Wheel speed determination method and system and vehicle

Abstract

The invention discloses a wheel speed determination method. The method comprises the steps that a current signal generated by a wheel speed sensor of a vehicle based on wheel rotation is converted into a voltage pulse signal; collecting timestamp information and edge state information of the voltage pulse signal; based on the timestamp information and the edge state information, determining the edge number and timestamp change information of the voltage pulse signal in a preset calculation time period; and calculating the wheel speed of the vehicle based on the edge number and the timestamp change information. The invention further discloses a system and a vehicle applying the method.

Description

Technical Field

[0001] The present invention relates to the field of automotive electronic technology, and in particular to a wheel speed determination method, system and vehicle. Background Art

[0002] Wheel speed sensor is a sensor used to measure the rotation speed of the car wheels. For modern cars, wheel speed information is essential. Vehicle dynamic control system (VDC), electronic stability program (ESP), anti-lock braking system (ABS), automatic transmission control system, etc. all need wheel speed information. Therefore, wheel speed sensor is one of the most critical sensors in modern cars.

[0003] The commonly used wheel speed sensor is designed based on the principle of electromagnetic induction. It consists of a magnetic induction sensor head and a gear ring. The magnetic induction sensor head consists of a permanent magnet, a pole shaft, an induction coil, etc. The magnetic induction sensor head is a stationary component. There is a certain gap between the magnetic pole of the magnetic induction sensor head and the end face of the gear ring. The gear ring is a moving component, which is generally installed on the wheel hub or axle of the car and rotates with the wheel. When the wheel rotates, the gear ring rotates synchronously with the wheel. The teeth and gaps on the gear ring pass through the magnetic field of the wheel speed sensor in turn and quickly, generating a current signal by cutting the magnetic flux lines.

[0004] An application specific integrated circuit (ASIC) chip is a chip that implements user-specific functions by integrating circuits inside the chip. Existing technology usually uses the more expensive ASIC chip to convert the current signal generated by the wheel speed sensor into a voltage pulse signal, and transmits the voltage pulse signal to the car's MCU through software interrupt technology. The MCU is composed of a CPU, memory, peripherals, etc., and realizes the function of controlling the entire car system. The MCU determines the wheel speed of the car by analyzing the voltage pulse signal.

[0005] Since ASCI chips are expensive, the cost of determining the vehicle wheel speed technology is high; the voltage pulse signal is transmitted through software interrupt technology, resulting in a high CPU load on the MCU, which in turn leads to a longer response time for user requests and a poorer user experience. Summary of the invention

[0006] In order to solve the above technical problems, the present invention specifically provides the following technical solutions.

[0007] The present invention provides a wheel speed determination method, comprising the following steps: S1, converting the current signal generated by the wheel speed sensor of the vehicle based on the rotation of the wheel into a voltage pulse signal; S2, collecting timestamp information and edge status information of the voltage pulse signal; S3, determining the edge number and timestamp change information of the voltage pulse signal within a preset calculation period based on the timestamp information and edge state information; S4, calculating the wheel speed of the vehicle based on the edge count and timestamp change information.

[0008] Optionally, the step S1 includes: converting a current signal generated by a wheel speed sensor of the vehicle based on wheel rotation into a voltage pulse signal through a current comparator.

[0009] Optionally, step S1 includes the following sub-steps: S11, inputting the current signal of the preset first current interval into a primary current comparator, and inputting the current signal of the preset second current interval into a secondary current comparator; S12, converting the current signal higher than the preset first current threshold into a high-level voltage pulse signal through the primary current comparator, and converting the current signal lower than the first current threshold into a low-level voltage pulse signal; S13, converting the current signal higher than the preset second current threshold into a high-level voltage pulse signal through the secondary current comparator, and converting the current signal lower than the second current threshold into a low-level voltage pulse signal.

[0010] Optionally, step S2 includes the following sub-steps: S21, collecting the timestamp information and edge status information of each edge of the voltage pulse signal through a microcontroller (MCU) of the vehicle according to a preset task cycle; S22, transmitting the timestamp information and the edge status information to a cache of the MCU through a direct memory access (DMA) channel of the MCU.

[0011] Optionally, the sub-step S22 includes the following operations: S221, transmitting the timestamp information and edge status information of each task cycle to the cache of the MCU through the DMA channel; S222, receiving the timestamp information and edge status information of the current task cycle through a cache in the MCU, and receiving the timestamp information and edge status information of the previous task cycle through another cache in the MCU.

[0012] Optionally, the sub-step S22 further includes the following operations: S223 , before the cache of the MCU receives the timestamp information and edge status information of the current task cycle, store the timestamp information and edge status information in the cache of the MCU into a random access memory (RAM) of the MCU.

[0013] Optionally, step S3 includes the following sub-steps: S31, counting the number of timestamp information or edge status information received by the cache of the MCU in the current task cycle; S32, determining the quantity of the timestamp information or the edge status information as the number of edges of the voltage pulse signal in the current task cycle.

[0014] Optionally, step S3 further includes the following sub-steps: S33, determining whether each edge status information of the current task cycle and the historical task cycle is a rising edge or a falling edge; S34, determining the difference between the timestamp information of the latest rising edge of the current task cycle and the last rising edge of the historical task cycle as the first time difference; S35, determining the difference between the timestamp information of the latest falling edge of the current task cycle and the previous falling edge of the historical task cycle as the second time difference; S36, determining a calculation result of adding the first time difference and the second time difference as timestamp change information of the voltage pulse signal in the current task cycle.

[0015] In addition, the present invention also provides a wheel speed determination system, comprising: A signal conversion module, used to convert a current signal generated by a wheel speed sensor of the vehicle based on wheel rotation into a voltage pulse signal; A timestamp acquisition module, used for acquiring timestamp information and edge status information of the voltage pulse signal; An edge number and timestamp change information determination module, used to determine the edge number and timestamp change information of the voltage pulse signal within a preset calculation period based on the timestamp information and edge state information; The wheel speed calculation module is used to calculate the wheel speed of the vehicle based on the edge number and timestamp change information.

[0016] In addition, the present invention also provides a vehicle, comprising the wheel speed determination system as described above.

[0017] Through the above technical solution, the function of converting the current signal of the wheel speed sensor into a voltage pulse signal without relying on an ASIC chip can be realized, and the function of transmitting the voltage pulse signal without relying on the software interrupt technology can also be realized. The problem of high cost of determining the wheel speed of the car is solved, and the problem of high CPU load of the MCU caused by transmitting the voltage pulse signal through the software interrupt technology is also solved, thereby achieving the purpose of providing a low-cost and low-load wheel speed determination technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a flow chart of a wheel speed determination method provided by an embodiment of the present invention; Figure 2 A schematic diagram of voltage conversion of a wheel speed determination method provided by an embodiment of the present invention; Figure 3 A schematic diagram of a voltage pulse signal in each task cycle of a wheel speed determination method provided by an embodiment of the present invention; Figure 4 A schematic diagram of modules of a wheel speed determination system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] The specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Although the various steps in the flowchart in the embodiment of the present invention are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless clearly stated herein, the execution of these steps is not strictly limited in order, and they can be executed in other orders. Moreover, at least a portion of the steps in the figure may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0022] Although the terms first, second, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information.

[0023] See also Figure 1 According to one aspect of the present application, there is provided a method for determining a wheel speed, comprising the following steps: S1, converting the current signal generated by the vehicle's wheel speed sensor based on wheel rotation into a voltage pulse signal.

[0024] There are three types of wheel speed sensors currently on the market: standard (stand) protocol type, pulse width modulation (PWM) protocol type, and intelligent (AK) protocol type. Depending on different customer projects, the type of wheel speed sensor used will change. The present invention can be applied to different types of wheel speed sensors, which is convenient and fast.

[0025] S2, collecting timestamp information and edge status information of the voltage pulse signal.

[0026] The voltage pulse signal is a PWM waveform, and each edge of the voltage pulse signal includes a timestamp information and an edge state information.

[0027] S3, based on the timestamp information and edge status information, determining the edge number and timestamp change information of the voltage pulse signal within a preset calculation period.

[0028] S4, calculating the wheel speed of the vehicle based on the edge count and timestamp change information.

[0029] The step S1 may include: converting a current signal generated by a wheel speed sensor of the vehicle based on wheel rotation into a voltage pulse signal through a current comparator.

[0030] See also Figure 2 , the step S1 may include the following sub-steps: S11, inputting the current signal of the preset first current interval into a primary current comparator, and inputting the current signal of the preset second current interval into a secondary current comparator.

[0031] In this embodiment, the preset first current interval is preferably 14 mA to 28 mA, and the preset second current interval is preferably 7 mA to 14 mA.

[0032] The wheel speed sensor of the stand protocol type includes two current gears of 7 mA and 14 mA, and the current signal outputted by the sensor jumps back and forth between 7 mA and 14 mA. Therefore, the current signal outputted by the wheel speed sensor of the stand protocol type will be inputted into the secondary current comparator.

[0033] The wheel speed sensor of the PWM protocol type includes two current gears of 7 mA and 14 mA, and the current signal outputted by the wheel speed sensor of the PWM protocol type jumps back and forth between 7 mA and 14 mA. Therefore, the current signal outputted by the wheel speed sensor of the PWM protocol type will be inputted into the secondary current comparator.

[0034] The wheel speed sensor of the AK protocol type includes three current gears, namely 7 mA, 14 mA and 28 mA, and the current signal outputted by the wheel speed sensor of the AK protocol type jumps back and forth between 7 mA, 14 mA and 28 mA. Therefore, the current signal between 7 mA and 14 mA outputted by the wheel speed sensor of the AK protocol type will be input into the secondary current comparator, and the current signal between 14 mA and 28 mA outputted by the wheel speed sensor of the AK protocol type will be input into the primary current comparator.

[0035] S12, converting the current signal higher than the preset first current threshold into a high-level voltage pulse signal through the primary current comparator, and converting the current signal lower than the first current threshold into a low-level voltage pulse signal.

[0036] In this implementation, the preset first current threshold is preferably 20 mA.

[0037] S13, converting the current signal higher than the preset second current threshold into a high-level voltage pulse signal through the secondary current comparator, and converting the current signal lower than the second current threshold into a low-level voltage pulse signal.

[0038] In this embodiment, the preset second current threshold is preferably 10 mA.

[0039] Through the above technical solution, it is possible to realize the function of converting the current signals of different types of wheel speed sensors into voltage pulse signals through current comparators without relying on ASIC chips, thereby solving the problem of high cost of determining automobile wheel speed technology and achieving the purpose of providing low-cost wheel speed determination technology.

[0040] The present invention converts current signals of different types of wheel speed sensors into voltage pulse signals through a primary current comparator and a secondary current comparator, thereby achieving the purpose of being flexibly compatible with different types of wheel speed sensors on the market.

[0041] The step S2 may include the following sub-steps: S21, according to a preset task cycle, collecting the timestamp information and edge status information of each edge of the voltage pulse signal through the MCU.

[0042] In this implementation manner, the preset calculation period may include more than one task cycle, and each task cycle is preferably 5 milliseconds.

[0043] In this embodiment, the timestamp information and edge status information of each edge can be received through the register of the MCU. The register can only receive the timestamp information and edge status information of one edge at a time, and the timestamp information and edge status information received last are overwritten by the latest received timestamp information and edge status information. The register can be a register in the input capture unit (ICU) of the MCU, and the function of the ICU is to help the MCU implement the input capture function.

[0044] A counter is provided inside the ICU. In the present embodiment, the counter is preferably a 16-bit counter, which counts cyclically from 0 to 65535. When each edge of the voltage pulse signal enters the ICU, the counter counts once, and each edge records the count value of the counter as the timestamp information of the edge.

[0045] S22, transmitting the timestamp information and edge status information to the cache of the MCU through the DMA channel of the MCU.

[0046] The DMA channel is a peripheral module inside the MCU that directly accesses the memory. The DMA channel can quickly move data from the source address to the destination address without CPU intervention. In this embodiment, the source address is the register of the MCU, and the destination address is the cache of the MCU.

[0047] In this implementation, the cache of the MCU may be included in a random access memory (RAM) of the MCU.

[0048] The sub-step S22 may include the following operations: S221, transmitting the timestamp information and edge status information of each task cycle to the cache of the MCU through the DMA channel.

[0049] S222, receiving the timestamp information and edge status information of the current task cycle through one cache in the MCU, and receiving the timestamp information and edge status information of the previous task cycle through another cache in the MCU. The two caches in the MCU are used alternately.

[0050] In this implementation, within each task cycle, the single cache of the MCU can receive timestamp information and edge status information of no more than 64 edges. Therefore, the two caches in the MCU are preferably capable of storing timestamp information and edge status information of up to 64 edges.

[0051] The sub-step S22 may also include the following operations: S223, before the cache of the MCU receives the timestamp information and edge status information of the current task cycle, store the timestamp information and edge status information in the cache of the MCU into the RAM of the MCU.

[0052] The principle of this operation is that before the timestamp information and edge status information in the cache of the MCU are overwritten, they are stored in the RAM of the MCU, which can ensure that in subsequent steps, the wheel speed of the vehicle can be determined based on the various edge status information and timestamp information of the current task cycle and the historical task cycle.

[0053] Through the above technical solution, without the intervention of the MCU CPU, the timestamp information and edge status information are quickly moved from the MCU register to the MCU cache through the DMA channel, which can greatly reduce the consumption of the MCU CPU resources, thereby reducing the MCU CPU load rate, and thus achieving the purpose of providing a low-load wheel speed determination technology.

[0054] The step S3 may include the following sub-steps: S31, counting the amount of the timestamp information or edge status information received by the cache of the MCU in the current task cycle.

[0055] S32, determining the quantity of the timestamp information or the edge status information as the number of edges of the voltage pulse signal in the current task cycle.

[0056] The step S3 may further include the following sub-steps: S33, determining whether each edge status information of the current task cycle and the historical task cycle is a rising edge or a falling edge.

[0057] The edge status information of each edge records whether the edge is a high level or a low level. According to the edge status information, it can be determined whether the edge is a rising edge or a falling edge: when the edge status information of the edge is a high level, the edge is a rising edge; when the edge status information of the edge is a low level, the edge is a falling edge.

[0058] S34, determining the difference between the timestamp information of the latest rising edge of the current task cycle and the last rising edge of the historical task cycle as the first time difference.

[0059] S35, determining the difference between the timestamp information of the latest falling edge of the current task cycle and the last falling edge of the historical task cycle as the second time difference.

[0060] S36, determining a calculation result of adding the first time difference and the second time difference as timestamp change information of the voltage pulse signal in the current task cycle. See also Figure 3 , x0-7 is the timestamp information of the voltage pulse signal.

[0061] In the second task cycle, the edge number is 1, the timestamp information of the latest rising edge of the current task cycle is x2, and the timestamp information of the previous rising edge of the historical task cycle is x0, so the first time difference is the difference between x2 and x0. There is no falling edge in the current task cycle, so the second time difference is 0, and the timestamp change information of the voltage pulse signal in the current task cycle is the difference between x2 and x0.

[0062] In the third task cycle, the number of edges is 2, the timestamp information of the latest rising edge of the current task cycle is x4, and the timestamp information of the previous rising edge of the historical task cycle is x2, so the first time difference is the difference between x4 and x2. The timestamp information of the latest falling edge of the current task cycle is x3, and the timestamp information of the previous falling edge of the historical task cycle is x1, so the second time difference is the difference between x3 and x1, and the timestamp change information of the voltage pulse signal of the current task cycle is the calculation result of adding the first time difference and the second time difference.

[0063] In the fourth task cycle, the number of edges is 3, the timestamp information of the latest rising edge of the current task cycle is x7, and the timestamp information of the previous rising edge of the historical task cycle is x3, so the first time difference is the difference between x7 and x3. The timestamp information of the latest falling edge of the current task cycle is x6, and the timestamp information of the previous falling edge of the historical task cycle is x4, so the second time difference is the difference between x6 and x4, and the timestamp change information of the voltage pulse signal of the current task cycle is the calculation result of adding the first time difference and the second time difference.

[0064] See also Figure 4 According to another aspect of the present application, there is provided a wheel speed determination system, comprising: The signal conversion module 1 is used to convert the current signal generated by the wheel speed sensor of the vehicle based on the rotation of the wheel into a voltage pulse signal.

[0065] The timestamp acquisition module 2 is used to acquire the timestamp information and edge status information of the voltage pulse signal.

[0066] The edge number and timestamp change information determination module 3 is used to determine the edge number and timestamp change information of the voltage pulse signal within a preset calculation period based on the timestamp information and edge state information.

[0067] The wheel speed calculation module 4 is used to calculate the wheel speed of the vehicle based on the edge number and timestamp change information.

[0068] An embodiment of another aspect of the present application provides a vehicle, comprising the wheel speed determination system as described above.

[0069] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] In this document, the terms "comprises," "comprising" or any other variations thereof are intended to cover a non-exclusive inclusion of elements other than those listed and may also include other elements not expressly listed.

[0071] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for determining wheel speed, characterized in that: The following steps are involved: S1, converting the current signal generated by the wheel speed sensor of the vehicle based on the rotation of the wheel into a voltage pulse signal; S2, collecting timestamp information and edge status information of the voltage pulse signal; S3, determining the edge number and timestamp change information of the voltage pulse signal within a preset calculation period based on the timestamp information and the edge state information; S4, calculating the wheel speed of the vehicle based on the edge count and timestamp change information.

2. The wheel speed determination method according to claim 1, characterized in that: The step S1 includes: converting a current signal generated by a wheel speed sensor of the vehicle based on wheel rotation into a voltage pulse signal through a current comparator.

3. The wheel speed determination method according to claim 2, characterized in that: The step S1 comprises the following sub-steps: S11, inputting the current signal of the preset first current interval into a primary current comparator, and inputting the current signal of the preset second current interval into a secondary current comparator; S12, converting the current signal higher than the preset first current threshold into a high-level voltage pulse signal through the primary current comparator, and converting the current signal lower than the first current threshold into a low-level voltage pulse signal; S13, converting the current signal higher than the preset second current threshold into a high-level voltage pulse signal through the secondary current comparator, and converting the current signal lower than the second current threshold into a low-level voltage pulse signal.

4. The wheel speed determination method according to claim 1, characterized in that: The step S2 comprises the following sub-steps: S21, collecting the timestamp information and edge status information of each edge of the voltage pulse signal through a microcontroller (MCU) of the vehicle according to a preset task cycle; S22, transmitting the timestamp information and the edge status information to a cache of the MCU through a direct memory access (DMA) channel of the MCU.

5. The wheel speed determination method according to claim 4, characterized in that: The sub-step S22 includes the following operations: S221, transmitting the timestamp information and edge status information of each task cycle to the cache of the MCU through the DMA channel; S222, receiving the timestamp information and edge status information of the current task cycle through a cache in the MCU, and receiving the timestamp information and edge status information of the previous task cycle through another cache in the MCU.

6. The wheel speed determination method according to claim 5, characterized in that: The sub-step S22 further includes the following operations: S223 , before the cache of the MCU receives the timestamp information and edge status information of the current task cycle, store the timestamp information and edge status information in the cache of the MCU into a random access memory (RAM) of the MCU.

7. The wheel speed determination method according to claim 6, characterized in that: The step S3 comprises the following sub-steps: S31, counting the number of timestamp information or edge status information received by the cache of the MCU in the current task cycle; S32, determining the quantity of the timestamp information or the edge status information as the number of edges of the voltage pulse signal in the current task cycle.

8. The wheel speed determination method according to claim 7, characterized in that: The step S3 also includes the following sub-steps: S33, determining whether each edge status information of the current task cycle and the historical task cycle is a rising edge or a falling edge; S34, determining the difference between the timestamp information of the latest rising edge of the current task cycle and the last rising edge of the historical task cycle as the first time difference; S35, determining the difference between the timestamp information of the latest falling edge of the current task cycle and the previous falling edge of the historical task cycle as the second time difference; S36, determining a calculation result of adding the first time difference and the second time difference as timestamp change information of the voltage pulse signal in the current task cycle.

9. A wheel speed determination system, characterized in that: include: A signal conversion module, used to convert a current signal generated by a wheel speed sensor of the vehicle based on wheel rotation into a voltage pulse signal; A timestamp acquisition module, used for acquiring timestamp information and edge status information of the voltage pulse signal; An edge number and timestamp change information determination module, used to determine the edge number and timestamp change information of the voltage pulse signal within a preset calculation period based on the timestamp information and edge state information; The wheel speed calculation module is used to calculate the wheel speed of the vehicle based on the edge number and timestamp change information.

10. A vehicle, characterized in that: Comprising the wheel speed determination system as claimed in claim 9.

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