times corresponding to the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle after low-pass filtering; Determine the average duration between the second and fourth acceleration peaks according to the extracted times; Take the reciprocal of the average duration to obtain the modal frequency of the suspension in the longitudinal direction.

4. A longitudinal mode test method for an automotive suspension system according to claim 1, characterized in that The step of determining the suspension motion form at the modal frequency according to all the three-axis acceleration time-domain signals obtained by monitoring includes: Perform working deformation analysis on all the three-axis acceleration time-domain signals obtained by monitoring to obtain the motion forms of the vehicle body and the suspension at the modal frequency; Based on the motion forms of the vehicle body and the suspension at the modal frequency, set the vehicle body as the reference system and determine the motion form of the suspension relative to the vehicle body; Determine the motion form of the suspension relative to the vehicle body as the suspension motion form at the modal frequency.

5. A longitudinal mode testing method for an automotive suspension system according to claim 1, characterized in that Before determining the suspension motion form at the longitudinal modal frequency of the suspension according to all the three-axis acceleration time-domain signals obtained by monitoring, it also includes the steps: Select a target three-axis acceleration time-domain signal from the three-axis acceleration time-domain signals of the shock absorber spring and the subframe; Perform modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle; In the case of passing the modal dominance verification, determine that all the three-axis acceleration time-domain signals can be used to determine the suspension motion form at the modal frequency; In the case of not passing the modal dominance verification, re-perform the longitudinal modal test to determine new three-axis acceleration time-domain signals.

6. A longitudinal mode testing method for an automotive suspension system according to claim 5, characterized in that Performing modal dominance verification on the target three-axis acceleration time-domain signal and the three-axis acceleration time-domain signal of the steering knuckle includes: Take the time period between the second and fourth acceleration peaks of the longitudinal acceleration time-domain signal of the steering knuckle as the verification time period; Determine the maximum acceleration of the steering knuckle within the verification time period according to the three-axis acceleration time-domain signal of the steering knuckle; Determine the maximum acceleration of the component corresponding to the target three-axis acceleration time-domain signal within the verification time period according to the target three-axis acceleration time-domain signal Compare the maximum acceleration of the steering knuckle with the maximum acceleration of the corresponding component of the target three-way acceleration time-domain signal to obtain the corresponding comparison result; Determine whether the modal dominance verification passes according to the comparison result.

7. A longitudinal mode test method for an automotive suspension system according to claim 1, characterized in that, It also includes the steps: Detect the impact force signals received by the two front wheels during a collision; The determining the suspension motion form at the longitudinal suspension modal frequency according to each three-way acceleration time-domain signal obtained by monitoring includes: According to the impact force signal and each of the three-way acceleration time-domain signals obtained by monitoring, determine the modal frequency of the longitudinal suspension and the suspension motion form at the modal frequency through modal analysis methods.

8. An automotive suspension system longitudinal mode test system, characterized in that, It includes: A sliding unit for fixing the wheels of the vehicle (1), reducing the friction between the vehicle (1) and the ground when the vehicle (1) slides forward, controlling the vehicle (1) to slide forward, and the vehicle (1) rebounds after being collided; A collision unit for causing the front ends of the two front wheels of the vehicle (1) to be collided; An acceleration monitoring unit including a plurality of three-way vibration acceleration sensors, and the plurality of three-way vibration acceleration sensors are respectively used to monitor the three-way acceleration time-domain signals of the shock absorber spring (11), the subframe (12), the steering knuckle (13) and the swing arm (14) after the collision; A control unit for determining the suspension motion form at the longitudinal suspension modal frequency according to the three-way acceleration time-domain signals of the shock absorber spring (11), the subframe (12), the steering knuckle (13) and the swing arm (14) after the collision.

9. The longitudinal mode test system for an automotive suspension system according to claim 8, wherein The sliding unit includes four sliding trolleys (21), and the four sliding trolleys (21) are used to respectively fix the four wheels of the vehicle (1), reduce the friction between the vehicle (1) and the ground when the vehicle (1) slides forward, control the vehicle (1) to slide forward, and the vehicle (1) rebounds after being collided; The collision unit is arranged in front of the four sliding trolleys (21), and the collision unit includes a bumper (31) and a rigid wall (32), the bumper (31) is fixed on the side of the rigid wall (32) facing the vehicle (1), and the bumper (31) is used to simultaneously cause the front ends of the two front wheels of the vehicle (1) to be collided.

10. The longitudinal mode test system for an automotive suspension system according to claim 9, characterized in that, The collision unit further includes a force sensor (33) arranged between the bumper (31) and the rigid wall (32), and the force sensor (33) is used to detect the impact force signals received by the two front wheels during the collision; The force sensor (33) and all the three-way vibration acceleration sensors are respectively connected to the control unit in a signal connection.

Images