Wheel speed estimation method and system under wheel speed sensor fault

Abstract

The invention discloses a wheel speed estimation method and system under a wheel speed sensor fault, and the method comprises the steps: judging the fault type of a fault sensor when a wheel speed sensor fault occurs; if only the abnormal fault exists, calculating a corrected wheel speed according to other wheel speeds except the maximum wheel speed and the minimum wheel speed in the wheel speeds in the current fault detection period, and calculating an estimated wheel speed of the abnormal sensor in combination with the corrected wheel speed and a previous fault detection period wheel speed corresponding to the abnormal sensor; if the failure type fault exists and the number of the failure type sensors is smaller than the number of the whole vehicle sensors, the average value of the wheel speeds measured by the non-failure type sensors serves as the estimated wheel speed of all the failure type sensors; if the number of the failure type sensors is equal to the number of the whole vehicle sensors, the estimated wheel speed of the failure type sensors is calculated by combining the wheel speed of the last fault detection period corresponding to the failure type sensors and the whole vehicle speed variable quantity of the last fault detection period. The wheel speed loss caused by sensor faults is effectively avoided, and the wheel speed accuracy is improved.

Description

Technical Field

[0001] The present application relates to the field of automobile technology, and in particular to a method and system for estimating wheel speed when a wheel speed sensor fails. Background Art

[0002] As a type of wire control brake system, the Electronic Stability Controller (ESC) is an electronic control device developed to improve the driver's operating convenience and driving safety. Wheel speed is an important vehicle state parameter that needs to be identified in the ESC software dynamics control architecture. ESC calculates parameters such as vehicle speed, target slip rate, target braking torque, target driving torque, etc. by receiving wheel speed signals to improve the lateral and longitudinal stability of the vehicle.

[0003] Generally speaking, a low slip rate means that the vehicle has good grip and stable driving, while a high slip rate means that the wheels are slipping to a greater extent, and the vehicle may lose stability, increasing the risk of skidding or drifting. If the wheel speed of a wheel is abnormal (for example, the wheel is slipping), this will cause the slip rate of the wheel to increase, thereby affecting the traction and handling of the vehicle, especially on slippery or icy roads, where changes in wheel speed and slip rate have a more significant impact on vehicle control. The ESC system calculates the vehicle's slip rate by monitoring the wheel speed. If it detects that the slip rate of a wheel is too large, the system will intervene to brake or adjust the power output to reduce the slip rate and restore vehicle stability.

[0004] However, in reality, wheel speed sensors, as weak current systems, are subject to electromagnetic interference from other systems or other environmental factors. The failure rate of wheel speed sensors accounts for 30% of the ESC failure rate. Wheel speed sensor failure will cause the ESC system to be unable to correctly obtain wheel speed information, and thus cannot accurately determine the slip rate. When the correct wheel speed and slip rate data cannot be obtained, the system cannot intervene effectively, and unnecessary interventions (such as incorrect application of brakes) may occur, or even loss of control of vehicle stability, especially in sharp turns or slippery road conditions, increasing driving risks.

[0005] Therefore, a method is needed to estimate the wheel speed corresponding to the faulty wheel speed sensor, so as to solve the technical problem that the wheel speed sensor fails, resulting in missing wheel speed and inaccurate measured wheel speed. Summary of the invention

[0006] The present application provides a wheel speed estimation method and system under wheel speed sensor failure, which can solve the technical problem that wheel speed is missing and the measured wheel speed is inaccurate due to wheel speed sensor failure.

[0007] To achieve the above objectives, in a first aspect, the present application provides a method for estimating wheel speed when a wheel speed sensor fails, the method comprising:

[0008] When a wheel speed sensor fault occurs, determine the fault type of the faulty sensor.

[0009] If only an abnormal fault exists, the corrected wheel speed is calculated based on the remaining wheel speeds in the current fault detection cycle except the maximum wheel speed and the minimum wheel speed. The estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0010] If there is a failure type fault and the number of failure type sensors is less than the number of sensors in the whole vehicle, the average value of the wheel speeds measured by the non-failure type sensors shall be used as the estimated wheel speed of each failure type sensor; if the number of failure type sensors is equal to the number of sensors in the whole vehicle, the estimated wheel speed of the failure type sensor shall be calculated based on the wheel speed corresponding to the failure type sensor in the previous fault detection cycle and the change in the vehicle speed in the previous fault detection cycle.

[0011] Furthermore, in one embodiment, the failure type fault refers to:

[0012] The sensor is in an open circuit state or a short circuit state. The sensor in each state cannot output the wheel speed.

[0013] Each state is judged by the analog voltage of the sensor and the preset voltage threshold range of each state.

[0014] Furthermore, in one embodiment, the abnormal fault includes:

[0015] The wheel speed exceeds the normal vehicle speed range, the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, the vehicle speed is greater than the preset vehicle speed and the wheel speed is less than the preset wheel speed, the number of wheel pulses is not within the expected range, and the absolute value of the change rate of the wheel speed between the current fault detection cycle and the previous fault detection cycle is greater than the preset change rate absolute value threshold; the abnormal sensor has wheel speed output, but the output value is abnormal.

[0016] Furthermore, in one embodiment, the calculating of the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle includes:

[0017] The credibility of each wheel speed in the current fault detection cycle is determined according to the preset fuzzy rules.

[0018] The remaining wheel speeds of the vehicle except the maximum wheel speed and the minimum wheel speed are taken as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their credibility.

[0019] Furthermore, in one embodiment, the combining of the corrected wheel speed and the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor to calculate the estimated wheel speed of the abnormal sensor includes:

[0020] According to the credibility of each wheel speed of the vehicle, the corresponding weight coefficient is calculated.

[0021] Combining the corrected wheel speed, the wheel speed of the previous fault detection cycle and the weight coefficient, the linear difference method is used to calculate the estimated wheel speed of the corresponding abnormal sensor.

[0022] Furthermore, in one embodiment, if there is a failure type fault, there is only a failure type sensor, and the remaining non-failure type sensors are fault-free sensors. When the number of failure type sensors is less than the number of sensors in the entire vehicle, the average wheel speed of the fault-free sensors is used as the estimated wheel speed of each failure type sensor.

[0023] Furthermore, in one embodiment, if there is a failure type fault, there are both failed sensors and abnormal sensors, and when the number of failed sensors is less than the number of sensors in the entire vehicle, the average value of the wheel speeds corresponding to the sensors except the failed sensors is used as the estimated wheel speed of each failed sensor.

[0024] Furthermore, in one embodiment, the average value of the wheel speeds corresponding to the sensors other than the failed sensors is used as the estimated wheel speed of each failed sensor, including:

[0025] If all sensors except the failed sensor are abnormal sensors, the average value of the estimated wheel speeds of the abnormal sensors is used as the estimated wheel speed of each failed sensor.

[0026] If there are abnormal sensors and normal sensors in addition to the failed sensors, the average value of the estimated wheel speeds of the abnormal sensors and the normal sensors is taken as the estimated wheel speeds of the failed sensors.

[0027] Furthermore, in one embodiment, the step of calculating the estimated wheel speed of the failed sensor in combination with the wheel speed of the failed sensor in the previous fault detection cycle and the vehicle speed change in the previous fault detection cycle includes:

[0028] Get the vehicle acceleration during the last fault detection cycle.

[0029] The estimated wheel speed of the corresponding failed sensor is calculated by combining the wheel speed of the previous fault detection cycle, the vehicle acceleration of the previous fault detection cycle, and the fault detection cycle.

[0030] In a second aspect, based on the above-mentioned wheel speed estimation method under wheel speed sensor failure, the present application provides a wheel speed estimation system of the wheel speed estimation method under wheel speed sensor failure, the system comprising:

[0031] The judgment module is used to judge the fault type of the faulty sensor when a wheel speed sensor fault occurs.

[0032] An estimation module is used to calculate the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle when only an abnormal fault exists, and calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; it is also used to use the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor when there is a failure fault and the number of failure sensors is less than the number of sensors of the whole vehicle; it is also used to calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in the vehicle speed of the previous fault detection cycle when there is a failure fault and the number of failure sensors is equal to the number of sensors of the whole vehicle.

[0033] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0034] When a wheel speed sensor fails, the present application determines the fault type of the fault sensor, designs corresponding wheel speed estimation algorithms for different types of faults to calculate the wheel speed corresponding to the fault sensor; if only an abnormal fault exists, the corrected wheel speed is calculated according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle, and the estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; if a failure fault exists, and the number of failure sensors is less than the number of sensors of the whole vehicle, the average value of the wheel speed measured by the non-failure sensor is used as the estimated wheel speed of each failure sensor; if the number of failure sensors is equal to the number of sensors of the whole vehicle, the estimated wheel speed of the failure sensor is calculated by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in the vehicle speed of the previous fault detection cycle. The invention effectively avoids the missing wheel speed caused by the failure of the wheel speed sensor without output value, and improves the accuracy of wheel speed reading under the failure of the wheel speed sensor with abnormal output value, thereby effectively improving the correctness of slip rate calculation and enhancing the control of vehicle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for estimating wheel speed when a wheel speed sensor fails according to an embodiment of the present application.

[0036] Figure 2 Schematic diagram of the membership function of the fuzzy subset in the embodiment of the present application.

[0037] Figure 3 Schematic diagram of a wheel speed estimation method when a failure type fault exists in an embodiment of the present application.

[0038] Figure 4Block diagram of a wheel speed estimation system when a wheel speed sensor fails in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0041] In a first aspect, an embodiment of the present application provides a method for estimating wheel speed when a wheel speed sensor fails.

[0042] In one embodiment, see Figure 1 As shown, the above wheel speed estimation method includes:

[0043] S1. Wheel speed sensor failure occurs.

[0044] S2. Determine the fault type of the faulty sensor; if only an abnormal fault exists, proceed to S3; if a failure fault exists, proceed to S4.

[0045] S3. Calculate a corrected wheel speed based on the remaining wheel speeds in the current fault detection cycle except the maximum wheel speed and the minimum wheel speed, and calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0046] S4, determine the relationship between the number of failed sensors and the number of vehicle sensors. If the number of failed sensors is less than the number of vehicle sensors, proceed to S5; if the number of failed sensors is equal to the number of vehicle sensors, proceed to S6.

[0047] S5. Taking the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor.

[0048] S6. Calculate the estimated wheel speed of the failed sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failed sensor and the change in vehicle speed of the previous fault detection cycle.

[0049] When a wheel speed sensor fails, the present application determines the fault type of the faulty sensor to see whether there is only an abnormal fault or a failure fault, and designs corresponding wheel speed estimation algorithms for different types of faults to calculate the wheel speed corresponding to the faulty sensor. The present application effectively avoids the loss of wheel speed caused by a wheel speed sensor with no output value, and improves the accuracy of wheel speed reading when the wheel speed sensor has an abnormal output value fault, thereby effectively improving the correctness of slip rate calculation and enhancing control over vehicle stability. Moreover, the method only adds software control logic to determine the fault type of the wheel speed sensor and uses the designed estimation algorithm to calculate the wheel speed of the corresponding fault type, and does not require any hardware development.

[0050] Further, in one embodiment, in the above step S3, the corrected wheel speed is calculated according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle, and the estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor, including:

[0051] S31. Determine the credibility of each wheel speed in the current fault detection cycle according to a preset fuzzy rule.

[0052] S32: The remaining wheel speeds of the vehicle except the maximum wheel speed and the minimum wheel speed are taken as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their credibility. Specifically:

[0053] Sort the four wheel speeds of the vehicle by size and find the second and third wheel speeds, which are the normal wheel speeds.

[0054] The corrected wheel speed is calculated using the normal wheel speed and its reliability, based on the following calculation formula:

[0055] Among them, V w_cor represents the corrected wheel speed, i represents the number of normal wheel speeds, R wi Indicates the reliability of normal wheel speed, V wi represents the normal wheel speed of the ith wheel, V wi The calculation formula is: Among them, n is the cumulative number of pulses in the current fault detection cycle, Z is the number of teeth in the ring gear, R is the radius of the wheel, and t is the time length corresponding to a fault detection cycle.

[0056] S33. Calculate the corresponding weight coefficient according to the credibility of each wheel speed of the vehicle. The formula is: Where m represents the position of the wheel, m=1, 2, 3, 4 represent the front left wheel, front right wheel, rear left wheel and rear right wheel respectively, R wm Indicates the reliability of each wheel speed of the vehicle.

[0057] S34, combining the corrected wheel speed, the wheel speed of the previous fault detection cycle and the weight coefficient, using the linear difference method to calculate the estimated wheel speed of the corresponding abnormal sensor. The formula is: V wp =K p ·V wp_last +(1-K p )·V w_cor , where K p Indicates the weight coefficient corresponding to the abnormal sensor in the current fault detection cycle, V wp_last Indicates the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0058] In this embodiment, when only an abnormal fault exists in a fault detection cycle, that is, the sensor can output a wheel speed value, but the output wheel speed value is abnormal, the wheel speed corresponding to the abnormal sensor in the fault detection cycle is calculated by combining the calculated corrected wheel speed and the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor, and the estimation algorithm is used to calculate the wheel speed corresponding to the abnormal sensor in the fault detection cycle. This ensures that when the wheel speed sensor has a fault with an abnormal output wheel speed value, the wheel speed can still be obtained more accurately.

[0059] Furthermore, in one embodiment, the specific steps in the above step S31 include:

[0060] S311. Define fuzzy rule input variables, the input variables include |V w -V w_last |、|V wmax -V wmin |、N ABS 、N VDC and N TCS , the meaning of each input variable is:

[0061] Describes the absolute value of the change in the speed of a single wheel per unit time, that is, the acceleration (or deceleration) of the vehicle, which is directly related to the acceleration or deceleration process of the vehicle.

[0062] Describes the absolute value of the acceleration gradient of a single wheel, that is, the amplitude of change during acceleration or deceleration.

[0063] |V w -V w_last |: Describes the absolute value of the rate of change of a single wheel speed between the current cycle and the previous cycle. If the wheel speed fluctuation rate is large, it means that there may be some irregular changes in the vehicle during driving.

[0064] |V wmax -V wmin|: Describes the absolute value of the wheel speed fluctuation rate of a single wheel, which refers to the fluctuation amplitude of the wheel speed within a certain period of time. If the wheel speed fluctuation rate is large, it means that there may be some rapid fluctuations during the driving process of the vehicle.

[0065] N ABS : Describes the number of wheels under ABS control during vehicle instability.

[0066] N VDC : Describes the number of wheels under VDC control during vehicle instability.

[0067] N TCS : Describes the number of wheels under TCS control during vehicle instability.

[0068] S312. Formulate fuzzy rules:

[0069] Rule 1: wheel speed fault counter OutRange_cnt, noise fault counter Noise_cnt, wheel speed loss fault counter WhlSpdMiss_cnt, pulse fault counter Pluse_cnt, tooth missing fault counter Teeth_cnt, open circuit fault counter Open_cnt, short circuit fault counter Short_cnt. The smaller the values ​​of the above fault counters, the higher the wheel speed stability and the greater the corresponding credibility.

[0070] Rule 2: Steady driving The smaller the value of |V wmax -V wmin The smaller the value of |, the higher the wheel stability, and the corresponding reliability R wi The bigger.

[0071] Rule 3: The smaller it is, the higher the wheel speed stability is, and the corresponding reliability R wi The larger the value, the greater the wheel acceleration changes dramatically in a short period of time, which means that the operation during driving is very intense, and the corresponding reliability R wi The lower it is.

[0072] Rule 4: When the vehicle is under normal braking conditions, the smaller the number of wheels under ABS / VDC / TCS control, the higher the wheel speed stability and the greater the corresponding credibility.

[0073] S313, establish the following for the input fuzzy variables: Figure 2 The fuzzy subsets shown in the figure have fuzzy languages ​​of S (Small), M (Medium), and L (Large). The parameters of each input fuzzy variable vary according to the domain. The parameters of each input fuzzy variable are shown in the following table. The parameter selection of the fuzzy subset needs to be based on a large amount of experimental data.

[0074]

[0075] S314, respectively calculating the membership degree of the above rule 1, rule 2, rule 3, rule 3, and rule 4 for each wheel speed, and taking the maximum value among the membership degrees as the credibility of the corresponding wheel speed.

[0076] Specifically, taking Rule 2 as an example, if Take μ S (10) = 0.2, μ M (10) = 0.6, then μ S With μ M The minimum value in is 0.2. If |V wmax -V wmin |=3,μ S (10) = 0.4, then take With V wmax -V wmin |The smaller value 0.2 is used as the membership degree μ of rule 2 ruler2 . Calculate the membership degree μ of rule 1, rule 2, rule 3, and rule 4 for each wheel speed ruler1 , μ ruler2 , μ ruler3 , μ ruler4 , take the maximum value of the membership degree of each rule as the credibility of the corresponding wheel speed, that is, R wm =max{μ ruler1 ,μ ruler2 ,μ ruler3 ,μ ruler4}.

[0077] Further, in one embodiment, the abnormal fault in the above step S2 includes:

[0078] The wheel speed exceeds the normal vehicle speed range, the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, the vehicle speed is greater than the preset vehicle speed and the wheel speed is less than the preset wheel speed, the number of wheel pulses is not within the expected range, and the absolute value of the change rate of the wheel speed between the current fault detection cycle and the previous fault detection cycle is greater than the preset change rate absolute value threshold; the abnormal sensor has wheel speed output, but the output value is abnormal. Among them, the preset vehicle speed is greater than the preset wheel speed. In this embodiment, the preset vehicle speed is 15km / h and the preset wheel speed is 2km / h.

[0079] The above-mentioned abnormal fault judgment methods include:

[0080] If the wheel speed exceeds the normal range (in this embodiment, the normal range of wheel speed is 0km / h-300km / h), the value of OutRange_cnt starts to increase from zero. If the wheel speed is within the normal range, the value of OutRange_cnt starts to decrease from zero. If the value of OutRange_cnt is greater than the maximum value of the preset wheel speed fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of OutRange_cnt is less than the minimum value of the preset wheel speed fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of OutRange_cnt is reset; if the value of OutRange_cnt is within the wheel speed fault threshold range, the wheel speed sensor is recorded as a testing state.

[0081] If the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, it is determined that the wheel speed sensor has noise, and the value of Noise_cnt starts to increase from zero. If the absolute value of the wheel speed fluctuation amplitude is less than or equal to the preset wheel speed fluctuation threshold, the value of Noise_cnt starts to decrease from zero. If the value of Noise_cnt is greater than the maximum value of the preset noise fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of Noise_cnt is less than the minimum value of the preset noise fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of Noise_cnt is reset; if the value of Noise_cnt is within the noise fault threshold range, the wheel speed sensor is recorded as a testing state.

[0082] When the ABS, EBD, TCS and other functions are not triggered during vehicle driving, if the vehicle speed is greater than 15km / h and the wheel speed is less than 2km / h, it is considered that the wheel speed is lost, and the value of WhlSpdMiss_cnt increases from zero. If the wheel speed is greater than 15km / h when the vehicle speed is greater than 15km / h, the value of WhlSpdMiss_cnt decreases from zero. If the value of WhlSpdMiss_cnt is greater than the maximum value of the preset wheel speed loss fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of WhlSpdMiss_cnt is less than the minimum value of the preset wheel speed loss fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of WhlSpdMiss_cnt is reset; if the value of WhlSpdMiss_cnt is within the wheel speed loss fault threshold range, the wheel speed sensor is recorded as a testing state.

[0083] Check the number of pulses of each wheel. If the number of pulses is not within the preset pulse number range, the value of Pluse_cnt will increase from zero. If the number of pulses is within the preset pulse number range, the value of Pluse_cnt will decrease from zero. If the value of Pluse_cnt is greater than the maximum value of the preset pulse fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of Pluse_cnt is less than the minimum value of the preset pulse loss fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of Pluse_cnt is reset; if the value of Pluse_cnt is within the pulse loss fault threshold range, the wheel speed sensor is recorded as a testing state.

[0084] The vehicle is driving on a non-bumpy road surface, and the ABS, EBD, TCS and other functions are not triggered. If the absolute value of the change rate of the wheel speed between the current cycle and the previous cycle is greater than the preset absolute value threshold of the change rate, a missing tooth occurs, and the value of Teeth_cnt increases from zero. If the absolute value of the change rate of the wheel speed between the current cycle and the previous cycle is less than or equal to the preset absolute value threshold of the change rate, the value of Teeth_cnt decreases from zero. If the value of Teeth_cnt is greater than the maximum value of the preset missing tooth fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of Teeth_cnt is less than the minimum value of the preset missing tooth fault threshold range, the wheel speed sensor is recorded as a non-fault state, and the value of Teeth_cnt is reset; if the value of Teeth_cnt is within the missing tooth fault threshold range, the wheel speed sensor is recorded as a testing state.

[0085] Further, in one embodiment, see Figure 3 As shown, when there is a failure type fault, the calculation steps of the estimated wheel speed of the failure type sensor include:

[0086] A101. If a failure type fault exists, determine whether the number of failure type sensors is less than the number of sensors in the entire vehicle. If so, proceed to step A102; if not, proceed to step A107.

[0087] A102. Determine whether there is an abnormal sensor. If so, proceed to step A103; if not, proceed to step A106.

[0088] A103. Determine whether all sensors except the failed sensor are abnormal. If so, proceed to step A104. If not, proceed to A105.

[0089] A104. The average value of the estimated wheel speeds of the abnormal sensors is used as the estimated wheel speed of each failure sensor.

[0090] A105. The average value of the estimated wheel speed of the abnormal sensor and the wheel speed of the normal sensor is used as the estimated wheel speed of each failed sensor.

[0091] A106. The remaining non-failure sensors are fault-free sensors, and the average wheel speed of the fault-free sensors is used as the estimated wheel speed of each failure sensor.

[0092] A107, obtain the vehicle acceleration in the last fault detection cycle, and calculate the estimated wheel speed of the failed sensor in combination with the wheel speed in the last fault detection cycle corresponding to the failed sensor and the vehicle speed change in the last fault detection cycle. The formula is: V wp =V wp_last +a last t,V wp_last Indicates the wheel speed of the last fault detection cycle corresponding to the failed sensor, a last Indicates the vehicle acceleration during the last fault detection cycle.

[0093] In this embodiment, when a failure type fault exists in a fault detection cycle, different wheel speed estimation methods are designed according to different situations, so that when the wheel speed sensor fails to output a wheel speed value, the wheel speed can still be obtained, effectively avoiding the situation where the wheel speed is missing.

[0094] Furthermore, in one embodiment, the above-mentioned failure type fault refers to the sensor being in an open circuit state or a short circuit state, and the sensor in the open circuit and short circuit states cannot output the wheel speed; the open circuit and short circuit states are respectively judged by the analog voltage of the sensor and the preset voltage threshold range of each state.

[0095] The judgment methods of the above-mentioned failure type faults include:

[0096] B101. Read the analog voltage of the wheel speed sensor (the wheel speed sensor generates a changing magnetic field or electromagnetic induction phenomenon by sensing the rotation of the wheel, thereby generating an electrical signal, which is then converted into an analog voltage output through circuit processing to reflect the wheel speed).

[0097] B102. If the analog voltage value is within the preset open circuit voltage threshold range, it is recorded as an open circuit state, that is, the signal is not connected or disconnected, and the value of Open_cnt starts to increase from zero. If the analog voltage value is not within the preset open circuit voltage threshold range, the value of Open_cnt starts to decrease from zero. If the value of Open_cnt is greater than the maximum value of the preset open circuit fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of Open_cnt is less than the minimum value of the preset open circuit fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of Open_cnt is reset; if the value of Open_cnt is within the open circuit fault threshold range, the wheel speed sensor is recorded as a testing state.

[0098] Furthermore, in one embodiment, the open circuit voltage threshold range may be greater than 180V and less than 220V.

[0099] B103. If the analog voltage value is within the preset short-circuit voltage threshold range, it is recorded as a short-circuit state, that is, the circuit is shorted to the power supply or shorted to the ground, and the value of Short_cnt starts to increase from zero. If the analog voltage value is not within the preset short-circuit voltage threshold range, the value of Short_cnt starts to decrease from zero. If the value of Short_cnt is greater than the maximum value of the preset short-circuit fault threshold range, the wheel speed sensor is recorded as a fault state; if the value of Short_cnt is less than the minimum value of the preset short-circuit fault threshold range, the wheel speed sensor is recorded as a non-fault state and the value of Short_cnt is reset; if the value of Short_cnt is within the short-circuit fault threshold range, the wheel speed sensor is recorded as a testing state.

[0100] Furthermore, in one embodiment, the short-circuit voltage threshold range may be greater than 230V and less than 280V.

[0101] Furthermore, in one embodiment, if the wheel speed sensor is in a testing state, the credibility of the wheel speed corresponding to the wheel speed sensor in the testing state needs to be modified to minimize the impact of the abnormal wheel speed signal on the estimation algorithm.

[0102] In a second aspect, based on the above-mentioned embodiment of the wheel speed estimation method under wheel speed sensor failure, the present application embodiment provides an embodiment of a wheel speed estimation system of the wheel speed estimation method under wheel speed sensor failure. Figure 4 As shown, the above system includes a judgment module and an estimation module, specifically:

[0103] The judgment module is used to judge the fault type of the faulty sensor when a wheel speed sensor fault occurs.

[0104] An estimation module is used to calculate the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle when only an abnormal fault exists, and calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; it is also used to use the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor when there is a failure fault and the number of failure sensors is less than the number of sensors of the whole vehicle; it is also used to calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in the vehicle speed of the previous fault detection cycle when there is a failure fault and the number of failure sensors is equal to the number of sensors of the whole vehicle.

[0105] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0106] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0107] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0108] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0109] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0110] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for estimating wheel speed when a wheel speed sensor fails, characterized in that: The method comprises: When a wheel speed sensor fault occurs, determine the fault type of the faulty sensor; If only an abnormal fault exists, the corrected wheel speed is calculated based on the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle, and the estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; If there is a failure type fault and the number of failure type sensors is less than the number of sensors in the whole vehicle, the average value of the wheel speeds measured by the non-failure type sensors shall be used as the estimated wheel speed of each failure type sensor; if the number of failure type sensors is equal to the number of sensors in the whole vehicle, the estimated wheel speed of the failure type sensor shall be calculated based on the wheel speed corresponding to the failure type sensor in the previous fault detection cycle and the change in the vehicle speed in the previous fault detection cycle.

2. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: The failure type fault refers to: The sensor is in an open circuit state or a short circuit state. The sensor in each state cannot output the wheel speed. Each state is judged by the analog voltage of the sensor and the preset voltage threshold range of each state.

3. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: The abnormal faults include: The wheel speed exceeds the normal vehicle speed range, the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, the vehicle speed is greater than the preset vehicle speed and the wheel speed is less than the preset wheel speed, the number of wheel pulses is not within the expected range, and the absolute value of the change rate of the wheel speed between the current fault detection cycle and the previous fault detection cycle is greater than the preset change rate absolute value threshold; the abnormal sensor has wheel speed output, but the output value is abnormal.

4. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: The calculating the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle includes: Determine the credibility of each wheel speed in the current fault detection cycle according to the preset fuzzy rules; The remaining wheel speeds of the vehicle except the maximum wheel speed and the minimum wheel speed are taken as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their credibility.

5. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 4, characterized in that: The step of calculating the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor comprises: According to the credibility of each wheel speed of the vehicle, the corresponding weight coefficient is calculated; Combining the corrected wheel speed, the wheel speed of the previous fault detection cycle and the weight coefficient, the linear difference method is used to calculate the estimated wheel speed of the corresponding abnormal sensor.

6. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: If there is a failure type fault, there is only a failure type sensor, and the other non-failure type sensors are fault-free sensors. When the number of failure type sensors is less than the number of sensors in the whole vehicle, the average wheel speed of the fault-free sensors is used as the estimated wheel speed of each failure type sensor.

7. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: If there is a failure type fault, there are both failed sensors and abnormal sensors. When the number of failed sensors is less than the number of sensors in the whole vehicle, the average wheel speed corresponding to the sensors except the failed sensors is used as the estimated wheel speed of each failed sensor.

8. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 7, characterized in that: The average value of the wheel speeds corresponding to the sensors other than the failed sensor is used as the estimated wheel speed of each failed sensor, including: If all sensors except the failed sensor are abnormal sensors, the average value of the estimated wheel speeds of the abnormal sensors is used as the estimated wheel speed of each failed sensor; If there are abnormal sensors and normal sensors in addition to the failed sensors, the average value of the estimated wheel speeds of the abnormal sensors and the normal sensors is taken as the estimated wheel speeds of the failed sensors.

9. The wheel speed estimation method under wheel speed sensor failure as claimed in claim 1, characterized in that: The step of calculating the estimated wheel speed of the failed sensor in combination with the wheel speed of the previous fault detection cycle corresponding to the failed sensor and the vehicle speed change in the previous fault detection cycle includes: Obtain the vehicle acceleration during the last fault detection cycle; The estimated wheel speed of the corresponding failed sensor is calculated by combining the wheel speed of the previous fault detection cycle, the vehicle acceleration of the previous fault detection cycle, and the fault detection cycle.

10. A wheel speed estimation system based on the wheel speed estimation method under wheel speed sensor failure according to any one of claims 1 to 9, characterized in that: The system comprises: A judgment module, which is used to judge the fault type of the faulty sensor when a wheel speed sensor fault occurs; An estimation module is used to calculate the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle when only an abnormal fault exists, and calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; it is also used to use the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor when there is a failure fault and the number of failure sensors is less than the number of sensors of the whole vehicle; it is also used to calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in the vehicle speed of the previous fault detection cycle when there is a failure fault and the number of failure sensors is equal to the number of sensors of the whole vehicle.

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