Wheel speed sensor analog circuit and analog sampling circuit

Abstract

The application discloses a wheel speed sensor simulation circuit and a simulation sampling circuit. The wheel speed sensor simulation circuit comprises a signal generation circuit and a fault injection circuit; the signal generation circuit comprises a switch module and a resistance module; the switch module is connected with the resistance module, the resistance module is connected with an input end of the fault injection circuit, and an output end of the fault injection circuit is used for being connected with a sampling resistor in the sampling circuit; wherein the switch module is used for adjusting the resistance value of the resistance module, so as to change the voltage of the sampling resistor; and the fault injection circuit is used for injecting an electrical fault signal to the sampling circuit, so as to simulate the electrical fault of the wheel speed sensor.

Description

Technical Field

[0001] This application relates to the field of vehicle perception technology, specifically to a wheel speed sensor analog circuit and an analog sampling circuit. Background Technology

[0002] Anti-lock Braking System (ABS) and Electronic Stability Control (ESC) are crucial components of automotive safety. Wheel speed sensors are key components in the operation of ABS and ESC systems, responsible for providing wheel status information. Therefore, wheel speed sensor signals are essential input signals for functional and bench testing during the development of these systems. Generating wheel speed signals by constructing a real-world environment for functional and bench testing has drawbacks such as being time-consuming, costly, and creating a complex system that is difficult to maintain, making it unsuitable for testing in a laboratory environment.

[0003] In related technologies, a current-output type wheel speed sensor signal simulation circuit has been proposed based on the characteristics of wheel speed sensor signals and the working principle of its analytical circuit. However, the related technologies have the following problems: 1. The circuits in the related technologies cannot simulate common electrical faults; 2. The wheel speed sensor signals simulated by the circuits in the related technologies are not comprehensive. Summary of the Invention

[0004] In view of this, embodiments of this application provide at least one wheel speed sensor analog circuit and an analog sampling circuit.

[0005] The technical solution of this application embodiment is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a wheel speed sensor analog circuit, which includes a signal generation circuit and a fault injection circuit; the signal generation circuit includes a switching module and a resistor module.

[0007] The switch module is connected to the resistor module, the resistor module is connected to the input of the fault injection circuit, and the output of the fault injection circuit is connected to the sampling resistor in the sampling circuit; wherein,

[0008] The switching module is used to adjust the resistance value of the resistor module in order to change the voltage across the sampling resistor.

[0009] The fault injection circuit is used to inject electrical fault signals into the sampling circuit to simulate electrical faults in the wheel speed sensor.

[0010] In this embodiment, the signal generation circuit in the wheel speed sensor simulation circuit includes a switching module and a resistor module. The switching module is connected to the resistor module, and the resistor module is connected to the input terminal of the fault injection circuit. The output terminal of the fault injection circuit in the wheel speed sensor simulation circuit is connected to the sampling resistor in the sampling circuit. The switching module is used to adjust the resistance value of the resistor module to change the voltage across the sampling resistor. The fault injection circuit is used to inject electrical fault signals into the sampling circuit to simulate electrical faults in the wheel speed sensor. By adjusting the resistance value of the resistor module through the switching module, the voltage across the sampling resistor changes, thereby simulating different current signals from the wheel speed sensor under various scenarios, thus improving the comprehensiveness of the simulated wheel speed sensor signal. Simultaneously, by injecting different electrical fault signals into the sampling circuit through the fault injection circuit, various electrical faults of the wheel speed sensor can be simulated. Compared to waiting for natural faults to occur during actual vehicle operation for testing, the fault injection circuit can actively and quickly simulate various electrical faults in a laboratory environment, greatly shortening the testing cycle. Furthermore, by precisely controlling the type of electrical fault and the injection timing, testing can be performed more efficiently, reducing testing costs.

[0011] In some embodiments, the switching module includes multiple switching units, and the resistor module includes multiple resistor units, with the number of switching units corresponding to the number of resistor units; wherein, the switching units and the corresponding resistor units are connected in series to form a signal generation branch; the multiple signal generation branches are connected in parallel and then connected to the input terminal of the fault injection circuit.

[0012] In this embodiment, the switching module includes multiple switching units, and the resistor module includes multiple resistor units, with the number of switching units corresponding to the number of resistor units. Each switching unit is connected in series with its corresponding resistor unit to form a signal generation branch. Multiple signal generation branches are connected in parallel and then connected to the input terminal of the fault injection circuit. This allows for the connection of resistor units within the same signal generation branch to the circuit by closing a switching unit, thereby changing the resistance of the resistor module and simulating different current signals from the wheel speed sensor. Thus, different current signals from the wheel speed sensor can be simulated using a simple circuit, reducing the complexity of the analog circuit.

[0013] In some embodiments, the switching unit is a transistor; the wheel speed sensor analog circuit further includes a control module; wherein, for each signal generation branch, the collector of the transistor in the signal generation branch is connected to the corresponding resistor unit, the emitter of the transistor in the signal generation branch is connected to the first power supply, and the base of the transistor in the signal generation branch is connected to the control port of the control module.

[0014] In this embodiment, the switching unit of each signal generation branch is a transistor. The collector of the transistor in each signal generation branch is connected to the corresponding resistor unit, the emitter of the transistor is connected to the first power supply, and the base of the transistor is connected to the control port of the control module. In this way, the control module can control the transistor's on / off state, allowing the resistor unit corresponding to the switching unit to be connected to or disconnected from the wheel speed sensor analog circuit, thereby improving the accuracy of the current signal from the simulated wheel speed sensor.

[0015] In some embodiments, the plurality of resistor units include a first resistor unit, a second resistor unit, a third resistor unit, and a fourth resistor unit with sequentially increasing resistance; the plurality of switch units include a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit; wherein, the collector of the first switch unit is connected to the first resistor unit, the emitter of the first switch unit is connected to a first power supply, and the base of the first switch unit is connected to a first control port of the control module; the collector of the second switch unit is connected to the second resistor unit, the emitter of the second switch unit is connected to the first power supply, and the base of the second switch unit is connected to a second control port of the control module; the collector of the third switch unit is connected to the third resistor unit, the emitter of the third switch unit is connected to the first power supply, and the base of the third switch unit is connected to a third control port of the control module; the collector of the fourth switch unit is connected to the fourth resistor unit, the emitter of the fourth switch unit is connected to the first power supply, and the base of the fourth switch unit is connected to a fourth control port of the control module.

[0016] In this embodiment, multiple resistor units include a first resistor unit, a second resistor unit, a third resistor unit, and a fourth resistor unit with sequentially increasing resistance; multiple switch units include a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit; the bases of the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are respectively connected to different control ports of the control module. Thus, by outputting control signals through the corresponding control ports of the control module, the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit can be turned on or off, thereby enabling the first resistor unit, the second resistor unit, the third resistor unit, and the fourth resistor unit to be connected to or disconnected from the wheel speed sensor analog circuit, thereby improving the accuracy of the analog current signal.

[0017] In some embodiments, when the first, second, third, and fourth switching units are all open, the voltage of the sampling resistor is 0; when the first, second, and third switching units are all open and the fourth switching unit is closed, the voltage of the sampling resistor is a first voltage; when the first, second, and fourth switching units are all open and the third switching unit is closed, the voltage of the sampling resistor is a second voltage; when the first, fourth, and third switching units are all open and the second switching unit is closed, the voltage of the sampling resistor is a third voltage; and when the fourth, second, and third switching units are all open and the first switching unit is closed, the voltage of the sampling resistor is a fourth voltage; wherein the first, second, third, and fourth voltages increase sequentially.

[0018] In this embodiment, by turning on the corresponding switching unit and turning off other switching units, the corresponding sampling resistor can be controlled to be connected to the circuit, thereby improving the accuracy of the analog current signal.

[0019] In some embodiments, the fault injection circuit includes a fifth switching unit; the first end of the fifth switching unit is connected to the resistor module, and the second end of the fifth switching unit is used to connect to the sampling resistor.

[0020] In this embodiment, by connecting a fifth switching unit in series between the signal generation circuit and the sampling circuit, the open circuit fault of the wheel speed sensor in reality can be simulated by disconnecting the fifth switching unit.

[0021] In some embodiments, the fault injection circuit further includes a sixth switching unit; the first end of the sixth switching unit is connected to the second end of the fifth switching unit, the first end of the sixth switching unit is also used to connect to a sampling resistor, and the second end of the sixth switching unit is connected to a second power supply.

[0022] In this embodiment, a sixth switching unit is provided between the fifth switching unit and the sampling circuit. The sixth switching unit is connected to the second power supply, so that when the fifth switching unit is open and the sixth switching unit is closed, the situation of a wheel speed sensor short-circuiting to the power supply in reality can be simulated.

[0023] In some embodiments, the fault injection circuit further includes a seventh switching unit; the first end of the seventh switching unit is connected to the second end of the fifth switching unit, and the second end of the seventh switching unit is connected to the ground terminal of the second power supply.

[0024] In this embodiment, a seventh switching unit is provided between the sixth switching unit and the sampling circuit, and the seventh switching unit is grounded. Thus, when the fifth and sixth switching units are open and the seventh switching unit is closed, a short circuit to ground in a real-world wheel speed sensor situation can be simulated.

[0025] Secondly, embodiments of this application provide an analog sampling circuit, which includes a wheel speed sensor analog circuit and a sampling circuit. The wheel speed sensor analog circuit includes a signal generation circuit and a fault injection circuit. The signal generation circuit includes a switch module and a resistor module. The switch module is connected to the resistor module, the resistor module is connected to the input terminal of the fault injection circuit, and the output terminal of the fault injection circuit is connected to the sampling circuit. The switch module is used to adjust the resistance value of the resistor module to change the voltage of the sampling resistor in the sampling circuit. The fault injection circuit is used to inject an electrical fault signal into the sampling circuit to simulate an electrical fault in the wheel speed sensor. It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and not intended to limit the technical solutions of this application.

[0026] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this application. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the technical solutions of this application.

[0028] Figure 1 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 1 ;

[0029] Figure 2 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 2 ;

[0030] Figure 3 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 3 ;

[0031] Figure 4 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 4 ;

[0032] Figure 5 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 5 ;

[0033] Figure 6A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 6 ;

[0034] Figure 7 A schematic diagram of the structure of a wheel speed sensor analog circuit provided in this application embodiment. Figure 7 ;

[0035] Figure 8 This is a schematic diagram illustrating the relationship between switch state and voltage, provided in an embodiment of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application are further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0038] The terms “first / second / third” are used merely to distinguish similar vehicles and do not represent a specific ordering of vehicles. It is understood that “first / second / third” may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in a sequence other than that illustrated or described herein.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this application.

[0040] Anti-lock Braking System (ABS) and Electronic Stability Control (ESC) are crucial components of vehicle safety. Wheel speed sensors are key components in the operation of ABS and ESC systems, responsible for providing wheel status information. Therefore, wheel speed sensor signals are essential input signals for functional testing and bench testing during the development of these systems.

[0041] In functional and bench testing, generating wheel speed signals by building a real-world environment has drawbacks such as time consumption, high cost, and complex system that is difficult to maintain, making it unsuitable for testing in a laboratory environment. Therefore, based on the characteristics of wheel speed sensor signals and the working principle of their analytical circuits, related technologies have proposed a series of current-output wheel speed sensor signal simulation circuits, overcoming the shortcomings of building a real-world environment while meeting basic testing requirements. However, the solutions in these technologies have the following technical problems: 1. The solutions in these technologies do not have the function of injecting common electrical faults (short circuit to power supply, short circuit to ground, open circuit); 2. They do not consider the generation of fault currents (such as the typical value of 3.5mA for TLE5046) of high-end current wheel speed sensors with functional safety mechanisms, and can only generate all or part of the output currents of conventional wheel speed sensors (7mA, 14mA, 28mA); 3. Most current signal generation circuits are relatively complex.

[0042] To address the aforementioned technical problems, embodiments of this application provide a wheel speed sensor analog circuit, such as... Figure 1 As shown, the wheel speed sensor analog circuit 100 includes a signal generation circuit 101 and a fault injection circuit 102; the signal generation circuit 101 includes a switch module 1011 and a resistor module 1012.

[0043] The switch module 1011 is connected to the resistor module 1012, the resistor module 1012 is connected to the input terminal of the fault injection circuit 102, and the output terminal of the fault injection circuit 102 is used to connect to the sampling resistor 201 in the sampling circuit 200; wherein,

[0044] The switching module 1011 is used to adjust the resistance value of the resistor module 1012 to change the voltage of the sampling resistor 201;

[0045] The fault injection circuit 102 is used to inject an electrical fault signal into the sampling circuit 200 to simulate an electrical fault in the wheel speed sensor.

[0046] In this embodiment, when the fault injection circuit is connected to the sampling resistor, the resistor module in the signal generation circuit and the sampling resistor are in series. When the switch module is adjusted, the resistance value of the resistor module will change, which will cause the voltage across the resistor module to change accordingly. Since the total voltage across the resistor module and the sampling resistor is constant, the voltage across the sampling resistor will also change, and the current through the sampling resistor will also change accordingly, thereby simulating different current signals of the wheel speed sensor.

[0047] In this embodiment, the switching module includes different switching units, which are connected to resistors with different or the same resistance values. By turning on different switching units, resistors with different resistance values ​​are connected to the sampling resistor, thereby simulating different current signals from the wheel speed sensor.

[0048] In some embodiments, different resistors are connected in parallel. When it is necessary to simulate the first current signal of the wheel speed sensor, the switching unit of at least one resistor corresponding to the first current signal can be turned on, and the switching units of other resistors can be turned off, thereby realizing the adjustment of the resistance value of the resistor module through the switching module to change the voltage of the sampling resistor 201.

[0049] In this embodiment, the fault injection circuit includes multiple fault injection branches, each used to simulate electrical faults in different wheel speed sensors. For example, the electrical fault may include at least one of the following: an open-circuit fault, a short-circuit to power supply fault, and a short-circuit to ground fault.

[0050] Understandably, wheel speed sensors will not only output different current signals according to different actual scenarios during actual operation, but will also generate various electrical faults. Therefore, when simulating the output signal of the wheel speed sensor, it is also necessary to simulate the electrical faults of the wheel speed sensor.

[0051] In this embodiment, the signal generation circuit in the wheel speed sensor simulation circuit includes a switching module and a resistor module. The switching module is connected to the resistor module, and the resistor module is connected to the input terminal of the fault injection circuit. The output terminal of the fault injection circuit in the wheel speed sensor simulation circuit is connected to the sampling resistor in the sampling circuit. The switching module is used to adjust the resistance value of the resistor module to change the voltage across the sampling resistor. The fault injection circuit is used to inject electrical fault signals into the sampling circuit to simulate electrical faults in the wheel speed sensor. By adjusting the resistance value of the resistor module through the switching module, the voltage across the sampling resistor changes, thereby simulating different current signals from the wheel speed sensor under various scenarios, thus improving the comprehensiveness of the simulated wheel speed sensor signal. Simultaneously, by injecting different electrical fault signals into the sampling circuit through the fault injection circuit, various electrical faults of the wheel speed sensor can be simulated. Compared to waiting for natural faults to occur during actual vehicle operation for testing, the fault injection circuit can actively and quickly simulate various electrical faults in a laboratory environment, greatly shortening the testing cycle. Furthermore, by precisely controlling the type of electrical fault and the injection timing, testing can be performed more efficiently, reducing testing costs.

[0052] In some embodiments, such as Figure 2 As shown, the switching module includes multiple switching units 10111 ( Figure 2The number of switch units shown is 2), and the resistor module includes multiple resistor units 10121 ( Figure 2 The number of resistor units shown is 2), and the number of switch units 10111 corresponds to the number of resistor units 10121; wherein, the switch units 10111 and the corresponding resistor units 10121 are connected in series to form a signal generation branch; multiple signal generation branches are connected in parallel and then connected to the input terminal of the fault injection circuit 102.

[0053] Here, the number of switching units corresponds to the number of resistor units; it can mean that multiple switching units correspond one-to-one with multiple resistor units, for example... Figure 2 The diagram shows two switching units and two resistor units, with each switching unit corresponding to one resistor unit. This means that each signal generation branch has one switching unit and one resistor unit connected in series. In some embodiments, the number of switching units corresponds to the number of resistor units; alternatively, one switching unit may correspond to at least two resistor units, meaning that each signal generation branch has one switching unit and at least two resistor units connected in series.

[0054] In this embodiment, the signal generation circuit includes multiple signal generation branches connected in parallel. Each signal generation branch has a switch unit and a resistor unit connected in series, and the control terminal of the switch unit is connected to the control module. That is, the control module can control the closing and opening of the switch unit in each signal generation branch.

[0055] In this embodiment, the resistor unit to be turned on in the resistor module can be determined based on the magnitude of the current signal from the wheel speed sensor to be simulated. It is understood that the resistor module is connected in series with the sampling resistor. When different resistor units in the resistor module are turned on, the voltage across the sampling resistor will change accordingly, thus changing the current flowing through the sampling resistor. Therefore, the current signal from the wheel speed sensor can be simulated using the current flowing through the sampling resistor.

[0056] In some embodiments, depending on the magnitude of the current signal from the wheel speed sensor to be simulated, one resistor unit of a signal generation branch can be selected to be activated, or multiple resistor units of signal generation branches can be activated. This application embodiment does not limit the number of signal generation branches corresponding to the resistor unit activated each time.

[0057] In this embodiment, the switching module includes multiple switching units, and the resistor module includes multiple resistor units, with the number of switching units corresponding to the number of resistor units. Each switching unit is connected in series with its corresponding resistor unit to form a signal generation branch. Multiple signal generation branches are connected in parallel and then connected to the input terminal of the fault injection circuit. This allows for the connection of resistor units within the same signal generation branch to the circuit by closing a switching unit, thereby changing the resistance of the resistor module and simulating different current signals from the wheel speed sensor. Thus, different current signals from the wheel speed sensor can be simulated using a simple circuit, reducing the complexity of the analog circuit.

[0058] In some embodiments, the switching unit is a transistor; the wheel speed sensor analog circuit further includes a control module; wherein, for each signal generation branch, the collector of the transistor in the signal generation branch is connected to the corresponding resistor unit, the emitter of the transistor in the signal generation branch is connected to the first power supply, and the base of the transistor in the signal generation branch is connected to the control port of the control module.

[0059] In this embodiment, the switching unit is a controllable transistor. The control module transmits a control signal to the base of the transistor, causing the emitter and collector of the transistor to conduct, thereby connecting the resistor unit corresponding to the switching unit to the wheel speed sensor analog circuit.

[0060] In some embodiments, the transistors of different signal generation branches are connected to different control ports of the control module, so that the control module controls the corresponding transistors to conduct through the corresponding control ports.

[0061] In this embodiment, the switching unit of each signal generation branch is a transistor. The collector of the transistor in each signal generation branch is connected to the corresponding resistor unit, the emitter of the transistor is connected to the first power supply, and the base of the transistor is connected to the control port of the control module. In this way, the control module can control the transistor's on / off state, allowing the resistor unit corresponding to the switching unit to be connected to or disconnected from the wheel speed sensor analog circuit, thereby improving the accuracy of the current signal from the simulated wheel speed sensor.

[0062] In some embodiments, such as Figure 3 As shown, the plurality of resistor units include a first resistor unit 10122, a second resistor unit 10123, a third resistor unit 10124, and a fourth resistor unit 10125 with sequentially increasing resistance; the plurality of switch units include a first switch unit 10112, a second switch unit 10113, a third switch unit 10114, and a fourth switch unit 10115; wherein,

[0063] The collector of the first switching unit 10112 is connected to the first resistor unit 10122, the emitter of the first switching unit 10112 is connected to the first power supply 104, and the base of the first switching unit 10112 is connected to the first control port of the control module 103.

[0064] The collector of the second switching unit 10113 is connected to the second resistor unit 10123, the emitter of the second switching unit 10113 is connected to the first power supply 104, and the base of the second switching unit 10123 is connected to the second control port of the control module 103.

[0065] The collector of the third switching unit 10114 is connected to the third resistor unit 10124, the emitter of the third switching unit 10114 is connected to the first power supply 104, and the base of the third switching unit 10114 is connected to the third control port of the control module 103.

[0066] The collector of the fourth switching unit 10115 is connected to the fourth resistor unit 10125, the emitter of the fourth switching unit 10115 is connected to the first power supply 104, and the base of the fourth switching unit 10115 is connected to the fourth control port of the control module 103.

[0067] In this embodiment, by analyzing the output characteristics of existing current-type wheel speed sensors, it is determined that the current signal of the current-type wheel speed sensor includes at least four current signals, such as 3.5mA, 7mA, 14mA, and 28mA. The sampling resistor in the sensor signal analysis circuit performs current-to-voltage conversion before analysis; therefore, it is necessary to generate a voltage waveform identical to the wheel speed sensor signal across the sampling resistor to simulate the real wheel speed sensor signal. To simulate at least four current signals from the current-type wheel speed sensor, the resistor module in this embodiment includes a first resistor unit, a second resistor unit, a third resistor unit, and a fourth resistor unit with sequentially increasing resistance. When a corresponding current signal needs to be simulated, the corresponding resistor unit can be turned on.

[0068] In some embodiments, the first resistor unit, the second resistor unit, the third resistor unit, and the fourth resistor unit may each be composed of one or more resistors.

[0069] In this embodiment, based on the current signal from the actual wheel speed sensor, one or more of the first, second, third, and fourth resistor units can be turned on.

[0070] In this embodiment, multiple resistor units include a first resistor unit, a second resistor unit, a third resistor unit, and a fourth resistor unit with sequentially increasing resistance; multiple switch units include a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit; the bases of the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are respectively connected to different control ports of the control module. Thus, by outputting control signals through the corresponding control ports of the control module, the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit can be turned on or off, thereby enabling the first resistor unit, the second resistor unit, the third resistor unit, and the fourth resistor unit to be connected to or disconnected from the wheel speed sensor analog circuit, thereby improving the accuracy of the analog current signal.

[0071] In some embodiments, when the first switching unit, the second switching unit, the third switching unit, and the fourth switching unit are all disconnected, the voltage of the sampling resistor is 0.

[0072] When the first switch unit, the second switch unit, and the third switch unit are all open, and the fourth switch unit is all closed, the voltage of the sampling resistor is the first voltage.

[0073] When the first switch unit, the second switch unit, and the fourth switch unit are all open, and the third switch unit is all closed, the voltage of the sampling resistor is the second voltage.

[0074] When the first switch unit, the fourth switch unit, and the third switch unit are all open, and the second switch unit is all closed, the voltage of the sampling resistor is the third voltage.

[0075] When the fourth switch unit, the second switch unit, and the third switch unit are all open, and the first switch unit is all closed, the voltage of the sampling resistor is the fourth voltage.

[0076] Among them, the first voltage, the second voltage, the third voltage, and the fourth voltage increase sequentially.

[0077] For example, with a sampling resistor value of 50Ω, a first power supply voltage of 5V, a first resistor unit value of 128Ω, a second resistor unit value of 307Ω, a third resistor unit value of 664Ω, and a fourth resistor unit value of 1378Ω, the switching states of the first, second, third, and fourth switching units, along with the circuit current and the voltage across the sampling resistor, are shown in Table 1. The relationship between the switching states of the switching units and the voltage is detailed in [reference needed]. Figure 8The current signal from the wheel speed sensor can be simulated by controlling the on and off states of the first, second, third, and fourth switching units.

[0078] Table 1

[0079]

[0080]

[0081] Wherein, 0.175V is the first voltage, 0.35V is the second voltage, 0.7V is the third voltage, and 1.4V is the fourth voltage.

[0082] In the above example, when the first, second, and third switch units are all open and the fourth switch unit is all closed, the fourth resistor unit is connected to the wheel speed sensor analog circuit. The total resistance of the wheel speed sensor analog circuit is the total resistance of the fourth resistor unit and the sampling resistor, i.e., 1378Ω + 50Ω = 1408Ω. The voltage of the first power supply is 5V, i.e., the current value corresponding to the sampling resistor is 5V / 1408Ω = 3.5mA, and the voltage value corresponding to the sampling resistor is 3.5mA * 50Ω = 0.175V.

[0083] With the first, second, and fourth switch units all open and the third switch unit all closed, the third resistor unit is connected to the wheel speed sensor analog circuit. The total resistance of the wheel speed sensor analog circuit is the total resistance of the third resistor unit and the sampling resistor, i.e., 664Ω + 50Ω = 714Ω. The voltage of the first power supply is 5V, i.e., the current corresponding to the sampling resistor is 5V / 714Ω = 7mA, and the voltage corresponding to the sampling resistor is 7mA * 50Ω = 0.35V.

[0084] With the first, fourth, and third switch units all open and the second switch units all closed, the second resistor unit is connected to the wheel speed sensor analog circuit. The total resistance of the wheel speed sensor analog circuit is the total resistance of the second resistor unit and the sampling resistor, i.e., 307Ω + 50Ω = 357Ω. The voltage of the first power supply is 5V, i.e., the current corresponding to the sampling resistor is 5V / 357Ω = 14mA, and the voltage corresponding to the sampling resistor is 14mA * 50Ω = 0.7V.

[0085] With the fourth, second, and third switch units all open and the first switch unit all closed, the first resistor unit is connected to the wheel speed sensor analog circuit. The total resistance of the wheel speed sensor analog circuit is the total resistance of the first resistor unit and the sampling resistor, i.e., 128Ω + 50Ω = 178Ω. The voltage of the first power supply is 5V, i.e., the current corresponding to the sampling resistor is 5V / 178Ω = 28mA, and the voltage corresponding to the sampling resistor is 28mA * 50Ω = 1.4V.

[0086] In this embodiment, by turning on the corresponding switching unit and turning off other switching units, the corresponding sampling resistor can be controlled to be connected to the circuit, thereby improving the accuracy of the analog current signal.

[0087] In some embodiments, such as Figure 4 As shown, the fault injection circuit 102 includes a fifth switching unit 1021; the first end of the fifth switching unit 1021 is connected to the resistor module 1012, and the second end of the fifth switching unit 1021 is used to connect to the sampling resistor 201.

[0088] In this embodiment, when the fifth switch unit is disconnected, the sampling circuit is in an open circuit state, and the voltage and current of the sampling resistor are 0, thereby simulating the situation where the wheel speed sensor has an open circuit fault in reality.

[0089] In this embodiment, by connecting a fifth switching unit in series between the signal generation circuit and the sampling circuit, the open circuit fault of the wheel speed sensor in reality can be simulated by disconnecting the fifth switching unit.

[0090] In some embodiments, such as Figure 5 As shown, the fault injection circuit further includes a sixth switching unit 1022; the first end of the sixth switching unit 1022 is connected to the second end of the fifth switching unit 1021, and the first end of the sixth switching unit 1022 is also used to connect to the sampling resistor 201; the second end of the sixth switching unit 1022 is connected to the second power supply 1023.

[0091] In this embodiment, when the fifth switch unit is open and the sixth switch unit is closed, the sampling resistor is short-circuited to the power supply, thereby simulating the situation where the wheel speed sensor is short-circuited to the power supply in reality.

[0092] In this embodiment, a sixth switching unit is provided between the fifth switching unit and the sampling circuit. The sixth switching unit is connected to the second power supply, so that when the fifth switching unit is open and the sixth switching unit is closed, the situation of a wheel speed sensor short-circuiting to the power supply in reality can be simulated.

[0093] In some embodiments, such as Figure 6 As shown, the fault injection circuit further includes a seventh switch unit 1024; the first end of the seventh switch unit 1024 is connected to the second end of the fifth switch unit 1021, and the second end of the seventh switch unit 1024 is connected to the grounding terminal of the second power supply.

[0094] In this embodiment, when the fifth switch unit is open, the sixth switch unit is open, and the seventh switch unit is closed, the sampling resistor is in a short-circuit to ground state, thereby simulating the situation where the wheel speed sensor is short-circuited to ground in reality.

[0095] In this embodiment, a seventh switching unit is provided between the sixth switching unit and the sampling circuit, and the seventh switching unit is grounded. Thus, when the fifth and sixth switching units are open and the seventh switching unit is closed, a short circuit to ground in a real-world wheel speed sensor situation can be simulated.

[0096] In some embodiments, when the fifth, sixth, and seventh switching units are all open, the fault injection circuit injects an open-circuit fault signal into the sampling circuit; when the fifth and seventh switching units are open and the sixth switching unit is on, the fault injection circuit injects a first short-circuit signal into the sampling circuit; the first short-circuit signal is used to characterize that the sampling circuit is in a short-circuit to power supply fault; when the fifth, sixth, and seventh switching units are open and the seventh switching unit is on, the fault injection circuit injects a first short-circuit signal into the sampling circuit; the first short-circuit signal is used to characterize that the sampling circuit is in a short-circuit to ground fault.

[0097] In this embodiment of the application, the power supply terminal of the second power source (i.e. Figure 6 The VBAT terminal in the middle, and the ground terminal (i.e. Figure 6 The GND terminal of the circuit is connected to the wheel speed signal acquisition controller. The wheel speed signal acquisition controller includes the sampling circuit mentioned above. The sampling circuit includes a sampling resistor and a signal processing circuit. The current signal of the fault injection circuit is transmitted to the wheel speed signal acquisition controller. The wheel speed signal acquisition controller converts the current signal into a voltage signal (i.e., the voltage across the sampling resistor) through the sampling resistor. Then, the voltage signal is adaptively processed by the signal processing circuit.

[0098] In this embodiment, when the fifth switch unit is closed and both the sixth and seventh switch units are open, the fault injection circuit does not inject any electrical fault signal into the wheel speed signal acquisition controller. At this time, the wheel speed signal acquisition controller can acquire the voltage signal corresponding to the current signal to be simulated. When the fifth switch unit is open, and both the sixth and seventh switch units are open, the fault injection circuit injects an open-circuit fault signal into the wheel speed signal acquisition controller. Because the circuit is open, the fault injection circuit does not output a current signal to the wheel speed signal acquisition controller; that is, the open-circuit fault signal indicates that the wheel speed signal acquisition controller has not received a current signal. When the fifth switch unit is open, and the sixth switch unit is closed, and the seventh switch unit is open, the sampling resistor is connected to the second power supply. The fault injection circuit injects a first short-circuit signal into the wheel speed signal acquisition controller. This first short-circuit signal represents the power supply current value of the second power supply. The voltage of the sampling resistor acquired by the wheel speed signal acquisition controller is the power supply voltage of the second power supply. When the fifth switch unit is open, and the sixth switch unit is open and the seventh switch unit is closed, the sampling resistor is connected to the ground terminal of the second power supply. At this time, the fault injection circuit injects a second short-circuit signal into the wheel speed signal acquisition controller. This second short-circuit signal represents a 0A current signal, and the wheel speed signal acquisition controller acquires a voltage of 0V from the sampling resistor.

[0099] In some embodiments, the correspondence between the switching states of the fifth, sixth, and seventh switching units and the fault injection is shown in Table 2:

[0100] Table 2

[0101]

[0102] This application embodiment also provides an analog sampling circuit, the analog acquisition circuit including a wheel speed sensor analog circuit and a sampling circuit; the wheel speed sensor analog circuit includes a signal generation circuit and a fault injection circuit; the signal generation circuit includes a switching module and a resistor module;

[0103] The switch module is connected to the resistor module, the resistor module is connected to the input terminal of the fault injection circuit, and the output terminal of the fault injection circuit is connected to the sampling circuit; wherein,

[0104] The switching module is used to adjust the resistance value of the resistor module to change the voltage of the sampling resistor in the sampling circuit.

[0105] The fault injection circuit is used to inject an electrical fault signal into the sampling circuit to simulate an electrical fault in the wheel speed sensor.

[0106] The following describes the application of the vehicle perception method provided in this application in real-world scenarios:

[0107] Anti-lock Braking System (ABS) and Electronic Stability Control (ESC) are crucial components of vehicle safety. Wheel speed sensors are key components in the operation of ABS and ESC systems, responsible for providing wheel status information. Therefore, wheel speed sensor signals are essential input signals for functional testing and bench testing during the development of these systems.

[0108] In functional and bench testing, generating wheel speed signals by building a real-world environment has drawbacks such as time consumption, high cost, and complex system that is difficult to maintain, making it unsuitable for testing in a laboratory environment. Related technologies have proposed a series of current-output wheel speed sensor signal simulation circuits based on the characteristics of wheel speed sensor signals and the working principle of their analytical circuits. These circuits overcome the shortcomings of building a real-world environment while still meeting basic testing requirements.

[0109] However, the above-mentioned existing technologies all have at least one of the following three problems: 1. The circuit does not have the function of injecting common electrical faults (short circuit to power supply, short circuit to ground, open circuit); 2. It does not take into account the generation of fault current of high-end current wheel speed sensors with functional safety mechanisms (such as the typical value of 3.5mA for TLE5046), and can only generate all or part of the output current of conventional wheel speed sensors of 7mA, 14mA, and 28mA; 3. Most current signal generation circuits are relatively complex.

[0110] To overcome the shortcomings of the prior art, the present invention provides a current output type wheel speed sensor signal simulation and fault injection circuit, comprising: a signal generation circuit and a fault injection circuit.

[0111] By analyzing the output characteristics of existing current-type wheel speed sensors, the current includes four typical values: 3.5mA (taking TLE5046 as an example), 7mA, 14mA, and 28mA. The sampling resistor in the sensor signal analysis circuit performs current-to-voltage conversion before analysis. Therefore, as long as a voltage waveform identical to the wheel speed sensor signal is generated across the sampling resistor in the analysis circuit, the simulation of the real wheel speed sensor signal can be achieved. The signal generation circuit is based on the voltage divider principle of two series resistors: with a fixed supply voltage and sampling resistor value, a change in the resistance value of the resistor connected in series with the sampling resistor will cause a change in the voltage across the sampling resistor. The series resistor with the sampling resistor is composed of at least four resistors connected in parallel as needed. The parallel state of the four resistors is controlled by the on / off state of an electronic switch, thus achieving the change in resistance value after parallel connection.

[0112] The fault injection circuit consists of three switch matrices. The open-circuit fault injection switch connects the sampling circuit pins and the signal generation circuit signal, and is used to disconnect the signal path; the short-circuit to power supply fault injection switch connects the sampling circuit pins and the power supply, and when the switch is closed, the power supply and the sampling circuit are connected; the short-circuit to ground fault injection switch connects the sampling circuit pins and ground, and when the switch is closed, the ground and the sampling circuit are connected.

[0113] The beneficial effects of this invention are: 1. It can completely simulate the current signals of existing active current output wheel speed sensors, namely 3.5mA (taking TLE5046 as an example), 7mA, 14mA and 28mA; 2. The circuit has the function of injecting common electrical faults (short circuit to power supply, short circuit to ground, open circuit); 3. The principle and circuit structure are simple, easy to implement and debug.

[0114] like Figure 7 As shown, the wheel speed sensor simulation device 700 includes a signal generation circuit 101 and a fault injection circuit 102. The signal generation circuit 101 includes an electronic switch 701 and resistors 702. The electronic switch 701 includes transistors Q1 to Q4, and the resistors 702 include resistors R5 to R8. Current signals of 3.5mA, 7mA, 14mA, and 28mA are achieved by controlling different combinations of R5 (corresponding to the third resistor unit), R6 (corresponding to the second resistor unit), R7 (corresponding to the first resistor unit), R8 (corresponding to the fourth resistor unit), and the sampling resistor RS. To accurately achieve the resistance values, each resistor R5, R6, R7, and R8 can be a combination of one or more resistors.

[0115] One end of resistor R5 is connected to the collector of PNP transistor Q1, and the other end is connected to the normally open contact of relay K1; one end of resistor R6 is connected to the collector of PNP transistor Q2, and the other end is connected to the normally open contact of relay K1; one end of resistor R7 is connected to PNP transistor Q3, and the other end is connected to the normally open contact of relay K1; one end of resistor R8 is connected to the collector of PNP transistor Q4, and the other end is connected to the normally open contact of relay K1. The electronic switch consists of PNP transistors Q1 (corresponding to the third switching unit), Q2 (corresponding to the second switching unit), Q3 (corresponding to the first switching unit), and Q4 (corresponding to the fourth switching unit) and resistors R1, R2, R3, and R4.

[0116] Q1's emitter is connected to power supply VCC, its collector is connected to resistor R5, and its base is connected to the control module's control port (e.g., MCU GPIO, ILCtrl) via resistor R1. Q2's emitter is connected to power supply VCC, its collector is connected to resistor R6, and its base is connected to the control module's control port (e.g., MCU GPIO, IMCtrl) via resistor R2. Q3's emitter is connected to power supply VCC, its collector is connected to resistor R7, and its base is connected to the control module's control port (e.g., MCU GPIO, IHCtrl) via resistor R3. Q4's emitter is connected to power supply VCC, its collector is connected to resistor R8, and its base is connected to the control module's control port (e.g., MCU GPIO, IErrorCtrl) via resistor R4.

[0117] To simplify calculations, assuming the on-state voltage drops of transistors Q1, Q2, Q3, and Q4 are not considered, the sampling resistor RS = 50Ω, VCC = 5V, R5 = 664Ω, R6 = 307Ω, R7 = 128Ω, and R8 = 1378Ω in the sensor signal analysis circuit shown in the diagram. In practical applications, the ideal effect can be achieved by adjusting the resistor values. The correspondence between the switching states of Q1, Q2, Q3, and Q4 and the circuit current and sampling resistor RS voltage is shown in Table 1 above. See the appendix for the corresponding waveforms. Figure 8 Wheel speed signals can be simulated by controlling the on / off state of Q1, Q2, Q3, and Q4.

[0118] like Figure 7 As shown, the fault injection circuit 102 includes three single-pole double-throw relays K1 (corresponding to the fifth switching unit), K2 (corresponding to the sixth switching unit), and K3 (corresponding to the seventh switching unit). By combining the opening and closing of different relays, faults such as open circuits in the wheel speed signal, short circuits to the power supply, and short circuits to ground can be injected.

[0119] The normally closed contact of K1 is connected to the common terminal of R5, R6, R7, and R8. The common point of K1 is also connected to the common point of K2 and the WSS pin of the external controller sampling circuit. The common point of K2 is also connected to the common point of K1 and the WSS pin of the external controller sampling circuit, and its normally open contact is connected to the power supply. The common point of K3 is also connected to the common point of K1 and the WSS pin of the external controller sampling circuit, and its normally open contact is connected to ground.

[0120] Based on this circuit design, the wheel speed sensor simulation device can inject faults into the wheel speed sampling interface of the external controller without disconnecting the external wheel speed sensor simulation device, and without damaging the speed sensor simulation device. The correspondence between the switch states of K1, K2, and K3 and the fault injection is shown in Table 2 above.

[0121] like Figure 7As shown, one end of K2 is connected to the VBAT terminal of power supply 703 (i.e., the second power supply in the above embodiment), and one end of K3 is connected to the GND terminal of power supply 703. The VBAT terminal and GND terminal of power supply 703 are respectively connected to wheel speed signal acquisition controller 800. Wheel speed signal acquisition controller 800 includes sampling resistor RS and signal processing circuit 801. Signal processing circuit 801 is used to process the voltage signal of sampling resistor RS.

[0122] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above steps / processes do not imply a sequential order of execution; the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above embodiments of this application are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0123] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0124] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0125] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0126] In addition, each functional unit in the various embodiments of this application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0127] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0128] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence or the part that contributes to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, magnetic disks, or optical disks.

[0129] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A wheel speed sensor analog circuit, characterized in that, The wheel speed sensor analog circuit includes a signal generation circuit and a fault injection circuit; the signal generation circuit includes a switching module and a resistor module. The switch module is connected to the resistor module, the resistor module is connected to the input terminal of the fault injection circuit, and the output terminal of the fault injection circuit is used to connect to the sampling resistor in the sampling circuit; wherein, The switching module is used to adjust the resistance value of the resistor module to change the voltage of the sampling resistor; The fault injection circuit is used to inject an electrical fault signal into the sampling circuit to simulate an electrical fault in the wheel speed sensor.

2. The circuit according to claim 1, characterized in that, The switching module includes multiple switching units, and the resistor module includes multiple resistor units; the number of switching units corresponds to the number of resistor units. The switching unit is connected in series with the corresponding resistor unit to form a signal generation branch; multiple signal generation branches are connected in parallel and then connected to the input terminal of the fault injection circuit.

3. The circuit according to claim 2, characterized in that, The switching unit is a transistor; the wheel speed sensor analog circuit also includes a control module; wherein... For each of the signal generation branches, the collector of the transistor in the signal generation branch is connected to the corresponding resistor unit, the emitter of the transistor in the signal generation branch is connected to the first power supply, and the base of the transistor in the signal generation branch is connected to the control port of the control module.

4. The circuit according to claim 3, characterized in that, The plurality of resistor units include a first resistor unit, a second resistor unit, a third resistor unit, and a fourth resistor unit with sequentially increasing resistance; the plurality of switch units include a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit; wherein, The collector of the first switching unit is connected to the first resistor unit, the emitter of the first switching unit is connected to the first power supply, and the base of the first switching unit is connected to the first control port of the control module. The collector of the second switching unit is connected to the second resistor unit, the emitter of the second switching unit is connected to the first power supply, and the base of the second switching unit is connected to the second control port of the control module. The collector of the third switching unit is connected to the third resistor unit, the emitter of the third switching unit is connected to the first power supply, and the base of the third switching unit is connected to the third control port of the control module. The collector of the fourth switching unit is connected to the fourth resistor unit, the emitter of the fourth switching unit is connected to the first power supply, and the base of the fourth switching unit is connected to the fourth control port of the control module.

5. The circuit according to claim 4, characterized in that, When the first switching unit, the second switching unit, the third switching unit, and the fourth switching unit are all disconnected, the voltage of the sampling resistor is 0. When the first switch unit, the second switch unit, and the third switch unit are all open, and the fourth switch unit is all closed, the voltage of the sampling resistor is the first voltage. When the first switch unit, the second switch unit, and the fourth switch unit are all open, and the third switch unit is all closed, the voltage of the sampling resistor is the second voltage. When the first switch unit, the fourth switch unit, and the third switch unit are all open, and the second switch unit is all closed, the voltage of the sampling resistor is the third voltage. When the fourth switch unit, the second switch unit, and the third switch unit are all open, and the first switch unit is all closed, the voltage of the sampling resistor is the fourth voltage. Among them, the first voltage, the second voltage, the third voltage, and the fourth voltage increase sequentially.

6. The circuit according to any one of claims 1 to 5, characterized in that, The fault injection circuit includes a fifth switching unit; the first end of the fifth switching unit is connected to the resistor module, and the second end of the fifth switching unit is used to connect to the sampling resistor.

7. The circuit according to claim 6, characterized in that, The fault injection circuit further includes a sixth switching unit; the first end of the sixth switching unit is connected to the second end of the fifth switching unit, the first end of the sixth switching unit is also used to connect to the sampling resistor, and the second end of the sixth switching unit is connected to the second power supply.

8. The circuit according to claim 7, characterized in that, The fault injection circuit further includes a seventh switching unit; the first end of the seventh switching unit is connected to the second end of the fifth switching unit, and the second end of the seventh switching unit is connected to the grounding terminal of the second power supply.

9. The circuit according to claim 8, characterized in that, When the fifth, sixth, and seventh switch units are all disconnected, the fault injection circuit injects an open-circuit fault signal into the sampling circuit. When the fifth switch unit is open, the seventh switch unit is open, and the sixth switch unit is on, the fault injection circuit injects a first short-circuit signal into the sampling circuit; The first short-circuit signal is used to characterize the sampling circuit as being in a short-circuit to power supply fault. When the fifth switch unit is open, the sixth switch unit is open, and the seventh switch unit is on, the fault injection circuit injects a first short-circuit signal into the sampling circuit; The first short-circuit signal is used to characterize that the sampling circuit is in a short-circuit to ground fault.

10. An analog sampling circuit, characterized in that, The analog acquisition circuit includes a wheel speed sensor analog circuit and a sampling circuit; the wheel speed sensor analog circuit includes a signal generation circuit and a fault injection circuit; the signal generation circuit includes a switching module and a resistor module; The switch module is connected to the resistor module, the resistor module is connected to the input terminal of the fault injection circuit, and the output terminal of the fault injection circuit is connected to the sampling circuit; wherein, The switching module is used to adjust the resistance value of the resistor module to change the voltage of the sampling resistor in the sampling circuit. The fault injection circuit is used to inject an electrical fault signal into the sampling circuit to simulate an electrical fault in the wheel speed sensor.

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