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

Abstract

The invention 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 braking force control unit. The yaw control unit acquires a desired yaw moment and a braking moment. A yaw velocity tracking module calculates a desired yaw velocity. And the wheel slip suppression module obtains a brake torque for avoiding slip through control. The braking force control unit addresses braking force distribution under yaw moment control and wheel slip suppression, and compensates for the delay of the pneumatic brake system. And the braking force cooperative distribution module calculates the expected braking chamber pressure of each wheel according to the required yawing moment and the braking moment. The braking force delay compensation module calculates and predicts the pressure of a braking chamber through a prediction model, and obtains control input of a braking actuator through a PID controller so as to compensate delay. According to the system, the driving safety of the heavy commercial vehicle under the complex road condition is improved through cooperative control.

Description

Technical Field

[0001] The present invention belongs to the technical field of commercial vehicle driving and control, and in particular relates to a heavy commercial vehicle yaw control system and method with delay compensation and slip suppression. Background Art

[0002] As the number of motor vehicles continues to increase, the global road accidents and related casualties remain a serious problem. To meet this challenge, the application of active safety systems in heavy commercial vehicles has become crucial in recent years. These systems can effectively reduce the possibility of accidents and reduce the severity of accidents. Currently, active safety technologies such as anti-lock braking systems (ABS), rollover prevention systems (ROP) and electronic stability control systems (ESC) have gradually become the core solutions for improving vehicle stability and ensuring driving safety.

[0003] The main goal of the electronic stability control system is to prevent the vehicle from skidding or losing control and to ensure that the vehicle drives stably as the driver intends. In order to further enhance the vehicle's handling, 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 tail swinging 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, yaw control systems are more commonly used in passenger cars, while their application in heavy commercial vehicles faces special technical challenges. Heavy commercial vehicles have significant load variations and use pneumatic braking systems, which lead to unique response delays and control complexity. Due to significant load variations, the longitudinal force distribution of the vehicle may be uneven, thus affecting the precise control of the yaw moment. Although pneumatic braking systems are widely used in heavy commercial vehicles, their response speed is slow. Especially during emergency braking or rapid steering, braking delays can cause the vehicle to be unable to generate the required yaw moment in time, thereby causing the risk of skidding and loss of control. For example, patent EP2394577A1 relates to a method and system for improving vehicle braking performance by reducing braking delays by optimizing brake pressure regulation.

[0005] Existing yaw control strategies mainly rely on simulation research, lack comprehensive verification for actual complex working conditions, and most of them 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-duty commercial vehicles to overcome the hysteresis effect of the pneumatic brake system during braking. This compensation mechanism can further improve the yaw stability and control performance of heavy-duty commercial vehicles under complex driving conditions, and thus has broad application prospects when dealing with variable loads and complex road conditions of heavy-duty commercial vehicles.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a heavy-duty commercial vehicle yaw control system and method with delay compensation and slip suppression, so as to solve the problem that the prior art does not take into account the factors of large vehicle load changes and slow response of the pneumatic braking system, resulting in serious degradation of yaw control performance and failure to meet vehicle stability control performance.

[0008] To achieve the above object, the present invention 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 about the vehicle state during operation and provide the yaw control unit and the braking force control unit with the required key information; the unit includes: an integrated wheel sensing module, a vehicle state sensing module and a state parameter estimation module;

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

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

[0012] A state parameter estimation module is used to filter various state data collected by the above-mentioned sensor module, estimate relevant state quantities, and package 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 torque required to achieve vehicle stability and the desired braking torque required to prevent wheel slip, and send them to the braking force control unit. It includes: yaw angular velocity tracking module, wheel slip suppression module;

[0014] 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 obtain the desired yaw moment required for the actual yaw rate of the vehicle to track the desired yaw rate 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 expected braking torque of each wheel required for tracking the expected slip rate through tracking control according to the state data provided by the state sensing unit and the expected slip rate of each wheel known in advance, so as to avoid the occurrence of wheel slip during the braking process of the vehicle;

[0016] The braking force control unit is used to solve the problem of braking force control under the requirements of yaw moment control and wheel slip suppression, and solve the response delay problem of commercial vehicle pneumatic braking system. It includes: braking force collaborative distribution module, braking force delay compensation module;

[0017] A braking force coordination distribution module is used to coordinate the braking force distribution between the wheels and calculate the expected brake chamber pressure of each wheel according to the expected yaw moment obtained by the yaw angular velocity tracking module and the expected braking moment of each wheel obtained by the wheel slip suppression module;

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

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

[0020] A yaw control method for a heavy commercial vehicle with delay compensation and slip suppression, based on the above system, comprises the following steps:

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

[0022] 2) Calculate vehicle state parameters: Based on the nominal system model, calculate in real time the vehicle acceleration, wheel speed, steering wheel angle, yaw rate, roll rate, vehicle speed, wheel slip rate, tire normal force, and wheel braking force, providing accurate state parameters as a basis for vehicle control;

[0023] 3) Yaw rate control: Based on the nominal system model, the sliding mode control method is used to calculate the required yaw torque in real time to offset the external interference when the vehicle is turning sharply or braking urgently. The control algorithm uses sliding mode control technology to ensure that the yaw control can still maintain high robustness when the vehicle operating conditions change.

[0024] 4) Wheel slip suppression control: The wheel slip suppression module monitors the slip rate of each wheel in real time; the wheel slip suppression control algorithm is used to adjust the braking force distribution of each wheel;

[0025] 5) Coordinated distribution of braking force. Coordinate yaw rate control and wheel slip suppression control, recalculate the expected braking force of each wheel required to simultaneously meet yaw stability and prevent wheel slip, and calculate the expected brake chamber pressure to achieve reasonable distribution of braking force between each wheel;

[0026] 6) Braking force delay compensation control. Since the pneumatic brake system of heavy commercial vehicles has a response lag problem, a prediction model is used to compensate for the braking delay. Before the braking operation, the delay behavior of the braking system is predicted according to the dynamic state of the vehicle, and the braking force output is adjusted in advance, thereby improving the vehicle's response speed and control accuracy.

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

[0028] 11) Nonlinear lateral, longitudinal and vertical 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 vehicle's center of gravity, X-axis and Z-axis, respectively, and I xz / I zx is the inertia product of the X-axis and the Z-axis; v x and v y They represent the longitudinal speed and lateral speed of the vehicle respectively; the cornering stiffness of the front and rear wheels are C αf and C ar , δ f Indicates the front wheel steering angle, F b is the braking force, fl, fr, rl, rr represent the left front, right front, left rear and right rear wheels respectively; ∈ f and ∈ r is the yaw angle error of the front and rear axles, C ∈f and C ∈r M is the proportional constant of the front and rear axles related to the vehicle roll angle; s represents the mass of the vehicle suspension, g is the acceleration due to gravity, L f and L r are the distances from the front and rear wheels to the vehicle's center of gravity, h s is the vertical distance from the center of mass of the suspension to the yaw axis; K φ is the suspension roll stiffness coefficient, C φ is the suspension roll damping coefficient. represents the vehicle yaw rate, β is the vehicle sideslip angle, φ is the vehicle roll angle, and F y is the lateral ground force;

[0031] 12) Wheel slip dynamics model:

[0032]

[0033]

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

[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 step 2), in order to efficiently calculate the vehicle state parameters, it is assumed that the spring mass rolls around the longitudinal axis of the vehicle, while the rolling of the unsprung mass can be ignored, and at the same time, the sprung and unsprung masses yaw around a vertical axis passing through a point on the roll axis, and it is assumed that 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; and 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 yaw angular velocity control in step 3) include:

[0042] 31) By using the linear three-degree-of-freedom reference dynamic model of step 22), the time derivative of the state vector is set to zero, and 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 calculate the expected yaw rate

[0044]

[0045] 32) Through the dynamic model equation in step 21), the yaw angular acceleration is obtained as follows:

[0046] 33) Establish the sliding membrane surface by using the actual yaw rate collected in step 1), the expected yaw rate obtained in step 31) and the yaw acceleration obtained in step 32). and its derivative

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

[0048]

[0049] The power-speed exponential reaching law is a reaching strategy for sliding mode control. By properly selecting the control gain K0, the power parameter β0, and other control parameters δ0, γ0, and φ0, rapid convergence, effective suppression of chattering, and improved system robustness can be achieved. Among them, K0 determines the arrival speed of the system. A larger K0 can speed up the arrival of the sliding surface, but may increase chattering. The value of β0 is in the range of 0<β0<0.5, which affects the convergence speed and chattering suppression effect. A larger β0 can reduce chattering, but reduce the convergence speed, while a smaller β0 has the opposite effect. By properly configuring these parameters, the power-speed exponential reaching law can effectively cope with external disturbances and system uncertainties, and achieve fast and stable control effects. The specific mathematical expression of the power-speed exponential 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) calculates the slip rate of each wheel using the rotation speed of each wheel and the longitudinal speed of the vehicle collected in step 1)

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

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

[0055] 43) By applying the power-speed exponential approach law, the wheel slip suppression control input, i.e., the desired braking torque of each wheel, can be obtained as follows:

[0056]

[0057] The power-rate exponential reaching law is a reaching strategy for sliding mode control. By properly selecting the control gain K0, the power parameter β0 and other control parameters δ0, γ0 and φ0, fast convergence, effective chattering suppression and improved system robustness can be achieved. Among them, K0 determines the arrival speed of the system. A larger K0 can speed up the arrival of the sliding surface, but may increase chattering. The value of β0 is in the range of 0<β0<0.5, which affects the convergence speed and chattering suppression effect. A larger β0 can reduce chattering but reduce the convergence speed, while a smaller β0 has the opposite effect. By properly configuring these parameters, the power-rate exponential reaching law can effectively cope with external disturbances and system uncertainties, and achieve fast and stable control effects. The specific mathematical expression of the power-rate exponential reaching law is as follows:

[0058]

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

[0060] 51) According to the desired braking torque of each wheel obtained in step 43), the braking force required by each wheel is calculated:

[0061]

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

[0063] 53) Calculate the braking torque required for 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 for each wheel:

[0066]

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

[0068] 61) The state prediction model is established as follows:

[0069]

[0070] 62) The predicted brake chamber pressure is calculated by the prediction model

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

[0072] Preferably, in the above technical solution, the step 52) calculates the braking force required by the front outer wheel and the determination includes:

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

[0074]

[0075] 512) When the vehicle turns right, 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 invention has the following beneficial effects:

[0078] In order to address the problem that heavy commercial vehicles are prone to wheel slippage, loss of steering ability and even loss of vehicle stability under combined turning and braking conditions, the present invention proposes a direct yaw control method that can suppress wheel slippage, coordinates yaw control and wheel slip rate control to optimize the distribution of braking force, and can ensure vehicle stability in complex steering and braking scenarios, thereby enhancing the vehicle's handling performance.

[0079] The yaw rate control and wheel slip suppression control of the present invention both adopt sliding film control technology and apply the power-speed exponential approach law. By designing control parameters, the approach speed of the sliding film surface is improved and the occurrence of jitter behavior is reduced, thereby ensuring robustness to external interference and parameter uncertainty of the system.

[0080] Aiming at the problems of easy oscillation of response delay and degradation of reference output regulation performance of pneumatic brakes of heavy commercial vehicles, the present invention introduces delay compensation technology into the designed PID feedback controller. By designing a state predictor to estimate the future state of the delay system, the transient response performance and control accuracy of the braking force control are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a structural diagram of the system of the present invention.

[0082] Figure 2 Flow chart of the method of the present invention. DETAILED DESCRIPTION

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

[0084] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0085] Example 1

[0086] A heavy commercial vehicle yaw control system with delay compensation and slip suppression of the present invention comprises: a state sensing unit, a yaw control unit, and a braking force control unit;

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

[0088] The wheel-integrated sensor module is installed on each wheel to collect wheel speed and tire pressure;

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

[0090] A state parameter estimation module is used to filter various state data collected by the above-mentioned sensor module, estimate relevant state quantities, and package and send them to the yaw control unit and the braking force control unit;

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

[0092] 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 obtain the desired yaw moment required for the actual yaw rate of the vehicle to track the desired yaw rate through tracking control, so as to ensure the stability of the vehicle during normal driving;

[0093] The wheel slip suppression module is used to obtain the expected braking torque of each wheel required for tracking the expected slip rate through tracking control according to the state data provided by the state sensing unit and the expected slip rate of each wheel known in advance, so as to avoid the occurrence of wheel slip during the braking process of the vehicle;

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

[0095] A braking force coordination distribution module is used to coordinate the braking force distribution between the wheels and calculate the expected brake chamber pressure of each wheel according to the expected yaw moment obtained by the yaw angular velocity tracking module and the expected braking moment of each wheel obtained by the wheel slip suppression module;

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

[0097] Further, the vehicle body state sensing module includes: a yaw angular velocity sensor, a roll angular velocity sensor, an acceleration sensor, a speed sensor and a steering wheel steering angle sensor;

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

[0099] Example 2

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

[0101] 1) Establish a nominal system model. Establish a nominal system model of the vehicle based on the collected state parameters and vehicle dynamics characteristics. The nominal system model is used to calculate the vehicle state parameters and generate the desired state to ensure vehicle controllability and stability under complex working conditions;

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

[0103] 3) Yaw rate control. Based on the nominal system model, the sliding mode control method is used to calculate the required yaw torque in real time to offset the external interference when the vehicle is turning sharply or braking urgently. The control algorithm uses sliding mode control technology to ensure that the yaw control can still maintain a high robustness when the vehicle operating conditions change;

[0104] 4) Wheel slippage suppression control. The wheel slippage suppression module monitors the slippage rate of each wheel in real time. The slippage suppression control algorithm adjusts the braking force distribution of each wheel to prevent the wheel from slipping when braking on low-adhesion roads (such as wet or icy roads), thereby improving the vehicle's grip and driving safety.

[0105] 5) Coordinated distribution of braking force. Coordinate yaw rate control and wheel slip suppression control, recalculate the expected braking force of each wheel required to simultaneously meet yaw stability and prevent wheel slip, and calculate the expected brake chamber pressure to achieve reasonable distribution of braking force between each wheel;

[0106] 6) Braking force delay compensation control. Since the pneumatic braking system of heavy commercial vehicles has a response lag problem, a prediction model is used to compensate for the braking delay. Before the braking operation, the delay behavior of the braking system is predicted according to the dynamic state of the vehicle, and the braking force output is adjusted in advance, thereby improving the vehicle's response speed and control accuracy;

[0107] Furthermore, the system model established in step 1) includes:

[0108] 11) Nonlinear lateral, longitudinal and vertical 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 vehicle's center of gravity, X-axis and Z-axis, respectively, and I xz / I zx is the product of inertia between the X-axis and the Z-axis. x and v y They represent the longitudinal speed and lateral speed of the vehicle respectively. The cornering stiffness of the front and rear wheels are C αf and C αr , δ f Indicates the front wheel steering angle, F b is the braking force, fl, fr, rl, rr represent the left front, right front, left rear, and right rear wheels respectively. f and r is the yaw angle error of the front and rear axles, C òf and C òr M is the proportional constant of the front and rear axles related to the vehicle roll angle. s represents the mass of the vehicle suspension, g is the acceleration due to gravity, L f and L r are the distances from the front and rear wheels to the vehicle's center of gravity, h s K is the vertical distance from the center of mass of the suspension to the yaw axis. φ is the suspension roll stiffness coefficient, C φ is the suspension roll damping coefficient. represents the vehicle yaw rate, β is the vehicle sideslip 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 represents the effective radius of the wheel, V x is the wheel center speed, ω w is the wheel angular velocity, I w is the moment of inertia of the wheel, and α w The bearing force on the wheel is F c , the force perpendicular to the ground is F z , braking torque is τ b α is the side slip angle of the tire, μ x is an estimate of the longitudinal friction coefficient in the tire model. Normal force It represents the force between the tire and the ground, calculated by considering the independent masses of the front and rear axles of the vehicle.

[0116] 13) Linear three-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] Furthermore, in order to efficiently calculate the vehicle state parameters, the step 2) assumes that the spring mass rolls around the longitudinal axis of the vehicle, and the rolling of the unsprung mass is negligible, and the sprung and unsprung masses yaw around a vertical axis passing through a point on the roll axis, and the vehicle roll angle is assumed to be 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] Furthermore, the specific steps of yaw angular velocity control in step 3) include:

[0121] 31) By using the linear three-degree-of-freedom reference dynamic model of step 22), the time derivative of the state vector is set to zero, and the steady-state value x as a function of speed and front wheel steering angle is obtained. ss (t) = -A(v x ) -1 bδf (t), and calculate the expected yaw rate

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

[0123]

[0124]

[0125] 33) Establish the sliding membrane surface by using the actual yaw rate collected in step 1), the expected yaw rate obtained in step 31) and the yaw acceleration obtained in step 32). and its derivative

[0126] 34) By applying the power rate exponential reaching law, the yaw rate control input can be obtained as follows:

[0127]

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

[0129] 41) The wheel slip model established in step 21) calculates the slip rate of each wheel using the rotation speed of each wheel and the longitudinal speed of the vehicle collected in step 1)

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

[0131] 43) By applying the power-speed exponential approach law, the wheel slip suppression control input, i.e., the desired braking torque of each wheel, can be obtained as follows:

[0132]

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

[0134] 51) According to the desired braking torque of each wheel obtained in step 43), the braking force required by each wheel is calculated:

[0135]

[0136] 52) Recalculate the braking force required by the front outer wheel according to whether the vehicle turns left or right;

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

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

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

[0140]

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

[0142] 61) The state prediction model is established as follows:

[0143]

[0144] 62) The predicted brake chamber pressure is calculated by the prediction model

[0145] 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;

[0146] Furthermore, the step 52) calculates the braking force required by the front outer wheel and makes a judgment including:

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

[0148]

[0149] 512) When the vehicle turns right, 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:

[0150]

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

[0152]

[0153] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A heavy commercial vehicle yaw control system with delay compensation and slip suppression, characterized in that: include: State sensing unit, yaw control unit and brake force control unit; The state sensing unit is used to collect various data about the vehicle state when the vehicle is running, and provide the yaw control unit and the braking force control unit with the required key information; the unit includes: an integrated wheel sensing module, a vehicle body state sensing module and a state parameter estimation module; The wheel-integrated sensor 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; A state parameter estimation module is used to filter various state data collected by the above-mentioned sensor module, estimate relevant state quantities, and package and send them to the yaw control unit and the braking force control unit; The yaw control unit is used to obtain the desired yaw moment required to achieve vehicle stability and the desired braking moment required to prevent wheel slip, and send them to the braking force control unit. It includes: a yaw angular velocity tracking module and a 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 obtain the desired yaw moment required for the actual yaw rate of the vehicle to track the desired yaw rate through tracking control, so as to ensure the stability of the vehicle during normal driving; The wheel slip suppression module is used to obtain the expected braking torque of each wheel required for tracking the expected slip rate through tracking control according to the state data provided by the state sensing unit and the expected slip rate of each wheel known in advance, so as to avoid the occurrence of wheel slip during the braking process of the vehicle; The braking force control unit is used to solve the problem of braking force control under the requirements of yaw moment control and wheel slip suppression, and solve the response delay problem of commercial vehicle pneumatic braking system. It includes: braking force collaborative distribution module, braking force delay compensation module; A braking force coordination distribution module is used to coordinate the braking force distribution between the wheels and calculate the expected brake chamber pressure of each wheel according to the expected yaw moment obtained by the yaw angular velocity tracking module and the expected braking moment of each wheel obtained by the wheel slip suppression module; The braking force delay compensation module is used to obtain the predicted brake chamber pressure through the prediction model, and calculate the deviation from the expected brake chamber pressure of each wheel obtained by the braking force coordinated distribution module, and finally obtain the control input of the brake actuator through the PID controller.

2. The 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: a yaw angular velocity sensor, a roll angular velocity sensor, an acceleration sensor, a speed sensor and a steering wheel steering angle sensor; the state data obtained by the state parameter estimation module includes acceleration, wheel speed, steering wheel angle, yaw angular velocity, and roll angular velocity; the estimated state quantities include vehicle speed, wheel slip rate, tire normal force, and wheel braking force.

3. A yaw control method for a heavy commercial vehicle with delay compensation and slip suppression, based on the above system, the steps are as follows: 1) Establish a nominal system model; establish a nominal system model of the vehicle based on the collected state parameters and vehicle dynamics characteristics; the nominal system model is used to calculate the vehicle state parameters and generate the desired state to ensure vehicle controllability and stability under complex working conditions; 2) Calculate 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 a basis for vehicle control; 3) Yaw rate control: Based on the nominal system model, the sliding mode control method is used to calculate the required yaw torque in real time to offset the external interference when the vehicle is turning sharply or braking urgently. The control algorithm uses sliding mode control technology to ensure that the yaw control can still maintain high robustness when the vehicle operating 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 is used to adjust the braking force distribution of each wheel; 5) Coordinated distribution of braking force. Coordinate yaw rate control and wheel slip suppression control, recalculate the expected braking force of each wheel required to simultaneously meet yaw stability and prevent wheel slip, and calculate the expected brake chamber pressure to achieve reasonable distribution of braking force between each wheel; 6) Braking force delay compensation control: Since the pneumatic brake system of heavy commercial vehicles has a response lag problem, a prediction model is used to compensate for the braking delay. Before the braking operation, the delay behavior of the braking system is predicted according to the dynamic state of the vehicle, and the braking force output is adjusted in advance, thereby improving the vehicle's response speed and control accuracy.

4. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 1, characterized in that: The system model established in step 1) includes: 11) Nonlinear lateral, longitudinal and vertical vehicle model: Where M represents the total mass of the vehicle, I x and I z are the moments of inertia around the vehicle's center of gravity, X-axis and Z-axis, respectively, and I xz / I zx is the inertia product of the X-axis and the Z-axis; v x and v y They represent the longitudinal speed and lateral speed of the vehicle respectively; the cornering stiffness of the front and rear wheels are C αf and C αr , δ f Indicates the front wheel steering angle, F b is the braking force, fl, fr, rl, rr represent the left front, right front, left rear and right rear wheels respectively; ∈ f and ∈ r is the yaw angle error of the front and rear axles, C ∈f and C ∈r M is the proportional constant of the front and rear axles related to the vehicle roll angle; s represents the mass of the vehicle suspension, g is the acceleration due to gravity, L f and L r are the distances from the front and rear wheels to the vehicle's center of gravity, h s is the vertical distance from the center of mass of the suspension to the yaw axis; K φ is the suspension roll stiffness coefficient, C φ is the suspension roll damping coefficient. represents the vehicle yaw rate, β is the vehicle sideslip angle, φ is the vehicle roll angle, and F y is the lateral ground force; 12) Wheel slip dynamics model: R represents the effective radius of the wheel, V x is the wheel center speed, ω w is the wheel angular velocity, I w is the moment of inertia of the wheel, and α w represents the angular acceleration of the wheel; the bearing force on the wheel is F c , the force perpendicular to the ground is F z , braking torque is τ b Indicates; α is the tire side slip angle, μ x is an estimate of the longitudinal friction coefficient in the tire model; the normal force It represents the force between the tire and the ground, calculated by considering the independent masses of the front and rear axles of the vehicle; 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 1, characterized in that: In order to efficiently calculate the vehicle state parameters, the step 2) assumes that the spring mass rolls around the longitudinal axis of the vehicle, while the rolling of the unsprung mass is negligible, and that the sprung and unsprung masses yaw around a vertical axis passing through a point on the roll axis, and that 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; and 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 according to claim 1, characterized in that: The specific steps of yaw rate control in step 3) include: 31) By using the linear three-degree-of-freedom reference dynamic model of step 22), the time derivative of the state vector is set to zero, and the steady-state value χ as a function of speed and front wheel steering angle is obtained. ss (t) = -A(v x ) -1 bδ f (t), and calculate the expected yaw rate 32) Through the dynamic model equation in step 21), the yaw angular acceleration is obtained as follows: 33) Establish the sliding membrane surface by using the actual yaw rate collected in step 1), the expected yaw rate obtained in step 31) and the yaw acceleration obtained in step 32). and its derivative 34) By applying the power rate exponential reaching law, the yaw rate control input can be obtained as follows: The power-speed exponential reaching law is a reaching strategy for sliding mode control. By properly selecting the control gain K0, the power parameter β0, and other control parameters δ0, γ0, and φ0, rapid convergence, effective suppression of chattering, and improved system robustness can be achieved. Among them, K0 determines the arrival speed of the system. A larger K0 can speed up the arrival of the sliding surface, but may increase chattering. The value of β0 is in the range of 0<β0<0.5, which affects the convergence speed and chattering suppression effect. A larger β0 can reduce chattering, but reduce the convergence speed, while a smaller β0 has the opposite effect. By properly configuring these parameters, the power-speed exponential reaching law can effectively cope with external disturbances and system uncertainties, and achieve fast and stable control effects. The specific mathematical expression of the power-speed exponential reaching law is as follows:

7. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 1, 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) calculates the slip rate of each wheel using the rotation speed of each wheel and the longitudinal speed of the vehicle collected in step 1) 42) Given the expected slip ratio of each wheel, a sliding film surface corresponding to the slip suppression control of each wheel is established according to the slip ratio calculated in step 41). s 2，ij (t) = λ ij (t)-λ ij，ref , and its derivative 43) By applying the power-speed exponential approach law, the wheel slip suppression control input, i.e., the desired braking torque of each wheel, can be obtained as follows: The power-rate exponential reaching law is a reaching strategy for sliding mode control. By properly selecting the control gain K0, the power parameter β0 and other control parameters δ0, γ0 and φ0, fast convergence, effective chattering suppression and improved system robustness can be achieved. Among them, K0 determines the arrival speed of the system. A larger K0 can speed up the arrival of the sliding surface, but may increase chattering. The value of β0 is in the range of 0<β0<0.5, which affects the convergence speed and chattering suppression effect. A larger β0 can reduce chattering but reduce the convergence speed, while a smaller β0 has the opposite effect. By properly configuring these parameters, the power-rate exponential reaching law can effectively cope with external disturbances and system uncertainties, and achieve fast and stable control effects. The specific mathematical expression of the power-rate exponential reaching law is as follows:

8. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 1, characterized in that: The specific steps of the coordinated distribution of braking force in step 5) include: 51) According to the desired braking torque of each wheel obtained in step 43), the braking force required by each wheel is calculated: 52) Recalculate the braking force required by the front outer wheel according to whether the vehicle turns left or right; 53) Calculate the braking torque required for the front outer wheel: τ bij (t)=F b，ij (t)R ij -α w，ij (t)I w，ij ; 54) Calculate the expected brake chamber pressure required for each wheel:

9. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 1, characterized in that: The specific steps of the braking force delay compensation control in step 6) include: 61) The state prediction model is established as follows: 62) The predicted brake chamber pressure is calculated by the prediction model 63) The predicted brake chamber pressure and the desired brake chamber pressure calculated in step 53) are input into the PID controller to obtain the brake chamber control input.

10. The heavy commercial vehicle yaw control method with delay compensation and slip suppression according to claim 1, characterized in that: The step 52) calculates the braking force required by the front outer wheel and makes a judgment including: 511) When the vehicle turns left, the braking force of the front outer wheel, i.e., the right front wheel, is reduced to generate a counterclockwise external yaw moment, and the braking force is calculated by the following formula: 512) When the vehicle turns right, 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:

Images