Heavy commercial vehicle yaw control system and method with delay compensation and slip suppression

Abstract

The application discloses a heavy commercial vehicle yaw control system with delay compensation and slip suppression, a state sensing unit collects signals and sends data to a yaw control unit and a brake force control unit. The yaw control unit obtains a desired yaw moment and a braking moment. A yaw angular velocity tracking module calculates a desired yaw angular velocity. A wheel slip suppression module obtains a slip-avoiding braking moment by control. The brake force control unit solves the brake force distribution under the yaw moment control and the wheel slip suppression, and compensates the delay of the pneumatic brake system. A brake force cooperative distribution module calculates the desired brake chamber pressure of each wheel according to the required yaw moment and the braking moment. A brake force delay compensation module calculates the predicted brake chamber pressure through a prediction model, and obtains the control input of the brake actuator through a PID controller to compensate the delay. The system improves the driving safety of the heavy commercial vehicle on complex road conditions through cooperative control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of commercial vehicle driving and control technology, and particularly relates to a heavy commercial vehicle yaw control system and method with delay compensation and slip suppression. BACKGROUND

[0002] With the increasing number of motor vehicles, the problem of road accidents and related casualties worldwide remains serious. In response to this challenge, the application of active safety systems in heavy commercial vehicles has become crucial in recent years. These systems can effectively reduce the likelihood of accidents and reduce the severity of accidents. Currently, active safety technologies such as anti-lock braking system (ABS), roll-over prevention (ROP), and electronic stability control system (ESC) have gradually become the core solution to improve vehicle stability and ensure driving safety.

[0003] The main goal of the electronic stability control system is to prevent the vehicle from sliding or losing control and ensure that the vehicle travels stably according to the driver's intention. In order to further enhance the handling of the vehicle, the direct yaw moment control (DYC) generates additional yaw moment by distributing the longitudinal braking force or driving force, thereby reducing the risk of skidding and fishtailing and maintaining the stability of the vehicle. For example, patent US7978729B2 discloses a vehicle dynamic control system that improves the stability of the vehicle by controlling the lateral acceleration and yaw rate of the vehicle.

[0004] However, the yaw control system is more commonly applied to passenger cars, and its application in heavy commercial vehicles faces special technical challenges. Heavy commercial vehicles have significant load variations and use pneumatic braking systems, which result in unique response delays and control complexities. Due to significant load variations, the longitudinal force distribution of the vehicle may be uneven, affecting the accurate control of the yaw moment. While pneumatic braking systems are widely used in heavy commercial vehicles, they have a slow response speed, and especially during emergency braking or rapid steering, the delay in braking can cause the vehicle to fail to generate the required yaw moment in time, thereby increasing the risk of skidding and loss of control. For example, patent EP2394577A1 relates to a method and system for improving vehicle braking performance by optimizing brake pressure regulation to reduce braking delay.

[0005] Existing yaw control strategies mainly rely on simulation research, lack comprehensive verification for actual complex working conditions, and most do not consider the impact of brake system delay on control effect. Therefore, it is particularly important to introduce a delay compensation mechanism in heavy commercial vehicles to overcome the hysteresis effect of pneumatic braking systems during braking. This compensation mechanism can further improve the yaw stability and control performance of heavy commercial vehicles in complex driving conditions, thereby having broad application prospects in dealing with the variable load and complex road conditions of heavy commercial vehicles.

[0006] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art. SUMMARY

[0007] In view of the above problems of the prior art, the present application aims to provide a heavy commercial vehicle yaw control system and method with delay compensation and slip suppression, so as to solve the problem that the yaw control performance is seriously degraded and the vehicle stability control performance cannot be met due to the factors that the vehicle load changes greatly and the aerodynamic braking system responds slowly in the prior art.

[0008] To achieve the above-mentioned purpose, the present application provides a heavy commercial vehicle yaw control system with delay compensation and slip suppression, comprising a state sensing unit, a yaw control unit and a braking force control unit.

[0009] The state sensing unit is used to collect various data related to the vehicle state during vehicle operation, and provides the required key information for the yaw control unit and the braking force control unit; the unit comprises a wheel integrated sensing module, a vehicle body state sensing module and a state parameter estimation module.

[0010] The wheel integrated sensing module is installed on each wheel to collect the wheel speed and the tire pressure;

[0011] The vehicle body state sensing module collects the vehicle dynamics state signal and the steering wheel angle signal;

[0012] The state parameter estimation module is used to filter various state data collected by the above-mentioned sensing modules, and estimate the related state quantities, and send them to the yaw control unit and the braking force control unit;

[0013] The yaw control unit is used to obtain the desired yaw moment required to realize the vehicle stability, and the desired braking moment required to prevent the wheel slip, and send them to the braking force control unit. It comprises a yaw angular velocity tracking module and a wheel slip suppression module.

[0014] The yaw angular velocity tracking module is used to calculate the desired yaw angular velocity according to the state data provided by the state sensing unit, and obtain the desired yaw moment required for the vehicle actual yaw angular velocity to track the desired yaw angular velocity through tracking control, so as to ensure the stability of the vehicle during normal driving;

[0015] The wheel slip suppression module is used to obtain the desired braking moment of each wheel required for the slip ratio to track the desired slip ratio through tracking control according to the state data provided by the state sensing unit and the desired slip ratio of each wheel known in advance, so as to avoid the occurrence of wheel slip phenomenon during braking of the vehicle.

[0016] The brake force control unit is used to solve the brake force control problem under the requirements of satisfying the yaw moment control and wheel slip suppression, and to solve the response delay problem of the pneumatic brake system of the commercial vehicle. It comprises a brake force cooperative distribution module and a brake force delay compensation module.

[0017] The brake force cooperative distribution module is used to coordinate the brake force distribution among the wheels according to the expected yaw moment obtained by the yaw rate tracking module and the expected brake moment of each wheel obtained by the wheel slip suppression module, and to calculate the expected brake chamber pressure of each wheel.

[0018] The brake force delay compensation module is used to calculate the predicted brake chamber pressure through a prediction model, to calculate the deviation from the expected brake chamber pressure of each wheel obtained by the brake force cooperative distribution module, and finally to obtain the control input of the brake actuator through a PID controller.

[0019] Preferably, in the above technical solution, the vehicle body state sensing module comprises a yaw rate sensor, a roll rate sensor, an acceleration sensor, a speed sensor and a steering wheel steering angle sensor; the state data obtained by the state parameter estimation module comprises acceleration, wheel speed, steering wheel angle, yaw rate and roll rate; and the estimated state quantities comprise vehicle speed, wheel slip rate, tire normal force and wheel brake force.

[0020] A heavy commercial vehicle yaw control method with delay compensation and slip suppression, based on the above system, the steps are as follows:

[0021] 1) Establish a nominal system model; based on the collected state parameters and vehicle dynamics characteristics, establish a nominal system model of the vehicle; the nominal system model is used to calculate the vehicle state parameters and generate the expected state to ensure the vehicle handling and stability under complex working conditions;

[0022] 2) Calculate the vehicle state parameters; based on the nominal system model, the vehicle acceleration, wheel speed, steering wheel angle, yaw rate, roll rate, vehicle speed, wheel slip rate, tire normal force and wheel brake force are calculated in real time to provide accurate state parameters as the basis for vehicle control;

[0023] 3) Yaw rate control; based on the nominal system model, the required yaw moment is calculated in real time by using the sliding mode control method to offset the external disturbance of the vehicle during sharp turning or emergency braking; this control algorithm uses sliding mode control technology to ensure that the yaw control still maintains high robustness when the vehicle working condition changes;

[0024] 4) Wheel slip suppression control; real-time monitoring of the slip ratio of each wheel through the wheel slip suppression module; adjusting the brake force distribution of each wheel using the slip suppression control algorithm;

[0025] 5) Brake force cooperative distribution. Coordinate the yaw rate control and the wheel slip suppression control, recalculate the expected brake force of each wheel required to meet the yaw stability and prevent the wheel slip of the vehicle, and calculate the expected brake chamber pressure to achieve a reasonable distribution of brake force among the wheels;

[0026] 6) Brake force delay compensation control. Due to the response lag problem of the pneumatic brake system of heavy commercial vehicles, a prediction model is used to compensate for the brake delay. Before the brake operation, according to the dynamic state of the vehicle, the delay behavior of the brake system is predicted, and the brake force output is adjusted in advance, so as to improve the response speed and control accuracy of the vehicle.

[0027] Preferably, in the above technical solution, the system model established in step 1) includes:

[0028] 11) Nonlinear lateral and longitudinal vehicle model:

[0029]

[0030] Where M represents the total mass of the vehicle, I x and I z are the moments of inertia around the X and Z axes of the vehicle center of gravity, and I xz / I zx are the products of inertia of the X and Z axes; v x and v y represent the longitudinal and lateral velocities of the vehicle; the lateral stiffness of the front and rear wheels are C αf and C ar , δ f represents the front wheel steering angle, F b is the brake force, fl, fr, rl, and rr represent the left front, right front, left rear, and right rear wheels; ∈ f and ∈ r are the yaw angle errors of the front and rear axles, C ∈f and C ∈r are the proportional constants of the front and rear axles related to the vehicle roll angle; M s represents the mass of the vehicle suspension, g is the acceleration of gravity, L f and L r are the distances from the vehicle center of gravity to the front and rear axles, h s is the vertical distance from the suspension mass center to the yaw axis; K φ is the suspension roll stiffness coefficient, and C φ is the suspension roll damping coefficient. denotes the vehicle yaw rate, β the vehicle sideslip angle, φ the vehicle roll angle, F y is the lateral ground force;

[0031] 12) Wheel slip dynamics model:

[0032]

[0033]

[0034] R denotes the effective radius of the wheel, V x is the wheel center speed, ω w the wheel angular speed, I w is the wheel moment of inertia, and α w denotes the wheel angular acceleration; the bearing force on the wheel is F c , the vertical ground force is F z , and the braking torque is denoted by τ b ; α is the tire side slip angle, μ x is the estimate of the longitudinal friction coefficient in the tire model; the normal force denotes the tire-ground interaction force, which is calculated by considering the independent masses of the vehicle front and rear axles;

[0035] 13) Linear three-freedom vehicle steady-state model:

[0036]

[0037]

[0038] Θ1= -2(C αf + C αr ), Θ3= 2(C αf C ∈f + C αr C ∈r ),

[0039] Θ4= -2(C αf L f - C αr L r ), Θ6= 2(C αf L f C ∈f - C αr L r C ∈r ).

[0040] Preferably, in the above technical solution, in order to efficiently calculate the vehicle state parameters, step 2) assumes that the spring mass performs rolling motion around the longitudinal axis of the vehicle, and the rolling of the unsprung mass can be ignored, while the sprung and unsprung masses perform yaw motion around the vertical axis passing through a point on the roll axis, and the vehicle roll angle is small; the tire longitudinal force and lateral force in the combined slip are calculated by applying the magic tire formula; the accurate tire normal force is calculated by decoupling the two axles and considering the virtual mass on each axle.

[0041] Preferably, in the above technical solution, the specific steps of step 3) of yaw rate control include:

[0042] 31) By setting the time derivative of the state vector to zero through the linear three-degree-of-freedom reference dynamics model of step 22), the steady-state value as a function of speed and front wheel steering angle is obtained

[0043] χ ss (t)=-A(v x ) -1 bδ f (t),and the expected yaw rate

[0044]

[0045] 32) The yaw angular acceleration is obtained through the dynamics model equation in step 21) as follows:

[0046] 33) By using the actual yaw rate collected in step 1), the expected yaw rate obtained in step 31), and the yaw angular acceleration obtained in step 32), a sliding surface and its derivative

[0047] 34) By applying the power rate index approaching law, the yaw rate control input can be obtained as follows:

[0048]

[0049] The power rate index reaching law is a reaching strategy for the sliding mode control. By reasonably selecting the control gain K0, the power index parameter β0, and other control parameters δ0, γ0, and φ0, fast convergence, effective chattering suppression, and improved robustness of the system can be achieved. The K0 determines the reaching speed of the system, and a larger K0 can accelerate the reaching of the sliding mode surface but can increase the chattering. The value of β0 is within the range of 0<β0<0.5, and affects the convergence speed and the chattering suppression effect. A larger β0 can reduce the chattering but reduces the convergence speed, and a smaller β0 is opposite. By reasonably configuring these parameters, the power rate index reaching law can effectively cope with the external disturbance and the uncertainty of the system, and achieve fast and stable control effect. The specific mathematical expression of the power rate index reaching law is as follows:

[0050]

[0051] Preferably, in the above technical solution, the specific steps of the wheel slip suppression control in step 4) include:

[0052] 41) The wheel slip model established in step 21) is calculated by using the rotation speed of each wheel and the longitudinal speed of the vehicle collected in step 1) to obtain the slip rate of each wheel

[0053] 42) Knowing the expected slip rate of each wheel, a sliding surface corresponding to the wheel slip suppression control of each wheel is established according to the slip rate calculated in step 41)

[0054] S 2,ij (t)=λ ij (t)-λ ij,ref , and the derivative thereof

[0055] 43) By applying the power rate index reaching law, the wheel slip suppression control input, i.e., the expected braking torque of each wheel, can be obtained as follows:

[0056]

[0057] The power rate index reaching law is a reaching strategy for the sliding mode control. By reasonably selecting the control gain K0, the power index parameter β0, and other control parameters δ0, γ0, and φ0, fast convergence, effective chattering suppression, and improved robustness of the system can be achieved. The K0 determines the reaching speed of the system, and a larger K0 can accelerate the reaching of the sliding mode surface but can increase the chattering. The value of β0 is within the range of 0<β0<0.5, and affects the convergence speed and the chattering suppression effect. A larger β0 can reduce the chattering but reduces the convergence speed, and a smaller β0 is opposite. By reasonably configuring these parameters, the power rate index reaching law can effectively cope with the external disturbance and the uncertainty of the system, and achieve fast and stable control effect. The specific mathematical expression of the power rate index reaching law is as follows:

[0058]

[0059] Preferably, in the above technical solution, the specific steps of step 5) of cooperative distribution of braking force include:

[0060] 51) Calculate the required braking force of each wheel according to the expected braking torque of each wheel obtained in step 43):

[0061]

[0062] 52) Recalculate the required braking force of the front outer wheel according to the left turn or right turn of the vehicle;

[0063] 53) Calculate the required braking torque of the front outer wheel:

[0064] τ b，ij (t) = F b，ij (t)R ij -α w，ij (t)I w，ij ;

[0065] 54) Calculate the expected brake chamber pressure required by each wheel:

[0066]

[0067] Preferably, in the above technical solution, the specific steps of step 6) of brake force delay compensation control include:

[0068] 61) Establish a state prediction model as follows:

[0069]

[0070] 62) Calculate the predicted brake chamber pressure by the prediction model

[0071] 63) Input the predicted brake chamber pressure and the expected brake chamber pressure calculated in step 53) into the PID controller to obtain the brake chamber control input.

[0072] Preferably, in the above technical solution, the step 52) of calculating the required braking force of the front outer wheel includes:

[0073] 511) When the vehicle is turning left, reduce the braking force of the front outer wheel, i.e. the right front wheel, to generate a counterclockwise external yaw moment, and the braking force is calculated by the following formula:

[0074]

[0075] 512)When the vehicle makes a right turn, the braking force of the front outer wheel, i.e., the left front wheel, is reduced to generate a clockwise external yaw moment, and the braking force is calculated by the following formula:

[0076]

[0077] Compared with the prior art, the present application has the following beneficial effects:

[0078] The present application is directed to the problem that heavy commercial vehicles are prone to wheel slip under the combined condition of cornering and braking, which leads to loss of steering ability and even loss of vehicle stability, and proposes a direct yaw control method capable of inhibiting wheel slip, which coordinates yaw control and wheel slip ratio control to optimize braking force distribution, so as to ensure the stability of the vehicle in complex steering and braking scenarios and enhance the handling performance of the vehicle.

[0079] The yaw angular velocity control and wheel slip inhibition control of the present application both adopt slip film control technology and apply power speed index approaching law, which improves the approaching speed of the slip film surface and reduces the occurrence of chattering behavior through the design of control parameters, and can ensure the robustness to external disturbances and parameter uncertainties of the system.

[0080] The present application is directed to the problem that heavy commercial vehicles are prone to wheel slip under the combined condition of cornering and braking, which leads to loss of steering ability and even loss of vehicle stability, and proposes a direct yaw control method capable of inhibiting wheel slip, which coordinates yaw control and wheel slip ratio control to optimize braking force distribution, so as to ensure the stability of the vehicle in complex steering and braking scenarios and enhance the handling performance of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0081] Figure 1 The present application is directed to the problem that heavy commercial vehicles are prone to wheel slip under the combined condition of cornering and braking, which leads to loss of steering ability and even loss of vehicle stability, and proposes a direct yaw control method capable of inhibiting wheel slip, which coordinates yaw control and wheel slip ratio control to optimize braking force distribution, so as to ensure the stability of the vehicle in complex steering and braking scenarios and enhance the handling performance of the vehicle.

[0082] Figure 2 The present application is directed to the problem that heavy commercial vehicles are prone to wheel slip under the combined condition of cornering and braking, which leads to loss of steering ability and even loss of vehicle stability, and proposes a direct yaw control method capable of inhibiting wheel slip, which coordinates yaw control and wheel slip ratio control to optimize braking force distribution, so as to ensure the stability of the vehicle in complex steering and braking scenarios and enhance the handling performance of the vehicle. DETAILED DESCRIPTION

[0083] The specific embodiments of the present application are described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0084] Unless otherwise explicitly stated, throughout the specification and claims, the term "comprise" or its variants such as "comprises" or "comprising" will be understood to encompass the stated element or components, but not to exclude the presence of other elements or components.

[0085] Example 1

[0086] The present application is directed to the problem that heavy commercial vehicles are prone to wheel slip under the combined condition of cornering and braking, which leads to loss of steering ability and even loss of vehicle stability, and proposes a direct yaw control method capable of inhibiting wheel slip, which coordinates yaw control and wheel slip ratio control to optimize braking force distribution, so as to ensure the stability of the vehicle in complex steering and braking scenarios and enhance the handling performance of the vehicle.

[0087] The state sensing unit is used to collect various data related to the state of the vehicle during operation, and to provide the required key information for the yaw control unit and the brake force control unit. The unit includes: a wheel integrated sensing module, a vehicle body state sensing module, and a state parameter estimation module;

[0088] The wheel integrated sensing module is used to be installed on each wheel to collect the wheel speed and tire pressure;

[0089] The vehicle body state sensing module is used to collect vehicle dynamics state signals and steering wheel angle signals;

[0090] The state parameter estimation module is used to filter various state data collected by the above-mentioned sensing modules, estimate relevant state quantities, and send them to the yaw control unit and the brake force control unit;

[0091] The yaw control unit is used to obtain the desired yaw moment required to achieve vehicle stability, and the desired brake moment required to prevent wheel slip, and send them to the brake force control unit. It includes: a yaw angular velocity tracking module and a wheel slip suppression module;

[0092] The yaw angular velocity tracking module is used to calculate the desired yaw angular velocity based on the state data provided by the state sensing unit, and to obtain the desired yaw moment required to track the actual yaw angular velocity of the vehicle to the desired yaw angular velocity through tracking control, to ensure the stability of the vehicle during normal driving;

[0093] The wheel slip suppression module is used to obtain the desired brake moment of each wheel required to track the desired slip ratio to the slip ratio through tracking control based on the state data provided by the state sensing unit and the desired slip ratio of each wheel known in advance, to avoid the occurrence of wheel slip during braking of the vehicle;

[0094] The brake force control unit is used to solve the brake force control problem under the requirements of yaw moment control and wheel slip suppression, and to solve the response delay problem of the pneumatic brake system of commercial vehicles. It includes: a brake force cooperative distribution module and a brake force delay compensation module;

[0095] The brake force cooperative distribution module is used to coordinate the brake force distribution among the wheels based on the desired yaw moment obtained by the yaw angular velocity tracking module and the desired brake moment of each wheel obtained by the wheel slip suppression module, to calculate the desired brake chamber pressure of each wheel;

[0096] The brake force delay compensation module is used to calculate the predicted brake chamber pressure through a prediction model, and to calculate the deviation of the predicted brake chamber pressure from the desired brake chamber pressure of each wheel obtained by the brake force cooperative distribution module, and finally to obtain the control input of the brake actuator through a PID controller;

[0097] Further, the vehicle body state sensing module comprises a yaw rate sensor, a roll rate sensor, an acceleration sensor, a speed sensor and a steering wheel steering angle sensor.

[0098] Further, the state data obtained by the state parameter estimation module comprises acceleration, wheel speed, steering wheel steering angle, yaw rate and roll rate. The estimated state quantities comprise vehicle speed, wheel slip ratio, tire normal force and wheel braking force.

[0099] Embodiment 2

[0100] A heavy commercial vehicle yaw control method with delay compensation and slip suppression according to the present application, based on the above system, the steps are as follows:

[0101] 1) Establish a nominal system model. According to the collected state parameters and vehicle dynamics characteristics, a nominal system model of the vehicle is established. The nominal system model is used to calculate the vehicle state parameters and generate the expected state to ensure the vehicle handling and stability under complex working conditions;

[0102] 2) Calculate the vehicle state parameters. According to the nominal system model, the vehicle acceleration, wheel speed, steering wheel steering angle, yaw rate, roll rate, vehicle speed, wheel slip ratio, tire normal force and wheel braking force are calculated in real time, which provides accurate state parameters as the basis for vehicle control;

[0103] 3) Yaw rate control. Based on the nominal system model, the required yaw moment is calculated in real time by using the sliding mode control method to offset the external disturbance of the vehicle during sharp turning or emergency braking. The control algorithm uses sliding mode control technology to ensure that the yaw control remains highly robust when the vehicle operating conditions change;

[0104] 4) Wheel slip suppression control. Through the wheel slip suppression module, the slip ratio of each wheel is monitored in real time. By using the slip suppression control algorithm, the braking force distribution of each wheel is adjusted to prevent wheel slip during braking on low adhesion road surfaces (such as wet or icy road surfaces), thereby improving the vehicle's grip performance and driving safety;

[0105] 5) Braking force cooperative distribution. Coordinate the yaw rate control and wheel slip suppression control, recalculate the expected braking force of each wheel required by the vehicle to meet the yaw stability and prevent wheel slip, and calculate the expected brake chamber pressure to achieve reasonable distribution of braking force among the wheels;

[0106] 6) Brake force delay compensation control. Due to the response lag problem of the pneumatic brake system of heavy commercial vehicles, a prediction model is used to compensate for brake delay. Before brake operation, according to the dynamic state of the vehicle, the delay behavior of the brake system is predicted, and the brake force output is adjusted in advance, so as to improve the response speed and control accuracy of the vehicle;

[0107] Further, the system model established in step 1) comprises:

[0108] 11) Nonlinear lateral and longitudinal vehicle model:

[0109]

[0110]

[0111] where M represents the total mass of the vehicle, I x and I z are the moments of inertia around the X and Z axes of the vehicle center of gravity, and I xz / I zx are the products of inertia of the X and Z axes. v x and v y represent the longitudinal and lateral velocities of the vehicle. The lateral stiffness of the front and rear wheels are C αf and C αr , respectively, δ f represents the front wheel steering angle, F b is the brake force, fl, fr, rl, and rr represent the left front, right front, left rear, and right rear wheels, respectively. f andò r are the yaw angle errors of the front and rear axles, C òf and C òr are the proportional constants of the front and rear axles related to the vehicle roll angle. M s represents the mass of the vehicle suspension, g is the acceleration of gravity, L f and L r are the distances from the vehicle center of gravity to the front and rear axles, h s is the vertical distance from the suspension mass center to the yaw axis. K φ is the suspension roll stiffness coefficient, and C φ is the suspension roll damping coefficient. represents the vehicle yaw rate, β is the vehicle side slip angle, φ is the vehicle roll angle, and F y is the lateral ground force.

[0112] 12) Wheel slip dynamics model:

[0113]

[0114]

[0115] R is the effective radius of the wheel, V x is the wheel center speed, ω w is the wheel angular speed, I w is the wheel moment of inertia, and a w is the wheel angular acceleration. The bearing force on the wheel is F c , the force normal to the ground is F z , and the braking torque is represented by τ b . a is the tire side slip angle, μ x is the estimate of the longitudinal friction coefficient in the tire model. The normal force is the force between the tire and the ground, which is calculated by considering the independent masses of the front and rear axles of the vehicle.

[0116] 13) Linear three-degree-of-freedom vehicle steady-state model:

[0117]

[0118] θ3=2(C αf C ∈f +C αr +C ∈r ), Θ4=-2(C αf L f -C αr L r ), Θ6=2(C αf L f C ∈f -C αr L r C ∈r ).

[0119] Further, step 2) is to efficiently calculate the vehicle state parameters, assuming that the spring mass performs rolling motion around the longitudinal axis of the vehicle, and the rolling of the unsprung mass can be ignored, while the sprung and unsprung masses perform yaw motion around the vertical axis passing through a certain point on the roll axis, and the vehicle roll angle is small; the tire longitudinal force and lateral force in the combined slip are calculated by applying the magic tire formula; the accurate tire normal force is calculated by decoupling the two axles and considering the virtual mass on each axle;

[0120] Further, the specific steps of step 3) of yaw rate control include:

[0121] 31) By setting the time derivative of the state vector to zero through the linear three-degree-of-freedom reference dynamics model of step 22), the steady-state value x ss (t)=-A(v x ) -1 bδf (t), and the expected yaw rate

[0122] 32) The yaw angular acceleration is obtained by the dynamic model equation in step 21) as follows:

[0123]

[0124]

[0125] 33) The slip surface is established by the actual yaw rate collected in step 1), the expected yaw rate obtained in step 31) and the yaw angular acceleration obtained in step 32) as follows: and its derivative

[0126] 34) The yaw rate control input is obtained by applying the power rate index approaching law as follows:

[0127]

[0128] Further, the specific steps of the wheel slip suppression control in step 4) include:

[0129] 41) The slip ratio of each wheel is calculated by the wheel slip model established in step 21) and the rotational speed of each wheel and the longitudinal speed of the vehicle collected in step 1)

[0130] 42) The slip surface s corresponding to the wheel slip suppression control of each wheel is established according to the slip ratio calculated in step 41) and the expected slip ratio of each wheel 2,ij (t) = λ ij (t) - λ ij,ref and its derivative

[0131] 43) The wheel slip suppression control input, i.e. the expected braking torque of each wheel, is obtained by applying the power rate index approaching law as follows:

[0132]

[0133] Further, the specific steps of the braking force cooperative distribution in step 5) include:

[0134] 51) The required braking force of each wheel is calculated according to the expected braking torque of each wheel obtained in step 43)

[0135]

[0136] 52) The required braking force of the front outer wheel is recalculated according to the left turn or right turn of the vehicle;

[0137] 53) Calculate the required braking torque of the front outer wheel:

[0138] τ b，ij (t) = F b，ij (t)R ij - a W，ij (t)I w,ij ;

[0139] 54) Calculate the required expected brake chamber pressure of each wheel:

[0140]

[0141] Further, the specific steps of the brake force delay compensation control in step 6) include:

[0142] 61) Establish a state prediction model as follows:

[0143]

[0144] 62) Calculate the predicted brake chamber pressure by the prediction model

[0145] 63) Input the predicted brake chamber pressure and the expected brake chamber pressure calculated in step 53) into the PID controller to obtain the brake chamber control input;

[0146] Further, the judgment in step 52) for calculating the required braking force of the front outer wheel includes:

[0147] 511) When the vehicle is turning left, reduce the braking force of the front outer wheel, i.e. the right front wheel, to generate a counterclockwise external yaw moment, and the braking force is calculated by the following formula:

[0148]

[0149] 512) When the vehicle is turning right, reduce the braking force of the front outer wheel, i.e. the left front wheel, to generate a clockwise external yaw moment, and the braking force is calculated by the following formula:

[0150]

[0151] Further, the power rate index approaching law applied in the steps 34) and 43) is an approaching strategy for the sliding mode control. By reasonably selecting the control gain K0, the power index parameter β0 and other control parameters δ0, γ0 and φ0, fast convergence, effective chattering suppression and improved robustness of the system can be achieved. Among them, K0 determines the reaching speed of the system, and larger K0 can speed up the reaching of the sliding mode surface, but may increase the chattering. The value of β0 is in the range of 0<β0<0.5, which affects the convergence speed and chattering suppression effect. Larger β0 can reduce chattering, but reduces the convergence speed, while smaller β0 is the opposite. By reasonably configuring these parameters, the power rate index approaching law can effectively cope with external disturbances and uncertainties of the system, and achieve fast and stable control effect. The specific mathematical expression of the power rate index approaching law is as follows:

[0152]

[0153] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings without departing from the spirit or essential characteristics of the present application. The exemplary embodiments are chosen and described in order to explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims and their equivalents.

Claims

1. A heavy commercial vehicle yaw control system with delay compensation and slip suppression, characterized in that: Comprising: a state sensing unit, a yaw control unit and a brake force control unit; the state sensing unit is used to collect various data related to the state of the vehicle during operation, providing the required key information for the yaw control unit and the brake force control unit; the unit includes: wheel integrated sensing module, vehicle body state sensing module and state parameter estimation module; the wheel integrated sensing module is installed on each wheel to collect wheel speed and tire pressure; the vehicle body state sensing module collects vehicle dynamics state signals and steering wheel angle signals; the state parameter estimation module is used to filter various state data collected by the above sensing modules and estimate relevant state quantities, and send them to the yaw control unit and the brake force control unit; the yaw control unit is used to obtain the desired yaw moment required to achieve vehicle stability and the desired brake moment required to prevent wheel slip, and send it to the brake force control unit; including: yaw rate tracking module, wheel slip suppression module; the yaw rate tracking module is used to calculate the desired yaw rate according to the state data provided by the state sensing unit, and to obtain the desired yaw moment required to track the actual yaw rate of the vehicle to the desired yaw rate through tracking control, to ensure the stability of the vehicle during normal driving; the wheel slip suppression module is used to obtain the desired brake moment of each wheel required to track the desired slip ratio to the slip ratio through tracking control according to the state data provided by the state sensing unit and the desired slip ratio of each wheel known in advance, to avoid the occurrence of wheel slip during braking of the vehicle; the brake force control unit is used to solve the brake force control problem under the requirements of yaw moment control and wheel slip suppression, and to solve the response delay problem of the pneumatic brake system of the commercial vehicle; including: brake force cooperative distribution module, brake force delay compensation module; the brake force cooperative distribution module is used to coordinate the distribution of brake force among the wheels according to the desired yaw moment obtained by the yaw rate tracking module and the desired brake moment of each wheel obtained by the wheel slip suppression module, to calculate the desired brake chamber pressure of each wheel; the brake force delay compensation module is used to calculate the predicted brake chamber pressure through a prediction model, and to calculate the deviation of the predicted brake chamber pressure from the desired brake chamber pressure of each wheel obtained by the brake force cooperative distribution module, and finally to obtain the control input of the brake actuator through a PID controller.

2. Heavy commercial vehicle yaw control system with delay compensation and slip suppression according to claim 1, characterized in that The vehicle body state sensing module includes: yaw rate sensor, roll rate sensor, acceleration sensor, speed sensor and steering wheel steering angle sensor; the state data obtained by the state parameter estimation module includes: acceleration, wheel speed, steering wheel angle, yaw rate, roll rate; the estimated state quantities include: vehicle speed, wheel slip ratio, tire normal force, wheel brake force.

3. A heavy commercial vehicle yaw control method with delay compensation and slip suppression based on the system of claim 1 or 2, the steps are as follows: 1) Establishing a nominal system model; a nominal system model of the vehicle is established according to the collected state parameters and the vehicle dynamics characteristics; the nominal system model is used to calculate the vehicle state parameters and generate the expected state under complex working conditions to ensure the vehicle handling and stability; 2) Calculating the vehicle state parameters; According to the nominal system model, the vehicle acceleration, wheel speed, steering wheel angle, yaw rate, roll rate, vehicle speed, wheel slip rate, tire normal force, and wheel braking force are calculated in real time to provide accurate state parameters as the basis for vehicle control; 3) Yaw rate control; based on the nominal system model, the required yaw moment is calculated in real time using the sliding mode control method to offset external disturbances when the vehicle is turning sharply or braking urgently; the control algorithm uses sliding mode control technology to ensure that the yaw control remains highly robust when the vehicle's working conditions change; 4) Wheel slip suppression control; the wheel slip suppression module monitors the slip rate of each wheel in real time; the slip suppression control algorithm adjusts the braking force distribution of each wheel; 5) Brake force collaborative distribution; the yaw rate control and wheel slip suppression control are coordinated to recalculate the expected braking force of each wheel required by the vehicle to meet the yaw stability and prevent wheel slip, and to calculate the expected brake chamber pressure to achieve reasonable distribution of braking force between the wheels; 6) Brake force delay compensation control; due to the response lag of the pneumatic braking system of heavy commercial vehicles, a prediction model is used to compensate for the braking delay; before braking, the delay behavior of the braking system is predicted based on the dynamic state of the vehicle, and the braking force output is adjusted in advance to improve the response speed and control accuracy of the vehicle.

4. Heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 3, characterized in that The system model established in step 1) includes: 11) Nonlinear lateral-longitudinal-vertical vehicle model: where, represents the total mass of the vehicle, and are the moments of inertia about the vehicle's center of gravity axis and axis, respectively, while is the product of inertia of axis and axis; and denote the longitudinal and lateral velocities of the vehicle, respectively; the cornering stiffness of the front and rear wheels are and , denotes the front wheel steering angle, is the braking force, , , , denote the left front, right front, left rear and right rear wheels, respectively; and are the yaw angle errors of the front and rear axles, and are the proportional constants of the front and rear axles related to the vehicle roll angle; denotes the suspension mass of the vehicle, is the gravitational acceleration, and are the distances of the front and rear axles from the vehicle's center of gravity, is the vertical distance of the suspension mass center to the yaw axis; is the suspension roll stiffness coefficient, is the suspension roll damping coefficient; denotes the vehicle yaw rate, is the vehicle sideslip angle, is the vehicle roll angle, is the lateral ground force; 12) Wheel slip dynamics model: , denotes the effective radius of the wheel, is the wheel center velocity, is the wheel angular velocity, is the wheel moment of inertia, and denotes the wheel angular acceleration; the bearing force on the wheel is , the vertical ground force is , and the braking torque is denoted by is the tire side slip angle, is the estimate of the longitudinal friction coefficient in the tire model; the normal force denotes the tire ground interaction force, which is calculated by considering the independent masses of the front and rear axles;​ 13) Linear three-freedom vehicle steady-state model: 。 5. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 3, characterized in that: To efficiently calculate the vehicle state parameters, step 2) assumes that the spring mass rolls around the vehicle's longitudinal axis, while the roll of the unsprung mass can be ignored, and that the sprung and unsprung masses roll around a vertical axis passing through a certain point on the roll axis, with a small vehicle roll angle; the tire longitudinal and lateral forces in the combined slip are calculated by applying the magic tire formula; the accurate tire normal force is calculated by decoupling the two axles and considering the virtual mass on each axle.

6. The heavy commercial vehicle yaw control method with delay compensation and slip suppression of claim 3, characterized by: The specific steps of the yaw rate control in step 3) include: 31) By setting the time derivative of the state vector to zero through the linear three-DOF reference dynamics model of step 22), the steady-state values are obtained as a function of the speed and front-wheel steering angle and the desired yaw rate is calculated as ​ 32) The yaw angular acceleration is obtained through the dynamic model equation in step 21) as follows: ； 33) Establish a slip surface by the actual yaw rate collected in step 1), the desired yaw rate obtained in step 31) and the yaw angular acceleration obtained in step 32) , and the derivative thereof; 34) By applying the power speed index approaching law, the yaw rate control input can be obtained as follows: ; the power exponent approaching law is an approaching strategy for sliding mode control; by reasonably selecting the control gain , the power exponent parameter and other control parameters , and , fast convergence, effective chattering suppression and improved robustness of the system can be achieved; wherein, determines the reaching speed of the system, a larger can accelerate the reaching of the sliding surface, but may increase chattering; has a value in the range of , affecting the convergence speed and chattering suppression effect, a larger can reduce chattering, but reduces the convergence speed, while a smaller is the opposite; by reasonably configuring these parameters, the power exponent approaching law can effectively deal with external disturbances and system uncertainties, achieving fast and stable control effect; the specific mathematical expression of the power exponent approaching law is as follows: 。 7. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 3, characterized in that: The specific steps of the wheel slip suppression control in step 4) include: 41) The wheel slip model established in step 21) is used to calculate the slip rate of each wheel using the wheel speed and vehicle longitudinal speed collected in step 1); 42) The slip surface corresponding to the slip suppression control of each wheel is established based on the slip ratio calculated in step 41), given the desired slip ratio of each wheel and the derivative ; 43) By applying the power rate index reaching law, the wheel slip suppression control input, i.e., the expected braking torque of each wheel, can be obtained as follows: The power rate index reaching law is a reaching strategy for the sliding mode control. By reasonably selecting the control gain , the power index parameter , and other control parameters , and , fast convergence, effective chattering suppression, and improved robustness of the system can be achieved. Among them, determines the reaching speed of the system. A larger can speed up the reaching of the sliding surface, but may increase chattering; The value of is in the range of , which affects the convergence speed and chattering suppression effect. A larger can reduce chattering, but reduces the convergence speed, while a smaller is the opposite. By reasonably configuring these parameters, the power rate index reaching law can effectively deal with external disturbances and system uncertainties, achieving fast and stable control effect. The specific mathematical expression of the power rate index reaching law is as follows: .

8. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 3, characterized in that: The specific steps of the brake force collaborative distribution in step 5) include: 51) calculating the braking force required for each wheel from the braking torque expected for each wheel obtained in step 43) : ; 52) According to the vehicle turning left or right, the required braking force of the front outer wheel is recalculated; 53) calculating the braking torque required for the front outer wheel: ; 54) calculating the desired brake chamber pressure required for each wheel: .

9. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 3, characterized in that: The specific steps of the brake force delay compensation control in step 6) include: 61) The state prediction model is established as follows: ; 62) calculating a predicted brake chamber pressure by a prediction model ; 63) inputting the predicted brake chamber pressure and the desired brake chamber pressure calculated in step 53) into a PID controller to obtain a brake chamber control input.

10. The heavy commercial vehicle yaw control method with delay compensation and slip suppression of claim 8, characterized by: The step 52) of calculating the braking force required by the front outer wheel includes: 511) When the vehicle makes a left turn, the braking force of the front outer wheel, i.e. the right front wheel, is reduced to generate a counterclockwise outer yaw moment, and the braking force thereof is calculated by the following equation: ; 512)When the vehicle is making a right turn, the braking force of the front outer wheel, i.e. the left front wheel, is reduced to generate a clockwise outer yaw moment, and the braking force is calculated by the following equation: .

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