Unified straight road section traffic conflict identification method without distinguishing traffic conflict types

Abstract

According to the unified identification method for the straight road section traffic conflicts, the types of the traffic conflicts do not need to be distinguished in advance, strict requirements for the driving direction, the number of lanes, the number of motor vehicles and the types do not exist, a unified identification model for the traffic conflicts is constructed, and the potential collision time TU is calculated; on the basis of vehicle states at all moments in the conflict process, complete risk measurement within the conflict duration is identified, the risk degree of collision between the vehicles can be rapidly and accurately estimated, the traffic conflict judgment speed and accuracy are greatly improved, and a new direction for identifying the traffic conflict without judging the conflict type in advance is created.

Description

Technical Field

[0001] The present application relates to the technical field of traffic safety risk identification, and in particular to a unified identification method for traffic conflicts on straight road sections that do not distinguish between traffic conflict types. Background Art

[0002] Commonly used traffic conflict identification methods in TCT (Traffic conflict technology) include TTC (Time to Collision), PET (Post Encroachment Time), DRAC (Deceleration rate to avoid crash), etc. These methods have good identification effects within their respective scopes of application, but the identification effects of traffic conflicts outside the scope of application need to be improved. With the expansion of the application scope of TCT, the scenarios it faces have gradually shifted from single scenarios to complex scenarios such as merging areas and interweaving areas. In complex scenarios, there are frequent conflicts such as following vehicles, changing lanes, and merging. For conflict identification where multiple types of conflicts coexist, the existing conflict identification methods need to be expanded and their adaptability needs to be enhanced.

[0003] The current single method and combined method identification have certain defects: (1) There are different defects in the identification of multiple types of traffic conflicts in specific scenarios using a single method. Methods such as PET, TTC, and DRAC are better at identifying conflicts with following vehicles based on the time difference in passing through public areas, the time from the potential collision point, and the vehicle's own motion characteristics. However, they are not very accurate in identifying lane change conflicts, especially DRAC, which is limited by its definition and is almost only used for the identification of conflicts with following vehicles. The reason is that the collision conditions in the lane change state are more complex, and the accurate potential collision point is difficult to estimate; (2) In order to identify multiple types of conflicts in complex scenarios, some scholars have used the advantages of a single method in identifying different types of conflicts, and adopted a combination of multiple single methods to measure the risk level between vehicles for multiple types of conflicts. Directly use multiple single methods to identify traffic conflicts, and comprehensively measure risks based on the identification results of multiple single methods, such as using TTC to identify following conflicts and TDTC (Time Difference to Collision) to identify lane change conflicts. The combined method can retain the advantages of a single method, so it improves the effect of identifying multiple types of conflicts. However, there is no unified and clear distinction between following conflicts and lane change conflicts, and this superimposed combination method still needs to first identify the conflict type and adopt different methods for vehicles of different conflict types, resulting in inaccurate results.

[0004] The common superposition combination method only weakens or even retains the defects of a single method. Under the influence of the difficulty in distinguishing the conflict type, the complexity of conflict identification increases, making it difficult to apply universally. To achieve multi-type conflict identification in complex scenarios, it is still necessary to propose a unified identification method based on different traffic conflict types. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a unified identification method for traffic conflicts on straight road sections that does not distinguish between traffic conflict types in response to the above-mentioned problems. By constructing a unified traffic conflict identification model, traffic conflicts can be directly identified without pre-determining the conflict type.

[0006] The embodiment of the present application is implemented as follows: The present application provides a unified identification method for traffic conflicts on a straight road section that does not distinguish between traffic conflict types, characterized by comprising the following steps: Step a, determine the collision conditions between the front vehicle A and the rear vehicle B: The following, lane changing and crossing movements of vehicles on the road are described as the planar movement of the vehicles in a two-dimensional coordinate system. The conflicting vehicles are further projected onto the x-axis and y-axis of the coordinate system respectively. When there is no potential collision between the conflicting vehicles, at least one of the projections on the x-axis and y-axis does not overlap. When there is a potential collision between the conflicting vehicles, the projections on both the x-axis and y-axis overlap. That is, the condition for the potential collision between the conflicting vehicles is described as the simultaneous overlap of the projections of the two vehicles on the x-axis and y-axis. Step b, identifying the collision risk between the front vehicle A and the rear vehicle B: Step b1, projection of the front vehicle A and the rear vehicle B onto the x and y axes: The current positions of the vehicles are and The current speeds of the vehicles are , the decomposed velocity in the x-axis and y-axis directions is , the projection boundary points of vehicle A on the x-axis and y-axis can be obtained by projecting the vehicle. ,make , The four boundary points are respectively called the front and rear of the projection of car A on the x-axis, and the front and rear of the projection on the y-axis; similarly, the projection boundary points of car B on the x-axis and y-axis are ,make , , the four boundary points are respectively called the front and rear of car B projected on the x-axis, and the front and rear of car B projected on the y-axis; Step b2, vehicle projection overlap parameters are determined: is the minimum displacement that the vehicle projection in the x-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the x-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the x-axis direction , the time required; is the minimum displacement that the vehicle projection in the y-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the y-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the y-axis direction , The time required; the above eight parameters are used to identify the vehicle projection overlap parameters; Step c: determine whether the projections of the vehicle on the x and y axes overlap at the same time: based on The definition of , the time period when the projections of the two vehicles overlap in the x-axis direction is , the time period when the projections of the two vehicles overlap on the y-axis direction is The condition for a potential collision between the conflicting vehicles is that the projections of the two vehicles on the x-axis and y-axis overlap at the same time, that is, the lower limit of the two time periods and None , and the two time periods and The intersection of is not an empty set; the intersection corresponds to the duration of a potential collision between two vehicles in theory. The potential collision time is the time required for a collision to occur. TU is the lower limit of the intersection, and the conflict identification formula is as follows; .

[0007] In some optional embodiments, step b2 The calculation process is as follows: When the projections of the two vehicles overlap on the x-axis is 0; when the projections of the two vehicles do not overlap in the x-axis direction, is the distance from the front of the rear vehicle to the rear of the front vehicle in the x-axis direction, calculated using the projection boundary points , as follows:

[0008] In the formula, is the distance from the front of vehicle A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the rear of car A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the front of vehicle B projected on the x-axis to the origin of the coordinate axis O, in meters; It is the distance from the rear of car B projected on the x-axis to the origin O of the coordinate axis, in meters.

[0009] In some optional embodiments, the step b2 The calculation process is as follows: According to The size of the vehicle coordinates and the relationship between the vehicle speed. It is divided into four cases, as shown in the following formula: .

[0010] In some optional embodiments, the step b2 The calculation process is as follows: it is affected by the positions of the two vehicles, whether the projections overlap at the current moment, and the speed of the front and rear vehicles. It is divided into six cases, as shown below: .

[0011] In some optional embodiments, the step b2 The calculation process is as follows: The situation when there are non-infinite solutions is The six cases involved are the same, as shown in the following formula: .

[0012] In some optional embodiments, the step b2 The calculation formula is as follows: .

[0013] In some optional embodiments, the step b2 The calculation formula is as follows: .

[0014] In some optional embodiments, the step b2 The calculation formula is as follows: .

[0015] In some optional embodiments, the step b2 The calculation formula is as follows: .

[0016] In some optional embodiments, the lower limit of the intersection in step c must also be the lower limit of the two time periods. and One, based on the vehicle status at each moment during the conflict process, TU Identify the complete risk metric over the duration of the conflict as shown below: .

[0017] The beneficial effects of the present application are as follows: the present application provides a unified identification method for traffic conflicts on straight sections that does not distinguish between traffic conflict types, which can better identify traffic conflicts, and the identification results are less affected by the pre-identification of the conflict type, thereby being able to more accurately describe the risk level between vehicles and provide more appropriate guidance on the conflict type and risk avoidance behavior; at the same time, during the identification process, the unified identification method does not require pre-identification of the conflict type, which reduces the complexity of multi-type conflict identification, makes risk identification simpler, and makes risk assessment faster; the present invention can improve the speed and accuracy of risk assessment of autonomous driving vehicles, thereby facilitating faster and more accurate decision-making in the trajectory and motion planning of autonomous driving vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the projection of the vehicle onto the x-axis and the y-axis when no potential collision occurs in an embodiment of the present application; Figure 2 It is a schematic diagram of the projection of the vehicle onto the x-axis and the y-axis when a potential collision occurs in an embodiment of the present application; Figure 3 A schematic diagram of the coordinates and distances of projection boundary points in an embodiment of the present application; Figure 4 For the embodiments of this application Schematic diagram of the separation of future projections when the current vehicle projections overlap; Figure 5 For the embodiments of this application Schematic diagram of the separation of future projections when the current vehicle projections overlap. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0024] The present invention proposes a unified identification method for traffic conflicts on straight sections that does not distinguish between traffic conflict types. The method is applicable to the identification of traffic conflicts on straight sections, has no strict requirements on the types of traffic conflicts, driving directions, number of lanes, number and type of motor vehicles, and has strong universality. For example, a straight basic section has several lanes and several motor vehicles, and there are following and lane-changing conflicts between vehicles. The above invention content can be used to quickly and accurately estimate the risk of collision between vehicles, greatly improving the speed and accuracy of traffic conflict identification, creating a new direction for identifying traffic conflicts without pre-identifying the conflict type, and has extremely high scientific and application value.

[0025] The specific steps include: Step 1: Convert vehicle trajectory from two-dimensional to one-dimensional This method describes the movement of vehicles on the road, such as following, changing lanes, and crossing, as the planar movement of the vehicles in a two-dimensional coordinate system. The conflicting vehicles are further projected onto the x-axis and y-axis of the coordinate system. For example, A is the front vehicle and B is the rear vehicle. The specific conditions for identifying the occurrence of a collision are: when the conflicting vehicles do not have a potential collision, at least one of the projections on the x-axis and y-axis does not overlap, such as Figure 1 When the conflicting vehicles have a potential collision, the projections in both one-dimensional directions overlap, as shown in Figure 2 As shown in Figure 2, the condition for a potential collision between conflicting vehicles is described as the simultaneous overlap of the projections of the two vehicles in the two one-dimensional directions of the x-axis and the y-axis.

[0026] Step 2: Identify the risk of collision between vehicles A and B 2.1 Projection of vehicles A and B onto the x and y axes The current positions of the vehicles are and The current speeds of the vehicles are , the decomposed velocity in the x-axis and y-axis directions is , the projection boundary points of vehicle A on the x-axis and y-axis can be obtained by projecting the vehicle. ,make , The four boundary points are respectively called the front and rear of the projection of car A on the x-axis, and the front and rear of the projection on the y-axis; similarly, the projection boundary points of car B on the x-axis and y-axis are ,make , The four boundary points are called the front and rear of car B projected on the x-axis, and the front and rear of car B projected on the y-axis.

[0027] 2.2 Calculation of vehicle projection overlap parameters is the minimum displacement that the vehicle projection in the x-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the x-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the x-axis direction , the time required; is the minimum displacement that the vehicle projection in the y-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the y-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the y-axis direction , The time required; the above eight parameters are the vehicle projection overlap parameters (see Figure 3 ).

[0028] 2.2.1 Calculation

[0029] When the projections of the two vehicles overlap on the x-axis is 0; when the projections of the two vehicles do not overlap in the x-axis direction, is the distance from the front of the rear vehicle to the rear of the front vehicle in the x-axis direction, calculated using the projection boundary points , as follows:

[0030] In the formula, is the distance from the front of vehicle A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the rear of car A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the front of vehicle B projected on the x-axis to the origin of the coordinate axis O, in meters; It is the distance from the rear of car B projected on the x-axis to the origin O of the coordinate axis, in meters.

[0031] 2.2.2 Calculation

[0032] according to The size of the vehicle coordinates and the relationship between the vehicle speed. It is divided into four cases, as shown in the following formula: .

[0033] 2.2.3 Calculation

[0034] When the projections of the two vehicles overlap on the x-axis, There are two situations. One is that the speed of the rear car is greater than that of the front car, and the rear car will pass the front car. The distance from the rear of the following vehicle to the front of the preceding vehicle (see Figure 4 ); second, if the speed of the rear car is lower than that of the front car, the rear car will fall further behind the front car. The minimum distance required for the rear vehicle to completely lag behind the front vehicle, that is, the distance from the front of the rear vehicle to the rear of the front vehicle (see Figure 5 ). At the current moment, the projections of the two vehicles on the x-axis do not overlap. is the distance from the front of the rear car to the rear of the front car. It can be divided into six cases depending on the positions of the two cars, whether the projections overlap at the current moment, and the speeds of the front and rear cars, as shown in the following formula: .

[0035] 2.2.4 Calculation

[0036] is the minimum time required for the vehicle projections to separate again after overlapping in the x-axis direction. When there is a non-infinite solution, it includes the following situations: The six cases involved are the same, as shown in the following formula: .

[0037] 2.2.5 Calculation

[0038] The calculation formula is as follows: .

[0039] 2.2.6 Calculation

[0040] The calculation formula is as follows: .

[0041] 2.2.7 Calculation

[0042] The calculation formula is as follows: .

[0043] 2.2.8 Calculation

[0044] The calculation formula is as follows: .

[0045] Step 3: Determine whether the vehicle's projections on the x and y axes overlap at the same time based on The definition of , the time period when the projections of the two vehicles overlap in the x-axis direction is , the time period when the projections of the two vehicles overlap on the y-axis direction is The condition for a potential collision between the conflicting vehicles is that the projections of the two vehicles on the x-axis and y-axis overlap at the same time, that is, the lower limit of the two time periods and None , and the two time periods and The intersection of is not an empty set; the intersection corresponds to the duration of a potential collision between two vehicles in theory. The potential collision time is the time required for a collision to occur. TU is the lower limit of the intersection, and the conflict identification formula is as follows; .

[0046] Obviously, the lower limit of the intersection must also be one of the lower limits of the two time periods, so the above formula can be rewritten as follows:

[0047] Based on the vehicle states at each moment during the conflict process, TU identifies the complete risk metric for the duration of the conflict.

Claims

1. A unified identification method for traffic conflicts on straight sections without distinguishing the types of traffic conflicts, characterized in that: The steps include: Step a, determine the collision conditions between the front vehicle A and the rear vehicle B: The following, lane changing and crossing movements of vehicles on the road are described as the planar movement of the vehicles in a two-dimensional coordinate system. The conflicting vehicles are further projected onto the x-axis and y-axis of the coordinate system respectively. When there is no potential collision between the conflicting vehicles, at least one of the projections on the x-axis and y-axis does not overlap. When there is a potential collision between the conflicting vehicles, the projections on both the x-axis and y-axis overlap. That is, the condition for the potential collision between the conflicting vehicles is described as the simultaneous overlap of the projections of the two vehicles on the x-axis and y-axis. Step b, identifying the collision risk between the front vehicle A and the rear vehicle B: Step b1, projection of the front vehicle A and the rear vehicle B onto the x and y axes: The current positions of the vehicles are and The current speeds of the vehicles are , the decomposed velocity in the x-axis and y-axis directions is , the projection boundary points of vehicle A on the x-axis and y-axis can be obtained by projecting the vehicle. ,make , The four boundary points are respectively called the front and rear of the projection of car A on the x-axis, and the front and rear of the projection on the y-axis; similarly, the projection boundary points of car B on the x-axis and y-axis are ,make , , the four boundary points are respectively called the front and rear of car B projected on the x-axis, and the front and rear of car B projected on the y-axis; Step b2, vehicle projection overlap parameters are determined: is the minimum displacement that the vehicle projection in the x-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the x-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the x-axis direction , the time required; is the minimum displacement that the vehicle projection in the y-axis direction needs to overcome from the judgment moment to the start of overlap, The minimum displacement in the y-axis direction that needs to be overcome from the beginning of the overlap of the vehicle projections until the moment when the projections separate again after overlapping; The distance between vehicles is reduced in the y-axis direction , The time required; the above eight parameters are used to identify the vehicle projection overlap parameters; Step c: determine whether the projections of the vehicle on the x and y axes overlap at the same time: based on The definition of , the time period when the projections of the two vehicles overlap in the x-axis direction is , the time period when the projections of the two vehicles overlap on the y-axis direction is The condition for a potential collision between the conflicting vehicles is that the projections of the two vehicles on the x-axis and y-axis overlap at the same time, that is, the lower limit of the two time periods and None , and the two time periods and The intersection of is not an empty set; The intersection corresponds to the duration of a potential collision between two vehicles in theory. The potential collision time is the time required for a collision to occur. TU is the lower limit of the intersection, and the conflict identification formula is as follows; 。 2. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 1, characterized in that: Step b2 The calculation process is as follows: When the projections of the two vehicles overlap on the x-axis is 0; when the projections of the two vehicles do not overlap in the x-axis direction, is the distance from the front of the rear vehicle to the rear of the front vehicle in the x-axis direction, calculated using the projection boundary points , as follows:

3. In the formula, is the distance from the front of vehicle A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the rear of car A projected on the x-axis to the origin of the coordinate axis O, in meters; is the distance from the front of vehicle B projected on the x-axis to the origin of the coordinate axis O, in meters; For car B The distance from the rear of the vehicle projected on the x-axis to the origin O of the coordinate axis, in meters.

4. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 1 or 2, characterized in that: As described in step b2 The calculation process is as follows: According to The size of the vehicle coordinates and the relationship between the vehicle speed. It is divided into four cases, as shown in the following formula: 。 5. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 3, characterized in that: As described in step b2 The calculation process is as follows: According to the positions of the two vehicles, the overlap of the projections at the current moment, and the speeds of the two vehicles, It is divided into six cases, as shown below: 。 6. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 4, characterized in that: As described in step b2 The calculation process is as follows: The situation when there are non-infinite solutions is The six cases involved are the same, as shown in the following formula: 。 7. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 5, characterized in that: As described in step b2 The calculation formula is as follows: 。 8. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 5, characterized in that: As described in step b2 The calculation formula is as follows: 。 9. The unified identification method for straight road section traffic conflicts without distinguishing traffic conflict types according to claim 5, characterized in that: As described in step b2 The calculation formula is as follows: 。 10. The unified identification method for straight road section traffic conflict without distinguishing traffic conflict types according to claim 5, characterized in that: As described in step b2 The calculation formula is as follows: 。 11. The unified identification method for straight road section traffic conflict without distinguishing traffic conflict types according to claim 5, characterized in that: The lower limit of the intersection in step c must also be the lower limit of the two time periods and One, based on the vehicle status at each moment during the conflict process, TU Identify the complete risk metric over the duration of the conflict as shown below: 。

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