Vehicle pitch angle determination method, device, controller, vehicle and storage medium

Abstract

The application provides a vehicle pitch angle determination method, device, controller, vehicle and storage medium. The method comprises the following steps: acquiring a front wheel measured wheel speed, a rear wheel measured wheel speed, a front wheel torque, a rear wheel torque and a vehicle displacement of a vehicle; determining a front wheel driving wheel speed and a rear wheel driving wheel speed respectively according to the front wheel torque and the rear wheel torque; determining a front wheel wheel speed difference value according to the front wheel measured wheel speed and the front wheel driving wheel speed; determining a rear wheel wheel speed difference value according to the rear wheel measured wheel speed and the rear wheel driving wheel speed; and determining an estimated pitch angle according to the front wheel wheel speed difference value, the rear wheel wheel speed difference value and the vehicle displacement. According to the method, only the vehicle wheel speed, the torque and the displacement are needed to know, so that the effect of estimating the pitch angle is achieved without using a pitch angle test sensor. Moreover, the influence of the torque, the load fluctuation and the suspension disturbance fluctuation is introduced, so that the estimation accuracy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicles, in particular to a method and device for determining a pitch angle of a vehicle, a controller, a vehicle and a storage medium. BACKGROUND

[0002] During driving, due to uneven road surface, acceleration, deceleration and other reasons, the vehicle will produce pitch motion, i.e. the change of the inclination angle in the front-rear direction of the vehicle. The pitch angle of the vehicle not only affects the driving stability and ride comfort of the vehicle, but also directly relates to the handling performance and safety of the vehicle. Therefore, it is of great significance to accurately calculate and monitor the pitch angle of the vehicle.

[0003] At present, the pitch angle is mainly measured by using an inertial measurement unit (IMU) to measure the pitch angle, which undoubtedly increases the hardware cost. To solve this problem, one solution is to obtain the pitch angle of the vehicle according to the deviation between the actual acceleration of the vehicle and the measured longitudinal acceleration, which has the problem of low precision.

[0004] Therefore, how to accurately estimate the pitch angle without using a pitch angle test sensor is a problem to be solved. SUMMARY

[0005] The present application provides a method and device for determining a pitch angle of a vehicle, a controller, a vehicle and a storage medium, so as to estimate the pitch angle without using a pitch angle test sensor.

[0006] In a first aspect, the present application provides a method for determining a pitch angle of a vehicle, the method comprising:

[0007] obtaining a front wheel measured wheel speed, a rear wheel measured wheel speed, a front wheel torque, a rear wheel torque and a vehicle displacement of the vehicle;

[0008] determining a front wheel driving wheel speed and a rear wheel driving wheel speed according to the front wheel torque and the rear wheel torque, respectively;

[0009] determining a front wheel speed difference value according to the front wheel measured wheel speed and the front wheel driving wheel speed;

[0010] determining a rear wheel speed difference value according to the rear wheel measured wheel speed and the rear wheel driving wheel speed;

[0011] determining an estimated pitch angle according to the front wheel speed difference value, the rear wheel speed difference value and the vehicle displacement.

[0012] In a possible implementation, the determining of the estimated pitch angle according to the front wheel speed difference value, the rear wheel speed difference value and the vehicle displacement comprises:

[0013] According to the front wheel speed difference value, the rear wheel speed difference value and the vehicle displacement, a predicted pitch angle is determined by a preset Kalman filter model, the Kalman filter model being used to represent a mapping relationship between the front wheel speed difference value, the rear wheel speed difference value, the vehicle displacement and the predicted pitch angle.

[0014] In a possible implementation, the vehicle displacement includes a front wheel displacement, a rear wheel displacement, a road displacement and a vehicle bounce displacement.

[0015] In a possible implementation, the Kalman filter model is a model constructed in advance according to a front wheel speed difference value, a rear wheel speed difference value, a front wheel displacement, a derivative of the front wheel displacement with respect to time, a rear wheel displacement, a derivative of the rear wheel displacement with respect to time, a vehicle bounce displacement, a pitch angle and a derivative of the pitch angle with respect to time.

[0016] In a possible implementation, the determining of the front wheel driving speed and the rear wheel driving speed according to the front wheel torque and the rear wheel torque respectively includes:

[0017] The front wheel driving speed is determined according to the front wheel torque and the rear wheel torque by a first formula, the first formula being used to represent a mapping relationship between a front wheel torque speed and the front wheel torque, the rear wheel torque, a front wheel radius, a rear wheel radius, a vehicle mass, a front wheel inertia torque and a rear wheel inertia torque;

[0018] The front wheel driving speed is determined according to the front wheel torque and the rear wheel torque by a second formula, the second formula being used to represent a mapping relationship between a rear wheel torque speed and the front wheel torque, the rear wheel torque, the front wheel radius, the rear wheel radius, the vehicle mass, the front wheel inertia torque and the rear wheel inertia torque.

[0019] In a possible implementation, the determining of the front wheel speed difference value according to the front wheel measured speed and the front wheel driving speed includes:

[0020] The front wheel speed difference value is obtained by subtracting the front wheel driving speed from the front wheel measured speed;

[0021] Correspondingly, the determining of the rear wheel speed difference value according to the rear wheel measured speed and the rear wheel driving speed includes:

[0022] The rear wheel speed difference value is obtained by subtracting the rear wheel driving speed from the rear wheel measured speed.

[0023] In a possible implementation, the method further includes:

[0024] The front wheel torque and the rear wheel torque of the vehicle are controlled according to the predicted pitch angle.

[0025] Secondly, this application also provides a device for determining the pitch angle of a vehicle, the device comprising:

[0026] The acquisition module is used to acquire the measured wheel speed of the front wheels, the measured wheel speed of the rear wheels, the torque of the front wheels, the torque of the rear wheels, and the vehicle displacement.

[0027] The first determining module is used to determine the front wheel drive speed and the rear wheel drive speed based on the front wheel torque and the rear wheel torque, respectively.

[0028] The second determining module is used to determine the front wheel speed difference based on the measured front wheel speed and the front wheel drive wheel speed.

[0029] The third determining module is used to determine the rear wheel speed difference based on the measured rear wheel speed and the rear wheel drive speed.

[0030] The fourth determining module is used to determine the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement.

[0031] In one possible implementation, the fourth determining module is specifically used for:

[0032] Based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement, a predicted pitch angle is determined using a preset Kalman filter model. The Kalman filter model represents the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement, and the predicted pitch angle.

[0033] In one possible implementation, the vehicle displacement includes front wheel displacement, rear wheel displacement, road displacement, and vehicle bounce displacement.

[0034] In one possible implementation, the Kalman filter model is a model pre-constructed based on the front wheel speed difference, the rear wheel speed difference, the front wheel displacement, the derivative of the front wheel displacement with time, the rear wheel displacement, the derivative of the rear wheel displacement with time, the vehicle bounce displacement, the pitch angle, and the derivative of the pitch angle with time.

[0035] In one possible implementation, the first determining module is specifically used for:

[0036] Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a first formula. The first formula is used to represent the mapping relationship between the front wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque.

[0037] Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a second formula. The second formula is used to represent the mapping relationship between the rear wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque.

[0038] In one possible implementation, the second determining module is specifically used for:

[0039] The front wheel speed difference is obtained by subtracting the front wheel drive wheel speed from the measured front wheel speed.

[0040] Accordingly, the third determining module is specifically used for:

[0041] The difference in rear wheel speed is obtained by subtracting the measured rear wheel speed from the rear wheel drive speed.

[0042] Optionally, the device further includes a control module, which is specifically used for:

[0043] The estimated pitch angle is used to control the front and rear wheel torques of the vehicle.

[0044] Thirdly, this application also provides a controller, including: a memory and a processor;

[0045] The memory stores computer-executed instructions;

[0046] The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any of the first aspects.

[0047] Fourthly, this application also provides a vehicle including a controller for performing the method as described in any of the first aspects.

[0048] Fifthly, this application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any of the first aspects.

[0049] Sixthly, this application also provides a computer program product, including a computer program that, when executed by a processor, is used to implement the method as described in any of the first aspects.

[0050] This application provides a method, apparatus, controller, vehicle, and storage medium for determining vehicle pitch angle. The method includes: acquiring the measured wheel speeds of the front and rear wheels, the front wheel torque, the rear wheel torque, and the vehicle displacement; determining the front-wheel drive wheel speed and the rear-wheel drive wheel speed based on the front and rear wheel torques, respectively; determining the front wheel speed difference based on the measured front wheel speed and the front-wheel drive wheel speed; determining the rear wheel speed difference based on the measured rear wheel speed and the rear-wheel drive wheel speed; and determining the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement. This method only requires knowledge of the vehicle's wheel speeds, torque, and displacement, achieving the effect of estimating the pitch angle without using a pitch angle test sensor. Furthermore, this method comprehensively considers the influence of torque, load fluctuations, and suspension deflection fluctuations, improving the estimation accuracy. Attached Figure Description

[0051] 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.

[0052] Figure 1 A schematic diagram illustrating a scenario for determining a vehicle pitch angle, as provided in this application;

[0053] Figure 2 A flowchart illustrating an embodiment of the method for determining the vehicle pitch angle provided in this application;

[0054] Figure 3 A diagram illustrating the change in wheel speed with vehicle pitch. Figure 1 ;

[0055] Figure 4 A diagram illustrating the changes in wheel movement as the vehicle body pitches. Figure 2 ;

[0056] Figure 5 This diagram illustrates the change in wheel speed with suspension deflection. Figure 1 ;

[0057] Figure 6 Diagram showing the change in wheel motion caused by suspension deflection Figure 2 ;

[0058] Figure 7 This is a schematic diagram illustrating the variation of wheel speed with load.

[0059] Figure 8 The effective rolling radius and load radius of the tire vary with the fluctuation of wheel load.

[0060] Figure 9 This is a schematic diagram of the driving torque of the complete vehicle model;

[0061] Figure 10 This is a schematic diagram of the pitch angle estimation algorithm;

[0062] Figure 11 A schematic diagram showing the estimated and measured pitch angle values;

[0063] Figure 12 A schematic diagram of the structure of an embodiment of the vehicle pitch angle determination device provided in this application;

[0064] Figure 13 A schematic diagram of the structure of the electronic device provided in this application.

[0065] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0066] Exemplary 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 denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0067] First, let me explain the terms used in this application:

[0068] Vehicle pitch angle: refers to the pitch motion that a vehicle will produce during driving due to uneven road surfaces, acceleration, deceleration, etc., that is, the change in the tilt angle of the vehicle in the front-to-back direction.

[0069] A vehicle's pitch angle not only affects its ride stability and comfort, but also directly relates to its handling performance and safety. Therefore, accurately calculating and monitoring a vehicle's pitch angle is of great significance.

[0070] Figure 1 This application provides a schematic diagram of a scenario for determining a vehicle pitch angle, such as... Figure 1 As shown, during vehicle operation, deceleration causes the rear of the vehicle to deviate more than the front, resulting in a change in the vehicle's tilt angle. In other scenarios, uneven road surfaces may also cause the vehicle to tilt at both ends.

[0071] As can be seen from the above scenarios, current technologies primarily measure vehicle pitch angle by installing an Inertial Measurement Unit (IMU) on the vehicle body, but this equipment is expensive. To address this issue, some solutions estimate the vehicle's pitch angle by measuring lateral acceleration, longitudinal acceleration, and yaw rate. However, this method still requires an acceleration measurement unit and does not consider pitch changes caused by variations in vehicle dynamics, thus leading to low estimation accuracy.

[0072] In view of this, during their research in this field, the inventors, starting from the principles of vehicle kinematics and considering the changes in wheel speed with vehicle pitch, suspension deflection, wheel load fluctuations, and drive torque, constructed a calculation model that can predict pitch angle, improving the accuracy of pitch angle prediction and saving the cost of sensors for measuring pitch angle.

[0073] The pitch angle determination method provided in this application can be used not only for four-wheel drive vehicles, but also for front-wheel drive vehicles and rear-wheel drive vehicles. There are no restrictions on the vehicle's energy type; it can be a gasoline vehicle, a new energy vehicle, or a hybrid vehicle.

[0074] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0075] Figure 2 The flowchart of Embodiment 1 of the method for determining the vehicle pitch angle provided in this application is as follows: Figure 2 As shown, the method includes:

[0076] S101. Obtain the measured wheel speed of the front wheels, the measured wheel speed of the rear wheels, the torque of the front wheels, the torque of the rear wheels, and the vehicle displacement.

[0077] In this step, the measured wheel speeds of the front and rear wheels of the vehicle are obtained using wheel speed sensors. The wheel speed sensors are configured and operate on the following principle: they consist of two parts: a rotating part mounted on the wheel hub or brake drum, and a fixed part mounted on the steering knuckle or brake bracket. Because the rotating and fixed parts are separate, the wheel speed varies with vehicle pitch, suspension deflection, and wheel load fluctuations. Therefore, changes in wheel speed can be used to estimate the vehicle's attitude state, such as vehicle pitch, suspension deflection, and wheel load fluctuations.

[0078] Front wheel torque and rear wheel torque can be obtained by measuring wheel torque sensors or directly from the electronic control unit.

[0079] Vehicle displacement includes front wheel displacement, rear wheel displacement, road displacement, and vehicle bounce displacement. These can be measured using pre-set displacement sensors, determining the displacement value of each position relative to its respective reference position at the measurement moment. Specifically, front wheel bounce displacement represents the vertical displacement of the front vehicle body relative to a front vehicle reference position, rear wheel bounce displacement represents the vertical displacement of the rear vehicle body relative to a rear vehicle reference position, front wheel displacement represents the vertical displacement of the front wheel center relative to a front wheel center reference position, and rear wheel displacement represents the vertical displacement of the rear wheel center relative to a rear wheel center reference position. Road displacement includes front wheel road input displacement (i.e., the change in road surface height at the front wheel contact point) and rear wheel road input displacement (the change in road surface height at the rear wheel contact point). The road input displacement of the front and rear wheel contact points can be acquired using high-precision ground sensors or laser scanning systems. For example, vehicles can be equipped with ground sensors to monitor changes in road surface height, thereby calculating the road displacement of the wheel contact points. Vehicle bounce displacement can be monitored using dedicated vehicle vibration sensors or suspension system sensors, enabling real-time monitoring of vehicle body vibration and bounce displacement. It should be noted that if it is a front-wheel drive vehicle, the torque of the rear wheels is 0, and if it is a rear-wheel drive vehicle, the torque of the front wheels is 0.

[0080] S102. Determine the front-wheel drive speed and the rear-wheel drive speed based on the front wheel torque and the rear wheel torque, respectively.

[0081] In this step, during actual vehicle operation, pitch changes occur due to road conditions or user acceleration / deceleration, which will be reflected in the vehicle data as changes in the front-wheel drive wheel speeds and rear-wheel drive wheel speeds. Therefore, when predicting the vehicle's pitch angle, the front-wheel drive wheel speeds and rear-wheel drive wheel speeds must first be determined. It should be noted that the drive wheel speeds determined in this step are theoretical values ​​calculated based on the torque applied to the wheels, not actual measured values.

[0082] The calculation of front-wheel drive and rear-wheel drive wheel speeds can be determined using a pre-set first formula and a second formula. The first formula represents the mapping relationship between front-wheel torque wheel speed and front-wheel torque, rear-wheel torque, front-wheel radius, rear-wheel radius, vehicle mass, front-wheel inertial torque, and rear-wheel inertial torque. The second formula represents the mapping relationship between rear-wheel torque wheel speed and front-wheel torque, rear-wheel torque, front-wheel radius, rear-wheel radius, vehicle mass, front-wheel inertial torque, and rear-wheel inertial torque.

[0083] The first and second formulas mentioned above are derived beforehand based on the vehicle's kinematic equations and are used to calculate the front-wheel drive wheel speed and rear-wheel drive wheel speed. The detailed derivation process will be introduced later. The first and second formulas can be expressed in the following forms:

[0084] First formula:

[0085] Second formula:

[0086] Among them, w torqf w represents the speed of the front-wheel drive wheels. torqr T represents the rear-wheel drive wheel speed. f T represents the torque of the front wheels. r Represents the rear wheel torque, r f The radius of the front wheel is represented by r. r Indicates the rear wheel radius, I wf I represents the inertial torque of the front wheels. wr This represents the inertial torque of the rear wheels.

[0087] In some embodiments, r f It is the actual measured front wheel radius, i.e., the distance from the center of the front wheel to the ground; r r This is the actual measured rear wheel radius, representing the distance from the center of the rear wheel to the ground. wf The inertial torque of the front wheel is a fixed value, I wr The inertial torque of the rear wheel is a fixed value.

[0088] By integrating the front wheel torque and rear wheel torque collected in real time over time, the front wheel drive speed and rear wheel drive speed are obtained respectively.

[0089] S103. Determine the front wheel speed difference based on the measured front wheel speed and the front wheel drive speed.

[0090] The front wheel speed difference is obtained by subtracting the front drive wheel speed from the measured front wheel speed.

[0091] S104. Determine the rear wheel speed difference based on the measured rear wheel speed and the rear wheel drive speed.

[0092] The difference in rear wheel speed is obtained by subtracting the rear drive wheel speed from the measured rear wheel speed.

[0093] S105. Determine the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement.

[0094] After obtaining the front wheel speed difference and rear wheel speed difference, the vehicle's pitch angle can be predicted based on the acquired vehicle displacement. The principle is as follows:

[0095] During vehicle operation, wheel speed is affected by vehicle pitch, suspension deflection, wheel load fluctuations, and changes in drive torque. Therefore, changes in wheel speed can be used to estimate the vehicle's attitude state, such as vehicle pitch, suspension deflection, and wheel load fluctuations. The total wheel speed signal (i.e., the measured wheel speed) can be written as:

[0096] ω total =ωbody +ω sus +ω tire +ω toq

[0097] Where, ω body ω sus ω tire ω toq These are the changes in wheel speed due to vehicle pitch, suspension deflection, wheel load fluctuations, and drive torque. ω total This represents the total wheel speed, i.e., the measured wheel speed.

[0098] (1) For ω body Its expression and reasoning process are as follows:

[0099] Figure 3 A diagram illustrating the change in wheel speed with vehicle pitch. Figure 1 , Figure 3 As shown, h is the center of gravity O of the vehicle body. b The height from the ground, r is the effective rolling radius of the wheel, L p From O b The length to the center O of the wheel, It is L p The angle between the horizontal and the horizontal directions, θ p It's the vehicle's pitch angle.

[0100] Figure 4 A diagram illustrating the changes in wheel movement as the vehicle body pitches. Figure 2 , due to θ p The value is small, pitch angle is related to L p The impact of the change is relatively small, therefore L p Changes:

[0101] L p1 ≈L p

[0102] In the above formula, L p1 When generating a pitch angle, it starts from O. b Length to the wheel center O. Wheel horizontal motion value:

[0103]

[0104] In the formula, θ w It is the wheel roll angle. (By...) Figure 4 It can be known that:

[0105]

[0106] In the wheel speed sensor, the fixed part changes with the vehicle's pitch angle θ. p Rotation, the angle of the rotated part is equal to θ wTherefore, the change in wheel speed caused by vehicle pitch can be written as:

[0107]

[0108] in, and They are θ p and θ w The derivative of ω. The above formula is ω. body The expression.

[0109] (2) For ω sus Its expression and reasoning process are as follows:

[0110] Figure 5 This diagram illustrates the change in wheel speed with suspension deflection. Figure 1 , Figure 5 As shown, the wheel speed varies with the suspension deflection z. s And change, O s It is the instantaneous rotation center of the suspension, O g It is the contact point between the wheel and the ground, L s From O s The length L from the center O of the wheel is from O s The horizontal length θ0 to O is OO s The angle between the horizontal and the horizontal direction, θ is O g O s The angle between the ground and the z s It refers to suspension deflection.

[0111] Figure 6 Diagram showing the change in wheel motion caused by suspension deflection Figure 2 The horizontal motion value of the wheel is:

[0112] rθ t =z s tanθ0

[0113] Where θ t It is the wheel roll angle. Because the fixed part of the wheel speed sensor surrounds O... s Rotation θ r ,therefore:

[0114] L s1 ≈L s

[0115] Among them, L s1 From O s The length to O, around the fixed part O s Rotation value:

[0116]

[0117] Where, θr It is a fixed part around O s The rotation angle. (By) Figure 5 , Figure 6 It can be seen that,

[0118]

[0119] Therefore, the change in wheel speed caused by suspension deflection can be written as:

[0120]

[0121] in, and They are θ t θ r and z s The derivative. According to Figure 6 ,

[0122] L tanθ=L tanθ0+r

[0123] Therefore, the wheel speed change caused by suspension deflection can be simplified as follows:

[0124]

[0125] (3) For ω tire Its expression and reasoning process are as follows:

[0126] Figure 7 This is a schematic diagram illustrating the change in wheel speed with load, as shown below. Figure 7 As shown, the wheel is under normal load F z Under the action of r, it rolls at a speed of V, where r free That is, the free radius r in the figure that has not undergone deformation. load is the loading radius, i.e., the radius after full load, and r is the effective rolling radius after a certain load. The rolling speed ω is:

[0127]

[0128] The differential of the rolling speed ω can be written as:

[0129]

[0130] In the formula, δr is the difference in r, and the measured value of δr varies with the wheel load δF. z The effective rolling radius can be calculated using the normal load increment, the slope and curvature of the road longitudinal profile. However, due to the complexity of actual road longitudinal profiles, it is difficult to describe δr and δF with simple functions. z The relationship. For example... Figure 7 As shown, the difference δr between the tire loading radii load With δF zIt is directly proportional, meaning that the greater the change in load, the greater the change in tire loading radius. Therefore, it can be written as:

[0131]

[0132] In the formula, k t It refers to the radial stiffness of the tire, δr load With δF z The measurement relationship between them is as follows Figure 8 As shown, Figure 8 This represents the variation of the tire's effective rolling radius and load radius with wheel load fluctuations. In practical tire model applications, gradient and F z Place The gradient is approximately proportional to:

[0133]

[0134] In the formula, η(F) z () is a proportional value. Because It is a constant within the range of wheel load fluctuations, although η(F) z The value of ) varies with F z The wheel speed changes with the load on the wheel, but a constant can be used. Therefore, the change in wheel speed caused by the wheel load can be written as:

[0135]

[0136] In the formula, r(F) z ) is the normal load F z The effective rolling radius is as follows.

[0137] (4) For ω toq Its expression and reasoning process are as follows:

[0138] Figure 9 This is a schematic diagram of the driving torque of the complete vehicle model. The torques at the front and rear axle ends are T respectively. f and T r V and V b These are the vehicle body speed and wheel speed, F. xf and F xr These are the front and rear axle drive forces, M b M wf and M wr It refers to the mass of the car body, front wheels, and rear wheels, I wf and I wr These are the wheel inertial torques. The vehicle's equation of motion can be written as:

[0139]

[0140] In the formula, m motol It is the total mass of the vehicle.

[0141] m motol =M b +2M wf +2M wr

[0142] Ignoring tire slippage speed and assuming the vehicle body and wheel speeds are equal, then the front-wheel drive wheel speed w torqf and rear-wheel drive wheel speed w torqr It can be written as:

[0143]

[0144] In summary, in actual vehicle testing, ω body ω sus ω tire and ω toq The value of ω can be calculated using vehicle design parameters and measured state variables to obtain the total vehicle wheel speed. Therefore, the total wheel speed ω is obtained through wheel speed sensors. total Then, the change in pitch angle with respect to wheel speed can be calculated in reverse, thus determining the pitch angle itself. It should be noted that for front-wheel drive or rear-wheel drive vehicles, the pitch angle can be calculated using only the speed of the wheels with driving force.

[0145] In one solution method, ω is obtained by using the formulas described above. body Calculating the pitch angle would require real-time measurement of changes in deflection, wheel load, and loading radius, resulting in an excessive number of state variables to measure. Therefore, a Kalman filter model is used to estimate vehicle attitude state variables, encompassing pitch angle, wheel load fluctuations, and suspension deflection changes. This model maps the front wheel speed difference, rear wheel speed difference, vehicle displacement, and the estimated pitch angle. The matrix parameters in the Kalman filter model are pre-determined using the mapping relationship between the actually measured pitch angle and wheel speed differences, which will be explained in detail below.

[0146] In the formula subscripts of this application, f represents the front wheel, r represents the rear wheel, a dot above the letter indicates the first derivative of the physical quantity with respect to time, and two dots above the letter indicate the second derivative of the physical quantity with respect to time. bf This indicates the front wheel bounce displacement (i.e., the vertical displacement of the front of the vehicle body), z br Represents the rear wheel bounce displacement (vertical displacement of the rear vehicle body), z wf This indicates the front wheel displacement (i.e., the vertical displacement of the front wheel center), z wr Represents the rear wheel displacement (i.e., the vertical displacement of the rear wheel center), z 0f This represents the front wheel road input displacement (i.e., the change in road surface height at the front wheel contact point) and z. 0rRear wheel road input displacement (change in road surface height at the rear wheel contact point), (where, in all formulas, subscript f represents the front wheel and subscript r represents the rear wheel), θ p Vehicle center of gravity O b The pitch angle at that point, k sf It is the front wheel suspension stiffness, k sr Rear suspension stiffness, c sf It is the front wheel damping coefficient, c sr It is the rear wheel damping coefficient, k tf It is the stiffness of the front tires and k tr It refers to the rear tire stiffness, in meters (m). b and I p These are vehicle mass and pitch inertia, m wf It is the mass of the front wheel, m wr It refers to the mass of the rear wheels. The overall vehicle bounce displacement z can be determined based on the front and rear wheel bounce displacements. b .

[0147] The vehicle motion equations input from the road are as follows:

[0148]

[0149] z sf =z wf -z bf

[0150] z sr =z wr -z br

[0151] In the formula, L f and L r From O b To the front and rear center of gravity O bf and O br The length of the wheel load fluctuation δF. zf and δF zr It can be written as:

[0152] δF zf =k tf (z 0f -z wf )

[0153] δF zr =k tr (z 0r -z wr )

[0154] Substituting the above equation into w torqr and w torqf The calculation formula yields:

[0155]

[0156] y1=C1x1+H1y2

[0157] in,

[0158] y1=[ω meaf -ω torqf ω mear -ω torqr ] T

[0159]

[0160] ω meaf This is the measured wheel speed of the front wheel, ω. mear These are the measured wheel speeds of the rear wheels. A1 is an 8×8 matrix, G1 is an 8×2 matrix, C1 is a 2×8 matrix, and H1 is a 2×1 matrix.

[0161] The road input y2 is:

[0162]

[0163] y2=C2x2+D2w

[0164] In one configuration, A2 = [0 0; 0 0], B2 = [1 0; 0 1], C2 = B2, D2 = A2, x2 = [z 0f z 0r ] T y2=x2,

[0165] Therefore, the extended equation can be obtained as follows:

[0166]

[0167] y = Cx + Du + Hw

[0168] Where, x = [x1 x2] T u = [0 0] T ,y=y1, C=[C1 H1C2],D=D1,H=[H1D2]

[0169] Based on the extended equation, and using the actual measured front wheel displacement, the derivative of front wheel displacement with time, rear wheel displacement, the derivative of rear wheel displacement with time, vehicle bounce displacement, pitch angle, and the derivative of pitch angle with time in x1, as well as the front wheel speed difference and rear wheel speed difference in y1, the gain K of the Kalman filter is calculated:

[0170] K=kalman(A,[B,G],C,[D,H],Q,R,N)

[0171] Where Q and R are the variance matrices, and N is the covariance matrix of the road input and the measurement noise.

[0172] After obtaining the gain of the Kalman filter, we can use y1 = [ω] meaf -ω torqf ω mear -ω torqr ] T That is, the front wheel speed difference and the rear wheel speed difference, and By considering the front wheel displacement, the derivative of the front wheel displacement with time, the rear wheel displacement, the derivative of the rear wheel displacement with time, the vehicle bounce displacement, and the derivative of the vehicle bounce displacement with time, we can determine θ. p and

[0173] Figure 10 This is a schematic diagram of the pitch angle estimation algorithm, as shown below. Figure 10 As shown, the measured front wheel speed and measured rear wheel speed are obtained. Based on the front wheel torque and rear wheel torque, the front drive wheel speed and rear drive wheel speed can be calculated. Then, the difference in front wheel speed is calculated, and then estimated using a Kalman filter model to obtain the pitch angle change and pitch angle.

[0174] When estimating the pitch angle using the method of this embodiment, it is no longer necessary to set up a separate pitch angle sensor, which reduces the hardware cost of the vehicle. Furthermore, the estimation process can improve the accuracy of the estimation because it takes into account the vehicle load, pitch, turbulence, and the influence of drive on wheel speed.

[0175] For vehicle data acquisition, wheel speed signals are received from the ESP / ECU via CAN communication. Generally, the vehicle's pitch resonance frequency is around 1.5Hz. Therefore, the pitch angle can be calculated by extracting data within a preset frequency range of around 1.5Hz from the wheel speed information. To eliminate measurement noise, one implementation uses a third-order bandpass Butterworth filter with a cutoff frequency of 0.5Hz to 3.5Hz to perform frequency filtering on the initially acquired data.

[0176] In some embodiments, in the Kalman filter design, y2 is assumed to be a white noise road input, and the noise from the wheel rolling speed sensor is 0.2 rad / s. To eliminate the constant vehicle speed, a third-order high-pass Butterworth filter with a cutoff frequency of 0.5 Hz is used.

[0177] For example, Figure 11 This diagram illustrates the estimated and measured pitch angle values. When the vehicle is traveling at a constant speed of 80 km / h on the road, the estimated and measured pitch angle rates are as follows: Figure 11As shown, the dashed line represents the measured value, and the solid line represents the estimated value. This demonstrates that the estimated value matches the measured value well. Therefore, this estimation method can be used to replace displacement and acceleration state measurement sensors and solve the problem of inaccuracy in other estimation methods.

[0178] In addition, after obtaining the estimated pitch angle, the vehicle can be controlled based on the pitch angle to reduce vehicle pitch changes and improve user experience.

[0179] When the user presses the accelerator, the engine / motor torque is transmitted to the vehicle body, causing the front half of the vehicle to pitch up. Conversely, when the accelerator is released, the engine / motor torque decreases, causing the front half of the vehicle to drop down. If pitch changes occur on uneven surfaces, controlling the torque can keep the vehicle's attitude level.

[0180] Car suspensions are typically equipped with shock absorbers to suppress vertical swaying. If the shock absorbers are effective, swaying on uneven surfaces can be stopped quickly, and vice versa. Applying slight braking while driving on uneven surfaces can improve the performance of the shock absorbers; therefore, a technology has been developed that automatically applies slight braking momentarily when traversing uneven surfaces, thereby suppressing overall vehicle swaying.

[0181] During vehicle operation, the braking and driving forces (or inertial forces) acting on the vehicle body during acceleration and deceleration, causing pitch and sway, are reflected in the torque acting between the wheels (specifically, the drive wheels during driving) and the road surface. A vehicle vibration damping control device includes a braking / acceleration torque generating component, a correction torque calculation component, a correction torque command value output component, and a priority setting component. The braking / acceleration torque generating component is configured to generate braking / acceleration torque in the wheels. The correction torque calculation component is capable of calculating a correction torque to suppress vehicle pitch and buoyancy vibrations based on a predicted pitch angle. The correction torque command value output component is configured to output a correction torque command value to the braking / acceleration torque generating component based on the correction torque. The priority setting component is configured to set a priority for calculating the correction torque command value, such that vehicle buoyancy vibrations are suppressed preferentially over vehicle pitch vibrations.

[0182] Therefore, the corrective torque can be calculated based on the estimated vehicle pitch angle, and the torque of the front and rear wheels can be controlled to make the vehicle more stable and suppress the overall vehicle sway.

[0183] This method of drive torque control based on estimated pitch angular velocity controls the vehicle's pitch performance through drive torque. In this type of vibration damping control, instead of absorbing vibration energy through the suspension, vibration energy generation is suppressed by adjusting the force source of vibration. Therefore, relatively rapid vibration damping and good energy efficiency can be achieved.

[0184] Figure 12 This is a schematic diagram of an embodiment of the vehicle pitch angle determination device provided in this application. The vehicle pitch angle determination device 1200 includes:

[0185] The acquisition module 1201 is used to acquire the measured wheel speed of the front wheels, the measured wheel speed of the rear wheels, the torque of the front wheels, the torque of the rear wheels, and the vehicle displacement.

[0186] The first determining module 1202 is used to determine the front wheel drive speed and the rear wheel drive speed respectively based on the front wheel torque and the rear wheel torque;

[0187] The second determining module 1203 is used to determine the front wheel speed difference based on the measured front wheel speed and the front wheel drive wheel speed.

[0188] The third determining module 1204 is used to determine the rear wheel speed difference based on the measured rear wheel speed and the rear wheel drive speed.

[0189] The fourth determining module 1205 is used to determine the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement.

[0190] Optionally, the fourth determining module 1205 is specifically used for:

[0191] Based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement, a predicted pitch angle is determined using a preset Kalman filter model. The Kalman filter model represents the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement, and the predicted pitch angle.

[0192] Optionally, the vehicle displacement includes front wheel displacement, rear wheel displacement, road displacement, and vehicle bounce displacement.

[0193] Optionally, the Kalman filter model is a model pre-constructed based on the front wheel speed difference, rear wheel speed difference, front wheel displacement, the derivative of front wheel displacement with time, rear wheel displacement, the derivative of rear wheel displacement with time, vehicle bounce displacement, pitch angle, and the derivative of pitch angle with time.

[0194] Optionally, the first determining module 1202 is specifically used for:

[0195] Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a first formula. The first formula is used to represent the mapping relationship between the front wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque.

[0196] Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a second formula. The second formula is used to represent the mapping relationship between the rear wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque.

[0197] Optionally, the second determining module 1203 is specifically used for:

[0198] The front wheel speed difference is obtained by subtracting the front wheel drive wheel speed from the measured front wheel speed.

[0199] Accordingly, the third determining module 1204 is specifically used for:

[0200] The rear wheel speed difference is obtained by subtracting the measured rear wheel speed from the rear wheel drive wheel speed. Optionally, the device further includes a control module 1206, which is specifically used for:

[0201] The estimated pitch angle is used to control the front and rear wheel torques of the vehicle.

[0202] The vehicle pitch angle determination device 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.

[0203] Figure 13 A schematic diagram of the structure of the electronic device provided in this application. Figure 13 As shown, the electronic device 50 provided in this embodiment can be any controller in a vehicle. The electronic device 50 includes at least one processor 501 and a memory 502. Optionally, the device 50 also includes a communication component 503. The processor 501, memory 502, and communication component 503 are connected via a bus 504.

[0204] In a specific implementation, at least one processor 501 executes computer execution instructions stored in memory 502, causing at least one processor 501 to perform the above-described method.

[0205] The specific implementation process of processor 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0206] 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.

[0207] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0208] 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.

[0209] This application also provides a vehicle including a vehicle controller that can implement the above-described methods.

[0210] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0211] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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 the pitch angle of a vehicle, characterized in that, The method includes: The system acquires the measured wheel speeds of the front and rear wheels, the torque of the front and rear wheels, and the vehicle displacement; the vehicle displacement includes the front wheel displacement, the rear wheel displacement, the road displacement, and the vehicle bounce displacement. The front wheel drive speed and the rear wheel drive speed are determined based on the front wheel torque and the rear wheel torque, respectively. The front wheel speed difference is determined based on the measured front wheel speed and the front wheel drive speed. The difference in rear wheel speed is determined based on the measured rear wheel speed and the rear wheel drive speed. The estimated pitch angle is determined based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement.

2. The method according to claim 1, characterized in that, The step of determining the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement includes: Based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement, a predicted pitch angle is determined using a preset Kalman filter model. The Kalman filter model represents the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement, and the predicted pitch angle.

3. The method according to claim 2, characterized in that, The Kalman filter model is a model pre-constructed based on the front wheel speed difference, rear wheel speed difference, front wheel displacement, the derivative of front wheel displacement with time, rear wheel displacement, the derivative of rear wheel displacement with time, vehicle bounce displacement, pitch angle, and the derivative of pitch angle with time.

4. The method according to any one of claims 1 to 3, characterized in that, The step of determining the front-wheel drive speed and the rear-wheel drive speed based on the front wheel torque and the rear wheel torque respectively includes: Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a first formula. The first formula is used to represent the mapping relationship between the front wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque. Based on the front wheel torque and the rear wheel torque, the front wheel drive speed is determined by a second formula. The second formula is used to represent the mapping relationship between the rear wheel torque speed and the front wheel torque, rear wheel torque, front wheel radius, rear wheel radius, vehicle mass, front wheel inertial torque, and rear wheel inertial torque.

5. The method according to any one of claims 1 to 3, characterized in that, The step of determining the front wheel speed difference based on the measured front wheel speed and the front wheel drive wheel speed includes: The front wheel speed difference is obtained by subtracting the front wheel drive wheel speed from the measured front wheel speed. Accordingly, determining the rear wheel speed difference based on the measured rear wheel speed and the rear wheel drive wheel speed includes: The difference in rear wheel speed is obtained by subtracting the measured rear wheel speed from the rear wheel drive speed.

6. The method according to any one of claims 1 to 3, characterized in that, The method further includes: The estimated pitch angle is used to control the front and rear wheel torques of the vehicle.

7. A device for determining the pitch angle of a vehicle, characterized in that, The device includes: The acquisition module is used to acquire the measured wheel speed of the front wheels, the measured wheel speed of the rear wheels, the torque of the front wheels, the torque of the rear wheels, and the vehicle displacement; the vehicle displacement includes the front wheel displacement, the rear wheel displacement, the road displacement, and the vehicle bounce displacement. The first determining module is used to determine the front wheel drive speed and the rear wheel drive speed based on the front wheel torque and the rear wheel torque, respectively. The second determining module is used to determine the front wheel speed difference based on the measured front wheel speed and the front wheel drive wheel speed. The third determining module is used to determine the rear wheel speed difference based on the measured rear wheel speed and the rear wheel drive speed. The fourth determining module is used to determine the estimated pitch angle based on the front wheel speed difference, the rear wheel speed difference, and the vehicle displacement.

8. A controller, 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 1-6.

9. A vehicle, characterized in that, The vehicle includes a controller for performing the method as described in any one of claims 1-6.

10. 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 1-6.

11. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method described in any one of claims 1-6.

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