Wheel speed simulation circuit and wheel speed test system

Abstract

The invention discloses a wheel speed simulation circuit and a wheel speed test system. The wheel speed simulation circuit comprises a current signal generation module and a wheel speed output protection module. The current signal generation module is electrically connected with a current control pin of the controller; the current signal generation module comprises a current control module and a current signal conversion module; the current control module is used for generating an initial current signal under the control of the current control pin; the current signal conversion module is used for amplifying the initial current signal to obtain a wheel speed analog signal, and the wheel speed analog signal is used for simulating a signal output by a real wheel speed sensor; the wheel speed output protection module comprises a voltage protection module and a rectifier bridge module; the voltage protection module is electrically connected with the current signal conversion module; the rectifier bridge module is connected with the voltage protection module in parallel, the rectifier bridge module is used for outputting a wheel speed simulation signal to an external speed processing circuit, and the wheel speed simulation circuit provided by the invention can realize wheel speed simulation with comprehensive functions.

Description

Technical Field

[0001] The present application belongs to the field of sensor simulation technology, and in particular, relates to a wheel speed simulation circuit and a wheel speed testing system. Background Art

[0002] With the rapid growth of the automobile market for many consecutive years, people have higher and higher requirements for automobile driving safety technology, especially active safety technology. Whether it is the widely used anti-lock brake system (ABS), electronic stability program (ESP), or the emerging advanced driver assistance system (ADAS), forward collision warning system (FCWS), it is necessary to accurately obtain the current wheel speed of the vehicle. The use of real wheel speed sensors to generate wheel speed signals requires additional configuration of rotating motors, speed measuring gears and other necessary components, making the test system complex to control, bulky and expensive. In addition, in the prior art, the output signal of the real wheel speed sensor can be simulated by a wheel speed simulation device, but the function is relatively single, which is not conducive to the use in automobile or rail vehicle testing.

[0003] Therefore, how to achieve comprehensive wheel speed simulation is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application provides a wheel speed simulation circuit and a wheel speed testing system, which can realize a comprehensive wheel speed simulation.

[0005] On the one hand, an embodiment of the present application provides a wheel speed simulation circuit, which includes a current signal generating module and a wheel speed output protection module; the wheel speed simulation circuit is electrically connected to a controller, and the current signal generating module is electrically connected to a current control pin of the controller; The current signal generating module comprises a current control module and a current signal converting module; the current control module is electrically connected to the current signal converting module; the current control module is used to generate an initial current signal under the control of the current control pin; the current signal converting module is used to amplify the initial current signal to obtain a wheel speed simulation signal, and the wheel speed simulation signal is used to simulate the signal output by the real wheel speed sensor; The wheel speed output protection module includes a voltage protection module and a rectifier bridge module; the voltage protection module is electrically connected to the current signal conversion module; the rectifier bridge module is connected in parallel with the voltage protection module, and the rectifier bridge module is used to output the wheel speed analog signal to an external speed processing circuit.

[0006] In an exemplary embodiment, the current control module includes a first current control circuit, a second current control circuit and a third current control circuit; the current control pins include a first current control pin, a second current control pin and a third current control pin; the first current control circuit generates a first initial current signal under the control of the first current control pin; the second current control circuit generates a second initial current signal under the control of the second current control pin; the third current control circuit generates a third initial current signal under the control of the third current control pin; the first initial current signal is used to simulate a low level output by multiple types of real wheel speed sensors, the second initial current signal and the third initial current signal are combined to simulate a high level output by multiple types of real wheel speed sensors, and the current value of the third initial current signal is greater than the current value of the second initial current signal.

[0007] In an exemplary embodiment, the first current control circuit includes a first transistor, a first resistor, a second resistor, and a first diode; The first end of the first resistor is electrically connected to the reference voltage output pin of the current signal conversion module, and the cathode of the first diode is electrically connected to the current input pin of the current signal conversion module; the second end of the first resistor is electrically connected to the anode of the first diode and the collector of the first transistor, the base of the first transistor is electrically connected to the first end of the second resistor, the emitter of the first transistor is grounded, and the second end of the second resistor is electrically connected to the first current control pin.

[0008] In an exemplary embodiment, the voltage protection module includes a capacitor and a transient suppression diode; The first end of the capacitor is electrically connected to the power supply pin of the current signal conversion module, and the second end of the capacitor is electrically connected to the current output pin of the current signal conversion module; the transient suppression diode and the capacitor form a parallel structure.

[0009] In an exemplary embodiment, the rectifier bridge module includes a second diode, a third diode, a fourth diode and a fifth diode; the cathode of the second diode and the cathode of the fourth diode are both electrically connected to the power supply pin of the current signal conversion module, the anode of the third diode and the anode of the fifth diode are both electrically connected to the current output pin, the cathode of the third diode is electrically connected to the anode of the second diode, and the cathode of the fifth diode is electrically connected to the anode of the fourth diode; a first signal terminal is led out at the anode of the second diode, and a second signal terminal is led out at the cathode of the fifth diode; The first signal terminal is electrically connected to the speed positive signal terminal, and the second signal terminal is electrically connected to the speed negative signal terminal; or, The first signal terminal is electrically connected to the speed negative signal terminal, and the second signal terminal is electrically connected to the speed positive signal terminal; the speed positive signal terminal is one end of the external speed processing circuit, and the speed positive signal terminal is used to provide voltage to the wheel speed simulation circuit; the speed negative signal terminal is the other end of the external speed processing circuit, and the speed negative signal terminal is used to receive the wheel speed simulation signal generated by the wheel speed simulation circuit.

[0010] In an exemplary embodiment, the controller includes a wheel speed signal receiving pin, and the wheel speed simulation circuit also includes a wheel speed feedback acquisition module. The wheel speed signal receiving pin is electrically connected to the current signal generating module through the wheel speed feedback acquisition module. The wheel speed feedback acquisition module is used to transmit the wheel speed simulation signal to the wheel speed signal receiving pin so that the controller performs signal diagnosis on the wheel speed simulation signal.

[0011] In an exemplary embodiment, the wheel speed feedback acquisition module includes an operational amplifier, a third resistor, a fourth resistor, and a hysteresis comparator; The non-inverting input terminal of the operational amplifier is electrically connected to the current output pin of the current signal conversion module, and the inverting input terminal of the operational amplifier is electrically connected to the reference ground pin of the current signal conversion module; the output terminal of the operational amplifier is electrically connected to the first end of the third resistor, the second end of the third resistor is electrically connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded; The output end of the hysteresis comparator is electrically connected to the wheel speed signal receiving pin, the input of the first comparison end of the hysteresis comparator is the voltage divided by the third resistor and the fourth resistor; the input of the second comparison end of the hysteresis comparator is the reference voltage.

[0012] In an exemplary embodiment, the hysteresis comparator includes a comparator, a fifth resistor, a sixth resistor, and a seventh resistor; The first comparison terminal of the comparator is electrically connected to the second terminal of the third resistor, the first terminal of the fifth resistor is electrically connected to the second comparison terminal of the comparator, and the second terminal of the fifth resistor is electrically connected to the output terminal of the comparator; The first end of the sixth resistor is electrically connected to the power supply, the second end of the sixth resistor and the first end of the seventh resistor are electrically connected to the second comparison end of the comparator, and the second end of the seventh resistor is grounded.

[0013] In an exemplary embodiment, the wheel speed simulation circuit further includes a wheel speed fault simulation module, the wheel speed fault simulation module is electrically connected to the controller and is used to simulate a fault occurring in the wheel speed sensor under the control of the controller; The wheel speed fault simulation module includes a first switch tube, an eighth resistor, a second switch tube and a third switch tube; The source of the first switch tube is electrically connected to the battery module, the drain of the first switch tube is electrically connected to the second switch tube and the third switch tube in sequence, and then electrically connected to the first end of the eighth resistor, and the speed positive signal end of the external speed processing circuit is electrically connected between the drain of the second switch tube and the source of the third switch tube; the second end of the eighth resistor is grounded; The gates of the first switch tube, the second switch tube, and the third switch tube are all electrically connected to the controller.

[0014] On the other hand, the present application also provides a wheel speed test system, which includes a host computer, a controller, and a plurality of wheel speed simulation circuits according to any one of the above embodiments; the host computer communicates with the controller through a serial port; the wheel speed simulation circuits are arranged in a one-to-one correspondence with the vehicle wheels; the wheel speed simulation circuits are electrically connected to the controller; The host computer is used to send the simulated wheel speed sensor type to the controller, and the controller controls the current signal generating module to generate a wheel speed simulation signal corresponding to the simulated wheel speed sensor type, and outputs it via the wheel speed output protection module.

[0015] The wheel speed simulation circuit and wheel speed testing system provided by the present application have the following technical effects: The wheel speed simulation circuit provided in the embodiment of the present application includes a current signal generating module and a wheel speed output protection module; wherein the current signal generating module includes a current control module and a current signal conversion module; by converting the high and low levels of the current control pin of the controller, the current control module generates an initial current signal under the control of the current control pin, and amplifies the initial current signal through the current signal conversion module to obtain a wheel speed simulation signal, thereby simulating the signal output by the real wheel speed sensor. In the wheel speed simulation circuit provided in the present application, the circuit module for generating the wheel speed simulation signal has a simple structure and low cost, and can be accurately controlled by the controller to output current signals of different current amplitudes, thereby realizing the simulation of multiple types of wheel speed sensors, and has strong versatility. In addition, in order to correctly transmit the wheel speed simulation signal to the external speed processing circuit, the wheel speed simulation circuit provided in the present application also includes a wheel speed output protection module to realize the positive and negative access of the external speed processing circuit and realize the hot plug function. Therefore, the wheel speed simulation circuit provided in the embodiment of the present application can realize a comprehensive wheel speed simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a schematic diagram of the module structure of the wheel speed simulation circuit provided in an embodiment of the present application.

[0018] Figure 2 Schematic diagram of a wheel speed simulation circuit provided in an embodiment of the present application.

[0019] Figure 3 It is a circuit diagram of the first current control circuit provided in an embodiment of the present application.

[0020] Figure 4 It is a circuit diagram of the wheel speed output protection module provided in an embodiment of the present application.

[0021] Figure 5 It is a circuit diagram of the wheel speed feedback collection module provided in an embodiment of the present application.

[0022] Figure 6 Schematic diagram of a circuit of a wheel speed fault simulation module provided in an embodiment of the present application.

[0023] Figure 7 It is a structural schematic diagram of the wheel speed testing system provided in an embodiment of the present application.

[0024] Among them, the reference numerals in the figure correspond to: 1-wheel speed simulation circuit, 2-controller, 100-current signal generating module, 200-wheel speed output protection module, 300-wheel speed feedback acquisition module, 400-wheel speed fault simulation module, 110-current control module, 120-current signal conversion module, 210-voltage protection module, 220-rectifier bridge module, 111-first current control circuit, 112-second current control circuit, 113-third current control circuit. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] In automobile or rail vehicle systems, speed signals need to be collected. Speed ​​signals come from wheel speed sensors, which are installed at the wheel ends of vehicles and collect wheel speed signals through speed measuring gears. Currently used wheel speed sensors are mostly active wheel speed sensors, and the signals are current square wave signals, which are mainly divided into three categories: a) Non-intelligent wheel speed sensors: output high current 14mA, low current 7mA, and frequency signals with a duty cycle of 50%; b) Pulse Width Modulation (PWM) protocol intelligent wheel speed sensors: PWM coding is added to the non-intelligent wheel speed sensors, and can output information including installation air gap changes, wheel forward and reverse rotation, and other alarm information; c) AK protocol intelligent wheel speed sensors: A high-level 28mA current square wave is added, which can better output wheel speed signals at low speeds (including zero speed). AK protocol is the standard interface between wheel speed sensors (WSS) and electronic control units.

[0028] During the development, production and testing of automobiles or rail vehicles, it is often necessary to generate speed signals to carry out experimental research such as anti-skid and locking research. The use of real wheel speed sensors to generate wheel speed signals requires additional configuration of necessary components such as rotating motors and speed measuring gears, making the test system complex to control, bulky and expensive; while the wheel speed simulation generating device of the prior art has relatively simple functions and can usually only simulate a single type of wheel speed sensor signal, which is not conducive to use in automobile or rail vehicle experiments and tests. Therefore, the embodiments of the present application provide a wheel speed simulation circuit and a wheel speed test system to achieve comprehensive wheel speed simulation.

[0029] Figure 1 It is a schematic diagram of the module structure of the wheel speed simulation circuit provided in an embodiment of the present application.

[0030] like Figure 1 As shown, the wheel speed simulation circuit 1 provided in the embodiment of the present application includes a current signal generating module 100 and a wheel speed output protection module 200; The wheel speed simulation circuit 1 is electrically connected to the controller 2, and specifically, the current signal generating module 100 is electrically connected to the current control pin of the controller 2; The current signal generating module 100 includes a current control module 110 and a current signal conversion module 120; the current control module 110 is electrically connected to the current signal conversion module 120; the current control module 110 is used to generate an initial current signal under the control of a current control pin; the current signal conversion module 120 is used to amplify the initial current signal to obtain a wheel speed simulation signal, wherein the wheel speed simulation signal is used to simulate the signal output by a real wheel speed sensor.

[0031] By changing the current control pin to output a high level or a low level, the current control module 110 can generate an initial current signal, which can be a square wave signal. After amplification, a wheel speed analog signal is obtained.

[0032] In one example, the current amplification factor of the current signal conversion module 120 may be 100. The current signal conversion module 120 may be a current loop transmitter chip, such as an integrated chip of model XTR115, which can generate a maximum current of 32 mA.

[0033] The wheel speed output protection module 200 includes a voltage protection module 210 and a rectifier bridge module 220. The voltage protection module 210 is electrically connected to the current signal conversion module 120. The rectifier bridge module 220 is connected in parallel with the voltage protection module 210. The rectifier bridge module 220 is used to output the wheel speed analog signal to the external speed processing circuit.

[0034] Similar to the access method of the real wheel speed sensor, taking the left front wheel as an example, the wheel speed simulation circuit 1 is connected to the speed positive signal terminal WSP_FL and the speed negative signal terminal WSS_FL of the external speed processing circuit. The rectifier bridge module 220 allows the speed positive signal terminal and the speed negative signal terminal to be connected to the wheel speed simulation circuit 1 in both positive and negative directions, effectively avoiding the risk of circuit burning due to reverse connection of the speed positive signal terminal and the speed negative signal terminal.

[0035] The voltage protection module 210 is used to absorb the surge voltage generated when the external speed processing circuit is connected, thereby realizing hot plugging and protecting the subsequent circuit.

[0036] The wheel speed simulation circuit provided in the embodiment of the present application includes a current signal generating module and a wheel speed output protection module; wherein the current signal generating module includes a current control module and a current signal conversion module; by converting the high and low levels of the current control pin of the controller, the current control module generates an initial current signal under the control of the current control pin, and amplifies the initial current signal through the current signal conversion module to obtain a wheel speed simulation signal, thereby simulating the signal output by the real wheel speed sensor. In the wheel speed simulation circuit provided in the present application, the circuit module for generating the wheel speed simulation signal has a simple structure and low cost, and can be accurately controlled by the controller to output current signals of different current amplitudes, thereby realizing the simulation of multiple types of wheel speed sensors, and has strong versatility. In addition, in order to correctly transmit the wheel speed simulation signal to the external speed processing circuit, the wheel speed simulation circuit provided in the present application also includes a wheel speed output protection module to realize the positive and negative access of the external speed processing circuit and realize the hot plug function. Therefore, the wheel speed simulation circuit provided in the embodiment of the present application can realize a comprehensive wheel speed simulation.

[0037] Figure 2 Schematic diagram of a wheel speed simulation circuit provided in an embodiment of the present application.

[0038] like Figure 2 As shown, the current control module 110 includes a first current control circuit 111, a second current control circuit 112 and a third current control circuit 113; Among them, the current signal conversion module 120 can be a chip U1; the chip U1 includes 8 pins, among which pin 7 is a power supply pin, which is connected to the speed positive signal end of the external speed processing circuit for powering the integrated chip U1, and is also connected to the collector C of the external transistor Q4 for power supply; pins 5 and 6 are respectively connected to the emitter E and base B of the external transistor Q4; pin 4 is a current signal output, connected to the speed negative signal end of the external speed processing circuit; pin 1 is a reference reference voltage output pin, used to output a 2.5V voltage; pin 2 is a current input pin, and the chip U1 amplifies the current input to pin 2 by G times and outputs it through pin 4, where G is the amplification factor; pin 3 is a reference ground pin.

[0039] The current control pins of the controller 2 include a first current control pin FL_7mA, a second current control pin FL_14mA and a third current control pin FL_28mA. In order to have the same amplitude as the actual wheel speed sensor output signal, in the embodiment of the present application, the first current control circuit 111 generates a first initial current signal under the control of the first current control pin; wherein the first initial current signal may be 7 uA; the second current control circuit 112 generates a second initial current signal under the control of the second current control pin; wherein the second initial current signal may be 7 uA; the third current control circuit 113 generates a third initial current signal under the control of the third current control pin; the third initial current signal is 14uA.

[0040] By comparing the signals output by different types of real wheel speed sensors, the first initial current signal can be used to simulate the low level (0mA or 7mA) output by multiple types of real wheel speed sensors after signal amplification, and the second initial current signal and the third initial current signal can be combined after signal amplification to simulate the high level (14mA or 28mA) output by multiple types of real wheel speed sensors, which can realize the simulation of multiple types of wheel speed sensors and has strong versatility. It should be noted that in the embodiment of the present application, the current value of the third initial current signal is greater than the current value of the second initial current signal.

[0041] Figure 3 It is a circuit diagram of the first current control circuit provided in an embodiment of the present application.

[0042] like Figure 3 As shown, the first current control circuit 111 includes a first transistor Q1, a first resistor R1, a second resistor R2 and a first diode D1; The first end of the first resistor R1 is electrically connected to the reference voltage output pin of the current signal conversion module 120, and the cathode of the first diode D1 is electrically connected to the current input pin of the current signal conversion module 120; the second end of the first resistor R1 is electrically connected to the anode of the first diode D1 and the collector C of the first transistor Q1, the base B of the first transistor Q1 is electrically connected to the first end of the second resistor R2, the emitter E of the first transistor Q1 is grounded, and the second end of the second resistor R2 is electrically connected to the first current control pin.

[0043] The working principle of the first current control circuit 111 is: the first current control pin outputs a high level and a low level to control the conduction and shutoff of the first transistor Q1, thereby controlling the current flowing into the current signal conversion module 120. Specifically, when the controller 2 controls the first current control pin FL_7mA to be a high level, the first transistor Q1 is turned on, the positive electrode voltage of the first diode D1 is almost 0, and the first diode D1 cannot be turned on, so no current flows into the chip U1; when the controller 2 controls the first current control pin FL_7mA to be a low level, the first transistor Q1 is turned off, and the current input pin current flowing into the chip U1 through the first current control circuit 111, that is, the first initial current signal is:

[0044] in, is the voltage at the first end of R1, which is equal to 2.5V. is the voltage at the second end of R1, which is equal to 0.2V. is the first initial current signal, and the value of R1 is 32.8kΩ. Substituting it into the above formula, we can get: Equal to 70uA.

[0045] Similarly, the second current control circuit 112 includes a transistor Q2, a resistor R3, a resistor R4 and a diode D2; The first end of the resistor R3 is electrically connected to the reference voltage output pin of the current signal conversion module 120, and the cathode of the diode D2 is electrically connected to the current input pin of the current signal conversion module 120; the second end of the resistor R3 is electrically connected to the anode of the diode D2 and the collector C of the transistor Q2, the base B of the transistor Q2 is electrically connected to the first end of the resistor R4, the emitter E of the transistor Q2 is grounded, and the second end of the resistor R4 is electrically connected to the second current control pin.

[0046] The working principle of the second current control circuit 112 is: the second current control pin outputs a high level and a low level to control the conduction and shutoff of the transistor Q2, thereby controlling the current flowing into the current signal conversion module 120. Specifically, when the controller 2 controls the second current control pin FL_14mA to be a high level, the transistor Q2 is turned on, the positive electrode voltage of the diode D2 is almost 0, and the diode D2 cannot be turned on, so no current flows into the chip U1; when the controller 2 controls the second current control pin FL_14mA to be a low level, the transistor Q2 is turned off, and the current input pin current flowing into the chip U1 through the second current control circuit 112 is:

[0047] in, is the voltage at the first end of R3, which is equal to 2.5V. is the voltage at the second end of R3, which is equal to 0.2V. is the second initial current signal, and the value of R3 is 32.8kΩ. Substituting it into the above formula, we can get: Equal to 70uA.

[0048] Similarly, the third current control circuit 113 includes a transistor Q3, a resistor R5, a resistor R6 and a diode D3; The first end of the resistor R5 is electrically connected to the reference voltage output pin of the current signal conversion module 120, and the cathode of the diode D3 is electrically connected to the current input pin of the current signal conversion module 120; the second end of the resistor R5 is electrically connected to the anode of the diode D3 and the collector C of the transistor Q3, the base B of the transistor Q3 is electrically connected to the first end of the resistor R6, the emitter E of the transistor Q3 is grounded, and the second end of the resistor R6 is electrically connected to the third current control pin.

[0049] The working principle of the third current control circuit 113 is: the third current control pin outputs a high level and a low level to control the conduction and shutoff of the transistor Q3, thereby controlling the current flowing into the current signal conversion module 120. Specifically, when the controller 2 controls the second current control pin FL_28mA to be a high level, the transistor Q3 is turned on, the positive electrode voltage of the diode D3 is almost 0, and the diode D3 cannot be turned on, so no current flows into the chip U1; when the controller 2 controls the third current control pin FL_28mA to be a low level, the transistor Q3 is turned off, and the current input pin current flowing into the chip U1 through the third current control circuit 113 is:

[0050] in, is the voltage at the first end of R5, which is equal to 2.5V. is the voltage at the second end of R5, which is equal to 0.2V. is the third initial current signal, and the value of R5 is 16.4kΩ. Substituting it into the above formula, we can get: Equal to 140uA.

[0051] Therefore, the current flowing into the current signal conversion module 120, that is, the initial current signal, is the sum of the currents output by the first current control circuit 111, the second current control circuit 112, and the third current control circuit 113, which can be obtained by the following formula:

[0052] in, is the initial current signal, is the first initial current signal, is the second initial current signal, is the third initial current signal, , , Respectively represent the on and off states of transistors Q1, Q2, and Q3. When transistors Q1, Q2, and Q3 are on, the corresponding , , is 0, when transistors Q1, Q2, and Q3 are turned off, the corresponding , , is 1.

[0053] Since the current signal conversion module 120 is used to amplify the initial current, when the current amplification factor G is 100, the current signal output by the current signal conversion module 120 can be determined by the following formula:

[0054] in, is the current signal output by the current signal conversion module 120, that is, the wheel speed simulation signal, is the initial current signal, and G is the current amplification factor of the current signal conversion module 120.

[0055] The relationship between the high and low levels output by the current control pin of the controller 2 and the wheel speed analog signal output by the current signal generating module 100 is shown in Table 1.

[0056]

[0057] Among them, H indicates that the current control pin outputs a high level, and L indicates that the current control pin outputs a low level. Through the current signal generating module of the embodiment of the present application, the current control pin can be used to control the current control module to generate initial current signals of various values, and after being amplified by the current signal conversion module, various types of wheel speed signals output by real wheel speed sensors can be simulated.

[0058] Figure 4 It is a circuit diagram of the wheel speed output protection module provided in an embodiment of the present application.

[0059] After the current signal generating module 100 generates the wheel speed analog signal, in order to correctly transmit the wheel speed analog signal to the external speed processing circuit, a voltage protection module 210 is further provided in the embodiment of the present application. The voltage protection module 210 includes a capacitor C1 and a transient suppression diode TVS1; The first end of the capacitor C1 is electrically connected to the power supply pin of the current signal conversion module 120, and the second end of the capacitor C1 is electrically connected to the current output pin of the current signal conversion module 120; the transient suppression diode TVS1 and the capacitor C1 form a parallel structure, wherein the capacitor C1 and the transient suppression diode TVS1 are used to absorb external surge voltage and protect the subsequent circuit, thereby realizing hot plugging.

[0060] like Figure 4 As shown, a rectifier bridge module 220 is also provided in the embodiment of the present application, and the rectifier bridge module 220 includes a second diode D4, a third diode D5, a fourth diode D6 and a fifth diode D7; the cathode of the second diode D4 and the cathode of the fourth diode D6 are both electrically connected to the power supply pin, the anode of the third diode D5 and the anode of the fifth diode D7 are both electrically connected to the current output pin, the cathode of the third diode D5 is electrically connected to the anode of the second diode D4, and the cathode of the fifth diode D7 is electrically connected to the anode of the fourth diode D6; a first signal terminal is led out at the anode of the second diode D4, and a second signal terminal is led out at the cathode of the fifth diode D7; The rectifier bridge module is used to support the positive and negative speed signal terminals of the external speed signal processing circuit. Specifically, the first signal terminal can be electrically connected to the positive speed signal terminal WSP_FL, and the second signal terminal can be electrically connected to the negative speed signal terminal WSS_FL; or, the first signal terminal can be electrically connected to the negative speed signal terminal WSS_FL, and the second signal terminal can be electrically connected to the positive speed signal terminal WSP_FL.

[0061] It should be noted that the positive speed signal terminal is one end of the external speed processing circuit, and the positive speed signal terminal is used to provide voltage to the wheel speed simulation circuit 1; the negative speed signal terminal is the other end of the external speed processing circuit, and the negative speed signal terminal is used to receive the wheel speed simulation signal generated by the wheel speed simulation circuit 1.

[0062] Through the above-mentioned rectifier bridge module, the first signal terminal and the second signal terminal can realize the correct transmission of the wheel speed simulation signal regardless of whether they are connected to the speed positive signal terminal WSP_FL or the speed negative signal terminal WSS_FL. For example, when the first signal terminal is connected to the speed positive signal terminal WSP_FL and the second signal terminal is connected to the speed negative signal terminal WSS_FL, the signal can flow out to the second signal terminal via the first signal terminal, the second diode D4, the current signal generating module 100, and the fifth diode D7, and then flow out to the speed negative signal terminal WSS_FL. For another example, when the first signal terminal is connected to the speed negative signal terminal WSS_FL and the second signal terminal is connected to the speed positive signal terminal WSP_FL, the signal can flow out to the first signal terminal via the second signal terminal, the fourth diode D6, the current signal generating module 100, and the third diode D5, and then flow out to the speed negative signal terminal WSS_FL. Therefore, the above-mentioned rectifier bridge module can effectively avoid the circuit burning due to the reverse connection of the positive and negative signal terminals.

[0063] It should be understood that the above-mentioned speed positive signal terminal WSP_FL and speed negative signal terminal WSS_FL are both signal terminals corresponding to the left front wheel. When it is necessary to simulate the wheel speed signals of other wheels, the corresponding signal terminals of other wheels are connected accordingly.

[0064] Figure 5 It is a circuit diagram of the wheel speed feedback collection module provided in an embodiment of the present application.

[0065] The wheel speed simulation circuit 1 provided in the embodiment of the present application also includes a wheel speed feedback acquisition module 300. It should be noted that the controller 2 includes a wheel speed signal receiving pin, which is electrically connected to the current signal generating module 100 through the wheel speed feedback acquisition module 300, and the wheel speed feedback acquisition module 300 is used to transmit the wheel speed simulation signal to the wheel speed signal receiving pin, so that the controller 2 performs signal diagnosis on the wheel speed simulation signal. Specifically, the controller 2 parses the speed signal according to the feedback signal processed by the wheel speed feedback acquisition module 300, and compares it with the expected output signal. If it does not match, the output fault of the wheel speed simulation circuit can be reported through the serial port.

[0066] like Figure 5 As shown, the wheel speed feedback acquisition module 300 includes an operational amplifier OP1, a third resistor R7, a fourth resistor R8 and a hysteresis comparator; The non-inverting input terminal of the operational amplifier OP1 is electrically connected to the current output pin of the current signal conversion module 120, and the inverting input terminal of the operational amplifier OP1 is electrically connected to the reference ground pin of the current signal conversion module 120; the output terminal of the operational amplifier OP1 is electrically connected to the first end of the third resistor R7, the second end of the third resistor R7 is electrically connected to the first end of the fourth resistor R8, and the second end of the fourth resistor R8 is grounded.

[0067] Since there is a resistor (with a resistance of 25Ω) between the current output pin and the reference ground pin of the current signal conversion module 120, and the current signal output by the current signal conversion module 120, that is, the wheel speed simulation signal, will flow through the resistor, a voltage will be generated. By amplifying and comparing the voltage, high and low level pulses can be generated. The controller 2 receives the high and low level pulse signals and matches them with the preset pulse signals, thereby realizing the diagnosis of the output signal of the current signal generating module 100.

[0068] It should be noted that when current flows through the chip U1, a maximum voltage of 0.7V can be generated. The model of the operational amplifier OP1 can be INA296A1-Q1. The operational amplifier OP1 is a current amplifier with an amplification factor of 10, so the maximum output voltage of the operational amplifier OP1 is 7V. The output voltage of the operational amplifier OP1 is transmitted to the hysteresis comparator after being divided by the third resistor R7 and the fourth resistor R8.

[0069] The output end of the hysteresis comparator is electrically connected to the wheel speed signal receiving pin, the input of the first comparison end of the hysteresis comparator is the voltage after the voltage is divided by the third resistor R7 and the fourth resistor R8; the input of the second comparison end of the hysteresis comparator is the reference voltage, which includes the first voltage comparison threshold and the second voltage comparison threshold. The hysteresis comparator can improve the system stability and avoid invalid flipping of the comparator.

[0070] In one embodiment, the hysteresis comparator includes a comparator CP1, a fifth resistor R9, a sixth resistor R10 and a seventh resistor R11; specifically, a first comparison end of the comparator CP1 is electrically connected to a second end of the third resistor R7, a first end of the fifth resistor R9 is electrically connected to a second comparison end of the comparator CP1, and a second end of the fifth resistor R9 is electrically connected to an output end of the comparator CP1; a first end of the sixth resistor R10 is electrically connected to a power supply, a second end of the sixth resistor R10 and a first end of the seventh resistor R11 are electrically connected to a second comparison end of the comparator CP1, and a second end of the seventh resistor R11 is grounded.

[0071] Through the above hysteresis comparator, the hysteresis interval and They are:

[0072]

[0073] Among them, Vcc is the power supply, and its value is equal to 5V. is the first voltage comparison threshold of the hysteresis comparator, which is numerically equal to the voltage across the seventh resistor R11 after the fifth resistor R9 and the sixth resistor R10 are connected in parallel to form an equivalent resistor and then connected in series with the seventh resistor R11. is the second voltage comparison threshold of the hysteresis comparator, which is numerically equal to the voltage across the equivalent resistor formed by connecting the fifth resistor R9 and the seventh resistor R11 in parallel and then connecting the fifth resistor R9 and the seventh resistor R11 in series with the sixth resistor R10.

[0074] In one example, the resistance values ​​of the third resistor R7, the fourth resistor R8 and the fifth resistor R9 are equal to 10 kΩ, the resistance value of the sixth resistor R10 is equal to 3 kΩ, and the resistance value of the seventh resistor R11 is equal to 1 kΩ. Therefore, by substituting them into the above formula, the first voltage comparison threshold is numerically equal to 1.5 V, and the second voltage comparison threshold is numerically equal to 1.16 V. It can be further known that the first current comparison threshold The value is equal to 12mA, the second current comparison threshold The numerical value is equal to 9.28mA. That is to say, when the current signal amplitude output by the current output pin of the current signal conversion module 120 decreases to below 9.28mA, the output is flipped to a low level, and if it increases to above 12mA, the output is flipped to a high level. Therefore, in the embodiment of the present application, when the wheel speed analog signal of 14mA or 28mA flows through the wheel speed feedback acquisition module 300, a high level will be output and transmitted to the wheel speed signal receiving pin of the controller 2; when the wheel speed analog signal of 7mA flows through the wheel speed feedback acquisition module 300, a low level will be output and transmitted to the wheel speed signal receiving pin of the controller 2. The controller 2 uses the high and low levels output by the current control pin to control the current signal generating module 100 to generate a corresponding current signal. Therefore, the controller 2 can judge whether the pulse signal received by the wheel speed signal receiving pin matches the preset pulse signal according to the high and low level changes received by the wheel speed signal receiving pin, thereby realizing feedback collection of the output signal of the current signal generating module 100 and real-time detection of whether the output of the current signal generating module 100 is correct.

[0075] The wheel speed simulation circuit provided in the embodiment of the present application can realize feedback collection of wheel speed simulation signals by introducing a wheel speed feedback collection module so that the controller can perform signal diagnosis, thereby effectively ensuring the accuracy of the output of the current signal generating module.

[0076] In the real wheel speed signal acquisition circuit of a car or rail vehicle, the wheel speed simulation circuit is required to have a certain fault monitoring function. In the process of vehicle production and fault diagnosis verification, the externally connected wheel speed sensor or sensor simulation circuit is required to simulate the corresponding fault. Therefore, in order to make the wheel speed simulation circuit provided by the present application more practical, the embodiment of the present application sets a wheel speed fault simulation module 400 in the wheel speed simulation circuit 1. The wheel speed fault simulation module 400 is also electrically connected to the controller 2, and is used to simulate various types of faults that occur in the real wheel speed sensor under the control of the controller 2.

[0077] Figure 6 Schematic diagram of a circuit of a wheel speed fault simulation module provided in an embodiment of the present application.

[0078] like Figure 6 As shown, the wheel speed fault simulation module 400 includes a first switch tube Q5, an eighth resistor R12, a second switch tube Q6 and a third switch tube Q7.

[0079] The source of the first switch tube Q5 is electrically connected to the battery module, the drain of the first switch tube Q5 is electrically connected to the second switch tube Q6 and the third switch tube Q7 in sequence, and then electrically connected to the first end of the eighth resistor R12, and the speed positive signal end WSP_FL of the external speed processing circuit corresponding to the left front wheel is electrically connected between the drain of the second switch tube Q6 and the source of the third switch tube Q7; the second end of the eighth resistor R12 is grounded.

[0080] It should be noted that the above circuit structure only includes the simulated left front wheel signal. The wheel speed fault simulation module 400 may also include a switch tube Q8 and a switch tube Q9, the drain of the first switch tube Q5 is electrically connected to the switch tube Q8 and the switch tube Q9 in sequence and then electrically connected to the first end of the eighth resistor R12; the speed positive signal end WSP_FR of the external speed processing circuit corresponding to the right front wheel is electrically connected between the drain of the switch tube Q8 and the source of the switch tube Q9; the wheel speed fault simulation module 400 may also include a switch tube Q10 and a switch tube Q11, the drain of the first switch tube Q5 is electrically connected to the switch tube Q10 and the switch tube Q11 in sequence and then electrically connected to the eighth resistor R12 The first end of the eighth resistor R12 is electrically connected; the speed positive signal end WSP_RR of the external speed processing circuit corresponding to the right rear wheel is electrically connected between the drain of the switch tube Q12 and the source of the switch tube Q13.

[0081] It should be noted that the eighth resistor R12 is a current limiting resistor, and its function is to prevent the signal from being short-circuited to the ground. In an example, the resistance value of the eighth resistor R12 can be 20Ω, or other values, which are not limited in this application.

[0082] The gates of the first switch tube Q5 , the second switch tube Q6 , and the third switch tube Q7 are all electrically connected to the controller 2 , and the gates of the switch tubes Q8 to Q13 are also electrically connected to the controller 2 . Figure 5 The switch tube in the controller can be switched between on and off under the control of the controller, thereby simulating possible failures of the wheel speed sensor under different conditions. The switch tubes Q5 to Q13 can be metal-oxide-semiconductor field-effect transistors (MOSFET) or other types, and the specific type of the switch tube is not limited in this application.

[0083] Specifically, the corresponding relationship between the fault simulation and the switching of the switch tube is shown in Table 2.

[0084]

[0085] Among them, FL represents the left front wheel speed signal, FR represents the right front wheel speed signal, RL represents the left rear wheel speed signal, and RR represents the right rear wheel speed signal; in the table, 1 represents that the switch tube is turned on, and 0 represents that the switch tube is turned off.

[0086] In one embodiment, the transistors Q1 to Q3 in the current control module 110 are turned on to be in a conducting state, and the current signal generating module 100 has no current output, which can simulate a disconnection and open circuit fault of the wheel speed sensor.

[0087] In one embodiment, the first switch tube Q5 is turned on. If the second switch tube Q6 is turned on, it can simulate that the wheel speed sensor signal corresponding to the left front wheel is short-circuited to a power failure; or, if the switch tube Q8 is turned on, it can simulate that the wheel speed sensor signal corresponding to the right front wheel is short-circuited to a power failure; or, if the switch tube Q10 is turned on, it can simulate that the wheel speed sensor signal corresponding to the left rear wheel is short-circuited to a power failure; or, if the switch tube Q12 is turned on, it can simulate that the wheel speed sensor signal corresponding to the right rear wheel is short-circuited to a power failure.

[0088] In one embodiment, if the third switch tube Q7 is turned on, an overcurrent fault of the wheel speed sensor corresponding to the left front wheel can be simulated; or, if the switch tube Q9 is turned on, an overcurrent fault of the wheel speed sensor corresponding to the right front wheel can be simulated; or, if the switch tube Q11 is turned on, an overcurrent fault of the wheel speed sensor corresponding to the left rear wheel can be simulated; or, if the switch tube Q13 is turned on, an overcurrent fault of the wheel speed sensor corresponding to the right rear wheel can be simulated.

[0089] In one embodiment, any two of the switch tubes (Q6, Q8, Q10 and Q12) electrically connected to the drain of the first switch tube Q5 are turned on to simulate a short-circuit fault of the wheel speed sensor signals.

[0090] In the embodiment of the present application, a wheel speed fault simulation module is provided in the wheel speed simulation circuit, so that various fault types of the wheel speed sensor can be simulated, which is convenient for testing and fault diagnosis and debugging.

[0091] In addition, an embodiment of the present application also provides a wheel speed testing system. Figure 7 It is a structural schematic diagram of the wheel speed testing system provided in an embodiment of the present application.

[0092] like Figure 7 As shown, the wheel speed test system includes: a host computer, a controller and multiple wheel speed simulation circuits as described above; the host computer and the controller communicate through a serial port; the wheel speed simulation circuits are set one-to-one corresponding to the vehicle wheels; and the wheel speed simulation circuits are electrically connected to the controller.

[0093] In one embodiment, the host computer and the controller can communicate with each other via the RS485 serial bus protocol.

[0094] The controller includes but is not limited to a processing device such as a microprocessor or a programmable logic device.

[0095] In one example, the wheel speed signals include four channels: the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel. Accordingly, a wheel speed simulation circuit corresponding to the left front wheel, a wheel speed simulation circuit corresponding to the right front wheel, a wheel speed simulation circuit corresponding to the left rear wheel, and a wheel speed simulation circuit corresponding to the right rear wheel are set up accordingly.

[0096] The host computer is used to send the simulated wheel speed sensor type to the controller, and the controller controls the current signal generating module to generate a wheel speed simulation signal corresponding to the simulated wheel speed sensor type, and outputs it via the wheel speed output protection module.

[0097] It should be noted that each of the above wheel speed simulation circuits includes a current signal generation module and a wheel speed output protection module; in addition, it also includes a wheel speed feedback acquisition module and a wheel speed fault simulation module.

[0098] The wheel speed feedback acquisition module is used to transmit the wheel speed analog signal generated by the current signal generation module to the wheel speed signal receiving pin of the controller, so that the controller can perform signal diagnosis on the wheel speed analog signal. In one example, if the host computer sends to the controller that the type of the analog wheel speed sensor is a non-intelligent wheel speed sensor, the controller makes the current control pin output the corresponding high and low levels according to the control method shown in Table 1, and generates a current type square wave signal with a high current of 14mA, a low current of 7mA, and a duty cycle of 50% corresponding to the non-intelligent wheel speed sensor; by receiving the feedback signal output by the wheel speed feedback acquisition module, the decoding method can be determined according to the type of the analog wheel speed sensor (non-intelligent wheel speed sensor in this example), and the received feedback signal is decoded using the decoding method to parse the speed signal. When the parsed speed signal is inconsistent with the preset output signal, it can be determined that the wheel speed analog signal is wrong. The controller can report the output fault of the current signal generation module to the host computer through the serial port. The embodiment of the present application uses the feedback mechanism to enable the wheel speed simulation circuit to have a signal diagnosis function and improve the accuracy of the output signal.

[0099] In one embodiment, the host computer is further used to send a simulated fault type to the controller, and the controller controls the wheel speed fault simulation module to generate a simulated fault corresponding to the simulated fault type.

[0100] As can be seen from the above embodiments, the wheel speed simulation circuit and wheel speed test system provided by the present application control the high and low levels of the current control pin through the controller, and the current control module generates an initial current signal under the control of the current control pin, and amplifies the initial current signal through the current signal conversion module to obtain a wheel speed simulation signal, thereby simulating the signal output by the real wheel speed sensor. In the wheel speed simulation circuit provided by the present application, the circuit module for generating the wheel speed simulation signal has a simple structure and low cost, and can be accurately controlled by the controller to output current signals with different current amplitudes, thereby realizing the simulation of multiple types of wheel speed sensors, and has strong versatility. In addition, by setting a wheel speed output protection module, the simulated wheel speed signal is protected from being correctly transmitted to the external speed processing circuit; by setting a wheel speed feedback acquisition module, the feedback acquisition of the simulated wheel speed signal is realized, so that the controller performs signal diagnosis, and the accuracy of the output signal is effectively guaranteed; in addition, by setting a wheel speed fault simulation module, various fault types of the real wheel speed sensor can be simulated, which is convenient for testing and fault diagnosis and debugging; therefore, the wheel speed simulation circuit and wheel speed test system provided by the present application can realize a comprehensive wheel speed simulation.

[0101] It should be noted that the above-mentioned sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0102] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device, equipment, and storage medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0103] A person skilled in the art will appreciate that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer storage medium, and the storage medium mentioned above may be a read-only memory, a disk or an optical disk, etc.

[0104] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A wheel speed simulation circuit, characterized in that: The wheel speed simulation circuit includes a current signal generating module and a wheel speed output protection module; the wheel speed simulation circuit is electrically connected to a controller, and the current signal generating module is electrically connected to a current control pin of the controller; The current signal generating module comprises a current control module and a current signal converting module; the current control module is electrically connected to the current signal converting module; the current control module is used to generate an initial current signal under the control of the current control pin; the current signal converting module is used to amplify the initial current signal to obtain a wheel speed simulation signal, and the wheel speed simulation signal is used to simulate the signal output by the real wheel speed sensor; The wheel speed output protection module includes a voltage protection module and a rectifier bridge module; the voltage protection module is electrically connected to the current signal conversion module; the rectifier bridge module is connected in parallel with the voltage protection module, and the rectifier bridge module is used to output the wheel speed analog signal to an external speed processing circuit.

2. The wheel speed simulation circuit according to claim 1, characterized in that: The current control module includes a first current control circuit, a second current control circuit and a third current control circuit; the current control pins include a first current control pin, a second current control pin and a third current control pin; the first current control circuit generates a first initial current signal under the control of the first current control pin; the second current control circuit generates a second initial current signal under the control of the second current control pin; the third current control circuit generates a third initial current signal under the control of the third current control pin; the first initial current signal is used to simulate a low level output by multiple types of real wheel speed sensors, the second initial current signal and the third initial current signal are combined to simulate a high level output by multiple types of real wheel speed sensors, and the current value of the third initial current signal is greater than the current value of the second initial current signal.

3. The wheel speed simulation circuit according to claim 2, characterized in that: The first current control circuit includes a first transistor, a first resistor, a second resistor and a first diode; The first end of the first resistor is electrically connected to the reference voltage output pin of the current signal conversion module, and the cathode of the first diode is electrically connected to the current input pin of the current signal conversion module; the second end of the first resistor is electrically connected to the anode of the first diode and the collector of the first transistor, the base of the first transistor is electrically connected to the first end of the second resistor, the emitter of the first transistor is grounded, and the second end of the second resistor is electrically connected to the first current control pin.

4. The wheel speed simulation circuit according to claim 1, characterized in that: The voltage protection module includes a capacitor and a transient suppression diode; The first end of the capacitor is electrically connected to the power supply pin of the current signal conversion module, and the second end of the capacitor is electrically connected to the current output pin of the current signal conversion module; the transient suppression diode and the capacitor form a parallel structure.

5. The wheel speed simulation circuit according to claim 1, characterized in that: The rectifier bridge module includes a second diode, a third diode, a fourth diode and a fifth diode; the cathode of the second diode and the cathode of the fourth diode are both electrically connected to the power supply pin of the current signal conversion module, the anode of the third diode and the anode of the fifth diode are both electrically connected to the current output pin, the cathode of the third diode is electrically connected to the anode of the second diode, and the cathode of the fifth diode is electrically connected to the anode of the fourth diode; a first signal terminal is led out at the anode of the second diode, and a second signal terminal is led out at the cathode of the fifth diode; The first signal terminal is electrically connected to the speed positive signal terminal, and the second signal terminal is electrically connected to the speed negative signal terminal; or, The first signal terminal is electrically connected to the speed negative signal terminal, and the second signal terminal is electrically connected to the speed positive signal terminal; the speed positive signal terminal is one end of the external speed processing circuit, and the speed positive signal terminal is used to provide voltage to the wheel speed simulation circuit; the speed negative signal terminal is the other end of the external speed processing circuit, and the speed negative signal terminal is used to receive the wheel speed simulation signal generated by the wheel speed simulation circuit.

6. The wheel speed simulation circuit according to claim 1, characterized in that: The controller includes a wheel speed signal receiving pin, and the wheel speed simulation circuit also includes a wheel speed feedback acquisition module. The wheel speed signal receiving pin is electrically connected to the current signal generating module through the wheel speed feedback acquisition module. The wheel speed feedback acquisition module is used to transmit the wheel speed simulation signal to the wheel speed signal receiving pin so that the controller performs signal diagnosis on the wheel speed simulation signal.

7. The wheel speed simulation circuit according to claim 6, characterized in that: The wheel speed feedback acquisition module includes an operational amplifier, a third resistor, a fourth resistor and a hysteresis comparator; The non-inverting input terminal of the operational amplifier is electrically connected to the current output pin of the current signal conversion module, and the inverting input terminal of the operational amplifier is electrically connected to the reference ground pin of the current signal conversion module; the output terminal of the operational amplifier is electrically connected to the first end of the third resistor, the second end of the third resistor is electrically connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded; The output end of the hysteresis comparator is electrically connected to the wheel speed signal receiving pin, the input of the first comparison end of the hysteresis comparator is the voltage divided by the third resistor and the fourth resistor; the input of the second comparison end of the hysteresis comparator is the reference voltage.

8. The wheel speed simulation circuit according to claim 7, characterized in that: The hysteresis comparator comprises a comparator, a fifth resistor, a sixth resistor and a seventh resistor; The first comparison terminal of the comparator is electrically connected to the second terminal of the third resistor, the first terminal of the fifth resistor is electrically connected to the second comparison terminal of the comparator, and the second terminal of the fifth resistor is electrically connected to the output terminal of the comparator; The first end of the sixth resistor is electrically connected to the power supply, the second end of the sixth resistor and the first end of the seventh resistor are electrically connected to the second comparison end of the comparator, and the second end of the seventh resistor is grounded.

9. The wheel speed simulation circuit according to claim 1, characterized in that: The wheel speed simulation circuit further includes a wheel speed fault simulation module, which is electrically connected to the controller and is used to simulate a fault occurring in the wheel speed sensor under the control of the controller; The wheel speed fault simulation module includes a first switch tube, an eighth resistor, a second switch tube and a third switch tube; The source of the first switch tube is electrically connected to the battery module, the drain of the first switch tube is electrically connected to the second switch tube and the third switch tube in sequence, and then electrically connected to the first end of the eighth resistor, and the speed positive signal end of the external speed processing circuit is electrically connected between the drain of the second switch tube and the source of the third switch tube; the second end of the eighth resistor is grounded; The gates of the first switch tube, the second switch tube, and the third switch tube are all electrically connected to the controller.

10. A wheel speed testing system, characterized in that: The wheel speed test system comprises: a host computer, a controller and a plurality of wheel speed simulation circuits as described in any one of claims 1 to 9; the host computer and the controller communicate via a serial port; the wheel speed simulation circuits are arranged in a one-to-one correspondence with the vehicle wheels; the wheel speed simulation circuits are electrically connected to the controller; The host computer is used to send the simulated wheel speed sensor type to the controller, and the controller controls the current signal generating module to generate a wheel speed simulation signal corresponding to the simulated wheel speed sensor type, and outputs it via the wheel speed output protection module.

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