CN-116353576-B - Active steering and differential braking integrated rollover prevention control method

CN116353576BCN 116353576 BCN116353576 BCN 116353576BCN-116353576-B

Abstract

The invention belongs to the technical field of vehicle engineering, and relates to an active steering and differential braking integrated rollover prevention control method, which comprises the steps of constructing a tractor steering and differential braking integrated dynamics model; setting the rotation angle and braking moment constraint based on the road adhesion coefficient, and solving the constraint optimization problem by using the quadratic programming to obtain the optimal control quantity output. The dynamic estimation of the road surface adhesion coefficient is introduced into the constraint of the front wheel rotation angle and the yaw moment of the trailer, the tire slip phenomenon of the vehicle under the low adhesion road surface caused by insufficient adhesion can be effectively reduced, the problem that the static value cannot be adapted to any working condition in real time is solved, meanwhile, the controller is arranged by adopting a model prediction method, the future state of the vehicle is predicted in advance, the driving safety is improved, the adaptability of the rollover prevention control of the articulated vehicle under the low adhesion coefficient road surface can be effectively improved, and the rollover prevention control effect is practically enhanced by adopting an integrated method.

Inventors

LI HONGXUE
LIU LIANGSHENG

Assignees

燕山大学

Dates

Publication Date: 20260512
Application Date: 20230330

Claims (4)

1. The active steering and differential braking integrated rollover prevention control method is characterized by comprising the following steps of: S1, constructing a tractor trailer steering and braking rollover prevention model, which comprises a tractor and a trailer dynamics model; S2, establishing an anti-rollover controller by adopting a model prediction method, and predicting the future state of the semi-trailer in a prediction stage; S3, based on real-time estimated road surface adhesion coefficients, dynamically setting constraint conditions of front wheel turning angles, yaw moments of a tractor and yaw moments of a trailer in a cooperative mode, solving constraint optimization problems by using a quadratic programming algorithm, and obtaining optimal control quantity output; based on the road surface adhesion coefficient estimated in real time, constraint conditions of front wheel rotation angle, yaw moment of the tractor and yaw moment of the trailer are set in a collaborative dynamic mode, and the constraint conditions are specifically as follows: adding the tire adhesion limit to the constraint: (20), In the formula, For the maximum longitudinal force of the tire, For the vertical load of the tyre, Is the tire lateral force; Maximum yaw moment of tractor: (21), Maximum yaw moment of trailer: (22), In the middle of , The maximum yaw moment of the tractor and the trailer is divided, , , For the maximum longitudinal force of the tractor tire, , , For the maximum longitudinal force of the trailer tires, , The wheelbases of the tractor and the trailer are respectively; solving a constraint optimization problem by using a quadratic programming algorithm to obtain an optimal control quantity, wherein the optimal control quantity comprises the following specific steps: the optimal objective function is converted into the following by matrix series deduction: (23) Wherein, the , , ; To sum up, solving an objective function by using a quadratic programming method: (24), Adding a constraint based on road adhesion coefficient to the front wheel rotation angle and the tractor and trailer yaw moment: (25) Wherein the method comprises the steps of Is that The matrix is formed by a matrix of, , 、 Are all Is a matrix of the (c) in the matrix, , , , Constraint on control increment: (26), Adding constraints to the vehicle state: (27), Solving the objective function with constraint through a quadratic programming algorithm to obtain a series of control increments: (28), the last entered control amount is added to the first element of the control sequence to obtain the control amount at that moment: (29)。
2. The method for integrated anti-rollover control of active steering and differential braking according to claim 1, wherein the method comprises the following steps: In the step S1, a tractor steering and differential braking dynamics model is established: Tractor steering and differential braking integrated dynamics equation: (1) (2) (3) wherein: in order for the mass of the tractor to be of the same type, For the instantaneous speed of the center of mass of the tractor, For the center of mass slip angle of the tractor, For the yaw angle of the tractor, In order for the truck-mounted sprung mass to be of a type, For the distance of the tractor centroid to the roll axis, In order for the roll angle of the tractor, For the purpose of pulling the front axle side force, For the front wheel corner of the tractor, For the rear axle side force of the tractor, For the force of the hinge point, Is a tractor winding The moment of inertia of the shaft, For the sprung mass yaw roll inertia product of the tractor, For the distance of the tractor centroid to the front axle, For the distance of the rear axle of the tractor centroid tract, For the distance of the tractor centroid to the hinge point, Is a tractor winding The moment of inertia of the shaft, The acceleration of the gravity is that, For the cornering stiffness of the tractor, For the purpose of tractor roll damping, For the cornering stiffness of the hinge point, Is the side dip angle of the trailer, Distance from the articulated point to the roll axis of the tractor; trailer steering and differential braking integrated dynamics model: (4) (5) (6) wherein: For the mass of the trailer, the weight of the trailer, Is the slip angle of the mass center of the trailer, Is the yaw angle of the trailer and, Is the instantaneous speed of the center of mass of the trailer, Is the sprung mass of the trailer, and the spring is arranged on the mass, Is the distance between the center of mass of the trailer and the trailer axle, Is the side force of the rear axle of the trailer, In order to provide a hinge angle, the hinge angle, For trailer winding The moment of inertia of the shaft, For the yaw roll inertia product of the sprung mass of the trailer, Is the distance between the center of mass of the trailer and the trailer axle, Is the distance between the center of mass of the trailer and the hinge point, For trailer winding The moment of inertia of the shaft, For the roll stiffness of the trailer, For the purpose of trailer roll damping, Distance from the articulation point to the trailer roll axis; tractor and trailer kinematic constraints: (7), adopting a linear tire model, wherein the tire slip angle is not more than The lateral force of each axle of the trailer is therefore equal to the product of the cornering stiffness and the cornering angle: (8)。
3. the method for integrated anti-rollover control of active steering and differential braking according to claim 2, wherein the method comprises the steps of: The step S2 adopts a model prediction method to design a controller, and specifically comprises the steps of selecting a control quantity ; The state space equation of the tractor and trailer steering and differential braking dynamics model and kinematic constraint are combined to obtain: (9) In the middle of , (10) (11) (12) (13), Discretizing the continuous state space model by adopting forward Euler method, wherein the sampling time is The discrete state space equation is: (14) Wherein: , ; setting: , ; combining equation (9) and the set state quantity Control increment , (15) Wherein, the , 。
4. The integrated active steering and differential braking rollover prevention control method of claim 3, wherein: step S2, predicting the future state of the semitrailer; Setting the prediction time domain as The control time domain is The future state of the semitrailer is predicted by combining equation (15), and the following can be obtained: (16), by combining equations (15) and (16), the relation between the output quantity and the state quantity in the prediction time domain and the control increment can be obtained: (17) (18) Wherein: , , , , In order to keep the vehicle state of the semitrailer up with the expected value in the prediction horizon, an objective function is set In order to ensure that the vehicle is stable and the control input is small, an objective function is set To ensure that the equation is solved and is convenient for compact calculation, a relaxation factor is set as The weight coefficient is Obtaining a final optimized objective function: (19), In the formula, The output in the time domain of the prediction, In order to predict the desired value of the output in the time domain, To control the vehicle angle in the time domain and the yaw moment control increment of the tractor and the semitrailer, A state weighting matrix that is semi-positive, The weighting matrix is controlled for positive determination.

Description

Active steering and differential braking integrated rollover prevention control method Technical Field The invention belongs to the technical field of vehicle engineering, and relates to an active steering and differential braking integrated rollover prevention control method. Background The high-speed development and logistics of electronic commerce just need, the market demand of heavy tractor safety is strengthened, and heavy semitrailer plays an important role in improving logistics efficiency and comprehensive economic benefit. However, due to the large tonnage of the semitrailer, high gravity center and other factors, the road surface working condition is changed under the influence of weather, and the accidents such as rollover and folding are very easy to occur. The existing research on rollover prevention control of the hinged automobile trains is mostly focused on independent steering or differential braking control, and the adaptability and the effectiveness of the rollover prevention control method under the condition of low adhesion road surfaces are lacking. Therefore, active steering and differential braking integrated control is adopted, a predictive control method of a predictive stage model is adopted, and meanwhile yaw moment constraint based on road adhesion coefficient is added into the predictive model, so that braking slip is prevented, and the method becomes a key for improving the active safety of the semi-trailer. Disclosure of Invention In order to overcome the problems in the prior art, the invention provides an active steering and differential braking integrated rollover prevention control method which adopts active steering and differential braking integrated control, adopts a model prediction control method with a prediction stage, improves the rollover prevention control effect, prevents a vehicle from slipping through the constraint of setting a corner and braking moment by a road adhesion coefficient, and improves the active safety of a semitrailer on a low adhesion road surface. The technical scheme for solving the problems is that the active steering and differential braking integrated rollover prevention control method is characterized by comprising the following steps of: S1, constructing a tractor trailer steering and braking rollover prevention model, which comprises a tractor and a trailer dynamics model; S2, establishing an anti-rollover controller by adopting a model prediction method, and predicting the future state of the semi-trailer in a prediction stage; And S3, setting corner and yaw moment constraints based on road adhesion coefficients, and solving constraint optimization problems by using a quadratic programming algorithm to obtain optimal control quantity output. Further, in the step S1, a tractor steering and differential braking dynamics model is established: Tractor steering and differential braking integrated dynamics equation: Wherein m 1 is the tractor mass, u 1 is the instantaneous speed of the tractor centroid, beta 1 is the tractor centroid side deflection angle, ψ 1 is the tractor yaw angle, m 1s is the tractor sprung mass, h 1 is the distance of the tractor centroid to the roll axis, phi 1 is the tractor roll angle, F 1 is the front axle side force, delta is the tractor front wheel angle, F 2 is the tractor rear axle side force, F 4 is the hinge point acting force, I 1zz is the rotational inertia of the tractor about the Z axis, I 1xz is the yaw inertia product of the tractor sprung mass, a is the distance of the tractor centroid to the front axis, b is the distance of the tractor centroid channel back axis, c is the distance of the tractor centroid to the hinge point, I xx is the rotational inertia of the tractor about the X axis, g is the gravity acceleration, k r1 is the tractor side deflection stiffness, c 1 is the tractor roll damping, k 12 is the hinge point side deflection stiffness, phi 2 is the trailer side deflection angle, h 1c is the distance of the tractor roll axis to the hinge point; trailer steering and differential braking integrated dynamics model: Wherein m 2 is the mass of the trailer, beta 2 is the side deflection angle of the mass center of the trailer, psi 2 is the yaw angle of the trailer, u 2 is the instantaneous speed of the mass center of the trailer, m 2x is the sprung mass of the trailer, h 2 is the distance from the mass center of the trailer to the trailer axle, F 3 is the lateral force of the rear axle of the trailer, Γ is the hinging angle, I 2zz is the moment of inertia of the trailer about the Z axis, I 2xz is the yaw inertia product of the sprung mass of the trailer, d is the distance from the mass center of the trailer to the trailer axle, e is the distance from the hinging point of the mass center of the trailer, I 2xx is the moment of inertia of the trailer about the X axis, k r2 is the roll stiffness of the trailer, c 2 is the roll damping of the trailer, h 2c is the distance from the hinging point to the