Vehicle longitudinal speed estimation method and device, vehicle and storage medium

Abstract

The invention relates to the technical field of vehicles, in particular to a vehicle longitudinal speed estimation method and device, a vehicle and a storage medium, and the method comprises the steps: obtaining the pressure of a brake master cylinder of the vehicle, the driving torque of each wheel, the rotating speed of each wheel and the acceleration of the whole vehicle; estimating the vertical force of each wheel of the vehicle according to the acceleration of the whole vehicle, and calculating the speed measurement value and the speed credibility of the vehicle according to the vertical force of each wheel and the rotating speed of each wheel; and calculating a target vehicle speed change rate and target change rate credibility of the vehicle based on multiple of the brake master cylinder pressure, the whole vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility, and estimating the longitudinal vehicle speed of the vehicle according to the vehicle speed measurement value, the vehicle speed credibility, the target vehicle speed change rate and the target change rate credibility. Therefore, the problem that the accuracy of vehicle speed estimation is affected due to the fact that an accurate wheel cylinder brake pressure signal cannot be obtained through technical protection in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a method and device for estimating the longitudinal speed of a vehicle, a vehicle and a storage medium. Background Art

[0002] In modern vehicle systems, in order to meet various control requirements, such as ABS (Anti-lock Braking System), VDC (Vehicle Dynamics Control), TCS (Traction Control System), etc., the vehicle control system needs to obtain the longitudinal speed information of the vehicle in real time. However, due to cost control considerations, many vehicles are not equipped with dedicated speed sensor devices. This leads to the need to rely on the speed estimation module to provide the necessary speed information during vehicle design and manufacturing to support the normal operation of the above vehicle control functions.

[0003] In the existing mature vehicle speed estimation algorithms, the real-time wheel cylinder brake pressure signal of each wheel is one of the indispensable input data. These signals are crucial for accurately estimating vehicle speed. However, there are two main problems in obtaining wheel cylinder brake pressure signals:

[0004] The first is the cost limitation. In order to reduce production costs, vehicle manufacturers often do not install expensive wheel cylinder brake pressure sensors. Therefore, in practical applications, the wheel cylinder brake pressure signal is usually an estimated value calculated from other sensor data through a certain algorithm. Although this calculation method can provide the required signal to a certain extent, it will inevitably bring a certain loss of accuracy, especially in complex and changeable driving environments. This accuracy problem may significantly affect the accuracy of vehicle speed estimation.

[0005] The second is the technology protection of suppliers. For the sake of intellectual property and technical confidentiality, brake system suppliers usually do not open detailed wheel cylinder brake pressure estimation algorithms to OEMs, or even if they provide algorithms, they may impose strict restrictions on the specific implementation details of the algorithms. This not only limits OEMs' further optimization and development of vehicle speed estimation technology, but also increases the difficulty for OEMs in developing related control strategies. Summary of the invention

[0006] The present application provides a vehicle longitudinal speed estimation method, device, vehicle and storage medium to solve the problem that the related art cannot obtain accurate wheel cylinder brake pressure signals, resulting in the accuracy of vehicle speed estimation being affected.

[0007] In a first aspect, the present application provides a method for estimating the longitudinal speed of a vehicle, comprising the following steps: obtaining the vehicle's brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle; estimating the vertical force of each wheel of the vehicle based on the acceleration of the whole vehicle, and calculating the vehicle's speed measurement value and speed credibility based on the vertical force of each wheel and the wheel rotation speed; calculating the vehicle's target speed change rate and target change rate credibility based on multiple of the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility, and estimating the vehicle's longitudinal speed based on the speed measurement value and the speed credibility, as well as the target speed change rate and the target change rate credibility.

[0008] Optionally, based on multiple of the brake master cylinder pressure, the vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility, the vehicle's target speed change rate and the target change rate credibility are calculated, including: calculating the vehicle's first speed change rate and the first change rate credibility according to the brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the vertical force of each wheel; calculating the vehicle's second speed change rate and the second change rate credibility according to the vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility; calculating the vehicle's target speed change rate and the target change rate credibility based on the first speed change rate and the first change rate credibility and the second speed change rate and the second change rate credibility.

[0009] Optionally, the first vehicle speed change rate and the first change rate credibility of the vehicle are calculated based on the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel, including: inputting the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel into the longitudinal force observer of the vehicle, and the longitudinal force observer outputs the longitudinal force of each wheel; calculating the first vehicle speed change rate and the first change rate credibility based on the longitudinal force of each wheel.

[0010] Optionally, the calculation formula of the longitudinal force observer is:

[0011]

[0012] Among them, T q is the driving torque; T b is the braking torque; I w is the wheel moment of inertia; is the wheel rotation angular velocity; R e is the effective rolling radius; F rr is the rolling resistance; k1 is the structural parameter in the observer; and are the estimation errors of the angular velocity and longitudinal force of a single wheel, respectively.

[0013] Optionally, a second vehicle speed change rate and a second change rate credibility of the vehicle are calculated based on the vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility, including: obtaining a first target condition and a second target condition of the vehicle, wherein the first target condition is that the vehicle speed credibility is greater than a preset credibility, and the second target condition is that the steering wheel angle of the vehicle is less than a preset angle; if the vehicle satisfies the first target condition and the second target condition at the same time, then obtaining the ramp and zero drift values ​​of the vehicle acceleration and the slow filtering time of the ramp and zero drift values, calculating the second vehicle speed change rate based on the vehicle speed measurement value and the ramp and zero drift values, and calculating the second change rate credibility based on the slow filtering time of the ramp and zero drift values; if the vehicle does not satisfy the first target condition and the second target condition at the same time, then maintaining the vehicle's current second vehicle speed change rate and the second change rate credibility.

[0014] Optionally, based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated, including: identifying whether the current operating condition of the vehicle is the target operating condition, wherein the target operating condition is the operating condition where there is a difference between the brake master cylinder pressure and the actual wheel cylinder pressure; if the current operating condition is the target operating condition, the second vehicle speed change rate is the target vehicle speed change rate and the second change rate credibility is the target change rate credibility; if the current operating condition is not the target operating condition, the target vehicle speed change rate is calculated based on the first vehicle speed change rate and the second vehicle speed change rate, and the target change rate credibility is calculated based on the first change rate credibility and the second change rate credibility.

[0015] Optionally, if the current operating condition is not the target operating condition, the target vehicle speed change rate and the target change rate credibility are calculated as follows:

[0016]

[0017] Among them, dv x_model is the first vehicle speed change rate; dv x_sensor is the second vehicle speed change rate; p_dv x_model is the first change rate credibility; p_dv x_sensor is the second change rate credibility.

[0018] A second aspect of the present application provides a vehicle longitudinal speed estimation device, including: an acquisition module, used to acquire the vehicle's brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle; a first calculation module, used to estimate the vertical force of each wheel of the vehicle according to the acceleration of the whole vehicle, and calculate the vehicle speed measurement value and speed credibility of the vehicle according to the vertical force of each wheel and the wheel speed; a second calculation module, used to calculate the vehicle's target speed change rate and target change rate credibility based on multiple of the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility, and estimate the vehicle's longitudinal speed according to the speed measurement value and the speed credibility, as well as the target speed change rate and the target change rate credibility.

[0019] A third aspect of the present application provides a vehicle, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the vehicle longitudinal speed estimation method of the first aspect.

[0020] A fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the vehicle longitudinal speed estimation method of the first aspect.

[0021] Therefore, this application has at least the following beneficial effects:

[0022] The embodiment of the present application can obtain the vehicle's brake master cylinder pressure, each wheel driving torque, each wheel speed and vehicle acceleration, estimate the vertical force of each wheel of the vehicle, and then calculate the vehicle speed measurement value and speed credibility of the vehicle based on each wheel vertical force and wheel speed. Based on the brake master cylinder pressure, vehicle acceleration, each wheel vertical force, speed measurement value and speed credibility, calculate the vehicle's target speed change rate and target change rate credibility. Finally, the longitudinal speed of the vehicle is estimated based on the speed measurement value and speed credibility, as well as the target speed change rate and target change rate credibility. When the wheel cylinder pressure signal is not available, the same speed estimation accuracy as when the wheel cylinder pressure signal is available is obtained. Therefore, the problem that the accuracy of the vehicle speed estimation is affected due to the inability to obtain an accurate wheel cylinder brake pressure signal in the related art due to technical protection is solved.

[0023] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0025] Figure 1 The overall architecture diagram of vehicle longitudinal speed estimation provided for related technologies;

[0026] Figure 2 A flowchart of a method for estimating the longitudinal speed of a vehicle provided according to an embodiment of the present application;

[0027] Figure 3 A structural diagram of a vehicle longitudinal speed estimation method provided according to an embodiment of the present application;

[0028] Figure 4 A comparison diagram of vehicle speed estimation results provided according to an embodiment of the present application;

[0029] Figure 5 This is an example diagram of a vehicle longitudinal speed estimation device provided according to an embodiment of the present application;

[0030] Figure 6 It is a schematic diagram of the structure of a vehicle provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0032] In existing vehicle systems, due to cost constraints, vehicles will not be equipped with vehicle speed sensor devices, and most vehicle control systems need to refer to real-time vehicle speed information, so a vehicle speed estimation module must be used to estimate the vehicle speed. In existing mature speed estimation algorithms, the real-time wheel cylinder brake pressure signals of each wheel are necessary input signals, but there are two main problems with this signal. On the one hand, due to cost constraints, the wheel cylinder brake pressure signal is not a sensor measurement signal, but an estimated signal calculated by a certain algorithm. Therefore, the wheel cylinder brake pressure signal actually used has certain accuracy problems. On the other hand, from the perspective of technical protection, brake suppliers generally do not provide wheel cylinder brake pressure estimation signals to OEMs, so OEMs cannot use this signal to estimate the vehicle speed status. Figure 1 As shown, it is a solution proposed by the related technology.

[0033] The following describes the vehicle longitudinal speed estimation method, device, vehicle and storage medium of the embodiment of the present application with reference to the accompanying drawings. In view of the problem that the accuracy of vehicle speed estimation is affected by the inability to obtain accurate wheel cylinder brake pressure signals due to technical protection in the related art mentioned in the above background technology, the present application provides a vehicle longitudinal speed estimation method, in which the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle can be obtained, and the vertical force of each wheel of the vehicle can be estimated, and then the vehicle speed measurement value and the vehicle speed credibility of the vehicle are calculated according to the vertical force of each wheel and the wheel speed, and the target speed change rate and the target change rate credibility of the vehicle are calculated based on the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility of the vehicle are calculated, and finally the longitudinal speed of the vehicle is estimated according to the speed measurement value and the speed credibility, and the target speed change rate and the target change rate credibility, and when the wheel cylinder pressure signal is not available, the same vehicle speed estimation accuracy as when the wheel cylinder pressure signal is available is obtained. Thereby, the problem that the accuracy of vehicle speed estimation is affected due to technical protection in the related art that an accurate wheel cylinder brake pressure signal cannot be obtained is solved.

[0034] Specifically, Figure 2 This is a flow chart of a vehicle longitudinal speed estimation method provided in an embodiment of the present application.

[0035] like Figure 2 As shown, the vehicle longitudinal speed estimation method comprises the following steps:

[0036] In step S101 , the master cylinder pressure of the vehicle, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle are obtained.

[0037] Among them, the brake master cylinder pressure can be obtained through the pressure sensor, the driving torque of each wheel can be obtained through the torque sensor, the speed of each wheel can be obtained through the wheel speed sensor, and the acceleration of the whole vehicle can be obtained through the IMU (Inertial Measurement Unit), including acceleration components in three directions, namely longitudinal acceleration, lateral acceleration and vertical acceleration.

[0038] It can be understood that the embodiments of the present application can obtain the vehicle's brake master cylinder pressure, each wheel driving torque, each wheel speed and vehicle acceleration through various sensors and units inside the vehicle.

[0039] In step S102, the vertical force of each wheel of the vehicle is estimated according to the acceleration of the whole vehicle, and the vehicle speed measurement value and the vehicle speed credibility of the vehicle are calculated according to the vertical force of each wheel and the wheel speed.

[0040] Among them, the wheel vertical force can be estimated by using the longitudinal acceleration, lateral acceleration and road slope estimation in the whole vehicle acceleration, the whole vehicle mass and the vehicle center of mass position; the calculation of the vehicle speed measurement value and the vehicle speed credibility requires first obtaining the longitudinal vehicle speed at the corresponding wheel center according to the speed signal of each wheel, and calculating the vehicle speed measurement value, including the longitudinal vehicle speed of each wheel and its corresponding acceleration and acceleration change rate, and finally obtaining the credibility of the longitudinal vehicle speed corresponding to the single wheel speed according to the longitudinal acceleration at the wheel center, the longitudinal acceleration differential and the wheel vertical force, and finally obtaining the vehicle speed measurement value and vehicle speed credibility based on the wheel speed after comprehensive integration of each wheel.

[0041] It can be understood that the embodiments of the present application can use the longitudinal acceleration, lateral acceleration and road slope estimation in the whole vehicle acceleration, the whole vehicle mass and the vehicle center of mass position to estimate the wheel vertical force, and obtain the credibility of the longitudinal vehicle speed corresponding to the single wheel speed based on the speed signal of each wheel, and finally obtain the vehicle speed measurement value and vehicle speed credibility based on the wheel speed after integrating the fusion of each wheel.

[0042] In step S103, based on multiple factors including brake master cylinder pressure, vehicle acceleration, vertical force of each wheel, vehicle speed measurement value and vehicle speed credibility, the target vehicle speed change rate and target change rate credibility of the vehicle are calculated, and the longitudinal speed of the vehicle is estimated based on the vehicle speed measurement value and vehicle speed credibility, as well as the target vehicle speed change rate and target change rate credibility.

[0043] It can be understood that the embodiment of the present application can calculate the target vehicle speed change rate and the target change rate credibility based on multiple parameters such as the brake master cylinder pressure, vehicle acceleration, vertical force of each wheel, vehicle speed measurement value and vehicle speed credibility, and then use the vehicle speed measurement value and vehicle speed credibility, combined with the target vehicle speed change rate and target change rate credibility, to estimate the longitudinal speed of the vehicle. The specific calculation method will be described in detail below and will not be repeated here.

[0044] In an embodiment of the present application, based on multiple of the brake master cylinder pressure, the whole vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated, including: calculating the first vehicle speed change rate and the first change rate credibility of the vehicle according to the brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the vertical force of each wheel; calculating the second vehicle speed change rate and the second change rate credibility of the vehicle according to the whole vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility; calculating the target vehicle speed change rate and the target change rate credibility of the vehicle based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility.

[0045] Among them, the first vehicle speed change rate is a purely theoretical calculation result, and its corresponding first change rate credibility is set to a constant value; the calculation method of the second vehicle speed change rate and the second change rate credibility will be described in detail below and will not be repeated here; based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated and executed through the vehicle speed change rate fusion processing module, which will be described in detail below and will not be repeated here.

[0046] It can be understood that the embodiments of the present application can calculate the first vehicle speed change rate and the first change rate credibility of the vehicle according to the brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the vertical force of each wheel, wherein the first vehicle speed change rate is a purely theoretical calculation result, and its corresponding first change rate credibility is set to a constant value; the second vehicle speed change rate and the second change rate credibility of the vehicle can be calculated according to the vehicle acceleration, the speed measurement value and the speed credibility; based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated through the speed change rate fusion processing module.

[0047] In an embodiment of the present application, a first vehicle speed change rate and a first change rate credibility of the vehicle are calculated based on a brake master cylinder pressure, a driving torque of each wheel, a rotation speed of each wheel and a vertical force of each wheel, including: inputting the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel into a longitudinal force observer of the vehicle, and the longitudinal force observer outputting the longitudinal force of each wheel; and calculating the first vehicle speed change rate and the first change rate credibility based on the longitudinal force of each wheel.

[0048] The longitudinal force observer will be described in detail below and will not be repeated here. The wheel model module is directly used to calculate the first vehicle speed change rate and the first change rate credibility according to the longitudinal force of each wheel.

[0049] It can be understood that the embodiments of the present application can input the brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the vertical force of each wheel into the vehicle's longitudinal force observer, which calculates and outputs the longitudinal force of each wheel, and then uses the wheel model module to calculate the first vehicle speed change rate and the first change rate credibility based on the longitudinal force of each wheel.

[0050] In the embodiment of the present application, the calculation formula of the longitudinal force observer is:

[0051]

[0052] Among them, T q is the driving torque; T b is the braking torque; I w is the wheel moment of inertia; is the wheel rotation angular velocity; R e is the effective rolling radius; F rr is the rolling resistance; k1 is the structural parameter in the observer; and are the estimation errors of the angular velocity and longitudinal force of a single wheel, respectively.

[0053] It can be understood that the longitudinal force observer of the embodiment of the present application can use the driving torque, braking torque, wheel rotational inertia, wheel rotational angular velocity, effective rolling radius, rolling resistance, structural parameters in the observer, and the estimated error of the angular velocity and longitudinal force of a single wheel to calculate the longitudinal force of each wheel through the above formula.

[0054] In an embodiment of the present application, a second vehicle speed change rate and a second change rate credibility of the vehicle are calculated based on the whole vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility, including: obtaining a first target condition and a second target condition of the vehicle, wherein the first target condition is that the vehicle speed credibility is greater than a preset credibility, and the second target condition is that the steering wheel angle of the vehicle is less than a preset angle; if the vehicle satisfies the first target condition and the second target condition at the same time, then the ramp and zero drift value of the whole vehicle acceleration and the slow filtering time of the ramp and zero drift value are obtained, the second vehicle speed change rate is calculated based on the vehicle speed measurement value and the ramp and zero drift value, and the second change rate credibility is calculated based on the slow filtering time of the ramp and zero drift value; if the vehicle does not meet the first target condition and the second target condition at the same time, then the current second vehicle speed change rate and the second change rate credibility of the vehicle are maintained.

[0055] Among them, the preset credibility is set according to the specific situation and is not specifically limited here; the preset turning angle is set according to the specific situation and is not specifically limited here; the zero drift value is the output zero acceleration value obtained when the vehicle is stationary; slow filtering is often used to process sensor output signals, which can be used to eliminate zero drift values ​​and other low-frequency interference, and calculate the second change rate credibility.

[0056] It can be understood that when the embodiment of the present application calculates the second vehicle speed change rate and the second change rate credibility of the vehicle based on the vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility, it is necessary to determine whether the vehicle meets the first target condition and the second target condition, wherein the first target condition is that the vehicle speed credibility is greater than the preset credibility, and the second target condition is that the steering wheel angle of the vehicle is less than the preset angle. When the vehicle satisfies both conditions at the same time, the ramp and zero drift values ​​of the vehicle acceleration and the slow filtering time of the ramp and zero drift values ​​are obtained, and slow filtering processing is performed for the short-term stability of the ramp and zero drift characteristics, and then the second vehicle speed change rate is calculated based on the vehicle speed measurement value and the ramp and zero drift value, and finally the second change rate credibility is calculated; when the vehicle does not meet the first target condition and the second target condition at the same time, the current second vehicle speed change rate and the second change rate credibility of the vehicle are maintained.

[0057] In an embodiment of the present application, based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated, including: identifying whether the current operating condition of the vehicle is the target operating condition, wherein the target operating condition is the operating condition where there is a difference between the brake master cylinder pressure and the actual wheel cylinder pressure; if the current operating condition is the target operating condition, the second vehicle speed change rate is the target vehicle speed change rate and the second change rate credibility is the target change rate credibility; if the current operating condition is not the target operating condition, the target vehicle speed change rate is calculated based on the first vehicle speed change rate and the second vehicle speed change rate, and the target change rate credibility is calculated based on the first change rate credibility and the second change rate credibility.

[0058] Among them, the target operating condition is the operating condition where there is a difference between the brake master cylinder pressure and the actual wheel cylinder pressure, that is, the operating condition where one or more of ABS (Anti-Lock Braking System), TCS (Traction Control System) and VDC (Vehicle Dynamics Control) are activated.

[0059] It can be understood that the embodiment of the present application calculates the target vehicle speed change rate and the target change rate credibility of the vehicle based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility. It is necessary to identify whether the current operating condition of the vehicle is the target operating condition. The target operating condition is the operating condition where there is a difference between the brake master cylinder pressure and the actual wheel cylinder pressure due to ABS / TCS / VDC actuation. When the current operating condition is the target operating condition, the second vehicle speed change rate is the target vehicle speed change rate, and the second change rate credibility is the target change rate credibility. If the current operating condition is not the target operating condition, the target vehicle speed change rate is calculated based on the first vehicle speed change rate and the second vehicle speed change rate, and the target change rate credibility is calculated based on the first change rate credibility and the second change rate credibility. The calculation method will be described in detail below and will not be repeated here.

[0060] In the embodiment of the present application, if the current working condition is not the target working condition, the calculation formulas for the target vehicle speed change rate and the target change rate credibility are as follows:

[0061]

[0062] Among them, dv x_model is the first vehicle speed change rate; dv x_sensor is the second vehicle speed change rate; p_dv x_model is the first change rate credibility; p_dv x_sensor is the second change rate credibility.

[0063] It can be understood that when the current operating condition is not the target operating condition, the embodiment of the present application can use the above formula to calculate the target vehicle speed change rate and the target change rate credibility using the first vehicle speed change rate and the first change rate credibility, the second vehicle speed change rate and the second change rate credibility.

[0064] According to the vehicle longitudinal speed estimation method proposed in the embodiment of the present application, the vehicle's brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle can be obtained, and the vertical force of each wheel of the vehicle can be estimated. Then, the vehicle speed measurement value and the speed credibility of the vehicle are calculated based on the vertical force of each wheel and the wheel speed. Based on the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility, the vehicle's target speed change rate and the target change rate credibility are calculated. Finally, the vehicle's longitudinal speed is estimated based on the speed measurement value and the speed credibility, as well as the target speed change rate and the target change rate credibility. When the wheel cylinder pressure signal is not available, the same speed estimation accuracy as when the wheel cylinder pressure signal is available is obtained.

[0065] The method for estimating the longitudinal speed of a vehicle is further described below by using a specific embodiment. Figure 3 As shown, the specific steps include:

[0066] (1) Estimation of wheel vertical force:

[0067] The tire vertical force estimation is based on the vehicle load transfer model. The input is the longitudinal acceleration, lateral acceleration, estimated road slope, vehicle mass and vehicle center of mass position. The output is the vertical force of the four tires, that is,

[0068] F L1 =F L1st -w x -w y ,

[0069] F L2 =F L2st +w x -w y ,

[0070] F R1 =F R1st -w x +w y ,

[0071] F R2 =F R2st +w x +w y ,

[0072] Among them, F L1st , F L2st , F R1st , F R2stThe static vertical forces of the left front, left rear, right front, and right rear tires, m s is the sprung mass, m u is the unsprung mass of a single wheel, a is the distance from the center of mass to the front axle, b is the distance from the center of mass to the rear axle, l is the wheelbase, h s is the height of the center of mass. The longitudinal and lateral load transfers due to the longitudinal and lateral accelerations are calculated as follows:

[0073]

[0074] (2) Wheel speed processing:

[0075] According to each wheel speed signal, it is converted into the longitudinal vehicle speed wrF at the corresponding wheel center, and the longitudinal acceleration dwrF and the longitudinal acceleration differential ddwrF at each wheel center are obtained according to the signal difference. The credibility of the longitudinal vehicle speed corresponding to the single wheel speed is obtained according to dwrF, ddwrF and the wheel vertical force Fz, that is,

[0076]

[0077] After integrating the information of each wheel, the vehicle speed measurement value v based on the wheel speed is obtained. x_mes Its credibility p_v x_meas

[0078]

[0079] p_v x_meas =sum(Fitness_i) / n

[0080] Where wrF_i, Fitness_i is the speed and credibility corresponding to a single wheel, and n is the total number of wheels.

[0081] (3) Wheel dynamics calculation:

[0082] In the wheel dynamics calculation module, based on the wheel dynamics and observer, the input is the wheel speed and the driving torque signal of the wheel and the braking torque signal converted from the braking pressure. In the present invention, the master cylinder pressure is directly used to replace the wheel cylinder brake pressure, and the output is the longitudinal force of each wheel. The wheel dynamics model is expressed as follows:

[0083]

[0084] Among them, I w is the wheel moment of inertia, ω is the wheel rotation angular velocity, T q is the driving torque, T b is the braking torque, F x is the driving force, F rr is the rolling resistance, re is the effective rolling radius. The constructed longitudinal force observer expression is:

[0085]

[0086] Among them, the structural parameters in the k1 observer are, and are the estimated errors of the angular velocity and longitudinal force of a single wheel, namely:

[0087]

[0088] The estimated angular acceleration of a single wheel is defined as:

[0089]

[0090] Among them, k2 is the structural parameter in the observer.

[0091] (4) Vehicle dynamics module:

[0092] In the vehicle dynamics module, the calculation results of the wheel model module are directly used to derive the vehicle acceleration dv according to the vehicle dynamics. x_model

[0093] dv x_model =sum(Fx) / m

[0094] In DV x_model The calculation results are purely theoretical, and the corresponding credibility p_dv x_model Set to a fixed value;

[0095] (5) IMU longitudinal acceleration processing:

[0096] The acceleration measured by the vehicle-mounted IMU contains the following components, namely

[0097]

[0098] To obtain the effective components of the acceleration signal The IMU acceleration signal is judged and processed as follows to obtain a more reasonable (-slope_x+a x.SensorOff );

[0099] Condition_1: Wheel speed credibility judgment. When the wheel speed credibility is high, the wheel speed reflects the real speed of the vehicle. Equal to based on v x_mes The difference of

[0100] Condition_2: When the steering wheel angle is small, the corresponding vehicle yaw γ and lateral speed v y are both small, so vy γ can be ignored and equal to zero;

[0101] When the above Condition_1 and Condition_2 are satisfied at the same time, Obtain the real-time value slope_x_raw of the sum of the slope and zero drift in the IMU longitudinal acceleration signal; for the short-term stability of the slope and zero drift characteristics, the above calculation results need to be processed by slow filtering to obtain slope_xF; and when Condition_1 and Condition_2 cannot be satisfied at the same time, slope_xF maintains the current value;

[0102] Based on slope_xF, dv based on the IMU longitudinal acceleration signal can be obtained x_sensor

[0103] dv x_sensor＝ a x.Sensor -slope_xF

[0104] And determine dv according to the duration of the slow filter of slope_xF x_sensor The credibility of p_dv x_sensor , that is, the longer the continuous filtering time is, the higher the credibility is.

[0105] (6) Fusion processing of vehicle speed change rate:

[0106] There are two treatment situations depending on whether ABS / TCS / VDC is activated. Under normal working conditions, the two are integrated, namely

[0107]

[0108] When ABS / TCS / VDC is activated, the pressure of the master cylinder is different from the actual pressure of the wheel cylinder, so the dv based on vehicle dynamics is reduced. x_model The calculation result is

[0109] dv x_meas =dv x_sensor

[0110] p_dv x_meas =p_dv x_sensor

[0111] (7) In the Kalman filter model:

[0112] According to the input dv x_meas , p_dv x_meas and v x_mes , p_v x_meas , p_dv x_meas and p_v x_meas Equivalent to dv x_meas and vx_mes The measurement error can be obtained by traditional Kalman filtering. x and v x .

[0113] like Figure 4 As shown, there is a comparison diagram of the new scheme proposed in this embodiment and the original scheme of the related technology using wheel cylinder pressure and only using master cylinder pressure to estimate vehicle speed. The results show that when the wheel cylinder pressure signal is not available, this embodiment achieves the same vehicle speed estimation accuracy as when there is a wheel cylinder pressure signal by equivalently using the brake master cylinder pressure and IMU longitudinal acceleration signal processing.

[0114] Next, the vehicle longitudinal speed estimation device proposed in accordance with the embodiment of the present application is described with reference to the accompanying drawings.

[0115] Figure 5 It is a block diagram of a vehicle longitudinal speed estimation device according to an embodiment of the present application.

[0116] like Figure 5 As shown, the vehicle longitudinal speed estimation device 10 includes: an acquisition module 201 , a first calculation module 202 and a second calculation module 203 .

[0117] Among them, the acquisition module 201 is used to obtain the vehicle's brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the acceleration of the whole vehicle; the first calculation module 202 is used to estimate the vertical force of each wheel of the vehicle according to the acceleration of the whole vehicle, and calculate the vehicle speed measurement value and the speed credibility of the vehicle according to the vertical force of each wheel and the wheel speed; the second calculation module 203 is used to calculate the vehicle's target speed change rate and the target change rate credibility based on the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility, and estimate the vehicle's longitudinal speed according to the speed measurement value and the speed credibility, as well as the target speed change rate and the target change rate credibility.

[0118] In an embodiment of the present application, the second calculation module 203 is further used to calculate the vehicle's first speed change rate and the first change rate credibility based on the brake master cylinder pressure, the driving torque of each wheel, the speed of each wheel and the vertical force of each wheel; calculate the vehicle's second speed change rate and the second change rate credibility based on the vehicle acceleration, the speed measurement value and the speed credibility; calculate the vehicle's target speed change rate and the target change rate credibility based on the first speed change rate and the first change rate credibility and the second speed change rate and the second change rate credibility.

[0119] In an embodiment of the present application, a first vehicle speed change rate and a first change rate credibility of the vehicle are calculated based on a brake master cylinder pressure, a driving torque of each wheel, a rotation speed of each wheel and a vertical force of each wheel, including: inputting the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel into a longitudinal force observer of the vehicle, and the longitudinal force observer outputting the longitudinal force of each wheel; and calculating the first vehicle speed change rate and the first change rate credibility based on the longitudinal force of each wheel.

[0120] In the embodiment of the present application, the calculation formula of the longitudinal force observer is:

[0121]

[0122] Among them, T q is the driving torque; T b is the braking torque; I w is the wheel moment of inertia; is the wheel rotation angular velocity; R e is the effective rolling radius; F rr is the rolling resistance; k1 is the structural parameter in the observer; and are the estimation errors of the angular velocity and longitudinal force of a single wheel, respectively.

[0123] In an embodiment of the present application, a second vehicle speed change rate and a second change rate credibility of the vehicle are calculated based on the whole vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility, including: obtaining a first target condition and a second target condition of the vehicle, wherein the first target condition is that the vehicle speed credibility is greater than a preset credibility, and the second target condition is that the steering wheel angle of the vehicle is less than a preset angle; if the vehicle satisfies the first target condition and the second target condition at the same time, then the ramp and zero drift value of the whole vehicle acceleration and the slow filtering time of the ramp and zero drift value are obtained, the second vehicle speed change rate is calculated based on the vehicle speed measurement value and the ramp and zero drift value, and the second change rate credibility is calculated based on the slow filtering time of the ramp and zero drift value; if the vehicle does not meet the first target condition and the second target condition at the same time, then the current second vehicle speed change rate and the second change rate credibility of the vehicle are maintained.

[0124] In an embodiment of the present application, based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated, including: identifying whether the current operating condition of the vehicle is the target operating condition, wherein the target operating condition is the operating condition where there is a difference between the brake master cylinder pressure and the actual wheel cylinder pressure; if the current operating condition is the target operating condition, the second vehicle speed change rate is the target vehicle speed change rate and the second change rate credibility is the target change rate credibility; if the current operating condition is not the target operating condition, the target vehicle speed change rate is calculated based on the first vehicle speed change rate and the second vehicle speed change rate, and the target change rate credibility is calculated based on the first change rate credibility and the second change rate credibility.

[0125] In the embodiment of the present application, if the current working condition is not the target working condition, the calculation formulas for the target vehicle speed change rate and the target change rate credibility are as follows:

[0126]

[0127] Among them, dv x_model is the first vehicle speed change rate; dv x_sensor is the second vehicle speed change rate; p_dv x_model is the first change rate credibility; p_dv x_sensor is the second change rate credibility.

[0128] It should be noted that the above explanations of the embodiment of the vehicle longitudinal speed estimation method are also applicable to the vehicle longitudinal speed estimation device of this embodiment, and will not be repeated here.

[0129] According to the vehicle longitudinal speed estimation device proposed in the embodiment of the present application, through the coordinated action of the acquisition module, the first calculation module and the second calculation module, the vehicle's brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the acceleration of the whole vehicle can be obtained, and the vertical force of each wheel of the vehicle can be estimated. Then, the vehicle speed measurement value and the speed credibility of the vehicle are calculated according to the vertical force of each wheel and the wheel speed. Based on the brake master cylinder pressure, the acceleration of the whole vehicle, the vertical force of each wheel, the speed measurement value and the speed credibility, the target speed change rate and the target change rate credibility of the vehicle are calculated. Finally, the longitudinal speed of the vehicle is estimated based on the speed measurement value and the speed credibility, as well as the target speed change rate and the target change rate credibility. When the wheel cylinder pressure signal is not available, the same speed estimation accuracy as when the wheel cylinder pressure signal is available is obtained.

[0130] Figure 6 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application. The vehicle may include:

[0131] A memory 301 , a processor 302 , and a computer program stored in the memory 301 and executable on the processor 302 .

[0132] When the processor 302 executes the program, the vehicle longitudinal speed estimation method provided in the above embodiment is implemented.

[0133] Furthermore, the vehicle also includes:

[0134] The communication interface 303 is used for communication between the memory 301 and the processor 302 .

[0135] The memory 301 is used to store computer programs that can be run on the processor 302 .

[0136] The memory 301 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0137] If the memory 301, the processor 302 and the communication interface 303 are implemented independently, the communication interface 303, the memory 301 and the processor 302 can be connected to each other through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0138] Optionally, in a specific implementation, if the memory 301, the processor 302 and the communication interface 303 are integrated on a chip, the memory 301, the processor 302 and the communication interface 303 can communicate with each other through an internal interface.

[0139] The processor 302 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0140] The embodiment of the present application further provides a computer-readable storage medium on which a computer program is stored. The program is executed by a processor to implement the above-mentioned vehicle longitudinal speed estimation method.

[0141] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0142] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0143] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0144] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0145] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

Claims

1. A method for estimating a vehicle longitudinal speed, characterized in that: The following steps are involved: Obtain the vehicle's brake master cylinder pressure, each wheel driving torque, each wheel speed and vehicle acceleration; estimating the vertical force of each wheel of the vehicle according to the whole vehicle acceleration, and calculating the vehicle speed measurement value and vehicle speed credibility of the vehicle according to the vertical force of each wheel and the wheel speed; Based on multiple of the brake master cylinder pressure, the vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility, the target vehicle speed change rate and the target change rate credibility of the vehicle are calculated, and the longitudinal speed of the vehicle is estimated based on the vehicle speed measurement value and the vehicle speed credibility, and the target vehicle speed change rate and the target change rate credibility.

2. The method for estimating the longitudinal speed of a vehicle according to claim 1, characterized in that: The calculating the target vehicle speed change rate and the target change rate credibility of the vehicle based on multiple of the brake master cylinder pressure, the vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility includes: Calculating a first vehicle speed change rate and a first change rate credibility of the vehicle according to the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel; Calculating a second vehicle speed change rate and a second change rate credibility of the vehicle according to the vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility; Based on the first vehicle speed change rate and the first change rate reliability and the second vehicle speed change rate and the second change rate reliability, a target vehicle speed change rate and a target change rate reliability of the vehicle are calculated.

3. The method for estimating the longitudinal speed of a vehicle according to claim 2, characterized in that: The calculating the first vehicle speed change rate and the first change rate credibility of the vehicle according to the brake master cylinder pressure, the driving torque of each wheel, the rotation speed of each wheel and the vertical force of each wheel includes: Inputting the master cylinder pressure, the wheel driving torque, the wheel speed and the wheel vertical force into the longitudinal force observer of the vehicle, the longitudinal force observer outputs the longitudinal force of each wheel; The first vehicle speed change rate and the first change rate credibility are calculated according to the longitudinal forces of each wheel.

4. The method for estimating the longitudinal speed of a vehicle according to claim 3, characterized in that: The calculation formula of the longitudinal force observer is: Among them, T q is the driving torque; T b is the braking torque; I w is the wheel moment of inertia; is the wheel rotation angular velocity; R e is the effective rolling radius; F rr is the rolling resistance; k1 is the structural parameter in the observer; and are the estimation errors of the angular velocity and longitudinal force of a single wheel, respectively.

5. The method for estimating the longitudinal speed of a vehicle according to claim 2, characterized in that: The calculating the second vehicle speed change rate and the second change rate credibility of the vehicle according to the vehicle acceleration, the vehicle speed measurement value and the vehicle speed credibility includes: Acquire a first target condition and a second target condition of the vehicle, wherein the first target condition is that the vehicle speed credibility is greater than a preset credibility, and the second target condition is that the steering wheel angle of the vehicle is less than a preset angle; If the vehicle satisfies both the first target condition and the second target condition, the ramp and zero drift value of the whole vehicle acceleration and the slow filtering time length of the ramp and zero drift value are obtained, the second vehicle speed change rate is calculated according to the vehicle speed measurement value and the ramp and zero drift value, and the credibility of the second change rate is calculated according to the slow filtering time length of the ramp and zero drift value; If the vehicle does not satisfy the first target condition and the second target condition at the same time, the current second vehicle speed change rate and the second change rate credibility of the vehicle are maintained.

6. The method for estimating the longitudinal speed of a vehicle according to claim 2, characterized in that: The calculating the target vehicle speed change rate and the target change rate credibility of the vehicle based on the first vehicle speed change rate and the first change rate credibility and the second vehicle speed change rate and the second change rate credibility includes: Identifying whether the current operating condition of the vehicle is a target operating condition, wherein the target operating condition is a condition in which there is a difference between the master brake cylinder pressure and the actual wheel cylinder pressure; If the current operating condition is the target operating condition, the second vehicle speed change rate is the target vehicle speed change rate and the second change rate credibility is the target change rate credibility; If the current operating condition is not the target operating condition, the target vehicle speed change rate is calculated according to the first vehicle speed change rate and the second vehicle speed change rate, and the target change rate credibility is calculated according to the first change rate credibility and the second change rate credibility.

7. The method for estimating the longitudinal speed of a vehicle according to claim 6, characterized in that: If the current operating condition is not the target operating condition, the target vehicle speed change rate and the target change rate credibility are calculated as follows: Among them, dv x_model is the first vehicle speed change rate; dv x_sensor is the second vehicle speed change rate; p_dv x_model is the first change rate credibility; p_dv x_sensor is the second change rate credibility.

8. A vehicle longitudinal speed estimation device, characterized in that: include: An acquisition module is used to acquire the vehicle's brake master cylinder pressure, each wheel driving torque, each wheel speed and vehicle acceleration; a first calculation module, configured to estimate the vertical force of each wheel of the vehicle according to the whole vehicle acceleration, and calculate the vehicle speed measurement value and the vehicle speed credibility of the vehicle according to the vertical force of each wheel and the wheel speed; The second calculation module is used to calculate the target vehicle speed change rate and the target change rate credibility of the vehicle based on multiple of the brake master cylinder pressure, the vehicle acceleration, the vertical force of each wheel, the vehicle speed measurement value and the vehicle speed credibility, and estimate the longitudinal speed of the vehicle according to the vehicle speed measurement value and the vehicle speed credibility, and the target vehicle speed change rate and the target change rate credibility.

9. A vehicle, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the vehicle longitudinal speed estimation method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the vehicle longitudinal speed estimation method as described in any one of claims 1 to 7.

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