Urban vertical take-off and landing airport flight procedure design and evaluation method

Abstract

The application discloses a kind of urban vertical take-off and landing airport flight procedure design and evaluation method, comprising the following steps: step one: clear urban vertical take-off and landing airport flight procedure infrastructure and operation function, design multi-rotor unmanned aerial vehicle hover waiting strategy and dynamic right matrix planning algorithm flight procedure operation rule;Step two: establish flight procedure mathematical model, determine flight procedure necessary parameter, build optimal flight procedure structure;Step three: select flight procedure evaluation index, establish flight procedure evaluation system, analyze the safety and operating efficiency of flight procedure;Step four: analyze the influence of the first ring layer take-off point, ring layer total number, radius increment on flight procedure operating effect.The urban vertical take-off and landing airport flight procedure design and evaluation method used in the application can standardize the unmanned aerial vehicle operation of urban vertical take-off and landing airport, ensure operation safety and improve operation efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of flight program design and evaluation, and particularly relates to a flight program design and evaluation method for a city vertical take-off and landing airport in a city air traffic system. BACKGROUND

[0002] With the rapid development of low-altitude economy, the problem of multi-rotor unmanned aerial vehicle take-off and landing routes for city vertical take-off and landing airports gradually comes into people's field of vision. The city vertical take-off and landing airport flight program belongs to a part of the low-altitude air route, and connects the city vertical take-off and landing airport ground end and the low-altitude air space public air route. At present, there are few studies on the influence of the specific structure and parameters of the circular flight program on the operation effect, and secondly, the simulation operation scene of the multi-rotor unmanned aerial vehicle flight program does not comprehensively consider the operation effect of the city vertical take-off and landing airport flight program under different operation scenes, which will become problems that must be solved in the development of city air traffic. SUMMARY

[0003] The application aims to provide a city vertical take-off and landing airport flight program design and evaluation method, which can effectively solve the problems mentioned in the background and provide theoretical support for the optimization of subsequent actual application process.

[0004] The technical scheme of the application is as follows:

[0005] Step one: clearly define the basic structure of the city vertical take-off and landing airport flight program, clearly define the geometric layout and operation function of the take-off and landing points, and design the flight program operation rules based on the multi-rotor unmanned aerial vehicle hovering waiting strategy and the dynamic road right matrix Floyd shortest path planning algorithm based on time step.

[0006] Step two: establish a flight program mathematical model based on the first ring layer take-off and landing point, the total number of ring layers, and the radius increment, determine the necessary parameters of other flight programs, and construct the optimal flight program structure.

[0007] Step three: select flight program evaluation indexes, establish a flight program evaluation system, compare the safety and operation efficiency of the flight program under different city unmanned aerial vehicle traffic flow densities and operation modes, and select the flight program operation mode with better operation performance.

[0008] Step four: analyze the influence of the first ring layer take-off and landing point, the total number of ring layers, and the radius increment on the operation effect of the flight program, and compare and analyze the strategies for improving the operation efficiency of the mixed operation mode flight program.

[0009] Further, in step one, the urban vertical take-off and landing airport flight program includes explicit structural and geographical position information, the flight program is a ring layer nested three-dimensional structure, the vertical interval distance d between each ring layer is specified, d is in the range of 15-100m; the number of landing points in each ring layer is as follows:

[0010]

[0011] In the formula: i is the ring layer label, indicating the i ring layer; n i is the number of landing points in the i ring layer; is the integer part;

[0012] The central angle between two landing points is calculated as follows:

[0013]

[0014] The first ring layer landing points are uniformly distributed, and the angle between two landing points is the same; the layout of the i ring layer landing points depends on the layout of the i-1 ring layer landing points;

[0015] When the number of landing points is the same, draw n i radii with the ring layer center as the end point of the radius, each radius passes through a landing point on the i-1 ring layer; rotate the radius clockwise with the ring layer center as the rotation center, the rotation angle is Set n i landing points at the intersection of the radius and the i ring layer;

[0016] When the number of landing points in two ring layers is different, draw n radii with the center as the end point of the radius, each radius passes through a landing point on the i-1 ring layer, rotate each radius clockwise with the ring layer center as the rotation center, the rotation angle is Set n landing points at the intersection of the radius and the i ring layer; rotate each radius clockwise with the ring layer center as the rotation center, the rotation angle is θ i Set n landing points at the intersection of the radius and the i ring layer;

[0017] To ensure that the first ring layer has enough space to accommodate a certain amount of unmanned aerial vehicles, set the radius of the first ring layer to a specific value, and the radii of the remaining ring layers increase by a specific amount in turn, so the radius of each ring layer is calculated as follows:

[0018]

[0019] In the formula: r iRi is the radius of the ith ring layer; r1 is the first ring layer radius; when Δr = 0, the flight procedure is a cylindrical structure, and when Δr > 0, the flight procedure is an inverted circular table structure with the upper part being wide and the lower part being narrow.

[0020] Further, in step one, the urban vertical take-off and landing airport flight procedure includes take-off and landing points that undertake take-off and landing tasks, the take-off and landing points are connected to different ring layers and are traffic hubs of the ring layers, and the multi-rotor unmanned aerial vehicle can ascend or descend to an adjacent ring layer along a fixed route at the take-off and landing point or can move to other routes in the same ring layer by jumping between route points; the flight procedure defines a circulating route and a transfer route, layout rules of the two types of routes are designed respectively; the unmanned aerial vehicle maintains a minimum safety interval in the flight procedure; the unmanned aerial vehicle completes an approach flight task or a departure flight task in the flight procedure, in the approach flight task, the unmanned aerial vehicle enters from a take-off and landing point in the outermost ring layer to a specific take-off and landing point in the first ring layer; in the departure flight task, the unmanned aerial vehicle departs from a take-off and landing point in the first ring layer to a specific take-off and landing point in the outermost ring layer; the unmanned aerial vehicle follows a flight procedure operation rule based on a time step-based dynamic right-of-way matrix Floyd shortest path planning algorithm in the flight procedure.

[0021] Further, the circulating route is a route between two take-off and landing points in the current ring layer, and the unmanned aerial vehicle flies along the route in the same ring layer; the transfer route is a route between two route points in different ring layers, and the unmanned aerial vehicle transfers between ring layers through this type of route.

[0022] Further, the unmanned aerial vehicle has a mixed operation mode, an approach operation mode, and a departure operation mode in the flight procedure, in order to ensure the safety of the system operation of the flight procedure, the multi-rotor unmanned aerial vehicle has the following hovering waiting strategies:

[0023] (1) In the approach operation mode, the unmanned aerial vehicle departs from a low-altitude public route and descends along the flight procedure to the ground section of the urban vertical take-off and landing airport;

[0024] (2) In the departure operation mode, the unmanned aerial vehicle takes off from the ground end of the urban vertical take-off and landing airport and flies to a public low-altitude route;

[0025] (3) In the mixed operation mode, the approach unmanned aerial vehicle and the departure unmanned aerial vehicle fly simultaneously; the approach unmanned aerial vehicle departs from a low-altitude public route and descends along the flight procedure to the ground section of the urban vertical take-off and landing airport; the departure unmanned aerial vehicle takes off from the ground end of the urban vertical take-off and landing airport and flies to a public low-altitude route;

[0026] (4) In the circulating route, the unmanned aerial vehicle flies in the same direction in the counterclockwise direction;

[0027] (5) In the transfer route, only the UAVs are allowed to fly in a single direction; in the approach operation mode, the UAVs climb along the route; in the departure operation mode, the UAVs descend along the route; in the mixed operation mode, the flight direction of the UAVs in a single transfer route needs to be clear, the transfer routes for the UAVs to climb and the transfer routes for the UAVs to descend are staggered in turn, and in the adjacent two transfer routes, one transfer route is for the UAVs to climb and the other route is for the UAVs to descend;

[0028] (6) In order to ensure the safe operation of the flight program, the distance between the two UAVs needs to meet the minimum safety interval requirement during the operation of the flight program;

[0029] (7) If the minimum safety interval is not met when the two UAVs enter the route from the take-off and landing point, the UAV that is farther from the take-off and landing point hovers in place and waits until the minimum safety interval between the two UAVs is restored;

[0030] (8) If the minimum safety interval is not met during the flight of the UAV in the route, the UAV on the rear side of the flight program operation direction hovers in place and waits until the minimum safety interval is met before continuing to fly.

[0031] Further, the Floyd shortest path planning algorithm based on the time step dynamic right matrix is as follows:

[0032] (1) Determine whether a path exists from the take-off and landing point numbered i to the take-off and landing point numbered j, mark the existing path as l ij , add it to the set L, and calculate the path length c ij of l ij ;

[0033] (2) Construct an N×N dynamic right matrix W Road , and the calculation method of the elements in the dynamic right matrix is as follows:

[0034]

[0035] (3) Construct an N×N dynamic right matrix W Road , and the calculation method of the elements in the dynamic right matrix is as follows:

[0036] A[i,j]=G Road [i,j]+W Road [i,j]

[0037] In the formula, W Road [i,j] is the dynamic right of the route from the i th take-off and landing point to the j th take-off and landing point; w Road is the weight of a single UAV; n UAV is the number of UAVs on the route from the i th take-off and landing point to the j th take-off and landing point;

[0038] The expression of the dynamic right-of-way matrix A is as follows:

[0039] A[i,j]=G Road [i,j]+W Road [i,j]

[0040] (4) When the UAV reaches a landing point in the flight program except for the termination landing point, update the dynamic right-of-way matrix W based on the time step Road , calculate the remaining optimal flight segment of the UAV under the dynamic right-of-way matrix A using the Floyd algorithm.

[0041] Further, in step two, the construction of the mathematical model takes the maximum capacity of the flight program and the minimization of the theoretical flight range of the UAV in the flight program as indicators; the mathematical model is as follows:

[0042]

[0043] In the formula: l is the length of a single route segment; d safe is the minimum safety interval; θ safe is the minimum safety central angle; n1 is the number of landing points in the first ring layer; I is the total number of ring layers; Δr is the radius increment.

[0044] Further, in step three, the safety aspect takes the waiting time of the UAV entering the waiting state due to approaching the minimum safety interval as an indicator; the UAV exceeding the acceptable waiting time range is an unsafe UAV, and the flight program running efficiency is evaluated based on the number of unsafe UAVs; the flight time of the UAV in the flight program is taken as an indicator of the running efficiency; the greater the proportion of short flight time UAVs is, the higher the running efficiency of the flight program is.

[0045] Further, the starting time interval of the UAV executing the flight program obeys an exponential distribution, and the expression is as follows:

[0046]

[0047] In the formula: λ is the number of UAVs arriving at the flight program per unit time; the larger λ is, the shorter the time interval between two UAVs is, and the more concentrated the UAV traffic flow is; the flight program start time of each UAV is obtained by sequentially stacking the time intervals, and the running data of the UAV under the parameters λ=0.5, 0.75, 1, 1.25 are calculated respectively.

[0048] Further, in step four, the flight data of the unmanned aerial vehicle in the mixed operation mode, the approach operation mode and the departure operation mode are taken as the control group, the flight program structure parameters in the mixed operation mode are adjusted, the influence of the number of take-off and landing points, the total number of ring layers and the radius increment of the first ring layer on the operation safety and flight efficiency of the unmanned aerial vehicle is analyzed, so that the operation safety and flight efficiency of the unmanned aerial vehicle in the mixed operation mode are improved; the number of risk unmanned aerial vehicles under different parameter conditions is calculated to analyze the influence on the operation safety of the flight program; the average flight time of the unmanned aerial vehicle is calculated, and the number of unmanned aerial vehicles completing the flight task within a certain time is counted to evaluate the influence of the structure parameters on the operation efficiency of the unmanned aerial vehicle.

[0049] The beneficial effects of the present application are that the present application adopts a flight program design and evaluation method for urban vertical take-off and landing airports, solves the related problems mentioned in the background art, simultaneously realizes the operation safety guarantee problem of the unmanned aerial vehicle in the approach and departure, and improves the operation efficiency, thereby laying a foundation for subsequent urban vertical take-off and landing airport construction. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The flowchart of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application.

[0051] Figure 2 The flight program structure design schematic diagram of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application.

[0052] Figure 3 The two-ring layer layout schematic diagram of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application, wherein the left drawing is a two-ring layer layout schematic diagram with the same number of take-off and landing points, and the right drawing is a two-ring layer layout schematic diagram with different numbers of take-off and landing points.

[0053] Figure 4 The transfer route layout schematic diagram of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application, wherein the left drawing is a two-ring layer transfer route layout schematic diagram with different numbers of take-off and landing points, and the right drawing is a two-ring layer transfer route layout schematic diagram with the same number of take-off and landing points.

[0054] Figure 5 The NSGA-II optimization effect diagram of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application.

[0055] Figure 6 The mixed operation mode flight program structure of the embodiment of the flight program design and evaluation method for urban vertical take-off and landing airports of the present application.

[0056] Figure 7The application provides a flight procedure design and evaluation method for a city vertical take-off and landing airport.

[0057] Figure 8 The application provides a flight procedure design and evaluation method for a city vertical take-off and landing airport. DETAILED DESCRIPTION

[0058] The technical solution of the application is further described in the drawings and examples

[0059] Unless otherwise defined, the technical terms or scientific terms used in the application should be understood as the common meanings understood by those skilled in the art to which the application belongs.

[0060] EMBODIMENT

[0061] The application provides a flight procedure design and evaluation method for a city vertical take-off and landing airport, which comprises the following steps: Figure 1 as shown in the figure, comprising the following steps:

[0062] Step 1: The flight procedure basic structure of the city vertical take-off and landing airport is determined, the geometric layout and operation function of the take-off and landing point are determined, and the flight procedure operation rules based on the multi-rotor unmanned aerial vehicle hovering waiting strategy and the dynamic road right matrix Floyd shortest path planning algorithm based on time step are designed. In the aspect of flight procedure structure design, the present example takes the 200m*200m*100m clearance airspace as an example, takes the light unmanned aerial vehicle in the "Provisional Regulations on Flight Management of Unmanned Aerial Vehicles" as the research object, and equips the unmanned aerial vehicle with necessary communication, navigation and monitoring equipment in the clearance airspace of the city vertical take-off and landing airport. Figure 2The structure of the flight procedure of the urban vertical take-off and landing airport with three ring layers is shown in the figure, which is defined as the first ring layer, the second ring layer and the third ring layer from inside to outside; the first ring layer is 15 m away from the ground, and the height difference between each ring layer is kept at 15 m. A take-off and landing point is arranged at a specific position in each ring layer. The take-off and landing point connects different ring layers and is the traffic hub of each ring layer. The multi-rotor unmanned aerial vehicle can ascend or descend to an adjacent ring layer along the fixed route at the take-off and landing point or move to other routes in the same ring layer. In the flight procedure, the unmanned aerial vehicle performs two types of flight tasks: approach flight task and departure flight task. In the approach flight task, the unmanned aerial vehicle enters from the take-off and landing point of the outermost ring layer to a specific take-off and landing point of the first ring layer. In the departure flight task, the unmanned aerial vehicle departs from the take-off and landing point of the first ring layer to a specific take-off and landing point of the outermost ring layer. The take-off and landing point of the outermost ring layer connects the flight procedure and the low-altitude air route network. The approach unmanned aerial vehicle is released from the low-altitude air route network and freely flies to the nearest take-off and landing point of the flight procedure. The departure unmanned aerial vehicle freely flies from the take-off and landing point of the outermost ring layer of the flight procedure to the initial route point of the low-altitude air route network. The take-off and landing point of the first ring layer undertakes the take-off and landing task. The departure unmanned aerial vehicle vertically takes off from the ground parking space to the take-off and landing point of the first ring layer to enter the flight procedure of the urban vertical take-off and landing airport. After completing the flight task, the approach unmanned aerial vehicle vertically lands at the take-off and landing point of the first ring layer to the ground parking space.

[0063] The number of take-off and landing points in each ring layer is shown in the following formula:

[0064]

[0065] In the formula, i is the ring layer label, indicating the ith ring layer; n i is the number of take-off and landing points in the ith ring layer; is the upward rounding.

[0066] The central angle between two take-off and landing points is calculated according to the following formula:

[0067]

[0068] The take-off and landing points of the first ring layer are uniformly distributed, and the angle between two take-off and landing points is the same. The layout of the take-off and landing points of the ith ring layer depends on the layout of the take-off and landing points of the ith-1 ring layer. Figure 3 The ring layer layout is shown in the following figure when the number of take-off and landing points in two ring layers is the same and different. When the number of take-off and landing points is the same, n i radial lines with the ring layer center as the end point are drawn, and each radial line passes through a take-off and landing point on the ith-1 ring layer. The radial line is rotated clockwise with the ring layer center as the rotation center, and the rotation angle is n i take-off and landing points are arranged at the intersection of the radial line and the ith ring layer. When the number of take-off and landing points in two ring layers is different, n Each ray passes through a take-off and landing point on the i-1 ring layer, and each ray is rotated clockwise with the center of the ring layer as the rotation center, and the rotation angle is θi-1. At the intersection of the ray and the i ring layer, set a take-off and landing point; and each ray is rotated clockwise with the center of the ring layer as the rotation center, and the rotation angle is θi. i At the intersection of the ray and the i ring layer, set a take-off and landing point.

[0069] Based on the layout of the take-off and landing points of the flight procedure, the air route in the flight procedure of the urban vertical take-off and landing airport is divided into two categories. One is the air route between two take-off and landing points in the current ring layer, and the unmanned aerial vehicle flies along the air route in the same ring layer, and this kind of air route is called a circulating air route. The other is the air route between two air route points in different ring layers, and the unmanned aerial vehicle transfers between ring layers through this kind of air route, and this kind of air route is called a transfer air route.

[0070] In order to ensure that the first ring layer has enough space to accommodate a certain amount of unmanned aerial vehicles, the radius of the first ring layer is set to a specific value, and the radii of the remaining ring layers are sequentially increased by a specific growth amount, so the radius calculation formula of each ring layer is as follows:

[0071]

[0072] In the formula: r i is the radius of the i ring layer; r1 is the radius of the first ring layer. When Δr=0, the flight procedure is a cylindrical structure, and when Δr>0, the flight procedure is a reverse circular truncated cone structure with the top being wide and the bottom being narrow.

[0073] In terms of flight procedure rules, based on the multi-ring structure of the flight procedure and the flight characteristics of the multi-rotor unmanned aerial vehicle, the application designs three flight procedure operation modes, which are: mixed operation mode, approach operation mode, and departure operation mode, as shown in Figures 6-8 In order to ensure the safe operation of the flight procedure system, the flight procedure operation rules are as follows:

[0074] (1) In the approach operation mode, the unmanned aerial vehicle separates from the low-altitude public air route and lands along the flight procedure to the ground section of the urban vertical take-off and landing airport.

[0075] (2) In the departure operation mode, the unmanned aerial vehicle takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude air route.

[0076] (3) In the mixed operation mode, the approach unmanned aerial vehicle and the departure unmanned aerial vehicle fly simultaneously. The approach unmanned aerial vehicle separates from the low-altitude public air route and lands along the flight procedure to the ground section of the urban vertical take-off and landing airport; the departure unmanned aerial vehicle takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude air route.

[0077] (4) In the circular route, the UAVs fly in the same direction in the counterclockwise direction.

[0078] (5) In the transfer route, only one direction is allowed for the UAVs to fly. In the approach operation mode, the UAVs climb along the route; in the departure operation mode, the UAVs descend along the route; in the mixed operation mode, the direction of the UAVs in the single transfer route needs to be clear, and the transfer routes for the UAVs to climb and the transfer routes for the UAVs to descend are staggered in turn, and in the adjacent two transfer routes, one is for the UAVs to climb and the other is for the UAVs to descend. Figure 4 The layout diagram of the transfer route for the two-ring layers with different numbers of take-off and landing points and the layout diagram of the transfer route for the two-ring layers with the same number of take-off and landing points.

[0079] (6) To ensure the safe operation of the flight program, the distance between the two UAVs needs to meet the minimum safety interval requirement during the operation of the flight program.

[0080] (7) If the two UAVs do not meet the minimum safety interval when entering the route from the take-off and landing point, the UAV that is farther from the take-off and landing point will hover in place until the minimum safety interval is restored.

[0081] (8) If the UAV does not meet the minimum safety interval during the flight in the route, the UAV that is behind the direction of the flight program will hover in place until the minimum safety interval is met and the flight can continue.

[0082] In terms of UAV route planning algorithm, the approach task and the departure task can be regarded as the shortest path problem from the initial take-off and landing point to the terminal take-off and landing point. This paper selects Floyd algorithm to solve this shortest path problem. Floyd algorithm uses dynamic programming to traverse all nodes in the network to find the shortest path between two points. Therefore, compared with other algorithms, Floyd algorithm can solve the shortest path problem of directed graph and network graph with negative weight. In order to fully utilize the advantages of flight program structure and avoid local congestion of flight program, this paper designs a dynamic route weight matrix Floyd shortest path planning algorithm based on time step, and the algorithm steps are as follows:

[0083] (1) Determine whether there is a path from point numbered i to point numbered j, and record the existing path as l ij , add it to set L, and calculate the path length c ij of l ij .

[0084] (2) Construct an N×N dynamic route weight matrix W Road , and the calculation method of the elements in the dynamic route weight matrix is as follows:

[0085]

[0086] (3) Constructing N x N dynamic route right matrix W Road The element calculation method in the dynamic route right matrix is as follows:

[0087] W Road [i,j] = w Road x n UAV

[0088] In the formula, W Road [i,j] is the dynamic route right of the flight route from the ith take-off and landing point to the jth take-off and landing point; w Road is the weight of a single unmanned aerial vehicle; and n UAV is the number of unmanned aerial vehicles on the flight route from the ith take-off and landing point to the jth take-off and landing point.

[0089] The expression of the dynamic route right matrix A is as follows:

[0090] A[i,j] = G Road [i,j] + W Road [i,j]

[0091] (4) When the unmanned aerial vehicle arrives at any take-off and landing point in the flight procedure except the terminal take-off and landing point, the dynamic route right matrix W Road is updated based on the time step, and the Floyd algorithm is used to calculate the remaining optimal flight segment of the unmanned aerial vehicle under the dynamic route right matrix A.

[0092] On the basis of the traditional Floyd algorithm, the time length required for the change of the flight state of the unmanned aerial vehicle is taken as the time step, and the dynamic route right is calculated to obtain the shortest path in the overall process of the flight task of the unmanned aerial vehicle. This can make the unmanned aerial vehicle avoid possible congestion of the flight segment, select a flight route with similar flight distance and fewer unmanned aerial vehicles to execute the flight procedure, thereby fully utilizing the multi-ring layer structure of the flight procedure system and improving the flight procedure operation safety and the flight efficiency of the unmanned aerial vehicle. If the Floyd algorithm based on the dynamic route right matrix cannot calculate a feasible solution for a certain unmanned aerial vehicle, that is, all the capacities of the available flight segments are saturated, the flight procedure of this configuration is considered to be overloaded, and the configuration needs to be replaced.

[0093] Step 2: Establish a flight procedure mathematical model based on the first ring layer take-off and landing point, the total number of ring layers, and the radius increment, determine the necessary parameters of the flight procedure, and construct the optimal flight procedure structure. This example takes Phantom4 as an example to expand the explanation with a safety interval of 5 m. The radius of the first ring layer is 20 m, the length of the circular flight route l i is calculated as follows:

[0094]

[0095] The transfer flight route length l i,i-1 from the take-off and landing point i to the take-off and landing point i-1 is calculated as follows:

[0096]

[0097] wherein: r i , r i-1 is the radius of the i-th ring layer and the i-1-th ring layer; z is the height difference between the two ring layers.

[0098] In terms of flight program capacity, the capacity of a single segment air route in the flight program is as follows:

[0099]

[0100] wherein: c road is the maximum capacity of the segment air route; l is the length of the segment air route; d safe is the minimum safety interval; represents the floor function.

[0101] Based on the minimum safety interval between two unmanned aerial vehicles and the radius of the ring layer, the minimum safety central angle between the two unmanned aerial vehicles can be obtained, that is, the minimum angle of the circular arc formed by the two unmanned aerial vehicles and the center of the ring layer under an acceptable safety level, and the calculation formula is as follows:

[0102]

[0103] wherein: θ safe is the minimum safety central angle.

[0104] Therefore, the capacity C circuit of a single ring layer circular air route in the flight program system is as follows:

[0105]

[0106] The capacity C divert of a single transfer air route from the i-th ring layer to the i-1-th ring layer is as follows:

[0107]

[0108] In order to ensure the capacity of the first ring layer circular air route, n1 should not be too large, and the upper limit of n1 is set to 8; in order to ensure the scheduling performance of the first ring layer, the lower limit of the take-off and landing points of the first ring layer is set to 2. The present application determines the value range of the radius increment Δr according to the extreme value of the theoretical maximum ring layer, i.e. the sixth ring layer.

[0109] Based on this, the mathematical model is obtained as follows:

[0110]

[0111] The values of the related parameters are shown in the following table:

[0112]

[0113] The Pareto front obtained based on the NSGA-II algorithm is shown in FIG. 1. Figure 5

[0114] Step three: selecting flight procedure evaluation indexes, establishing a flight procedure evaluation system, comparing the safety and operation efficiency of flight procedures in different urban unmanned aerial vehicle traffic flow densities and operation modes, and selecting a flight procedure operation mode with better operation performance. The flight procedure is evaluated from two dimensions of system safety and operation efficiency in the present application. The present application takes the number of risk unmanned aerial vehicles as an index to evaluate the safety of the flight procedure system. Although the collision probability reaches the maximum value when the unmanned aerial vehicle is close to the minimum safety interval, i.e. in an unsafe state, based on the overall operation time, the nature of unmanned aerial vehicle flight tasks, the actual operation of urban air traffic and other factors, the present application assumes that the total waiting time of the Phantom 4 model unmanned aerial vehicle during operation does not exceed 1s, i.e. within the acceptable range of actual operation safety, otherwise it is considered as a risk unmanned aerial vehicle. The length of the waiting time reflects the safety risk degree of the unmanned aerial vehicle during flight. When the distance between unmanned aerial vehicles is equal to the minimum safety interval, the unmanned aerial vehicle needs to perform a waiting procedure; when the distance between unmanned aerial vehicles is equal to the minimum safety interval, the probability of danger such as collision approaches the boundary of the acceptable range; the longer the waiting time of the unmanned aerial vehicle during flight, i.e. the longer the time of the unmanned aerial vehicle during operation within the boundary of the acceptable safety range, the higher the safety risk of the unmanned aerial vehicle operation.

[0115] The flight time of the unmanned aerial vehicle is selected as an index to represent the operation efficiency of the flight procedure. The calculation formula of the flight time of the unmanned aerial vehicle is as follows:

[0116]

[0117] The longer the flight time of the unmanned aerial vehicle, the lower the operation efficiency of the flight procedure. Based on the shortest flight time of the unmanned aerial vehicle in the flight procedure, the acceptable delay time is set, the proportion of the number of unmanned aerial vehicles within the acceptable delay time in the actual operation is counted, and the operation efficiency of the flight procedure is compared and analyzed.

[0118] ​Step four: analyze the influence of the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius increment on the flight procedure operation effect, and compare and analyze the strategy of improving the flight procedure operation efficiency in the mixed operation mode. The unmanned aerial vehicle flow under a specific traffic flow density is taken as the experiment, the unmanned aerial vehicle flight data in the mixed operation mode, the approach operation mode, and the departure operation mode are taken as the control group, the flight procedure structure parameters in the mixed operation mode are adjusted, the influence of the number of take-off and landing points n1 of the first ring layer, the total number of ring layers I, and the radius increment Δr on the unmanned aerial vehicle operation safety and flight efficiency is analyzed, so as to improve the operation safety of the flight procedure in the mixed operation mode and the unmanned aerial vehicle operation efficiency. The number of risk unmanned aerial vehicles under different parameter conditions is calculated to analyze the influence on the flight procedure operation safety; the average flight time of the unmanned aerial vehicle is calculated, and the number of unmanned aerial vehicles completing the flight task within 20s and 25s is counted, so as to evaluate the influence of the structure parameters on the unmanned aerial vehicle operation efficiency.

[0119] The details of the present application are known.

[0120] The above examples are only for illustrating the technical concept and characteristics of the present application, the purpose is to enable the person skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method for designing and evaluating flight procedures for urban vertical takeoff and landing airports, characterized in that: Includes the following steps: Step 1: Define the basic structure of the flight procedure for urban vertical take-off and landing airports, define the geometric layout and operational functions of take-off and landing points, and design flight procedure operation rules based on the hovering and waiting strategy of multi-rotor UAVs and the Floyd shortest path planning algorithm based on the dynamic right-of-way matrix of time step. In step one, the flight procedure for the urban vertical takeoff and landing airport includes clearly defined structural and geographical location information. This flight procedure is a nested three-dimensional structure, with a specified vertical interval d between each ring layer, where d ranges from 15 to 100 meters. Takeoff and landing points are located at specific positions within each ring layer. The number of takeoff and landing points in each ring layer is shown in the following formula: In the formula: i is the ring layer number, representing the i-th ring layer; n i The number of take-off and landing points in the i-th ring layer; To round up; The central angle between the two takeoff and landing points is calculated using the following formula: The take-off and landing points of the first ring layer are evenly distributed, and the angle between any two take-off and landing points is the same; the layout of the take-off and landing points of the i-th ring layer depends on the layout of the take-off and landing points of the (i-1)-th ring layer. When the number of take-off and landing points is the same, draw n lines with the center of the ring circle as the endpoint of the ray. i A ray, each passing through a starting and ending point on the (i-1)th ring layer; rotate the ray clockwise around the center of the ring layer by an angle of θ. n is set at the intersection of the ray and the i-th ring layer i One take-off and landing point; When the number of take-off and landing points of the two ring layers is different, draw the ray endpoints with the center of the circle as the endpoints respectively. Each ray passes through a starting and ending point on the (i-1)th ring layer. Rotating each ray clockwise around the center of the ring layer by an angle of θ. Set at the intersection of the ray and the i-th ring layer There are several take-off and landing points; with the center of the ring layer as the rotation center, each ray is then rotated clockwise by an angle of θ. i Set at the intersection of the ray and the i-th ring layer One take-off and landing point; To ensure that the first ring layer has enough space to accommodate a certain number of drones, the radius of the first ring layer is set to a specific value, and the radii of the remaining ring layers increase sequentially along a specific growth rate. Therefore, the formula for calculating the radius of each ring layer is as follows: In the formula: r i r1 is the radius of the i-th ring layer; r1 is the radius of the first ring layer; when Δr = 0, the flight procedure is a cylindrical structure, and when Δr > 0, the flight procedure is an inverted frustum-shaped structure that is wider at the top and narrower at the bottom; Step 2: Establish a mathematical model of the flight procedure based on three parameters: the take-off and landing point of the first ring layer, the total number of ring layers, and the radius growth. Determine the necessary parameters for other flight procedures and construct the optimal flight procedure structure. In step two, the mathematical model is constructed with the goals of maximizing flight procedure capacity and minimizing the theoretical range of the UAV within the flight procedure as indicators; the mathematical model is as follows: In the formula: l is the length of a single flight segment; d safe For the minimum safety interval; θ safe The minimum safe central angle; n1 is the number of take-off and landing points in the first ring layer; I is the total number of ring layers; Δr is the radius increase; z is the height difference between two ring layers; Step 3: Select flight procedure evaluation indicators, establish a flight procedure evaluation system, compare the safety and operational efficiency of flight procedures under different UAV traffic flow densities and operating modes, and select the flight procedure operating mode with better operational performance; Step 4: Analyze the impact of three parameters—the number of take-off and landing points in the first ring layer, the total number of ring layers, and the radius increase—on the flight procedure operation effect, and compare and analyze strategies to improve the efficiency of flight procedures in the mixed operation mode. Using UAV flow under a specific traffic flow density as an experiment, and using UAV flight data in the mixed operation mode, arrival operation mode, and departure operation mode as a control group, adjust the flight procedure structure parameters in the mixed operation mode, and analyze the impact of the number of take-off and landing points n1 in the first ring layer, the total number of ring layers I, and the radius increase Δr on UAV operation safety and flight efficiency, so as to improve the operation safety and UAV operation efficiency of the flight procedure in the mixed operation mode.

2. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 1, characterized in that: In step one, the flight procedure for the urban vertical take-off and landing airport includes take-off and landing points that undertake take-off and landing tasks. These points connect different ring layers and serve as transportation hubs for each ring layer. Multi-rotor UAVs can ascend or descend along fixed routes from the take-off and landing points to an adjacent ring layer, or they can fly over waypoints to move to other routes within the same ring layer. The flight procedure defines circular routes and transfer routes, and designs layout rules for the two types of routes respectively. The UAVs maintain a minimum safe separation during the flight procedure. During the flight program, the UAV completes either an approach flight or a departure flight. In the approach flight, the UAV enters from the take-off and landing point of the outermost ring layer and proceeds to a specific take-off and landing point of the first ring layer. In the departure flight, the UAV departs from the take-off and landing point of the first ring layer and proceeds to a specific take-off and landing point of the outermost ring layer. During the flight program, the UAV follows the flight program operation rules based on the Floyd shortest path planning algorithm with a dynamic path right matrix based on time steps.

3. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 2, characterized in that: The circular route is the route between two take-off and landing points in the current ring layer, and the UAV flies in circles along this route within the same ring layer; the transfer route is the route between two waypoints in different ring layers, and the UAV uses this type of route to transfer between ring layers.

4. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 2, characterized in that: Unmanned aerial vehicles (UAVs) have mixed operation modes, approach operation mode, and departure operation mode in their flight procedures. To ensure the safe operation of the flight procedure system, the hovering and waiting strategy for multi-rotor UAVs is as follows: (1) In the approach operation mode, the UAV leaves the low-altitude public airway and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure; (2) In the departure operation mode, the UAV takes off from the ground end of the city's vertical take-off and landing airport and flies to a public low-altitude air route; (3) In the mixed operation mode, the arrival drone and the departure drone fly at the same time; the arrival drone detaches from the low-altitude public airway and lands on the ground section of the urban vertical take-off and landing airport along the flight procedure; the departure drone takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude airway. (4) Within the circular flight path, the UAV flies in the same direction in a counterclockwise direction; (5) Within the transfer route, UAVs are only allowed to fly in one direction; in approach operation mode, UAVs climb along the route. In departure operation mode, the drone descends along its flight path; In the hybrid operation mode, the flight direction of the UAV must be clearly defined for each transfer route. The transfer routes for UAVs to climb and the transfer routes for UAVs to descend are arranged alternately between the two ring layers. In two adjacent transfer routes, one transfer route is for UAVs to climb and the other route is for UAVs to descend. (6) To ensure the safe operation of the flight procedure, the distance between the two UAVs must meet the minimum safe interval requirement during the flight procedure operation. (7) If the minimum safe distance is not met when the two UAVs enter the route from the take-off and landing point, the UAVs shall execute the flight waiting procedure: the latter is that the UAV farther from the take-off and landing point hovers in place and waits until the minimum safe distance between the two UAVs is restored. (8) If the UAV does not meet the minimum safe interval during flight, the UAV behind the flight path shall hover in place and wait until the minimum safe interval is met before it can continue to fly.

5. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 2, characterized in that: The Floyd shortest path planning algorithm based on the dynamic path weight matrix with time step is as follows: (1) Determine if a path exists from the take-off and landing point numbered i to the take-off and landing point numbered j, and denote the existing path as l. ij Add it to set L and calculate l. ij Path length c ij ; (2) Construct an N×N dynamic road weight matrix W Road The elements in the dynamic road weight matrix are calculated as follows: (3) Construct an N×N dynamic road weight matrix W Road The elements in the dynamic road weight matrix are calculated as follows: W Road [i,j]=w Road ×n UAV In the formula: W Road [i,j] represents the dynamic right-of-way for the route from the i-th take-off and landing point to the j-th take-off and landing point; w Road Weights for individual drones; n UAV This represents the number of drones on the flight path from the i-th take-off and landing point to the j-th take-off and landing point; The expression for the dynamic road weight matrix A is as follows: A[i,j]=G Road [i,j]+W Road [i,j] (4) When the UAV arrives at any take-off or landing point within the flight program, except for the termination take-off and landing point, update the dynamic path right matrix W based on the time step. Road The Floyd algorithm is used to calculate the remaining optimal flight segment of the UAV under the dynamic right-of-way matrix A.

6. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 1, characterized in that: In step three, in terms of safety, the waiting time of drones entering a waiting state due to being close to the minimum safe interval (i.e., an unsafe state) is used as an indicator. Drones that exceed the acceptable waiting time range are considered unsafe drones, and the flight procedure operation efficiency is evaluated based on the number of unsafe drones. In terms of operation efficiency, the flight time of drones in the flight procedure is used as an indicator. The larger the proportion of drones with short flight time, the higher the flight procedure operation efficiency.

7. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 6, characterized in that: The start-up intervals of the UAV's flight procedures follow an exponential distribution, as shown in the following expression: In the formula: λ is the number of drones arriving at the flight program per unit time; the larger λ is, the shorter the time interval between two drones and the denser the drone traffic flow. The flight program start time of each drone is obtained by superimposing the time intervals in sequence.

8. The method for designing and evaluating flight procedures for urban vertical takeoff and landing airports according to claim 1, characterized in that: In step four, using UAV flight data in mixed operation mode, arrival operation mode, and departure operation mode as a control group, the flight procedure structure parameters in mixed operation mode are adjusted. The impact of the number of take-off and landing points in the first ring layer, the total number of ring layers, and the radius increase on UAV operation safety and flight efficiency is analyzed to improve the operation safety and efficiency of the flight procedure in mixed operation mode. The number of risky UAVs under different parameter conditions is calculated to analyze their impact on the operation safety of the flight procedure. The average flight time of UAVs is calculated and the number of UAVs that complete flight tasks within a specific time period is counted to evaluate the impact of structural parameters on UAV operation efficiency.

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