Vehicle queue transverse and longitudinal cooperative control method with external disturbance, input time delay and communication time delay

Abstract

The invention belongs to the technical field of automobile control, and discloses a vehicle queue transverse and longitudinal cooperative control method with external disturbance, input time delay and communication time delay. Comprising the steps that S1, a vehicle queue model is established, wherein the vehicle queue model comprises a vehicle longitudinal model considering longitudinal input time lag and communication time lag and a vehicle transverse model considering transverse input time lag; s2, designing a queue transverse and longitudinal cooperative controller, wherein the transverse and longitudinal cooperative controller comprises a longitudinal controller designed based on the vehicle longitudinal model and a transverse controller designed based on the vehicle transverse model; s3, controlling the vehicle to run transversely and longitudinally through the transverse and longitudinal cooperative controller: ensuring that the expected distance between the target following vehicle and the pilot vehicle is kept and the speed of the pilot vehicle is tracked through the longitudinal controller; and controlling the target following vehicle to move along the central line of the road through the transverse controller.

Description

Technical Field

[0001] The present invention belongs to the technical field of automobile control, and in particular relates to a method for horizontal and vertical coordinated control of a vehicle queue with external disturbance, input lag and communication delay. Background Art

[0002] In the past few decades, the rapid increase in the number of cars has brought great challenges to energy security and traffic safety. According to the National Highway Traffic Safety Administration, about 84% of traffic accidents are caused by human factors. Vehicle platooning can significantly reduce traffic accidents caused by driver fatigue and misoperation, thereby improving road traffic safety. In addition, vehicle platooning (especially heavy truck platooning) can reduce air resistance between vehicles, thereby reducing emissions and fuel consumption, and improving road capacity. It is precisely because of these potential benefits that vehicle platoon control has attracted more and more scholars.

[0003] Vehicle platoon control technology mainly includes longitudinal control and lateral control. The goal of longitudinal control is to ensure that vehicles in the platoon travel at the same speed and maintain the desired distance between adjacent vehicles; lateral control requires vehicles in the platoon to travel along the center line of the lane and avoid exceeding the road boundary. However, in actual vehicle platoon control, vehicles are often affected by communication delays when obtaining information from communicating vehicles, and delays often show random distribution characteristics. In addition, actuators may also be affected by delays when receiving control instructions, resulting in deviations between execution actions and expected moments. The existence of delays makes it difficult for vehicles to respond quickly according to real-time traffic conditions, which in turn leads to increased queue length, longer queue time, and even traffic congestion. More importantly, the response lag caused by delays will affect the execution speed of vehicles when they need to quickly adjust their driving strategies, thereby exacerbating the instability of the platoon. Delays will also reduce control accuracy, causing vehicles to make decisions based on outdated or incomplete information, thereby weakening the control performance of the entire platoon. Summary of the invention

[0004] In view of this, in order to solve the problems raised in the above background technology, an object of the present invention is to provide a vehicle queue horizontal and vertical cooperative control method with external disturbance, input lag and communication delay.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay comprises the following steps:

[0007] S1. Establishing a vehicle platoon model

[0008] The vehicle platoon model includes a vehicle longitudinal model taking into account longitudinal input time lag and communication time lag, and a vehicle lateral model taking into account lateral input time lag;

[0009] S2. Design of horizontal and vertical collaborative controller

[0010] The longitudinal and transverse coordinated controller includes a longitudinal controller designed based on the longitudinal model of the vehicle and a transverse controller designed based on the transverse model of the vehicle;

[0011] S3. Control the vehicle's horizontal and vertical travel through the horizontal and vertical coordinated controller

[0012] The longitudinal controller ensures that the target following vehicle maintains a desired vehicle spacing with the pilot vehicle and tracks the speed of the pilot vehicle;

[0013] The target following vehicle is controlled to move along the center line of the road by the lateral controller.

[0014] Preferably, the expression of the vehicle longitudinal model is:

[0015]

[0016] Among them, s i , a i are the longitudinal position, velocity and acceleration of the i-th vehicle, κ i represents the longitudinal dynamics time constant, represents the longitudinal control input, t x,i (t) is the unknown bounded longitudinal input lag of the accelerator and brake pedals, And the longitudinal input lag t x,i The derivative of (t) has an upper bound, namely

[0017] Preferably, the communication time delay from vehicle j to vehicle i is expressed as t ci,j ,and

[0018] Preferably, select x i =[s i ,v i ,a i ] T As the longitudinal system state of the i-th vehicle, the following error expression when the target following vehicle follows the speed of the pilot vehicle is: Among them, d i,j =[(ij)d des 00] T , d des Indicates the expected spacing error.

[0019] Preferably, the expression of the longitudinal controller is:

[0020]

[0021] Among them, K x,i represents the longitudinal control gain, η i-1 (tt ci ) indicates that vehicle i-1 sends observation information with communication delay to vehicle i, x0(tt ci,0 ) indicates that the pilot vehicle sends observation information with communication delay to vehicle i. The communication delay state includes the communication delay t ci , ε is a constant greater than zero and η i (t)=0,t<0.

[0022] Preferably, the longitudinal control gain K x,i The expression is:

[0023] K x,i =YM -1 ;

[0024]

[0025] Ψ1(1,2)=PM-αM T A T ;

[0026]

[0027]

[0028] Among them, the positive symmetric matrices P, Q, R, S and matrices S, M, Y can be solved by the Yalmip toolbox in Matlab

[0029] Preferably, the vehicle lateral model is constructed based on a two-degree-of-freedom bicycle model, and the expression of the two-degree-of-freedom bicycle model is:

[0030]

[0031] in, represents the lateral velocity of the i-th vehicle, represents the yaw rate of the i-th vehicle, represents the moment of inertia about the z-axis, l f,i and l r,i Respectively represent the distance from the front and rear axles to the center of mass, F i f and F i r Represent the lateral forces of the front and rear tires respectively.

[0032] Preferably, the state space equation of the lateral error model is:

[0033]

[0034] in, represents the lateral position error between the center of mass of the i-th vehicle and the center line of the lane, represents the heading error of the i-th vehicle relative to the center line of the lane, represents the lateral control input, and Denote the cornering stiffness of the front and rear tires, t y,i (t) represents the unknown lateral input delay of the actuator, and

[0035] Preferably, the expression of the lateral controller is:

[0036]

[0037] in, K y,i represents the lateral control gain.

[0038] Preferably, the lateral control gain K y,i The expression is:

[0039] K y,i =VL -1 ;

[0040]

[0041] Among them, the matrix L>0, R>0, W>0 is solved by the Yalmip toolbox in Matlab.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention constructs a lateral and longitudinal decoupling control framework including a lateral controller and a longitudinal controller. The lateral controller ensures that the vehicle can follow the center line of the road under the premise of considering the execution delay, and the longitudinal controller ensures that each following vehicle can follow the state of the lead vehicle and maintain a safe vehicle distance with the adjacent vehicles under the premise of considering the execution delay and communication delay, thereby effectively realizing the stable formation and form of the fleet, and allowing arbitrarily large input and communication delays during the formation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A block diagram of the horizontal and vertical coordinated control of a commercial vehicle fleet based on the present invention;

[0045] Figure 2is a block diagram of the horizontal and vertical coordinated control of the i-th vehicle in a commercial vehicle fleet based on the present invention;

[0046] Figure 3 Schematic diagram of the two-degree-of-freedom bicycle model. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] A method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay comprises the following steps:

[0049] S1. Establishing a vehicle platoon model

[0050] The vehicle platoon model includes a vehicle longitudinal model taking into account longitudinal input time lag and communication time lag, and a vehicle lateral model taking into account lateral input time lag;

[0051] (11) About the vehicle longitudinal model

[0052] The longitudinal dynamics model of the i-th vehicle in the platoon is described as the following third-order linear model:

[0053]

[0054] Among them, s i , a i are the longitudinal position, velocity and acceleration of the i-th vehicle, κ i represents the longitudinal dynamics time constant, represents the longitudinal control input, t x,i (t) is the unknown bounded longitudinal input lag of the accelerator and brake pedals, And the longitudinal input lag t x,i The derivative of (t) has an upper bound, namely

[0055] use represents the longitudinal system state of the i-th vehicle, and the above results show that:

[0056]

[0057] in,

[0058] (12) About the vehicle lateral model

[0059] The vehicle lateral model is based on Figure 3 The two-degree-of-freedom bicycle model shown is constructed, and the expression of the two-degree-of-freedom bicycle model is:

[0060]

[0061] in, represents the lateral velocity of the i-th vehicle, represents the yaw rate of the i-th vehicle, represents the moment of inertia about the z-axis, l f,i and l r,i Respectively represent the distance from the front and rear axles to the center of mass, F i f and F i r Represent the lateral forces of the front and rear tires respectively.

[0062] Assume that the tire operates in the linear region, that is, the tire lateral force can be calculated using the small angle approximation method:

[0063]

[0064] in, and Denote the cornering stiffness of the front and rear tires, δ i Indicates the front wheel turning angle.

[0065] From the above, the lateral dynamics model of vehicle i can be comprehensively expressed as:

[0066]

[0067] Generally speaking, lateral control hopes that the vehicles in the queue move along the center line of the road, that is, the actual driving path is consistent with the reference path, and the error between the two should be close to zero. Therefore, the lateral error model is introduced.

[0068] The lateral position error between the center of mass of the i-th vehicle and the lane centerline is expressed as The heading error of the i-th vehicle relative to the lane centerline is expressed as The lateral error model is expressed as:

[0069]

[0070] in, is the heading angle of vehicle i, represents the direction angle of the lane centerline, represents the desired yaw rate, c i is the road curvature.

[0071] use represents the lateral state of the i-th vehicle, represents the lateral control input, t y,i (t) represents the unknown lateral input delay of the actuator. And the lateral input delay has an upper bound The derivative of the lateral input lag also has an upper bound

[0072] In summary, the vehicle lateral model can be expressed as:

[0073] in:

[0074]

[0075] S2. Design of a Horizontal and Vertical Cooperative Controller for Vehicle Platoons

[0076] The longitudinal and transverse coordinated controller includes a longitudinal controller designed based on the longitudinal model of the vehicle and a transverse controller designed based on the transverse model of the vehicle;

[0077] (21) About the longitudinal controller

[0078] Vertical controller

[0079] Considering the communication delay t ci,i-1 The communication topology between the leading vehicle and the pilot vehicle. ci,j represents the communication delay from vehicle j to vehicle i, and the communication delay has an upper bound The derivative of the communication delay also has an upper bound Design the following control law:

[0080] However, due to data delay or loss (equivalent to delay) in vehicle-to-vehicle communication, the vehicle platoon may be unstable. In order to ensure the consistency of tracking error, each following vehicle in the platoon should know the state information of the leading vehicle. Therefore, the following distributed observer is designed to estimate the state of the leading vehicle:

[0081]

[0082] where ε is a constant greater than zero and η i (t)=0,t≤0. η i-1 (tt ci ) indicates that vehicle i-1 sends observation information η to vehicle i i The communication delay of (t) is t ci (i.e. η i-1 (tt ci ) indicates that vehicle i-1 passes through the communication delay t ci,i-1 The channel sends observation information η to vehicle i i (t)), similarly, x0(ttci,0 ) indicates that the pilot vehicle sends observation information η to vehicle i i The communication delay of (t) is t ci,0 .

[0083] In summary, the longitudinal controller is expressed as: Among them, K x,i represents the longitudinal control gain.

[0084] The longitudinal control gain K x,i It can be obtained by solving the linear matrix inequality:

[0085]

[0086] Ψ1(1,2)=PM-αM T A T ;

[0087]

[0088] Among them, P, Q, R, S are the positive definite matrices to be solved and S, M, Y are the matrices to be solved. If the linear inequality has a feasible solution, then K x,i =YM -1 .

[0089] (22) About lateral controller

[0090] The control goal of the lateral performance of the fleet is to follow the center line of the road. The output of the lateral controller is designed to be And design the lateral tracker:

[0091]

[0092] in,

[0093] Further design a memoryless H ∞ The state feedback controller makes the closed-loop system of the lateral tracker asymptotically stable and has the following performance indicators:

[0094]

[0095] In summary, the feedback lateral controller is obtained as: Among them, K y,i represents the lateral control gain.

[0096] The lateral control gain K y,i It can be obtained by solving the following matrix inequality:

[0097]

[0098] Among them, L>0, R>0, W>0, M and N are variables to be solved. If the linear matrix inequality has a feasible solution, then K y,i =VL -1 .

[0099] S3. Control the vehicle's horizontal and vertical travel through the horizontal and vertical coordinated controller

[0100] (31) ensuring that the target following vehicle maintains a desired vehicle spacing with the lead vehicle and tracks the speed of the lead vehicle through the longitudinal controller;

[0101] The following error when the target following vehicle follows the speed of the pilot vehicle is expressed as: Among them, d i,j =[(ij)d des 00] T , d des represents the expected distance error. Based on this, the specific control of this step can be regarded as controlling the following error between the target following vehicle and the leading vehicle to be infinitely close to 0, and the target following vehicle and the leading vehicle maintain the expected vehicle distance d des .

[0102] (32) controlling the target following vehicle to move along the center line of the road by the lateral controller;

[0103] The specific control means that the lateral position error and heading error of each vehicle are as close to zero as possible, that is, the lateral position error between the center of mass of vehicle i and the center line of the lane is Approaching 0, the heading error of vehicle i relative to the center line of the lane Approaching 0.

[0104] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbances, input lags and communication delays, characterized in that: The steps include: S1. Establishing a vehicle platoon model The vehicle platoon model includes a vehicle longitudinal model taking into account longitudinal input time lag and communication time lag, and a vehicle lateral model taking into account lateral input time lag; S2. Design of horizontal and vertical collaborative controller The longitudinal and transverse coordinated controller includes a longitudinal controller designed based on the longitudinal model of the vehicle and a transverse controller designed based on the transverse model of the vehicle; S3. Control the vehicle's horizontal and vertical travel through the horizontal and vertical coordinated controller The longitudinal controller ensures that the target following vehicle maintains a desired vehicle spacing with the pilot vehicle and tracks the speed of the pilot vehicle; The target following vehicle is controlled to move along the center line of the road by the lateral controller.

2. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input delay and communication delay according to claim 1, characterized in that: The expression of the vehicle longitudinal model is: Among them, s i , a i are the longitudinal position, velocity and acceleration of the i-th vehicle, κ i represents the longitudinal dynamics time constant, represents the longitudinal control input, t x,i (t) is the unknown bounded longitudinal input lag of the accelerator and brake pedals, And the longitudinal input lag t x,i The derivative of (t) has an upper bound, namely 3. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay according to claim 2, characterized in that: The communication delay from vehicle j to vehicle i is expressed as t ci,j ,and 4. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay according to claim 3, characterized in that: Select x i =[s i ,v i ,a i ] T As the longitudinal system state of the i-th vehicle, the following error expression when the target following vehicle follows the speed of the pilot vehicle is: Among them, d i,j =[(ij)d des 00] T , d des Indicates the expected spacing error.

5. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay according to claim 4, characterized in that: The expression of the longitudinal controller is: Among them, K x,i represents the longitudinal control gain, η i-1 (tt ci ) indicates that vehicle i-1 sends observation information with communication delay to vehicle i, x0(tt ci,0 ) indicates that the pilot vehicle sends observation information with communication delay to vehicle i. The communication delay state includes the communication delay t ci , ε is a constant greater than zero and η i (t)=0,t<0.

6. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay according to claim 5, characterized in that: The longitudinal control gain K x,i The expression is: K x,i =YM -1 ; Ψ1(1,2)=PM-αM T A T ; Among them, the positive definite symmetric matrices P, Q, R, S and matrices S, M, Y can be solved using the Yalmip toolbox in Matlab.

7. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input delay and communication delay according to claim 1, characterized in that: The vehicle lateral model is constructed based on a two-degree-of-freedom bicycle model, and the expression of the two-degree-of-freedom bicycle model is: in, represents the lateral velocity of the i-th vehicle, represents the yaw rate of the i-th vehicle, represents the moment of inertia about the z-axis, l f,i and l r,i Respectively represent the distance from the front and rear axles to the center of mass, F i f and F i r Represent the lateral forces of the front and rear tires respectively.

8. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input lag and communication delay according to claim 7, characterized in that: The state space equation of the lateral error model is: in, represents the lateral position error between the center of mass of the i-th vehicle and the center line of the lane, represents the heading error of the i-th vehicle relative to the center line of the lane, represents the lateral control input, and Denote the cornering stiffness of the front and rear tires, t y,i (t) represents the unknown lateral input delay of the actuator, and 9. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input delay and communication delay according to claim 8, characterized in that: The expression of the lateral controller is: in, K y,i represents the lateral control gain.

10. The method for lateral and longitudinal coordinated control of a vehicle platoon with external disturbance, input delay and communication delay according to claim 9, characterized in that: The lateral control gain K y,i The expression is: K y,i =VL -1 ; Among them, the matrix L>0, R>0, W>0 can be solved by the Yalmip toolbox in Matlab.

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