Vehicle wheel speed function control method

Abstract

The invention discloses a vehicle wheel speed function control method which comprises the following steps: in a vehicle driving process, vehicle wheel speed abnormity judgment is carried out; if it is judged that the wheel speed is abnormal due to the wheel speed fault, a first measure is executed; if it is judged that the wheel speed is abnormal when the vehicle runs under the special working condition, a second measure is executed; wherein the first measure comprises related wheel speed function degradation, and the second measure comprises function active intervention control and execution of a corresponding safety control strategy. According to the vehicle wheel speed function control method, the wheel speed signal loss, the wheel speed signal noise and the stability can be accurately recognized, the accuracy of vehicle wheel speed abnormal fault recognition is improved, and the driving safety performance of the whole vehicle is improved.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology, specifically, it relates to a method for controlling vehicle wheel speed. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the widespread application of electric motor drive systems and brake-by-wire technology has significantly improved vehicle power performance and braking response efficiency. However, this technological innovation has also introduced new electromagnetic compatibility challenges and increased complexity of driving conditions. On the one hand, the high-frequency electromagnetic radiation from the electric motor and the complex electromagnetic environment generated by the electronic control unit (ECU) of the brake-by-wire system during operation cause significant electromagnetic interference to wheel speed sensors (especially those based on the Hall effect or magnetoelectric principle), resulting in instantaneous noise or distortion in the wheel speed signal. On the other hand, due to the instantaneous torque characteristics of the electric motor and the rapid response requirements of the brake-by-wire system, the wheel speed changes in new energy vehicles during rapid acceleration, energy recovery braking, or emergency braking are much more pronounced and frequent than in traditional fuel vehicles. This causes the wheel speed signal to exhibit nonlinear and large dynamic range characteristics, making it prone to short-term jumps or abnormal fluctuations.

[0003] Existing new energy vehicles are prone to short-term wheel speed fluctuations, indicating inadequate wheel speed function strategies. Aggressive wheel speed anomaly identification filters out special driving conditions, failing to trigger timely function interventions and impacting driving safety; while conservative wheel speed anomaly identification allows wheel speed loss, noise, and instability to lead to false function triggering, also affecting driving safety.

[0004] Chinese Patent Application No. 201910881410.4 discloses a vehicle wheel speed control method, device, and electric vehicle. The method includes: when braking is detected, acquiring the vehicle's wheel speed, which includes the wheel speed of the drive wheels and the wheel speed of the driven wheels; if the speed difference between the driven wheel speed and the drive wheel speed is greater than a preset speed threshold, acquiring a reference acceleration; calculating real-time acceleration based on the vehicle's wheel speed; calculating the difference between the real-time acceleration and the reference acceleration to obtain an acceleration difference value; acquiring the torque value of the vehicle motor; and compensating the torque value of the vehicle motor based on the acceleration difference to adjust the wheel speed of the drive wheels. This allows for real-time compensation of the vehicle motor's torque value based on the vehicle's wheel speed to adjust the vehicle motor's torque value.

[0005] The aim is to provide a method for controlling vehicle wheel speed, particularly regarding how to improve the overall vehicle driving safety performance. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a vehicle wheel speed control method, with the purpose of improving the overall vehicle driving safety performance.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a vehicle wheel speed function control method, comprising:

[0008] During vehicle operation, abnormal wheel speeds are detected.

[0009] If the abnormal wheel speed is determined to be caused by a wheel speed malfunction, then the first measure shall be taken;

[0010] If the abnormal wheel speed is determined to be caused by the vehicle operating under special conditions, then the second measure shall be implemented;

[0011] The first measure includes downgrading the associated wheel speed function, and the second measure includes actively intervening in the function and executing the corresponding safety control strategy.

[0012] The types of wheel speed faults include wheel speed signal loss, wheel speed signal noise, and wheel speed signal instability.

[0013] The criteria for determining wheel speed signal loss include:

[0014] (1) The vehicle voltage is normal and the ABS or ESC function is not triggered;

[0015] (2) The speed of a single wheel is less than the first set wheel speed, but the reference speed of the whole vehicle is greater than the first set speed;

[0016] (3) The duration exceeds the first set time.

[0017] The first set wheel speed is 3 kph, the first set vehicle speed is 20 kph, and the first set time is 300 seconds.

[0018] The criteria for determining the presence of noise in the wheel speed signal include:

[0019] (1) The absolute value of the current wheel deceleration exceeds the first deceleration value;

[0020] (2) When the brake pedal is pressed effectively, the number of wheel failures reaches the first set value within a second set time or the number of wheel failures exceeds the first set value within a third set time.

[0021] (3) When the brake pedal is not pressed, the number of wheel failures reaches the second set value within the fourth set time or the number of wheel failures exceeds the second set value within the fifth set time.

[0022] The first deceleration value is 15 m / s 2 The second set time is 15 seconds, the third set time is 1 second, the fourth set time is 5 seconds, and the fifth set time is 1 second.

[0023] The first setting value and the second setting value are 4 times.

[0024] The criteria for determining unstable wheel speed signals include:

[0025] (1) When there is no functional trigger and the vehicle is braking, the deceleration gradient of the wheel speed is not less than the second deceleration gradient value.

[0026] (2) When the brake pedal is pressed and the vehicle speed is lower than the second set speed, the value of the error counter reaches the first threshold.

[0027] When the brake pedal is pressed and the vehicle speed exceeds the second set speed, the value of the error counter reaches the second threshold.

[0028] (3) The brake pedal is not pressed and the vehicle speed is lower than the second set speed, and the value of the error counter reaches the third threshold.

[0029] If the brake pedal is not pressed and the vehicle speed is higher than the second set speed, the error counter value reaches the fourth threshold.

[0030] Based on wheel deceleration, six levels are defined, ranging from 0 to 10 m / s². 3 10-20m / s 3 20-30m / s 3 30-50m / s 3 50-100m / s 3 and >100m / s 3 It also has a corresponding error counter.

[0031] The criteria for determining unstable wheel speed signals also include:

[0032] (4) Period T = 10ms, and a fault is reported when t > 5s.

[0033] The vehicle wheel speed function control method of the present invention mainly involves determining the wheel speed signal loss based on the combined voltage and function triggering conditions and the wheel speed status of the four wheels; determining the wheel speed signal noise by combining the brake pedal signal, wheel acceleration value, and fault count; and determining the wheel speed signal stability by using the wheel speed deceleration gradient, the current vehicle speed status, level differentiation, and counting. By accurately identifying wheel speed signal loss, wheel speed signal noise, and stability, the method can improve the accuracy of identifying abnormal wheel speed faults and enhance the overall vehicle driving safety performance. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more comprehensive description is provided below. The present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] This invention provides a vehicle wheel speed function control method, comprising:

[0037] During vehicle operation, abnormal wheel speeds are detected.

[0038] If the abnormal wheel speed is determined to be caused by a wheel speed malfunction, then the first measure shall be taken;

[0039] If the abnormal wheel speed is determined to be caused by the vehicle operating under special conditions, then the second measure shall be implemented;

[0040] The first measure includes downgrading the associated wheel speed function, and the second measure includes actively intervening in the function and executing the corresponding safety control strategy.

[0041] The types of wheel speed faults include wheel speed signal loss, wheel speed signal noise, and wheel speed signal instability.

[0042] The criteria for determining wheel speed signal loss include:

[0043] (1) The vehicle voltage is normal and the anti-lock braking system (ABS) or ESC (electronic stability control system) function is not triggered.

[0044] (2) The speed of a single wheel is less than the first set wheel speed, but the reference speed of the whole vehicle is greater than the first set speed;

[0045] (3) The duration exceeds the first set time.

[0046] The criteria for determining the presence of noise in the wheel speed signal include:

[0047] (1) The absolute value of the current wheel deceleration exceeds the first deceleration value;

[0048] (2) When the brake pedal is pressed effectively, the number of wheel failures reaches the first set value within a second set time or the number of wheel failures exceeds the first set value within a third set time.

[0049] (3) When the brake pedal is not pressed, the number of wheel failures reaches the second set value within the fourth set time or the number of wheel failures exceeds the second set value within the fifth set time.

[0050] The first setting value and the second setting value are 4 times.

[0051] The criteria for determining unstable wheel speed signals include:

[0052] (1) When there is no functional trigger and the vehicle is braking, the deceleration gradient of the wheel speed is not less than the second deceleration gradient value.

[0053] (2) When the brake pedal is pressed and the vehicle speed is lower than the second set speed, the value of the error counter reaches the first threshold.

[0054] When the brake pedal is pressed and the vehicle speed exceeds the second set speed, the value of the error counter reaches the second threshold.

[0055] (3) The brake pedal is not pressed and the vehicle speed is lower than the second set speed, and the value of the error counter reaches the third threshold.

[0056] If the brake pedal is not pressed and the vehicle speed is higher than the second set speed, the error counter value reaches the fourth threshold.

[0057] The criteria for determining unstable wheel speed signals also include:

[0058] (4) Period T = 10ms, and a fault is reported when t > 5s.

[0059] Example

[0060] This invention provides a method for controlling wheel speed in new energy vehicles, comprising:

[0061] During vehicle operation, abnormal wheel speeds are detected.

[0062] If the abnormal wheel speed is determined to be caused by a wheel speed malfunction, then the first measure shall be taken;

[0063] If the abnormal wheel speed is determined to be caused by the vehicle operating under special conditions, then the second measure shall be implemented.

[0064] Specifically, in this embodiment of the invention, the main focus is on determining the wheel speed signal loss based on the combined voltage and function triggering conditions and the wheel speed of the four wheels; determining the wheel speed signal noise by combining the brake pedal signal, wheel acceleration value, and number of faults; and determining the stability of the wheel speed signal by using the wheel speed deceleration gradient, the current vehicle speed status, level differentiation, and counting.

[0065] In this embodiment of the invention, when the wheel speed sensor detects an abnormality in wheel speed data during vehicle operation, the system first needs to determine the abnormality. Specifically, the determination involves distinguishing whether the abnormality is caused by a wheel speed sensor malfunction or by normal wheel speed fluctuations due to the vehicle operating under special conditions (such as low-adhesion road surfaces, muddy roads, slopes, etc.).

[0066] In this embodiment of the invention, if the system determines that the abnormal wheel speed is caused by a wheel speed sensor malfunction, the first measure to be taken includes downgrading the associated wheel speed functions and issuing a fault warning to the driver through the instrument panel or other display interface. Downgrading the associated wheel speed functions means that functions related to wheel speed will be downgraded or disabled to prevent malfunctions in the control system caused by incorrect information. This ensures basic driving safety of the vehicle in a faulty state and avoids the risks that may arise from false alarms or malfunctions.

[0067] In this embodiment of the invention, if it is determined that the abnormal wheel speed is caused by a special working condition, depending on the function trigger threshold, the second measure to be executed includes active function intervention control and execution of corresponding safety control strategies, such as anti-lock braking.

[0068] In this embodiment of the invention, the types of wheel speed faults include wheel speed signal loss, wheel speed signal noise, and wheel speed signal instability.

[0069] In this embodiment of the invention, the criteria for determining wheel speed signal loss include:

[0070] (1) The vehicle voltage is normal and the ABS or ESC function is not triggered;

[0071] (2) The speed of a single wheel is less than the first set wheel speed, but the reference speed of the whole vehicle is greater than the first set speed;

[0072] (3) The duration exceeds the first set time.

[0073] The above-mentioned judgment condition (1) for wheel speed signal loss can exclude wheel speed signal fluctuations caused by abnormal power supply or intervention of active safety systems, ensuring the accuracy of the judgment. When ABS / ESC is activated, the wheel speed may be actively adjusted (such as anti-lock braking), and under this condition, detecting signal loss can avoid false alarms.

[0074] In the above-mentioned judgment conditions (2) and (3) for wheel speed signal loss, the first set wheel speed is 3 kph, the first set vehicle speed is 20 kph, and the first set time is 300 seconds. It is required that the wheel speed of a certain wheel is <3 kph and the overall vehicle speed is >20 kph. The wheel speed signal loss is identified by the significant difference between the wheel speed and the overall vehicle speed. During normal driving, the wheel speed of a single wheel may be temporarily lower than the overall vehicle speed due to differential speed or slippage. However, extreme low speed (<3 kph) is very unusual when the overall vehicle speed is high (>20 kph). Possible reasons include: sensor failure, signal line breakage, etc. Moreover, it is required that the state where the wheel speed of a certain single wheel is less than the first set wheel speed and the overall vehicle reference speed is greater than the first set vehicle speed lasts for more than 300 seconds. The purpose is to filter out instantaneous interference (such as electromagnetic pulse, road impact), and the long duration reduces the false alarm rate, ensures the accuracy of judgment, and avoids delaying the alarm of real faults.

[0075] In this embodiment of the invention, the criteria for determining the presence of noise in the wheel speed signal include:

[0076] (1) The absolute value of the current wheel deceleration exceeds the first deceleration value;

[0077] (2) When the brake pedal is pressed effectively, the number of wheel failures reaches the first set value within a second set time or the number of wheel failures exceeds the first set value within a third set time.

[0078] (3) When the brake pedal is not pressed, the number of wheel failures reaches the second set value within the fourth set time or the number of wheel failures exceeds the second set value within the fifth set time.

[0079] In the above-mentioned judgment conditions (1) and (2) for the presence of noise in the wheel speed signal, the first deceleration value is 15 m / s. 2 The second timeout is 15 seconds, the third timeout is 1 second, and the first timeout is 4 times. If the absolute value of the wheel's deceleration exceeds 15 m / s²... 2 This may indicate the presence of noise in the wheel speed signal. In actual driving, wheel deceleration rarely changes so drastically unless extreme situations occur (such as a collision). During vehicle deceleration, the judgment condition is set as the absolute value of the current wheel deceleration exceeding the first deceleration value. Considering that the brake pedal is depressed, abnormally high deceleration may be caused by signal noise. The condition is set to detect the absolute value of the current wheel deceleration exceeding the first deceleration value four times within 15 seconds or more than four times within 1 second. Brief noise (e.g., four times per second may be caused by road bumps) is allowed, but the possibility of long-term high-frequency noise must be considered. If conditions (1) and (2) are met, it indicates that the wheel speed signal contains noise.

[0080] In the above-mentioned judgment conditions (1) and (3) for the presence of noise in the wheel speed signal, the first deceleration value is 15 m / s. 2 The fourth setting time is 5 seconds, the fifth setting time is 1 second, and the second setting value is 4 times. The judgment condition is set to the current wheel deceleration absolute value exceeding the first deceleration value. Considering that the brake pedal is not pressed, in the non-braking state, a stricter threshold is set because the wheel speed should be more stable when not braking. Therefore, it is set that the current wheel deceleration absolute value exceeds the first deceleration value 4 times within 5 seconds or the current wheel deceleration absolute value exceeds the first deceleration value more than 4 times within 1 second. If the conditions (1) and (3) are met, it indicates that there is noise in the wheel speed signal.

[0081] In the above judgment method, by combining deceleration with the frequency of fault occurrence, and balancing sensitivity and robustness, faults in wheel speed signal noise can be accurately identified.

[0082] In this embodiment of the invention, the criteria for determining unstable wheel speed signals include:

[0083] (1) When there is no functional trigger and the vehicle is braking, the deceleration gradient of the wheel speed is not less than the second deceleration gradient value.

[0084] (2) When the brake pedal is pressed and the vehicle speed is lower than the second set speed, the value of the error counter reaches the first threshold.

[0085] Alternatively, if the brake pedal is pressed and the vehicle speed exceeds the second set speed, the error counter value reaches the second threshold.

[0086] (3) The brake pedal is not pressed and the vehicle speed is lower than the second set speed, and the value of the error counter reaches the third threshold.

[0087] Alternatively, if the brake pedal is not pressed and the vehicle speed is higher than the second set speed, the error counter value reaches the fourth threshold.

[0088] (4) Period T = 10ms, and a fault is reported when the cumulative count t > 5s.

[0089] In this embodiment of the invention, the wheel deceleration is divided into six levels, ranging from 0 to 10 m / s². 3 10-20m / s 3 20-30m / s 3 30-50m / s 3 50-100m / s 3 and >100m / s 3 Different error counter increments are assigned to each level. Wheel deceleration is divided into 6 levels (0-10, 10-20, ..., >100m / s²). 3This is used to quantify the severity of faults. Low levels correspond to normal fluctuations, while high levels correspond to severe anomalies. Different error counter increments are assigned based on braking status, vehicle speed, and deceleration level. The second deceleration gradient value is 5 m / s². 3 The second set vehicle speed is 20 kph. The first threshold values ​​are -1, 4, 8, 10, 15, and 20, and the second threshold values ​​are -1, 2, 5, 10, 20, and 30. Under braking conditions, at low speeds (<20 kph), higher deceleration (e.g., 50-100 m / s²) is tolerated. 3 Only 15 is considered, as wheel speed is controlled during braking. The third threshold values ​​are -1, 2, 5, 10, 20, and 70, and the fourth threshold values ​​are -1, 2, 5, 10, 20, and 100. Under non-braking conditions, at high speeds (>20 kph), it is extremely sensitive to high deceleration (e.g., >100 m / s²). 3 (Calculated as 100), because the wheel speed should be stable when not braking.

[0090] Among the above-mentioned judgment conditions (1), (2) and (4) for the presence of noise in the wheel speed signal, the judgment condition is set to be that there is no functional trigger and the vehicle is braking, and the deceleration gradient of the wheel speed is greater than or equal to 5 m / s. 3 5m / s 3 This can be considered an abnormal threshold, used to initially screen for unstable signal events and exclude minor fluctuations. It simultaneously meets the following conditions: when the brake pedal is depressed, if the vehicle speed is below 20 kph, the six levels of error counters correspond to -1, 4, 8, 10, 15, and 20 respectively; or simultaneously meets the condition that the vehicle speed is above 20 kph, the six levels of error counters correspond to -1, 2, 5, 10, 20, and 30 respectively. A period of T = 10 ms is set for real-time counter updates. When the cumulative counting time t > 5 s, a fault is reported to avoid false alarms caused by momentary interference (such as road impact).

[0091] Among the above-mentioned judgment conditions (1), (3) and (4) for the presence of noise in the wheel speed signal, the judgment condition is set to be that there is no functional trigger and the vehicle is braking, and the deceleration gradient of the wheel speed is greater than or equal to 5 m / s. 3 Simultaneously, the following conditions must be met: the brake pedal is not depressed, the vehicle speed is below 20 kph, and the six levels of error counters are -1, 2, 5, 10, 20, and 70 respectively; or the vehicle speed is above 20 kph, and the six levels of error counters are -1, 2, 5, 10, 20, and 100 respectively. A period of T = 10 ms is set for real-time counter updates. When the cumulative counting time t > 5 s, a fault is reported to avoid false alarms due to momentary interference (such as road impact).

[0092] In the above judgment method, by using the wheel speed deceleration gradient, the current vehicle speed status, and through level differentiation and counting, the fault of unstable wheel speed signal can be accurately identified.

[0093] Compared with the prior art, the embodiments of the present invention avoid potential problems caused by the two extremes of wheel speed recognition through strategy optimization, and improve the overall vehicle driving safety by accurately identifying wheel speed loss, wheel speed noise and instability faults.

[0094] The technical solution adopted in this embodiment of the invention is based on strategy optimization of the ABS or ESC controller, and is verified by test calibration. The verification process is as follows:

[0095] S1: Wheel speed signal loss detected.

[0096] (1) The wheel speed probes of the whole vehicle are raised one by one, and there is no wheel speed output on a single wheel;

[0097] (2) Test whether wheel speed signal loss is detected;

[0098] S2: Identify wheel speed noise:

[0099] (1) The whole vehicle simulates cobblestone road conditions and performs emergency braking;

[0100] (2) Observe whether the wheel speed data is abnormal and whether the vehicle is driving normally;

[0101] S3: Unstable wheel speed signal recognition.

[0102] (1) When the positive and negative terminals of the simulated wheel speed probe are short-circuited momentarily, the wheel speed waveform is abnormal.

[0103] (2) Observe whether the wheel speed data is abnormal, and whether the vehicle can drive and brake normally.

[0104] The present invention has been described above by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A vehicle wheel speed control method, characterized in that, include: During vehicle operation, abnormal wheel speeds are detected. If the abnormal wheel speed is determined to be caused by a wheel speed malfunction, then the first measure shall be taken; If the abnormal wheel speed is determined to be caused by the vehicle operating under special conditions, then the second measure shall be implemented; The first measure includes downgrading the associated wheel speed function, and the second measure includes actively intervening in the function and executing the corresponding safety control strategy.

2. The vehicle wheel speed control method according to claim 1, characterized in that, The types of wheel speed faults include wheel speed signal loss, wheel speed signal noise, and wheel speed signal instability.

3. The vehicle wheel speed control method according to claim 2, characterized in that, The criteria for determining wheel speed signal loss include: (1) The vehicle voltage is normal and the ABS or ESC function is not triggered; (2) The speed of a single wheel is less than the first set wheel speed, but the reference speed of the whole vehicle is greater than the first set speed; (3) The duration exceeds the first set time.

4. The vehicle wheel speed control method according to claim 3, characterized in that, The first set wheel speed is 3 kph, the first set vehicle speed is 20 kph, and the first set time is 300 seconds.

5. The vehicle wheel speed control method according to claim 2, characterized in that, The criteria for determining the presence of noise in the wheel speed signal include: (1) The absolute value of the current wheel deceleration exceeds the first deceleration value; (2) When the brake pedal is pressed effectively, the number of wheel failures reaches the first set value within a second set time or the number of wheel failures exceeds the first set value within a third set time. (3) When the brake pedal is not pressed, the number of wheel failures reaches the second set value within the fourth set time or the number of wheel failures exceeds the second set value within the fifth set time.

6. The vehicle wheel speed control method according to claim 5, characterized in that, The first deceleration value is 15 m / s 2 The second set time is 15 seconds, the third set time is 1 second, the fourth set time is 5 seconds, and the fifth set time is 1 second.

7. The vehicle wheel speed control method according to claim 5, characterized in that, The first setting value and the second setting value are 4 times.

8. The vehicle wheel speed control method according to claim 2, characterized in that, The criteria for determining unstable wheel speed signals include: (1) When there is no functional trigger and the vehicle is braking, the deceleration gradient of the wheel speed is not less than the second deceleration gradient value. (2) When the brake pedal is pressed and the vehicle speed is lower than the second set vehicle speed, the value of the error counter reaches the first threshold. When the brake pedal is pressed and the vehicle speed exceeds the second set speed, the error counter value reaches the second threshold. (3) The brake pedal is not pressed and the vehicle speed is lower than the second set speed, and the value of the error counter reaches the third threshold. If the brake pedal is not pressed and the vehicle speed is higher than the second set speed, the error counter value reaches the fourth threshold.

9. The vehicle wheel speed control method according to claim 8, characterized in that, Based on wheel deceleration, six levels are defined, ranging from 0 to 10 m / s². 3 10-20m / s 3 20-30m / s 3 30-50m / s 3 50-100m / s 3 and >100m / s 3 It also has a corresponding error counter.

10. The vehicle wheel speed control method according to claim 8, characterized in that, The criteria for determining unstable wheel speed signals also include: (4) Period T = 10ms, and a fault is reported when t > 5s.