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

Abstract

The invention provides a vehicle pitch angle determination method and device, a controller, a vehicle and a storage medium. The method comprises the steps that the front wheel actual measurement wheel speed, the rear wheel actual measurement wheel speed, the front wheel torque, the rear wheel torque and the vehicle displacement of the vehicle are obtained; according to the front wheel torque and the rear wheel torque, the front wheel driving wheel speed and the rear wheel driving wheel speed are determined respectively; a front wheel speed difference value is determined according to the front wheel actually-measured wheel speed and the front wheel driving wheel speed; according to the rear wheel actual measurement wheel speed and the rear wheel driving wheel speed, the rear wheel speed difference value is determined; and according to the front wheel speed difference value, the rear wheel speed difference value and the vehicle displacement, an estimated pitch angle is determined. According to the method, the effect of estimating the pitch angle under the condition that a pitch angle test sensor is not used is achieved only by knowing the wheel speed, the torque and the displacement of the vehicle, the influence of torque, load fluctuation and suspension deflection fluctuation is introduced, and the estimation accuracy is improved.

Description

Technical Field

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

[0002] When a vehicle is driving, it will produce pitch motion due to uneven road surface, acceleration, deceleration, etc., that is, the tilt angle of the vehicle in the front and rear direction changes. The pitch angle of the vehicle not only affects the driving stability and ride comfort of the vehicle, but also directly affects 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 an inertial measurement unit (IMU), which will undoubtedly increase the hardware cost. To solve this problem, one solution is to obtain the vehicle pitch angle based on the offset between the actual acceleration of the vehicle and the measured longitudinal acceleration, but this has the problem of low accuracy.

[0004] Therefore, how to accurately estimate the pitch angle without using a pitch angle test sensor is an urgent problem to be solved. Summary of the invention

[0005] The present application provides a method, device, controller, vehicle and storage medium for determining the pitch angle of a vehicle, so as to achieve the effect of estimating 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 the front wheel measured speed, rear wheel measured speed, front wheel torque, rear wheel torque and vehicle displacement of the vehicle;

[0008] Determining a front wheel drive speed and a rear wheel drive speed respectively according to the front wheel torque and the rear wheel torque;

[0009] Determining a front wheel speed difference according to the front wheel measured wheel speed and the front wheel drive wheel speed;

[0010] Determining a rear wheel speed difference according to the measured rear wheel speed and the rear wheel drive speed;

[0011] An estimated pitch angle is determined according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement.

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

[0013] The estimated pitch angle is determined according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement through a preset Kalman filter model, and the Kalman filter model is used to represent the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement and the estimated pitch angle.

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

[0015] 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.

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

[0017] Determine the front wheel drive speed according to the front wheel torque and the rear wheel torque by a first formula, wherein the first formula is used to express a mapping relationship between the front 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;

[0018] The front wheel drive speed is determined according to the front wheel torque and the rear wheel torque by a second formula, wherein the second formula is used to represent a mapping relationship between the 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 manner, determining the front wheel speed difference according to the front wheel measured wheel speed and the front wheel driving wheel speed includes:

[0020] Subtracting the front wheel driving speed from the front wheel measured wheel speed to obtain the front wheel speed difference;

[0021] Accordingly, determining the rear wheel speed difference according to the rear wheel measured wheel speed and the rear wheel driving wheel speed comprises:

[0022] The rear wheel speed difference is obtained by subtracting the rear wheel driving speed from the rear wheel actual wheel 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 estimated pitch angle.

[0025] In a second aspect, the present application further provides a device for determining a vehicle pitch angle, the device comprising:

[0026] An acquisition module, used to acquire the front wheel measured speed, rear wheel measured speed, front wheel torque, rear wheel torque and vehicle displacement of the vehicle;

[0027] A first determination module, configured to determine a front wheel driving speed and a rear wheel driving speed according to the front wheel torque and the rear wheel torque, respectively;

[0028] A second determination module, configured to determine a front wheel speed difference according to the front wheel measured wheel speed and the front wheel driving wheel speed;

[0029] A third determination module, configured to determine a rear wheel speed difference according to the measured rear wheel speed and the rear wheel driving speed;

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

[0031] In a possible implementation manner, the fourth determining module is specifically configured to:

[0032] The estimated pitch angle is determined according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement through a preset Kalman filter model, and the Kalman filter model is used to represent the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement and the estimated pitch angle.

[0033] In a possible implementation manner, 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 a possible implementation manner, the first determining module is specifically configured to:

[0036] Determine the front wheel drive speed according to the front wheel torque and the rear wheel torque by a first formula, wherein the first formula is used to express a mapping relationship between the front 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;

[0037] The front wheel drive speed is determined according to the front wheel torque and the rear wheel torque by a second formula, wherein the second formula is used to represent a mapping relationship between the 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.

[0038] In a possible implementation manner, the second determining module is specifically configured to:

[0039] Subtracting the front wheel driving speed from the front wheel measured wheel speed to obtain the front wheel speed difference;

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

[0041] The rear wheel speed difference is obtained by subtracting the rear wheel driving speed from the rear wheel actual wheel speed.

[0042] Optionally, the device further includes a control module, and the control module is specifically configured to:

[0043] The front wheel torque and the rear wheel torque of the vehicle are controlled according to the estimated pitch angle.

[0044] In a third aspect, the present application further provides a controller, including: a memory, a processor;

[0045] The memory stores computer-executable instructions;

[0046] The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method as described in any one of the first aspects.

[0047] In a fourth aspect, the present application further provides a vehicle, comprising a controller, wherein the controller is configured to execute the method as described in any one of the first aspects.

[0048] In a fifth aspect, the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, they are used to implement the method as described in any one of the first aspects.

[0049] In a sixth aspect, the present application further provides a computer program product, comprising a computer program, which, when executed by a processor, is used to implement the method as described in any one of the first aspects.

[0050] The present application provides a method, device, controller, vehicle and storage medium for determining the pitch angle of a vehicle. The method includes: obtaining the measured wheel speed of the front wheel, the measured wheel speed of the rear wheel, the front wheel torque, the rear wheel torque and the vehicle displacement of the vehicle; determining the front wheel drive wheel speed and the rear wheel drive wheel speed respectively according to the front wheel torque and the rear wheel torque; determining the front wheel speed difference according to the measured wheel speed of the front wheel and the front wheel drive wheel speed; determining the rear wheel speed difference according to the measured wheel speed of the rear wheel and the rear wheel drive wheel speed; determining the estimated pitch angle according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement. This method only requires knowing the vehicle wheel speed, torque and displacement to achieve the effect of estimating the pitch angle without using a pitch angle test sensor, and this method comprehensively considers the influence of torque, load fluctuation and suspension disturbance fluctuation to improve the estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

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

[0053] Figure 2 A flowchart of a first embodiment of a method for determining a vehicle pitch angle provided in the present application;

[0054] Figure 3 The wheel speed changes with the vehicle body pitch. Figure 1 ;

[0055] Figure 4 Schematic diagram of the wheel movement changing with the pitch of the vehicle body Figure 2 ;

[0056] Figure 5 Schematic diagram of wheel speed changing with suspension deflection Figure 1 ;

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

[0058] Figure 7 It is a schematic diagram of the change of wheel speed with load;

[0059] Figure 8 is the variation of the effective rolling radius and load radius of the tire with the wheel load fluctuation;

[0060] Fig. 9 It is the driving torque schematic diagram of the whole vehicle model;

[0061] Fig.10 Schematic diagram of pitch angle estimation algorithm;

[0062] Fig.11 A schematic diagram of the estimated and measured values ​​of the pitch angle;

[0063] Fig.12 A schematic structural diagram of an embodiment of a device for determining a pitch angle of a vehicle provided in the present application;

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

[0065] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0066] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0067] First, the terms involved in this application are explained:

[0068] Vehicle pitch angle: refers to the pitch movement of the vehicle during driving due to uneven road surface, acceleration, deceleration, etc., that is, the change in the tilt angle of the vehicle in the front and rear direction.

[0069] The pitch angle of a vehicle not only affects the vehicle's driving stability and ride comfort, but is also directly related to the vehicle's handling performance and safety. Therefore, it is of great significance to accurately calculate and monitor the pitch angle of the vehicle.

[0070] Figure 1 A schematic diagram of a vehicle pitch angle determination scenario provided in this application, such as Figure 1 As shown in the figure, during the driving process, the rear end of the vehicle decelerates and deviates higher than the front end of the vehicle, causing the vehicle to tilt at a different angle. In other scenarios, the front and rear ends of the vehicle may tilt due to uneven roadside.

[0071] In combination with the above scenario, it can be seen that in the prior art, the pitch angle of the vehicle is mainly measured by setting an inertial measurement unit (IMU) on the vehicle body, and the equipment is expensive. To solve this problem, some solutions estimate the pitch angle of the vehicle by measuring the lateral acceleration, longitudinal acceleration, and yaw angular velocity of the vehicle. This method still requires an acceleration measurement unit and does not consider the pitch change caused by the change in vehicle dynamics, which will lead to the problem of low estimation accuracy.

[0072] In view of this, the inventors, in the process of studying this field, started from the principles of vehicle kinematics and took into account the changes in wheel speed with vehicle body pitch, suspension deflection, wheel load fluctuation and drive torque, and constructed a calculation model that can estimate the pitch angle, thereby improving the accuracy of pitch angle estimation and saving the cost of sensors for measuring pitch angles.

[0073] The pitch angle determination method provided in the present application can be used not only for four-wheel drive vehicles, but also for front-wheel drive vehicles or rear-wheel drive vehicles. There is no restriction on the energy type of the vehicle, which can be a fuel vehicle, a new energy vehicle, or a hybrid vehicle.

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

[0075] Figure 2 The process diagram of the first embodiment of the method for determining the pitch angle of a vehicle provided in this application is as follows: Figure 2 As shown, the method includes:

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

[0077] In this step, the measured wheel speeds of the front wheels and the measured wheel speeds of the rear wheels of the vehicle are obtained through wheel speed sensors, wherein the configuration and principle of the wheel speed sensors are as follows: the wheel speed sensors consist of two parts, the rotating part is mounted on the wheel hub or the brake drum, and the fixed part is mounted on the steering knuckle or the brake bracket. Since the rotating part and the fixed part are separated, the wheel speed varies with the vehicle body pitch, suspension deflection, and wheel load fluctuations. Therefore, the vehicle posture state, such as vehicle body pitch, suspension deflection, and wheel load fluctuations, can be estimated by using the wheel speed changes.

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

[0079] The vehicle displacement includes the front wheel displacement, rear wheel displacement, road displacement and vehicle bounce displacement, which can be measured by a pre-set displacement sensor to obtain the displacement value of each position relative to each reference position at the measurement time. Among them, the front wheel bounce displacement represents the vertical displacement of the front body position relative to the front body reference position, the rear wheel bounce displacement represents the vertical displacement of the rear body position relative to the rear body reference position, the front wheel displacement represents the vertical displacement of the front wheel center relative to the front wheel center reference position, the rear wheel displacement represents the vertical displacement of the rear wheel center relative to the rear wheel center reference position, and the road displacement includes the front wheel road input displacement (i.e., the road height change of the front wheel contact point) and the rear wheel road input displacement (the road height change of the rear wheel contact point). The road input displacement of the front and rear wheel contact points can be obtained by a high-precision ground sensor or a laser scanning system. For example, the vehicle can be equipped with a ground sensor to monitor the road height change, thereby calculating the road displacement of the wheel contact point. The vehicle's bounce displacement can be monitored by a special body vibration sensor or a suspension system sensor, which can monitor the vibration and bounce displacement of the upper and lower body of the vehicle in real time. It should be noted that if it is a front-wheel drive vehicle, the rear wheel torque is 0, and if it is a rear-wheel drive vehicle, the front wheel torque is 0.

[0080] S102: Determine the front wheel drive speed and the rear wheel drive speed according to the front wheel torque and the rear wheel torque, respectively.

[0081] In this step, when the vehicle is actually driving, due to road conditions or user acceleration and deceleration operations, the vehicle pitch changes, and the front wheel drive speed and rear wheel drive speed change in the form of vehicle data. Therefore, when predicting the pitch angle of the vehicle, the front wheel drive speed and rear wheel drive speed must be determined first. It should be noted that the drive wheel speed determined in this step is a theoretical value calculated based on the torque loaded on the wheel, rather than an actual measured value.

[0082] How to calculate the front wheel drive speed and the rear wheel drive speed can be determined by the preset first formula and second formula. The first formula is used to express 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 inertia torque, and rear wheel inertia torque. The second formula is used to express 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 inertia torque, and rear wheel inertia torque.

[0083] The first formula and the second formula are derived in advance based on the vehicle kinematics equation and are used to calculate the front wheel drive speed and the rear wheel drive speed. The specific derivation process will be introduced later. The first formula and the second formula can be expressed as follows:

[0084] First formula:

[0085] Second formula:

[0086] Among them, w torqf represents the front wheel drive speed, w torqr Represents the rear wheel drive speed, T f Represents the front wheel torque, T f Represents the rear wheel torque, r f Represents the front wheel radius, r r Represents the rear wheel radius, I wf represents the inertia torque of the front wheel, I wr Represents the inertia torque of the rear wheels.

[0087] In some embodiments, r f is the actual tested front wheel radius, i.e. the distance from the center of the front wheel to the ground; r r is the actual tested rear wheel radius, which indicates the distance from the rear wheel center to the ground. wf The inertia torque of the front wheel is a fixed value, I wr The inertia torque of the rear wheel is a fixed value.

[0088] The front wheel torque and rear wheel torque collected in real time are integrated over time to obtain the front wheel drive speed and rear wheel drive speed respectively.

[0089] S103: Determine the front wheel speed difference according to the front wheel actually measured wheel speed and the front wheel drive wheel speed.

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

[0091] S104: Determine a rear wheel speed difference according to the measured rear wheel speed and the rear wheel drive speed.

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

[0093] S105: Determine an estimated pitch angle according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement.

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

[0095] During vehicle driving, wheel speed is affected by vehicle body pitch, suspension deflection, wheel load fluctuation and driving torque change. Therefore, the wheel speed change can be used to estimate the vehicle attitude state, such as vehicle body pitch, suspension deflection and wheel load fluctuation. The total wheel speed signal (i.e., measured wheel speed) can be written as:

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

[0097] Among them, ω body ,ω sus ,ω tire ,ω toq They are the changes in wheel speed with vehicle body pitch, suspension deflection, wheel load fluctuation and drive torque. total Indicates the total wheel speed, that is, the measured wheel speed.

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

[0099] Figure 3 The wheel speed changes with the pitch of the vehicle body. Figure 1 , Figure 3 As shown, h is the center of gravity of the vehicle body O b The height from the ground, r is the effective rolling radius of the wheel, L p It is from O b Length to wheel center O, YesL p The angle between the horizontal direction and the p is the vehicle body pitch angle.

[0100] Figure 4 Schematic diagram of the wheel movement changing with the pitch of the vehicle body Figure 2 , due to θ p The value is small, the pitch angle has an influence on L p The impact of the change is small, so L p Changes:

[0101]

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

[0103]

[0104] In the formula, θ w is the wheel rolling angle. Figure 4 It can be seen that:

[0105]

[0106] In the wheel speed sensor, the fixed part changes with the vehicle body pitch angle θ p Rotation, the angle of rotation is equal to θ w , so the wheel speed change caused by the vehicle body pitch can be written as:

[0107]

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

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

[0110] Figure 5 Schematic diagram of wheel speed changing with suspension deflection Figure 1 , Figure 5 As shown in Figure 2, the wheel speed varies with the suspension deflection z s And change, O s is the instantaneous rotation center of the suspension, O g is the contact point between the wheel and the ground, L s It is from O s The length from O to the wheel center, L is the length from O s The horizontal length θ0 to O is OO s The angle between the horizontal and the horizontal direction is O g O s The angle between the z s is the suspension deflection.

[0111] Figure 6 Illustration of 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 is the wheel rolling angle. Since the fixed part of the wheel speed sensor is around O s Rotation θ r ,therefore:

[0114] L s1 ≈L s

[0115] Among them, L s1 It is from O s Length to O, around the fixed part O s The rotation value:

[0116]

[0117] Among them, θ r The fixed part is around Os The rotation angle of Figure 5 , Figure 6 It can be seen that

[0118]

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

[0120]

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

[0122] Ltanθ=Ltanθ0+r

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

[0124]

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

[0126] Figure 7 It is a schematic diagram of the change of wheel speed with load, such as Figure 7 As shown, the wheel is under normal load F z Rolling at a speed V under the action of free That is, the free radius without deformation in the figure, r load is the loading radius, i.e. the radius after full load, and r is the effective rolling radius after a certain load is loaded. The rolling speed ω is:

[0127]

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

[0129]

[0130] Where δr is the difference in r, and the measured value of δr changes with the wheel load δF z The effective rolling radius can be calculated by the normal load increment, the slope and curvature of the road longitudinal section. Due to the complexity of the actual road longitudinal section, it is difficult to describe δr and δF with a simple function. z Such as Figure 7 As shown, the difference in tire loading radius δr load With δF zProportional, that is, the greater the load change, the greater the change in tire loading radius, so it can be written as:

[0131]

[0132] In the formula, k t is the tire radial stiffness, δr load With δF z The measurement relationship between Figure 8 As shown, Figure 8 is the variation of the effective rolling radius and load radius of the tire with the wheel load fluctuation. In the actual application of the tire model, The gradient of F z Department The gradient of is approximately proportional to:

[0133]

[0134] In the formula, η(F z ) is the ratio value. It is a constant within the wheel load fluctuation range, although η(F z ) value varies with F z However, a constant can be used. Therefore, the wheel speed change caused by wheel load can be written as:

[0135]

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

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

[0138] Fig. 9 The schematic diagram of the driving torque of the vehicle model shows that the torques at the front and rear wheel axles are T f and T r , V and V b are the body and wheel speeds, F xf and F xr The front and rear axle drive forces are respectively, M b 、M wf and M wr is the mass of the vehicle body, front wheels and rear wheels, I wf and I wr are the wheel inertia torques respectively. The vehicle motion equation can be written as:

[0139]

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

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

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

[0143]

[0144] In summary, in actual vehicle tests, ω body ,ω sus ,ω tire and ω toq The value of can be calculated using the vehicle design parameters and the values ​​of the measured state variables to obtain the total vehicle wheel speed. Therefore, the total wheel speed ω is obtained by the wheel speed sensor total After that, the change of the pitch angle to the wheel speed can be solved in reverse, and then the pitch angle can be solved. It should be noted that if it is a front-wheel drive or rear-wheel drive vehicle, the pitch angle can be solved only by the wheel speed with driving force.

[0145] In one solution, if the above formulas are used to solve, ω is obtained. body , and then calculate the pitch angle, which requires real-time measurement of disturbance changes, wheel load changes, and loading radius changes, which requires too many state quantities to be measured. Therefore, the vehicle attitude state variables are estimated through the Kalman filter model, covering the pitch angle, wheel load fluctuations, and suspension deflection changes, which maps the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement, and the estimated pitch angle. For the matrix parameters in the Kalman filter model, they are determined in advance through the mapping relationship between the actual measured pitch angle and the wheel speed difference and other parameters, which are 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 a letter represents the first derivative of the physical quantity with respect to time, and two dots above a letter represent the second derivative of the physical quantity with respect to time. bf represents the front wheel bounce displacement (i.e. the vertical displacement of the front vehicle body position), z br Represents the rear wheel bounce displacement (vertical displacement of the rear body position), z wf represents 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 represents the front wheel road input displacement (i.e. the change in road 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 refers to the front wheel and subscript r refers to the rear wheel), θ p Center of gravity b The pitch angle at k sf is the front wheel suspension stiffness, k sr Rear wheel suspension stiffness, c sf is the front wheel damping coefficient, c sr is the rear wheel damping coefficient, k tf is the front tire stiffness and k tr is the rear tire stiffness, m b and I p are the vehicle body mass and pitch inertia, m wf is the mass of the front wheel, m wr is the mass of the rear wheel. The overall vehicle bounce displacement z can be determined based on the front wheel bounce displacement and the rear wheel bounce displacement b .

[0147] The vehicle motion equation for road input is as follows:

[0148]

[0149]

[0150]

[0151]

[0152] z sf =z wf -z bf

[0153] z sr =z wr -z br

[0154] Where, L f and L r From O b To the front and rear center of gravity O bf and O br Wheel load fluctuation δF zf and δF zr It can be written as:

[0155] δF zf =k tf (z 0f -z wf )

[0156] δF zr =k tr (z 0r -zwr )

[0157] Substituting the above equation into w torqr and w torqf The calculation formula is:

[0158]

[0159] y1=C1x1+H1y2

[0160] in,

[0161] y1=[ω meaf -ω torqf ω mear -ω torqr ] T

[0162]

[0163] ω meaf is the measured front wheel speed, ω mear is the measured wheel speed of the rear wheel, 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.

[0164] The road input y2 is:

[0165]

[0166] y2=C2x2+D2w

[0167] In one embodiment, A2 = [0 0; 0 0], B2 = [1 0; 0 1], C2 = B2, D2 = A2, x2 = [z 0f z 0r ] T , y2=x2,

[0168] Therefore, the expanded equation can be obtained as:

[0169]

[0170] y=Cx+Du+Hw

[0171] Where x = [x1 x2] T ,u=[0 0] T ,y=y1, C=[C1 H1C2],D=D1,H=[H1D2]

[0172] On the basis of the extended equation, the gain K of the Kalman filter is calculated according to the actually measured front wheel displacement, front wheel displacement and time derivative, rear wheel displacement, rear wheel displacement and time derivative, vehicle bounce displacement, pitch angle, pitch angle and time derivative in x1, and front wheel speed difference and rear wheel speed difference in y1:

[0173] K=kalman(A,[B,G],C,[D,H],Q,R,N)

[0174] Where Q and R are the variance matrices, respectively, and N is the covariance matrix of the road input and measurement noise.

[0175] After obtaining the gain of the Kalman filter, we can use y1 = [ω meaf -ω torqf ω mear -ω torqr ] T , that is, the difference between the front wheel speed and the rear wheel speed, and x1 =

[0176] 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 can determine θ p and

[0177] Fig.10 is a schematic diagram of the pitch angle estimation algorithm, as shown in Fig.10 As shown, the measured front wheel speed and the measured rear wheel speed are obtained; the front wheel drive speed and the rear wheel drive speed can be calculated according to the front wheel torque and the rear wheel torque. Then the front wheel speed difference is calculated, and then estimated through the Kalman filter model, so that the pitch angle change and the pitch angle can be obtained.

[0178] When estimating the pitch angle using the method of this embodiment, there is no need to set up a pitch angle sensor separately, which reduces the hardware cost of the vehicle. In addition, the estimation process takes into account the impact of vehicle load, pitch, disturbance and drive on wheel speed, which can improve the accuracy of the estimation.

[0179] For the acquisition of vehicle data, wheel speed signals are received from ESP / ECU via CAN communication. Generally speaking, the pitch resonance frequency of the vehicle is around 1.5Hz. Therefore, the pitch angle can be calculated by extracting data within a preset frequency range of 1.5Hz from the wheel speed information. In order to eliminate measurement noise, in one implementation, a third-order bandpass Butterworth filter with a cutoff frequency of 0.5Hz to 3.5Hz is used to perform frequency filtering on the initially acquired data.

[0180] In some embodiments, in the Kalman filter design, y2 is assumed to be a white noise road input, and the noise of the wheel rolling speed sensor is 0.2 rad / s. In order to eliminate the constant value of the vehicle speed, a third-order high-pass Butterworth filter with a cutoff frequency of 0.5 Hz is used.

[0181] For example, Fig.11 Figure 1 is a schematic diagram of the estimated and measured values ​​of the pitch angle. When the vehicle is traveling on the road at a constant speed of 80 km / h, the estimated and measured values ​​of the pitch angle velocity are as follows: Fig.11 As shown in the figure, the dotted line is the measured value and the solid line is the estimated value. It can be seen that the estimated value is consistent with the measured value. Therefore, this estimation method can be used to replace the displacement and acceleration state measurement sensor and solve the problem of inaccuracy of other estimation methods.

[0182] In addition, after obtaining the estimated pitch angle, the vehicle can be controlled according to the pitch angle to reduce the pitch change of the vehicle and improve the user experience.

[0183] When the user steps on the accelerator, the engine / motor torque is transmitted to the vehicle body, and the front half of the vehicle body will pitch up. Conversely, when the accelerator is released, the engine / motor torque decreases, and the front half of the vehicle body will sink. If the pitch angle changes on an uneven road surface, the torque can be controlled to keep the vehicle posture level.

[0184] The suspension of a car is generally equipped with a shock absorber that can suppress the shaking in the up and down directions. If the shock absorber is effective, the shaking on the uneven road surface can be stopped in time, and vice versa. When driving on uneven roads, applying slight brakes can improve the performance of the shock absorber, so a technology has been developed to automatically apply weak brakes instantly when crossing uneven roads, thereby suppressing the shaking of the entire vehicle.

[0185] During the running of the vehicle, the braking and driving forces (or inertial forces) acting on the vehicle body and causing pitch-bounce when the vehicle is accelerated and decelerated are reflected in the torque acting between the wheels (specifically, the driving wheels during driving) and the road surface. A vehicle vibration reduction 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 a braking / acceleration torque in the wheel. The correction torque calculation component is capable of calculating a correction torque for suppressing the pitch vibration of the vehicle and the heave vibration of the vehicle according to the predicted pitch angle. The correction torque command value output component is configured to output a correction torque command value braking / acceleration torque generating component according to the correction torque. The priority setting component is configured to set a priority for calculating the correction torque command value so that the heave vibration of the vehicle is suppressed preferentially over the pitch vibration of the vehicle.

[0186] Therefore, the correction torque can be calculated based on the estimated vehicle pitch angle to control the front wheel torque and rear wheel torque to make the vehicle more stable and suppress the shaking of the entire vehicle.

[0187] Through this driving torque control method based on the estimated pitch angular velocity, the pitch performance of the entire vehicle is controlled by the driving torque. In the case of this type of vibration reduction control, the vibration reduction control is no longer performed by absorbing the vibration energy generated by the suspension, but by adjusting the vibration generating force source to suppress the generation of vibration energy, so that a relatively rapid vibration reduction effect and good energy efficiency can be advantageously obtained.

[0188] Fig.12 This is a schematic diagram of the structure of an embodiment of a device for determining a pitch angle of a vehicle provided in the present application. The device 1200 for determining a pitch angle of a vehicle includes:

[0189] An acquisition module 1201 is used to acquire the front wheel actual speed, rear wheel actual speed, front wheel torque, rear wheel torque and vehicle displacement of the vehicle;

[0190] A first determination module 1202, configured to determine a front wheel driving speed and a rear wheel driving speed according to the front wheel torque and the rear wheel torque, respectively;

[0191] A second determining module 1203 is used to determine a front wheel speed difference according to the front wheel measured wheel speed and the front wheel driving wheel speed;

[0192] A third determining module 1204 is used to determine a rear wheel speed difference according to the measured rear wheel speed and the rear wheel driving speed;

[0193] The fourth determination module 1205 is used to determine the estimated pitch angle according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement.

[0194] Optionally, the fourth determining module 1205 is specifically configured to:

[0195] The estimated pitch angle is determined according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement through a preset Kalman filter model, and the Kalman filter model is used to represent the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement and the estimated pitch angle.

[0196] Optionally, the vehicle displacement includes front wheel displacement, rear wheel displacement, road displacement and vehicle bounce displacement.

[0197] Optionally, 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.

[0198] Optionally, the first determining module 1202 is specifically configured to:

[0199] Determine the front wheel drive speed according to the front wheel torque and the rear wheel torque by a first formula, wherein the first formula is used to express a mapping relationship between the front 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;

[0200] The front wheel drive speed is determined according to the front wheel torque and the rear wheel torque by a second formula, wherein the second formula is used to represent a mapping relationship between the 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.

[0201] Optionally, the second determining module 1203 is specifically configured to:

[0202] Subtracting the front wheel driving speed from the front wheel measured wheel speed to obtain the front wheel speed difference;

[0203] Accordingly, the third determining module 1204 is specifically configured to:

[0204] The rear wheel speed difference is obtained by subtracting the rear wheel driving speed from the rear wheel actual wheel speed.

[0205] Optionally, the device further includes a control module 1206, and the control module 1206 is specifically configured to:

[0206] The front wheel torque and the rear wheel torque of the vehicle are controlled according to the estimated pitch angle.

[0207] The device for determining the pitch angle of a vehicle provided in this embodiment can execute the method provided in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be described in detail here.

[0208] Fig.13 This is a schematic diagram of the structure of the electronic device provided in this application. Fig.13 As shown, the electronic device 50 provided in this embodiment can be any controller in a vehicle, and 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, the memory 502 and the communication component 503 are connected via a bus 504.

[0209] In a specific implementation process, at least one processor 501 executes the computer-executable instructions stored in the memory 502, so that at least one processor 501 executes the above method.

[0210] The specific implementation process of the processor 501 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0211] In the above embodiments, it should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the invention may be directly implemented as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0212] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0213] The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of the present application is not limited to only one bus or one type of bus.

[0214] The present application also provides a vehicle, including a vehicle controller, which can implement the above method.

[0215] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0216] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0217] The above-mentioned 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 memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0218] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium 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 be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0219] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0220] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0221] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0222] If the function is implemented in the form of 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 the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0223] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0224] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for determining a vehicle pitch angle, characterized in that: The method comprises: Obtaining the front wheel measured speed, rear wheel measured speed, front wheel torque, rear wheel torque and vehicle displacement of the vehicle; Determining a front wheel drive speed and a rear wheel drive speed respectively according to the front wheel torque and the rear wheel torque; Determining a front wheel speed difference according to the front wheel measured wheel speed and the front wheel drive wheel speed; Determining a rear wheel speed difference according to the measured rear wheel speed and the rear wheel drive speed; An estimated pitch angle is determined according to 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 according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement comprises: The estimated pitch angle is determined according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement through a preset Kalman filter model, and the Kalman filter model is used to represent the mapping relationship between the front wheel speed difference, the rear wheel speed difference, the vehicle displacement and the estimated pitch angle.

3. The method according to claim 2, characterized in that The vehicle displacement includes front wheel displacement, rear wheel displacement, road displacement and vehicle bounce displacement.

4. The method according to claim 3, characterized in that 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.

5. The method according to any one of claims 1 to 4, characterized in that: The determining the front wheel drive speed and the rear wheel drive speed respectively according to the front wheel torque and the rear wheel torque comprises: Determine the front wheel drive speed according to the front wheel torque and the rear wheel torque by a first formula, wherein the first formula is used to express a mapping relationship between the front 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; The front wheel drive speed is determined according to the front wheel torque and the rear wheel torque by a second formula, wherein the second formula is used to represent a mapping relationship between the 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.

6. The method according to any one of claims 1 to 4, characterized in that: Determining the front wheel speed difference according to the front wheel measured wheel speed and the front wheel driving wheel speed includes: Subtracting the front wheel driving speed from the front wheel measured wheel speed to obtain the front wheel speed difference; Accordingly, determining the rear wheel speed difference according to the rear wheel measured wheel speed and the rear wheel driving wheel speed comprises: The rear wheel speed difference is obtained by subtracting the rear wheel driving speed from the rear wheel actual wheel speed.

7. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: The front wheel torque and the rear wheel torque of the vehicle are controlled according to the estimated pitch angle.

8. A device for determining a vehicle pitch angle, characterized in that: The device comprises: An acquisition module, used to acquire the front wheel measured speed, rear wheel measured speed, front wheel torque, rear wheel torque and vehicle displacement of the vehicle; A first determination module, configured to determine a front wheel driving speed and a rear wheel driving speed according to the front wheel torque and the rear wheel torque, respectively; A second determination module, configured to determine a front wheel speed difference according to the front wheel measured wheel speed and the front wheel driving wheel speed; A third determination module, configured to determine a rear wheel speed difference according to the measured rear wheel speed and the rear wheel driving speed; The fourth determination module is used to determine the estimated pitch angle according to the front wheel speed difference, the rear wheel speed difference and the vehicle displacement.

9. A controller, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 7.

10. A vehicle, characterized in that: The vehicle comprises a controller configured to execute the method according to any one of claims 1-7.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 7 when executed by a processor.

12. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 7 when being executed by a processor.

Images