Rear wheel steering gear testing method, device and system and control equipment

Abstract

The invention provides a rear wheel steering gear testing method, device and system and control equipment, and is applied to the field of vehicle testing. The rear wheel steering gear test system comprises a hysteresis brake, a displacement sensor and a control device. The method comprises the following steps: acquiring first displacement information of a rack when a step response test is performed on a rear wheel steering gear assembly, and determining a step response test result according to the first displacement information; when a step response test is carried out, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear wheel steering gear assembly; acquiring second displacement information of the rack when the frequency response test is performed on the rear wheel steering gear assembly, and determining a frequency response test result according to the second displacement information; and when the frequency response test is carried out, the hysteresis brake provides a second load force, and the control equipment issues a second control signal to the rear wheel steering gear assembly. The system and method provided by the invention can be suitable for the rear wheel steering gear, and the obtained test result is high in reliability.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle testing, and particularly to a method, device, system and control device for testing a rear-wheel steering gear. Background Art

[0002] With the continuous development of technology, more and more vehicles are beginning to be equipped with rear-wheel steering gears. In order to enhance the driving experience, the rear-wheel steering gear is required to have a high response speed, and improving the response speed of the rear-wheel steering gear requires accurate response test results of the rear-wheel steering gear.

[0003] In the related art, the testing of the steering gear is usually carried out based on an active load hydraulic cylinder. However, the response speed of the active load hydraulic cylinder is slow, the delay is relatively large, especially the response is not timely in the high-frequency band, which affects the reliability of the test results of the rear-wheel steering gear, and the cost is relatively high; in addition, the tests in the related art are all for the front-wheel steering gear or the test method for the front-wheel steering gear is simply improved and then used for the test of the rear-wheel steering gear. However, the control logic of the rear-wheel steering gear is different from that of the front-wheel steering gear, and the control accuracy requirement of the rear-wheel steering gear is relatively high. The test methods in the related art are not applicable to the rear-wheel steering gear. Summary of the Invention

[0004] Embodiments of the present application provide a method, device, system and control device for testing a rear-wheel steering gear to solve the problem that the existing test methods are not applicable to the rear-wheel steering gear or the reliability of the test results for the rear-wheel steering gear is poor.

[0005] In a first aspect, an embodiment of the present application provides a method for testing a rear-wheel steering gear, which is applied to a rear-wheel steering gear test system. The test system includes a hysteresis brake that provides a load force to a rear-wheel steering gear assembly, a displacement sensor that detects displacement information of a rack on the rear-wheel steering gear assembly, and a control device that is connected to the hysteresis brake, the displacement sensor and the rear-wheel steering gear assembly; The above method for testing a rear-wheel steering gear may include: Obtain the first displacement information of the rack when performing a step response test on the rear-wheel steering gear assembly, and determine the step response test result according to the first displacement information. When performing the step response test, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear-wheel steering gear assembly; Obtain the second displacement information of the rack when performing a frequency response test on the rear-wheel steering gear assembly, and determine the frequency response test result according to the second displacement information. When performing the frequency response test, the hysteresis brake provides a second load force, and the control device issues a second control signal to the rear-wheel steering gear assembly.

[0006] In the embodiment of the present application, a hysteresis brake is used to provide a load force for the rear wheel steering gear assembly. The hysteresis brake uses an electrical signal to control the load force instead of hydraulic drive, with a fast response speed and small delay. It can respond in a timely manner in both the low-frequency band and the high-frequency band, meeting the requirements of higher control precision for the rear wheel steering gear. Moreover, the hysteresis brake provides a passive load force, eliminating the need for a complex hydraulic system and reducing costs, which can lower the test cost. In addition, in the embodiment of the present application, a control device issues a control signal to the rear wheel steering gear assembly to simulate the control logic of the rear wheel steering gear assembly, and based on the test system, unique step response tests and frequency response tests are performed on the rear wheel steering gear assembly, covering the dynamic performance evaluation required for the "high-precision control" of the rear wheel steering gear assembly (such as fast response and high-frequency stability, etc.). It can be applied to the test of the rear wheel steering gear assembly, and the test results are highly reliable.

[0007] In a possible implementation manner, the determining the step response test result according to the first displacement information includes: According to the first displacement information, obtain the maximum actual displacement, the steady-state actual displacement, the starting time of the actual displacement, the first time when the actual displacement first reaches the first preset percentage of the steady-state actual displacement, and the second time when the actual displacement first reaches the second preset percentage of the steady-state actual displacement during the step response test; the first preset percentage is less than the second preset percentage; According to the first control signal, obtain the steady-state command displacement, the third time when the command displacement first reaches the first preset percentage of the steady-state command displacement, and the fourth time when the command displacement first reaches the second preset percentage of the steady-state command displacement during the step response test; Obtain the input time of the first control signal to the rear wheel steering gear assembly; Determine the step response test result according to the starting time of the actual displacement, the first time, the second time, the maximum actual displacement, the steady-state actual displacement, the third time, the fourth time, the input time, and the steady-state command displacement.

[0008] In the embodiment of the present application, the maximum actual displacement, the steady-state actual displacement, the starting time of the actual displacement, the first time, and the second time are obtained through the first displacement information, and combined with the steady-state command displacement, the third time, and the fourth time obtained through the first control signal, and combined with the input time of the first control signal to the rear wheel steering gear assembly, a complete step response curve feature library is constructed. Compared with the traditional method of simply measuring a single time parameter, the step response test result can be obtained by covering the entire "delay - rise - overshoot - stability" stage, meeting the requirements of the rear wheel steering gear's "high-precision control" for detailed parameters.

[0009] In a possible implementation, determining the step response test result according to the actual displacement start time, the first time, the second time, the actual displacement maximum value, the actual displacement steady state value, the third time, the fourth time, the input time, and the commanded displacement steady state value includes: Determine the dead time of the rear wheel steering gear assembly according to the actual displacement start time and the input time; Determine the response time of the rear wheel steering gear assembly according to the first time and the third time; Determine the execution time of the rear wheel steering gear assembly according to the second time and the fourth time; Determine the overshoot of the rear wheel steering gear assembly according to the actual displacement maximum value and the commanded displacement steady state value; Determine the steady state error of the rear wheel steering gear assembly according to the actual displacement steady state value and the commanded displacement steady state value.

[0010] In the embodiments of the present application, the step response test result is determined through the previously obtained step response curve feature library. The result includes the dead time, response time, execution time, overshoot, and steady state error of the rear wheel steering gear assembly, covering multiple dimensions such as delay, speed, accuracy, and stability, and can achieve a comprehensive quantitative evaluation of the step response of the rear wheel steering gear assembly, meeting the complex dynamic performance requirements in the actual working conditions.

[0011] In a possible implementation, the frequency of the second control signal changes from a first preset frequency to a second preset frequency in a preset step; The determining the frequency response test result according to the second displacement information includes: Obtain the actual peak displacement and the actual valley displacement at each frequency according to the second displacement information; Obtain the amplitude of the second control signal; Determine the amplitude attenuation ratio at each frequency according to the amplitude of the second control signal and the actual peak displacement and the actual valley displacement at each frequency; Generate an amplitude Bode plot according to the amplitude attenuation ratio at each frequency.

[0012] In the embodiment of the present application, the frequency of the second control signal changes from the first preset frequency to the second preset frequency according to a preset step, so as to cover the entire working frequency band of the rear-wheel steering gear assembly, obtain the actual peak displacement and the actual trough displacement at each frequency, and combine the amplitude of the second control signal to calculate the amplitude attenuation ratio at each frequency, so as to reflect the amplitude attenuation degree of the actual displacement relative to the command displacement, thereby testing whether the amplitude attenuation ratio of the rear-wheel steering gear assembly at each frequency meets the requirements; if the amplitude attenuation degree is too large, it may lead to a large difference between the actual steering angle of the vehicle's rear wheels and the command steering angle, resulting in the inability of the vehicle's rear wheels to turn in place. Therefore, in the embodiment of the present application, by obtaining the amplitude attenuation ratio at each frequency, it can be detected whether the rear-wheel steering gear assembly can make the vehicle's rear wheels turn in place; in addition, the amplitude Bode diagram is finally generated in the embodiment of the present application, which can intuitively display the amplitude attenuation degree at each frequency, so as to quickly identify the frequency bands that do not meet the requirements and guide the optimization of the rear-wheel steering gear assembly.

[0013] In a possible implementation manner, the frequency of the second control signal changes from the first preset frequency to the second preset frequency according to a preset step; The determining the frequency response test result according to the second displacement information includes: According to the second displacement information, obtain the actual peak time at each frequency; According to the second control signal, obtain the command peak time at each frequency; According to the actual peak time at each frequency, the command peak time at each frequency, and each frequency, determine the phase difference at each frequency; Generate a phase Bode diagram according to the phase difference at each frequency.

[0014] In the embodiment of the present application, the frequency of the second control signal changes from the first preset frequency to the second preset frequency according to a preset step, so as to cover the entire working frequency band of the rear-wheel steering gear assembly, obtain the actual peak time and the command peak time at each frequency, and combine each frequency to calculate the phase difference at each frequency, so as to reflect the phase delay degree of the actual displacement relative to the command displacement, thereby testing whether the phase delay degree of the rear-wheel steering gear assembly at each frequency meets the requirements; if the phase delay is too large, it may lead to the out-of-synchronization between the actual steering angle of the vehicle's rear wheels and the command steering angle, affecting the vehicle stability. Therefore, in the embodiment of the present application, by obtaining the phase difference at each frequency, it can be detected whether the rear-wheel steering gear assembly can make the vehicle drive stably; in addition, the phase Bode diagram is finally generated in the embodiment of the present application, which can intuitively display the phase delay degree at each frequency, so as to quickly identify the frequency bands that do not meet the requirements and guide the optimization of the rear-wheel steering gear assembly.

[0015] In a possible implementation manner, the first control signal is a square wave control signal, and the second control signal is a sine wave control signal; The first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear wheel steering gear assembly can withstand; the second load force is less than the first load force.

[0016] In the embodiment of the present application, the first control signal is a square wave control signal, and the first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear wheel steering gear assembly can withstand, so that the working condition of instantaneous steering under large load can be simulated, and the response ability of the rear wheel steering gear assembly under the condition of extreme input can be tested, so as to test whether the rear wheel steering gear assembly can meet the requirement of high response speed. If the rear wheel steering gear assembly can meet the requirement of high response speed under the large load working condition, it will surely be able to meet the requirement of high response speed under the small load working condition; the second control signal is a sine wave control signal, and the second load force is less than the first load force, so that the working condition with variable frequency under typical load can be simulated, and whether the amplitude, phase, etc. of the rear wheel steering gear assembly meet the requirements under this working condition can be tested; the embodiment of the present application can realize the test of the rear wheel steering gear assembly under multiple working conditions, and avoid the problem of incomplete coverage of working conditions caused by single working condition test.

[0017] In a possible implementation manner, the rear wheel steering gear test system further includes a baffle plate located on the rack, a load sensor for detecting the load force provided by the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear wheel steering gear assembly through the communication and power supply device; The baffle plate and the displacement sensor cooperate to detect the displacement information of the rack.

[0018] In the embodiment of the present application, through the cooperation of the baffle plate and the displacement sensor, the problem of large displacement detection error caused by some gaps of the test bench can be avoided, and the displacement detection accuracy can be improved; through the load sensor, the magnitude of the load force provided by the hysteresis brake can be fed back in real time, and the test error caused by the load force fluctuation can be avoided; through the communication and power supply device, data interaction and power supply between the control device and the rear wheel steering gear assembly can be realized, meeting the test requirements.

[0019] In a second aspect, the embodiment of the present application provides a rear wheel steering gear test device, which is applied to a rear wheel steering gear test system. The test system includes a hysteresis brake that provides a load force to the rear wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear wheel steering gear assembly, and a control device connected to the hysteresis brake, the displacement sensor, and the rear wheel steering gear assembly; The above-mentioned rear-wheel steering gear test device includes: A step response test module, configured to obtain first displacement information of the rack when performing a step response test on the rear-wheel steering gear assembly, and determine a step response test result according to the first displacement information; when performing a step response test, a hysteresis brake provides a first load force, and a control device issues a first control signal to the rear-wheel steering gear assembly; A frequency response test module, configured to obtain second displacement information of the rack when performing a frequency response test on the rear-wheel steering gear assembly, and determine a frequency response test result according to the second displacement information; when performing a frequency response test, a hysteresis brake provides a second load force, and a control device issues a second control signal to the rear-wheel steering gear assembly.

[0020] In a third aspect, an embodiment of the present application provides a control device, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, it implements the rear-wheel steering gear test method as described in the first aspect or any possible implementation manner of the first aspect.

[0021] In a fourth aspect, an embodiment of the present application provides a rear-wheel steering gear test system, including a hysteresis brake that provides a load force to the rear-wheel steering gear assembly, a displacement sensor that detects displacement information of a rack on the rear-wheel steering gear assembly, and a control device as described in the third aspect; The hysteresis brake, the displacement sensor, and the rear-wheel steering gear assembly are all connected to the control device.

[0022] In a possible implementation manner, the rear-wheel steering gear test system further includes a baffle located on the rack, a load sensor for detecting the load force of the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear-wheel steering gear assembly through the communication and power supply device; The baffle and the displacement sensor cooperate to detect the displacement information of the rack.

[0023] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the rear-wheel steering gear test method as described in the first aspect or any possible implementation manner of the first aspect.

[0024] In a sixth aspect, an embodiment of the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the rear-wheel steering gear test method in the above-mentioned first aspect or any possible implementation manner of the first aspect.

[0025] It is understandable that the beneficial effects of the above-mentioned second to sixth aspects can be referred to the relevant descriptions in the above-mentioned first aspect, and will not be elaborated here.

[0026] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and do not limit this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 is a schematic structural diagram of a rear-wheel steering gear test system provided by an embodiment of the present application; Figure 2 is a schematic flow diagram of a rear-wheel steering gear test method provided by an embodiment of the present application; Figure 3 is a schematic diagram of a first control signal and a first actual displacement curve provided by an embodiment of the present application; Figure 4 is a schematic diagram of a second control signal and a second actual displacement curve provided by an embodiment of the present application; Figure 5 is a schematic diagram of an amplitude Bode plot provided by an embodiment of the present application; Figure 6 is a schematic diagram of a phase Bode plot provided by an embodiment of the present application; Figure 7 is a schematic structural diagram of a rear-wheel steering gear test device provided by an embodiment of the present application; Figure 8 is a schematic structural diagram of a control device provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following further clarifies the present application with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the functions of the present application, but do not limit the present application in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made. These all belong to the protection scope of the present application.

[0030] It should be understood that, as used in the specification of this application and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups.

[0031] It should also be understood that the term "and / or" as used in the specification of this application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] In the description of the specification of this application and the appended claims, the terms "first", "second", "third", etc. are only used for differential description and should not be construed as indicating or implying relative importance.

[0033] Reference to "one embodiment" or "some embodiments" etc. described in the specification of this application means that a particular feature, structure or characteristic described in connection with that embodiment is included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0034] In addition, "a plurality" mentioned in the embodiments of this application should be construed as two or more.

[0035] With the continuous development of technology, more and more vehicles begin to be equipped with rear-wheel steering gears. In order to enhance the driving experience and enable the rear-wheel steering gear to achieve a driving experience similar to the following feel of the front-wheel steering gear, the rear-wheel steering gear needs to have a high response speed so as to be able to respond to driving demands in a timely manner, and improving the response speed of the rear-wheel steering gear requires based on accurate response test results of the rear-wheel steering gear.

[0036] In the related art, the testing of a steering gear is usually carried out based on an active load hydraulic cylinder. However, the active load hydraulic cylinder relies on the pressure transmission of hydraulic oil to achieve load control. The flow of the oil has inertia and resistance, and the oil itself has a certain compressibility, and it takes time to build pressure. At the same time, the movement of mechanical components (such as pistons, valves, etc.) also has inertia, resulting in a large response delay and a slow response speed of the active load hydraulic cylinder. Especially in the high-frequency band, the response is not timely. The control accuracy of the rear-wheel steering gear is usually at the millisecond level, and the response delay of the active load hydraulic cylinder will affect the reliability of the test results of the rear-wheel steering gear, and the cost of the hydraulic cylinder is relatively high; in addition, when using a hydraulic cylinder to perform a response test on the steering gear, more than one hydraulic cylinder may be required, resulting in a more complex setup of the test system bench and further increasing the cost.

[0037] In addition, the testing of the steering gear in the related art is either for the front-wheel steering gear or a simple improvement of the testing method for the front-wheel steering gear is used for the testing of the rear-wheel steering gear. However, the control logic of the rear-wheel steering gear is different from that of the front-wheel steering gear. For example, the front-wheel steering gear completes steering based on the control of the steering wheel, while the rear-wheel steering gear completes steering by sending commands to the motor therein, etc. Moreover, the control accuracy requirement of the rear-wheel steering gear is relatively high. The testing methods in the related art have strong limitations and cannot be directly applied to the rear-wheel steering gear, or the accuracy of the test results obtained when used for the testing of the rear-wheel steering gear is relatively poor.

[0038] To solve the above problems, the embodiments of the present application provide a testing method for a rear-wheel steering gear. The testing method for the rear-wheel steering gear is applied to a rear-wheel steering gear testing system; the testing system uses a hysteresis brake to provide a load force for the rear-wheel steering gear assembly, which can respond in a timely manner both in the low-frequency band and the high-frequency band, can meet the requirements of the relatively high control accuracy of the rear-wheel steering gear, and has a relatively low cost, which can reduce the testing cost; in addition, a control signal is sent to the rear-wheel steering gear assembly by a control device to simulate the control logic of the rear-wheel steering gear assembly, and a unique step response test and frequency response test are performed on the rear-wheel steering gear assembly based on the testing system, covering the dynamic performance evaluation required for the "high-precision control" of the rear-wheel steering gear assembly, and can be applied to the testing of the rear-wheel steering gear assembly, and the reliability of the test results is relatively high.

[0039] The following will refer to Figure 1 for a detailed introduction to the rear-wheel steering gear testing system. It should be noted that Figure 1 the rear-wheel steering gear testing system shown is only for facilitating the understanding of the spirit and principle of the present application, and the embodiments of the present application are not restricted in this regard. On the contrary, the embodiments of the present application can be applied to any applicable rear-wheel steering gear testing system.

[0040] Refer to Figure 1, the rear-wheel steering gear test system may include a hysteresis brake 11 that provides a load force to the rear-wheel steering gear assembly 10, a displacement sensor 12 that detects the displacement information of the rack on the rear-wheel steering gear assembly 10, and a control device 800 connected to the hysteresis brake 11, the displacement sensor 12, and the rear-wheel steering gear assembly 10.

[0041] Among them, the rear-wheel steering gear test system may be abbreviated as the test system.

[0042] The hysteresis brake 11 is a torque control component that utilizes the hysteresis principle. It can utilize the hysteresis principle to generate a certain torque by controlling the input exciting current and provide a load force to the rear-wheel steering gear assembly 10. Among them, there is a good linear relationship between the control current and the output torque of the hysteresis brake 11. The hysteresis brake 11 can provide smooth, steplessly adjustable, speed-independent torque control, can provide a passive load force, and has no other friction inside except for the bearings. It has the advantages of stable and reliable operation, high operating speed, low noise, long service life, and low maintenance cost.

[0043] Compared with the active load hydraulic cylinder, the hysteresis brake 11 has the advantages of fast response and small delay. It adjusts the torque output by controlling the exciting current. The transmission and response speed of the electrical signal are extremely fast, and the energy conversion is direct (electrical energy → magnetic field energy → torque) without complex intermediate links. For example, when the exciting current changes, the magnetic field responds immediately, and the torque changes accordingly. The delay is mainly determined by the circuit time constant, usually in the millisecond or even microsecond level. The hysteresis brake 11 mostly adopts non-contact torque transmission without mechanical friction and clearance. For example, when the rotor rotates in the magnetic field, it only needs to overcome extremely small bearing friction, and the magnetic pole conversion is rapid without mechanical hysteresis. The torque output of the hysteresis brake 11 has good followability to current changes and can quickly respond to high-frequency dynamic signals. For example, in high-frequency vibration tests, it can adjust the torque in real time to meet the rapidly changing load requirements.

[0044] With the characteristics of direct control by electrical signals, non-contact transmission, and fast energy conversion, the hysteresis brake 11 is significantly superior to the active load hydraulic cylinder in terms of response speed and delay control, and is more suitable for scenarios with high requirements for dynamic response. For example, in the scenario of testing the rear-wheel steering gear assembly 10 in the embodiments of the present application.

[0045] The hysteresis brake 11 can be connected to the single-sided pull rod (right pull rod) of the rear-wheel steering gear assembly 10 to provide a load force to the rear-wheel steering gear assembly 10, and the load force it provides to the rear-wheel steering gear assembly 10 is a passive load force. The magnetoresistive brake can be controlled by the control device 800 and provide the required load force to the rear-wheel steering gear assembly 10 according to the instructions issued by the control device 800.

[0046] The rear-wheel steering gear assembly 10 is a by-wire product, which may include at least one of components such as a rear-wheel steering component, a drive motor, a controller, a rack, a tie rod, and a connection structure. The rear-wheel steering gear assembly 10 may be an actual rear-wheel steering gear assembly installed in a vehicle, or a prototype made based on the actual rear-wheel steering gear assembly installed in a vehicle. The components it includes and the connection relationships between the components can be referred to the introductions in related technologies and will not be elaborated here. The rear-wheel steering gear assembly 10 may also be referred to as a rear-wheel electric power steering gear assembly or a rear-wheel by-wire steering gear assembly.

[0047] The rear-wheel steering gear assembly 10 is controlled by a control device 800. When testing the rear-wheel steering gear assembly 10, the control device 800 sends corresponding control signals to the rear-wheel steering gear assembly 10 to control the operation of the drive motor of the rear-wheel steering gear assembly 10. The operation of the drive motor drives the movement of the rack on the rear-wheel steering gear assembly 10. Therefore, by setting a displacement sensor 12, the displacement information of the rack on the rear-wheel steering gear assembly 10 can be detected.

[0048] The displacement sensor 12 is communicatively connected to the control device 800, so that the detected displacement information of the rack can be sent to the control device 800.

[0049] The control device 800 is the control center of the rear-wheel steering gear test system, which can be communicatively connected to the displacement sensor 12 and the hysteresis brake 11, and can also be communicatively connected and electrically connected to the rear-wheel steering gear assembly 10. The control device 800 may be a host computer or other control devices 800 that can implement corresponding functions, and no specific restrictions are made here.

[0050] In related technologies, when using an active load hydraulic cylinder to perform a response test on a steering gear, it is usually necessary to ensure that the load force applied by the hydraulic cylinder to the rear-wheel steering gear assembly 10 and the process of the rear-wheel steering gear assembly 10 executing corresponding actions according to the control signals sent by the control device 800 are completed in the same time domain. That is to say, it is necessary to control the hydraulic cylinder and the rear-wheel steering gear assembly 10 simultaneously. However, in the embodiments of the present application, the hysteresis brake 11 is used to provide the load force, and it can provide a passive load force. Therefore, it is not necessary to control the hysteresis controller and the rear-wheel steering gear assembly 10 simultaneously. Only a load force signal needs to be given to the hysteresis controller, and then only the rear-wheel steering gear assembly 10 needs to be controlled, and there is no need to control the hysteresis controller anymore (unless it is necessary to change the magnitude of the load force provided by the hysteresis controller, then a load force signal needs to be sent to it again), and the control method is relatively simple.

[0051] In some possible implementation manners, referring to Figure 1 , the rear-wheel steering gear test system may further include a baffle 14 located on the rack; the baffle 14 cooperates with the displacement sensor 12 to detect the displacement information of the rack.

[0052] The displacement sensor 12 can be a laser sensor. By emitting a laser to the baffle 14 and receiving the reflected light information, the displacement information of the rack is detected.

[0053] See Figure 1 , the baffle 14 can be arranged on the left rack of the rear-wheel steering gear assembly 10, and the displacement sensor 12 can be arranged on its housing bracket. The two cooperate to detect the displacement information of the rack.

[0054] In some possible implementation manners, see Figure 1 , the rear-wheel steering gear test system may further include a load sensor 15 for detecting the load force provided by the hysteresis brake 11.

[0055] The load sensor 15 can be used to detect the load force provided by the hysteresis brake 11, or to detect the load force received by the rear-wheel steering gear assembly 10. See Figure 1 , the load sensor 15 can be located between the rear-wheel steering gear assembly 10 and the hysteresis brake 11. Specifically, one side tie rod of the rear-wheel steering gear assembly 10 is connected to the load sensor 15, and the load sensor 15 is also connected to the hysteresis brake 11.

[0056] The load sensor 15 is also communicatively connected to the control device 800 for sending the detected load force to the control device 800.

[0057] In addition to being able to perform some calculations on the received information, etc., the control device 800 can also display and save the received information, etc.

[0058] Exemplarily, when it is necessary to test the rear-wheel steering gear assembly 10, the control device 800 can send a load force signal to the hysteresis brake 11, and the load force signal carries the magnitude of the load force that the hysteresis brake 11 needs to provide. After receiving the load force signal, the hysteresis brake 11 outputs according to the load force signal so that the load force it provides meets the requirements of the load force signal. At the same time, the load sensor 15 can detect the magnitude of the load force provided by the hysteresis brake 11 and send the detected load force to the control device 800, so that the control device 800 can monitor in real time whether the magnitude of the load force provided by the hysteresis brake 11 meets the requirements.

[0059] The rear-wheel steering gear test system provided by the embodiments of the present application may only include one hysteresis brake 11 and one load sensor 15. Compared with the need for multiple hydraulic cylinders and multiple load sensors 15 when testing with an active load hydraulic cylinder, the cost can be greatly saved.

[0060] It should be noted that according to actual usage requirements, the rear-wheel steering gear test system provided in the embodiments of the present application may also include a plurality of hysteresis brakes 11 and a plurality of load sensors 15. The embodiments of the present application do not specifically limit the numbers of the hysteresis brakes 11 and the load sensors 15.

[0061] In some possible implementation manners, referring to Figure 1 , the rear-wheel steering gear test system may further include a communication and power supply device 16; the control device 800 is connected to the rear-wheel steering gear assembly 10 through the communication and power supply device 16.

[0062] The communication and power supply device 16 may also be referred to as a power cord, a CAN line ignition device.

[0063] The control device 800 can provide an effective voltage for the communication and power supply device 16, and ignite or power on the drive motor in the rear-wheel steering gear assembly 10 through the communication and power supply device 16; the control device 800 can also communicate with the rear-wheel steering gear assembly 10 through the communication and power supply device 16 for data transmission. Specifically, it can directly communicate with the drive motor to control the operation of the drive motor and receive the feedback information of the drive motor; it can also communicate with the controller in the rear-wheel drive assembly. The controller is connected to the drive motor, and the drive motor can be controlled to operate and the feedback information of the drive motor can be received through the controller.

[0064] In some possible implementation manners, referring to Figure 1 , the rear-wheel steering gear test system may further include a first mounting block 17 and a second mounting block 18. The rear-wheel steering gear assembly 10 is mounted on the first mounting block 17 and the second mounting block 18, and the core shaft of the rear-wheel steering gear assembly 10 can be located at the middle position between the first mounting block 17 and the second mounting block 18.

[0065] In some possible implementation manners, referring to Figure 1 , the rear-wheel steering gear test system may further include a third mounting block 19. The load sensor 15 and the hysteresis brake 11 can be mounted on the third mounting block 19.

[0066] The rear-wheel steering gear test system provided by the embodiment of the present application uses a hysteresis brake 11 to provide a load force for the rear-wheel steering gear assembly 10. The hysteresis brake 11 controls the load force with an electrical signal instead of hydraulic drive, has a fast response speed and small delay, and can respond in a timely manner whether in the low-frequency band or the high-frequency band, which can meet the requirements of higher control accuracy of the rear-wheel steering gear. Moreover, the hysteresis brake 11 provides a passive load force, without a complex hydraulic system, with a lower cost, which can reduce the test cost. At the same time, the control method is simple and there is no strict requirement for simultaneous control; the displacement sensor 12 cooperates with the baffle 14 to accurately detect the displacement information of the rack and feedback the displacement information; the load sensor 15 can real-time feedback the magnitude of the load force provided by the hysteresis brake 11 to avoid test errors caused by load force fluctuations; through the communication and power supply device 16, data interaction and power supply between the control device 800 and the rear-wheel steering gear assembly 10 can be realized to meet the test requirements. The rear-wheel steering gear test system provided by the embodiment of the present application can solve the problem of the lack of a test system for the rear-wheel steering gear and can provide a basis for the rear-wheel steering gear test method.

[0067] Corresponding to the above rear-wheel steering gear test system, the embodiment of the present application also provides a rear-wheel steering gear test method. The following combines Figure 1 the rear-wheel steering gear test system, and refers to Figures 2 - 6 to describe the rear-wheel steering gear test method provided according to the exemplary embodiment of the present application.

[0068] The rear-wheel steering gear test method provided by the embodiment of the present application can be applied to the rear-wheel steering gear test system. As described above, the test system can include a hysteresis brake that provides a load force for the rear-wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear-wheel steering gear assembly, and a control device connected to the hysteresis brake, the displacement sensor, and the rear-wheel steering gear assembly. The specific description of the test system can refer to the relevant introduction in the foregoing embodiment and will not be elaborated here.

[0069] It should be noted that the embodiment of the present application is specifically applied to the above control device, and the control device can be an upper computer, a computing terminal device, a server, etc., that is, the rear-wheel steering gear test method provided by the exemplary embodiment of the present application can be executed on the upper computer, the computing terminal device, or the server.

[0070] It should be noted that the rear-wheel steering gear test method provided according to the exemplary embodiment of the present application can be executed on the same device or on different devices.

[0071] Figure 2 is a schematic flowchart of the rear-wheel steering gear test method provided by an embodiment of the present application. As Figure 2 shown, the rear-wheel steering gear test method in the embodiment of the present application can include: Step 201: Obtain the first displacement information of the rack during the step response test of the rear wheel steering gear assembly, and determine the step response test result based on the first displacement information. During the step response test, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear wheel steering gear assembly.

[0072] In an embodiment of the present application, the hysteresis brake is controlled to provide a first load force to the rear wheel steering gear assembly and issue a first control signal to the rear wheel steering gear assembly to perform a step response test on the rear wheel steering gear assembly. Among them, the step response test simulates the instantaneous steering condition under a large load. The first load force can be a relatively large load force, and the first control signal is used to instruct the rear wheel steering gear assembly to perform an instantaneous steering. The first control signal may include first command displacement information, that is, it is desired to control the rack of the rear wheel steering gear assembly to move according to the first command displacement information to complete the step response test. The step response test is to test the response data of the rear wheel steering gear assembly during instantaneous steering.

[0073] During the step response test of the rear wheel steering gear assembly, the hysteresis brake can provide a constant load, that is, keep the first load force unchanged.

[0074] Based on the displacement sensor, the first displacement information of the rack during the step response test of the rear wheel steering gear assembly can be obtained. Furthermore, based on the first displacement information and the first control signal, the difference between the two can be compared to determine the step response test result of the step response test of the rear wheel steering gear assembly. Exemplarily, according to the first displacement information, the first characteristic information of the actual displacement of the rack can be obtained, according to the first control signal, the second characteristic information of the commanded displacement of the rack can be obtained, and based on the first characteristic information and the second characteristic information, the step response test result can be determined.

[0075] The embodiment of the present application does not specifically limit the specific implementation manner of determining the step response test result based on the first displacement information. In related technologies, any implementable manner can be used.

[0076] Step 202: Obtain the second displacement information of the rack during the frequency response test of the rear wheel steering gear assembly, and determine the frequency response test result based on the second displacement information. During the frequency response test, the hysteresis brake provides a second load force, and the control device issues a second control signal to the rear wheel steering gear assembly.

[0077] In the embodiment of the present application, the hysteresis brake is controlled to provide a second load force to the rear wheel steering gear assembly and issue a second control signal to the rear wheel steering gear assembly to perform a frequency response test on the rear wheel steering gear assembly. Among them, the frequency response test simulates working conditions with different frequencies under bumpy road conditions, such as working conditions with different frequencies on cobblestone roads, and so on. Under this working condition, the load force is usually not large. Therefore, the second load force can be smaller than the first load force and can be a relatively small load force. The second control signal is used to indicate that the displacement change frequency of the rack of the rear wheel steering gear assembly gradually changes. The second control signal may include second command displacement information, that is, it is desired to control the rack of the rear wheel steering gear assembly to move according to the second command displacement information to complete the frequency response test. The frequency response test is to test the response data of the rear wheel steering gear assembly at different frequencies.

[0078] When performing a frequency response test on the rear wheel steering gear assembly, the hysteresis brake can provide a constant load, that is, keep the second load force unchanged.

[0079] Based on the displacement sensor, the second displacement information of the rack during the frequency response test on the rear wheel steering gear assembly can be obtained. Furthermore, based on the second displacement information and the second control signal, the differences in amplitude and phase between the two can be compared to determine the frequency response test result of the frequency response test on the rear wheel steering gear assembly. Exemplarily, according to the second displacement information, the third characteristic information of the actual displacement of the rack can be obtained, and according to the second control signal, the fourth characteristic information of the commanded displacement of the rack can be obtained. Based on the third characteristic information and the fourth characteristic information, the frequency response test result can be determined.

[0080] The embodiment of the present application does not specifically limit the specific implementation manner of determining the frequency response test result according to the second displacement information above. In related technologies, any implementable manner can be used.

[0081] It should be noted that the embodiment of the present application does not specifically limit the execution order of step 201 and step 202. Step 201 can be executed first, and then step 202; or step 202 can be executed first, and then step 201; and so on.

[0082] Before executing step 201 and step 202, it is first necessary to arrange the test system, that is, arrange the rear wheel steering gear assembly on the corresponding mounting block, arrange the resignation brake, displacement sensor, etc. to the corresponding positions, and arrange the connection relationship between them, and so on.

[0083] In the embodiments of the present application, a hysteresis brake is used to provide a load force for the rear-wheel steering gear assembly. The hysteresis brake uses an electrical signal to control the load force instead of hydraulic drive, with a fast response speed and small delay. It can respond in a timely manner in both the low-frequency band and the high-frequency band, meeting the requirements of higher control accuracy for the rear-wheel steering gear. Moreover, the hysteresis brake provides a passive load force, eliminating the need for a complex hydraulic system, resulting in lower costs, which can reduce the test cost, and is easy to operate with simple bench setup. In addition, in the embodiments of the present application, the control device issues a control signal to the rear-wheel steering gear assembly, which can simulate the control logic of the rear-wheel steering gear assembly. Based on the test system, unique step response tests and frequency response tests are conducted on the rear-wheel steering gear assembly, covering the dynamic performance evaluation required for the "high-precision control" of the rear-wheel steering gear assembly (such as fast response and high-frequency stability, etc.), being applicable to the test of the rear-wheel steering gear assembly with high test result reliability.

[0084] The overall process of the rear-wheel steering gear test method was introduced in the foregoing embodiments, which involves step response tests and frequency response tests. Next, how to determine the step response test results and frequency response test results will be introduced in sequence. To introduce the two more clearly, first, the first load force, the second load force, the first control signal, and the second control signal involved are introduced.

[0085] In some embodiments, the first control signal is a square-wave control signal, and the second control signal is a sine-wave control signal; The first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear-wheel steering gear assembly can withstand; the second load force is less than the first load force.

[0086] Since the step response test is to simulate the instantaneous steering condition under a large load, the first load force is a relatively large load force, which can be the maximum load force that the hysteresis brake can provide or the maximum load force that the rear-wheel steering gear assembly can withstand, or slightly smaller than the maximum load force that the hysteresis brake can provide or slightly smaller than the maximum load force that the rear-wheel steering gear assembly can withstand, etc.; the first control signal is a square-wave control signal, simulating an instantaneous increase in displacement, as Figure 3 shown in 31 in.

[0087] If the step response test results of the rear-wheel steering gear assembly under a large load can meet the requirements, then the step response of the rear-wheel steering gear assembly under a small load can also meet the requirements. Therefore, in the embodiments of the present application, it is only necessary to conduct a step response test on the rear-wheel steering gear assembly under a large load.

[0088] The frequency response test needs to simulate a bumpy road condition and test the amplitude attenuation ratio and phase difference at different frequencies. This test is usually carried out under a small load. Therefore, the second load force is less than the first load force and can be a relatively small load force. The second control signal is a sine wave control signal. Compared with other signals, the sine wave is easier to analyze the amplitude-frequency and phase-frequency characteristics and easier to obtain accurate frequency response test results. The second control signal is as shown in Figure 4 41 in

[0089] When performing a step response test and a frequency response test on the rear wheel steering gear assembly, the vehicle speed is usually 0. The amplitudes of the first control signal and the second control signal can be set according to actual needs and are not specifically limited here. For example, they can be set according to the corresponding working conditions, etc.

[0090] In the embodiment of the present application, the first control signal is a square wave control signal, and the first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear wheel steering gear assembly can withstand. Thus, the working condition of instantaneous steering under a large load can be simulated to test the response ability of the rear wheel steering gear assembly under the condition of extreme input, so as to test whether the rear wheel steering gear assembly can meet the requirement of high response speed. If the rear wheel steering gear assembly can meet the requirement of high response speed under the large load working condition, it will surely be able to meet the requirement of high response speed under the small load working condition. The second control signal is a sine wave control signal, and the second load force is less than the first load force. Thus, the working condition with variable frequencies under a typical load can be simulated to test whether the amplitude, phase, etc. of the rear wheel steering gear assembly meet the requirements under this working condition. The embodiment of the present application can realize the test of the rear wheel steering gear assembly under multiple working conditions and avoid the problem of incomplete working condition coverage caused by single working condition test.

[0091] Next, continue to introduce how to determine the step response test result.

[0092] In some embodiments, in step 201, determining the step response test result according to the first displacement information includes: According to the first displacement information, obtain the maximum actual displacement, the steady-state actual displacement, the starting time of the actual displacement, the first time when the actual displacement first reaches the first preset percentage of the steady-state actual displacement, and the second time when the actual displacement first reaches the second preset percentage of the steady-state actual displacement during the step response test; the first preset percentage is less than the second preset percentage; According to the first control signal, obtain the steady-state command displacement, the third time when the command displacement first reaches the first preset percentage of the steady-state command displacement, and the fourth time when the command displacement first reaches the second preset percentage of the steady-state command displacement during the step response test; Obtain the input time of the first control signal to the rear-wheel steering gear assembly; Determine the step response test result according to the actual displacement start time, the first time, the second time, the maximum actual displacement, the steady-state actual displacement value, the third time, the fourth time, the input time, and the commanded displacement steady-state value.

[0093] Among them, the first displacement information may include the correspondence between the displacement of the rack and time during the step response test of the rear-wheel steering gear assembly. According to the first displacement information, a corresponding first actual displacement curve can be generated, that is, the first actual displacement curve of the rack under the first control signal, as shown in Figure 3 shown in 32 of Figure 3 In

[0094] The maximum actual displacement is the maximum value of the ordinate of the first actual displacement curve 32.

[0095] The steady-state actual displacement value is the steady-state value of the ordinate of the first actual displacement curve 32, that is, the ordinate value after it finally reaches stability.

[0096] The actual displacement start time refers to the time or moment corresponding to when the ordinate value of the first actual displacement curve 32 starts to change after the first control signal is input, which is Figure 3 the time or moment corresponding to the second vertical dotted line starting from the left in

[0097] The first time is the time or moment when the ordinate value of the first actual displacement curve 32 first reaches the first preset percentage of the steady-state actual displacement value, which is Figure 3 the time or moment corresponding to the third vertical dotted line starting from the left in

[0098] The second time is the time or moment when the ordinate value of the first actual displacement curve 32 first reaches the second preset percentage of the steady-state actual displacement value, which is Figure 3 the time or moment corresponding to the fourth vertical dotted line starting from the left in

[0099] The first preset percentage is less than the second preset percentage, and their values can be set according to actual needs. Usually, the first preset percentage is 10% and the second preset percentage is 90%.

[0100] The steady-state value of the command displacement can be referred to as the maximum value of the command displacement, which is the maximum ordinate value of the first control signal 31. Since the first control signal 31 is a square wave signal, the steady-state value of the command displacement is the maximum value of the command displacement.

[0101] The third time is the time or moment when the ordinate value of the first control signal 31 first reaches the first preset percentage of the steady-state value of the command displacement. The fourth time is the time or moment when the ordinate value of the first control signal 31 first reaches the second preset percentage of the steady-state value of the command displacement. Since the first control signal 31 is a square wave signal and its ordinate value instantaneously becomes the maximum value, the third time and the fourth time can be the same moment, that is, Figure 3 the time or moment corresponding to the first vertical dotted line starting from the left in

[0102] The input time of the first control signal to the rear wheel steering gear assembly refers to the time or moment when the first control signal is input to the rear wheel steering gear assembly. This input time can be obtained according to the feedback information of the rear wheel steering gear assembly, or can be obtained by other means, which is not specifically limited here. Exemplarily, the input time can be Figure 3 the time or moment corresponding to the first vertical dotted line starting from the left in

[0103] In the embodiments of the present application, through the actual displacement start time, the first time, the second time, the actual displacement maximum value, the actual displacement steady-state value, the third time, the fourth time, the input time, and the command displacement steady-state value, the step response test result can be determined, but the specific implementation means for determining the step response test result are not specifically limited, and any achievable means can be used.

[0104] In the embodiments of the present application, the actual displacement maximum value, the actual displacement steady-state value, the actual displacement start time, the first time, and the second time are obtained through the first displacement information, and combined with the command displacement steady-state value, the third time, and the fourth time obtained through the first control signal, and combined with the input time of the first control signal to the rear wheel steering gear assembly, a complete step response curve feature library is constructed. Compared with the traditional method of simply measuring a single time parameter, the step response test result can be obtained by covering the entire "delay - rise - overshoot - steady" stage, meeting the requirements of the "high-precision control" of the rear wheel steering gear for detailed parameters.

[0105] Next, continue to introduce how to determine the step response test result according to the actual displacement start time, the first time, the second time, the actual displacement maximum value, the actual displacement steady-state value, the third time, the fourth time, the input time, and the command displacement steady-state value.

[0106] In some embodiments, determining the step response test result based on the actual displacement start time, the first time, the second time, the maximum actual displacement, the steady-state actual displacement value, the third time, the fourth time, the input time, and the steady-state commanded displacement value includes: Determining the dead time of the rear-wheel steering gear assembly according to the actual displacement start time and the input time; Determining the response time of the rear-wheel steering gear assembly according to the first time and the third time; Determining the execution time of the rear-wheel steering gear assembly according to the second time and the fourth time; Determining the overshoot of the rear-wheel steering gear assembly according to the maximum actual displacement and the steady-state commanded displacement value; Determining the steady-state error of the rear-wheel steering gear assembly according to the steady-state actual displacement value and the steady-state commanded displacement value.

[0107] In the embodiments of the present application, the step test response result may include the dead time, response time, execution time, overshoot, and steady-state error of the rear-wheel steering gear assembly.

[0108] Among them, the dead time is the wake-up time of the rear-wheel steering gear assembly, which is the difference obtained by subtracting the input time from the actual displacement start time. The dead time is as Figure 3 shown as A in

[0109] The response time may be the difference between the time when the actual displacement first reaches the first preset percentage of the steady-state actual displacement value and the time when the commanded displacement first reaches the first preset percentage of the steady-state commanded displacement value during the step response test of the rear-wheel steering gear assembly, that is, the difference between the first time and the third time. The response time is as Figure 3 shown as B in

[0110] In a second-order step response system, in order to more accurately describe and predict the step response of the second-order system, the transfer function and Laplace transform method can also be used. Specifically, the derivative calculation can be performed on the output first actual displacement curve to obtain the actual velocity curve; according to the actual velocity curve, the time corresponding to the initial velocity value and the time corresponding to the velocity peak value can be obtained; the difference between the time corresponding to the initial velocity value and the time corresponding to the velocity peak value is also the response time.

[0111] The execution time may be the difference between the time when the actual displacement first reaches the second preset percentage of the steady-state actual displacement value and the time when the commanded displacement first reaches the second preset percentage of the steady-state commanded displacement value during the step response test of the rear-wheel steering gear assembly, that is, the difference between the second time and the fourth time. The execution time is as Figure 3 shown as C in

[0112] The overshoot is the amount by which the maximum actual displacement of the rear-wheel steering gear assembly response exceeds the steady-state value of the commanded displacement. It can be expressed as a displacement difference or as a percentage. It is generally calculated after the actual displacement reaches the steady-state value of the commanded displacement. For example, the overshoot can be the difference obtained by subtracting the steady-state value of the commanded displacement from the maximum actual displacement, as shown by D in Figure 3 ; or it can be the percentage obtained by dividing this difference by the steady-state value of the commanded displacement and then multiplying by one hundred percent.

[0113] The steady-state error is the deviation between the actual output and the expected value during the long-term operation of the rear-wheel steering gear assembly. It is generally calculated after the rear-wheel steering gear assembly stabilizes. The steady-state error can be the difference between the steady-state value of the actual displacement and the steady-state value of the commanded displacement, as shown by E in Figure 3 ;

[0114] After obtaining the step response test results in the embodiments of the present application, the above-mentioned dead time, response time, execution time, overshoot, and steady-state error can be compared with their respective standard thresholds to determine whether the step response of the rear-wheel steering gear assembly meets the requirements. If not, the rear-wheel steering gear assembly can be optimized according to the step response test results to make it meet the requirements.

[0115] In the embodiments of the present application, based on the previously obtained step response curve feature library, the step response test results are determined. The results include the dead time, response time, execution time, overshoot, and steady-state error of the rear-wheel steering gear assembly, covering multiple dimensions such as delay, speed, accuracy, and stability, and can achieve a comprehensive quantitative evaluation of the step response of the rear-wheel steering gear assembly, meeting the complex dynamic performance requirements in the actual working conditions.

[0116] In some possible implementation manners, there is a certain corresponding relationship between the displacement of the rack and the angle of the drive motor. In addition to collecting the displacement of the rack to obtain the step response test results, the angle of the drive motor can also be collected or the angle of the drive motor can be calculated based on the memorized displacement of the rack, and then the step response test results can be obtained based on the angle of the drive motor.

[0117] Next, continue to introduce how to determine the frequency response test results according to the second displacement information.

[0118] In some embodiments, the frequency of the second control signal changes from the first preset frequency to the second preset frequency at a preset step size; In step 202, the above-mentioned determining the frequency response test results according to the second displacement information includes: Obtaining the actual peak displacement and the actual valley displacement at each frequency according to the second displacement information; Obtaining the amplitude of the second control signal; Determine the amplitude attenuation ratio at each frequency according to the amplitude of the second control signal and the actual peak displacement and actual valley displacement at each frequency; Generate an amplitude Bode plot according to the amplitude attenuation ratio at each frequency.

[0119] Among them, the first preset frequency and the second preset frequency can be determined according to the full frequency band that the rear wheel steering gear assembly can cover. The first preset frequency and the second preset frequency are respectively the minimum frequency and the maximum frequency of the full frequency band. The first preset frequency can be less than the second preset frequency, that is, the first preset frequency is the minimum frequency and the second preset frequency is the maximum frequency, that is, the frequency of the second control signal changes from small to large; or, the first preset frequency can be greater than the second preset frequency, that is, the first preset frequency is the maximum frequency and the second preset frequency is the minimum frequency, that is, the frequency of the second control signal changes from large to small.

[0120] The size of the preset step can be set according to actual needs. Exemplarily, the first preset frequency can be 0.1 Hz, the second preset frequency can be 3.5 Hz, and the preset step can be 0.1 Hz.

[0121] It should be noted that each frequency in the second control signal lasts at least one period.

[0122] When performing the frequency response test, it is also necessary to compare the second control signal with the second actual displacement curve.

[0123] Exemplarily, the second control signal is as Figure 4 shown in 41, and the amplitude of the second control signal is as Figure 4 shown as A2 in; the second actual displacement curve is as Figure 4 shown in 42, and the amplitude of the second actual displacement curve is as Figure 4 shown as A3 in.

[0124] In the embodiments of the present application, the Calculate Peaks function can be used to take points of peaks and valleys on the second actual displacement curve to obtain the actual peak displacement (i.e., the ordinate value of the actual peak) and actual valley displacement (i.e., the ordinate value of the actual valley) at each frequency. Each frequency corresponds to at least one actual peak displacement and at least one actual valley displacement. Take the absolute value of the actual valley displacement corresponding to each frequency, and determine the amplitude attenuation ratio at each frequency according to the actual peak displacement corresponding to each frequency, the absolute value of the actual valley displacement, and the amplitude of the second control signal.

[0125] Specifically, for each frequency, if the frequency corresponds to an actual peak displacement and an actual valley displacement, the sum of the actual peak displacement corresponding to the frequency and the absolute value of the actual valley displacement can be calculated, and the first value after summation is divided by twice the amplitude of the second control signal, and then the obtained value is multiplied by 100% to obtain the amplitude attenuation ratio of the frequency; if the frequency corresponds to at least two actual peak displacements or at least two actual valley displacements, the average value of the actual peak displacements can be first calculated to obtain the average actual peak displacement, and the average value of the actual valley displacements can be calculated to obtain the average actual valley displacement, and then based on the average actual peak displacement and the average actual valley displacement, the amplitude attenuation ratio of the frequency can be calculated.

[0126] According to the amplitude attenuation ratios at various frequencies, the Generate Numeric function can be used to set a curve with M3 points, and the corresponding amplitude attenuation ratio is the amplitude attenuation result, and an amplitude Bode plot is generated. Wherein, M3 is the number of the above frequencies.

[0127] Specifically, an amplitude Bode plot with the frequency as the abscissa and the amplitude attenuation ratio as the ordinate can be directly generated according to the amplitude attenuation ratios corresponding to each frequency; or the amplitude attenuation ratios corresponding to each frequency can be converted into gain (unit: decibel (dB)), and an amplitude Bode plot with the frequency as the abscissa and the gain as the ordinate can be generated, as Figure 5 shown.

[0128] In the embodiment of the present application, the frequency response test result may include at least one of the amplitude attenuation ratios at various frequencies and the amplitude Bode plot.

[0129] In the embodiment of the present application, the frequency of the second control signal changes from the first preset frequency to the second preset frequency according to a preset step size, so as to cover the entire frequency band of the actual operation of the rear wheel steering gear assembly, and the actual peak displacement and the actual valley displacement at each frequency can be obtained. Combining with the amplitude of the second control signal, the amplitude attenuation ratio at each frequency can be calculated to reflect the amplitude attenuation degree of the actual displacement relative to the command displacement, so as to test whether the amplitude attenuation ratio of the rear wheel steering gear assembly at each frequency meets the requirements; if the amplitude attenuation degree is too large, it may cause a large difference between the actual steering angle of the vehicle's rear wheels and the command steering angle, resulting in the inability of the vehicle's rear wheels to turn in place. Therefore, in the embodiment of the present application, by obtaining the amplitude attenuation ratios at various frequencies, it can be detected whether the rear wheel steering gear assembly can make the vehicle's rear wheels turn in place; in addition, the amplitude Bode plot is finally generated in the embodiment of the present application, which can visually display the amplitude attenuation degree at each frequency, so as to quickly identify the frequency bands that do not meet the requirements and guide the optimization of the rear wheel steering gear assembly to make it meet the driving requirements.

[0130] In some embodiments, the frequency of the second control signal changes from a first preset frequency to a second preset frequency in a preset step size; Determine the frequency response test result according to the second displacement information, including: Obtain the actual peak time at each frequency according to the second displacement information; Obtain the command peak time at each frequency according to the second control signal; Determine the phase difference at each frequency according to the actual peak time at each frequency, the command peak time at each frequency, and each frequency; Generate a phase Bode plot according to the phase difference at each frequency.

[0131] Regarding the first preset frequency, the second preset frequency, and the preset step size, reference may be made to the relevant introduction in the foregoing embodiments, and details are not described herein again.

[0132] In the embodiments of the present application, the second actual displacement curve may be first low-pass filtered; then the Calculate Peaks function is used to pick peaks from the second actual displacement curve to obtain the actual peak time at each frequency (i.e., the abscissa value corresponding to the actual displacement reaching the peak at that frequency), and the second control signal is also correspondingly peak-picked to obtain the command peak time at each frequency (i.e., the abscissa value corresponding to the command displacement reaching the peak at that frequency). Each frequency corresponds to an actual peak time and a command peak time. It should be noted that the actual peak time and the command peak time corresponding to each frequency are corresponding, that is, if the first peak of the second actual displacement curve at that frequency is picked to obtain the actual peak time, then the first peak of the second control signal at that frequency is picked to obtain the command peak time; if the second peak of the second actual displacement curve at that frequency is picked to obtain the actual peak time, then the second peak of the second control signal at that frequency is picked to obtain the command peak time; and so on.

[0133] For each frequency, subtract the command peak time at that frequency from the actual peak time at that frequency to obtain the time difference at that frequency, and multiply the time difference at that frequency by that frequency and then by 2π to obtain the phase difference at that frequency. The phase differences at each frequency can reflect the delay angles between the actual displacement and the command displacement at each frequency.

[0134] It should be noted that the actual trough time and the command trough time at each frequency may also be obtained, and then the phase difference at each frequency is determined according to the actual trough time at each frequency, the command trough time at each frequency, and each frequency.

[0135] According to the phase difference at each frequency, the Generate Numeric function can be used to set a curve with M3 points, and the corresponding result is the phase difference. A phase Bode plot is generated. As Figure 6 shown, the abscissa is the frequency, and the ordinate is the phase difference or phase (unit: degree / deg).

[0136] In the embodiment of the present application, the frequency response test result may include at least one of the phase difference at each frequency and the phase Bode plot.

[0137] In the embodiment of the present application, the frequency of the second control signal changes from the first preset frequency to the second preset frequency according to a preset step size, so as to cover the entire frequency band of the actual operation of the rear wheel steering gear assembly, obtain the actual peak time and the command peak time at each frequency, and combine each frequency to calculate the phase difference at each frequency to reflect the phase delay degree of the actual displacement relative to the command displacement, so as to test whether the phase delay degree of the rear wheel steering gear assembly at each frequency meets the requirements; too large phase delay may cause the actual steering angle of the vehicle's rear wheels to be out of sync with the command steering angle, affecting vehicle stability. Therefore, in the embodiment of the present application, by obtaining the phase difference at each frequency, it can be detected whether the rear wheel steering gear assembly can make the vehicle drive stably; in addition, the phase Bode plot is finally generated in the embodiment of the present application, which can intuitively display the phase delay degree at each frequency, so as to quickly identify the frequency bands that do not meet the requirements and guide the optimization of the rear wheel steering gear assembly.

[0138] In some possible implementation manners, determining the frequency response test result according to the second displacement information may include the process of generating the amplitude Bode plot and the process of generating the phase Bode plot described above. That is, the frequency response test result may include at least one of the amplitude attenuation ratio at each frequency and the amplitude Bode plot, and at least one of the phase difference at each frequency and the phase Bode plot. For example, the frequency response test result may include the amplitude attenuation ratio at each frequency and the phase difference at each frequency; or, the frequency response test result may include the amplitude Bode plot and the phase Bode plot.

[0139] The amplitude reflects the intensity or magnitude of fluctuations, signals or systems; the frequency determines the vibration speed of the waveform, and the phase reflects the vibration state of the waveform at a certain moment. For waveforms with different frequencies, the phase difference will change over time. In the embodiment of the present application, combining the amplitude and the phase difference can comprehensively reflect the frequency response test result.

[0140] In some embodiments, the rear wheel steering gear test system further includes a baffle located on the rack, a load sensor for detecting the load force provided by the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear wheel steering gear assembly through the communication and power supply device; The baffle plate cooperates with the displacement sensor to detect the displacement information of the rack.

[0141] For the detailed description of the embodiments of the present application, reference can be made to the relevant descriptions in the aforementioned rear wheel steering gear test system, and details will not be repeated here.

[0142] In the embodiments of the present application, through the cooperation of the baffle plate and the displacement sensor, the problem of large displacement detection errors caused by some clearances of the test bench can be avoided, and the displacement detection accuracy can be improved; through the load sensor, the magnitude of the load force provided by the hysteresis brake can be fed back in real time, avoiding test errors caused by load force fluctuations; through the communication and power supply device, data interaction and power supply between the control device and the rear wheel steering gear assembly can be realized to meet the test requirements.

[0143] In the embodiments of the present application, through the above-mentioned rear wheel steering gear test system and rear wheel steering gear test method, the linear response speed and response speeds at different frequencies of the rear wheel steering gear assembly can be accurately measured. Using the hysteresis brake as the load providing device makes up for the lack of test methods and test systems for the rear wheel steering gear assembly, and it is simple to operate, low in cost, and easy to build; based on accurate test results, the rear wheel steering gear assembly can be optimized to improve the user driving experience.

[0144] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0145] Figure 7 It is a schematic structural diagram of a rear wheel steering gear test device 700 provided by an embodiment of the present application. The rear wheel steering gear test device 700 is applied to a rear wheel steering gear test system. The test system includes a hysteresis brake that provides a load force to the rear wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear wheel steering gear assembly, and a control device connected to the hysteresis brake, the displacement sensor, and the rear wheel steering gear assembly; as Figure 7 shown, the rear wheel steering gear test device 700 provided in this embodiment may include: a step response test module 701 and a frequency response test module 702.

[0146] Among them, the step response test module 701 is used to obtain the first displacement information of the rack when performing a step response test on the rear wheel steering gear assembly, and determine the step response test result according to the first displacement information; when performing the step response test, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear wheel steering gear assembly; A frequency response test module 702 is used to obtain second displacement information of a rack during a frequency response test on a rear wheel steering gear assembly, and determine a frequency response test result based on the second displacement information; during the frequency response test, a hysteresis brake provides a second load force, and a control device issues a second control signal to the rear wheel steering gear assembly.

[0147] In a possible implementation manner, in the step response test module 701, determining a step response test result based on the first displacement information includes: Based on the first displacement information, obtain the maximum actual displacement, the steady-state actual displacement value, the starting time of the actual displacement, the first time when the actual displacement first reaches the first preset percentage of the steady-state actual displacement value, and the second time when the actual displacement first reaches the second preset percentage of the steady-state actual displacement value during the step response test; the first preset percentage is less than the second preset percentage; Based on the first control signal, obtain the steady-state command displacement value, the third time when the command displacement first reaches the first preset percentage of the steady-state command displacement value, and the fourth time when the command displacement first reaches the second preset percentage of the steady-state command displacement value during the step response test; Obtain the input time of the first control signal to the rear wheel steering gear assembly; Based on the starting time of the actual displacement, the first time, the second time, the maximum actual displacement, the steady-state actual displacement value, the third time, the fourth time, the input time, and the steady-state command displacement value, determine the step response test result.

[0148] In a possible implementation manner, in the step response test module 701, determining a step response test result based on the starting time of the actual displacement, the first time, the second time, the maximum actual displacement, the steady-state actual displacement value, the third time, the fourth time, the input time, and the steady-state command displacement value includes: Based on the starting time of the actual displacement and the input time, determine the dead time of the rear wheel steering gear assembly; Based on the first time and the third time, determine the response time of the rear wheel steering gear assembly; Based on the second time and the fourth time, determine the execution time of the rear wheel steering gear assembly; Based on the maximum actual displacement and the steady-state command displacement value, determine the overshoot of the rear wheel steering gear assembly; Based on the steady-state actual displacement value and the steady-state command displacement value, determine the steady-state error of the rear wheel steering gear assembly.

[0149] In a possible implementation manner, the frequency of the second control signal changes from a first preset frequency to a second preset frequency in accordance with a preset step size; In the frequency response test module 702, according to the second displacement information, determine the frequency response test result, including: According to the second displacement information, obtain the actual peak displacement and the actual valley displacement at each frequency; Obtain the amplitude of the second control signal; According to the amplitude of the second control signal and the actual peak displacement and the actual valley displacement at each frequency, determine the amplitude attenuation ratio at each frequency; Generate an amplitude Bode plot according to the amplitude attenuation ratio at each frequency.

[0150] In a possible implementation manner, the frequency of the second control signal changes from a first preset frequency to a second preset frequency according to a preset step size; In the frequency response test module 702, according to the second displacement information, determine the frequency response test result, including: According to the second displacement information, obtain the actual peak time at each frequency; According to the second control signal, obtain the commanded peak time at each frequency; According to the actual peak time at each frequency, the commanded peak time at each frequency, and each frequency, determine the phase difference at each frequency; Generate a phase Bode plot according to the phase difference at each frequency.

[0151] In a possible implementation manner, the first control signal is a square wave control signal, and the second control signal is a sine wave control signal; The first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear wheel steering gear assembly can withstand; the second load force is less than the first load force.

[0152] In a possible implementation manner, the rear wheel steering gear test system further includes a baffle located on the rack, a load sensor for detecting the load force provided by the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear wheel steering gear assembly through the communication and power supply device; The baffle and the displacement sensor cooperate to detect the displacement information of the rack.

[0153] It should be noted that for the information interaction, execution process, etc. between the above devices / units, since they are based on the same concept as the method embodiments of the present application, their specific functions and the technical effects brought about can be specifically referred to in the method embodiment part, and will not be elaborated here.

[0154] Figure 8 It is a schematic structural diagram of a control device provided by an embodiment of the present application. As Figure 8As shown, the control device 800 of this embodiment includes: a processor 810 and a memory 820. A computer program 821 that can run on the processor 810 is stored in the memory 820. When the processor 810 executes the computer program 821, the steps in any of the above method embodiments are implemented, such as Figure 2 the steps 201 to 202 shown. Alternatively, when the processor 810 executes the computer program 821, the functions of each module / unit in the above device embodiments are implemented, such as Figure 7 the functions of the modules shown.

[0155] Exemplarily, the computer program 821 can be divided into one or more modules / units. One or more modules / units are stored in the memory 820 and executed by the processor 810 to complete this application. The one or more modules / units can be a series of computer program instruction segments capable of completing specific functions, and these instruction segments are used to describe the execution process of the computer program 821 in the control device 800.

[0156] Those skilled in the art can understand that Figure 8 this is merely an example of a control device and does not constitute a limitation on the control device. It may include more or fewer components than shown, or combine certain components, or different components, such as input / output devices, network access devices, buses, etc.

[0157] The processor 810 can be a central processing unit (CPU), or can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0158] The memory 820 can be an internal storage unit of the control device, such as the hard disk or memory of the control device, or an external storage device of the control device, such as a plug-in hard disk equipped on the control device, a SmartMedia Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. The above-mentioned memory 820 can also include both the internal storage unit of the control device and the external storage device. The above-mentioned memory 820 is used to store computer programs and other programs and data required by the control device. The memory 820 can also be used to temporarily store the data that has been output or will be output.

[0159] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above-mentioned functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiment and will not be elaborated here.

[0160] Corresponding to the above control device, an embodiment of the present application further provides a rear-wheel steering gear test system, including a hysteresis brake that provides a load force to the rear-wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear-wheel steering gear assembly, and the control device as described above; The hysteresis brake, the displacement sensor, and the rear-wheel steering gear assembly are all connected to the control device.

[0161] In a possible implementation manner, the rear-wheel steering gear test system further includes a baffle located on the rack, a load sensor for detecting the load force of the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear-wheel steering gear assembly through the communication and power supply device; The baffle and the displacement sensor cooperate to detect the displacement information of the rack.

[0162] For the detailed description of the rear-wheel steering gear test system, reference can be made to the relevant description in the foregoing embodiment and will not be elaborated here.

[0163] An embodiment of the present application further provides a computer-readable storage medium storing a computer program, which when executed by a processor implements any of the above-mentioned rear-wheel steering gear test methods.

[0164] An embodiment of the present application further provides a computer program product, including a computer program, which when executed by a processor implements any of the above-mentioned rear-wheel steering gear test methods.

[0165] In the above embodiments, the descriptions of the various embodiments have their own emphases. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0166] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0167] In the embodiments provided by the present invention, it should be understood that the disclosed device / control device and method can be implemented in other ways. For example, the device / control device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0168] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0169] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0170] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, it can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0171] The above-described embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for testing a rear-wheel steering gear, characterized in that, Applied to a rear-wheel steering gear test system, the test system includes a hysteresis brake that provides a load force to the rear-wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear-wheel steering gear assembly, and a control device connected to the hysteresis brake, the displacement sensor, and the rear-wheel steering gear assembly; the method includes: Obtain the first displacement information of the rack during a step response test on the rear-wheel steering gear assembly, and determine the step response test result based on the first displacement information; during the step response test, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear-wheel steering gear assembly; Obtain the second displacement information of the rack during a frequency response test on the rear-wheel steering gear assembly, and determine the frequency response test result based on the second displacement information; during the frequency response test, the hysteresis brake provides a second load force, and the control device issues a second control signal to the rear-wheel steering gear assembly.

2. The rear-wheel steering gear test method according to claim 1, characterized in that The determining the step response test result based on the first displacement information includes: Based on the first displacement information, obtain the maximum actual displacement, the steady-state actual displacement, the starting time of the actual displacement, the first time when the actual displacement first reaches the first preset percentage of the steady-state actual displacement, and the second time when the actual displacement first reaches the second preset percentage of the steady-state actual displacement during the step response test; the first preset percentage is less than the second preset percentage; Based on the first control signal, obtain the steady-state command displacement, the third time when the command displacement first reaches the first preset percentage of the steady-state command displacement, and the fourth time when the command displacement first reaches the second preset percentage of the steady-state command displacement during the step response test; Obtain the input time of the first control signal to the rear-wheel steering gear assembly; Determine the step response test result based on the starting time of the actual displacement, the first time, the second time, the maximum actual displacement, the steady-state actual displacement, the third time, the fourth time, the input time, and the steady-state command displacement.

3. The rear-wheel steering gear test method according to claim 2, characterized in that The determining the step response test result based on the starting time of the actual displacement, the first time, the second time, the maximum actual displacement, the steady-state actual displacement, the third time, the fourth time, the input time, and the steady-state command displacement includes: Determine the dead time of the rear-wheel steering gear assembly based on the starting time of the actual displacement and the input time; Determine the response time of the rear-wheel steering gear assembly based on the first time and the third time; Determine the execution time of the rear-wheel steering gear assembly based on the second time and the fourth time; Determine the overshoot of the rear-wheel steering gear assembly based on the maximum actual displacement and the steady-state command displacement; Determine the steady-state error of the rear-wheel steering gear assembly based on the steady-state actual displacement and the steady-state command displacement.

4. The rear wheel steering gear test method according to claim 1, characterized in that The frequency of the second control signal changes from a first preset frequency to a second preset frequency in a preset step size; Determining the frequency response test result according to the second displacement information includes: Obtaining the actual peak displacement and the actual valley displacement at each frequency according to the second displacement information; Obtaining the amplitude of the second control signal; Determining the amplitude attenuation ratio at each frequency according to the amplitude of the second control signal and the actual peak displacement and the actual valley displacement at each frequency; Generating an amplitude Bode plot according to the amplitude attenuation ratio at each frequency.

5. The rear-wheel steering gear test method according to claim 1, characterized in that The frequency of the second control signal changes from a first preset frequency to a second preset frequency in a preset step; Determining the frequency response test result according to the second displacement information includes: Obtaining the actual peak time at each frequency according to the second displacement information; Obtaining the commanded peak time at each frequency according to the second control signal; Determining the phase difference at each frequency according to the actual peak time at each frequency, the commanded peak time at each frequency, and each frequency; Generating a phase Bode plot according to the phase difference at each frequency.

6. The rear-wheel steering gear test method according to any one of claims 1 to 5, characterized in that, The first control signal is a square wave control signal, and the second control signal is a sine wave control signal; The first load force is the maximum load force that the hysteresis brake can provide or the maximum load force that the rear wheel steering gear assembly can withstand; the second load force is less than the first load force.

7. The rear-wheel steering gear test method according to any one of claims 1 to 5, characterized in that, The rear wheel steering gear test system further includes a baffle located on the rack, a load sensor for detecting the load force provided by the hysteresis brake, and a communication and power supply device; The load sensor is connected to the control device, and the control device is connected to the rear wheel steering gear assembly through the communication and power supply device; The baffle and the displacement sensor cooperate to detect the displacement information of the rack.

8. A rear-wheel steering gear testing device, characterized in that, Applied to a rear wheel steering gear test system, the test system includes a hysteresis brake that provides a load force to the rear wheel steering gear assembly, a displacement sensor that detects the displacement information of the rack on the rear wheel steering gear assembly, and a control device connected to the hysteresis brake, the displacement sensor, and the rear wheel steering gear assembly; The rear wheel steering gear test device includes: A step response test module, configured to obtain the first displacement information of the rack when performing a step response test on the rear wheel steering gear assembly, and determine a step response test result according to the first displacement information; when performing a step response test, the hysteresis brake provides a first load force, and the control device issues a first control signal to the rear wheel steering gear assembly; A frequency response test module, configured to obtain the second displacement information of the rack when performing a frequency response test on the rear wheel steering gear assembly, and determine a frequency response test result according to the second displacement information; when performing a frequency response test, the hysteresis brake provides a second load force, and the control device issues a second control signal to the rear wheel steering gear assembly.

9. A control device, characterized in that, It includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the rear wheel steering gear test method according to any one of claims 1 to 7.

10. A rear-wheel steering gear test system, characterized in that, A hysteresis brake that provides a load force to the rear wheel steering gear assembly, a displacement sensor that detects displacement information of a rack on the rear wheel steering gear assembly, and a control device as claimed in claim 9; The hysteresis brake, the displacement sensor, and the rear wheel steering gear assembly are all connected to the control device.

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