Vehicle wheel speed signal simulation method and vehicle test method

Abstract

The invention relates to the technical field of automobile electronic testing, and provides a vehicle wheel speed signal simulation method and a vehicle testing method. The vehicle wheel speed signal simulation method comprises the steps of obtaining signal characteristics of a wheel speed signal corresponding to a preset test wheel speed, wherein the wheel speed signal is a signal output when a wheel speed sensor is assumed to detect the preset test wheel speed; controlling a wheel speed signal simulator to generate and output a simulated wheel speed signal of the signal characteristic to a brake system for analysis; the preset test wheel speed is the test wheel speed required in the function test of the brake system. According to the vehicle wheel speed signal simulation method, the mode of simulating and generating the wheel speed signal is adopted to replace the actual use of a wheel speed sensor in the function test of a braking system. Therefore, most typical working conditions and extreme working conditions in the vehicle driving process can be covered to improve the working condition coverage rate, the test safety can be improved, and the probability of accidents caused by unreliable functions of a brake system during real vehicle test is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile electronic testing, in particular to a vehicle wheel speed signal simulation method and a vehicle testing method. BACKGROUND

[0002] In the vehicle production and development process, the function test of the brake system needs to be performed. The brake system is used to analyze the wheel speed signal output by the wheel speed sensor, to determine whether the wheel is slipping, locked or dynamically unstable, and to adjust the brake force distribution accordingly, so as to ensure the braking performance and safety of the vehicle.

[0003] In the related art, the function test of the brake system usually needs the wheel to be in the actual driving condition, and the wheel speed signal output by the wheel speed sensor is output to the brake system. However, this method is difficult to realize the function test under extreme conditions, resulting in low coverage of working conditions and difficulty in meeting the test requirements. Moreover, the brake system is one of the most important safety structures in the vehicle, and there is uncertainty in the reliability of the brake system during the research and development stage. At this time, directly testing the brake system on the actual vehicle also has a high safety risk. SUMMARY

[0004] Therefore, the present application aims to provide a vehicle wheel speed signal simulation method to improve the coverage of working conditions and improve the safety of testing.

[0005] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows: A vehicle wheel speed signal simulation method, the simulation method comprising: obtaining the signal characteristics of the wheel speed signal corresponding to the preset test wheel speed, wherein the wheel speed signal is the signal that the wheel speed sensor should output when detecting the preset test wheel speed; using the signal characteristics as reference signal characteristics, controlling the wheel speed signal simulator to generate an analog wheel speed signal with the same signal characteristics as the reference signal characteristics, and outputting the analog wheel speed signal to the brake system of the vehicle, so that the brake system analyzes the analog wheel speed signal to obtain the wheel speed of the vehicle and performs a function test; wherein the preset test wheel speed is the wheel test speed required in the function test of the brake system of the vehicle.

[0006] Further, the wheel speed signal output by the wheel speed sensor is a pulse signal, and the signal characteristics of the wheel speed signal include the pulse period and the pulse format. The signal characteristics of the wheel speed signal output by the wheel speed sensor when detecting the preset test wheel speed include: determining the pulse format of the wheel speed signal according to the preset test wheel speed and the signal protocol corresponding to the wheel speed sensor; acquire a pulse period of a wheel speed signal output by the wheel speed sensor under the assumption that the wheel speed sensor detects the preset test wheel speed.

[0007] Further, the acquiring of the pulse period of the wheel speed signal that should be output by the wheel speed sensor under the assumption that the wheel speed sensor detects the preset test wheel speed comprises: acquiring a wheel radius of the wheel; calculating the pulse period of the wheel speed signal through a preset relationship according to the number-of-teeth-to-pulse-number ratio of the wheel speed sensor, the number of magnetic poles of the gear magnetic ring of the wheel speed sensor, and the wheel radius; The number-of-teeth-to-pulse-number ratio represents the ratio between the number of pulses generated by the monitoring component of the wheel speed sensor and the number of magnetic poles of the gear magnetic ring that pass through the monitoring component.

[0008] Further, the preset relationship is:

[0009] wherein T is the pulse period of the pulse signal, v is the preset test wheel speed; r is the wheel radius, N is the number of magnetic poles; and k is the number-of-teeth-to-pulse-number ratio.

[0010] Further, the wheel speed signal simulator comprises a plurality of pulse signal generating circuits, each of which has a corresponding preset pulse amplitude, and the control wheel speed signal simulator generates an analog wheel speed signal with the same signal characteristics as the reference signal characteristics, comprising: controlling at least two of the pulse signal generating circuits to work and output corresponding electrical signals based on the pulse format and pulse period corresponding to the reference signal characteristics and the preset pulse amplitude corresponding to each of the pulse signal generating circuits; superimposing the electrical signals output by each of the pulse signal generating circuits and generating the analog wheel speed signal.

[0011] Further, the pulse format comprises a high-level corresponding amplitude, a low-level corresponding amplitude, and a pulse width, and the controlling of each of the pulse signal generating circuits to work and output corresponding electrical signals based on the pulse format and pulse period corresponding to the reference signal characteristics and the preset pulse amplitude corresponding to each of the pulse signal generating circuits comprises: determining a first target signal generating circuit from each of the pulse signal generating circuits in which the preset pulse amplitude is the same as the low-level corresponding amplitude according to the low-level corresponding amplitude and the preset pulse amplitude corresponding to each of the pulse signal generating circuits; determining, from the pulse signal generation circuits, a second target signal generation circuit having the same pulse amplitude as the preset pulse amplitude according to a difference between the high level corresponding amplitude and the low level corresponding amplitude; controlling the first target signal generation circuit to continuously output an electrical signal satisfying the low level corresponding amplitude, and controlling the second target signal generation circuit to output an electrical signal varying according to the pulse period of the reference signal feature, and the pulse width of the electrical signal being the same as the pulse width in the reference signal feature.

[0012] Further, each of the pulse signal generation circuits comprises a switching unit and a first resistor; One end of the first resistor is connected to the positive pole of a first power supply, the other end of the first resistor is connected to one end of the switching unit, and the other end of the switching unit is connected to the negative pole of the first power supply. The switching unit can be in a conducting or off state under control, and the negative pole of the first power supply outputs the electrical signal.

[0013] Further, the switching unit comprises an optical coupler, a second resistor and a switch tube. The collector of the optical coupler is connected to the end of the first resistor not connected to the first power supply, and the emitter of the optical coupler is connected to the negative pole of the first power supply for outputting a corresponding electrical signal. One end of the second resistor is connected to a second power supply, and the other end of the second resistor is connected to the anode of the optical coupler. The switch tube comprises a control end, a current input end and a current output end, the current input end of the switch tube is connected to the cathode of the optical coupler, and the current output end of the switch tube is grounded.

[0014] Compared with the related art, the present application has the following advantages: The vehicle wheel speed signal simulation method of the present application calculates the signal feature of the wheel speed signal that the wheel speed sensor should output, and controls the wheel speed signal simulator to simulate the generation of the wheel speed signal, thereby replacing the use of the actual wheel speed sensor in the functional test scene of the braking system. In this way, the vehicle braking system does not need to be actually placed in the corresponding test working condition, but the preset test wheel speed can be flexibly adjusted to adjust the reference signal feature, thereby realizing the simulation of the wheel speed signal.

[0015] In this way, for extreme working conditions, the preset test wheel speed can also be adjusted to achieve the extreme working conditions, for example, if the extreme working condition of "120km / h rapid deceleration to 0km / h" needs to be simulated, only the preset test wheel speed needs to be set, and the wheel speed signal simulator generates the simulated wheel speed signal according to the corresponding reference signal characteristics. For a large number of extreme scenarios, the test can be quickly realized by adjusting the preset test wheel speed, without the need to actually place the vehicle braking system in the real vehicle test working condition, which makes the test of the braking system cover most of the typical working conditions and extreme working conditions in the vehicle driving process, thereby improving the working condition coverage. And in the research and development stage, before it is determined whether the function of the braking system is reliable, the real vehicle test can be carried out first, and the simulated wheel speed signal is generated to the braking system, and the braking system performs corresponding calculation, so that the test is carried out in a simulated manner without the need for real vehicle test in the corresponding working condition, which can reduce the risk of safety accidents caused by abnormal function of the braking system during real vehicle test, thereby improving the test safety.

[0016] At the same time, since the application uses the simulated wheel speed signal to replace the actual wheel speed sensor in the functional test scene of the braking system, in the test, there is no need to additionally purchase, install and maintain the wheel speed sensor and supporting components, and the direct cost of hardware purchase and replacement is saved.

[0017] At the same time, the vehicle wheel speed signal simulation method of the application is simulated by the wheel speed signal simulator, which will not be disturbed by external environmental conditions like the actual wheel speed sensor, so that the wheel speed signal received by the braking system can remain stable and accurate, and the wheel speed calculation based on the simulated wheel speed signal can better reflect the real function level of the measured part, thereby avoiding test errors caused by environmental factors and improving the accuracy and reliability of the test results.

[0018] At the same time, through the vehicle wheel speed signal simulation method of the application, the test work of the control system is no longer simply dependent on the manual clicking of the upper computer panel by engineers to manufacture working condition tests, but can be decoupled from the human machine through advanced environmental equipment and related tools in a fully automated script manner. For example, for the test of the braking system, if the real vehicle environment test is carried out, it undoubtedly increases the workload of the engineers and reduces the work efficiency, and consumes the vehicle resources, and through the vehicle wheel speed signal simulation method of the application, the functional test of the braking system can be moved from the vehicle to the laboratory, and the environmental equipment including the wheel speed signal simulator is controlled by the program to realize the human-machine decoupled test, thereby improving the test efficiency and test convenience.

[0019] Another purpose of the application is to provide a vehicle test method for testing the function of the braking system of the vehicle, which comprises obtaining the simulated wheel speed signal meeting the preset test condition through the above-mentioned vehicle wheel speed signal simulation method. The analog wheel speed signal is output to the brake system, so that the brake system parses the analog wheel speed signal and performs corresponding function control, realizing function test of the brake system.

[0020] Further, the test method further includes that the brake system parses the analog wheel speed signal to obtain the wheel speed of the vehicle, and outputs the wheel speed.

[0021] The vehicle test method described in the present application replaces the use of an actual wheel speed sensor in the function test scenario of the brake system by controlling the wheel speed signal simulator to simulate the generation of a wheel speed signal. This can cover most typical and extreme conditions during vehicle driving, and can improve the coverage rate of working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings should not be construed as an inappropriate limitation on the present application. In the drawings: Figure 1 Flowchart of the vehicle wheel speed signal simulation method described in the embodiments of the present application; Figure 2 Flowchart of the calculation of signal characteristics in the vehicle wheel speed signal simulation method described in the embodiments of the present application; Figure 3 Schematic diagram showing the principle of the generation of a pulse signal by the wheel speed sensor described in the embodiments of the present application; Figure 4 Flowchart of the control of the generation of an analog wheel speed signal in the vehicle wheel speed signal simulation method described in the embodiments of the present application; Figure 5 Flowchart of the control of the operation of each pulse signal generation circuit in the vehicle wheel speed signal simulation method described in the embodiments of the present application; Figure 6 Circuit structure example diagram of one set of wheel speed simulation signal generation circuits in the wheel speed signal simulator described in the embodiments of the present application; Figure 7 Overall flowchart of the vehicle wheel speed signal simulation method described in the embodiments of the present application. DETAILED DESCRIPTION

[0023] In order to make the technical solutions of the present application and their advantages clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0025] In addition, in the description of the present application, it should be noted that if the terms indicating the orientation or position relationship such as "upper", "lower", "inner", "outer" and the like appear, they are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first", "second" and the like appear, they are also only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0026] In addition, in the description of the present application, unless otherwise explicitly limited, the terms "mounting", "connecting", "connection", "connector" should be understood broadly. For example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood in conjunction with the specific circumstances.

[0027] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0028] In the following, the present application will be specifically described through exemplary embodiments. However, it should be understood that the elements, structures and features in one embodiment can also be beneficially combined into other embodiments without further description.

[0029] The embodiment of the first aspect of the present application provides a wheel speed signal simulation method for simulating the wheel speed signal output by the wheel speed sensor when the wheel of the vehicle is at a preset test wheel speed, and replacing the wheel speed signal output by the wheel speed sensor. In this way, the vehicle's braking system does not need to actually put the wheel in the corresponding test working condition. This makes the test of the braking system control unit cover most of the typical and extreme working conditions during vehicle driving, thereby improving the working condition coverage rate.

[0030] In the related art, in the scenarios of vehicle production development, etc., the vehicle braking system (more specifically, the control unit of the vehicle braking system) needs to be tested. The control unit of the vehicle braking system is the control center of the vehicle braking system. In the process of vehicle driving, the wheel speed signal output by the wheel speed sensor of the vehicle wheel can be analyzed to determine the state of the vehicle wheel, such as judging whether the vehicle wheel is slipping, locked or dynamically unstable, etc., and then adjusting the brake force distribution according to the state of the vehicle wheel, thereby improving the braking performance and safety of the vehicle.

[0031] In the process of testing the vehicle braking system in the related art, the vehicle wheel configured with the wheel speed sensor is usually placed in the corresponding actual test scene, such as making the vehicle wheel drive at a set test wheel speed, and simulating different test conditions by constantly adjusting the set test wheel speed of the vehicle wheel. The wheel speed sensor actually measures the wheel speed of the vehicle wheel and outputs the corresponding wheel speed signal to the vehicle braking system.

[0032] The vehicle braking system analyzes the wheel state according to the wheel speed signal output by the wheel speed sensor to determine whether the vehicle wheel is slipping, etc., so as to realize the adjustment of the brake force distribution.

[0033] However, the test of the vehicle braking system in the related art relies on the real wheel speed sensor, which makes the cost of the test equipment higher.

[0034] And the real wheel speed sensor is sensitive to environmental conditions, such as temperature, humidity and vibration, which will affect the wheel speed signal output by the wheel speed sensor, causing the vehicle braking system to misjudge the state of the vehicle wheel and affect the accuracy of the test.

[0035] Furthermore, the test method in the related art is also difficult to simulate extreme conditions, such as sudden acceleration or sudden deceleration, etc. That is, the test method in the related art is difficult to cover all driving conditions of the vehicle, and the condition coverage rate is low.

[0036] Furthermore, the braking system is one of the most important safety structures in the vehicle, and there is a great safety risk in real vehicle testing during the research and development stage without verified reliability.

[0037] Therefore, in order to overcome the deficiencies in the related art, the vehicle wheel speed signal simulation method of the embodiment can simulate the wheel speed signal output by the wheel speed sensor during testing and be used in the functional test of the vehicle braking system. In the embodiment, the simulation of the wheel speed signal of one of the vehicle wheels is taken as an example for description. The simulation of the wheel speed signal of other vehicle wheels can be referred to the embodiment, which will not be described here.

[0038] In combination with Figure 1The vehicle wheel speed signal simulation method according to the embodiment includes the following steps S110-S120.

[0039] In step S110, a signal feature of a wheel speed signal corresponding to a preset test wheel speed is acquired.

[0040] The wheel speed signal is a signal that a wheel speed sensor should output when detecting the preset test wheel speed.

[0041] The preset test wheel speed is a test wheel speed of a wheel required in a function test of a braking system of a vehicle.

[0042] Specifically, the preset test wheel speed is a wheel speed of a wheel that is preset and used for testing the function of the braking system of the vehicle. For example, if the preset test wheel speed is 10 km / h, the preset test wheel speed is 10 km / h.

[0043] A real wheel speed sensor used in the related art is usually designed in a magneto-electric or Hall effect manner, and generates a PWM (Pulse Width Modulation Protocol) signal of a specific duty cycle by detecting a change in a magnetic field when a wheel rotates, i.e., a pulse signal of a specific duty cycle. The wheel speed signal output by the wheel speed sensor is a pulse signal. It should be noted that in the vehicle wheel speed signal simulation method according to the embodiment, the real wheel speed sensor is not actually used when testing the braking system of the vehicle, and no corresponding components need to be provided, and only the wheel speed signal output by the wheel speed sensor needs to be simulated according to the preset test wheel speed and other information.

[0044] In step S110, the signal feature of the wheel speed signal includes a pulse period and a pulse format of the pulse signal. The pulse format can be a low level corresponding to an amplitude (e.g., 7 mA) and a high level corresponding to an amplitude (e.g., 14 mA).

[0045] It is assumed that the vehicle is at the preset test wheel speed, and it is assumed that a wheel speed sensor is configured on the wheel. The wheel speed sensor should output a wheel speed signal corresponding to the preset test wheel speed. In step S110, the signal feature of the wheel speed signal that the wheel speed sensor should output can be calculated by the logic and principle of generation of the pulse signal of the wheel speed sensor to acquire the signal feature, and the wheel speed sensor is not actually configured.

[0046] In step S120, the signal feature is used as a reference signal feature, a wheel speed signal simulator is controlled to generate an analog wheel speed signal with the same signal feature as the reference signal feature, and the analog wheel speed signal is output.

[0047] Specifically, one vehicle often includes multiple wheels, and each wheel often corresponds to a preset test wheel speed. The wheel speed signal simulator can generate a corresponding simulated wheel speed signal for each wheel.

[0048] More specifically, the wheel speed signal simulator can include wheel speed signal simulation circuit corresponding to each wheel, that is, each wheel corresponds to a set of wheel speed signal simulation circuit, and in the case of a vehicle with four wheels, the wheel speed signal simulator can include four sets of wheel speed signal simulation circuit, wherein each set of wheel speed signal simulation circuit is used to generate a corresponding simulated wheel speed signal for the corresponding wheel. Taking one of the wheels as an example, using the wheel speed signal simulation circuit corresponding to the wheel in the wheel speed signal simulator and the reference signal feature, a simulated wheel speed signal with the same signal feature as the reference signal feature (for example, a pulse current with a high level of 14mA and a low level of 7mA with the same duty cycle) is generated. In this way, the corresponding simulated wheel speed signal can be generated without a real wheel speed sensor.

[0049] Continuing to take the wheel as an example, after generating the simulated wheel speed signal, the simulated wheel speed signal is output to the brake system, and after being analyzed by the brake system, it is used for functional testing. For example, after the brake system receives the simulated wheel speed signal, it can determine the wheel speed of the wheel by analyzing the simulated wheel speed signal (under normal circumstances, the wheel speed of the vehicle analyzed is equal to or approximately equal to the preset test wheel speed). Then, according to the wheel speed of the wheel (and the wheel speed determined at the last time), the state of the wheel can be determined to judge whether the wheel has abnormal states such as skidding, locking or dynamic instability, and the brake force distribution strategy is adjusted according to the preset brake control logic. If the brake system can output correct brake force distribution adjustment instructions in time under the preset test condition, it proves that the dynamic brake adjustment function of the brake system is good. Similarly, if the brake system cannot output correct brake force distribution adjustment instructions in time, it proves that the dynamic brake adjustment function of the brake system is abnormal, thereby completing the test of the brake system of the vehicle.

[0050] It is worth noting that in the vehicle wheel speed signal simulation method of the embodiment, not only is it not necessary to actually set a wheel speed sensor, but also in the brake test, an actual wheel can not be configured, only the preset test wheel speed is preset in the brake test, and the corresponding simulated wheel speed signal is generated by the wheel speed signal simulator to the brake system, so that the functional test of the brake system can be performed.

[0051] Thus, the vehicle wheel speed signal simulation method of the embodiment replaces the use of the actual wheel speed sensor in the functional test scene of the brake system by calculating the signal characteristics of the wheel speed signal that the wheel speed sensor should output and controlling the way in which the wheel speed signal simulator simulates the generation of the wheel speed signal. In this way, the vehicle brake system does not need to be actually placed in the corresponding test working condition, but the preset test wheel speed can be flexibly adjusted to adjust the reference signal characteristics, thereby realizing the simulation of the wheel speed signal.

[0052] In this way, the extreme working condition can also be realized by adjusting the preset test wheel speed, for example, if the extreme working condition of "120km / h rapid deceleration to 0km / h" needs to be simulated, only the preset test wheel speed needs to be set, and the wheel speed signal simulator generates the simulated wheel speed signal according to the corresponding reference signal characteristics. For a large number of extreme scenes, the preset test wheel speed can be quickly adjusted to realize the simulation without actually placing the vehicle brake system in the real vehicle test working condition. This makes the test of the brake system cover most of the typical working conditions and extreme working conditions in the vehicle driving process, thereby improving the working condition coverage rate. Moreover, before ensuring the reliability of the brake system function, the real vehicle test can be performed, but the test can be performed in a simulated manner, which can also reduce the risk of safety accidents caused by abnormal brake system function during the real vehicle test, thereby improving the test safety.

[0053] At the same time, since the embodiment replaces the use of the actual wheel speed sensor in the functional test scene of the brake system with the simulated wheel speed signal, the wheel speed sensor and the supporting components do not need to be additionally purchased, installed and maintained in the test, thereby saving the direct cost of hardware purchase and replacement.

[0054] At the same time, the vehicle wheel speed signal simulation method of the embodiment is the wheel speed signal simulated by the wheel speed signal simulator, which is not disturbed by the external environmental conditions like the actual wheel speed sensor. In this way, the wheel speed signal received by the brake system can remain stable and accurate, so that the wheel speed calculation based on the simulated wheel speed signal can better reflect the real function level of the measured part, thereby avoiding the test error caused by the environmental factors and improving the accuracy and reliability of the test results.

[0055] Meanwhile, by the vehicle wheel speed signal simulation method, the test work of the control system of the vehicle is no longer simply dependent on the manual clicking of the panel of the host computer by the engineers to make the test, but can be decoupled from the human machine test by the advanced environment equipment and the related tools through the full-automatic script. For example, for the test of the braking system, if the test is in the real environment of the vehicle, the workload of the engineers is increased, the work efficiency is reduced, and the vehicle resources are wasted. By the vehicle wheel speed signal simulation method, the test of the braking system can be moved from the vehicle to the laboratory, and the environment equipment including the wheel speed signal simulator is controlled by the program to realize the decoupled test of the human machine (for example, the program script automatically outputs the corresponding preset test speed to the wheel speed signal simulator, so that the wheel speed signal simulator generates the corresponding simulated wheel speed signal to the braking system according to the internal program logic for testing), thereby improving the test efficiency and the test convenience.

[0056] Continuing from Figure 1 , and in conjunction with Figure 2 , in some exemplary embodiments, in step S110, the signal characteristics of the wheel speed signal output by the wheel speed sensor when detecting the preset test wheel speed are acquired, which can include the following steps S111-S112.

[0057] In step S111, the pulse format of the wheel speed signal output by the wheel speed sensor at the preset test wheel speed is determined according to the preset test wheel speed and the signal protocol corresponding to the wheel speed sensor.

[0058] In step S112, the pulse period of the wheel speed signal that should be output by the wheel speed sensor under the assumption that the wheel speed sensor detects the preset test wheel speed is acquired.

[0059] Specifically, the real wheel speed sensor in the related art usually adopts a magneto or Hall effect design, and generates a pulse signal by detecting the change of the magnetic field when the wheel rotates. That is, the wheel speed signal output by the wheel speed sensor is a pulse signal. The pulse period (denoted by T) refers to the time interval between the rising edges (or falling edges) of two adjacent pulses in the pulse signal.

[0060] Referring to Figure 3 , Figure 3 shows the principle of generating a pulse signal by a real wheel speed sensor in the related art. The wheel speed sensor usually includes a monitoring component and a gear magnetic ring that rotates synchronously with the wheel. Taking a Hall type wheel speed sensor as an example, the monitoring component refers to the Hall device segment of the wheel speed sensor, and the gear magnetic ring is installed on the wheel. Each tooth of the gear magnetic ring corresponds to a magnetic pole, and as the wheel rotates, the gear magnetic ring rotates, and the magnetic poles (N poles and S poles are alternately distributed) on the surface of the gear magnetic ring periodically pass through the monitoring component.

[0061] The Hall element segment (monitoring component) converts physical signals into electrical signals by detecting magnetic field fluctuations caused by changes in magnetic poles, and finally generates continuous pulses. Each time a magnetic pole passes through the monitoring component, a corresponding number of pulses will be generated (generated in a fixed ratio, for example, two pulses will be generated for each magnetic pole (tooth) passed through).

[0062] The higher the wheel speed of the vehicle, the faster the wheel rotates, the higher the frequency at which the magnetic poles of the gear magnetic ring pass through the monitoring component, and the shorter the pulse period; conversely, the lower the wheel speed, the longer the pulse period. Thus, by using the preset test wheel speed and the pulse generation principle of the wheel speed sensor, the pulse period can be calculated.

[0063] Continue by Figures 1-3 As shown, in some exemplary embodiments, step S112 above, obtaining the pulse period T of the wheel speed signal that the wheel speed sensor should output when assuming the wheel speed sensor detects the preset test wheel speed, may specifically include: obtaining the wheel radius. The pulse period of the wheel speed signal is calculated using a preset formula based on the ratio of the number of pulses per tooth of the wheel speed sensor, the number of magnetic poles of the gear magnetic ring of the wheel speed sensor, and the wheel radius.

[0064] The tooth-to-pulse ratio (represented by k in this embodiment) represents the ratio between the number of pulses generated by the wheel speed sensor's monitoring component and the number of magnetic poles passing through the monitoring component. For example, when the wheel speed sensor's monitoring component generates two pulses for each magnetic pole (tooth), the tooth-to-pulse ratio k is 2. In this embodiment, the tooth-to-pulse ratio is pre-set based on the pulse generation principle of the actual wheel speed sensor that the braking system should be connected to.

[0065] The wheel radius (represented by r in this embodiment) is the distance from the center of the wheel to the outer edge of the tire, and the circumference of the wheel is equal to... The circumference of a wheel determines the distance it travels with each rotation.

[0066] The number of magnetic poles (represented by N in this embodiment) refers to the total number of magnetic poles evenly distributed on the gear magnetic ring (e.g., 48). The number of magnetic poles determines the number of magnetic pole changes that the monitoring component can detect for each revolution of the wheel.

[0067] By using the wheel radius, the number of magnetic poles, and the ratio of the number of pulses to the number of teeth, and applying the preset formula corresponding to the wheel speed sensor, the pulse period T of the wheel speed signal output by the wheel speed sensor at the preset test wheel speed can be obtained.

[0068] In some exemplary implementations, the predefined relation is: 。

[0069] Wherein, T is the pulse period of the pulse signal, v is the preset test wheel speed, for example, 10 km / h; r is the wheel radius, N is the number of magnetic poles; k is the number of tooth pulse ratio.

[0070] Specifically, The number of turns per unit time of the wheel is represented, and the number of turns per unit time multiplied by the number of magnetic poles N represents the number of magnetic poles passing through the monitoring component per second. The number of magnetic poles passing through the monitoring component per second multiplied by the number of tooth pulse ratio k obtains the number of pulses generated per second (i.e. pulse frequency f, unit Hz); The reciprocal of the pulse frequency f is the pulse period T. In this way, the pulse period can be obtained by using the preset relationship, so as to facilitate the subsequent simulation of the wheel speed signal.

[0071] For example, if v=10 km / h (converted to 2.778 m / s), r=0.383 m, N=48, and k=2, substitute the preset relationship, f=2.778 / (2×3.14×0.383)×48×2=27.7 Hz, that is, the pulse period T=1 / 27.7≈0.0361 s, that is, when the preset test wheel speed is 10 km / h, the parameter k=2, N=48, and r=0.383 m, the corresponding pulse period is about 36.1 ms.

[0072] In this way, the calculation of the pulse period is quantified by the preset relationship, rather than by empirical estimation, which can improve the accuracy of the calculation of the pulse period.

[0073] For the determination process of the pulse format of the wheel speed signal in the above step S111, specifically, the pulse format includes pulse width (abbreviated as pulse width). The current mainstream signal protocol of the wheel speed sensor is: ① standard protocol, ② PWM protocol, and ③ AK protocol. The signal protocol refers to the wheel speed signal transmission rule agreed between the wheel speed sensor and the braking system, including the generation method of the signal, the amplitude range, the time characteristics (period / pulse width), the data analysis logic, etc. It is the "common language" to ensure that the braking system of the vehicle can accurately identify the output signal of the wheel speed sensor.

[0074] Among them, the standard protocol is also called general pulse protocol, which only reflects the wheel speed through the pulse period (for example, the period is inversely proportional to the wheel speed), without clear amplitude division and direction recognition logic.

[0075] The PWM protocol refers to the combination of pulse width (pulse width) and pulse amplitude to simultaneously transmit wheel speed, rotation direction, signal validity, etc.

[0076] The AK (Anti-lock Brake System K-line Protocol) protocol refers to a bidirectional communication protocol based on a K-line (diagnostic communication line). In addition to transmitting wheel speed signals (pulse period + pulse width), the AK protocol also supports the vehicle's brake system sending diagnostic instructions (such as sensor fault detection and parameter calibration) to the wheel speed sensor.

[0077] In this embodiment, the PWM protocol (more specifically, the current-mode PWM pulse modulation protocol) is used as the corresponding signal protocol for the wheel speed sensor. Specifically, the current-mode PWM protocol distinguishes the rotation state of the wheel through the pulse width range (the width of the high-level pulse). For example, the current-mode PWM protocol includes five types of periodic waves: (1) When the vehicle speed v is 0 km / h, the periodic wave corresponds to a waveform with a pulse width (the duration of a single pulse, i.e., the duration of the high-level corresponding to a single pulse) ranging from 1232 us to 1440 us to 1656 us (where 1440 us is the reference pulse width, and the high-level duration of a single pulse ranges from 1232 microseconds to 1656 microseconds), and the interval between pulses ranges from 105 ms to 150 ms to 195 ms. At this time, the wheel speed obtained by the brake system based on the periodic wave is 0 km / h.

[0078] (2) When the wheel speed is relatively large, for example, the pulse frequency (calculated based on the wheel speed) f is greater than 117 Hz, and the wheel rotates in the clockwise (CW) direction, the periodic wave corresponds to a waveform with a pulse width ranging from 26 us to 90 us to 104 us (where 90 us is the reference pulse width, and the high-level duration of a single pulse ranges from 26 microseconds to 104 microseconds). The specific vehicle speed is determined based on the periodic wave. At this time, the brake system obtains the clockwise rotation of the wheel (the specific vehicle speed is identified and determined based on the pulse period) based on the periodic wave.

[0079] (3) When the pulse frequency f is greater than 117 Hz, and the wheel rotates in the counterclockwise (CCW) direction, the periodic wave corresponds to a waveform with a pulse width ranging from 153 us to 180 us to 207 us (where 180 us is the reference pulse width, and the high-level duration of a single pulse ranges from 153 microseconds to 207 microseconds). At this time, the brake system obtains the counterclockwise rotation of the wheel based on the periodic wave.

[0080] (4) When the pulse frequency f is less than 117 Hz and the wheel rotates in a clockwise direction, the periodic wave corresponds to a pulse width range of 306us-360us-414us (where 360us is the reference pulse width, and the high-level duration of a single pulse is between 306 microseconds and 414 microseconds). At this time, the braking system obtains that the wheel rotates in a clockwise direction according to the periodic wave.

[0081] (5) When the pulse frequency f is less than 117 Hz and the wheel rotates in an anticlockwise direction, the periodic wave corresponds to a pulse width range of 616us-720us-828us (where 720us is the reference pulse width, and the high-level duration of a single pulse is between 616 microseconds and 828 microseconds). At this time, the braking system obtains that the wheel rotates in a clockwise direction according to the periodic wave.

[0082] Thus, in step S111, the pulse format can be determined according to the preset test wheel speed and the signal protocol. For example, first, the preset test wheel speed is divided according to the pulse width range of the periodic wave, and then the pulse frequency f is calculated according to the pulse width range corresponding to the preset test wheel speed. After that, the pulse format corresponding to the preset test wheel speed is determined according to the rotation direction of the preset test wheel speed and the pulse frequency f corresponding to the preset test wheel speed. For example, if it belongs to the case that the pulse frequency is less than 117 Hz and the wheel rotates in an anticlockwise direction, the pulse format is the format of the pulse width range in the range of 616us-720us-828us.

[0083] Thus, through steps S111 and S112, the pulse format can be determined by applying the signal protocol, and then the pulse period can be calculated, so as to determine the high-level and low-level duration of the pulse signal in each pulse period (that is, to determine the duty cycle and high-low level amplitude), which together constitute the reference signal characteristics, so as to generate the analog wheel speed signal consistent with the real wheel speed sensor according to the reference signal characteristics, and lay the foundation for the function test of the braking system.

[0084] Figures 1-2 Figure 4 In some exemplary embodiments, in step S120, the control wheel speed signal simulator generates an analog wheel speed signal with the same signal characteristics as the reference signal characteristics, which can specifically include steps S121-S122.

[0085] ​​​The wheel speed signal simulator includes a plurality of pulse signal generating circuits, each of which has a preset pulse amplitude corresponding thereto. Specifically, each wheel speed signal simulation signal generating circuit included in the wheel speed signal simulator can include a plurality of pulse signal generating circuits, and more specifically, taking the wheel speed signal simulation signal generating circuit corresponding to one wheel as an example, the pulse signal generating circuits corresponding to other wheel speed signal simulation signal generating circuits can be referred to for reference, and will not be described herein.

[0086] The wheel speed signal simulation signal generating circuit includes a plurality of pulse signal generating circuits, each of which has a preset pulse amplitude corresponding thereto. For example, the wheel speed signal simulation signal generating circuit includes a first pulse signal generating circuit, a second pulse signal generating circuit, and a third pulse signal generating circuit. The preset pulse amplitude corresponding to the first pulse signal generating circuit is 7 mA (i.e., the first pulse signal generating circuit alone will generate a current signal with an amplitude of 7 mA), the preset pulse amplitude corresponding to the second pulse signal generating circuit is 7 mA (i.e., the second pulse signal generating circuit alone will generate a current signal with an amplitude of 7 mA), and the preset pulse amplitude corresponding to the third pulse signal generating circuit is 14 mA (i.e., the third pulse signal generating circuit alone will generate a current signal with an amplitude of 14 mA).

[0087] The first pulse signal generating circuit, the second pulse signal generating circuit, and the third pulse signal generating circuit are connected in parallel. For example, when the first pulse signal generating circuit and the second pulse signal generating circuit are both working, and the third pulse signal generating circuit is not working, the first pulse signal generating circuit outputs a current of 7 mA, the second pulse signal generating circuit outputs a current of 7 mA, and the third pulse signal generating circuit outputs a current of 0 mA. Since the three are connected in parallel, the currents output by the pulse signal generating circuits are collected and output as a current of 14 mA.

[0088] In step S121, based on the pulse format and the pulse period corresponding to the reference signal feature, and the preset pulse amplitude corresponding to each pulse signal generating circuit, at least two pulse signal generating circuits are controlled to work and output corresponding electrical signals.

[0089] Specifically, the pulse format includes not only the pulse width, but also the high-level corresponding amplitude and the low-level corresponding amplitude. The high-level corresponding amplitude refers to the current value of the pulse signal in the high-level stage, which is preset according to the signal protocol, for example, 14 mA. The low-level corresponding amplitude refers to the current value of the pulse signal in the low-level stage, which is preset according to the signal protocol, for example, 7 mA.

[0090] In this way, in step S121, the pulse width, the high level corresponding amplitude, the low level corresponding amplitude, and the pulse period are used to control the corresponding pulse signal generation circuit to output the corresponding electrical signal, so as to output the analog wheel speed signal. For example, in the process of generating the analog wheel speed signal corresponding to the wheel, when a low level of 7 mA needs to be generated, the first pulse signal generation circuit can be controlled to output a current of 7 mA, and the duration of controlling the first pulse signal generation circuit to work is determined according to the pulse period and the pulse width, so as to generate the analog wheel speed signal.

[0091] Continuing from Figure 1 , Figure 2 , Figure 4 , and in combination with the description shown in Figure 5 , in some exemplary embodiments, in step S121, based on the pulse format corresponding to the reference signal feature and the pulse period, and the preset pulse amplitude corresponding to each pulse signal generation circuit, each pulse signal generation circuit is controlled to work and output the corresponding electrical signal, which can specifically include the following steps S1211-S1213.

[0092] In step S1211, according to the low level corresponding amplitude and the preset pulse amplitude corresponding to each pulse signal generation circuit, a first target signal generation circuit with the same preset pulse amplitude as the low level corresponding amplitude is determined from each pulse signal generation circuit.

[0093] For example, continuing to take the wheel and the wheel speed analog signal generation circuit corresponding to the wheel in the above example as an example, the first target signal generation circuit in step S1211 refers to the pulse signal generation circuit with the same preset pulse amplitude as the low level corresponding amplitude in the reference signal feature. For example, if the low level corresponding amplitude in the reference signal feature is 7 mA, then the first pulse signal generation circuit or the second pulse signal generation circuit in the above example can be used as the first target signal generation circuit, and any one of the first pulse signal generation circuit or the second pulse signal generation circuit can be selected as the first target signal generation circuit. For example, taking the first pulse signal generation circuit in the above example as the first target signal generation circuit.

[0094] It is worth noting that two or more pulse signal generation circuits can also be determined as the first target signal generation circuit, but the sum of the preset pulse amplitudes of the two or more pulse signal generation circuits should be equal to the low level corresponding amplitude. For example, assuming that the low level corresponding amplitude is 10 mA, the preset pulse amplitude corresponding to the fourth pulse signal generation circuit is 5 mA, and the preset pulse amplitude corresponding to the fifth pulse signal generation circuit is 5 mA, then the first target signal generation circuit includes the fourth pulse signal generation circuit and the fifth pulse signal generation circuit.

[0095] In addition, it is worth mentioning that, usually in the design of pulse signal generating circuit, the low level corresponding amplitude is set to set a pulse signal generating circuit for outputting the low level corresponding amplitude, so that the pulse signal generating circuit can be directly used as the first target signal generating circuit.

[0096] Step S1212, according to the difference between the high level corresponding amplitude and the low level corresponding amplitude, determine the second target signal generating circuit with the same preset pulse amplitude and difference from the pulse signal generating circuit.

[0097] Specifically, the second target signal generating circuit refers to the pulse signal generating circuit with the same preset pulse amplitude and (high level corresponding amplitude-low level corresponding amplitude), that is, the same amplitude difference. The output of the electric signal and the low level corresponding amplitude of the first target signal generating circuit can form a high level corresponding amplitude signal after superposition.

[0098] For example, the high level corresponding amplitude in the reference signal feature is 14mA, the low level corresponding amplitude is 7mA, the first target signal generating circuit is the first pulse signal generating circuit in the above example (corresponding to the preset pulse amplitude of 7mA), and the difference between the high level corresponding amplitude and the low level corresponding amplitude is 7mA. Then, the second pulse signal generating circuit in the above example can be selected as the second target signal generating circuit.

[0099] It is worth mentioning that, as the first target signal generating circuit, two or more pulse signal generating circuits (not included in the pulse signal generating circuit of the first target signal generating circuit) can also be determined as the second target signal generating circuit, and the sum of the preset pulse amplitudes of the two or more pulse signal generating circuits is equal to the difference.

[0100] Step S1213, control the first target signal generating circuit to continuously output the electric signal meeting the low level corresponding amplitude, and according to the pulse width and pulse period of the reference signal feature, control the second target signal generating circuit to output the electric signal changing according to the pulse period, and the pulse width of the electric signal changing according to the pulse period is the same as the pulse width in the reference signal feature.

[0101] For example, the high level of the reference signal corresponds to an amplitude of 14 mA, and the low level corresponds to an amplitude of 7 mA. The first target signal generating circuit is the first pulse signal generating circuit in the above example (corresponding to a preset pulse amplitude of 7 mA), and the second target signal generating circuit is the second pulse signal generating circuit in the above example (corresponding to a preset pulse amplitude of 7 mA). The pulse width of the reference signal is 720 us (corresponding to a range of 616 us-720 us-828 us), and the pulse period is 36.1 ms. The following is an example for illustration.

[0102] The first pulse signal generating circuit is controlled to work to generate a current of 7 mA, and the other pulse signal generating circuits do not output. The output current signal of 7 mA (low level corresponding to amplitude) is aggregated and lasts for 35.38 ms (equivalent to outputting a low level for 35.38 ms). Then, the first pulse signal generating circuit and the second pulse signal generating circuit are controlled to work at the same time, and the third pulse signal generating circuit does not work. The superposition of the 7 mA electrical signal output by the first pulse signal generating circuit and the 7 mA electrical signal output by the second pulse signal generating circuit obtains a current signal with an amplitude of 14 mA (high level corresponding to amplitude) and lasts for 720 us (equivalent to outputting a high level for 720 us).

[0103] Then, the following is cyclically executed: only the first pulse signal generating circuit is controlled to work to generate a current of 7 mA (low level) and lasts for 35.38 ms. Then, the first pulse signal generating circuit and the second pulse signal generating circuit are controlled to work at the same time to obtain a current of 14 mA (high level) and lasts for 720 us. This cycle is repeated until the preset test wheel speed changes. According to the changed preset test wheel speed, a corresponding simulated wheel speed signal is generated.

[0104] Therefore, by steps S1211-S1213, the first target signal generating circuit capable of generating a low level corresponding amplitude is determined first, and then the second target signal generating circuit capable of generating a difference between a low level corresponding amplitude and a high level corresponding amplitude is determined. Then, by controlling the working states of the first target signal generating circuit and the second target signal generating circuit, the generation of the simulated wheel speed signal is realized. In this way, the generated simulated wheel speed signal is consistent with the wheel speed signal output by the real wheel speed sensor in terms of signal characteristics such as amplitude and pulse width, and the generation accuracy of the simulated wheel speed signal can be improved.

[0105] It is worth noting that the other pulse signal generating circuits (not belonging to the first target signal generating circuit or the second target signal generating circuit) in the wheel speed simulation signal generating circuit corresponding to the vehicle wheel, such as the third pulse signal generating circuit in the example, are controlled to be in an off state, that is, they are controlled to continuously output no electrical signal.

[0106] Step S122, superimpose the electrical signals output by each pulse signal generation circuit, and generate an analog wheel speed signal.

[0107] Specifically, in step S122, the electrical signals output by each pulse signal generation circuit in the set of wheel speed analog signal generation circuits at each time are superimposed, and an analog wheel speed signal corresponding to the wheel is obtained. For example, in the case where only the first pulse signal generation circuit outputs an electrical signal with a corresponding amplitude, since the other pulse signal generation circuits do not work and output 0 level, the electrical signal output by the first pulse signal generation circuit is the analog wheel speed signal obtained after superimposition.

[0108] Thus, through steps S121 and S122, the generation of the analog wheel speed signal is realized through the working control of the multiple pulse signal generation circuits, so that the current amplitude required by different signal protocols can be flexibly generated by adjusting the number and working state of the pulse signal generation circuits, and the signal requirements of the brake system of different vehicle models can be easily adapted.

[0109] Reference Figure 6 , Figure 6 A set of wheel speed analog signal generation circuits is shown, which includes three pulse signal generation circuits. From left to right, they are the first pulse signal generation circuit, the second pulse signal generation circuit, and the third pulse signal generation circuit. Figure 6 As shown in FIG. 1, in some exemplary embodiments, taking one of the pulse signal generation circuits as an example, the circuit structure of the other pulse signal generation circuits can refer to FIG. 1 and the structure description of the pulse signal generation circuit. Figure 6

[0110] Specifically, the pulse signal generation circuit includes a switching unit and a first resistor (denoted as R1 in the figure). One end of the first resistor R1 is connected to the positive pole of the first power supply, the other end of the first resistor R1 is connected to one end of the switching unit, and the other end of the switching unit is connected to the negative pole of the first power supply. The switching unit can be in an on or off state under control, and the negative pole of the first power supply outputs an electrical signal (current signal).

[0111] Among them, the wheel speed sensor is usually provided with a 6.3V constant direct current power supply and a ground circuit by the brake system of the vehicle to realize wheel speed detection. In this embodiment, the first power supply can also be set as the 6.3V constant direct current power supply to directly use the power supply provided by the brake system for the original wheel speed sensor.

[0112] ​Taking the first pulse signal generating circuit as an example, the switch unit responds to the control. When the switch unit is in the on state, the path where the first resistor R1 is located is turned on, the current flows out from the positive electrode of the first power supply, flows through the first resistor R1 and the turned-on switch element, and then flows out 7mA current signal from the negative electrode of the first power supply. The amplitude of the current (equivalent to the preset pulse amplitude corresponding to the pulse signal generating circuit, for example, the first pulse signal generating circuit corresponds to 7mA) is equal to the ratio of the first power supply (6.3V) to the first resistor R1. The amplitude of the output electric signal can be adjusted by setting the resistance value of the first resistor R1. For example, the resistance value of the first resistor R1 of the first pulse signal generating circuit can be set to 900Ω, so that the first pulse signal generating circuit can output a 7mA current signal when the switch unit is turned on.

[0113] When the switch unit is in the off state, the path where the first resistor R1 is located is turned off (in the cut-off state, no current flows through), at this time no current flows out from the negative electrode of the first power supply, that is, at this time the current output by the negative electrode of the first power supply is 0.

[0114] In this way, through the circuit design of the first resistor R1, the switch unit and the first power supply, and through the on-off control of the switch unit, it can be controlled whether to output an electric signal. The preset pulse amplitude can be set by the resistance value of the first resistor, so that the circuit can generate an electric signal with a corresponding preset pulse amplitude, thereby helping to generate an analog wheel speed signal.

[0115] Continuing from Figure 6 In some example embodiments, the switch unit includes an optocoupler (denoted as U in the figure), a second resistor (denoted as R2 in the figure), and a switch tube (denoted as Q in the figure).

[0116] The optocoupler U includes an anode, a cathode, an emitter and a collector. The collector of the optocoupler U is connected to one end of the first resistor R1 which is not connected to the first power supply, and the emitter of the optocoupler U is connected to the negative electrode of the first power supply.

[0117] One end of the second resistor R2 is connected to a second power supply, and the other end of the second resistor R2 is connected to the anode of the optocoupler U. The second power supply can be a 5V power supply.

[0118] The switch tube Q includes a control end, a current input end and a current output end. The current input end of the switch tube Q is connected to the cathode of the optocoupler, and the current output end of the switch tube is grounded. Specifically, the switch tube Q can be an NPN type triode, the base of the triode is the control end, the collector of the triode is the current input end, and the emitter of the triode is the current output end. In some embodiments, the switch tube Q can also be a MOS tube, etc., which will not be described here.

[0119] Specifically, referring toFigure 6 When the switch unit needs to be controlled to be in the off state, a switch control instruction representing control of the off state can be input to the control end of the switch tube Q, for example, a low-level switch control instruction. After the NPN transistor Q receives the low-level switch control instruction, it will be in the off state, that is, the emitter and collector of the transistor Q will be in the off state and no current will flow. This causes the light emitting diode side of the optocoupler U (between the anode and cathode of the optocoupler U) to be in the off state, so the emitter and collector of the optocoupler U are also in the off state. At this time, no current flows through the branch with the first resistor R1, and no current flows out of the negative terminal of the first power supply, that is, the current output by the negative terminal of the first power supply is 0.

[0120] When the switch unit needs to be controlled to be in the off state, a switch control instruction representing control of the off state can be input to the control end of the switch tube Q, for example, a low-level switch control instruction. After the NPN transistor Q receives the low-level switch control instruction, it will be in the off state, that is, the emitter and collector of the transistor Q will be in the off state and no current will flow. This causes the light emitting diode side of the optocoupler U (between the anode and cathode of the optocoupler U) to be in the off state, so the emitter and collector of the optocoupler U are also in the off state. At this time, no current flows through the branch with the first resistor R1, and no current flows out of the negative terminal of the first power supply, that is, the current output by the negative terminal of the first power supply is 0.

[0121] It is worth noting that when the first pulse signal generating circuit is configured to generate a 7mA current signal alone, the resistance of the first resistor R1 in the first pulse signal generating circuit can be 900Ω, and similarly the resistance of the first resistor R1 in the second pulse signal generating circuit can be 900Ω. When the third pulse signal generating circuit is configured to generate a 14mA current signal alone, the resistance of the first resistor R1 in the third pulse signal generating circuit can be 450Ω.

[0122] Thus, by using the optocoupler U and the switch tube Q to form a switch unit, the optical isolation between the wheel speed signal simulator and the brake system can be achieved using the optocoupler U, which can prevent the wheel speed signal simulator from being damaged when the brake system circuit is abnormal (e.g., short-circuited), thereby improving the reliability and service life of the wheel speed signal simulator.

[0123] In some embodiments, the switch unit can further include a third resistor (denoted as R3) and a fourth resistor (denoted as R4), wherein one end of the third resistor R3 is configured to receive a switch control instruction, and the other end of the third resistor R3 is connected to the control end of the switch tube Q. The switch control instruction is an instruction for controlling the state of the switch element. One end of the fourth resistor R4 is connected to the control end, and the other end of the fourth resistor R4 is connected to the current output end.

[0124] It is worth noting that each pulse signal generating circuit included in the wheel speed analog signal generating circuit can refer to the above-mentioned embodiments for its structure. Among them, each pulse signal generating circuit in the wheel speed analog signal generating circuit is connected in parallel, that is, the negative pole of the first power supply in each pulse signal generating circuit is connected to the same node (that is, the emitters of the optocouplers U of each pulse signal generating circuit are connected and converge into the node), and the final analog wheel speed signal is obtained after the currents output by the negative poles of the first power supplies of each pulse signal generating circuit are aggregated at the node to output to the measured member (that is, the brake system).

[0125] It is also worth noting that, Figure 6 The example of a set of wheel speed analog signal generating circuits (composed of multiple pulse signal generating circuits connected in parallel) corresponding to one wheel is only shown in the above-mentioned embodiment, and the wheel speed analog signal generating circuit for other wheels can refer to the example of the above-mentioned Figure 6 For example, the wheel speed analog signal generating circuit for one wheel includes a first pulse signal generating circuit, a second pulse signal generating circuit, and a third pulse signal generating circuit (the first pulse signal generating circuit, the second pulse signal generating circuit, and the third pulse signal generating circuit constitute a set of wheel speed analog signal generating circuits), and if a vehicle is equipped with four wheels, the vehicle includes four sets of wheel speed analog signal generating circuits in total, and the wheel speed analog signal generating circuit for each wheel can include the three pulse signal generating circuits in the above-mentioned example. Figure 6 The four sets of wheel speed analog signal generating circuits cooperate with the main chip that adjusts the high and low levels of I / O output to jointly constitute a complete vehicle wheel speed signal simulator.

[0126] It is worth noting that, for the vehicle wheel speed signal simulation method of the above-mentioned embodiment, based on the above-mentioned exemplary implementation forms, as a preferred embodiment, the wheel speed signal simulation method still includes the steps of Figures 1-6 , and combining Figure 7 It can include, for example: The functional test of the brake system is usually tested on a functional test platform, such as a CANoe test platform. The CANoe test platform is an integrated platform for simulation, testing, analysis, and diagnosis, and is widely used in the testing scene of electric control products in the automotive field.

[0127] The preset test wheel speed, preset wheel radius, preset number of magnetic poles, and preset number of tooth pulse ratio information required for testing are usually preset on the functional test platform.

[0128] After the functional test of the brake system, the functional test platform issues the preset test wheel speed, wheel radius, number of magnetic poles, and number of tooth pulse ratio, and then the wheel speed signal can be simulated according to the parameters issued by the functional test platform.

[0129] Specifically, for each wheel of the vehicle, based on the parameters issued by the functional test platform, and the PWM protocol (signal protocol) of the wheel speed sensor of the vehicle, the pulse period and pulse format of the pulse signal are calculated to obtain the signal characteristics.

[0130] Then, the pulse current corresponding to the wheel is output by the wheel speed signal simulator according to the pulse period and pulse format, that is, the simulated wheel speed signal corresponding to the wheel is output.

[0131] The corresponding simulated wheel speed signal is output by the corresponding wheel speed signal simulator for other wheels.

[0132] Then, the simulated wheel speed signals of the four wheels are respectively output to the measured object (i.e., the brake system) for analysis to obtain the wheel speeds of the four wheels for functional testing.

[0133] Moreover, after the brake system analyzes the simulated wheel speed signal to obtain the wheel speed of the vehicle, the wheel speed can be fed back to the functional test platform. The test engineer can check on the display panel of the functional test platform whether the analyzed wheel speed is consistent with the preset test wheel speed. For example, assuming that the preset test wheel speed is 50 km / h, if a fault occurs in the related device, etc., resulting in that the brake system analyzes the wheel speed as 30 km / h, and the functional test is performed under the condition of the wheel speed of 30 km / h, the test engineer can find on the display panel that the deviation between the wheel speed analyzed by the brake system and the preset test wheel speed is large, so as to make timely adjustment.

[0134] In the above preferred embodiment, the process of controlling the wheel speed signal simulator to output the pulse current corresponding to the wheel according to the pulse period and pulse format, and the circuit structure of the wheel speed signal simulator can still be referred to the description in the above exemplary implementation forms, and the beneficial effects of the preferred embodiment can also be referred to the description in the above exemplary implementation forms.

[0135] The vehicle wheel speed signal simulation method of the embodiment is designed as above, the signal characteristics of the wheel speed signal that should be output by the wheel speed sensor are calculated, and the wheel speed signal simulator is controlled to simulate and generate the wheel speed signal, so as to replace the use of the actual wheel speed sensor in the functional test scene of the brake system. In this way, the brake system of the vehicle does not need to be actually placed in the corresponding test working condition, but the preset test wheel speed can be flexibly adjusted to adjust the reference signal characteristics, so as to realize the simulation of the wheel speed signal.

[0136] In this way, extreme working conditions can also be achieved by adjusting the preset test wheel speed, for example, if the extreme working condition of "120km / h rapid deceleration to 0km / h" needs to be simulated, only the preset test wheel speed needs to be set, and the wheel speed signal simulator generates the simulated wheel speed signal according to the corresponding reference signal characteristics. For a large number of extreme scenarios, the test can be quickly realized by adjusting the preset test wheel speed, without the need to actually place the vehicle's braking system in a real vehicle test working condition. This makes the test of the braking system cover most of the typical and extreme working conditions during vehicle driving, thereby improving the working condition coverage. And before ensuring the reliability of the braking system function, real vehicle testing can be avoided, and testing can be performed in a simulated manner, which can also reduce the risk of safety accidents caused by abnormal braking system functions during real vehicle testing, thereby improving testing safety.

[0137] At the same time, since the embodiment replaces the actual wheel speed sensor with the simulated wheel speed signal in the functional test scenario of the braking system, the wheel speed sensor and the supporting components do not need to be additionally purchased, installed and maintained in the test, and the direct cost of hardware purchase and replacement is saved.

[0138] At the same time, the vehicle wheel speed signal simulation method of the embodiment is simulated by the wheel speed signal simulator, and is not disturbed by external environmental conditions like the actual wheel speed sensor. Therefore, the wheel speed signal received by the braking system can remain stable and accurate, so that the wheel speed calculation based on the simulated wheel speed signal can better reflect the true function level of the measured part, thereby avoiding test errors caused by environmental factors and improving the accuracy and reliability of the test results.

[0139] At the same time, through the vehicle wheel speed signal simulation method of the embodiment, the test work of the vehicle control system is no longer simply dependent on the manual clicking of the upper computer panel by the engineer to create working condition tests, but can be decoupled from the human machine through advanced environmental equipment and related tools in a fully automated script manner. For example, for the test of the braking system, if the real vehicle environment test is carried out, it undoubtedly increases the workload of the engineer's manual test, reduces the work efficiency and consumes the vehicle resources. Through the vehicle wheel speed signal simulation method of the embodiment, the functional test of the braking system can be moved from the vehicle to the laboratory, and the environmental equipment including the wheel speed signal simulator can be controlled by the program to realize the human-machine decoupled test (for example, the program script automatically outputs the corresponding preset test vehicle speed to the wheel speed signal simulator, so that the wheel speed signal simulator generates the corresponding simulated wheel speed signal to the braking system for testing according to the internal program logic), thereby improving the test efficiency and test convenience.

[0140] The embodiment of the second aspect of the application provides a vehicle test method for testing the function of the braking system of the vehicle.

[0141] The test method comprises obtaining a simulated wheel speed signal satisfying a preset test condition through the vehicle wheel speed signal simulation method in the above embodiment; and outputting the simulated wheel speed signal to the braking system, so that the braking system analyzes the simulated wheel speed signal and performs corresponding functional control, thereby realizing functional testing of the braking system.

[0142] The preset test condition comprises a preset test wheel speed, and the simulated wheel speed signal is generated according to the preset test wheel speed and output to the braking system. In this way, the braking system can respond to the simulated wheel speed signal and perform corresponding functional control, thereby completing the functional testing.

[0143] In addition, the functional testing can be ABS (Anti-lock Braking System, anti-lock braking system) testing. For example, the wheel speed signal is used to simulate a situation in which the wheel is about to lock, for example, at a preset test wheel speed of 60 km / h, a signal is suddenly generated in which the left front wheel speed suddenly drops (from 60 km / h to 10 km / h) and the other wheels maintain 60 km / h, simulating a situation in which the left front wheel is about to lock. After the braking system analyzes the simulated wheel speed signal, the ABS function should be triggered immediately to perform corresponding processing.

[0144] In addition, the functional testing can also be AEB (Autonomous Emergency Braking, autonomous emergency braking) testing, and can also be other functional testing, which will not be described here.

[0145] In specific applications, the specific generation process of the simulated wheel speed signal in the vehicle testing method of the embodiment can be referred to the related description in the above vehicle wheel speed signal simulation method embodiment, which will not be described here.

[0146] In some exemplary embodiments, the test method further comprises obtaining the wheel speed of the vehicle by the braking system analyzing the simulated wheel speed signal, and outputting the wheel speed.

[0147] Specifically, the wheel speed can be returned to the functional testing platform. The tester can check on the display panel of the functional testing platform whether the analyzed wheel speed is consistent with the preset test wheel speed, so that the tester can determine whether the analysis function of the braking system for the simulated wheel speed signal is normal. If there is no deviation or the deviation is small, it means that the braking system can accurately identify the simulated wheel speed signal, and the subsequent functional testing can continue; if the deviation is large or the data is abnormal (such as showing a negative value), it means that the wheel speed analysis logic of the braking system has a problem, at which time the testing can be paused and the fault can be checked, and after the analysis function is restored to normal, the subsequent testing process can be promoted. In this way, the problem that the subsequent functional testing obtains invalid results due to analysis errors and affects the accuracy of the braking system testing can be avoided, thereby the testing accuracy can be improved.

[0148] The vehicle test method of the embodiment can simulate the generation of wheel speed signals by controlling the wheel speed signal simulator, so as to replace the use of the actual wheel speed sensor in the functional test scene of the braking system. In this way, most of the typical and extreme working conditions during vehicle driving can be covered, the working condition coverage rate can be improved, real vehicle testing is not required, the risk of safety accidents caused by the uncertainty of the reliability of the braking system function during real vehicle testing can be reduced, and the testing safety can be improved.

[0149] The above merely describes some embodiments of the present application and is not intended to limit the present application. The technical features or structures in the foregoing different embodiments can be combined as needed to form other specific technical solutions. Various modifications and changes can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for simulating vehicle wheel speed signals, characterized in that, The simulation method includes: The signal characteristics of the wheel speed signal corresponding to the preset test wheel speed are obtained, wherein the wheel speed signal is the signal that the wheel speed sensor should output when it detects the preset test wheel speed; Using the aforementioned signal features as reference signal features, the wheel speed signal simulator is controlled to generate a simulated wheel speed signal with the same signal features as the reference signal features, and the simulated wheel speed signal is output to the vehicle's braking system, so that the braking system can parse the simulated wheel speed signal to obtain the vehicle's wheel speed and perform functional testing. The preset test wheel speed is the wheel test speed required for the functional test of the braking system of the vehicle.

2. The vehicle wheel speed signal simulation method according to claim 1, characterized in that, The wheel speed signal output by the wheel speed sensor is a pulse signal. The signal characteristics of the wheel speed signal include the pulse period and the pulse format. The step of acquiring the signal characteristics of the wheel speed signal corresponding to the preset test wheel speed includes: The pulse format of the wheel speed signal is determined based on the preset test wheel speed and the signal protocol corresponding to the wheel speed sensor; Obtain the pulse period of the wheel speed signal that the wheel speed sensor should output, assuming that the wheel speed sensor detects the preset test wheel speed.

3. The vehicle wheel speed signal simulation method according to claim 2, characterized in that, The step of obtaining the pulse period of the wheel speed signal that the wheel speed sensor should output, assuming that the wheel speed sensor detects the preset test wheel speed, includes: Get the wheel radius; The pulse period of the wheel speed signal is calculated using a preset formula based on the ratio of the number of pulses to the number of teeth of the wheel speed sensor, the number of magnetic poles of the gear magnetic ring of the wheel speed sensor, and the wheel radius. The tooth count pulse ratio represents the ratio between the number of pulses generated by the monitoring component of the wheel speed sensor and the number of magnetic poles passing through the monitoring component in the gear magnetic ring.

4. The vehicle wheel speed signal simulation method according to claim 3, characterized in that, The preset relation is: ； Where T is the pulse period of the pulse signal, v is the preset test wheel speed, r is the wheel radius, N is the number of magnetic poles, and k is the ratio of the number of tooth pulses.

5. The vehicle wheel speed signal simulation method according to claim 2, characterized in that, The wheel speed signal simulator includes multiple pulse signal generation circuits, each with a corresponding preset pulse amplitude. The control of the wheel speed signal simulator to generate a simulated wheel speed signal with signal characteristics identical to the reference signal characteristics includes: Based on the pulse format and pulse period corresponding to the characteristics of the reference signal, and the preset pulse amplitude corresponding to each pulse signal generation circuit, at least two of the pulse signal generation circuits are controlled to work and output corresponding electrical signals. The electrical signals output by each of the pulse signal generation circuits are superimposed to generate the simulated wheel speed signal.

6. The vehicle wheel speed signal simulation method according to claim 5, characterized in that, The pulse format includes a high-level corresponding amplitude, a low-level corresponding amplitude, and a pulse width. Based on the pulse format and pulse period corresponding to the characteristics of the reference signal, and the preset pulse amplitude corresponding to each pulse signal generation circuit, the operation of each pulse signal generation circuit is controlled, and corresponding electrical signals are output, including: Based on the amplitude corresponding to the low level and the preset pulse amplitude corresponding to each pulse signal generation circuit, a first target signal generation circuit whose preset pulse amplitude is the same as the amplitude corresponding to the low level is determined from each pulse signal generation circuit; Based on the difference between the amplitude corresponding to the high level and the amplitude corresponding to the low level, a second target signal generation circuit with the same preset pulse amplitude as the difference is determined from each of the pulse signal generation circuits; The first target signal generation circuit is controlled to continuously output an electrical signal that meets the amplitude corresponding to the low level. Based on the pulse width and pulse period of the reference signal characteristics, the second target signal generation circuit is controlled to output an electrical signal that varies according to the pulse period, and the pulse width of the electrical signal that varies according to the pulse period is the same as the pulse width in the reference signal characteristics.

7. The vehicle wheel speed signal simulation method according to claim 5, characterized in that: Each of the pulse signal generation circuits includes a switching unit and a first resistor; One end of the first resistor is connected to the positive terminal of the first power supply, and the other end of the first resistor is connected to one end of the switching unit, and the other end of the switching unit is connected to the negative terminal of the first power supply. The switching unit can be in an on or off state under control, and outputs the electrical signal at the negative terminal of the first power supply.

8. The vehicle wheel speed signal simulation method according to claim 7, characterized in that: The switching unit includes an optocoupler, a second resistor, and a switching transistor; The optocoupler includes an anode, a cathode, an emitter, and a collector. The collector of the optocoupler is connected to the end of the first resistor that is not connected to the first power supply, and the emitter of the optocoupler is connected to the negative terminal of the first power supply for outputting a corresponding electrical signal. One end of the second resistor is connected to the second power supply, and the other end of the second resistor is connected to the anode of the optocoupler; The switching transistor includes a control terminal, a current input terminal, and a current output terminal. The current input terminal of the switching transistor is connected to the cathode of the optocoupler, and the current output terminal of the switching transistor is grounded.

9. A vehicle testing method for performing functional tests on the braking system of the vehicle, characterized in that: The testing method includes obtaining a simulated wheel speed signal that meets preset test conditions by the vehicle wheel speed signal simulation method according to any one of claims 1 to 8; The simulated wheel speed signal is output to the braking system, so that the braking system can analyze the simulated wheel speed signal and execute the corresponding functional control, thereby realizing the functional test of the braking system.

10. The vehicle testing method according to claim 9, characterized in that: The testing method also includes the braking system obtaining the vehicle's wheel speed by analyzing the simulated wheel speed signal and outputting the wheel speed.

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