Highway ramp intelligent connected vehicle merging optimization method considering influence of large truck

Abstract

The application relates to the technical field of traffic flow merging control, and discloses a highway ramp intelligent networked vehicle merging optimization method considering the influence of large trucks. The method comprises the following steps: dividing an upstream area of a merging point into a main line vehicle adjustment area and a merging area, wherein the main line vehicle adjustment area is further divided into a lane changing area and a platoon area; guiding part of the main line vehicles to change lanes and branch off in the lane changing area based on safety gaps and speed constraints, so as to create merging space for ramp vehicles; controlling the vehicles on the remaining outer lane to form vehicle platoons in the platoon area; and according to the state information of the vehicle platoons and the ramp incoming vehicles in the merging area, an improved estimated arrival time algorithm is used to optimize the merging sequence of the main line vehicle platoons and the ramp incoming vehicles, and the speed trajectory of the vehicle merging process is energy-saving optimized. Through vehicle platoon cooperation and fine control of heterogeneous vehicles, the intelligent vehicles can be cooperatively, efficiently and energy-savingly merged in the highway ramp merging area.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous traffic flow merging control technology, specifically to an intelligent connected vehicle merging optimization method for highway ramps that takes into account the impact of large trucks. Background Technology

[0002] Traditional ramp control methods (such as the ALINEA algorithm and variable speed limit control) mainly rely on infrastructure such as traffic signals and loop detectors to regulate traffic flow at a macro level. These methods have inherent limitations, including long control cycles, low accuracy, and difficulty in responding to dynamic traffic demands. Connected and Autonomous Vehicles (CAV) technology is considered an effective way to alleviate these problems. It acquires high-precision traffic status data in real time through vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication, while cloud-based decisions are directly delivered to individual vehicles, laying a solid foundation for precise and coordinated vehicle-level control.

[0003] However, existing research on CAV-based ramp merging control mainly focuses on two aspects: firstly, vehicle merging trajectory optimization, which uses methods such as optimal control and model predictive control to optimize the acceleration and velocity curves of individual vehicles to achieve smooth, safe, and efficient merging; secondly, vehicle merging sequence optimization, which uses rule-based (e.g., FIFO) or optimization-based (e.g., mixed-integer linear programming, MILP) methods to determine the order in which vehicles pass through the merging zone to reduce conflicts. In-depth analysis reveals that existing technologies still have the following significant shortcomings:

[0004] First, most studies assume that traffic flow consists of discrete, independent vehicles, neglecting the common phenomenon of "vehicle platoons" that naturally or collaboratively form in highway mainline traffic flow. Vehicle platooning is characterized by stable spacing and coordinated speed regulation. Treating it as a unified control unit rather than multiple independent vehicles can greatly simplify the complexity of merging decisions and improve merging efficiency. Existing research has failed to fully utilize this characteristic of platoons, or has only performed simple grouping, without exploring in depth platoon formation, intra-platoon coordination, and dynamic interaction with on-ramp vehicles to optimize merging sequences.

[0005] Secondly, in terms of merging sequence optimization, existing strategies are mostly designed for single-type intelligent connected vehicles (passenger cars). There is a lack of specific consideration for intelligent connected large trucks, an important component of transportation. Large trucks differ significantly from passenger cars in terms of dynamic performance (such as acceleration / deceleration capabilities and vehicle length) and their impact on traffic flow stability. Ignoring the heterogeneity of trucks, especially when they participate in or interfere with vehicle platooning, directly applying control strategies based on passenger cars may lead to infeasible control commands, platoon instability, and even safety accidents, severely limiting the practical application of existing methods.

[0006] Furthermore, in terms of scenarios, existing merging control research is mostly limited to single-lane mainline scenarios, which oversimplifies the situation and fails to fully reproduce and effectively utilize the multi-lane resources of the mainline. In simplified single-lane scenarios, the merging of vehicles from ramps creates significant traffic pressure downstream of the outer lanes. How to optimize the merging sequence and provide corresponding speed guidance while making full use of the inner lanes for flow distribution, in order to alleviate congestion downstream of the merging zone, is a direction that has not yet been fully explored.

[0007] Therefore, there is an urgent need for a new type of collaborative control strategy that can fully consider the operating characteristics of vehicle platoons, accommodate the heterogeneous traffic flow challenges brought by large trucks, and perform globally optimized merging sequence decision-making and speed planning in multi-lane environments. This would improve the traffic efficiency, safety, and energy economy of highway merging zones from a more realistic and feasible perspective. Summary of the Invention

[0008] To address the aforementioned shortcomings in the existing technology, this invention provides a method for optimizing the merging of intelligent connected vehicles on highway ramps, taking into account the impact of large trucks.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0010] A method for optimizing the merging of intelligent connected vehicles on highway ramps, taking into account the impact of large trucks, includes the following steps:

[0011] The area upstream of the merging point is divided into the mainline vehicle adjustment area and the merging area. The mainline vehicle adjustment area is further subdivided into the lane-changing area and the formation area, and the lengths of the mainline vehicle lane-changing area and the formation area are determined.

[0012] Coordinated control of mainline vehicles within the mainline vehicle adjustment zone; the coordinated control includes: guiding some mainline vehicles to change lanes and divert in the lane-changing zone based on safety gaps and speed constraints, creating merging space for ramp vehicles; and controlling vehicles in the remaining outer lanes to form a vehicle queue in the platooning zone.

[0013] Within the merging zone, based on the status information of the vehicle queue and the approaching vehicles on the ramps, and taking into account the heterogeneous characteristics of large trucks and passenger cars, an improved estimated arrival time calculation method is used to determine the merging sequence and merging speed of the mainline vehicles and the ramp vehicles.

[0014] Based on the determined merging sequence and merging velocity, energy-saving optimization is performed on the acceleration curves of each vehicle within the merging zone.

[0015] The present invention has the following beneficial effects:

[0016] This invention first re-divides the traditional ramp merging area into two core functional areas: a mainline vehicle adjustment area and a merging area. The mainline vehicle adjustment area is further subdivided into a lane-changing area and a platooning area. In the lane-changing area, lane-changing control based on safety gaps and speed constraints is implemented to achieve vehicle diversion on the two mainline lanes, creating space for ramp vehicles to merge into the mainline. In the platooning area, a critical distance determination method is used to enable vehicles to actively approach and form a platoon. In the merging area, an improved estimated arrival time calculation method is used to optimize the merging sequence of the arriving platoons and energy-saving optimization is performed on the vehicle acceleration curve during the merging process. Ultimately, this invention achieves coordinated, efficient, and energy-saving merging of mainline vehicles and ramp vehicles. Attached Figure Description

[0017] Figure 1 A schematic diagram of a method for optimizing the merging of intelligent connected vehicles on highway ramps, taking into account the impact of large trucks.

[0018] Figure 2 This is a schematic diagram of the merging area of ​​the ramps;

[0019] Figure 3 A schematic diagram of the research scenario;

[0020] Figure 4 This is a schematic diagram of the regional division scheme;

[0021] Figure 5 This is a diagram showing the vehicle positions in the lane-changing area;

[0022] Figure 6 This is a diagram illustrating the following behavior of adjacent vehicles.

[0023] Figure 7 A motion diagram illustrating the process of convoy formation;

[0024] Figure 8 A diagram illustrating the fleet status for different vehicle models;

[0025] Figure 9 Determine the flow chart for vehicle merging sequences under different vehicle models. Detailed Implementation

[0026] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0027] like Figure 1As shown, an embodiment of the present invention provides a method for optimizing the merging of intelligent connected vehicles on highway ramps, taking into account the impact of large trucks, comprising the following steps S1 to S4:

[0028] S1. Divide the area upstream of the merging point into a mainline vehicle adjustment area and a merging area. The mainline vehicle adjustment area is further subdivided into a lane-changing area and a platooning area, and the lengths of the mainline vehicle lane-changing area and platooning area are determined.

[0029] In an optional embodiment of the present invention, the basic functions of a highway ramp entrance area are illustrated as follows: Figure 2 As shown, the ramp merging area can be divided into an entrance area, a ramp area, a mainline area, and a transition area. Due to the disorderly merging of vehicles, the ramp merging area often faces congestion and collisions when traffic volume is high. In order to alleviate congestion in the merging area and improve the traffic efficiency of vehicles in the merging area, this invention divides the entire coordinated merging control process into two areas: the mainline vehicle adjustment area and the merging area.

[0030] like Figure 3 As shown, this invention takes the merging zone of a highway entrance ramp with two lanes on the main line and one lane on the ramp as the research scenario. The main line and the ramp are connected by parallel acceleration lanes, and the merging point is located at the end of the acceleration lane. All vehicles merge at the merging point. The main line vehicle adjustment zone is divided into two parts: a lane-changing zone and a platooning zone. Vehicles in the outer lanes of the main line change lanes when the lane-changing conditions are met; vehicles that do not change lanes enter the platooning zone to form a platoon. Main line platoons entering the merging zone are not allowed to change lanes within the merging zone according to actual traffic planning, and are assigned a merging order along with ramp vehicles entering the merging zone. Furthermore, the lead vehicle and ramp vehicles in the main line platoon within the merging zone plan their merging trajectories using an optimized scheme that balances efficiency and energy consumption. Following vehicles in the platoon closely follow the vehicle in front according to the CACC (Cooperative Adaptive Cruise Control) following model. After completing the merging and exiting the cooperative merging control zone, vehicle control is cancelled.

[0031] To achieve the above control, the vehicle-road communication architecture is designed as follows: Figure 4 As shown, in an intelligent connected environment, vehicle information and current traffic conditions within each area can be shared through the On-Board Unit (OBU) and Roadside Unit (RSU). After a vehicle enters the control area, the central controller collects its vehicle information and surrounding road environment information, and then issues different instructions to the vehicle according to the implementation conditions of each area's control. In an intelligent connected environment, all vehicles entering the control area are connected via short-range communication, managed by the cloud-based ramp merging central controller, and strictly obey the controller's commands.

[0032] The specific details regarding the division of each region and its length arrangement are as follows:

[0033] Mainline vehicle adjustment area: The mainline vehicle adjustment area is located on the upstream section of the mainline in the ramp merging area, and is divided into lane changing area and formation area.

[0034] (1) Lane changing area

[0035] The lane-changing zone includes the inner and outer lanes of the highway. Within the lane-changing zone, the central controller analyzes whether the vehicle meets the gap and speed requirements for lane changing and sends the lane-changing instruction to the vehicle through the roadside facilities. The vehicle that needs to change lanes will perform the lane-changing operation according to the received instruction. Within this zone, only vehicles in the outer lane are allowed to change to the inner lane.

[0036] This invention primarily considers the safe lane-changing distance for vehicles. The lane-changing zone should be long enough to ensure a safe distance is maintained between the lane-changing vehicle and the vehicles in front and behind in the target lane. When a vehicle needs to change lanes, a safe distance must be maintained with both the vehicle in front and behind in the target lane. Assuming the lane-changing zone can guarantee that at least one vehicle will perform a lane-changing operation at any given time, the length L of the lane-changing zone is... oc Should meet:

[0037]

[0038] in, To ensure a safe following distance when vehicles change lanes, This is the maximum speed limit for the main road of the highway. The reaction time of a vehicle after receiving lane change information. This refers to the length of the vehicle.

[0039] (2) Formation area

[0040] The platooning zone is located downstream of and connects to the lane-changing zone, but it only groups vehicles in the outer lanes of the mainline. Vehicles in this zone are not allowed to change lanes. After a vehicle in the outer lane leaves the lane-changing zone and enters the platooning zone, the central controller first determines whether the vehicle will become a lead or follower, and then issues instructions according to different speed control methods. The vehicles then form a platoon safely and efficiently before leaving the platooning zone. Within the platooning zone, vehicles not only form a convoy according to instructions, but also adjust their speeds to ensure the convoy enters the merging zone at the same speed, ensuring a stable merging for subsequent vehicles.

[0041] The length of the formation zone depends on various factors, including vehicle length, safe distance between vehicles, and formation speed. The formation zone should be long enough to accommodate the entire convoy while ensuring safe distances between vehicles and taking into account safety during acceleration and deceleration. The formation strategy of this invention considers the process of vehicles forming a convoy; therefore, the length of the formation zone is estimated using a two-vehicle group as an example. To ensure that at least one convoy's lead vehicle can adjust to the design speed of the main lane within the formation zone, following vehicles adjust to the design speed of the main lane within the zone and join the convoy. The length of the formation zone... The following conditions must be met:

[0042]

[0043]

[0044] in, Design speed for the main lanes of the expressway. , These represent the speeds of the vehicles designated as the lead car and the following cars when they enter the formation area. This is the vehicle's maximum acceleration. To ensure a safe following distance for the convoy.

[0045] (3) Merging Zone: The merging zone connects to the mainline vehicle adjustment zone and ends at the end of the transition area where the ramp intersects with the mainline. It includes a small portion of the mainline area, a small portion of the ramp area, the acceleration lane, and the merging transition area. The merging zone only considers the merging process of the ramp and the outer mainline lane. Therefore, vehicles on the mainline lane are not allowed to change lanes. Within the merging zone, the central controller will acquire and optimize the vehicle's speed and acceleration every second. The speed and acceleration of all vehicles in the area for the next second will be transmitted to each vehicle through the roadside facilities until the vehicle leaves the merging zone at the merging speed. This aims to enable the ramp and mainline vehicles to merge in a low-energy and high-efficiency manner while ensuring safety.

[0046] The merging strategy at the entrance ramp in this invention is divided into two parts: mainline vehicles perform two operations in the adjustment zone: early lane changing and forming a platoon; and entrance ramp vehicles cooperate with the mainline platoon in the merging zone.

[0047] S2. Coordinated control of mainline vehicles within the mainline vehicle adjustment zone; the coordinated control includes: guiding some mainline vehicles to change lanes and divert in the lane-changing zone based on safety gaps and speed constraints, creating merging space for ramp vehicles; and controlling vehicles in the remaining outer lanes to form a vehicle queue in the queuing zone.

[0048] In an optional embodiment of the present invention, guiding some mainline vehicles to change lanes and divert traffic in the lane-changing area based on safety clearances and speed constraints includes:

[0049] The headway between the current vehicle and the vehicles in front and behind in adjacent lanes is determined based on the vehicle information and movement status of intelligent connected vehicles and intelligent connected trucks.

[0050] The absolute safe following distance for intelligent connected vehicles and the safe lane-changing distance for intelligent connected trucks are determined based on the vehicle information and movement status of intelligent connected vehicles and intelligent connected trucks, respectively.

[0051] The absolute safe headway for a vehicle to change lanes is determined by the larger of the absolute safe following distance and the safe lane-changing distance.

[0052] Determine whether the headway between the current vehicle and the vehicles in front and behind in the adjacent lane is greater than the absolute safe headway for the vehicle to change lanes; if so, proceed to the next step; otherwise, do not control the current vehicle to change lanes.

[0053] Determine if the current vehicle's speed meets the speed range of the vehicles in front and behind in the target lane; if so, control the current vehicle to change lanes; otherwise, do not control the current vehicle to change lanes.

[0054] The absolute safe following distance for intelligent connected vehicles is determined based on their vehicle information and movement status, specifically as follows:

[0055]

[0056] Where S represents the absolute safe following distance. It is the sum of the reaction distance and braking distance of the following vehicle. For safe parking distance, This is the braking distance of the vehicle in front. The speed of the car in front. For the speed of the following vehicle, For driver reaction time, For the reaction time of braking operation of intelligent connected vehicles, This is the vehicle's maximum acceleration.

[0057] The safe lane-changing distance for intelligent connected trucks is determined based on their vehicle information and movement status, specifically as follows:

[0058]

[0059] Where D represents the lane-changing safety distance. For the speed of intelligent connected trucks, The reaction time for braking operations of intelligent connected trucks. It is the acceleration due to gravity. The coefficient of friction of the road. The slope of the road. This refers to the vehicle's length.

[0060] Within the merging zone of highway entrance ramps, vehicles are forced to merge into the main road traffic flow due to the road environment they face. When the main road traffic volume is high, the slow lane-changing behavior of ramp vehicles waiting for a suitable lane-changing gap can cause traffic congestion, leading to a decrease in merging efficiency.

[0061] In a scenario where a mainline two-lane ramp merges with an inner lane, the mainline traffic flow is divided into outer and inner lanes. Typically, mainline vehicles are not allowed to change lanes within the merging zone. When ramp traffic flows into the outer lane, vehicles in the outer lane need to adjust their distance from the ramp vehicles and decelerate or accelerate to accommodate the newly joined vehicles. If the ramp traffic volume is high and the outer lanes cannot effectively create space to accommodate these new vehicles, traffic congestion may occur. This can prolong travel time and negatively impact the overall traffic flow.

[0062] Therefore, for a single-lane, two-way highway, the inner lane can be used to alleviate congestion on the outer lane caused by merging vehicles from ramps. Some vehicles on the outer lane change lanes in advance before entering the merging zone to create merging gaps for ramp vehicles merging into the main line. This also balances traffic flow on both the inner and outer lanes downstream of the merging zone, reducing the impact of ramp merging on upstream traffic. Therefore, this invention establishes a mainline vehicle adjustment zone before vehicles reach the merging zone. Within this adjustment zone, in the lane-changing area, vehicles on the outer lane that meet the lane-changing requirements move to the inner lane in advance, creating a larger merging gap for ramp vehicles.

[0063] When a vehicle changes lanes, both time and space conditions are required, namely, the timing of the lane change and a suitable lane-changing gap. The core issue of lane changing is finding a suitable lane-changing gap in the target lane; that is, the target lane should have sufficient driving space for the vehicle to complete the lane change. This mainly depends on the speeds of vehicles in front and behind in the target lane and the driver's ability to predict driving space. For example... Figure 5 As shown, when a vehicle arrives in the inner or outer lane of the lane-changing area, it is determined whether the required lane-changing distance and speed are met between the vehicle and the vehicles in front and behind in the adjacent lane. If a vehicle (blue vehicle) meets the lane-changing conditions, the vehicle will change lanes.

[0064] When changing lanes, if the speed of the vehicle changing lanes is too high (or low) or the target clearance is estimated unreasonably, the lane change may lead to a rear-end collision or lateral collision with a vehicle in the target lane. Therefore, vehicles changing lanes must meet certain speed requirements, and the target clearance must meet the lane change requirements to allow the vehicle to safely merge into the target lane. The steps for determining the safe lane change clearance in this invention are as follows: When the outer vehicle arrives at the lane change area, the adjacent vehicles in front and behind are found in the inner lane. At this time, the headway between the front vehicle and the adjacent vehicles in front and behind can be calculated by the following formula:

[0065]

[0066]

[0067] In the formula: , These are the headway distances between the vehicle changing lanes and the vehicles in front and behind in the target lane, respectively. The location of vehicles changing lanes; , These are the positions of the vehicles in front of and behind the target lane for the lane-changing vehicle; This refers to the length of the vehicle body; , The first , On the road The speed of the vehicle; This is the absolutely safe headway for a vehicle to change lanes. To ensure that a collision will not occur due to insufficient headway after the vehicle enters the target lane, it needs to be compared with the absolutely safe headway, i.e., it must satisfy:

[0068]

[0069] The absolute safe headway is obtained by analyzing the following behavior of adjacent vehicles. Figure 6 This diagram illustrates the following behavior of adjacent vehicles. To prevent a rear-end collision between vehicle F0 and vehicle L0 caused by the sudden stopping or significant deceleration of vehicle L0 during normal driving, vehicles must maintain a safe following distance S from the vehicle in front, as shown below:

[0070]

[0071]

[0072] in, This is the braking distance of the vehicle in front. It is the sum of the reaction distance and braking distance of the following vehicle. For safe parking distance, , These represent the speeds of the vehicle in front and the vehicle behind, respectively. For driver reaction time (when the vehicle is an intelligent connected autonomous driving vehicle), ), The reaction time for vehicle braking operation. This is the vehicle's maximum acceleration. This refers to the vehicle's length.

[0073] Once the vehicle clearance condition is met, in order to ensure the speed safety of lane changing and prevent rear-end collisions due to speed differences, the speed difference requirement between the current vehicle and the vehicles in front and behind in the target lane must also be met. The speed constraints between vehicles are as follows:

[0074]

[0075] Only vehicles that meet the lane-changing safety clearance and speed constraints can perform lane-changing operations.

[0076] Studies on ramp merging typically focus on homogeneous passenger cars. However, with ever-increasing logistics demands and freight volume, the impact on traffic flow is gradually growing. Therefore, it is essential to study ramp merging involving large trucks. This embodiment, based on the vehicle control strategy within the aforementioned merging section, modifies and refines the vehicle speed control method within the control section, establishing a queue merging model that considers the influence of trucks.

[0077] In most countries and regions, highway driving rules generally require all vehicles to stay in the rightmost lane unless overtaking or changing lanes due to road conditions (such as entrances / exits). This rule is particularly important for large trucks, as they typically travel slower than passenger cars and have poorer acceleration and deceleration. Therefore, trucks on highways usually travel in the rightmost lane or lanes designated for slower vehicles to minimize their impact on fast-moving traffic and improve overall road safety and flow. In rare cases, trucks may also choose to change lanes to reduce vehicle conflicts and alleviate traffic congestion, such as at merging areas.

[0078] Similar to the lane-changing zone control strategy described above, large trucks intending to change lanes must meet absolute safety headway constraints and speed constraints before entering the advance lane-changing zone to initiate a lane-changing action. In addition, large trucks must also consider the safe lane-changing distance. The safe lane-changing distance for trucks is typically determined by several factors, including the truck's speed, braking performance, acceleration capability, and road conditions. A common method is to estimate the safe distance based on the two-second rule, meaning that at any speed, the driver should maintain a distance of at least two seconds from the vehicle in front. However, for heavy trucks, given the differences in acceleration and deceleration performance compared to passenger cars, a longer time interval may be necessary to ensure safety.

[0079]

[0080] Where: D is the lane-changing safety distance. It's the speed of the truck. This refers to reaction time. For trucks, this time may be longer, typically taken as 2 to 2.5 seconds, considering the time it takes for the driver to perceive a hazard and begin braking. It is gravitational acceleration. This is the coefficient of friction of a road surface, which depends on road conditions. For example, the coefficient for dry asphalt is approximately 0.7 to 0.8. It represents the road's gradient; uphill slopes are represented by positive values, and downhill slopes by negative values. The formula takes into account factors such as vehicle reaction time, braking distance, and vehicle length. The safe lane-changing distance D is compared with the absolute safe following distance S calculated in the previous part. The safe distance that needs to be guaranteed is the larger of the two.

[0081] In an optional embodiment of the invention, controlling the formation of a vehicle queue in the remaining outer lanes within the queuing area includes:

[0082] A1. Determine if the current vehicle entering the formation area is the same model as the vehicle in front; if so, proceed to step A2; otherwise, form the current vehicle into the formation according to the speed control of the lead vehicle.

[0083] A2. Calculate the current distance and critical distance between the current vehicle and the vehicle in front;

[0084] A3. Determine if the current distance between the current vehicle and the vehicle in front is greater than the critical distance; if so, assemble the current vehicles according to the speed control of the lead vehicle; otherwise, proceed to step A4.

[0085] A4. Determine if the convoy size of the preceding vehicle has reached the maximum convoy size; if so, then convoy the current vehicle according to the speed control of the lead vehicle; otherwise, convoy the current vehicle according to the speed control of the following vehicles.

[0086] The purpose of the merging zone is to enable eligible vehicles to proactively form a stable convoy before entering the merging area. This model optimizes the distance and speed between vehicles, maximizing the use of road space and achieving safe and efficient vehicle flow.

[0087] The main idea of ​​this invention's platooning strategy is to find the critical distance between two vehicles to form a platoon without reducing the passage efficiency of the preceding vehicle. Specifically, it determines a vehicle's role as either the lead or follower by judging whether it can catch up with the preceding vehicle and join the platoon. Within the platooning zone, vehicles in the outer lanes that have not changed lanes are sequentially assessed to see if they meet the conditions for joining the preceding platoon. If they do, they become followers of the preceding vehicle; otherwise, they become the lead vehicle in the new platoon.

[0088] In an intelligent connected vehicle environment, when vehicles enter a platooning area, they will form a convoy with other vehicles of the same model that may be present in front or behind. In this scenario, large trucks only consider forming platoons with other large trucks, and passenger cars only consider forming platoons with other passenger cars. The main differences between truck platooning and passenger car platooning lie in their purpose, composition, and operational characteristics. Truck platooning typically consists of multiple heavy-duty trucks, primarily aimed at improving the efficiency and safety of logistics transportation by reducing fuel consumption through reduced air resistance. In contrast, passenger car platooning is more commonly seen in the testing of autonomous driving technologies, focusing on increasing driving modes and improving road safety. Truck platooning requires longer safety distances and longer reaction times for lane changes and braking, while passenger car platooning offers greater flexibility and demands closer coordination and reaction speed among its members.

[0089] This embodiment considers the platooning rules that take into account the impact of large trucks. The main difference lies in the determination of vehicle type and the different safety distances and acceleration / deceleration considerations for truck platooning. The steps are as follows:

[0090] Step 1: Determine if the model of the car in front is the same as that of the car in front.

[0091] When a vehicle enters the platooning area, the vehicle is assessed. If the vehicle entering the control area is the same model as the vehicle in front, proceed to step 2; otherwise, proceed to step 3.

[0092] Step 2: Calculate the critical distance between the two vehicles to form a convoy.

[0093] Calculate the current distance between this vehicle and the vehicle in front. and critical spacing Each CAV entering the formation zone has an initial speed. At this point, the distance between the CAV and the preceding CAV, as well as their respective speeds, become the determining factors for whether a platoon can form. The critical distance is defined as the maximum initial distance at which a platoon can form if the real-time distance between the two CAVs is less than this distance. This ensures that the following CAV can form a platoon with the preceding CAV at the instant it enters the formation zone. Therefore, this critical distance must be less than the length of the formation zone and is not a fixed value but varies with vehicle speed. To investigate the maximum initial distance between the preceding and following CAVs entering the formation zone, different scenarios were considered. It was found that the following CAV accelerates to its maximum speed at the end of the formation zone... The following vehicle began accelerating as it entered the formation area. and with When chasing the vehicle in front at a constant speed, the initial distance between the two vehicles within the formation zone is the greatest. Based on the motion process, a motion state diagram and a velocity trajectory diagram can be drawn. Figure 7It shows the state of the vehicles as they enter the formation area and as they form a convoy.

[0094] make This is the acceleration phase for the following vehicle (0~t1). This is the period when both vehicles are moving at a constant speed (t1~t2). This is the acceleration phase of the preceding vehicle (t2~t3). The critical distance at which vehicles can form a platoon. The calculation formula is:

[0095]

[0096] in, , , for exist , , The distance traveled within the area; , , for exist , , The distance traveled within the area; , for , The distance traveled during the formation of the convoy; , for Speeds of the two vehicles upon entering the formation area; This refers to the vehicle's maximum speed. This is the vehicle's maximum acceleration; The safe headway when vehicles are traveling in a convoy; The safe headway between vehicles when they are traveling in a convoy; This refers to the vehicle's length.

[0097] It should be noted that when calculating the critical distance, the maximum acceleration and deceleration and safe following distance of large trucks are different from those of passenger cars. The critical distance when vehicles enter the formation area at different times and at different speeds is also different. This distance represents the maximum distance that vehicles can catch up with the formation, and it is related to the length of the formation area. After the calculation is completed, proceed to step 3.

[0098] Step 3: Determining the lead vehicle and following vehicles.

[0099] When the vehicle's queue is still unknown The distance between vehicles is defined by the following formula:

[0100]

[0101] In the formula, and They represent time and the car in front The location.

[0102] This embodiment uses a critical distance setting as a distance condition to prevent excessive speed and acceleration when a vehicle far ahead forces its way into the platoon. When a vehicle enters the formation area, the real-time distance between that vehicle and the vehicle in front is calculated. and critical spacing If the calculation result is This indicates that the distance between the two vehicles is greater than the critical distance, and the vehicle cannot catch up with the vehicle in front within the formation zone. In this case, the vehicle is not considered to join the convoy ahead and is instead treated as the lead vehicle. If the calculation result is... Vehicles can catch up with the vehicle in front within the formation zone and join the convoy, becoming the following vehicle. Furthermore, if the number of vehicles in the convoy in the previous round has reached the maximum convoy size, that vehicle is designated as the lead vehicle for the new round. Proceed to step 4.

[0103] Step 4: Speed ​​planning for vehicles to form a convoy.

[0104] When the length of the formation zone is fixed, the furthest point at which the following vehicle can catch up with the preceding vehicle is also determined. The leading vehicle travels the shortest distance when accelerating to its maximum speed at the end of the formation zone. At this point, if the following vehicle accelerates to its maximum speed from the moment it enters the formation zone and maintains a constant maximum speed to catch up with the preceding vehicle, the initial distance between the two vehicles is the greatest. This situation represents the critical condition where the following vehicle can catch up with the preceding vehicle. Based on this critical consideration, this step only considers the process of two vehicles forming a convoy.

[0105] Once a vehicle is identified as the lead vehicle, it maintains its current constant speed, then accelerates to the maximum speed on the main line at the very end of the formation. When a vehicle is identified as a follower, it initially maintains a constant speed (this period is designed to prevent collisions when joining the preceding convoy), and once the required distance is met, it accelerates to the maximum speed on the main line, then continues at maximum speed until it joins the preceding convoy. Therefore, the convoy forms as vehicles leave the formation and enter the merging zone at the maximum speed on the main line.

[0106] In order to control the speed of a vehicle, it is necessary to calculate the time of motion at each stage. , , The corresponding expression is:

[0107]

[0108]

[0109]

[0110] Therefore, the movement time of each stage can be obtained through calculation, and the movement behavior of vehicles entering the formation area can be analyzed. Based on this, the active formation process of vehicles entering the area is clarified.

[0111] Trucks and passenger cars form convoys within the merging zone at different speeds and accelerations, and then exit the convoy zone. This means that all vehicles on the main line enter the merging zone in queues, and each individual vehicle is controlled as a separate convoy. (The diagram illustrates the convoy status for different vehicle types.) Figure 8 As shown, it is important to note that passenger cars and trucks will only form platoons and enter the merging area as a convoy if they meet the platooning requirements. Vehicles that do not meet the requirements will enter the merging area individually. Figure 8 This only indicates situations where vehicles enter the merging area in a convoy.

[0112] S3. Within the merging zone, based on the vehicle queue and the status information of vehicles approaching the ramps, and taking into account the heterogeneous characteristics of large trucks and passenger cars, an improved estimated arrival time calculation method is used to determine the merging sequence and merging speed of mainline vehicles and ramp vehicles.

[0113] In an optional embodiment of the present invention, within the merging zone, based on the status information of the vehicle queue and on-ramp vehicles, and taking into account the heterogeneous characteristics of large trucks and passenger cars, an improved estimated arrival time calculation method is used to determine the merging sequence and merging speed of mainline vehicles and on-ramp vehicles, including:

[0114] B1. Determine whether the vehicle type of the vehicle entering the merging area on the ramp is a smart connected truck; if yes, proceed to step B2; otherwise, proceed to step B3.

[0115] B2. Determine whether the vehicle type of the mainline vehicles is a single intelligent connected vehicle; if so, determine that the intelligent connected vehicles on the mainline have priority; otherwise, use the improved estimated arrival time calculation method to determine the merging sequence and merging speed of the mainline vehicles and the ramp vehicles.

[0116] B3. Determine whether the vehicle type of the mainline vehicles is a queue of intelligent connected trucks; if so, determine that the intelligent connected vehicles on the ramp have priority; otherwise, use the improved estimated arrival time calculation method to determine the merging sequence and merging speed of the mainline vehicles and the ramp vehicles.

[0117] The improved method for calculating estimated arrival times optimizes the merging sequence of mainline vehicle queues and ramp vehicles, including:

[0118] The maximum achievable speed of the vehicles on the ramp is calculated based on the vehicle information of the ramp vehicles.

[0119] The vehicle merging speed is determined by the smaller of the maximum achievable speed of ramp vehicles and the speed of mainline vehicles, and the estimated arrival time of vehicles is determined based on the vehicle merging speed.

[0120] Based on the estimated arrival time of vehicles, the passage priority of vehicles or convoys is determined to form a vehicle merging sequence.

[0121] The maximum achievable speed of vehicles on the ramp is calculated based on the vehicle information of the ramp vehicles, including:

[0122] Calculate the acceleration distance of the vehicles on the ramp based on their vehicle information;

[0123] Compare the length of the merging zone of the ramp with the acceleration distance of the vehicles on the ramp;

[0124] If the length of the merging zone is less than the acceleration distance of the vehicles on the merging zone, the maximum achievable speed of the vehicles on the merging zone is calculated based on their speed when they reach the starting point of the merging zone.

[0125] If the length of the merging zone of the ramp is greater than or equal to the acceleration distance of the ramp vehicles, then the speed limit on the main road shall be used as the maximum achievable speed of the ramp vehicles.

[0126] The vehicle merging speed is determined by the smaller of the maximum reachable speed of ramp vehicles and the speed of mainline vehicles, and the estimated arrival time of vehicles is determined based on the vehicle merging speed, including:

[0127] Compare the maximum achievable speed of vehicles on the ramp with the speed of vehicles on the main line;

[0128] If the maximum speed of vehicles on the ramp is greater than or equal to the speed of vehicles on the main road, then the speed of vehicles on the main road is used as the merging speed. The estimated arrival time of vehicles on the main road to the merging point is calculated based on the merging speed. Then, the estimated arrival time of the main road convoy is calculated based on the average of the estimated arrival times of each vehicle on the main road to the merging point. Finally, the estimated arrival time of vehicles on the ramp is calculated based on the merging speed.

[0129] If the maximum achievable speed of ramp vehicles is less than or equal to the speed of mainline vehicles, then the maximum achievable speed of ramp vehicles is used as the merging speed. The estimated arrival time of mainline vehicles at the merging point is calculated based on the speeds of mainline vehicles and ramp vehicles at the merging point. Then, the estimated arrival time of the mainline convoy is calculated based on the average of the estimated arrival times of all mainline vehicles in the convoy. Finally, the estimated arrival time of ramp vehicles is calculated based on the speeds of ramp vehicles at the merging point.

[0130] The vehicle sequence optimization method for merging zones considering the impact of queuing proposed in this embodiment aims to utilize the advanced technology of CAV (Carrier Aerial Vehicle) to perceive road and vehicle information in real time, fully leverage the advantages of vehicle queuing, and regulate the efficient merging of mainline vehicles and ramp vehicles. Specifically, this invention takes into account the acceleration and speed limits of the vehicle merging process, as well as the required safe merging distances for vehicles in the same and different lanes, during the entire merging sequence determination process. Under these constraints, the merging time and speed of each vehicle are determined, and then the vehicle speed trajectories are planned to achieve coordinated merging optimization of mainline vehicles and ramp vehicles.

[0131] In scenarios involving both types of vehicles, when mainline vehicles arrive at the merging area in platoons while ramp vehicles arrive individually, the problem of determining the merging sequence expands from mainline vehicles merging with ramp vehicles, and mainline platoons merging with ramp vehicles, to merging problems involving mainline passenger cars, mainline passenger car platoons, mainline trucks, and mainline truck platoons merging with ramp passenger cars and ramp trucks. This embodiment addresses the merging problems of truck platoons and trucks in scenarios with different vehicle types, ultimately simplifying it to the problem of determining the merging sequence of mainline truck platoons, trucks, ramp trucks, and passenger car platoons and ramp trucks, i.e., determining the passage priority of passenger cars, passenger car platoons, trucks, and truck platoons within the merging area.

[0132] Considering the performance differences between trucks and passenger cars, and the greater fuel consumption resulting from truck acceleration and deceleration, when a passenger car on the main line encounters a truck on the ramp, the passenger car on the main line has priority. When a convoy of trucks on the main line encounters a passenger car on the ramp, the passenger car on the ramp has priority. In all other cases, a vehicle sequence optimization method considering queuing effects is used to determine priority. The specific adjustment rules are as follows: Figure 9 As shown.

[0133] When mainline vehicles merge in platoons, if the merging order is determined using a first-in, first-out (FIFO) rule, and the mainline platoon is long and arrives before the ramp vehicles, the ramp vehicles need to wait, reducing the merging efficiency of the ramp vehicles and resulting in a loss of total merging time. Therefore, this invention proposes an improved method for estimating arrival time to determine the merging sequence of mainline platoons and ramp vehicles. The estimated arrival time of the platoon is not simply replaced by the arrival time of the lead vehicle, but rather by comprehensively considering the arrival times of all vehicles in the platoon, taking their average, and then determining the merging sequence. Based on the specified arrival times, the speed trajectory is determined, allowing the mainline platoon and ramp vehicles to merge in an orderly manner. In addition, this method also considers the speed difference between mainline and ramp vehicles, as well as different scenarios where ramp vehicles can accelerate to the merging speed. Since there are fewer ramp vehicles, waiting for vehicles to form a queue would cause significant time loss; therefore, this invention only considers platooning of mainline vehicles.

[0134] The method for determining the merging order consists of three steps: calculating the maximum achievable speed of the ramp, determining the estimated arrival time of vehicles, and allocating the vehicle merging sequence. The process is as follows:

[0135] Step 1: Calculate the maximum achievable speed of vehicles on the ramp.

[0136] Vehicles merging from the ramp onto the main road need to accelerate. Assuming the vehicle accelerates at its maximum speed, the corresponding acceleration time and distance can be calculated.

[0137]

[0138]

[0139] The acceleration distance is compared to the length of the control zone in two scenarios. The first scenario is that the length of the control zone is insufficient for the vehicle to accelerate to the speed limit on the main road. Therefore, the following equation can be derived:

[0140]

[0141]

[0142] Find:

[0143]

[0144]

[0145] The second scenario is that vehicles on the ramp are able to accelerate to the speed limit on the main road before merging into it. In this case, the maximum speed that vehicles can reach on the ramp is the speed limit on the main road:

[0146]

[0147] In the above formula, The length of the merging zone of the main road, The length of the merging zone of the ramp. This refers to the speed limit value for the main road of the highway. The speed of vehicles on the main road when they arrive at the starting point of the merging zone. The speed of vehicles arriving at the starting point of the merging zone from the ramp. This is the vehicle's maximum acceleration. For vehicles on the ramp from Accelerate to The minimum time used For vehicles on the ramp from Accelerate to The distance traveled This represents the maximum achievable speed for vehicles arriving at the merging point from the entrance ramp. This is the minimum reachable time for a vehicle to travel on the entrance ramp. Estimated time for vehicles on the main road to reach the merging point. Estimated time for the main road convoy to reach the merging point. For the team number, This is the estimated time for vehicles on the ramp to arrive at the merging point. This is the estimated merging speed at the merging point.

[0148] Step 2: Determine the estimated arrival time of the vehicle.

[0149] The maximum achievable speed of vehicles on the ramp has been calculated. Vehicles on the main road travel at their maximum speed when leaving the platooning zone. By comparing the maximum achievable speed of vehicles on the ramp with the speed of vehicles on the main road, the lower of the two values ​​is set as the vehicle merging speed. Therefore, two situations may occur. In the first situation, the speed of the main line convoy is less than the maximum speed that the ramp vehicles can reach, and the merging speed is set to the speed of the main line convoy. In the second situation, the speed of the main line convoy is greater than the maximum speed that the ramp vehicles can reach, and the merging speed is set to the maximum speed that the ramp vehicles can reach.

[0150] (1) When hour,

[0151] The estimated arrival time of the convoy on the main road is obtained by averaging the arrival times of all vehicles in the convoy:

[0152]

[0153]

[0154] in, Let be the number of vehicles in the queue. At this point, vehicles on the ramp can accelerate to the merging speed before merging, which can be expressed by the following equation:

[0155]

[0156]

[0157] The estimated arrival time of vehicles on the ramp is as follows:

[0158]

[0159] (2) When hour,

[0160] In this situation, the speed of the mainline convoy is greater than the merging speed, and it needs to decelerate before reaching the merging point. Using the area formula, the estimated arrival time of the mainline convoy can be calculated as follows:

[0161]

[0162]

[0163] In this situation, vehicles on the ramp cannot accelerate to the speed of the mainline convoy, and the estimated arrival time for the ramp vehicles is:

[0164] .

[0165] S4. Based on the type of vehicles entering the merging zone, an improved estimated arrival time calculation method is used to optimize the merging sequence of the mainline vehicle queue and the ramp vehicle queue, and energy-saving optimization is performed on the vehicle acceleration curve during the merging process.

[0166] In an optional embodiment of the present invention, energy-saving optimization of the vehicle acceleration curve during the merging process includes:

[0167] A collaborative control model for ramp merging under heterogeneous traffic flow conditions is constructed based on the state equation, velocity and acceleration constraints, safety clearance constraints, initial and termination conditions, and the objective function; where the safety clearance constraint is:

[0168]

[0169]

[0170]

[0171] in, Let j be the distance from the intelligent connected vehicle j to the merging point at time t. Let K be the distance from the merging point to the intelligent connected truck at time t. This refers to the minimum permissible headway between intelligent connected vehicles. The minimum permissible headway between intelligent connected trucks (k-type). This refers to the minimum permissible headway between intelligent connected vehicles and intelligent connected trucks.

[0172] The collaborative control model for ramp merging under heterogeneous traffic flow environment is solved to obtain the speed of all vehicles from the initial moment of entering the merging zone to the merging time of reaching the merging point.

[0173] When a vehicle arrives at the merging control zone, the central processing unit immediately calculates the merging sequence and performs trajectory planning. After determining the merging sequence, the vehicle speed trajectory needs to be planned. Speed ​​trajectory planning aims to ensure that vehicles arrive safely at the merging area within a predetermined time while meeting vehicle and road restrictions, and to maintain an appropriate safe following distance during the planning process. This embodiment considers the differences in the operating characteristics of large trucks and establishes a ramp merging cooperative control model under heterogeneous traffic flow environment. The ramp merging cooperative control model consists of five parts: state equations, velocity and acceleration constraints, safety constraints, initial and termination conditions, and objective function, thus obtaining the optimal model for ramp merging.

[0174] In real-world scenarios, the real-time state of a vehicle is complex. In this model, the vehicle's motion is defined as a point mass moving along the center of the lane. It is assumed that each vehicle has the same dynamic characteristics. The dynamic relationship is as follows:

[0175]

[0176]

[0177] in, , Indicates the initial time. Indicates the final time when merging vehicles arrive at the merging point. Indicates at time vehicle Distance to the merging point (negative before the merging point, positive after the merging point). and They are vehicles In time The velocity and acceleration.

[0178] First, regardless of whether it's a passenger car or a large truck, the speed and acceleration of all vehicles must meet the boundary constraints:

[0179]

[0180]

[0181] It is worth noting that the maximum acceleration and deceleration of trucks differs from that of passenger cars. Secondly, for all passenger cars... All large trucks During the merging process, relevant state constraints need to be satisfied. The formula for the safety clearance is as follows:

[0182]

[0183]

[0184]

[0185] in, This indicates the minimum permissible headway between passenger cars. This indicates the minimum permissible headway between trucks. This indicates the minimum permissible headway between passenger cars and trucks. The merging time of the vehicles must also meet relevant safety constraints.

[0186]

[0187] in, Indicates the time when merging vehicles arrive at the merging point. This represents the safe merging gap. Since the time and speed at which the vehicle finally passes through the merging point are already determined, the vehicle's final state during the merging process can be used as a constraint input.

[0188]

[0189]

[0190]

[0191] in, Indicates that the vehicle is in Distance from the merging point at any given time. The length of the merging zone, Let be the merging velocity. Therefore, when a vehicle arrives at the merging zone, considering the length and acceleration / deceleration capabilities of each vehicle, the vehicle's state can be defined as:

[0192]

[0193] Under the constraint of vehicle merging Next, considering multiple performance metrics, an objective function is constructed. The objective function is:

[0194]

[0195] Considering the impact of vehicle acceleration, the higher the acceleration, the longer the acceleration duration, the lower the merging efficiency, and the worse the fuel economy and vehicle comfort. Therefore, minimizing the acceleration during vehicle operation can effectively reduce fuel consumption and improve efficiency.

[0196] Based on the above constraints and objective function, the optimization problem for coordinated control of ramp merging, considering the impact of queues and large trucks, is as follows:

[0197]

[0198]

[0199] By solving the above problems, we can obtain the results from... arrive The specific speed values ​​of all vehicles at each simulation step within a given time period are calculated. Each vehicle travels to the merging point at the calculated speed, enabling efficient merging. After determining the vehicle merging sequence and the target speed to the merging point, speed-saving planning based on smooth acceleration curves is performed on the vehicle merging process. In this invention, the Gurobi solver is used to solve the cooperative control optimization problem.

Claims

1. A method for optimizing intelligent connected vehicle merging on highway ramps, considering the impact of large trucks, characterized in that, Includes the following steps: The area upstream of the merging point is divided into the mainline vehicle adjustment area and the merging area. The mainline vehicle adjustment area is further subdivided into the lane-changing area and the formation area, and the lengths of the mainline vehicle lane-changing area and the formation area are determined. Coordinated control of mainline vehicles within the mainline vehicle adjustment zone; The coordinated control includes: guiding some mainline vehicles to change lanes and divert in the lane-changing area based on safety gaps and speed constraints, creating merging space for ramp vehicles; and controlling the vehicles in the remaining outer lanes to form a vehicle queue in the formation area. Within the merging zone, based on the vehicle queue and ramp arrival status information, and taking into account the heterogeneous characteristics of large trucks and passenger cars, an improved estimated arrival time calculation method is used to determine the merging sequence and merging speed of mainline vehicles and ramp vehicles, including: B1. Determine whether the vehicle type of the vehicle entering the merging area on the ramp is a smart connected truck; if yes, proceed to step B2; otherwise, proceed to step B3. B2. Determine whether the vehicle type of the mainline vehicles is a single intelligent connected vehicle; if so, determine that the intelligent connected vehicles on the mainline have priority; otherwise, use the improved estimated arrival time calculation method to determine the merging sequence and merging speed of the mainline vehicles and the ramp vehicles. B3. Determine whether the vehicle type of the mainline vehicles is a queue of intelligent connected trucks; if so, determine that the intelligent connected vehicles on the ramp have priority; otherwise, use the improved estimated arrival time calculation method to determine the merging sequence and merging speed of the mainline vehicles and the ramp vehicles. The improved estimated arrival time calculation method is used to determine the merging sequence and merging speed of mainline vehicles and ramp vehicles, including: The maximum achievable speed of the vehicles on the ramp is calculated based on the vehicle information of the ramp vehicles. The vehicle merging speed is determined by the smaller of the maximum achievable speed of ramp vehicles and the speed of mainline vehicles, and the estimated arrival time of vehicles is determined based on the vehicle merging speed. The estimated arrival time of vehicles determines the passage priority of vehicles or convoys, forming a vehicle merging sequence; The vehicle merging speed is determined by the smaller of the maximum reachable speed of ramp vehicles and the speed of mainline vehicles, and the estimated arrival time of vehicles is determined based on the vehicle merging speed, including: Compare the maximum achievable speed of vehicles on the ramp with the speed of vehicles on the main line; If the maximum speed of vehicles on the ramp is greater than or equal to the speed of vehicles on the main road, then the speed of vehicles on the main road is used as the merging speed. The estimated arrival time of vehicles on the main road to the merging point is calculated based on the merging speed. Then, the estimated arrival time of the main road convoy is calculated based on the average of the estimated arrival times of each vehicle on the main road to the merging point. Finally, the estimated arrival time of vehicles on the ramp is calculated based on the merging speed. If the maximum achievable speed of ramp vehicles is less than or equal to the speed of mainline vehicles, the maximum achievable speed of ramp vehicles is used as the merging speed. The estimated arrival time of mainline vehicles at the merging point is calculated based on the speeds of mainline vehicles and ramp vehicles at the merging point. The estimated arrival time of the mainline convoy is then calculated based on the average of the estimated arrival times of all mainline vehicles in the convoy. Finally, the estimated arrival time of ramp vehicles is calculated based on their speeds at the merging point. Based on the determined merging sequence and merging velocity, energy-saving optimization is performed on the acceleration curves of each vehicle within the merging zone.

2. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 1, is characterized in that... In the lane-changing area, based on safety clearances and speed constraints, some mainline vehicles are guided to change lanes and divert traffic, including: The headway between the current vehicle and the vehicles in front and behind in adjacent lanes is determined based on the vehicle information and movement status of intelligent connected vehicles and intelligent connected trucks. The absolute safe following distance for intelligent connected vehicles and the safe lane-changing distance for intelligent connected trucks are determined based on the vehicle information and movement status of intelligent connected vehicles and intelligent connected trucks, respectively. The absolute safe headway for a vehicle to change lanes is determined by the larger of the absolute safe following distance and the safe lane-changing distance. Determine whether the headway between the current vehicle and the vehicles in front and behind in the adjacent lane is greater than the absolute safe headway for the vehicle to change lanes; if so, proceed to the next step; otherwise, do not control the current vehicle to change lanes. Determine if the current vehicle's speed meets the speed range of the vehicles in front and behind in the target lane; if so, control the current vehicle to change lanes; otherwise, do not control the current vehicle to change lanes.

3. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 2, is characterized in that... The absolute safe following distance of an intelligent connected vehicle is determined based on its vehicle information and movement status, specifically as follows: ； Where S represents the absolute safe following distance. It is the sum of the reaction distance and braking distance of the following vehicle. For safe parking distance, This is the braking distance of the vehicle in front. The speed of the car in front. For the speed of the following vehicle, For driver reaction time, For the reaction time of braking operation of intelligent connected vehicles, This is the vehicle's maximum acceleration.

4. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 2, is characterized in that... The safe lane-changing distance for intelligent connected trucks is determined based on their vehicle information and movement status, specifically as follows: ； Where D represents the lane-changing safety distance. For the speed of intelligent connected trucks, The reaction time for braking operations of intelligent connected trucks. It is the acceleration due to gravity. The coefficient of friction of the road. The slope of the road. This refers to the vehicle's length.

5. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 1, is characterized in that... In the formation area, control the vehicles in the remaining outer lanes to form a vehicle queue, including: A1. Determine if the current vehicle entering the formation area is the same model as the vehicle in front; if so, proceed to step A2; otherwise, form the current vehicle into the formation according to the speed control of the lead vehicle. A2. Calculate the current distance and critical distance between the current vehicle and the vehicle in front; A3. Determine if the current distance between the current vehicle and the vehicle in front is greater than the critical distance; if so, assemble the current vehicles according to the speed control of the lead vehicle; otherwise, proceed to step A4. A4. Determine if the convoy size of the preceding vehicle has reached the maximum convoy size; if so, then convoy the current vehicle according to the speed control of the lead vehicle; otherwise, convoy the current vehicle according to the speed control of the following vehicles.

6. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 1, is characterized in that... The maximum achievable speed of vehicles on the ramp is calculated based on the vehicle information of the ramp vehicles, including: Calculate the acceleration distance of the vehicles on the ramp based on their vehicle information; Compare the length of the merging zone of the ramp with the acceleration distance of the vehicles on the ramp; If the length of the merging zone is less than the acceleration distance of the vehicles on the merging zone, the maximum achievable speed of the vehicles on the merging zone is calculated based on their speed when they reach the starting point of the merging zone. If the length of the merging zone of the ramp is greater than or equal to the acceleration distance of the ramp vehicles, then the speed limit on the main road shall be used as the maximum achievable speed of the ramp vehicles.

7. The intelligent connected vehicle merging optimization method for highway ramps considering the impact of large trucks, as described in claim 1, is characterized in that... Based on the determined merging sequence and merging velocity, energy-saving optimization is performed on the acceleration curves of each vehicle within the merging zone, including: A collaborative control model for ramp merging under heterogeneous traffic flow conditions is constructed based on the state equation, velocity and acceleration constraints, safety clearance constraints, initial and termination conditions, and the objective function; where the safety clearance constraint is: ； ； ； in, Let j be the distance from the intelligent connected vehicle j to the merging point at time t. Let K be the distance from the merging point to the intelligent connected truck at time t. This refers to the minimum permissible headway between intelligent connected vehicles. The minimum permissible headway between intelligent connected trucks (k-type). This refers to the minimum permissible headway between intelligent connected vehicles and intelligent connected trucks. The collaborative control model for ramp merging under heterogeneous traffic flow environment is solved to obtain the speed of all vehicles from the initial moment of entering the merging zone to the merging time of reaching the merging point; After determining the vehicle merging sequence and the target speed at the merging point, speed-saving planning based on smooth acceleration curves is performed on the vehicle merging process.

Images