Vehicle speed determination method and apparatus, vehicle and readable storage medium

Abstract

This application provides a vehicle speed determination method, apparatus, vehicle, and readable storage medium. The method includes: acquiring the wheel speeds of each wheel of the vehicle; determining the overall wheel state based on the wheel speeds, where the overall wheel state characterizes the severity of wheel slippage or wheel lockup; and determining the current reference vehicle speed based on a target verification wheel speed and reference data when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state; wherein the abnormal state is a slippage state or a wheel lockup state; the target verification wheel speed corresponds to the driving state and the overall wheel state; the reference data is a target wheel speed or an integral reference vehicle speed; the target wheel speed is a wheel speed selected from the wheel speeds of each wheel based on the driving state and the overall wheel state. This application can effectively suppress integral drift and improve the estimation accuracy of the reference vehicle speed.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and in particular to a method, apparatus, vehicle, and readable storage medium for determining vehicle speed. Background Technology

[0002] Reference speed is a key parameter for vehicle driving planning, stability control, and driver assistance functions (such as U-turns, automatic parking, and drifting). Its estimation accuracy directly impacts control performance and driving safety. For example, in a cornering drift scenario, the vehicle relies on real-time reference speed to dynamically adjust the torque of each wheel to maintain the accuracy of the sideslip angle. Similarly, in emergency braking scenarios, the vehicle relies on real-time reference speed to dynamically distribute braking force.

[0003] In some embodiments, a reference vehicle speed is estimated based on the relationship between the wheel speeds of each wheel. However, this method has low accuracy and is difficult to adapt to complex operating conditions. For example, in scenarios such as emergency acceleration, emergency braking, or wheel slippage, estimating the reference vehicle speed solely based on wheel speed results in a large deviation from the actual vehicle speed, leading to low accuracy in the reference speed estimation. Summary of the Invention

[0004] This application provides a vehicle speed determination method, apparatus, vehicle, and readable storage medium, which can effectively suppress integral drift, reduce the deviation of reference vehicle speed accumulated over time, and improve the estimation accuracy of reference vehicle speed.

[0005] In a first aspect, embodiments of this application provide a vehicle speed determination method applied to a vehicle. The method includes: acquiring the wheel speeds of each wheel of the vehicle; determining the overall wheel state based on the wheel speeds of each wheel, the overall wheel state being used to characterize the severity of wheel slippage or wheel lockup; and determining the current reference vehicle speed based on a target verification wheel speed and reference data when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state; wherein the abnormal state is a slippage state or a wheel lockup state; the reference data is a target wheel speed or an integral reference vehicle speed; the target wheel speed is a wheel speed selected from the wheel speeds of each wheel based on the driving state and the overall wheel state; the target verification wheel speed corresponds to the driving state and the overall wheel state, and is determined based on wheel speeds other than the target wheel speed among the wheel speeds of each wheel; the integral reference vehicle speed is a speed estimate determined based on the vehicle's current longitudinal acceleration.

[0006] In one possible implementation, when the driving state is not a steady-state driving state but a driving state, and at least one wheel is slipping, the target verification wheel speed is the minimum verification wheel speed, which is the minimum wheel speed among all wheel speeds. The minimum verification wheel speed is used to limit the maximum boundary of vehicle speed estimation in the driving state. When the driving state is not a steady-state driving state but a braking state, and at least one wheel is locked, the target verification wheel speed is the maximum verification wheel speed, which is the maximum wheel speed among all wheel speeds. The maximum verification wheel speed is used to limit the minimum boundary of vehicle speed estimation in the braking state.

[0007] In one possible implementation, when the driving state is not a steady-state driving state but a driving state, and at least one wheel is slipping, the above-mentioned determination of the vehicle's current reference speed based on the target verification wheel speed and reference data includes: if the overall wheel state indicator indicates that some wheels are slipping, and the wheel with the minimum wheel speed is in a normal state, then the smaller of the minimum verification wheel speed and the minimum wheel speed is determined as the current reference speed; if the overall wheel state indicator indicates that some wheels are slipping, and the wheel with the minimum wheel speed is in an abnormal state, then the smaller of the minimum verification wheel speed and the integral reference speed is determined as the current reference speed.

[0008] In one possible implementation, determining the smaller of the minimum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed includes: determining a first correction parameter based on the previous reference vehicle speed; correcting the integral reference vehicle speed based on the first correction parameter to obtain a first integral reference vehicle speed; and determining the smaller of the minimum verification wheel speed and the first integral reference vehicle speed as the current reference vehicle speed.

[0009] In one possible implementation, the above-mentioned determination of the vehicle's current reference speed based on the target verification wheel speed and reference data further includes: if the overall wheel state indicates that all wheels are in a slipping state, then the smaller of the minimum verification wheel speed and the integral reference speed is determined as the current reference speed.

[0010] In one possible implementation, when the driving state is not a steady-state driving state but a braking state, and at least one wheel is locked, the above-mentioned determination of the vehicle's current reference speed based on the target verification wheel speed and reference data includes: if the overall wheel state indicator indicates that some wheels are locked, and the wheel with the maximum wheel speed is in a normal state, then the larger of the maximum verification wheel speed and the maximum wheel speed is determined as the current reference speed; if the overall wheel state indicator indicates that some wheels are locked, and the wheel with the maximum wheel speed is in an abnormal state, then the larger of the maximum verification wheel speed and the integral reference speed is determined as the current reference speed.

[0011] In one possible implementation, determining the larger of the maximum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed includes: determining a second correction parameter based on the previous reference vehicle speed; correcting the integral reference vehicle speed based on the second correction parameter to obtain a second integral reference vehicle speed; and determining the larger of the maximum verification wheel speed and the second integral reference vehicle speed as the current reference vehicle speed.

[0012] In one possible implementation, the above-mentioned determination of the vehicle's current reference speed based on the target verification wheel speed and reference data further includes: if the overall wheel status indicates that all wheels are locked, then the larger of the maximum verification wheel speed and the integral reference speed is determined as the current reference speed.

[0013] In one possible implementation, the method further includes: if there is a first reference wheel speed among the plurality of first reference wheel speeds that satisfies a first preset condition, determining a minimum verification wheel speed based on the first reference wheel speed that satisfies the first preset condition; wherein, the first reference wheel speed is any wheel speed among the wheel speeds that is less than the maximum wheel speed; the first preset condition is that the difference between the maximum wheel speed and the first reference wheel speed is greater than a first wheel speed difference threshold; if there is no first reference wheel speed among the plurality of first reference wheel speeds that satisfies the first preset condition, taking the average wheel speed of the wheel speeds of the various wheels as the minimum verification wheel speed.

[0014] In one possible implementation, the method further includes: if there is a second reference wheel speed among the multiple second reference wheel speeds that satisfies a second preset condition, determining a maximum verification wheel speed based on the second reference wheel speed that satisfies the second preset condition; wherein, the second reference wheel speed is any wheel speed among the wheel speeds that is greater than the minimum wheel speed; the second preset condition is that the difference between the second reference wheel speed and the minimum wheel speed is greater than a second wheel speed difference threshold; if there is no second reference wheel speed among the multiple second reference wheel speeds that satisfies the second preset condition, taking the average wheel speed of all wheels as the maximum verification wheel speed.

[0015] In one possible implementation, the method further includes: obtaining the vehicle's current longitudinal acceleration; adjusting the longitudinal acceleration based on the previous reference vehicle speed and the total wheel dynamic weight coefficient to obtain the adjusted longitudinal acceleration, wherein the total wheel dynamic weight coefficient is related to the wheel state of each wheel; adjusting the vehicle's current estimated acceleration based on the previous reference vehicle speed and the total wheel dynamic weight coefficient to obtain the adjusted estimated acceleration; determining the longitudinal acceleration estimate based on the adjusted longitudinal acceleration and the adjusted estimated acceleration; and determining the integral reference vehicle speed based on the longitudinal acceleration estimate and the previous reference vehicle speed using an integral method.

[0016] In one possible implementation, the above method further includes: when the driving state is a steady-state driving state, determining the maximum wheel speed and the minimum wheel speed based on the wheel speed of each wheel; if the wheel with the maximum wheel speed is in a normal state, then the maximum wheel speed is used as the current reference speed; if the wheel with the minimum wheel speed is in a normal state, then the minimum wheel speed is used as the current reference speed; if both the wheel with the maximum wheel speed and the wheel with the minimum wheel speed are in an abnormal state, then the integral reference speed is used as the current reference speed.

[0017] In one possible implementation, the method further includes: when the overall wheel status indicates that all wheels are in a normal state, using the average wheel speed of all wheels as the current reference speed.

[0018] In one possible implementation, after determining the current reference vehicle speed, the method further includes: determining the actual vehicle speed change rate based on the current reference vehicle speed and the previous reference vehicle speed; if the actual vehicle speed change rate is greater than the preset gradient limit change rate, then adjusting the current reference vehicle speed according to the preset gradient limit change rate to obtain the adjusted current reference vehicle speed; wherein, the preset gradient limit change rate is determined based on the longitudinal acceleration estimate, the total wheel dynamic weight coefficient, and the number of wheels in an abnormal state.

[0019] In one possible implementation, after adjusting the current reference vehicle speed according to the preset gradient limit change rate to obtain the adjusted current reference vehicle speed, the method further includes: constructing a transfer function using the vehicle's center frequency and damping coefficient as parameters, and filtering the adjusted current reference vehicle speed based on the transfer function to obtain the filtered current reference vehicle speed; wherein, the center frequency is determined based on the previous reference vehicle speed and the vehicle's current longitudinal acceleration; and the damping coefficient is determined based on the vehicle's current longitudinal impact and lateral impact.

[0020] In one possible implementation, determining the overall wheel state based on the wheel speeds of each wheel includes: for each wheel, determining the wheel slip ratio based on the previous reference vehicle speed and the wheel speed; determining a first predicted state corresponding to the wheel based on the wheel slip ratio; determining a second predicted state corresponding to the wheel based on the wheel acceleration and the current longitudinal acceleration of the vehicle; determining a third predicted state corresponding to the wheel based on the wheel impact intensity; determining the wheel state of each wheel based on the first, second, and third predicted states; and determining the overall wheel state based on the wheel states of each wheel.

[0021] Secondly, embodiments of this application provide a vehicle speed determining device, comprising:

[0022] The data acquisition module is used to acquire the wheel speed of each wheel of the vehicle;

[0023] The state determination module is used to determine the overall wheel state based on the wheel speed of each wheel. The overall wheel state is used to characterize the severity of wheel slippage or lockup.

[0024] The vehicle speed estimation module is used to determine the current reference vehicle speed based on the target verification wheel speed and reference data when the vehicle's driving state is not in a steady state and the overall wheel status indicates that at least one wheel is in an abnormal state.

[0025] Abnormal states include slippage or wheel lockup; reference data includes target wheel speed or integral reference speed; target wheel speed is selected from the wheel speeds of each wheel based on the driving state and overall wheel state; target verification wheel speed corresponds to the driving state and overall wheel state, and is determined based on the wheel speeds of each wheel other than the target wheel speed; integral reference speed is an estimated speed value determined based on the vehicle's current longitudinal acceleration.

[0026] Thirdly, embodiments of this application provide a vehicle, including: a memory and a processor;

[0027] The memory stores the instructions that the computer executes;

[0028] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0029] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0030] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0031] In this embodiment, when the vehicle's current driving state is not a steady-state state and at least one wheel is in an abnormal state, it indicates that the vehicle is currently in a relatively complex driving condition. In this case, based on the actual driving condition, a wheel speed that is relatively close to the overall vehicle speed is selected as the target wheel speed, which serves as a basis for vehicle speed estimation. Furthermore, a target verification wheel speed is introduced as another basis for vehicle speed estimation. Thus, the target wheel speed can represent a boundary value for vehicle speed estimation. Since the target verification wheel speed is determined based on other wheel speeds besides the target wheel speed, it can also represent another boundary value for vehicle speed estimation. Therefore, using the target wheel speed and the target verification wheel speed as two boundary values ​​to limit vehicle speed estimation restricts the reference vehicle speed to a reasonable range, reducing the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under complex conditions, and improving the accuracy of vehicle speed estimation.

[0032] Furthermore, when the target wheel speed is unreliable, the target calibration wheel speed and the target wheel speed can be used as the basis for vehicle speed estimation, thereby improving the reliability of the speed estimation. In other words, during vehicle operation, determining the target calibration wheel speed and reference data (i.e., the target wheel speed or integral reference speed) based on the vehicle's actual operating conditions (i.e., driving state and overall wheel state) can limit the reference speed to a reasonable range, effectively suppressing integral drift, reducing the deviation of the reference speed accumulated over time, and improving the accuracy and precision of the speed estimation. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0034] Figure 1 This is a schematic diagram of the arrangement of a wheel speed sensor according to an embodiment of this application;

[0035] Figure 2 A flowchart illustrating a method for determining vehicle speed provided in an embodiment of this application;

[0036] Figure 3 A flowchart illustrating another method for determining vehicle speed provided in an embodiment of this application;

[0037] Figure 4 A flowchart illustrating yet another method for determining vehicle speed provided in an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of the structure of a vehicle speed determining device provided in an embodiment of this application;

[0039] Figure 6 This is a structural schematic diagram of a vehicle provided in an embodiment of this application. Detailed Implementation

[0040] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0041] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0042] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0043] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0044] The term "module" refers to any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code that is capable of performing the functions associated with that element.

[0045] Reference speed is a key parameter for vehicle driving planning, stability control, and driver assistance functions (such as U-turns, automatic parking, and drifting). Its estimation accuracy directly impacts control performance and driving safety. For example, in a cornering drift scenario, the vehicle relies on real-time reference speed to dynamically adjust the torque of each wheel to maintain the accuracy of the sideslip angle. Similarly, in emergency braking scenarios, the vehicle relies on real-time reference speed to dynamically distribute braking force.

[0046] In some embodiments, the reference vehicle speed is estimated based on the relationship between the wheel speeds of each wheel (i.e., the wheel speed method). However, this method has low accuracy in speed estimation and is difficult to adapt to complex operating conditions. For example, in scenarios such as emergency acceleration, emergency braking, or wheel slippage, estimating the reference vehicle speed solely based on wheel speed results in a large deviation from the actual vehicle speed, leading to low accuracy in the reference vehicle speed estimation.

[0047] In some embodiments, a reference vehicle speed is obtained by integrating the longitudinal acceleration signal measured by an accelerometer. However, this method suffers from significant integration drift over time due to measurement errors in the accelerometer (such as zero-point drift and measurement noise), resulting in a large deviation from the actual vehicle speed and low accuracy in estimating the reference vehicle speed.

[0048] In some embodiments, data collected from multiple sensors such as vision, wheel speed, GPS, and IMU are fused to estimate the reference vehicle speed (i.e., the integration method). This method offers high estimation accuracy, but the algorithm is complex and costly. Furthermore, in certain special scenarios, the accuracy of sensor measurements is affected by the environment, leading to a decrease in measurement precision and consequently, lower accuracy in the estimated reference vehicle speed. For example, in off-road, foggy, or tunnel scenarios, the measurement precision and signal strength of vision and GPS sensors are reduced due to environmental factors, resulting in lower accuracy in the estimated reference vehicle speed.

[0049] In view of this, embodiments of this application provide a method for determining vehicle speed. During vehicle operation, firstly, the wheel speeds of each wheel of the vehicle are acquired; then, based on the wheel speeds of each wheel, the wheel state of each wheel can be identified, and further, based on the wheel states of each wheel, the overall wheel state is determined; finally, combining the overall wheel state and the current driving state of the vehicle, different vehicle speed estimation strategies are used to determine the current reference vehicle speed.

[0050] Specifically, when the vehicle's driving state is not a steady-state driving state, and the overall wheel state indicates that at least one wheel is in an abnormal state, a target wheel speed can be selected from the wheel speeds of each wheel based on the driving state and the overall wheel state. Combined with the driving state and the overall wheel state, a pre-estimated target verification wheel speed can be obtained. Based on the target wheel speed, the target verification wheel speed, and / or the integral reference vehicle speed, the current reference vehicle speed can be determined.

[0051] When the vehicle is in a steady-state driving condition, the current reference speed can be selected from the three options: maximum wheel speed, minimum wheel speed, or integral reference speed, based on the wheel status of each wheel.

[0052] When all wheels are in normal condition, the average wheel speed of all wheels can be used as the current reference speed.

[0053] Understandably, in practical applications, the current reference vehicle speed is determined by combining the overall wheel status and the vehicle's current driving state according to a preset speed estimation cycle. The speed estimation cycle refers to the operating cycle of the speed determination method provided in this embodiment, i.e., the time interval between acquiring sensor data and executing the algorithm. For example, the speed estimation cycle can be 10ms or 20ms.

[0054] In this embodiment, when the vehicle's current driving state is not a steady-state state and at least one wheel is in an abnormal state, it indicates that the vehicle is currently in a relatively complex driving condition. In this case, based on the actual driving condition, a wheel speed that is relatively close to the overall vehicle speed is selected as the target wheel speed, which serves as a basis for vehicle speed estimation. Furthermore, a target verification wheel speed is introduced as another basis for vehicle speed estimation. Thus, the target wheel speed can represent a boundary value for vehicle speed estimation. Since the target verification wheel speed is determined based on other wheel speeds besides the target wheel speed, it can also represent another boundary value for vehicle speed estimation. Therefore, using the target wheel speed and the target verification wheel speed as two boundary values ​​to limit vehicle speed estimation restricts the reference vehicle speed to a reasonable range, reducing the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under complex conditions, and improving the accuracy of vehicle speed estimation.

[0055] Furthermore, when the target wheel speed is unreliable, the target calibration wheel speed and the target wheel speed can be used as the basis for vehicle speed estimation, thereby improving the reliability of the speed estimation. In other words, during vehicle operation, determining the target calibration wheel speed and reference data (i.e., the target wheel speed or integral reference speed) based on the vehicle's actual operating conditions (i.e., driving state and overall wheel state) can limit the reference speed to a reasonable range, effectively suppressing integral drift, reducing the deviation of the reference speed accumulated over time, and improving the accuracy and precision of the speed estimation.

[0056] For example, when the vehicle's driving state is not a steady-state driving state, and the overall wheel state indicates that at least one wheel is in an abnormal state, a target wheel speed is selected from the wheel speeds of each wheel based on the driving state and the overall wheel state. The current reference vehicle speed is determined based on the target wheel speed, the target calibration wheel speed, and / or the integral reference vehicle speed. This can effectively suppress integral drift, reduce the deviation of the reference vehicle speed accumulated over time, and improve the accuracy of vehicle speed estimation.

[0057] For example, when the vehicle is in a steady-state driving state, based on the wheel state of each wheel, one of the three options—maximum wheel speed, minimum wheel speed, or integral reference speed—can be selected as the current reference speed. This can improve the accuracy of speed estimation, reduce algorithm complexity, and increase processing speed.

[0058] For example, when all wheels are in normal condition, the average wheel speed of all wheels is used as the current reference speed. This ensures the accuracy of speed estimation while further reducing algorithm complexity and improving processing speed.

[0059] Before introducing the vehicle speed determination method provided in the embodiments of this application, the arrangement of the sensors in the embodiments of this application will be illustrated.

[0060] In the embodiments of this application, such as Figure 1 As shown, wheel speed sensors are installed on the vehicle, such as a left front wheel speed sensor 11 on the left front wheel, a right front wheel speed sensor 12 on the right front wheel, a left rear wheel speed sensor 13 on the left rear wheel, and a right rear wheel speed sensor 14 on the right rear wheel. The wheel speeds of each wheel are collected by these sensors, namely the wheel speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel. Based on the wheel speeds, the wheel state of each wheel can be identified, and then the overall wheel state can be determined. After determining the overall wheel state, the current reference vehicle speed is determined by combining the overall wheel state with the vehicle's current driving state using different speed estimation strategies.

[0061] In some examples, the vehicle is also equipped with a longitudinal acceleration sensor, a lateral acceleration sensor, and a yaw rate sensor. The longitudinal acceleration sensor collects the vehicle's longitudinal acceleration, the lateral acceleration sensor collects the vehicle's lateral acceleration, and the yaw rate sensor collects the vehicle's yaw rate. For example... Figure 1 As shown, longitudinal acceleration refers to the acceleration of a vehicle in the direction of travel, lateral acceleration refers to the acceleration of a vehicle perpendicular to the direction of travel, and yaw rate refers to the angular velocity of a vehicle rotating about its vertical axis.

[0062] In this embodiment, the integral reference vehicle speed can be determined based on longitudinal acceleration, and this integral reference vehicle speed can be used to determine the vehicle's current reference vehicle speed. Based on longitudinal and lateral acceleration, post-processing such as smoothing filtering can be applied to the estimated current reference vehicle speed. Based on yaw rate, steering compensation processing can be performed on the acquired wheel speed.

[0063] The method for determining vehicle speed provided in this application embodiment will be described in detail below with reference to the accompanying drawings and application scenarios.

[0064] Figure 2 This is a flowchart illustrating a vehicle speed determination method provided in an embodiment of this application. Figure 2 As shown, the method for determining vehicle speed may include the following steps:

[0065] S201, obtain the wheel speed of each wheel of the vehicle.

[0066] Here, wheel speed refers to the real-time angular velocity of wheel rotation. Specifically, the wheel speed of each wheel can be collected in real time by wheel speed sensors placed on each wheel, namely the wheel speed of the left front wheel, the wheel speed of the right front wheel, the wheel speed of the left rear wheel, and the wheel speed of the right rear wheel.

[0067] In some embodiments, after acquiring the wheel speed of each wheel, the wheel speed of each wheel is preprocessed to obtain a preprocessed wheel speed. For example, low-pass filtering and mean filtering can be applied to the wheel speed to obtain the preprocessed wheel speed. Thus, preprocessing the wheel speed after acquisition can eliminate high-frequency noise signals caused by sensor circuit interference, vibration, etc., and correct long-term drift of the wheel speed signal, improving the smoothness of the wheel speed signal and thereby improving the accuracy of subsequent wheel state recognition.

[0068] For details on the specific implementation of wheel speed preprocessing, please refer to section 1.1, "Preprocessing of Sensor Signals," below. It will not be repeated here.

[0069] In some embodiments, after obtaining the wheel speed of each wheel, a compensation process is performed on the wheel speed of each wheel to obtain a compensated wheel speed. For example, for each wheel speed, the current actual torque of that wheel is obtained; time compensation is performed on the wheel speed based on the current actual torque; tire rubber hysteresis compensation is performed on the wheel speed based on the current actual torque; and steering compensation is performed on the wheel speed based on the current yaw rate of the vehicle to obtain the compensated wheel speed.

[0070] Optionally, when compensating for wheel speed, the pre-processed wheel speed can be compensated after pre-processing to obtain the compensated wheel speed.

[0071] For details on the specific implementation of wheel speed compensation, please refer to section 1.2 Wheel Speed ​​Compensation (i.e., Wheel Speed ​​Sensor Compensation) below, which will not be elaborated here.

[0072] S202, determine the overall wheel status based on the wheel speed of each wheel. The overall wheel status is used to characterize the severity of wheel slippage or lock-up.

[0073] Specifically, the wheel state of each wheel is determined based on its speed, and the overall wheel state of the vehicle is determined based on the wheel state of each wheel.

[0074] The wheel status is used to indicate whether the wheel is slipping or locked. For example, the wheel status can include normal and abnormal states, with abnormal states being slipping or locked.

[0075] For example, the overall wheel state can include a fully normal state (also known as a non-slipping and non-locking state), a fully slipping state, a fully locked state, a partially slipping state (also known as a partial slipping state), and a partially locked state (also known as a partial locking state). A fully normal state means that each wheel is in a normal state, i.e., none of the wheels are slipping or locked. A fully slipping state means that each wheel is slipping. A fully locked state means that each wheel is locked. A partially slipping state means that some wheels are slipping. A partially locked state means that some wheels are locked.

[0076] In some examples, for each wheel, the wheel acceleration and wheel impact are determined based on the wheel speed; the wheel slip ratio is determined based on the previous reference vehicle speed and the wheel speed; and the wheel state is determined based on the wheel slip ratio, wheel acceleration, and wheel impact.

[0077] After determining the wheel status of each wheel, if all wheels are in a normal state, the overall wheel status is determined to be a full-wheel normal state; if all wheels are in a slipping state, the overall wheel status is determined to be a full-wheel slipping state; if all wheels are in a locked state, the overall wheel status is determined to be a full-wheel locked state; if some wheels are in a slipping state, the overall wheel status is determined to be a partial-wheel slipping state; if some wheels are in a locked state, the overall wheel status is determined to be a partial-wheel locked state.

[0078] In some examples, taking any wheel as an example, determining the wheel state based on the wheel's slip ratio, wheel acceleration, and wheel impact can include: determining a first predicted state for the wheel based on the wheel's slip ratio; determining a second predicted state for the wheel based on the wheel's wheel acceleration and the vehicle's current longitudinal acceleration; determining a third predicted state for the wheel based on the wheel's wheel impact; and determining the wheel state based on the first, second, and third predicted states.

[0079] The first predicted state (also known as slip prediction slip state) characterizes whether the wheel may slip or lock due to a high slip ratio. The second predicted state (also known as acceleration prediction slip state) characterizes whether the wheel may slip or lock due to a large wheel acceleration. The third predicted state (also known as impact prediction slip state) characterizes whether the wheel may slip or lock due to a large wheel impact.

[0080] Optionally, the pre-processed and compensated wheel speeds can be used to determine the wheel state of each wheel, and the overall wheel state of the vehicle can be determined based on the wheel states of each wheel. This improves the accuracy of wheel state recognition, thereby more accurately determining the overall wheel state, and allowing for the selection of an appropriate vehicle speed estimation strategy to determine the current reference vehicle speed.

[0081] For details on how to determine the overall wheel state, please refer to section 1.31 below for the process of determining the overall wheel state; it will not be repeated here.

[0082] In some examples, after determining the wheel state, the dynamic weight coefficient of the wheel can be determined based on the second and third predicted states corresponding to the wheel; based on the dynamic weight coefficients of each wheel, the total dynamic weight coefficient of the wheels can be determined.

[0083] Specifically, the method for determining the dynamic weight coefficient of the wheel can be found in section 1.4 below, which describes the process of determining the dynamic weight coefficient of the wheel. It will not be repeated here.

[0084] In some examples, after determining the wheel state of each wheel, the number of target wheels is determined based on the wheel state of each wheel. The target wheels refer to the wheels that are slipping or locked (i.e., the wheel state is abnormal).

[0085] In some embodiments, the method may further include: determining the current driving state of the vehicle. The driving state of the vehicle can characterize the current actual driving conditions of the vehicle. For example, the driving state of the vehicle includes braking state, steady-state driving state, and driving state.

[0086] In some examples, the vehicle's longitudinal acceleration, longitudinal driving force, and longitudinal braking force are obtained; based on the vehicle's longitudinal acceleration, longitudinal driving force, and longitudinal braking force, the vehicle's current driving state is determined.

[0087] For details on how to determine the driving status of a vehicle, please refer to section 1.32, "Determining the Driving Status of a Vehicle," which will not be repeated here.

[0088] S203, when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state, determine the vehicle's current reference speed based on the target verification wheel speed and reference data.

[0089] In this embodiment, after determining the vehicle's current driving state and overall wheel state, a corresponding vehicle speed estimation strategy can be adopted to determine the current reference vehicle speed based on the current driving state and overall wheel state. The current reference vehicle speed refers to the reference vehicle speed determined within the current vehicle speed estimation period.

[0090] It should be noted that in this embodiment, the vehicle state can also be used to characterize the combination of the vehicle's current driving state and the overall wheel state. Then, based on the vehicle's current state, a corresponding vehicle speed estimation strategy is adopted to determine the current reference vehicle speed.

[0091] The following is an illustrative explanation of the process for determining the current reference vehicle speed under different vehicle states (i.e., different driving states and overall wheel states).

[0092] In some embodiments, when the vehicle's driving state is not a steady-state driving state, and the overall wheel state indicates that at least one wheel is in an abnormal state (i.e., the wheel state of at least one wheel is abnormal), the current reference vehicle speed is determined based on the target verification wheel speed and reference data (i.e., S203 above). The reference data is either the target wheel speed or the integral reference vehicle speed.

[0093] In this embodiment, the vehicle's driving state includes braking, steady-state driving, and driving. A vehicle's driving state is not a steady-state driving state; that is, the vehicle's driving state is either driving or braking. At least one wheel is in an abnormal state, that is, at least one wheel is either slipping or locked. Generally, when the vehicle is in driving mode, the abnormal state of the wheel is called slipping. When the vehicle is in braking mode, the abnormal state of the wheel is called locking.

[0094] Both the target wheel speed and the target verification wheel speed are determined based on the vehicle's current driving state and the overall wheel state. The target wheel speed is selected from the wheel speeds of each wheel based on the vehicle's current driving state and the overall wheel state. The target verification wheel speed is determined based on the wheel speeds of all wheels except the target wheel speed. The target wheel speed and the target verification wheel speed define the boundaries of the final estimated reference vehicle speed.

[0095] For example, when a vehicle is in a driving state and at least one wheel is slipping (i.e., in an abnormal state), the wheel speed is usually greater than the overall vehicle speed. In this case, the target wheel speed is the minimum wheel speed among all wheel speeds, and the target verification wheel speed is the minimum verification wheel speed. The minimum verification wheel speed is determined based on the wheel speeds of all wheels other than the minimum wheel speed. The minimum wheel speed is used to define the minimum boundary for vehicle speed estimation under driving conditions, and the minimum verification wheel speed is used to define the maximum boundary for vehicle speed estimation under driving conditions.

[0096] For example, when a vehicle is braking and at least one wheel is locked (i.e., in an abnormal state), the wheel speed is typically less than the overall vehicle speed. In this case, the target wheel speed is the maximum wheel speed among all wheel speeds, and the target verification wheel speed is the maximum verification wheel speed. The maximum verification wheel speed is determined based on the wheel speeds of all wheels other than the maximum wheel speed. The maximum wheel speed is used to define the maximum boundary for vehicle speed estimation under driving conditions, and the maximum verification wheel speed is used to define the minimum boundary for vehicle speed estimation under driving conditions.

[0097] The integral reference speed is a speed estimate determined based on the vehicle's current longitudinal acceleration. Specifically, it can be determined based on the previous reference speed (i.e., the reference speed determined in the previous speed estimation cycle) and the longitudinal acceleration estimate.

[0098] In this embodiment, when the vehicle's current driving state is not a steady-state state and at least one wheel is in an abnormal state, it indicates that the vehicle is currently in a relatively complex driving condition. In this case, based on the actual driving condition, a wheel speed that is relatively close to the overall vehicle speed is selected as the target wheel speed, which serves as a basis for vehicle speed estimation. Furthermore, a target verification wheel speed is introduced as another basis for vehicle speed estimation. Thus, the target wheel speed can represent a boundary value for vehicle speed estimation. Since the target verification wheel speed is determined based on other wheel speeds besides the target wheel speed, it can also represent another boundary value for vehicle speed estimation. Therefore, using the target wheel speed and the target verification wheel speed as two boundary values ​​to limit vehicle speed estimation restricts the reference vehicle speed to a reasonable range, reducing the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under complex conditions, and improving the accuracy of vehicle speed estimation.

[0099] Furthermore, when the target wheel speed is unreliable, the target calibration wheel speed and the integral reference speed (CA) can be used as the basis for vehicle speed estimation, thereby improving the reliability of the speed estimation. In other words, during vehicle operation, determining the target calibration wheel speed and reference data (i.e., the target wheel speed or integral reference speed) based on the vehicle's actual operating conditions (i.e., driving state and overall wheel state) can limit the reference speed to a reasonable range, effectively suppressing integral drift, reducing the deviation of the reference speed accumulated over time, and improving the accuracy and precision of the speed estimation.

[0100] Furthermore, in this embodiment, during vehicle operation, the target wheel speed and target verification wheel speed are determined based on the actual operating conditions of the vehicle (i.e., driving state and overall wheel state). Then, the target wheel speed, target verification wheel speed, and the currently determined integral reference vehicle speed are used as the basis to estimate the current reference vehicle speed. This can match various different operating conditions, avoid the inability to cover different operating conditions due to reliance on weighted algorithms, improve the accuracy of vehicle speed estimation under different operating conditions, and avoid estimation errors caused by algorithm crashes under complex operating conditions, thus ensuring the accuracy and precision of vehicle speed estimation under complex operating conditions.

[0101] Furthermore, compared to existing methods that estimate vehicle speed using hypothetical models (such as Kalman filters), this embodiment combines the actual operating conditions of the vehicle and determines the target wheel speed and target verification wheel speed based on the current wheel speed of each wheel. Then, using the target wheel speed, target verification wheel speed, and the currently determined integral reference speed as a basis, the current reference speed is estimated. When the vehicle's driving conditions change, the current reference speed can be determined in a timely manner, ensuring the real-time performance of the speed estimation. This allows the system to adapt to complex and ever-changing driving scenarios and meet the performance requirements of subsequent vehicle control based on the reference speed.

[0102] In some examples, when the vehicle is currently in a driving state and the overall wheel status indicates that at least one wheel is slipping (i.e., driving slippage), the wheel speed is typically greater than the overall vehicle speed. In this case, the target wheel speed is the minimum wheel speed among all wheel speeds, and the target verification wheel speed is the minimum verification wheel speed. The minimum verification wheel speed is determined based on the wheel speeds of all wheels other than the minimum wheel speed. The minimum wheel speed is used to define the minimum boundary for vehicle speed estimation under driving conditions, and the minimum verification wheel speed is used to define the maximum boundary for vehicle speed estimation under driving conditions.

[0103] Thus, when the vehicle is in driving mode, the minimum wheel speed can be used to define the minimum boundary of vehicle speed estimation, while the minimum verification wheel speed, determined based on other wheel speeds besides the minimum, can be used to define the maximum boundary of vehicle speed estimation. Therefore, using the minimum wheel speed and the minimum verification wheel speed as two boundary values ​​to limit vehicle speed estimation, thereby limiting the reference vehicle speed to a reasonable range, can reduce the speed estimation error caused by large deviations between wheel speed and overall vehicle speed under driving slip conditions, and improve the accuracy of vehicle speed estimation under driving slip conditions. Furthermore, when the minimum wheel speed is unreliable, the minimum verification wheel speed and the integral reference vehicle speed can be used as the basis for vehicle speed estimation, improving the reliability of vehicle speed estimation.

[0104] In some examples, when the vehicle is in a braking state and the overall wheel status indicates that at least one wheel is locked (i.e., brake lock-up), the wheel speed is typically less than the overall vehicle speed. In this case, the target wheel speed is the maximum wheel speed among all wheel speeds, and the target verification wheel speed is the maximum verification wheel speed. The maximum verification wheel speed is determined based on the wheel speeds of all wheels other than the maximum wheel speed. The maximum wheel speed is used to define the maximum boundary of vehicle speed estimation under driving conditions, and the maximum verification wheel speed is used to define the minimum boundary of vehicle speed estimation under driving conditions.

[0105] Thus, when the vehicle is in a braking state, the maximum wheel speed can be used to define the maximum boundary of vehicle speed estimation, while the maximum verification wheel speed, determined based on other wheel speeds besides the maximum, can be used to define the minimum boundary of vehicle speed estimation. Therefore, using the maximum wheel speed and the maximum verification wheel speed as two boundary values ​​to limit the vehicle speed estimation, thereby limiting the reference vehicle speed to a reasonable range, can reduce the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under braking lock-up conditions, and improve the accuracy of vehicle speed estimation under braking lock-up conditions. Furthermore, when the maximum wheel speed is unreliable, the maximum verification wheel speed and the integral reference vehicle speed can be used as the basis for vehicle speed estimation, improving the reliability of vehicle speed estimation.

[0106] In some examples, when the vehicle is in a steady-state driving state, the current reference speed can be selected from three options: maximum wheel speed, minimum wheel speed, or integral reference speed, based on the wheel states of each wheel. This improves the accuracy of speed estimation, reduces algorithm complexity, and increases processing speed.

[0107] In some examples, when the overall wheel status indicates that all wheels are in a normal state (i.e., all wheels are in normal condition), the average wheel speed of all wheels is used as the current reference vehicle speed. This further reduces algorithm complexity and improves processing speed while maintaining the accuracy of vehicle speed estimation.

[0108] For details on how the current reference speed is implemented, please refer to section 1.5 below for the process of determining the reference speed under different operating conditions. It will not be repeated here.

[0109] In some embodiments, after determining the current reference vehicle speed under different vehicle conditions, the actual vehicle speed change rate is determined based on the current reference vehicle speed and the previous reference vehicle speed; if the actual vehicle speed change rate is greater than the preset gradient limit change rate, the current reference vehicle speed is adjusted based on the preset gradient limit change rate to obtain the adjusted current reference vehicle speed.

[0110] The preset gradient limit change rate is determined based on the longitudinal acceleration estimate, the total wheel dynamic weight coefficient, and the number of wheels in abnormal condition.

[0111] In this way, after determining the current reference speed, gradient limiting processing is applied to the current reference speed to avoid the estimated speed changing too much compared to the previous speed estimation period, thereby further improving the accuracy of the reference speed estimation.

[0112] For details on how the current reference vehicle speed is implemented, please refer to section 1.6, "Gradient Limiting Process," which will not be repeated here.

[0113] In some embodiments, a transfer function is constructed using the vehicle's center frequency and damping coefficient as parameters, and the adjusted current reference vehicle speed is filtered based on the transfer function to obtain the filtered current reference vehicle speed.

[0114] The center frequency is determined based on the previous reference vehicle speed and the vehicle's current longitudinal acceleration; the damping coefficient is determined based on the vehicle's current longitudinal and lateral impact.

[0115] In this way, after performing gradient limiting processing on the current reference vehicle speed, filtering processing on the current reference vehicle speed can ensure the smoothness and continuity of the estimated reference vehicle speed.

[0116] For details on how the current reference vehicle speed is implemented, please refer to section 1.7, "Vehicle Speed ​​Smoothing Process," which will not be repeated here.

[0117] The above is a general description of the vehicle speed determination method provided in the embodiments of this application. The following sections provide detailed explanations of the sensor signal preprocessing process, wheel speed sensor compensation process, vehicle state determination process, wheel dynamic weight coefficient determination process, reference vehicle speed determination process under different operating conditions, gradient limiting processing process, and vehicle speed smoothing processing process.

[0118] 1.1 Sensor signal preprocessing

[0119] In some embodiments, sensor data is acquired, which may include the vehicle's longitudinal acceleration, lateral acceleration, yaw acceleration, and wheel speeds of each wheel; for each sensor data point, the sensor data is preprocessed.

[0120] First, the sensor data is low-pass filtered.

[0121] For example, the sensor data is low-pass filtered according to the following formula (1).

[0122] (1)

[0123] in, This is the sensor data after low-pass filtering in the current filtering cycle (i.e., the current cycle filtered value). This is the sensor data after low-pass filtering in the previous filtering cycle (i.e., the filtered value in the previous cycle). The sensor data input for the current vehicle speed estimation cycle, i.e., the sensor data currently collected; This is the filtering period.

[0124] The filter period, being the time constant of the low-pass filter, determines its response speed to input changes. A longer filter period results in stronger filtering and a smoother signal, but also greater hysteresis.

[0125] Understandably, the sensor data input for the current vehicle speed estimation cycle can be the wheel speed of any wheel, or the vehicle's longitudinal acceleration, lateral acceleration, or yaw acceleration.

[0126] In practical applications, the filtering period, as a filtering parameter, can be adjusted according to actual needs. Optionally, the value of the filtering parameter can be greater than or equal to the vehicle speed estimation period. This ensures that the filtering period is coordinated with the sampling period of the sensor data acquired when executing the vehicle speed determination method, which can avoid increasing discrete errors, improve filtering stability, and guarantee the filtering effect, more effectively removing high-frequency noise from the sensor signal.

[0127] Specifically, the same filtering parameters can be used when performing low-pass filtering on the wheel speeds of each wheel. However, different filtering parameters can be used when performing low-pass filtering on longitudinal acceleration, lateral acceleration, and yaw acceleration.

[0128] Then, after low-pass filtering, the sensor data is subjected to mean filtering.

[0129] Specifically, a preset sliding window is used to perform mean processing on the sensor data after low-pass filtering.

[0130] For example, the sensor data is mean filtered according to the following formula (2).

[0131] (2)

[0132] in, This is the sensor data after mean filtering during the current filtering period; This refers to sensor data after low-pass filtering, such as when i=0. This represents the sensor data after low-pass filtering in the current filtering period. When i=1, This represents the sensor data after low-pass filtering in the previous filtering cycle, and so on, when i=n, This represents the low-pass filter value for the first n filtering cycles; n is the length of the preset sliding window.

[0133] In this embodiment, after acquiring sensor data, low-pass filtering is performed on the sensor data to effectively eliminate high-frequency noise signals caused by sensor circuit interference, vibration, etc. In addition, after low-pass filtering, mean filtering is performed on the sensor data to correct long-term drift of sensor signals and improve the smoothness of sensor data.

[0134] 1.2 Wheel speed sensor compensation process

[0135] In some embodiments, after obtaining the wheel speed of each wheel, a compensation process is performed on the wheel speed of each wheel to obtain a compensated wheel speed. For example, for each wheel speed, the current actual torque of that wheel is obtained; time compensation is performed on the wheel speed based on the current actual torque; tire rubber hysteresis compensation is performed on the wheel speed based on the current actual torque; and steering compensation is performed on the wheel speed based on the current yaw rate of the vehicle to obtain the compensated wheel speed.

[0136] For example, such as Figure 3 As shown, the process of compensating for the wheel speed of any wheel may include the following steps:

[0137] S301, obtains the current actual torque of the wheel.

[0138] S302 obtains the first compensation value based on the wheel speed and actual torque.

[0139] The first compensation value is used to compensate for the phase lag generated during the denoising (low-pass filtering) process. Specifically, a correspondence between the compensation value used for time-based compensation, wheel speed, and actual wheel torque can be pre-established, and then the first compensation value can be obtained by looking up a table based on the current wheel speed and actual torque.

[0140] Based on this, the first compensation value corresponding to the wheel speed of each wheel can be determined by looking up a table. For example, the first compensation value can be expressed as... ;when hour, This indicates the first compensation value corresponding to the left front wheel speed; when hour, This represents the first compensation value corresponding to the right front wheel speed; when hour, This represents the first compensation value corresponding to the left rear wheel speed; when hour, This represents the first compensation value corresponding to the right rear wheel speed.

[0141] S303 obtains a second compensation value based on the wheel speed and actual torque.

[0142] The second compensation value is used to compensate for tire rubber hysteresis. Specifically, a correspondence between the compensation value for tire rubber hysteresis compensation, wheel speed, and actual wheel torque can be pre-established, and then the second compensation value can be obtained by looking up a table based on the current wheel speed and actual torque.

[0143] Based on this, the second compensation value corresponding to the wheel speed of each wheel can be determined by looking up a table. For example, the second compensation value can be expressed as... ;when hour, This represents the second compensation value corresponding to the left front wheel speed; when hour, This indicates the second compensation value corresponding to the right front wheel speed; when hour, This represents the second compensation value corresponding to the left rear wheel speed; when hour, This represents the second compensation value corresponding to the right rear wheel speed.

[0144] S304 determines the third compensation value based on the vehicle's current yaw rate and the distance from the center of mass to the wheel center.

[0145] The third compensation value is used to compensate for the steering system.

[0146] Specifically, using a preset vehicle steering model, a third compensation value is determined based on the vehicle's current yaw rate and the distance from the center of mass to the wheel center.

[0147] For example, the third compensation value can be determined according to the following formula (3).

[0148] (3)

[0149] in, This represents the third compensation value corresponding to the wheel speed of the i-th wheel; This indicates the vehicle's current yaw rate; This represents the component of the distance from the center of the i-th wheel to the center of mass of the vehicle in the direction perpendicular to the longitudinal axis.

[0150] Understandably, when hour, This indicates the third compensation value corresponding to the left front wheel speed; when hour, This indicates the third compensation value corresponding to the right front wheel speed; when hour, This indicates the third compensation value corresponding to the left rear wheel speed; when hour, This represents the third compensation value corresponding to the right rear wheel speed.

[0151] In this embodiment, when the vehicle turns, the radius of the outer wheel's trajectory is larger than that of the inner wheel, therefore the outer wheel speed should be higher than that of the inner wheel. Although the differential allows for different speeds of the left and right wheels, the wheel speed difference measured by the sensor includes this geometric effect. When estimating vehicle speed or determining whether the wheels are slipping, this inherent differential speed effect needs to be eliminated. Using the yaw rate and wheel position, the difference in linear velocity of each wheel relative to the center of mass can be calculated. In formula (3), the sign depends on whether the wheel is located on the inside or outside of the curve.

[0152] Specifically, when the vehicle's current yaw rate When the vehicle turns left, it indicates that the left wheels (i.e., the left front wheel and the left rear wheel) are turning left. For the right-side wheels (i.e., the right front wheel and the right rear wheel). .

[0153] When the vehicle's current yaw rate When the vehicle turns right, it indicates that the left wheels (i.e., the left front wheel and the left rear wheel) are turning right. For the right-side wheels (i.e., the right front wheel and the right rear wheel). .

[0154] Optionally, the yaw rate used here can also be the yaw rate after processing according to the sensor signal preprocessing procedure described in 1.1 above.

[0155] S305, based on the first compensation value, the second compensation value and the third compensation value, the wheel speed is compensated to obtain the compensated wheel speed.

[0156] Optionally, when performing S301 to S305 above, compensation processing can be performed on the pre-processed wheel speed.

[0157] For example, the compensated wheel speed can be determined according to the following formula (4).

[0158] (4)

[0159] in, This represents the compensated wheel speed of the i-th wheel; The wheel speed of the i-th wheel can be the wheel speed of the i-th wheel after data collection, or it can be the wheel speed of the i-th wheel after preprocessing. This represents the first compensation value corresponding to the wheel speed of the i-th wheel; This represents the second compensation value corresponding to the wheel speed of the i-th wheel; This represents the third compensation value corresponding to the wheel speed of the i-th wheel.

[0160] In this embodiment, wheel speed compensation is performed based on the first compensation value to compensate for the phase lag generated during the noise reduction (low-pass filtering) process, ensuring the real-time performance of the wheel speed signal and making the compensated wheel speed closer to the actual wheel speed changes. Wheel speed compensation based on the second compensation value compensates for tire rubber hysteresis, improving wheel speed accuracy during start-up and transient conditions, making the compensated wheel speed more realistically represent wheel rotation. Wheel speed compensation based on the third compensation value compensates for the steering system, thereby eliminating the natural difference in left and right wheel speeds caused by steering, making the compensated wheel speed more accurate.

[0161] 1.3 The process of determining the vehicle status

[0162] 1.31 Overall Wheel Condition Determination Process

[0163] In some examples, for each wheel, the wheel acceleration and wheel impact are determined based on the wheel speed; the wheel slip ratio is determined based on the previous reference vehicle speed and the wheel speed; and the wheel state is determined based on the wheel slip ratio, wheel acceleration, and wheel impact.

[0164] For example, such as Figure 4 As shown, the process of determining the overall wheel condition may include the following steps:

[0165] S401, based on the wheel speed, determine the wheel acceleration and wheel impact of the wheel.

[0166] Specifically, for any given wheel, the wheel velocity is differentiated by its first order to obtain the wheel acceleration. Wheel acceleration can represent the wheel's rotational angular acceleration.

[0167] For example, wheel acceleration can be expressed as ;when hour, This represents the wheel acceleration of the left front wheel; when hour, This represents the wheel acceleration of the right front wheel; when hour, This represents the wheel acceleration of the left rear wheel; when hour, This indicates the wheel acceleration of the right rear wheel.

[0168] Specifically, for any given wheel, the second-order differential of its wheel speed is used to obtain the wheel impact degree. The wheel impact degree can represent the rate of change of the wheel's rotational acceleration.

[0169] For example, wheel impact can be expressed as ;when hour, Indicates the wheel impact intensity of the left front wheel; when hour, Indicates the wheel impact intensity of the right front wheel; when hour, Indicates the impact intensity of the left rear wheel; when hour, This indicates the impact intensity of the right rear wheel.

[0170] It should be noted that the wheel speed here can be the wheel speed obtained after preprocessing and compensation.

[0171] S402, determine the slip ratio of the wheel based on the previous reference vehicle speed and the wheel speed.

[0172] The previous reference vehicle speed is the reference vehicle speed obtained in the previous vehicle speed estimation cycle. The wheel slip ratio can characterize the degree of wheel slippage relative to the ground.

[0173] Optionally, the slip ratio of the wheel can be determined using the wheel speed obtained after preprocessing and compensation.

[0174] For example, the slip ratio of a wheel can be determined according to the following formula (5).

[0175] (5)

[0176] in, Indicates the previous reference speed; This represents the slip ratio of the i-th wheel; it can be understood that when hour, Indicates the slip ratio of the left front wheel; when hour, Indicates the slip ratio of the right front wheel; when hour, Indicates the slip ratio of the left rear wheel; when hour, This indicates the slip ratio of the right rear wheel.

[0177] S403, determine the first predicted state corresponding to the wheel based on the wheel slip ratio.

[0178] The first predicted state (also known as the slip prediction slip state) is used to characterize whether the wheel may slip or lock up due to a high slip ratio.

[0179] For example, the absolute value of the wheel slip ratio is compared with a preset slip ratio threshold (i.e., The system compares the wheel slip ratio with the pre-set slip ratio threshold. If the absolute value of the wheel slip ratio is greater than the pre-set slip ratio threshold, the first predicted state is determined as the first state, and the state value of the first predicted state is set to 1. Otherwise, the first predicted state is determined as the second state, and the state value of the first predicted state is set to 0. It can be understood that when the first predicted state is the first state, it indicates that the wheel may slip or lock up due to a high slip ratio; when the first predicted state is the second state, it indicates that the slip ratio is low, and it is less likely to slip or lock up due to a high slip ratio.

[0180] S404, based on the wheel acceleration and the vehicle's current longitudinal acceleration, determines the second predicted state corresponding to the wheel.

[0181] The second predicted state (also known as the acceleration predicted slip state) is used to characterize whether the wheel may slip or lock up due to large wheel acceleration.

[0182] For example, the difference between the wheel acceleration and the longitudinal acceleration is determined, known as the acceleration difference; the absolute value of the acceleration difference is then compared with a preset acceleration threshold (i.e., The system compares the acceleration differences. If the absolute value of the acceleration difference is greater than a preset acceleration threshold, the second predicted state is determined to be the first state, and the state value of the second predicted state is set to 1; otherwise, the second predicted state is determined to be the second state, and the state value of the second predicted state is set to 0. It can be understood that when the second predicted state is the first state, it indicates that the wheel acceleration may be high, leading to slippage or lockup; when the second predicted state is the second state, it indicates that the wheel acceleration is low, making slippage or lockup less likely.

[0183] Optionally, the vehicle's current longitudinal acceleration can be adjusted based on the previous reference vehicle speed and the total wheel dynamic weight coefficient to obtain the adjusted longitudinal acceleration. The estimated acceleration can then be adjusted to obtain the adjusted estimated acceleration. Based on the adjusted longitudinal acceleration and the adjusted estimated acceleration, a longitudinal acceleration estimate is determined. After determining the longitudinal acceleration estimate, the difference between the wheel acceleration and the longitudinal acceleration estimate is taken as the acceleration difference. The absolute value of this acceleration difference is then compared with a preset acceleration threshold (i.e.,...). The comparison is performed, and based on the comparison results, the second predicted state corresponding to the wheel is determined.

[0184] The total wheel dynamic weight coefficient is related to the wheel state of each wheel. For details on determining the total wheel dynamic weight coefficient, please refer to section 1.4 below, "Determination of the Wheel Dynamic Weight Coefficient," which will not be repeated here.

[0185] In determining the longitudinal acceleration estimate, adjustment parameters are determined based on the previous reference vehicle speed and the total wheel dynamic weighting coefficient. These adjustment parameters are then used to adjust the current longitudinal acceleration, resulting in the adjusted longitudinal acceleration. Similarly, the adjustment parameters are used to adjust the vehicle's predicted acceleration, resulting in the adjusted predicted acceleration. Finally, the longitudinal acceleration estimate is determined based on both the adjusted longitudinal acceleration and the adjusted predicted acceleration. The adjustment parameters can serve as a confidence factor for the longitudinal acceleration sensor.

[0186] For example, the longitudinal acceleration estimate can be determined according to the following formula (6).

[0187] (6)

[0188] in, This is an estimate of the longitudinal acceleration; The longitudinal acceleration obtained in the k-th vehicle speed estimation cycle (i.e., the current vehicle speed estimation cycle); Indicates the vehicle's estimated acceleration; This indicates the adjustment parameter, namely the confidence factor for longitudinal acceleration.

[0189] When determining the estimated acceleration, the vehicle's longitudinal driving force and longitudinal braking force can be obtained, and the estimated acceleration can be determined based on the longitudinal driving force and longitudinal braking force.

[0190] For example, the estimated acceleration can be calculated according to the following formula (7).

[0191] (7)

[0192] in, Indicates longitudinal driving force. Indicates longitudinal braking force. Indicates air resistance, Indicates ramp resistance. Indicates rolling resistance, This indicates the overall weight of the vehicle.

[0193] Air resistance is related to the vehicle's current speed. In practice, air resistance can be determined based on the vehicle's current speed, frontal area, drag coefficient, and air density.

[0194] Gradient resistance is related to the vehicle's total mass and road surface gradient information. Road surface gradient information can be, for example, the slope angle. A positive slope angle indicates that the current road surface is uphill, while a negative slope angle indicates that the current road surface is downhill. In practice, gradient resistance can be determined based on the vehicle's total mass, gravitational acceleration, and road surface gradient information.

[0195] Rolling resistance is related to the rolling resistance coefficient, which is usually a constant.

[0196] It should be noted that the longitudinal acceleration here can be the longitudinal acceleration obtained after preprocessing.

[0197] In this embodiment, the current longitudinal acceleration and the estimated acceleration are adjusted according to the previous reference vehicle speed and the total wheel dynamic weight coefficient. Based on the adjusted longitudinal acceleration and the estimated acceleration, a longitudinal acceleration estimate that more reflects the actual situation can be obtained. Then, based on the wheel acceleration and the longitudinal acceleration estimate, the second predicted state corresponding to the wheel is determined, which can improve the accuracy of the prediction and thus more accurately determine the wheel state.

[0198] S405, based on the wheel impact intensity, determines the corresponding third predicted state of the wheel.

[0199] The third prediction state (also known as the impact prediction slip state) is used to characterize whether the wheel may slip or lock up due to a large wheel impact.

[0200] For example, the wheel impact intensity is determined relative to a reference longitudinal impact intensity (i.e., The difference between the two values ​​is the impact difference; the absolute value of the impact difference is compared with the preset impact threshold (i.e., The system compares the wheel impact with the preset impact threshold. If the absolute value of the wheel impact is greater than the preset impact threshold, the third predicted state is determined to be the first state, and the state value of the third predicted state is set to 1. Otherwise, the third predicted state is determined to be the second state, and the state value of the third predicted state is set to 0. It can be understood that when the third predicted state is the first state, it indicates that the wheel may slip or lock up due to a large wheel impact; when the third predicted state is the second state, it indicates that the wheel impact is low and it is not easy for the wheel to slip or lock up due to a large wheel impact.

[0201] The reference longitudinal impact can be set according to the actual situation. For example, the maximum value of the wheel impact when the vehicle is driving steadily on different road surfaces (such as asphalt road surface, cement road surface, gravel road surface, etc.) can be used to set the reference longitudinal impact.

[0202] S406, determine the wheel state of the wheel based on the first predicted state, the second predicted state, and the third predicted state.

[0203] Specifically, if the first, second, and third predicted states are all the first state, that is, the state values ​​of the first, second, and third predicted states are all 1, then the wheel state is determined to be abnormal; otherwise, the wheel state is determined to be normal.

[0204] S407 determines the overall wheel status of the vehicle based on the wheel status of each wheel.

[0205] After determining the wheel status of each wheel, if all wheels are in a normal state, the overall wheel status is determined to be a full-wheel normal state; if all wheels are in a slipping state, the overall wheel status is determined to be a full-wheel slipping state; if all wheels are in a locked state, the overall wheel status is determined to be a full-wheel locked state; if some wheels are in a slipping state, the overall wheel status is determined to be a partial-wheel slipping state; if some wheels are in a locked state, the overall wheel status is determined to be a partial-wheel locked state.

[0206] In this embodiment, for each wheel, based on the wheel slip ratio, and combined with wheel acceleration and wheel impact, the influence of vehicle pitch and road gradient on wheel status is considered. This allows for a more accurate assessment of wheel stability, improving the accuracy of wheel status recognition and thus obtaining a more realistic overall wheel status. Furthermore, based on the vehicle's driving state and the overall wheel status, target wheel speed and target verification wheel speed are determined. Then, by combining the target wheel speed, target verification wheel speed, and integral reference vehicle speed, the current reference vehicle speed is estimated. This ensures rapid response to changes in actual operating conditions while maintaining the estimated current parameter speed within a reasonable range, improving the accuracy and precision of speed estimation under different operating conditions.

[0207] 1.32 Process for determining the vehicle's driving status

[0208] In some examples, the vehicle's longitudinal acceleration, longitudinal driving force, and longitudinal braking force are obtained; based on these parameters, the vehicle's current driving state is determined. The vehicle's driving state includes braking state, steady-state driving state, and driving state.

[0209] For example, the sum of the longitudinal driving force and the longitudinal braking force is determined to obtain the current longitudinal force; the estimated acceleration is determined based on the longitudinal driving force and the longitudinal braking force; and the current driving state of the vehicle is determined based on the current longitudinal force, the longitudinal acceleration, and the estimated acceleration. The estimated acceleration can be determined according to the above formula (7).

[0210] The process of determining the vehicle's driving status is explained below.

[0211] In practical implementation, the preset range of the sum of longitudinal driving force and longitudinal braking force (i.e., longitudinal force) can be: When the current longitudinal force is less than the first threshold (i.e. When the current longitudinal force is within the braking value range, determine that the current longitudinal force is within the braking value range. When the current longitudinal force is greater than or equal to the first threshold and the current longitudinal force is less than or equal to the second threshold (i.e., When the current longitudinal force is within the steady-state driving range, determine that the current longitudinal force is within the range of values ​​for steady-state driving. When the current longitudinal force is greater than the second threshold, it is determined that the current longitudinal force is within the driving value range. .

[0212] The preset range of longitudinal acceleration can be... The current longitudinal acceleration is less than the third threshold (i.e. When the current longitudinal acceleration is within the braking range, determine that it is within the braking value range. When the longitudinal acceleration is greater than or equal to the third threshold and less than or equal to the fourth threshold (i.e., ... When the longitudinal acceleration is within the steady-state driving range, determine that the longitudinal acceleration is within the range of values ​​for steady-state driving. When the longitudinal acceleration is greater than the fourth threshold, the longitudinal acceleration is determined to be within the driving value range. .

[0213] The preset range of values ​​for the estimated acceleration can be: The current estimated acceleration is less than the fifth threshold (i.e. When the current estimated acceleration is within the braking range, determine that the current estimated acceleration is within the braking range. When the predicted acceleration is greater than or equal to the fifth threshold and less than or equal to the sixth threshold (i.e., ... When the estimated acceleration is within the steady-state driving range, determine that the estimated acceleration is within the range of values ​​for steady-state driving. When the estimated acceleration is greater than the sixth threshold, the estimated acceleration is determined to be within the driving value range. .

[0214] The current driving state of the vehicle is determined based on the current longitudinal acceleration range, the longitudinal acceleration range, and the estimated acceleration range.

[0215] For example, the range of values ​​for the current longitudinal force is the braking range. Table 1 shows the vehicle's driving state corresponding to different longitudinal accelerations and predicted accelerations.

[0216]

[0217] For example, the range of values ​​for the current longitudinal force is the steady-state driving range. Table 2 shows the vehicle's driving state corresponding to different longitudinal accelerations and predicted accelerations.

[0218]

[0219] For example, the range of values ​​for the current longitudinal force is the braking range. Table 3 shows the vehicle's driving state corresponding to different longitudinal accelerations and predicted accelerations.

[0220]

[0221] It should be noted that in Tables 1-3 above, "maintaining state" means that the vehicle's current driving state is consistent with the driving state determined in the previous speed estimation cycle. For example, if the driving state determined in the previous speed estimation cycle was a driving state, and the driving state determined in the previous speed estimation cycle was a maintaining state, then the vehicle's current driving state is determined to be a driving state.

[0222] It should also be noted that the longitudinal acceleration here can be the longitudinal acceleration obtained after preprocessing.

[0223] 1.33 Vehicle Status Determination Process

[0224] Vehicle condition refers to the combination of the vehicle's driving state and the overall wheel condition. Vehicle condition is used to characterize the severity of wheel slippage or lock-up under current actual operating conditions.

[0225] For example, the vehicle state can be determined based on the vehicle's driving state and the overall wheel state. The vehicle state can include a normal all-wheel state, a steady-state driving state, a drive slippage state, and a brake lockup state. The drive slippage state can be further divided into a partial drive slippage state (i.e., drive-side slippage) and a full drive slippage state. Similarly, the brake lockup state can be divided into a partial brake lockup state (i.e., brake-side lockup) and a full brake lockup state.

[0226] Furthermore, based on the different preset speed ranges within which the previous reference vehicle speed falls, the non-full-wheel slippage state can be divided into low-speed non-full-wheel slippage state and high-speed non-full-wheel slippage state. Similarly, based on the different preset speed ranges within which the previous reference vehicle speed falls, the non-full-wheel lockup state can be divided into low-speed braking non-full-wheel lockup state and high-speed braking non-full-wheel lockup state.

[0227] In other words, in practical applications, the vehicle state is divided into eight states: normal all-wheel state, steady-state driving state, low-speed driving non-all-wheel slipping state, high-speed driving non-all-wheel slipping state, low-speed braking non-all-wheel lock-up state, high-speed braking non-all-wheel lock-up state, driving all-wheel slipping state, and braking all-wheel lock-up state.

[0228] 1.4 The process of determining the dynamic weight coefficient of the wheel

[0229] In some examples, after determining the wheel state, the dynamic weight coefficient of the wheel can be determined based on the second and third predicted states corresponding to the wheel; based on the dynamic weight coefficients of each wheel, the total dynamic weight coefficient of the wheels can be determined.

[0230] For example, taking any wheel as an example, if the second predicted state corresponding to the wheel is the second state (i.e., the state value of the second predicted state is 0), and the third predicted state corresponding to the wheel is the second state (i.e., the state value of the third predicted state is 0), then the dynamic weight coefficient of the wheel is 0.

[0231] If either the second or third predicted state corresponding to the wheel is the first state (state value 1), then the dynamic weight coefficient of the wheel is 1.

[0232] If the second predicted state corresponding to the wheel is the first state (i.e., the state value of the second predicted state is 1), and the third predicted state corresponding to the wheel is the first state (i.e., the state value of the third predicted state is 1), then the dynamic weight coefficient of the wheel is 2.

[0233] For example, the dynamic weighting coefficients of the wheels under different second and third prediction states are shown in Table 4 below.

[0234]

[0235] For example, after assigning dynamic weight coefficients to each wheel, the sum of the dynamic weight coefficients of each wheel is used as the total dynamic weight coefficient of the wheels.

[0236] Specifically, the total wheel dynamic weight coefficient can be determined according to the following formula (8).

[0237] (8)

[0238] in, This represents the total dynamic weighting coefficient for the wheels; is the dynamic weighting coefficient of the i-th wheel.

[0239] 1.5 Determination process of reference vehicle speed under different working conditions

[0240] In this embodiment of the application, after determining the current driving state and overall wheel state of the vehicle, the current reference speed can be determined by adopting the corresponding vehicle speed estimation strategy based on the current driving state and overall wheel state.

[0241] It should be noted that in practical applications, the vehicle state can be used to characterize the combination of the vehicle's current driving state and the overall wheel state. Based on the vehicle's current driving state and the overall wheel state, a corresponding speed estimation strategy is used to determine the current reference speed. This can be understood as determining the current reference speed based on the current vehicle state and the corresponding speed estimation strategy.

[0242] The following is an illustrative explanation of the process for determining the current reference vehicle speed under different vehicle states (i.e., different driving states and overall wheel states).

[0243] In some embodiments, when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state (i.e., the wheel state of at least one wheel is in an abnormal state), the current reference vehicle speed is determined based on the target verification wheel speed and reference data (i.e., S203 above).

[0244] A vehicle's driving state includes braking, steady-state driving, and driving. A vehicle's driving state is not a steady-state driving state; that is, it is either driving or braking. At least one wheel is in an abnormal state, that is, at least one wheel is either slipping or locked. Generally, when a vehicle is in a driving state, an abnormal wheel state is called slipping. When a vehicle is in a braking state, an abnormal wheel state is called locking.

[0245] Both the target wheel speed and the target verification wheel speed are determined based on the vehicle's current driving state and the overall wheel state. The target wheel speed is selected from the wheel speeds of each wheel based on the vehicle's current driving state and the overall wheel state. The target verification wheel speed is determined based on the wheel speeds of all wheels except the target wheel speed. The target wheel speed and the target verification wheel speed define the boundaries of the final estimated reference vehicle speed.

[0246] The following is an illustrative explanation of the process for determining the current reference vehicle speed under slippery driving conditions.

[0247] In some examples, when the vehicle is currently in a driving state and the overall wheel status indicates that at least one wheel is slipping (i.e., driving slippage), the wheel speed is typically greater than the overall vehicle speed. In this case, the target wheel speed is the minimum wheel speed among all wheel speeds, and the target verification wheel speed is the minimum verification wheel speed. The minimum verification wheel speed is determined based on the wheel speeds of all wheels other than the minimum wheel speed. The minimum wheel speed is used to define the minimum boundary for vehicle speed estimation under driving conditions, and the minimum verification wheel speed is used to define the maximum boundary for vehicle speed estimation under driving conditions.

[0248] In other words, when the vehicle is currently in a driving state and at least one wheel is slipping, the minimum verification wheel speed is used as the basis for vehicle speed estimation, and the minimum wheel speed and / or the integral reference speed are used as another basis for vehicle speed estimation to determine the current reference vehicle speed. Thus, when the vehicle is in a driving state, the minimum wheel speed can be used to limit the minimum boundary of vehicle speed estimation, while the minimum verification wheel speed, determined based on other wheel speeds besides the minimum, can be used to limit the maximum boundary of vehicle speed estimation. Therefore, using the minimum wheel speed and the minimum verification wheel speed as two boundary values ​​to limit vehicle speed estimation, thereby limiting the reference vehicle speed to a reasonable range, can reduce the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under driving slippage conditions, and improve the accuracy of vehicle speed estimation under driving slippage conditions. Furthermore, when the minimum wheel speed is unreliable, the minimum verification wheel speed and the integral reference speed can be used as the basis for vehicle speed estimation to improve the reliability of vehicle speed estimation.

[0249] In some examples, when the driving state is in drive mode and the overall wheel status indicates that all wheels are slipping (i.e., all driving wheels are slipping), the smaller of the minimum check wheel speed and the integral reference speed is determined as the current reference speed.

[0250] In this embodiment, when the vehicle is in a state of all-wheel slippage, the wheel speeds are all too high and the reliability is poor. Therefore, when the minimum wheel speed is unreliable, the minimum verification wheel speed and the integral reference vehicle speed are used as the basis to determine the current reference vehicle speed, which can improve the estimation accuracy of the current reference vehicle speed.

[0251] In some examples, when the driving state is in drive mode and the overall wheel state indicator shows that some wheels are in a slipping state (i.e., the driving is not in a state of full wheel slipping), the current reference speed can be determined based on the minimum wheel speed trust state, using the minimum wheel speed or integral reference speed as a basis, and combined with the minimum verification wheel speed.

[0252] The wheel speed's trust state can include a trustworthy state and an untrustworthy state. Specifically, when the wheel to which the wheel belongs is in a normal state, the wheel speed is determined to be in a trustworthy state; when the wheel to which the wheel belongs is in an abnormal state (i.e., slipping or locking up), the wheel speed is determined to be in an untrustworthy state.

[0253] For example, if the minimum wheel speed is a reliable state (i.e., the wheel with the minimum wheel speed is in a normal state), then the smaller of the minimum verification wheel speed and the minimum wheel speed is determined as the current reference vehicle speed. In this way, since the wheel speed is higher when the vehicle slips, determining the smaller of the minimum verification wheel speed and the minimum wheel speed as the current reference vehicle speed can avoid overestimating the current reference vehicle speed and improve the estimation accuracy of the current reference vehicle speed.

[0254] For example, if the minimum wheel speed is in an unreliable state (i.e., the wheel to which the minimum wheel speed belongs is in an abnormal state), then the smaller of the minimum verification wheel speed and the integral reference speed is determined as the current reference speed. Thus, when the minimum wheel speed is in an unreliable state, using the minimum verification wheel speed and the integral reference speed as the basis for determining the current reference speed can improve the estimation accuracy of the current reference speed. Furthermore, based on the longitudinal acceleration estimate and the previous reference speed, the obtained integral reference speed is closer to the true reference speed range, which can further improve the estimation accuracy of the current reference speed.

[0255] In this embodiment, when the vehicle is in driving mode, the minimum wheel speed can be used to define the minimum boundary of vehicle speed estimation, while the minimum verification wheel speed is determined based on other wheel speeds besides the minimum wheel speed. The minimum verification wheel speed can be used to define the maximum boundary of vehicle speed estimation. Therefore, when the minimum wheel speed is reliable, using the minimum wheel speed and the minimum verification wheel speed as two boundary values ​​to limit the vehicle speed estimation keeps the reference vehicle speed within a reasonable range. This reduces the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under driving slip conditions, thus improving the accuracy of vehicle speed estimation under driving slip conditions. Furthermore, when the minimum wheel speed is unreliable, the minimum verification wheel speed and the integral reference vehicle speed can be used as the basis for vehicle speed estimation, improving the reliability of vehicle speed estimation.

[0256] Optionally, if all wheels in the overall wheel status indicator are slipping and the minimum wheel speed is unreliable, a first correction parameter can be determined based on the previous reference vehicle speed. The integral reference vehicle speed is then corrected based on this first correction parameter to obtain a first integral reference vehicle speed. The smaller of the minimum verification wheel speed and the first integral reference vehicle speed is then determined as the current reference vehicle speed. In this way, correcting the integral reference vehicle speed based on the previous reference vehicle speed, and then using the minimum verification wheel speed and the corrected first integral reference vehicle speed, improves the reliability of the integral reference vehicle speed, thereby enhancing the estimation accuracy of the current reference vehicle speed.

[0257] Specifically, when the previous reference vehicle speed is within a preset low-speed range (i.e., the vehicle is in a low-speed drive, non-full-wheel slippage state), the first correction parameter is the low-speed correction parameter (i.e., the low-speed correction factor). The low-speed correction parameter can be determined based on the current longitudinal acceleration (i.e., the longitudinal acceleration sensor value) and the previous reference vehicle speed.

[0258] For example, taking a vehicle in a low-speed driving state with non-full-wheel slippage as an example, the current reference vehicle speed can be determined according to the following formula (9).

[0259] (9)

[0260] in, This indicates the current reference vehicle speed determined under low-speed driving conditions without full-wheel slippage; Indicates the minimum check wheel speed; This indicates the low-speed correction parameter.

[0261] Specifically, when the previous reference vehicle speed is within the preset high-speed range (i.e., the vehicle is in a high-speed drive state without all-wheel slippage), the first correction parameter is the high-speed correction parameter (i.e., the high-speed correction factor). The high-speed correction parameter can be determined based on the current longitudinal acceleration (i.e., the longitudinal acceleration sensor value) and the previous reference vehicle speed.

[0262] For example, taking a vehicle in a high-speed driving non-full-wheel slip state as an example, the current reference vehicle speed can be determined according to the following formula (10).

[0263] (10)

[0264] in, This indicates the current reference vehicle speed determined under high-speed driving conditions without full-wheel slippage; Indicates the minimum check wheel speed; This indicates the high-speed correction parameter.

[0265] The following is an illustrative explanation of the process for determining the minimum test wheel speed.

[0266] Specifically, when determining the minimum check wheel speed, it can be determined based on the comparison between the first reference wheel speed and the maximum wheel speed. The first reference wheel speed is any wheel speed among all wheels that is less than the maximum wheel speed.

[0267] For example, for each first reference wheel speed, the difference between the maximum wheel speed and the first reference wheel speed (i.e., the first wheel speed difference) is determined. If the first wheel speed difference is greater than the first wheel speed difference threshold (i.e., ... If the first reference wheel speed is determined to be valid, that is, the first reference wheel speed meets the first preset condition; otherwise, the first reference wheel speed is determined to be invalid, that is, the first reference wheel speed does not meet the first preset condition.

[0268] In this regard, if there is a first reference wheel speed among multiple first reference wheel speeds that meets the first preset condition, the minimum verification wheel speed is determined based on the first reference wheel speed that meets the first preset condition.

[0269] Specifically, when the number of first reference wheel speeds that meet the first preset condition is 1, then that first reference wheel speed that meets the first preset condition is taken as the minimum verification wheel speed. When the number of first reference wheel speeds that meet the first preset condition is greater than or equal to 1, then the average value of the multiple first reference wheel speeds that meet the first preset condition is taken as the minimum verification wheel speed.

[0270] If none of the multiple first reference wheel speeds meet the first preset condition, it means that all the first reference wheel speeds are invalid, and the average wheel speed of all wheels is taken as the minimum verification wheel speed.

[0271] In this embodiment, through multiple rounds of cross-validation, abnormal wheel speeds that may be caused by slippage, lock-up, or sensor malfunction are eliminated, so that the minimum verification wheel speed can more accurately represent the true speed range of the reference vehicle speed.

[0272] In some embodiments, the integral reference speed can be determined based on the previous reference speed and the current longitudinal acceleration estimate of the vehicle.

[0273] Optionally, an integral method can be used to determine the integral reference speed based on the longitudinal acceleration estimate and the previous reference speed.

[0274] For example, the integral reference speed can be determined according to the following formula (11).

[0275] (11)

[0276] in, This represents the integral reference speed determined in the k-th speed estimation cycle (i.e., the current speed estimation cycle); This represents the longitudinal acceleration estimate determined in the k-th vehicle speed estimation cycle (i.e., the current vehicle speed estimation cycle); Indicates the previous reference speed; This represents the estimated residual value of acceleration.

[0277] The process for determining the longitudinal acceleration estimate can be found in the relevant section of S404 above, and will not be repeated here.

[0278] In this embodiment, the longitudinal acceleration estimate can more realistically reflect the actual situation. Therefore, based on the longitudinal acceleration estimate and the previous reference vehicle speed, the obtained integral reference vehicle speed is closer to the real reference speed range.

[0279] The following is an illustrative explanation of the process for determining the current reference vehicle speed under brake lock-up conditions.

[0280] In some examples, when the vehicle is in a braking state and the overall wheel status indicates that at least one wheel is locked (i.e., brake lock-up), the wheel speed is typically less than the overall vehicle speed. In this case, the target wheel speed is the maximum wheel speed among all wheel speeds, and the target verification wheel speed is the maximum verification wheel speed. The maximum verification wheel speed is determined based on the wheel speeds of all wheels other than the maximum wheel speed. The maximum wheel speed is used to define the maximum boundary of vehicle speed estimation under driving conditions, and the maximum verification wheel speed is used to define the minimum boundary of vehicle speed estimation under driving conditions.

[0281] In other words, when the vehicle is currently in a braking state and at least one wheel is locked, the maximum test wheel speed is used as the basis for vehicle speed estimation, and the maximum wheel speed or integral reference speed is used as another basis for vehicle speed estimation, thereby determining the current reference vehicle speed.

[0282] Thus, when the vehicle is in a braking state, the maximum wheel speed can be used to define the maximum boundary of vehicle speed estimation, while the maximum verification wheel speed, determined based on other wheel speeds besides the maximum, can be used to define the minimum boundary of vehicle speed estimation. Therefore, using the maximum wheel speed and the maximum verification wheel speed as two boundary values ​​to limit the vehicle speed estimation, thereby limiting the reference vehicle speed to a reasonable range, can reduce the vehicle speed estimation error caused by large deviations between wheel speed and overall vehicle speed under braking lock-up conditions, and improve the accuracy of vehicle speed estimation under braking lock-up conditions. Furthermore, when the maximum wheel speed is unreliable, the maximum verification wheel speed and the integral reference vehicle speed can be used as the basis for vehicle speed estimation, improving the reliability of vehicle speed estimation.

[0283] In some examples, when the driving state is braking and the overall wheel status indicates that all wheels are locked (i.e., all wheels are locked under braking), the larger of the maximum verification wheel speed and the integral reference speed is determined as the current reference speed.

[0284] In this embodiment, when the vehicle is in a state of full wheel lock-up, the wheel speeds are all low and the reliability is poor. Therefore, when the maximum wheel speed is unreliable, the maximum verification wheel speed and the integral reference vehicle speed are used as the basis to determine the current reference vehicle speed, which can improve the estimation accuracy of the current reference vehicle speed.

[0285] In some examples, when the driving state is braking and the overall wheel state indicator shows that some wheels are locked (i.e., braking is not full wheel lock-up), the current reference speed can be determined based on the maximum wheel speed trust state, using the maximum wheel speed or integral reference speed as a basis, and combined with the maximum verification wheel speed.

[0286] For example, if the maximum wheel speed is in a reliable state (i.e., the wheel with the maximum wheel speed is in a normal state), then the larger of the maximum verification wheel speed and the maximum wheel speed is determined as the current reference vehicle speed. In this way, since the wheel speed is low when the vehicle brakes and locks up, determining the larger of the maximum verification wheel speed and the maximum wheel speed as the current reference vehicle speed can avoid the current reference vehicle speed being estimated too low, thus improving the estimation accuracy of the current reference vehicle speed.

[0287] For example, if the maximum wheel speed is in an unreliable state (i.e., the wheel with the maximum wheel speed is in an abnormal state), the larger of the maximum verified wheel speed and the integral reference speed is determined as the current reference speed. Thus, when the maximum wheel speed is in an unreliable state, using the maximum verified wheel speed and the integral reference speed as the basis for determining the current reference speed improves the estimation accuracy of the current reference speed. Furthermore, based on the longitudinal acceleration estimate and the previous reference speed, the obtained integral reference speed is closer to the true reference speed range, further improving the estimation accuracy of the current reference speed.

[0288] In this embodiment, when the vehicle is in a braking state, the maximum wheel speed can be used to define the maximum boundary of vehicle speed estimation. The maximum verification wheel speed, determined based on other wheel speeds besides the maximum, can be used to define the minimum boundary of vehicle speed estimation. Therefore, when the maximum wheel speed is reliable, using both the maximum wheel speed and the maximum verification wheel speed as two boundary values ​​to limit the vehicle speed estimation keeps the reference speed within a reasonable range. This reduces the speed estimation error caused by large deviations between wheel speed and overall vehicle speed during brake lock-up, improving the accuracy of speed estimation under brake lock-up conditions. Furthermore, when the maximum wheel speed is unreliable, the maximum verification wheel speed and the integral reference speed can be used as the basis for speed estimation, improving the reliability of the speed estimation.

[0289] Optionally, if all wheels in the overall wheel status indicator are locked and the maximum wheel speed is unreliable, a second correction parameter can be determined based on the previous reference vehicle speed. The integral reference vehicle speed is then corrected based on this second correction parameter to obtain a second integral reference vehicle speed. The larger of the maximum verified wheel speed and the second integral reference vehicle speed is determined as the current reference vehicle speed. In this way, correcting the integral reference vehicle speed based on the previous reference vehicle speed, and then using the maximum verified wheel speed and the corrected second integral reference vehicle speed, improves the reliability of the integral reference vehicle speed, thereby enhancing the estimation accuracy of the current reference vehicle speed.

[0290] Specifically, when the previous reference vehicle speed is within the preset low-speed range (i.e., the vehicle is in a low-speed braking state without all wheels locked), the second correction parameter is the low-speed correction parameter (i.e., the low-speed correction factor). The low-speed correction parameter can be determined based on the current longitudinal acceleration (i.e., the longitudinal acceleration sensor value) and the previous reference vehicle speed.

[0291] For example, taking a vehicle in a low-speed braking non-full-wheel lock-up state as an example, the current reference vehicle speed can be determined according to the following formula (12).

[0292] (12)

[0293] in, This indicates the current reference vehicle speed determined under low-speed braking conditions where all wheels are not locked. Indicates the maximum check wheel speed; This indicates the low-speed correction parameter.

[0294] Specifically, when the previous reference vehicle speed is within the preset high-speed range (i.e., the vehicle is in a high-speed braking state without all wheels locking), the second correction parameter is the high-speed correction parameter (i.e., the high-speed correction factor). The high-speed correction parameter can be determined based on the current longitudinal acceleration (i.e., the longitudinal acceleration sensor value) and the previous reference vehicle speed.

[0295] For example, taking a vehicle in a high-speed braking non-full-wheel lock-up state as an example, the current reference vehicle speed can be determined according to the following formula (13).

[0296] (13)

[0297] in, This indicates the current reference vehicle speed determined under high-speed braking conditions without all wheels locking. Indicates the maximum check wheel speed; This indicates the high-speed correction parameter.

[0298] The following is a schematic illustration of the process for determining the maximum test wheel speed.

[0299] Specifically, when determining the maximum test wheel speed, it can be determined based on the comparison between the second reference wheel speed and the minimum wheel speed. The second reference wheel speed is any wheel speed among all wheels that is greater than the minimum wheel speed.

[0300] For example, for each second reference wheel speed, the difference between the second reference wheel speed and the minimum wheel speed (i.e., the second wheel speed difference) is determined. If the second wheel speed difference is greater than the second wheel speed difference threshold (i.e., ... If the second reference wheel speed is determined to be valid, that is, the second reference wheel speed meets the second preset condition; otherwise, the second reference wheel speed is determined to be invalid, that is, the second reference wheel speed does not meet the first preset condition.

[0301] In this regard, if there is a second reference wheel speed among multiple second reference wheel speeds that meets the second preset condition, the maximum verification wheel speed is determined based on the second reference wheel speed that meets the second preset condition.

[0302] Specifically, when the number of second reference wheel speeds that meet the second preset condition is 1, then that second reference wheel speed that meets the second preset condition is taken as the maximum verification wheel speed. When the number of second reference wheel speeds that meet the second preset condition is greater than or equal to 1, then the average value of the multiple second reference wheel speeds that meet the second preset condition is taken as the maximum verification wheel speed.

[0303] If none of the multiple second reference wheel speeds meet the second preset condition, it means that all the second reference wheel speeds are invalid, and the average wheel speed of all wheels is taken as the maximum verification wheel speed.

[0304] In this embodiment, through multiple rounds of cross-validation, abnormal wheel speeds that may be caused by slippage, lock-up, or sensor malfunction are eliminated, so that the maximum validated wheel speed can more accurately represent the true speed range of the reference vehicle speed.

[0305] The following is an illustrative explanation of the process for determining the current reference vehicle speed under steady-state driving conditions.

[0306] In some examples, when the vehicle is in a steady-state driving state, the current reference speed can be selected from the three options—maximum wheel speed, minimum wheel speed, or integral reference speed—based on the wheel states of each wheel.

[0307] For example, when the driving state is a steady-state driving state, the maximum wheel speed and the minimum wheel speed are determined based on the wheel speed of each wheel; and the current reference speed is determined based on the confidence state of the maximum wheel speed and the minimum wheel speed.

[0308] Specifically, if the wheel with the highest wheel speed is in a normal state (i.e., the highest wheel speed is a reliable state), the highest wheel speed is used as the current reference speed. If the wheel with the lowest wheel speed is in a normal state (i.e., the lowest wheel speed is a reliable state), the lowest wheel speed is used as the current reference speed. If both the wheels with the highest and lowest wheel speeds are in abnormal states (i.e., both the highest and lowest wheel speeds are unreliable states), the integral reference speed is used as the current reference speed.

[0309] In addition, if both the wheel with the maximum wheel speed and the wheel with the minimum wheel speed are in normal condition (i.e., both the maximum wheel speed and the minimum wheel speed are in a reliable state), the maximum wheel speed or the minimum wheel speed can be determined as the current reference speed.

[0310] In this embodiment, when the vehicle is in a steady-state driving state, based on the wheel state of each wheel, one of the three—maximum wheel speed, minimum wheel speed, or integral reference speed—is selected as the current reference speed. This can improve the accuracy of vehicle speed estimation, reduce algorithm complexity, and increase processing speed.

[0311] The following is an illustrative explanation of the process for determining the current reference speed under normal all-wheel conditions.

[0312] In some examples, when the overall wheel status indicates that all wheels are in a normal state (i.e., all wheels are in normal condition), the average wheel speed of all wheels is used as the current reference vehicle speed. This further reduces algorithm complexity and improves processing speed while maintaining the accuracy of vehicle speed estimation.

[0313] 1.6 Gradient Limiting Process

[0314] In some embodiments, after determining the current reference vehicle speed under different vehicle conditions, the actual vehicle speed change rate is determined based on the current reference vehicle speed and the previous reference vehicle speed; if the absolute value of the actual vehicle speed change rate is greater than the preset gradient limit change rate, the current reference vehicle speed is adjusted based on the preset gradient limit change rate to obtain the adjusted current reference vehicle speed.

[0315] The preset gradient limit change rate is determined based on the longitudinal acceleration estimate, the total wheel dynamic weight coefficient, and the number of wheels in abnormal condition.

[0316] For example, after determining the wheel state of each wheel, the number of wheels in an abnormal state (i.e., the number of slipping wheels N) can be determined. Based on the number of slipping wheels N and the total wheel dynamic weight coefficient, a limiting correction value is determined. The sum of the longitudinal acceleration estimate and the limiting correction value is used as the preset gradient limiting change rate.

[0317] For example, the preset gradient limit change rate can be determined according to the following formula (14).

[0318] (14)

[0319] in, Indicates the preset gradient limit rate of change; This indicates the amplitude limit correction value.

[0320] Thus, after determining the current reference speed, applying gradient limiting to it avoids excessive changes in the estimated speed compared to the previous estimation period, further improving the accuracy of the reference speed estimation. Furthermore, when the vehicle is in an unstable state such as skidding, the actual speed change may be more drastic than under normal conditions. In this case, correcting the longitudinal acceleration estimate as the basis for gradient limiting avoids losing true dynamic information and improves the accuracy of the current reference speed estimation.

[0321] 1.7 Vehicle speed smoothing process

[0322] In some embodiments, a transfer function is constructed using the vehicle's center frequency and damping coefficient as parameters, and the adjusted current reference vehicle speed is filtered based on the transfer function to obtain the filtered current reference vehicle speed.

[0323] The center frequency is determined based on the previous reference vehicle speed and the vehicle's current longitudinal acceleration.

[0324] The damping coefficient is determined based on the vehicle's current longitudinal and lateral impact. For example, the vehicle's longitudinal and lateral accelerations can be obtained; the longitudinal acceleration can be differentiated to obtain the longitudinal impact; the lateral acceleration can be differentiated to obtain the lateral impact; and the vehicle's current damping coefficient can be determined based on the longitudinal and lateral impacts.

[0325] For example, a transfer function is constructed using the vehicle's center frequency and damping coefficient as parameters. This transfer function can be expressed as formula (15) below.

[0326] (15)

[0327] in, This represents the output value of the bandpass filter; This represents the input value for the bandpass filter; Indicates the center frequency; This represents the damping coefficient.

[0328] Based on this, the adjusted current reference speed can be subjected to second-order bandpass filtering according to the following formula (16) to obtain the filtered current reference speed.

[0329] (16)

[0330] in, This indicates the current reference vehicle speed after filtering; Indicates the current reference speed; This indicates the vehicle's current center frequency; This indicates the vehicle's current damping coefficient.

[0331] In this way, after performing gradient limiting processing on the current reference vehicle speed, filtering processing on the current reference vehicle speed can ensure the smoothness and continuity of the estimated reference vehicle speed.

[0332] This application also provides a vehicle speed determination device. For example... Figure 5 As shown, the vehicle speed determination device 500 includes a data acquisition module 501, a state determination module 502, and a vehicle speed estimation module 503. The data acquisition module 501 acquires the wheel speeds of each wheel of the vehicle. The state determination module 502 determines the overall wheel state based on the wheel speeds of each wheel, and the overall wheel state characterizes the severity of wheel slippage or wheel lockup. The vehicle speed estimation module 503 determines the current reference vehicle speed based on a target verification wheel speed and reference data when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state; wherein the abnormal state is a slippage state or a lockup state; the reference data is a target wheel speed or an integral reference speed; the target wheel speed is a wheel speed selected from the wheel speeds of each wheel based on the driving state and the overall wheel state; the target verification wheel speed corresponds to the driving state and the overall wheel state, and is determined based on the wheel speeds of each wheel other than the target wheel speed; the integral reference speed is a speed estimate determined based on the vehicle's current longitudinal acceleration.

[0333] In some embodiments, when the driving state is not a steady-state driving state but a driving state, and at least one wheel is slipping, the target verification wheel speed is the minimum verification wheel speed, and the target wheel speed is the minimum wheel speed among the wheel speeds of each wheel, wherein the minimum verification wheel speed is used to limit the maximum boundary of the vehicle speed estimation in the driving state.

[0334] When the driving state is not a steady-state driving state and is in a braking state, and at least one wheel is locked, the target verification wheel speed is the maximum verification wheel speed. The target wheel speed is the maximum wheel speed among all wheel speeds. The maximum verification wheel speed is used to limit the minimum boundary of vehicle speed estimation under braking conditions.

[0335] In some embodiments, when the driving state is not a steady-state driving state but a driving state, and at least one wheel is in a slipping state, the vehicle speed estimation module 503 is specifically used to: if the overall wheel state indicates that some wheels are in a slipping state, and the wheel to which the minimum wheel speed belongs is in a normal state, then the smaller of the minimum verification wheel speed and the minimum wheel speed is determined as the current reference vehicle speed; if the overall wheel state indicates that some wheels are in a slipping state, and the wheel to which the minimum wheel speed belongs is in an abnormal state, then the smaller of the minimum verification wheel speed and the integral reference vehicle speed is determined as the current reference vehicle speed.

[0336] In some embodiments, the vehicle speed estimation module 503 is specifically used to: determine a first correction parameter based on the previous reference vehicle speed; correct the integral reference vehicle speed based on the first correction parameter to obtain a first integral reference vehicle speed; and determine the smaller of the minimum verification wheel speed and the first integral reference vehicle speed as the current reference vehicle speed.

[0337] In some embodiments, the vehicle speed estimation module 503 is specifically used to: if the overall wheel state indicates that all wheels are in a slipping state, then determine the smaller of the minimum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed.

[0338] In some embodiments, when the driving state is not a steady-state driving state and is a braking state, and at least one wheel is locked, the vehicle speed estimation module 503 is specifically used to: if the overall wheel state indicates that some wheels are locked and the wheel with the maximum wheel speed is in a normal state, then the larger of the maximum verification wheel speed and the maximum wheel speed is determined as the current reference vehicle speed; if the overall wheel state indicates that some wheels are locked and the wheel with the maximum wheel speed is in an abnormal state, then the larger of the maximum verification wheel speed and the integral reference vehicle speed is determined as the current reference vehicle speed.

[0339] In some embodiments, the vehicle speed estimation module 503 is specifically used to: determine a second correction parameter based on the previous reference vehicle speed; correct the integral reference vehicle speed based on the second correction parameter to obtain a second integral reference vehicle speed; and determine the larger of the maximum verification wheel speed and the second integral reference vehicle speed as the current reference vehicle speed.

[0340] In some embodiments, the vehicle speed estimation module 503 is specifically used to: if the overall wheel state indicates that all wheels are locked, then determine the larger of the maximum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed.

[0341] In some embodiments, the vehicle speed determining device 500 further includes a wheel speed verification module, which is configured to: determine a minimum verification wheel speed based on a first reference wheel speed that satisfies a first preset condition among a plurality of first reference wheel speeds; wherein the first reference wheel speed is any wheel speed among all wheels that is less than the maximum wheel speed; the first preset condition is that the difference between the maximum wheel speed and the first reference wheel speed is greater than a first wheel speed difference threshold; and if no first reference wheel speed that satisfies the first preset condition is found among a plurality of first reference wheel speeds, the average wheel speed of all wheels is taken as the minimum verification wheel speed.

[0342] In some embodiments, the wheel speed determination module is further configured to: determine a maximum verification wheel speed based on a second reference wheel speed that satisfies a second preset condition among a plurality of second reference wheel speeds; wherein the second reference wheel speed is any wheel speed among all wheels that is greater than the minimum wheel speed; the second preset condition is that the difference between the second reference wheel speed and the minimum wheel speed is greater than a second wheel speed difference threshold; and if no second reference wheel speed satisfies the second preset condition among a plurality of second reference wheel speeds, take the average wheel speed of all wheels as the maximum verification wheel speed.

[0343] In some embodiments, the vehicle speed determination device 500 further includes an integral vehicle speed determination module, which is configured to: acquire the current longitudinal acceleration of the vehicle; adjust the longitudinal acceleration according to the previous reference vehicle speed and the total wheel dynamic weight coefficient to obtain the adjusted longitudinal acceleration, wherein the total wheel dynamic weight coefficient is related to the wheel state of each wheel; adjust the current estimated acceleration of the vehicle according to the previous reference vehicle speed and the total wheel dynamic weight coefficient to obtain the adjusted estimated acceleration; determine the longitudinal acceleration estimate based on the adjusted longitudinal acceleration and the adjusted estimated acceleration; and determine the integral reference vehicle speed based on the longitudinal acceleration estimate and the previous reference vehicle speed using an integral method.

[0344] In some embodiments, the vehicle speed estimation module 503 is further configured to: determine the maximum wheel speed and the minimum wheel speed based on the wheel speed of each wheel when the driving state is a steady-state driving state; if the wheel to which the maximum wheel speed belongs is in a normal state, then the maximum wheel speed is used as the current reference vehicle speed; if the wheel to which the minimum wheel speed belongs is in a normal state, then the minimum wheel speed is used as the current reference vehicle speed; if both the wheel to which the maximum wheel speed belongs and the wheel to which the minimum wheel speed belongs are in an abnormal state, then the integral reference vehicle speed is used as the current reference vehicle speed.

[0345] In some embodiments, the vehicle speed estimation module 503 is further configured to: when the overall wheel status indicates that all wheels are in a normal state, use the average wheel speed of each wheel as the current reference vehicle speed.

[0346] In some embodiments, the vehicle speed determination device 500 further includes a gradient limiting processing module, which is used to: determine the actual vehicle speed change rate based on the current reference vehicle speed and the previous reference vehicle speed; if the actual vehicle speed change rate is greater than the preset gradient limiting change rate, adjust the current reference vehicle speed according to the preset gradient limiting change rate to obtain the adjusted current reference vehicle speed; wherein the preset gradient limiting change rate is determined based on the longitudinal acceleration estimate, the total wheel dynamic weight coefficient, and the number of wheels in an abnormal state.

[0347] In some embodiments, the vehicle speed determination device 500 further includes a vehicle speed smoothing module, which is used to construct a transfer function using the vehicle's center frequency and damping coefficient as parameters, and to filter the adjusted current reference vehicle speed based on the transfer function to obtain the filtered current reference vehicle speed; wherein, the center frequency is determined based on the previous reference vehicle speed and the vehicle's current longitudinal acceleration; and the damping coefficient is determined based on the vehicle's current longitudinal impact and lateral impact.

[0348] In some embodiments, the state determination module 502 is specifically configured to: for each wheel, determine the wheel slip ratio based on the previous reference vehicle speed and the wheel speed; determine a first predicted state corresponding to the wheel based on the wheel slip ratio; determine a second predicted state corresponding to the wheel based on the wheel acceleration and the current longitudinal acceleration of the vehicle; determine a third predicted state corresponding to the wheel based on the wheel impact; determine the wheel state of the wheel based on the first predicted state, the second predicted state, and the third predicted state; and determine the overall wheel state based on the wheel states of each wheel.

[0349] The vehicle provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0350] Figure 6 This is a structural diagram of the vehicle provided in this application. Figure 6 As shown, the vehicle 60 provided in this embodiment includes at least one processor 601 and a memory 602. Optionally, the electronic device 60 further includes a communication component 603. The processor 601, memory 602, and communication component 603 are connected via a bus 604.

[0351] In a specific implementation, at least one processor 601 executes computer execution instructions stored in memory 602, causing at least one processor 601 to perform the above-described method.

[0352] The specific implementation process of processor 601 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0353] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0354] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0355] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0356] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0357] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0358] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0359] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0360] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0361] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0362] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0363] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0364] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0365] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for determining vehicle speed, characterized in that, Applied to vehicles, the method includes: Obtain the wheel speed of each wheel of the vehicle; The overall wheel status is determined based on the wheel speed of each wheel. The overall wheel status is used to characterize the severity of wheel slippage or lock-up. When the vehicle's driving state is not a steady-state driving state, and the overall wheel state indicates that at least one wheel is in an abnormal state, the current reference speed of the vehicle is determined based on the target verification wheel speed and reference data. The abnormal state is defined as either slippage or wheel lockup. The reference data is the target wheel speed or the integral reference speed. The target wheel speed is selected from the wheel speeds of each wheel based on the driving state and the overall wheel state. The target verification wheel speed corresponds to the driving state and the overall wheel state, and is determined based on the wheel speeds of each wheel other than the target wheel speed. The integral reference speed is an estimated speed value determined based on the vehicle's current longitudinal acceleration.

2. The method according to claim 1, characterized in that, When the driving state is not the steady-state driving state but the driving state, and at least one wheel is in the slipping state, the target verification wheel speed is the minimum verification wheel speed, and the target wheel speed is the minimum wheel speed among the wheel speeds of each wheel, wherein the minimum verification wheel speed is used to limit the maximum boundary of the vehicle speed estimation in the driving state; When the driving state is not the steady-state driving state but a braking state, and at least one wheel is in the locked state, the target verification wheel speed is the maximum verification wheel speed, and the target wheel speed is the maximum wheel speed among all wheel speeds, wherein the maximum verification wheel speed is used to limit the minimum boundary of the vehicle speed estimation under the braking state.

3. The method according to claim 2, characterized in that, When the driving state is not the steady-state driving state but is a driving state, and at least one wheel is in the slipping state, determining the current reference vehicle speed based on the target verification wheel speed and reference data includes: If the overall wheel status indicator indicates that some wheels are slipping, and the wheel with the minimum wheel speed is in a normal state, then the smaller of the minimum verification wheel speed and the minimum wheel speed is determined as the current reference speed. If the overall wheel status indicator indicates that some wheels are slipping, and the wheel with the minimum wheel speed is in an abnormal state, then the smaller of the minimum verification wheel speed and the integral reference speed is determined as the current reference speed.

4. The method according to claim 3, characterized in that, The step of determining the smaller of the minimum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed includes: Based on the previous reference vehicle speed, determine the first correction parameter; The integral reference speed is corrected according to the first correction parameter to obtain the first integral reference speed; The smaller of the minimum verification wheel speed and the first integral reference vehicle speed is determined as the current reference vehicle speed.

5. The method according to claim 3, characterized in that, The step of determining the current reference vehicle speed based on the target verification wheel speed and reference data further includes: If the overall wheel status indicates that all wheels are slipping, then the smaller of the minimum check wheel speed and the integral reference speed is determined as the current reference speed.

6. The method according to claim 2, characterized in that, When the driving state is not the steady-state driving state but a braking state, and at least one wheel is in the locked state, determining the current reference vehicle speed based on the target verification wheel speed and reference data includes: If the overall wheel status indicator indicates that some wheels are locked, and the wheel with the maximum wheel speed is in a normal state, then the larger of the maximum verification wheel speed and the maximum wheel speed is determined as the current reference speed. If the overall wheel status indicator indicates that some wheels are locked, and the wheel with the maximum wheel speed is in an abnormal state, then the larger of the maximum verification wheel speed and the integral reference speed is determined as the current reference speed.

7. The method according to claim 6, characterized in that, The step of determining the larger of the maximum verification wheel speed and the integral reference vehicle speed as the current reference vehicle speed includes: Based on the previous reference vehicle speed, determine the second correction parameter; The integral reference speed is corrected according to the second correction parameter to obtain the second integral reference speed; The larger of the maximum verification wheel speed and the second integral reference speed is determined as the current reference speed.

8. The method according to claim 6, characterized in that, The step of determining the current reference vehicle speed based on the target verification wheel speed and reference data further includes: If the overall wheel status indicates that all wheels are locked, then the larger of the maximum verification wheel speed and the integral reference speed is determined as the current reference speed.

9. The method according to claim 2, characterized in that, The method further includes: If among multiple first reference wheel speeds there is a first reference wheel speed that satisfies a first preset condition, the minimum verification wheel speed is determined based on the first reference wheel speed that satisfies the first preset condition; wherein, the first reference wheel speed is any wheel speed among all wheels that is less than the maximum wheel speed; the first preset condition is that the first wheel speed difference between the maximum wheel speed and the first reference wheel speed is greater than a first wheel speed difference threshold. If none of the plurality of first reference wheel speeds meets the first preset condition, the average wheel speed of each wheel is taken as the minimum verification wheel speed.

10. The method according to claim 2, characterized in that, The method further includes: If among multiple second reference wheel speeds there is a second reference wheel speed that satisfies a second preset condition, the maximum verification wheel speed is determined based on the second reference wheel speed that satisfies the second preset condition; wherein, the second reference wheel speed is any wheel speed among all wheels that is greater than the minimum wheel speed; the second preset condition is that the difference between the second reference wheel speed and the minimum wheel speed is greater than a second wheel speed difference threshold. If none of the plurality of second reference wheel speeds meets the second preset condition, the average wheel speed of all wheels is taken as the maximum verification wheel speed.

11. The method according to claim 1, characterized in that, The method further includes: Obtain the current longitudinal acceleration of the vehicle; Based on the previous reference vehicle speed and the total wheel dynamic weight coefficient, the longitudinal acceleration is adjusted to obtain the adjusted longitudinal acceleration, wherein the total wheel dynamic weight coefficient is related to the wheel state of each wheel. Based on the previous reference vehicle speed and the total wheel dynamic weight coefficient, the current estimated acceleration of the vehicle is adjusted to obtain the adjusted estimated acceleration. Based on the adjusted longitudinal acceleration and the adjusted predicted acceleration, determine the estimated value of longitudinal acceleration; The integral reference speed is determined using the integral method based on the estimated longitudinal acceleration and the previous reference vehicle speed.

12. The method according to any one of claims 1-11, characterized in that, The method further includes: When the driving state is the steady-state driving state, the maximum wheel speed and the minimum wheel speed are determined based on the wheel speed of each wheel; If the wheel with the maximum wheel speed is in a normal state, then the maximum wheel speed is used as the current reference vehicle speed; If the wheel with the minimum wheel speed is in a normal state, then the minimum wheel speed is used as the current reference speed. If both the wheel with the maximum wheel speed and the wheel with the minimum wheel speed are in an abnormal state, then the integral reference speed will be used as the current reference speed.

13. The method according to any one of claims 1-11, characterized in that, The method further includes: When the overall wheel status indicator shows that all wheels are in normal condition, the average wheel speed of all wheels is taken as the current reference speed.

14. The method according to any one of claims 1-11, characterized in that, After determining the current reference speed of the vehicle, the method further includes: The actual vehicle speed change rate is determined based on the current reference vehicle speed and the previous reference vehicle speed. If the actual vehicle speed change rate is greater than the preset gradient limit change rate, the current reference vehicle speed is adjusted according to the preset gradient limit change rate to obtain the adjusted current reference vehicle speed; wherein, the preset gradient limit change rate is determined based on the longitudinal acceleration estimate, the total wheel dynamic weight coefficient, and the number of wheels in abnormal state.

15. The method according to claim 14, characterized in that, After adjusting the current reference vehicle speed according to the preset gradient limit change rate to obtain the adjusted current reference vehicle speed, the method further includes: Using the vehicle's center frequency and damping coefficient as parameters, a transfer function is constructed, and based on the transfer function, the adjusted current reference vehicle speed is filtered to obtain the filtered current reference vehicle speed. The center frequency is determined based on the previous reference vehicle speed and the vehicle's current longitudinal acceleration; the damping coefficient is determined based on the vehicle's current longitudinal and lateral impact.

16. The method according to claim 1, characterized in that, Determining the overall wheel state based on the wheel speed of each wheel includes: For each wheel, the slip ratio of the wheel is determined based on the previous reference vehicle speed and the wheel speed of the wheel. Based on the slip ratio of the wheel, determine the first predicted state corresponding to the wheel; Based on the wheel acceleration and the current longitudinal acceleration of the vehicle, determine the second predicted state corresponding to the wheel; Based on the wheel impact intensity, determine the third predicted state corresponding to the wheel; The wheel state is determined based on the first predicted state, the second predicted state, and the third predicted state; The overall wheel state is determined based on the state of each individual wheel.

17. A vehicle speed determining device, characterized in that, include: The data acquisition module is used to acquire the wheel speed of each wheel of the vehicle; The state determination module is used to determine the overall wheel state based on the wheel speed of each wheel. The overall wheel state is used to characterize the severity of wheel slippage or lock-up. The vehicle speed estimation module is used to determine the current reference speed of the vehicle based on the target verification wheel speed and reference data when the vehicle's driving state is not a steady-state driving state and the overall wheel state indicates that at least one wheel is in an abnormal state. The abnormal state is defined as either slippage or wheel lockup. The reference data is the target wheel speed or the integral reference speed. The target wheel speed is selected from the wheel speeds of each wheel based on the driving state and the overall wheel state. The target verification wheel speed corresponds to the driving state and the overall wheel state, and is determined based on the wheel speeds of each wheel other than the target wheel speed. The integral reference speed is an estimated speed value determined based on the vehicle's current longitudinal acceleration.

18. A vehicle, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-16.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-16.

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