Multi-uav offline route conflict detection and resolution method and device

Abstract

The application discloses a kind of multi-unmanned aerial vehicle offline route conflict detection and resolution method and device, wherein the method comprises: determining the flight segment of each unmanned aerial vehicle excessively close to other unmanned aerial vehicles based on safety distance constraint;Based on mixed integer linear programming model, the resolution constraints of existing conflict and potential conflict are coordinated, and the conflict resolution strategy of each unmanned aerial vehicle based on departure time adjustment is determined.The application provides a kind of multi-unmanned aerial vehicle offline route conflict detection and resolution scheme based on time variable description, can take into account the safety interval and air traffic efficiency of unmanned aerial vehicle flying in crowded environment.The application can be widely applied to the field of unmanned aerial vehicle cooperative control technology.

Description

Technical Field

[0001] This invention relates to the field of collaborative control technology for unmanned aerial vehicles (UAVs), and in particular to a method and apparatus for detecting and resolving offline flight path conflicts among multiple UAVs. Background Technology

[0002] Based on the non-contact operation characteristics of drones, people can flexibly use them to complete tasks such as transportation, inspection, and patrol in daily life. With the development of drone technology, the promotion and application of drones has received increasing attention, with the expectation of exploring their potential in urban low-altitude airspace to enable them to perform more tasks and facilitate people's daily lives. One of the key issues that must be addressed to enable wider application of drones in urban low-altitude airspace is the detection and resolution of airspace conflicts during drone operation, ensuring the orderly and safe operation of a large number of drones within a limited airspace. Currently, there are few methods for offline flight path conflict detection and resolution for drones. To ensure the operational safety of drones, existing methods mainly employ spatiotemporal separation and partitioning, but these methods limit the number of drones operating in the airspace and are relatively inefficient. Summary of the Invention

[0003] In order to at least partially solve one of the technical problems existing in the prior art, the purpose of this invention is to provide a method and apparatus for detecting and resolving offline flight path conflicts of multiple UAVs based on time variable description.

[0004] The technical solution adopted in this invention is:

[0005] A method for detecting and resolving offline flight path conflicts among multiple unmanned aerial vehicles (UAVs) includes the following steps:

[0006] Based on safe distance constraints, determine the flight segments where each drone gets too close to other drones;

[0007] Based on a mixed-integer linear programming model, the conflict resolution constraints of existing and potential conflicts are coordinated, and a conflict resolution strategy for each UAV based on the departure time adjustment is determined.

[0008] Furthermore, the determination of flight segments where each UAV gets too close to other UAVs based on safe distance constraints includes:

[0009] Establish a set of route conflict checks;

[0010] The flight segments of two drones are expressed as functions of the time variable t; the departure times of the two drones are made the same through time alignment; and the conflict between drones is detected by the relationship between the initial relative position and relative speed of the drones.

[0011] Select the UAV segment with the earliest end time in the flight path conflict check set, and check the conflict between this segment and other segments one by one; when the conflict check between this segment and all other segments in the set is completed, remove this segment from the set, find the next segment of the UAV corresponding to this segment and put it into the check queue to form a new flight path conflict check set, and continue to perform conflict detection; if a conflict is found during the conflict check process, the relevant information of the segment involved in the conflict is recorded in the conflict set for further analysis.

[0012] Furthermore, the establishment of the route conflict check set includes:

[0013] Define drone A i The routes constitute a time-ordered segment queue I. i ={I i1 I i2 …I im};

[0014] Take out the first segment of each drone in sequence and put it into the check set; then find the segment with the earliest end time and check it with other segments in pairs; after the check is completed, take the segment out of the set, then add the next segment of the segment to the route conflict check set, and again select the segment with the earliest end time and check it with other segments in the set. Iterate in this way until all segments of all drones have been checked.

[0015] Furthermore, the step of aligning the departure times of the two drones through time alignment includes:

[0016] When the start times of the two flight segments are different, extend the flight segment with the later start time in the reverse direction until the start times of the two drones are the same:

[0017] Set P i o Let P be the starting point of the flight segment to be detected for the i-th UAV at this moment. i e The endpoint of the flight segment to be detected; for drones with a later departure time, their new starting point is determined as P after time alignment. i o ', equivalent to from P i o Point with velocity -v i exercised t io -t jo Duration.

[0018] Furthermore, the method of detecting collisions between drones by analyzing the relationship between their initial relative positions and relative velocities includes:

[0019] Assume that the drone needs to maintain a minimum distance of r from other drones during operation. s The straight-line distance; detection drone A i To A j First, calculate whether the shortest distance of the flight segment is less than the safe radius r. s When the shortest distance between two drones is less than r s Then, further conflict detection will be performed.

[0020] The specific testing steps are as follows:

[0021] Define drone A i The coordinates are P i (t)=(x i (t),y i (t)), Drone A j The coordinates are P j (t)=(x j (t),y j (t)); In the local coordinate system, define A i The initial position is the origin, and we obtain A. j The initial coordinates are:

[0022] P′ j =P j -P i

[0023] Assuming the drone maintains a constant speed, then v i,x and v i,y Representing drone A i Calculate A based on the velocity components along the x and y axes. i Compared to A j The speed of the motion is v′ i :

[0024]

[0025] Get A i Relative to A j Motion speed (v′) i,x ,v′i ,y After time t, A i The coordinates are (v′) i,x t,v′ i,y t); Calculate A i and A j The distance between them is r s r at time:

[0026]

[0027] Transforming the formula, we get:

[0028]

[0029] make

[0030] When Δ>0, the solution is When Δ = 0, At this moment, there is only a brief instant when the distance between the two drones equals the critical safe distance r; when Δ < 0, there is no t such that the distance between drones Ai and Aj is less than r. s ;

[0031] Define existing and potential conflicts: based on drone A i With A j According to the established flight plan, the distance between the two drones during flight may be less than the safe distance r. s In this situation, the conflict is defined as an existing one; according to drone A i With A j According to the established flight plan, the two drones will not be less than the safe distance r between them during flight. s However, if a time adjustment window [-T, T] is set, and the flight plans of the two drones are advanced or delayed by a certain amount of time within the time adjustment window, it will cause them to fly at a distance less than the safe distance r. s In such cases, this situation is defined as a potential conflict;

[0032] Define segment A i and A j The start times are t io and t jo The termination time is t ie and t je ;

[0033] (1) Analyze potential conflict risks:

[0034] a) If t has two solutions:

[0035] When (t) io ,t ie )∩(t jo ,t je When t = 0, it means that the flight plans of the two drones have no time overlap under the given scheme. Since t has solutions t1 and t2, it means that the potential conflict may be transformed into an existing conflict due to time adjustment.

[0036] When (t) io ,t ie )∩(t jo ,t je When A ≠ 0, it indicates that there exists a period of time A. i and Aj Both are in flight; however, if the earliest termination time of the two segments is earlier than the detected conflict time, it indicates that the drone turned before the conflict occurred, which is min(t). ie ,t je If the latest start time of the two flight segments is later than the detected conflict time, it means that the conflict did not occur due to the flight time difference, that is, t1,t2≤max(t1,t2); io ,t jo However, adjusting the takeoff time of the two drones could turn a potential conflict into an existing one.

[0037] b) If t has no solution or t has only one solution, since the shortest distance between the two UAVs entering the detection is less than the safe distance, there is a time difference between the arrival times of the two UAVs in the conflict zone, so no conflict occurs. However, due to time adjustment, the potential conflict may be transformed into an existing conflict.

[0038] (2) Analyze existing conflict risks:

[0039] a) If t has two solutions:

[0040] When (t) io ,t ie )∩(t jo ,t je When A ≠ 0, it indicates that there exists a period of time A. i and A j Flying at the same time, then assuming (t) io ,t ie )∩(t jo ,t je ) = set K, K∩(t1,t2)≠0, indicating that at the same time (t1,t2) of the two drones, io ,t ie )∩(t jo ,t je There exists a period of time in the interval (t1, t2) such that drone A... i and A j A conflict occurred;

[0041] b) If t has no solution or t has only one solution:

[0042] At this point, there was a time difference between the arrival times of the two drones in the conflict zone, so no conflict occurred.

[0043] Furthermore, the method of coordinating the resolution constraints of existing and potential conflicts based on the mixed-integer linear programming model, and determining the conflict resolution strategy for each UAV based on the departure time adjustment, includes:

[0044] To resolve existing conflicts between two drones;

[0045] Obtain constraints for potential conflict between two drones;

[0046] To resolve conflicts involving multiple drones.

[0047] Furthermore, the resolution of the conflict between the two drones includes:

[0048] If target drone A i and drone A j The flight paths of the drones conflicted, so the drone A was adjusted. i and A j The departure time variable, so that drone A j Leave the original conflict zone.

[0049] Furthermore, the process of obtaining constraints for potential conflict between two drones includes:

[0050] If there is a potential conflict between two drones, unreasonable timing adjustments may cause the potential conflict to develop into an actual conflict, thereby expanding the scope of the airspace conflict. Therefore, it is necessary to determine the constraints that the flight path adjustments of the two drones involved in the potential conflict must follow.

[0051] Furthermore, the conflict resolution for multiple drones includes:

[0052] When performing pairwise checks on n UAV segments, a constraint set of existing and potential conflicts is obtained for each UAV segment; where n is an integer greater than 2.

[0053] A mixed-integer linear programming model is established by combining all constraints, and the model is further solved to obtain the adjustment time.

[0054] Consider drone A i and A j There are multiple flight segments, so it is necessary to consider the potential or existing conflicts that may occur in multiple flight segments of the drone.

[0055] Another technical solution adopted in this invention is:

[0056] A multi-UAV offline flight path conflict detection and resolution device includes:

[0057] At least one processor;

[0058] At least one memory for storing at least one program;

[0059] When the at least one program is executed by the at least one processor, the at least one processor implements the method described above.

[0060] Another technical solution adopted in this invention is:

[0061] A computer-readable storage medium storing a processor-executable program, which, when executed by a processor, performs the method described above.

[0062] The beneficial effects of this invention are: This invention provides a multi-UAV offline flight path conflict detection and resolution scheme based on time variable description, which can take into account both the safe spacing of UAVs flying in congested environments and air traffic efficiency. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following description is provided with accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic diagram illustrating conflict detection segment by segment in an embodiment of the present invention;

[0065] Figure 2 This is a time alignment diagram in an embodiment of the present invention;

[0066] Figure 3 This is a schematic diagram of conflict detection in an embodiment of the present invention;

[0067] Figure 4 This is a schematic diagram illustrating the existing conflict between tangent constraints and endpoint constraints in an embodiment of the present invention; wherein, Figure 4 (a) is a schematic diagram of existing conflicts of tangent constraints. Figure 4 (b) is a schematic diagram of existing conflicts with endpoint constraints;

[0068] Figure 5 This is a schematic diagram illustrating the potential conflict between tangent constraints and endpoint constraints in an embodiment of the present invention; wherein, Figure 5 (a) is a schematic diagram of potential conflicts of tangent constraints. Figure 5 (b) is a schematic diagram of potential conflicts of endpoint constraints;

[0069] Figure 6 This is a flowchart of a method for detecting and resolving offline flight path conflicts of multiple UAVs based on time variables, as described in an embodiment of the present invention. Detailed Implementation

[0070] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0071] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0072] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0073] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0074] See Figure 6 This embodiment provides a method for offline flight path conflict detection and resolution of multiple unmanned aerial vehicles (UAVs) based on time variable description. This method can balance the safe spacing of UAVs flying in congested environments with air traffic efficiency. The method specifically includes the following steps:

[0075] S1. Determine the flight segments where each UAV gets too close to other UAVs based on safe distance constraints.

[0076] like Figure 1 As shown, the flight path of UAV A1 is defined as a time-ordered segment queue I1 = {I 11 I 12 …I 1m1 Similarly, if there are n drones, the flight paths for these n drones can be defined in the same way.

[0077] Establish a flight path conflict check set. First, extract the first flight segment of each UAV in sequence and add it to the check set. Then, find the flight segment with the earliest end time and check it pairwise with all other flight segments. After checking, remove the flight segment from the set, then add the next flight segment of that segment to the flight path conflict check set, and again select the flight segment with the earliest end time and check it with all other flight segments in the set. Iterate in this way until all flight segments of all UAVs have been checked.

[0078] When inspecting two drone flight segments, it's necessary to consider that each segment has a different start and end time. Based on these differences, the start times of the two drone flight segments are aligned to have the same starting point. For example... Figure 2 As shown, when the start times of two flight segments are different, the segment with the later start time is extended in the reverse direction. The flight segments discussed in this paper are all straight segments; therefore, the segment to be extended can be extended in the reverse direction until the start times of the two UAVs are the same. Let P be... i o Let P be the starting point of the flight segment to be detected for the i-th UAV at this moment. i e This is the endpoint of the flight segment to be detected. For drones with a later departure time, their new starting point is determined as P after time alignment. i o' This is equivalent to starting from P. i o Point with velocity -v i exercised t io -t jo Duration.

[0079] Assume that the drone needs to maintain a minimum distance of r from other drones during operation. s The straight-line distance. Detecting drone A i To A j First, calculate whether the shortest distance of the flight segment is less than the safe radius r. s When the shortest distance between the two drones is less than r s Then, further conflict detection will be performed.

[0080] When the shortest distance between the two drones is greater than or equal to r s At that time, the two drones will not conflict in the corresponding flight segment and will not enter the next stage of conflict detection.

[0081] Based on this, the flight segments of the two drones are expressed as functions of the time variable t. After aligning the departure times of the two drones to be the same, collisions between the drones can be detected by the relationship between their initial relative positions and relative velocities.

[0082] Define drone A i The coordinates are Pi (t)=(x i (t),y i (t)), Drone A j The coordinates are P j (t)=(x j (t),y j (t)).

[0083] See Figure 3 In the local coordinate system, define A i If the initial position is the origin, then A j The initial coordinates are:

[0084] P′ j =P j -P i

[0085] Assuming the drone maintains a constant speed, then v i,x and v i,y Representing drone A i The velocity components along the x-axis and y-axis, for A j Similarly, at this time A i Compared to A j The speed of motion is:

[0086]

[0087] A i Relative to A j The velocity of the motion is (v′) i,x ,v′ i,y After time t, A i The coordinates are (v′) i,x t,v′ i,y t).

[0088] Calculate A i and A j The distance between them is r s The equation is:

[0089]

[0090] The above equation is a quadratic equation in one variable.

[0091]

[0092] Substitute the above equation Δ=b 2 -4ac.

[0093] When Δ>0, the solution is When Δ = 0, At this moment, there is only a brief instant when the distance between the two drones equals the critical safe distance r; when Δ < 0, there is no t such that drone A i and A j The distance between them is less than r s .

[0094] First, define existing conflicts and potential conflicts. According to A... i With A j According to the established flight plan, during the flight, the distance between them will be less than the safe distance r. s In this situation, the situation is defined as an existing conflict; according to A i With A j According to the established flight plan, they will not be less than the safe distance r between them during flight. s However, if a time adjustment window [-T, T] is set, and the flight plans of the two drones are advanced or delayed by a certain amount of time within the time adjustment window, it will cause them to fly at a distance less than the safe distance r. s In such cases, this situation is defined as a potential conflict.

[0095] Define segment A i and A j The start times are t io and t jo The termination time is t ie and t je .

[0096] Analyze potential conflict risks:

[0097] (1) If t has two solutions:

[0098] When (t) io ,t ie )∩(t jo ,t je When t = 0, it means that the flight plans of the two drones have no time overlap under the given scheme. Since t has solutions t1 and t2, it means that the potential conflict may be transformed into an existing conflict due to time adjustment.

[0099] When (t) io ,t ie )∩(t jo ,t je When A ≠ 0, it indicates that there exists a period of time A. i and A j Both are in flight. However, if the earliest termination time of the two segments is earlier than the detected conflict time, it means that the drone turned before the conflict occurred, which is min(t). ie ,t jeIf the latest start time of the two flight segments is later than the detected conflict time, it means that the conflict did not occur due to the flight time difference, that is, t1,t2≤max(t1,t2); io ,t jo However, adjusting the takeoff time of the two drones could turn a potential conflict into an existing one.

[0100] (2) If there is no solution for t or there is only one solution for t, since the shortest distance between the two UAVs entering the detection is less than the safe distance, there is a time difference between the arrival times of the two UAVs in the conflict zone, so no conflict occurs. However, due to time adjustment, the potential conflict may be transformed into an existing conflict.

[0101] Analyze existing conflict risks:

[0102] (1) If t has two solutions:

[0103] When (t) io ,t ie )∩(t jo ,t je When A ≠ 0, it indicates that there exists a period of time A. i and A j Flying at the same time, then assuming (t) io ,t ie )∩(t jo ,t je ) = set K, K∩(t1,t2)≠0, indicating that at the same time (t1,t2) of the two drones, io ,t ie )∩(t jo ,t je There exists a period of time in the interval (t1, t2) such that drone A... i and A j A conflict occurred.

[0104] (2) If t has no solution or t has only one solution:

[0105] At this point, there was a time difference between the arrival times of the two drones in the conflict zone, so no conflict occurred.

[0106] Once all flight segments in the flight path conflict check set have been checked for conflict, the flight segment with the fastest completion time is taken out, and the next flight segment of the corresponding UAV is found and added to the check queue to continue conflict detection. At the same time, if there is conflict information, the relevant flight path information involved in the conflict is recorded in the conflict set, and then the next step of analysis is carried out.

[0107] Similarly, collision detection can also be performed in three-dimensional space. Different methods can be used for different safe zones.

[0108] For cylindrical safe regions, a mapping method can be used to discuss the problem separately in the horizontal XY plane and the vertical Z-axis; for spherical safe regions, this algorithm can be directly extended to obtain good results.

[0109] S2. Based on the mixed-integer linear programming model, coordinate the resolution constraints of existing and potential conflicts, and determine the conflict resolution strategy for each UAV based on the departure time adjustment.

[0110] The maximum value for time adjustment is specified as T (T>0), indicating that there are limits to time adjustment. Define the time variable t. k ∈[-T,T], representing drone A k The adjustment amount for the start time. When t k When <0, it indicates that drone A k Start time delayed by t k seconds; when t k When >0, it indicates that drone A k Start time advanced by t k seconds; when t k When = 0, it indicates that drone A k The start time will not be adjusted.

[0111] According to A i and A j The distance relationship and specific flight segment conditions are defined as A. j The left and right safety boundary positions are defined, and a circle is drawn with the coordinates of these two positions as its center. s Draw a circle with radius , obtaining two safe circular regions. The tangent constraint and endpoint constraint are analyzed below. The tangent constraint is the inter-drone safety separation constraint when two UAV segments spatially intersect, in which case the shortest distance between the two UAVs may be 0, such as... Figure 4 As shown in (a). The endpoint constraint is that the two UAV segments do not intersect, but the shortest distance between the segments is less than r. s In this case, the constraints on the safe distance between drones. For example... Figure 4 As shown in (b), for ease of analysis, the analysis is still performed using relative velocity and position in a local coordinate system. A i Relative to A j The direction of the moving segment is related to v′ i Same, according to A i and A j The minimum distance p between the two segments determines A. i The end point of the relative flight segment.

[0112] To perform a unified analysis of tangent constraints and endpoint constraints, further analysis is required. For example... Figure 4As shown in (a), when two UAV segments intersect, to ensure that the minimum distance between the two UAVs is greater than or equal to r s A needs to be adjusted. j Its position makes it in such Figure 4 (a) is outside the line segment formed by the left and right safety boundary positions shown. Let a be A. i Flight segment and A j The angle of the flight segment. Relative velocity v′ i The line containing and A j The included angle on the flight segment is b. Assume A j If A's initial position is to the left of the relative velocity, then at this time... j The distance from the left safety circle is Δx = Δl / sinb, where Δl = r s -d, d is A j Initial position to relative velocity v′ i The perpendicular distance to the line in question. Simultaneously, half the distance between the left and right safety boundary positions can be determined as L = r. s / sinb. The same method can be used to analyze when A... j The case where the initial position is to the right of the relative velocity.

[0113] like Figure 4 As shown in (b), when the flight segments of the two drones do not intersect, A i With A j The shortest vertical distance of the flight segment is s min To ensure that the minimum distance between two drones is greater than or equal to r s A needs to be adjusted. j Its position makes it in such Figure 4 (b) Outside the line segment formed by the left and right safety boundary positions shown. At this point, half the distance between the left and right safety boundary positions can be determined. Assume A j The initial position is at the relative end of the flight segment to A. j If the vertical foot of segment A is to the left of p, then at this time A j The distance from the left safety circle is Δx = Ld, where d is A j Initial position to A i Relative segment endpoint to A j The distance from point p, the foot of the perpendicular, to the flight segment. The same method can be used to analyze when A... j The case where the initial position is to the right of the relative velocity.

[0114] In the subsequent analysis, we will use Δx and L to uniformly describe the problems of tangent constraints and endpoint constraints.

[0115] S21. Resolving existing conflicts between two drones. Assume target drone A... i and A j The flight paths of the two UAVs conflict with each other. This paper discusses how to adjust the time variable to achieve a safe distance between the two UAVs during flight.

[0116] (1) When A j When the position is on the left:

[0117] Simultaneously adjust A i and A j The departure start time makes A j Leaving the original conflict zone. This allows A to... j The position point is adjusted to the left along its predetermined flight segment. At this time, A j The distance from the left safety circle is Δx. Adjust A. i and A j Departure time t i and t j To achieve effect A j Relative to A in its flight segment direction i Adjusting Δx to the left, then A j The position is exactly at the left safety boundary, at which point v i cosat i -v j t j =Δx, after adjustment A i and A j The minimum distance between them increases to be greater than or equal to the safe distance, at which point A i and A j The conflict was resolved.

[0118] It should be noted that in the constraint analysis after conflict resolution in this embodiment, the value of t can be positive or negative. When t is negative, it means that the start time is delayed by t seconds; when t is positive, it means that the start time is advanced by t seconds.

[0119] When A j Relative to A i Move to the left by at least Δl / sinb, expressed as: v j t j -v i cosat i ≤-Δx, rearranged, we obtain the conflict resolution constraint:

[0120] v i cosat i -v j t j ≥Δx

[0121] It is also possible to let A jAdjust to the right to move away from the excessively close interval, at which point A j The position relative to the right safety boundary is 2L-Δx. Adjust A. i and A j Departure time t i and t j To achieve effect A j Relative to A in its flight segment direction i Adjust 2L-Δx to the right so that A j The initial position is exactly on the right safety boundary, at which point v j t j -v i cosat i =2L-Δx, after adjustment A i and A j The minimum distance between them increases and exceeds the safe distance. At this time, A i and A j The conflict resolution constraints are:

[0122] -(v i cosat i -vjtj)≥2L-Δx

[0123] (2) When A j When the position is on the right:

[0124] Simultaneously adjust A i and A j The start time makes A j It can break away from the original conflict zone. This allows A to... j Adjust to the left to move away from the excessively close interval, at which point A j The distance from the left safety circle is 2L-Δx. At A j In the direction of the flight segment, when A j Relative to A i Move 2L-Δx to the left, and if v is satisfied at this point... i cosat i -v j t j =2L-Δx, then A j A's initial position is exactly at the left safety boundary. j and A i The minimum distance increases, therefore A i and A j The conflict resolution constraints are:

[0125] v i cosat i -v j t j ≥2L-Δx

[0126] It is also possible to let A j Adjust to the right to escape the conflict zone; at this point, A j The distance from the safety circle on the right is Δx. At A j In the direction of the flight segment, when A j Relative to A i Adjust Δx to the right, at which point v j t j -v i cosat i =Δx, A j It is exactly at the right safety boundary position, thus ensuring A j and A i The minimum distance increases to be greater than or equal to the safe distance, at which point A... i and A j The conflict resolution constraints are:

[0127] -(v i cosat i -v j t j )≥Δx

[0128] S22, Constraints for potential conflict between two drones.

[0129] When a potential conflict exists between two drones, inappropriate timing adjustments could cause the potential conflict to escalate into an actual conflict, thereby expanding the scope of the airspace conflict. Therefore, it is necessary to consider the constraints that potential conflicts impose on the flight path adjustments of each drone.

[0130] To provide a unified analysis of tangent constraints and endpoint constraints, further analysis is conducted. For example... Figure 5 As shown in (a), when two UAV segments intersect, in order to ensure that the minimum distance between the two UAVs is greater than or equal to r s It is necessary to ensure A j Its position prevents it from entering, such as Figure 5 (a) is the line segment formed by the left and right safety boundary positions shown. Let a be A. i Flight segment and A j The angle of the flight segment. Relative velocity v′ i The line containing and A j The included angle on the flight segment is b. Assume A j If the initial position of A is to the left of the relative velocity, then at this time... j The distance from the left safety circle is Δx = Δl / sinb, where Δl = dr s d is A j Initial position to relative velocity v′ iThe perpendicular distance to the line containing the boundary. Half the distance between the left and right safety boundary positions can be determined as L = r / sinb. The same method can be used to analyze when A... j The case where the initial position is to the right of the relative velocity.

[0131] like Figure 5 As shown in (b), when the flight segments of the two drones do not intersect, A i With A j The shortest vertical distance of the flight segment is s min To ensure that the minimum distance between two drones is greater than or equal to r s It is necessary to ensure A j Its position prevents it from entering, such as Figure 5 (b) Outside the line segment formed by the left and right safety boundary positions shown. At this point, half the distance between the left and right safety boundary positions can be determined. Assume A j The initial position is at the relative end of the flight segment to A. j If the vertical foot of segment A is to the left of p, then at this time A j The distance from the left safety circle is Δx = dL, where d is A. j Initial position to A i The distance between the endpoint of the relative flight segment and the perpendicular point p of flight segment Aj. The same method can be used to analyze when A... j The case where the initial position is to the right of the relative velocity.

[0132] Assume target drone A i and A j The flight paths of the two UAVs may conflict. The constraints that should be followed to ensure a safe distance between them during flight are discussed.

[0133] (1) When A j When the position is on the left:

[0134] Simultaneously adjust A i and A j The start time makes A j Do not enter the conflict segment. At this time, A j The distance from the left safety boundary is Δx. When A j The initial position relative to A i If we move Δx to the right, then A j Just at the left safety boundary position, at this time v j t j -v i cosat i =Δx, when A j Continue moving relatively to the right, A jand A i If the minimum distance is less than the safe distance, the potential conflict between the two drones becomes an existing conflict. Therefore, A j Relative to A i The displacement to the right cannot exceed Δx. The potential constraint is:

[0135] -(v i cosat i -v j t j )≤Δx

[0136] When v i cosat i -v j t j When >0, i.e., v j t j -v i cosat i When <0, it means A j Relative to A i Move to the left, A j and A i As the distance increases, the two drones will not get too close.

[0137] Or, A j The distance from the right safety boundary is 2L+Δx, when A j The initial position relative to A i Move 2L + Δx to the right, then A j Just at the right safety boundary position, at this time v j t j -v i cosat i = 2L + Δx. When v j t j -v i cosat i <2L+Δx, at this time A j They entered the conflict zone. Therefore, the potential conflict between the two drones became an existing conflict, hence A... j Relative to A i The displacement to the right cannot be less than 2L + Δx:

[0138] -(v i cosat i -v j t j )≥2L+Δx

[0139] When A j The initial position moves to the right satisfying constraint v j t j -v i cosati With a speed of >2L+Δx, the two drones will not get too close.

[0140] (2) When A j When the position is on the right:

[0141] Simultaneously adjust A i and A j The start time of A makes A j Do not enter the conflict segment. At this time, A j The distance from the right safety circle is Δx. When A j The initial position relative to A i If we move Δx to the left, then A j Just at the right safety boundary position, at this time v j t j -v i cosat i =-Δx. When A j The initial position continues to move relatively to the left, at which point v j t j -v i cosat i <-Δx, A j Upon entering the conflict zone, the potential conflict transforms into an existing conflict. Therefore, A j Relative to A i The initial displacement to the left cannot exceed Δx:

[0142] -(v i cosat i -v j t j )≥-Δx

[0143] When-Δx <v j t j -v i cosat i When <0, A j Relative to A i The initial displacement to the left does not exceed Δx, preventing excessive proximity. When v j t j -v i cosat i When >0, A j Relative to A i Move to the right, A j and A i With increased distance, excessive closeness will not occur.

[0144] Or, A j The distance from the left safety circle is 2L+Δx, when A j Relative to A iMove left by 2L + Δx, then A j Just at the left safety boundary position, at this time v j t j -v i cosat i = -2L - Δx. When A j Continue moving relatively to the left, A j and A i With increased distance, excessive closeness will not occur.

[0145] -(v i cosat i -v j t j )≤-(2L+Δx)

[0146] S23, Conflict resolution for multiple drones.

[0147] In summary, when performing conflict checks on the flight segment sequences of n UAVs, a constraint set of existing and potential conflicts for each UAV's flight segment is obtained. Combining all constraints, a mixed-integer linear programming model is established. Further solving the model yields the adjustment time T = {t1, t2, ..., t...}. n As mentioned above, consider A. i and A j There are multiple flight segments, so it is also necessary to consider the potential or existing conflicts that may occur in multiple flight segments.

[0148] Define A j The Flight segment and A i The Relative speed of each segment The angle between the lines they lie on is By considering both tangent constraints and endpoint constraints in a unified manner, we can obtain... and Define A i and A j The included angle of the flight segment is

[0149] Given the four constraints analyzed above, the flight segments of the two UAVs can only satisfy one of the constraints. Define an integer variable... Describe this requirement, set At that time, A i and A j There is an established conflict, A j To the left of the relative velocity; At that time, A i and A j There is an established conflict, A j To the right of the relative velocity; At that time, Ai and A j There is a potential conflict, A j To the left of the relative velocity; At that time, A i and A j There is a potential conflict, A j To the right of relative velocity.

[0150] When c ij When = 3, choose or The two constraints, when applied to the model, result in:

[0151]

[0152] or

[0153]

[0154] M is an infinite real value. Because when c ij When t = {0, 1, 2}, the right side of the inequality equals an infinite number M, and the two constraints apply to t. i and t j It has no binding effect. If and only if c ij When =3, the right side of the inequality is and

[0155] When c ij Similarly, for {0,1,2}, the model is obtained from the above:

[0156]

[0157]

[0158] and The formulas correspond to two constraint schemes for the same type of conflict, when When ρ represents that the chosen option is selected, while the other option is not selected; i ρ represents the importance weight of each drone flight path. i The higher the value, the more important the drone's flight segment is, and it should not be over-adjusted.

[0159] This embodiment also provides a multi-UAV offline flight path conflict detection and resolution device, including:

[0160] At least one processor;

[0161] At least one memory for storing at least one program;

[0162] When the at least one program is executed by the at least one processor, the at least one processor implements Figure 6 The method shown.

[0163] This embodiment of the multi-UAV offline flight path conflict detection and resolution device can execute the multi-UAV offline flight path conflict detection and resolution method provided in the method embodiment of the present invention, and can execute any combination of implementation steps of the method embodiment, and has the corresponding functions and beneficial effects of the method.

[0164] This application also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, causing the computer device to perform... Figure 6 The method shown.

[0165] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this invention are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is altered and sub-operations described as part of a larger operation are executed independently.

[0166] Furthermore, although the invention has been described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the described functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the invention. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional skill of an engineer. Therefore, those skilled in the art can implement the invention as set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of the invention, which is determined by the full scope of the appended claims and their equivalents.

[0167] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0168] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0169] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0170] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0171] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0172] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0173] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for offline flight path conflict detection and resolution among multiple unmanned aerial vehicles (UAVs), characterized in that, Includes the following steps: Based on safe distance constraints, determine the flight segments where each drone gets too close to other drones; Based on a mixed-integer linear programming model, the conflict resolution constraints of existing and potential conflicts are coordinated, and a conflict resolution strategy for each UAV based on the departure time adjustment is determined. The method for determining flight segments where each UAV gets too close to other UAVs based on safe distance constraints includes: Establish a set of route conflict checks; The flight segments of two drones are expressed as functions of the time variable t; the departure times of the two drones are made the same through time alignment; and the conflict between drones is detected by the relationship between the initial relative position and relative speed of the drones. Select the UAV segment with the earliest end time in the flight path conflict check set, and check the conflict between this segment and other segments one by one; when the conflict check between this segment and all other segments in the set is completed, remove this segment from the set, find the next segment of the UAV corresponding to this segment and put it into the check queue to form a new flight path conflict check set, and continue to perform conflict detection; if a conflict is found during the conflict check process, the relevant information of the conflicting flight segments is recorded in the conflict set for further analysis; The establishment of the route conflict check set includes: Define drone A i The routes constitute a time-ordered segment queue I. i ={I i1 I i2 …I im }; Take out the first segment of each drone in sequence and put it into the check set; then find the segment with the earliest end time and check it with other segments in pairs; after the check is completed, take the segment out of the set, then add the next segment of the segment to the route conflict check set, and again select the segment with the earliest end time and check it with other segments in the set. Iterate in this way until all segments of all drones have been checked.

2. The method for offline flight path conflict detection and resolution of multiple unmanned aerial vehicles according to claim 1, characterized in that, The method of aligning the departure times of the two drones to be the same includes: When the start times of the two flight segments are different, extend the flight segment with the later start time in the reverse direction until the start times of the two drones are the same: set up Let be the starting point of the flight segment to be detected for the i-th UAV at this moment. The endpoint of the flight segment to be tested; for drones with later departure times, their new starting point is determined after time alignment. equivalent to from Point by speed Exercise Duration.

3. The method for detecting and resolving offline flight path conflicts of multiple unmanned aerial vehicles according to claim 1, characterized in that, The method of detecting collisions between drones by analyzing the relationship between their initial relative positions and relative velocities includes: Assuming the drone needs to maintain minimal distance from other drones during operation The straight-line distance; detection drone A i To A j First, calculate whether the shortest distance of the flight segment is less than the safe radius. When the shortest distance between the two drones is less than Then, further conflict detection will be performed. The specific testing steps are as follows: Define drone A i The coordinates are Drone A j The coordinates are ; In the local coordinate system, define A i The initial position is the origin, and we obtain A. j The initial coordinates are: Assuming the drone maintains a constant speed, then and Representing drone A i Calculate A based on the velocity components along the x and y axes. i Compared to A j The speed of the movement is : Get A i Relative to A j Speed ​​of movement ( After time t, A i The coordinates are A was calculated. i and A j The distance between them is time : Transforming the formula, we get: make , , , ; when When, it is interpreted as , ;when hour, At that moment, the distance between the two drones was equal to the critical safe distance for only a split second. ;when When < 0, there is no t such that the distance between drones Ai and Aj is less than 0. ; Define existing and potential conflicts: based on drone A i With A j According to the established flight plan, the two drones may drift apart during flight, with the distance between them falling below the safe distance. In this situation, the conflict is defined as an existing one; according to drone A i With A j According to the established flight plan, the two drones will not be less than the safe distance between them during flight. However, if a time adjustment window [-T, T] is set, and the flight plans of the two drones are advanced or delayed by a certain amount of time within the time adjustment window, it will cause them to fly at a distance less than the safe distance. In such cases, this situation is defined as a potential conflict; Define segment A i and A j The start times are respectively and The termination time is and ; (1) Analyze potential conflict risks: a) If t has two solutions: when The fact that the flight plans of the two drones do not overlap under the given scheme indicates that t has solutions t1 and t2, suggesting that the potential conflict may be transformed into an existing conflict due to time adjustments. when At that time, it indicates that there was a period of time A. i and A j Both were in flight; however, if the earliest termination time of both flight segments was earlier than the detected conflict time, it indicates that the drone turned before a conflict occurred, meaning... If the latest start time of the two flight segments is later than the detected conflict time, it means that the conflict did not occur due to the flight time difference. However, adjusting the takeoff time of the two drones could turn a potential conflict into an existing one. b) If t has no solution or t has only one solution, since the shortest distance between the two UAVs entering the detection is less than the safe distance, there is a time difference between the arrival times of the two UAVs in the conflict zone, so no conflict occurs. However, due to time adjustment, the potential conflict may be transformed into an existing conflict. (2) Analyze existing conflict risks: a) If t has two solutions: when At that time, it indicates that there was a period of time A. i and A j Flying at the same time, then assuming ( Set K, K This indicates that the two drones were operating simultaneously at the same time. It existed for a period of time The interval allows drone A to... i and A j A conflict occurred; b) If t has no solution or t has only one solution: At this point, there was a time difference between the arrival times of the two drones in the conflict zone, so no conflict occurred.

4. The method for detecting and resolving offline flight path conflicts of multiple unmanned aerial vehicles according to claim 1, characterized in that, The method based on a mixed-integer linear programming model coordinates the resolution constraints of existing and potential conflicts, and determines the conflict resolution strategy for each UAV based on departure time adjustments, including: To resolve existing conflicts between two drones; Obtain constraints for potential conflict between two drones; To resolve conflicts involving multiple drones.

5. The method for detecting and resolving offline flight path conflicts of multiple unmanned aerial vehicles according to claim 4, characterized in that, The resolution of conflicts between two drones includes: If target drone A i and drone A j The flight paths of the drones conflicted, so the drone A was adjusted. i and A j The departure time variable, so that drone A j Leave the original conflict zone.

6. The method for detecting and resolving offline flight path conflicts of multiple unmanned aerial vehicles according to claim 4, characterized in that, The process of obtaining constraints for potential conflict between two drones includes: If there is a potential conflict between two drones, unreasonable timing adjustments may cause the potential conflict to develop into an actual conflict, thereby expanding the scope of the airspace conflict. Therefore, it is necessary to determine the constraints that the flight path adjustments of the two drones involved in the potential conflict must follow.

7. The method for offline flight path conflict detection and resolution of multiple unmanned aerial vehicles according to claim 4, characterized in that, The conflict resolution for multiple drones includes: When performing pairwise checks on n UAV segments, a constraint set of existing and potential conflicts is obtained for each UAV segment; where n is an integer greater than 2. A mixed-integer linear programming model is established by combining all constraints, and the model is further solved to obtain the adjustment time. Consider drone A i and A j There are multiple flight segments, so it is necessary to consider the potential or existing conflicts that may occur in multiple flight segments of the drone.

8. A multi-UAV offline flight path conflict detection and resolution device, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method of any one of claims 1-7.

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