Control method for enhancing CAV platoon strength in mixed traffic flow under vehicle-road cooperation

Abstract

The application discloses a control method for enhancing the formation strength of a CAV vehicle team in a mixed traffic flow under vehicle-road cooperation, and the method comprises the following steps: determining a vehicle to be formed and a target team according to the method; obtaining driving information and road environment information of all vehicles within the communication radius range of the target team and the vehicle to be formed through the interaction between a roadside unit and a vehicle communication unit, and exchanging the obtained information through inter-vehicle communication; controlling the vehicle to be formed or the team to drive to a formation area according to the obtained information, and realizing speed cooperation through a speed management module, so that the rear vehicle of the target team slows down to expand a gap, and the vehicle to be formed or the team is sequentially controlled to be formed into the target team from the rear when the widened gap is sufficient to meet the time and space conditions for the safe formation of the vehicle to be formed. The control method can reduce the interference of surrounding other vehicles on the CAV vehicle or small CAV team in the mixed traffic flow, safely and efficiently form the CAV team, enhance the formation strength of the CAV team, and improve the road traffic capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of traffic control systems of road vehicles, in particular to a control method for enhancing the formation strength of a CAV vehicle fleet in a mixed traffic flow under vehicle-road cooperation. BACKGROUND

[0002] Intelligent networked and automated driving cars (CAV) are equipped with advanced on-board sensors, controllers, actuators and other devices, and integrate modern communication and network technologies to achieve V2X intelligent information exchange and sharing, with complex environmental perception, intelligent decision-making, cooperative control and execution functions, and can achieve safe, comfortable, energy-saving and efficient driving, and ultimately replace human operation as a new generation of cars. In recent years, the platooning of intelligent networked and automated driving cars has attracted great attention. In the platoon of intelligent networked and automated driving cars, the vehicles in the platoon can be adjusted to maintain the same required speed and travel at a pre-set distance between vehicles. Both theoretical analysis and practice have confirmed that platooning can achieve higher traffic efficiency, better safety and lower energy consumption.

[0003] However, it is still difficult for intelligent networked and automated driving cars to achieve 100% penetration. As automated driving cars are gradually deployed, it is inevitable that there will be a long period of time in the future when road traffic flow is in a mixed traffic flow state, i.e. automated driving cars and human-driven cars coexist. The uncertainty of human driving behavior is difficult to quantify, which will also bring certain challenges to the platooning of intelligent networked and automated driving cars. In the face of the mixed traffic flow situation that will exist for a long time in the future, it is inevitable that there will be interference from surrounding human-driven vehicles during the process of enhancing the formation strength of intelligent networked and automated driving cars, which will affect the efficiency and safety of the platoon. Therefore, it is urgent to explore a control method for enhancing the safe and efficient platooning of intelligent networked and automated driving cars in a mixed traffic flow. SUMMARY

[0004] The purpose of the present application is to provide a control method for enhancing the formation strength of a CAV vehicle fleet in a mixed traffic flow under vehicle-road cooperation, which expands the space of the target fleet, enabling the vehicle or fleet to be safely and efficiently integrated into the target fleet, thereby achieving the purpose of enhancing the formation strength of the fleet.

[0005] To achieve the above purpose, the technical solutions of the present application are as follows:

[0006] The control method for enhancing the formation strength of a CAV vehicle fleet in a mixed traffic flow under vehicle-road cooperation has the following specific steps:

[0007] S1, the intelligent networked and automated driving fleet publishes the remaining capacity of the fleet to all intelligent networked and automated driving vehicles or small intelligent networked and automated driving fleets within the communication radius of the fleet;

[0008] The intelligent network connection automatic driving car CAV can sense the road environment and share information in real time.

[0009] The remaining capacity of the vehicle platoon is the number of vehicles that can be included in the vehicle platoon, which is equal to the difference between the number of vehicles in the maximum platoon length and the number of vehicles in the current vehicle platoon;

[0010] As the length of the vehicle platoon increases, it negatively contributes to the traffic capacity and traffic flow stability. A longer vehicle platoon length reduces the lateral maneuverability of the vehicle platoon and increases the difficulty of vehicle merging and leaving the platoon, and also poses a great challenge to the control of the vehicle platoon. Therefore, the number of vehicles in the maximum platoon length is 10;

[0011] The communication radius is a circular range of 0-1000 meters;

[0012] S2, the intelligent network connection automatic driving vehicle or small intelligent network connection automatic driving vehicle platoon with platoon demand sends a platoon request to the intelligent network connection automatic driving vehicle platoon and determines the specific conditions of the number of vehicles that can be included, which are divided into the following two cases:

[0013] 1. When the remaining capacity of the vehicle platoon is greater than or equal to the small intelligent network connection automatic driving vehicle platoon, the small intelligent network connection automatic driving vehicle platoon is all as a platoon to be coded;

[0014] 2. When the remaining capacity of the vehicle platoon is less than the small intelligent network connection automatic driving vehicle platoon, the small intelligent network connection automatic driving vehicle platoon is split.

[0015] The small intelligent network connection automatic driving vehicle platoon is half or less than half of the number of vehicles in the maximum platoon length;

[0016] The splitting principle is to split from the front or rear of the small vehicle platoon according to the relative position of the target vehicle platoon and the small intelligent network connection automatic driving vehicle platoon, and the number of split vehicles is the number of remaining capacities of the vehicle platoon, or the target vehicle platoon invites other vehicles or vehicle platoons as included vehicles;

[0017] S3, the intelligent network connection automatic driving vehicle platoon selects and invites the requesting intelligent network connection automatic driving vehicle or small intelligent network connection automatic driving vehicle platoon as a platoon to be coded, and the platoon to be coded determines the intelligent network connection automatic driving vehicle platoon as a target vehicle platoon, the number of vehicles in the target vehicle platoon is greater than or equal to the number of vehicles in the included platoon;

[0018] The specific steps of the screening are as follows:

[0019] S3.1, screen all received requests, first screen the vehicle platoon whose number of included vehicles is equal to the remaining capacity of the target vehicle platoon, if there is, send an invitation to join and confirm that the vehicle platoon is a platoon to be coded, if not, screen the vehicle platoon whose number of included vehicles is greater than the remaining capacity of the target vehicle platoon;

[0020] S3.2, screening the platoon with the number of vehicles greater than the remaining capacity of the target platoon, if any, sending an invitation to the platoon with the least number of vehicles after splitting the platoon, and confirming the new platoon split from the platoon as the to-be-platoon, if not, continue screening the platoon with the number of vehicles less than the remaining capacity of the target platoon;

[0021] S3.3, screening the platoon with the number of vehicles less than the remaining capacity of the target platoon, if any, sending an invitation to the platoon with the most number of vehicles and confirming the platoon as the to-be-platoon, if not, sending an invitation to the single request vehicle and determining it as the to-be-platoon.

[0022] S4, obtaining driving information and road environment information of all vehicles within the communication radius of the target platoon and the platoon vehicle through the road side unit and the vehicle communication unit, and exchanging information through inter-vehicle communication;

[0023] The driving information and road environment information include: the spatial position of the target platoon and the platoon vehicle in the road, the platoon speed, the acceleration and deceleration, the speed and acceleration and deceleration of the front and rear vehicles, and the driving situation and spatial position of the vehicles in the adjacent lane of the target platoon, the number of driving road lanes, the road line type, and the weather condition;

[0024] Wherein, according to the relationship between the obtained spatial position of the target platoon and the to-be-platoon or platoon, the platoon vehicle or platoon can be divided into front or rear of the target platoon, and the division is based on the target gap of the target platoon. The specific position of the platoon vehicle or platoon relative to the target platoon can be divided into six categories, i.e. distributed in the front or rear of the target platoon in the same lane, in the front or rear of the adjacent lane, and in the front or rear of the crossing lane;

[0025] S5, the to-be-platoon drives to the adjacent lane of the target platoon, accelerates or decelerates into the to-be-platoon area according to the driving information and road environment information, and realizes speed coordination through the speed management module;

[0026] The relative position of the target platoon and the to-be-platoon or platoon is different, and the way of entering the to-be-platoon area is different. The platoon vehicle or platoon distributed in the front or rear of the target platoon in the same lane enters the to-be-platoon area by changing lane to the adjacent lane of the target platoon and then accelerating or decelerating; the platoon vehicle or platoon distributed in the front or rear of the adjacent lane of the target platoon enters the to-be-platoon area by accelerating or decelerating; the platoon vehicle or platoon distributed in the front or rear of the crossing lane of the target platoon enters the to-be-platoon area by changing lane to the adjacent lane of the target platoon and then accelerating or decelerating;

[0027] The to-be-compiled area is: taking the road center line as the horizontal axis and being perpendicular to the road center line as the vertical axis, when the horizontal coordinate of the target gap tail vehicle body position of the target vehicle team has the same horizontal coordinate value as the adjacent lane where the compiled vehicle or vehicle team is located, the position is called the to-be-compiled area; if the compilation is a small intelligent networked automatic driving vehicle team, the small intelligent networked automatic driving vehicle team should enter the to-be-compiled area completely;

[0028] The specific steps of realizing speed coordination through the speed management module are as follows:

[0029] S5.1, when there is no obstacle vehicle in front of the compiled vehicle or vehicle team and the target vehicle team, the following expression should be satisfied:

[0030] v in = v p

[0031] In the formula, v in is the required speed of the compiled vehicle or vehicle team, and v p is the speed of the target vehicle team;

[0032] S5.2, when there is an obstacle vehicle in front of the compiled vehicle or vehicle team and no obstacle vehicle in front of the target vehicle team, the following expression should be satisfied:

[0033]

[0034] In the formula, is the speed of the vehicle in front of the compiled vehicle or vehicle team;

[0035] S5.3, when there is no obstacle vehicle in front of the compiled vehicle or vehicle team and there is an obstacle vehicle in front of the target vehicle team, the following expression should be satisfied:

[0036]

[0037] In the formula, is the speed of the vehicle in front of the target vehicle team;

[0038] S5.4, when there are obstacle vehicles in front of the compiled vehicle or vehicle team and the target vehicle team, the following expression should be satisfied:

[0039]

[0040] S6, the target vehicle team tail vehicle expands the gap and compiles the vehicle team when the gap is sufficient to meet the conditions for safe compilation of the to-be-compiled vehicle team, if it is a small vehicle team, the small vehicle team is compiled from the tail of the small vehicle team in turn until the team is completed, and the specific expression is as follows:

[0041] And

[0042] In the formula, Longitudinal distance d between target platoon gap rear vehicle and platoonable vehicle in platoonable area l-g Longitudinal distance d between target platoon gap front vehicle and platoonable vehicle in platoonable area f-g Longitudinal safety distance between target platoon gap rear vehicle and platoonable vehicle in platoonable area Longitudinal safety distance between target platoon gap front vehicle and platoonable vehicle in platoonable area Gap rear vehicle speed v l -g Gap front vehicle speed v f-g Platoonable vehicle or platoon length l, platoonable vehicle or platoon speed v, intelligent connected and automated vehicle (CAV) reaction time Brake delay time t delay Minimum acceleration a min ;

[0043] Further, the target gap is widened and the platoonable vehicle or platoon is controlled to enter the target platoon by using a controller, which is composed of a lateral controller and a longitudinal controller, the lateral controller aims to minimize the lateral position error, and the longitudinal controller aims to minimize the gap error.

[0044] Advantages of the present application

[0045] 1. The control method for enhancing the platoon strength of an intelligent connected and automated vehicle platoon in a mixed traffic flow under the condition of vehicle infrastructure integration reduces the speed of the tail vehicle of the intelligent connected and automated vehicle platoon to expand the target gap, which can ensure that the target gap provides a safe platoon space for the platoonable vehicle or small platoon in the platoonable area, and in the case that the intelligent connected and automated vehicle does not reach a penetration rate of 100%, the interference of non-intelligent connected and automated vehicles around the intelligent connected and automated vehicle platoon is reduced, so that the platoonable vehicle or small platoon can be safely and efficiently platooned to achieve the purpose of platoon driving.

[0046] 2. The present application proposes a speed management module to ensure that the platoonable vehicle or small platoon in the platoonable area is coordinated with the target platoon speed, and the control logic can ensure precise and safe speed coordination of the target platoon and the platoonable vehicle or small platoon when there are no human-driven vehicles in front of the target platoon and the platoonable vehicle or small platoon.

[0047] 3. The present application proposes a screening mechanism for determining the intelligent connected and automated vehicle or small intelligent connected and automated platoon running on the road as a platoonable vehicle, which can determine the platoonable vehicle as the optimal choice under the current environment, improve the efficiency of the target platoon becoming the maximum platoon length, reduce the number of platoon entries to become the maximum platoon length, and to some extent, reduce the impact of the platoon process on traffic flow due to the demand for platooning.

[0048] 4. In a mixed traffic flow environment, the present invention can significantly reduce the headway between vehicles by platooning CAVs, thereby improving driving efficiency and safety, and thus greatly increasing the road's traffic capacity.

[0049] 5. The present invention enhances the formation strength of the CAV fleet, allowing CAVs to gather better, the CAV queue length to reach the maximum and the headroom to be reduced, and the road traffic capacity will be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Flowchart of the control method for enhancing the CAV platooning strength in mixed traffic flow under vehicle-road collaboration;

[0051] Figure 2 Schematic diagram of a control method for enhancing the CAV platooning strength in mixed traffic flow under vehicle-road collaboration;

[0052] Figure 3 It is a rolling horizon control framework;

[0053] Figure 4 Parameter illustration of the control method for enhancing the CAV platooning strength in mixed traffic flow under vehicle-road collaboration. DETAILED DESCRIPTION

[0054] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0055] The present invention provides a control method for enhancing the strength of a platoon of intelligent connected autonomous driving vehicles in a mixed traffic flow under vehicle-road cooperative conditions. The specific steps are as follows:

[0056] like Figure 1 and Figure 2 As shown in Figure 1, the control method for enhancing the CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration is as follows:

[0057] S1. The intelligent connected autonomous driving fleet publishes the remaining capacity of the fleet to all intelligent connected autonomous driving vehicles or small intelligent connected autonomous driving fleets within the fleet communication radius;

[0058] Intelligent connected autonomous vehicles (CAVs) can sense the road environment and share information in real time;

[0059] The remaining capacity of the vehicle fleet is the number of vehicles that can be incorporated into the vehicle fleet, which is equal to the difference between the maximum number of vehicles in the vehicle fleet and the current number of vehicles in the vehicle fleet;

[0060] As the length of the vehicle fleet increases, it negatively contributes to the traffic capacity and traffic flow stability. Longer vehicle fleet length reduces the lateral maneuverability of the vehicle fleet and increases the difficulty of vehicle merging and decoupling, and also poses great challenges to the control of the vehicle fleet. Therefore, the maximum number of vehicles in the vehicle fleet is 10;

[0061] The communication radius is a circular range of 0-1000 meters;

[0062] S2, the intelligent connected automatic driving vehicle or small intelligent connected automatic driving vehicle fleet with platoon demand sends a platoon request to the intelligent connected automatic driving vehicle fleet and determines the specific conditions of the number of vehicles that can be incorporated, which are divided into the following two cases:

[0063] 1. When the remaining capacity of the vehicle fleet is greater than or equal to the small intelligent connected automatic driving vehicle fleet, the small intelligent connected automatic driving vehicle fleet is all as the platoon-to-be;

[0064] 2. When the remaining capacity of the vehicle fleet is less than the small intelligent connected automatic driving vehicle fleet, the small intelligent connected automatic driving vehicle fleet is split.

[0065] The small intelligent connected automatic driving vehicle fleet is half or less than half of the maximum number of vehicles in the platoon;

[0066] The splitting principle is to split from the front or rear of the small vehicle fleet according to the relative position of the target vehicle fleet and the small intelligent connected automatic driving vehicle fleet, and the number of split vehicles is the number of remaining capacity of the vehicle fleet, or the target vehicle fleet invites other vehicles or vehicle fleets as incorporated vehicles;

[0067] S3, the intelligent connected automatic driving vehicle fleet selects and invites the requesting intelligent connected automatic driving vehicle or small intelligent connected automatic driving vehicle fleet as the platoon-to-be, and the platoon-to-be determines the intelligent connected automatic driving vehicle fleet as the target vehicle fleet, and the number of vehicles in the target vehicle fleet is greater than or equal to the number of vehicles in the incorporated vehicle fleet;

[0068] The specific steps of the screening are as follows:

[0069] S3.1, screen all received requests, first screen the vehicle fleet with the number of incorporated vehicles equal to the remaining capacity of the target vehicle fleet, if there is, send an incorporated invitation and confirm that the vehicle fleet is the platoon-to-be, if not, screen the vehicle fleet with the number of incorporated vehicles greater than the remaining capacity of the target vehicle fleet;

[0070] S3.2, screening the platoon with the number of vehicles greater than the remaining capacity of the target platoon, if any, sending an invitation to the platoon with the least number of vehicles after splitting the platoon and confirming the new platoon split from the platoon as the to-be-platoon, if not, continue screening the platoon with the number of vehicles less than the remaining capacity of the target platoon;

[0071] S3.3, screening the platoon with the number of vehicles less than the remaining capacity of the target platoon, if any, sending an invitation to the platoon with the most number of vehicles and confirming the platoon as the to-be-platoon, if not, sending an invitation to the single request vehicle and determining it as the to-be-platoon.

[0072] S4, obtaining the driving information and road environment information of all vehicles within the communication radius of the target platoon and the platoon vehicle through the road side unit and the vehicle communication unit, and exchanging information through inter-vehicle communication;

[0073] The driving information and road environment information include: the spatial position of the target platoon and the platoon vehicle in the road, the platoon speed, the acceleration and deceleration, the speed and acceleration and deceleration of the front and rear vehicles, the driving situation and spatial position of the vehicles in the adjacent lane of the target platoon, the number of driving road lanes, the road line type, and the weather condition;

[0074] Wherein, according to the relationship between the obtained spatial position of the target platoon and the to-be-platoon or platoon, the platoon vehicle or platoon can be divided into front or rear of the target platoon, and the division is based on the target gap of the target platoon. The specific position of the platoon vehicle or platoon relative to the target platoon can be divided into six categories, i.e. distributed in front or rear of the target platoon in the same lane, in front or rear of the adjacent lane, in front or rear of the crossing lane;

[0075] S5, the to-be-platoon drives to the adjacent lane of the target platoon, accelerates or decelerates into the to-be-platoon area according to the driving information and road environment information, and realizes speed coordination through the speed management module;

[0076] The relative position of the target platoon and the to-be-platoon or platoon is different, and the way of entering the to-be-platoon area is different. The platoon vehicle or platoon distributed in front or rear of the target platoon in the same lane enters the to-be-platoon area by changing lane to the adjacent lane of the target platoon and then accelerating or decelerating; the platoon vehicle or platoon distributed in front or rear of the adjacent lane of the target platoon enters the to-be-platoon area by accelerating or decelerating; the platoon vehicle or platoon distributed in front or rear of the crossing lane of the target platoon enters the to-be-platoon area by changing lane to the adjacent lane of the target platoon and then accelerating or decelerating;

[0077] The to-be-compiled area is: taking the road center line as the horizontal axis and being perpendicular to the road center line as the vertical axis, when the horizontal coordinate of the target gap tail vehicle body position of the target vehicle team has the same horizontal coordinate value as the adjacent lane where the compiled vehicle or vehicle team is located, the position is called the to-be-compiled area; if the compilation is a small intelligent networked automatic driving vehicle team, the small intelligent networked automatic driving vehicle team should enter the to-be-compiled area completely;

[0078] The specific steps of realizing speed coordination through the speed management module are as follows:

[0079] S5.1, when there is no obstacle vehicle in front of the compiled vehicle or vehicle team and the target vehicle team, the following expression should be satisfied:

[0080] v in = v p

[0081] In the formula, v in is the required speed of the compiled vehicle or vehicle team, and v p is the speed of the target vehicle team;

[0082] S5.2, when there is an obstacle vehicle in front of the compiled vehicle or vehicle team and no obstacle vehicle in front of the target vehicle team, the following expression should be satisfied:

[0083]

[0084] In the formula, is the speed of the vehicle in front of the compiled vehicle or vehicle team;

[0085] S5.3, when there is no obstacle vehicle in front of the compiled vehicle or vehicle team and there is an obstacle vehicle in front of the target vehicle team, the following expression should be satisfied:

[0086]

[0087] In the formula, is the speed of the vehicle in front of the target vehicle team;

[0088] S5.4, when there are obstacle vehicles in front of the compiled vehicle or vehicle team and the target vehicle team, the following expression should be satisfied:

[0089]

[0090] S6, the target vehicle team tail vehicle expands the gap and compiles the vehicle team when the gap is sufficient to meet the conditions for safe compilation of the to-be-compiled vehicle team, if it is a small vehicle team, the small vehicle team is compiled from the tail of the small vehicle team in turn until the team is completed, and the specific expression is as follows:

[0091] And

[0092] In the formula, Longitudinal distance d between the target platoon gap rear vehicle and the platoonable vehicle in the platoonable region l-g Longitudinal distance d between the target platoon gap front vehicle and the platoonable vehicle in the platoonable region f-g Longitudinal safety distance between the target platoon gap rear vehicle and the platoonable vehicle in the platoonable region Longitudinal safety distance between the target platoon gap front vehicle and the platoonable vehicle in the platoonable region Gap rear vehicle speed v l -g Gap front vehicle speed v f-g Platoonable vehicle or platoon length l, platoonable vehicle or platoon speed v, connected and automated vehicle (CAV) reaction time Braking delay time t delay Minimum acceleration a min ;

[0093] Further, the widening target gap and controlling the platoonable vehicle or platoon into the target platoon is achieved by using a controller, which is composed of two parts, a lateral controller and a longitudinal controller, the lateral controller aims to minimize the lateral position error, and the longitudinal controller aims to minimize the gap error.

[0094] The controller is decomposed into lateral and longitudinal targets as follows:

[0095] Lateral target: CAVs in the platoonable vehicle or platoon change lanes in turn. The lateral target of the proposed controller is to minimize the lateral position error. The lateral position error is defined as follows:

[0096]

[0097] where y j is the lateral position of the jth CAV; is the lateral position of the centerline of the current lane initially, and when the target gap is sufficient for the jth vehicle to change lanes, is the lateral position of the centerline of the target lane.

[0098] Longitudinal target: Each CAV follows its adjacent rear CAV. Therefore, the longitudinal target of the proposed controller is to minimize the following gap error. The following gap error is defined as follows:

[0099]

[0100] where x j is the longitudinal position of the jth CAV; g des is the required following gap in the platoonable vehicle or platoon. The following gap includes the length of the vehicle.

[0101] The controller adopts a receding horizon control framework, as shown in Figure 3 The receding optimization optimizes the performance index at each time instant only involves a finite time from the time instant, while to the next time instant, the optimization time is pushed forward at the same time, and the online optimization is constantly carried out. A set of future control actions is obtained at each time instant, while only the control action at the current time is implemented, and a new set of controls is optimized by re-prediction at the next time instant, and only a new control action is implemented. Each step is feedback correction. The predictive control has foresight, and the receding optimization and feedback correction can better adapt to the actual system and have stronger robustness.

[0102] In each rolling step, the longitudinal planning trajectory is first calculated, and then passed to the lateral planning. Finally, the longitudinal and lateral commands are passed to the driving layer together.

[0103] In order to make the platoon follow the rear vehicle in the platoon to the target platoon in the platoon process, the state equation is used as a prediction model, and the state space is designed to be reversed. The state and control vectors of the controller are as follows:

[0104] When the platoon vehicle is a small platoon, the longitudinal state vector ξ x,n , the longitudinal control vector u x,n , the lateral state vector ξ y,n and the lateral control vector u y,n are defined as follows:

[0105]

[0106]

[0107] In the formula, v j is the speed of the jth CAV; x j is the longitudinal position of the jth CAV; g des is the required following gap; a j is the acceleration of the jth CAV; is the heading angle of the jth CAV; y j is the lateral position of the jth CAV; is the lateral position of the center line of the current lane, and when the target gap is sufficient to meet the lane change of the jth vehicle, is the lateral position of the center line of the target lane. is the angle of the front wheel of the jth CAV.

[0108] In order to make the platoon have stability, the state space representation is made to keep the form of queue length propagation consistent, based on a two-degree-of-freedom model of CAV longitudinal position and CAV lateral position, as shown in Figure 4The dynamics model of the CACC system is established as shown below:

[0109]

[0110] Bringing it into the longitudinal and lateral decoupling CACC dynamics model is formulated as follows:

[0111]

[0112] where,

[0113] κ is the road curvature.

[0114] To speed up the calculation, the controller aims to minimize the total state cost within the control range. The running cost L is composed of state cost and control cost. By adjusting the weighting factors, a balance can be achieved between the following stability and control force minimization, which is expressed as follows:

[0115]

[0116] where, J x and J y are the longitudinal and lateral costs, respectively; τ is the control time domain; Q x,n , R x,n , Q y,n , R y,n are all non-negative weighting matrices. They are composed of weighting factors, including the speed error weighting factor q ν , the gap error weighting factor q g , the acceleration weighting coefficient r a , the heading angle weighting coefficient the lateral position error weighting coefficient q y , and the front wheel angle weighting coefficient r δ . By adjusting these weight factors, different driving goals can be achieved, and I is the unit matrix.

[0117] The controller is limited by anti-collision, required speed range, geometric boundary, acceleration ability, and yaw angle constraints. Anti-collision within the vehicle platoon is achieved by adjusting the inter-vehicle gap, as follows:

[0118]

[0119] Here, is the safe following gap in the CACC platoon;

[0120] Front and rear anti-collision ensure anti-collision between vehicle platoons, as follows:

[0121]

[0122] where x f-P is the longitudinal position of the leading vehicle in the platoon; x l-P is the longitudinal position of the following vehicle in the platoon, is the safe following gap between CAVs;

[0123] The vehicle should be within the road geometry boundaries, expressed as:

[0124] y min ≤ y ≤ y max

[0125] The acceleration should be limited by the vehicle performance and comfort:

[0126] a min ≤ a ≤ a max

[0127] The front wheel angle of the vehicle should be within its steering range:

[0128] δ fmin ≤ δ f ≤ aδ fmax

[0129] The parameters configured to the controller are as follows:

[0130] Table 1. Controller parameter configuration

[0131]

[0132]

Claims

1. A control method for enhancing the CAV platooning strength in mixed traffic flow under vehicle-road collaboration, characterized by: The following steps are involved: S1. The intelligent connected autonomous driving fleet publishes the remaining capacity of the fleet to all intelligent connected autonomous driving vehicles or small intelligent connected autonomous driving fleets within the fleet communication radius; S2. An intelligent connected autonomous vehicle or a small intelligent connected autonomous vehicle fleet that needs to form a platoon sends a platooning request to the intelligent connected autonomous vehicle fleet and determines the number of vehicles that can be included; S3: After screening, the intelligent connected autonomous driving fleet invites the intelligent connected autonomous driving vehicle or small intelligent connected autonomous driving fleet that has made the request as a fleet to be organized. The fleet to be organized determines the intelligent connected autonomous driving fleet as the target fleet. S4. Obtain driving information and road environment information of all vehicles within the communication radius of the target convoy and the assigned vehicles through the roadside unit and the vehicle communication unit, and exchange information through vehicle-to-vehicle communication; S5: The convoy to be organized drives to the adjacent lane of the target convoy, accelerates or decelerates according to driving information and road environment information to enter the area to be organized, and achieves speed coordination through the speed management module; S6. The rear vehicle of the target convoy slows down to widen the gap. When the gap is large enough to allow the convoy to be safely incorporated, the vehicle is incorporated into the convoy.

2. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The remaining capacity of the fleet is the number of vehicles that can be incorporated into the fleet, and the number of vehicles that can be incorporated into the fleet is equal to the difference between the number of vehicles in the maximum fleet formation length and the current number of vehicles in the fleet.

3. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The specific circumstances in which the intelligent connected autonomous driving vehicle or small intelligent connected autonomous driving fleet with platooning requirements sends a platooning request to the intelligent connected autonomous driving fleet and determines the number of vehicles that can be incorporated are divided into the following two situations: When the remaining capacity of the fleet is greater than or equal to that of the small intelligent connected autonomous driving fleet, all small intelligent connected autonomous driving fleets will be used as fleets to be organized; When the remaining capacity of the fleet is less than that of the small intelligent connected autonomous driving fleet, the small intelligent connected autonomous driving fleet will be split.

4. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 3 is characterized by: The small intelligent connected autonomous driving fleet is half or less of the number of vehicles in the maximum formation length; The splitting principle is: split from the front or rear of the small fleet based on the relative position of the target fleet and the small intelligent connected autonomous driving fleet. The number of split vehicles is the remaining capacity of the fleet, or the target fleet invites other vehicles or fleets as included vehicles.

5. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: After screening, the intelligent connected autonomous driving fleet invites the intelligent connected autonomous driving vehicle or small intelligent connected autonomous driving fleet that has made the request as a fleet to be organized. The fleet to be organized determines the intelligent connected autonomous driving fleet as a target fleet, wherein the number of vehicles in the target fleet is greater than or equal to the number of vehicles in the to-be-organized fleet. The specific steps of the screening are as follows: S3.

1. Screen all received requests, first screening teams whose number of vehicles to be incorporated equals the remaining capacity of the target fleet. If so, send them an invitation to be incorporated and confirm them as the team to be incorporated. If not, screen teams whose number of vehicles to be incorporated exceeds the remaining capacity of the target fleet. S3.

2. Screen teams whose number of vehicles to be incorporated into the fleet is greater than the remaining capacity of the target fleet. If so, invite the team with the fewest remaining vehicles after splitting the incorporated vehicles and confirm the new fleet split from that team as the fleet to be incorporated. If not, continue screening teams whose number of vehicles to be incorporated into the fleet is less than the remaining capacity of the target fleet. S3.

3. Screen the fleets whose number of vehicles to be incorporated into the fleet is less than the remaining capacity of the target fleet. If there are fleets, send an invitation to incorporate to the fleet with the largest number of vehicles and confirm that fleet as the fleet to be incorporated into. If there are no fleets to be incorporated into, send an invitation to incorporate to the single vehicle that made the request and confirm that it is the vehicle to be incorporated into.

6. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The driving information and road environment information include: the spatial position of the target convoy and the vehicles being organized on the road, the formation speed, acceleration and deceleration, the speed and acceleration and deceleration of the vehicles in front and behind, the driving conditions and spatial position of the vehicles in the adjacent lanes of the target convoy, the number of lanes on the road, the road line type, and the weather conditions.

7. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The area to be organized is: with the center line of the road as the horizontal axis and the vertical axis perpendicular to the center line of the road. When the horizontal coordinate of the vehicle body position at the tail end of the target gap of the target fleet has the same horizontal coordinate value as the adjacent lane where the incorporated vehicle or fleet is located, the position is called the area to be organized; if it is incorporated into a small intelligent connected autonomous driving fleet, the small intelligent connected autonomous driving fleet should completely enter the area to be organized.

8. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The specific steps of implementing speed coordination through the speed management module are as follows: S5.

1. When there are no obstacles in front of the incoming vehicle or convoy and the target convoy, the following expression shall be satisfied: v in =v p Where, v in The speed required to join a vehicle or convoy, v p is the target convoy speed; S5.

2. When there is an obstructing vehicle ahead of the incoming vehicle or convoy, and there is no obstructing vehicle ahead of the target convoy, the following expression shall be satisfied: Where, Speed ​​of the vehicle being incorporated or the preceding vehicle in the convoy; S5.3 When there is no obstacle in front of the incoming vehicle or convoy, and there is an obstacle in front of the target convoy, the following expression should be satisfied: Where, is the speed of the leading vehicle in the target convoy; S5.

4. When there are obstacles ahead of both the incoming vehicle or convoy and the target convoy, the following expression should be satisfied:

9. The control method for enhancing CAV platoon formation strength in mixed traffic flow under vehicle-road collaboration according to claim 1 is characterized by: The tail vehicle of the target convoy slows down to widen the gap, and when the gap is large enough to meet the conditions for safe inclusion of the convoy, the vehicle is incorporated into the convoy. The specific expression is as follows: Where, The longitudinal distance d between the target platoon's rear vehicle and the vehicles to be assembled in the area to be assembled l-g , the longitudinal distance d between the front vehicle of the target platoon and the vehicles to be assembled in the area to be assembled f-g , the longitudinal safety distance between the target convoy’s rear vehicle and the vehicles to be assembled in the area to be assembled The longitudinal safety distance between the front vehicle in the target convoy and the vehicles to be assembled in the area to be assembled Gap rear vehicle speed Gap front vehicle speed The length of the convoy or vehicle l, the speed of the vehicle or convoy v, and the reaction time of the intelligent connected autonomous driving vehicle Braking delay time t delay , minimum acceleration a min .

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