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

Abstract

The invention discloses an urban vertical take-off and landing airport flight program design and evaluation method, which comprises the following steps of 1, determining an urban vertical take-off and landing airport flight program basic structure and an operation function, and designing a multi-rotor unmanned aerial vehicle in-situ hovering waiting strategy and a flight program operation rule of a dynamic road right matrix planning algorithm; 2, establishing a flight program mathematical model, determining necessary parameters of a flight program, and constructing an optimal flight program structure; 3, selecting a flight program evaluation index, determining a flight program evaluation system, and analyzing the safety and operation efficiency of the flight program; and 4, analyzing the influence of three parameters, namely the first annular layer take-off and landing point, the total number of annular layers and the radius increase amount, on the operation effect of the flight program. According to the flight program design and evaluation method for the vertical take-off and landing airport in the city, operation standardization of the unmanned aerial vehicles in the vertical take-off and landing airport in the city is standardized, operation safety is guaranteed, and operation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of flight program design and evaluation, and in particular to a flight program design and evaluation method for a city vertical take-off and landing airport based on an urban air traffic system. Background Art

[0002] With the rapid development of the low-altitude economy, the issue of take-off and landing routes for multi-rotor drones at urban vertical take-off and landing airports has gradually come into people's view. The flight procedures of urban vertical take-off and landing airports are part of the low-altitude routes, connecting the ground end of urban vertical take-off and landing airports and the public routes in low-altitude airspace. At present, there are few studies focusing on the impact of the specific structure and parameters of the circular flight program on the operation effect. Secondly, the simulation operation scenario of the multi-rotor drone flight program does not fully consider the operation effect of the flight program of the urban vertical take-off and landing airport in different operation scenarios. These will become problems that must be solved in the development of urban air traffic. Summary of the invention

[0003] The present invention aims to provide a method for designing and evaluating flight procedures for urban vertical take-off and landing airports, which can effectively solve the problems mentioned in the background questions and provide theoretical support for the optimization of subsequent practical application processes.

[0004] The technical solution of the present invention is as follows:

[0005] Step 1: Define the basic structure of the flight program of the urban vertical take-off and landing airport, clarify the geometric layout and operation functions of the take-off and landing points, and design the flight program operation rules based on the multi-rotor UAV in-situ hovering waiting strategy and the Floyd shortest path planning algorithm based on the dynamic road right matrix based on the time step.

[0006] Step 2: Establish a mathematical model of the flight program based on the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius growth, determine the necessary parameters of other flight programs, and construct the optimal flight program structure.

[0007] Step 3: Select flight procedure evaluation indicators, establish a flight procedure evaluation system, compare the safety and operating efficiency of flight procedures under different urban drone traffic flow densities and operating modes, and select the flight procedure operating mode with better operating performance.

[0008] Step 4: Analyze the impact of the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius growth on the operation effect of the flight program, and compare and analyze the strategies to improve the operation efficiency of the flight program in the mixed operation mode.

[0009] Furthermore, in step 1, the flight program of the urban vertical take-off and landing airport includes clear structural and geographical location information. The flight program is a three-dimensional structure of nested ring layers. The vertical spacing distance d is specified between each ring layer, and the value range of d is 15-100m; the number of take-off and landing points in each ring layer is shown in the following formula:

[0010]

[0011] Where: i is the ring layer number, indicating the i-th ring layer; n i is the number of take-off and landing points in the i-th ring layer; To round up;

[0012] The central angle between two take-off and landing points is calculated as follows:

[0013]

[0014] The take-off and landing points of the first ring layer are evenly distributed, and the angles between the two take-off and landing points are 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-1th ring layer;

[0015] When the number of take-off and landing points is the same, draw n i rays, each ray passes through a take-off and landing point on the i-1th ring layer; with the center of the ring layer as the rotation center, the ray is rotated clockwise, and the rotation angle is Set n at the intersection of the ray and the i-th ring layer i take-off and landing points;

[0016] When the number of take-off and landing points of the two ring layers is different, draw the rays, each ray passes through a take-off and landing point on the i-1th ring layer, and each ray is rotated clockwise with the center of the ring layer as the rotation center. The rotation angle is Set at the intersection of the ray and the i-th ring layer Take off and land at points; take the center of the ring as the rotation center, and then rotate each ray clockwise, the rotation angle is θ i , set at the intersection of the ray and the i-th ring layer take-off and landing points;

[0017] In order 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 radius of the remaining ring layers increases in sequence along a specific growth amount. The radius calculation formula of each ring layer is as follows:

[0018]

[0019] Where: r iis the radius of the i-th ring layer; r1 is the radius of the first ring layer; when Δr=0, the flight program is a cylindrical structure, and when Δr>0, the flight program is an inverted frustum-shaped structure that is wide at the top and narrow at the bottom.

[0020] Furthermore, in step one, the flight procedure of the urban vertical take-off and landing airport includes a take-off and landing point for taking off and landing tasks. The take-off and landing point connects different ring layers and is the transportation hub of each ring layer. The multi-rotor UAV can ascend or descend along a fixed route at the take-off and landing point to another adjacent ring layer, and can also fly over the route point to move to other routes in the same ring layer; the circular route and the transfer route are defined in the flight procedure, and the layout rules of the two types of routes are designed respectively; the UAV maintains a minimum safety interval in the flight procedure; the UAV completes an approach flight mission or a departure flight mission in the flight procedure. In the approach flight mission, the UAV enters from the take-off and landing point of the outermost ring layer to the specific take-off and landing point of the first ring layer; in the departure flight mission, the UAV departs from the take-off and landing point of the first ring layer to the specific take-off and landing point of the outermost ring layer; the UAV follows the flight program operation rules of the Floyd shortest path planning algorithm based on the dynamic road right matrix based on the time step in the middle of the flight program.

[0021] Furthermore, the circular route is a route between two take-off and landing points in the current ring layer, and the UAV flies in circles along this route in the same ring layer; the transfer route is a route between two waypoints in different ring layers, and the UAV realizes the transfer of ring layers through this type of route.

[0022] Furthermore, the UAV has a mixed operation mode, an approach operation mode, and a departure operation mode in the flight program. To ensure the safe operation of the flight program system, the multi-rotor UAV hovering waiting strategy is as follows:

[0023] (1) In the approach operation mode, the UAV detaches from the low-altitude public route and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure;

[0024] (2) In the departure operation mode, the UAV 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 approaching drone and the departing drone fly simultaneously; the approaching drone detaches from the low-altitude public route and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure; the departing drone takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude route;

[0026] (4) Within the loop route, the UAV flies in the same direction in a counterclockwise direction;

[0027] (5) UAVs are only allowed to fly in a single direction within the transfer route; in the approach operation mode, UAVs climb along the route; in the departure operation mode, UAVs descend along the route; in the mixed operation mode, the single transfer route must clearly specify the flight direction of the UAV, and the transfer routes for UAVs to climb and the transfer routes for UAVs to descend between the two ring layers are arranged alternately in sequence. Among the two adjacent transfer routes, one transfer route is for UAVs to climb, and the other route is for UAVs to descend;

[0028] (6) To ensure the safe operation of the flight program, the distance between the two drones must meet the minimum safety interval requirements during the flight program operation;

[0029] (7) If the two drones do not meet the minimum safety interval when entering the route from the take-off and landing point, the drones will execute the flight waiting procedure: the latter means that the drone farther away from the take-off and landing point will hover and wait until the minimum safety interval between the two drones is restored;

[0030] (8) If the UAV does not meet the minimum safety interval during flight, the UAV behind the flight program will hover in place and wait until the minimum safety interval is met before continuing to fly.

[0031] Furthermore, the Floyd shortest path planning algorithm based on the dynamic road right matrix of the time step has the following specific steps:

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

[0033] (2) Constructing an N×N dynamic road weight matrix W Road , the calculation method of the elements in the dynamic road right matrix is ​​as follows

[0034]

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

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

[0037] Where: W Road [i,j] is the dynamic right of way 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 drone; n UAV is the number of drones 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 road right matrix A is as follows:

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

[0040] (4) When the UAV arrives at any take-off and landing point in the flight program except the termination take-off and landing point, the dynamic road right matrix W is updated based on the time step Road , the Floyd algorithm is used to calculate the remaining optimal flight segments of the UAV under the dynamic road right matrix A.

[0041] Furthermore, in step 2, the construction of the mathematical model is based on maximizing the flight program capacity and minimizing the theoretical range of the drone in the flight program; the mathematical model is as follows:

[0042]

[0043] Where: l is the length of a single route; d safe is the minimum safety interval; θ safe is the minimum safe center 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 growth.

[0044] Furthermore, in step three, the safety aspect is measured by the waiting time of the drone entering a waiting state due to being on the verge of the minimum safety interval, i.e., an unsafe state. Drones that exceed the acceptable waiting time range are unsafe drones, and the efficiency of the flight program is evaluated based on the number of unsafe drones. The operating efficiency is measured by the flight time of the drone in the flight program. The greater the proportion of drones with short flight time, the higher the operating efficiency of the flight program.

[0045] Furthermore, the start time interval of the UAV executing the flight program follows an exponential distribution, which is expressed as follows:

[0046]

[0047] Where λ is the number of UAVs that arrive at the flight program per unit time. The larger the λ is, the shorter the time interval between two UAVs is and the denser the UAV traffic flow is. The time intervals are superimposed in sequence to obtain the flight program start time of each UAV. The operation data of the UAVs are calculated under the parameters λ=0.5, 0.75, 1, and 1.25 respectively.

[0048] Furthermore, in step 4, the flight data of UAVs in the hybrid operation mode, approach operation mode, and departure operation mode are used as the control group, the flight program structural parameters in the hybrid operation mode are adjusted, and 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 growth on the UAV operation safety and flight efficiency are analyzed to improve the operation safety of the flight program and the operation efficiency of the UAV in the hybrid operation mode; the number of risky UAVs under different parameter conditions is calculated to analyze its impact on the operation safety of the flight program; the average flight time of the UAV is calculated and the number of UAVs that complete the flight mission within a specific time is counted to evaluate the impact of structural parameters on the operation efficiency of the UAV.

[0049] The beneficial effects of the present invention are as follows: the present invention adopts a flight procedure design and evaluation method for an urban vertical take-off and landing airport, which solves the related problems mentioned in the background technology, while realizing the safety guarantee problem of UAV entry and departure operations, and improving the operation efficiency, laying a solid foundation for the subsequent construction of urban vertical take-off and landing airports. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flowchart of an embodiment of a method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport.

[0051] Figure 2 A schematic diagram of the structural design of a flight program for an urban vertical take-off and landing airport according to an embodiment of a method for designing and evaluating a flight program for an urban vertical take-off and landing airport according to the present invention.

[0052] Figure 3 This is a schematic diagram of a two-ring layout of an embodiment of a method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to the present invention, wherein the left figure is a schematic diagram of a two-ring layout when the number of take-off and landing points on the two ring layers is the same, and the right figure is a schematic diagram of a two-ring layout when the number of take-off and landing points on the two ring layers is different.

[0053] Figure 4 This is a schematic diagram of the transfer route layout of an embodiment of a method for designing and evaluating flight procedures for an urban vertical take-off and landing airport in the present invention, wherein the left figure is a schematic diagram of the transfer route layout between two ring layers when the number of take-off and landing points on the two ring layers is different, and the right figure is a schematic diagram of the transfer route layout between two ring layers when the number of take-off and landing points on the two ring layers is the same.

[0054] Figure 5 This is a NSGA-II optimization effect diagram of an embodiment of a method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to the present invention.

[0055] Figure 6 A hybrid operation mode flight program structure of an embodiment of a method for designing and evaluating a flight program for an urban vertical take-off and landing airport according to the present invention.

[0056] Figure 7The present invention discloses an approach operation mode flight program structure of an embodiment of a method for designing and evaluating a flight program for an urban vertical take-off and landing airport.

[0057] Figure 8 The present invention discloses a flight program structure for a departure operation mode in an embodiment of a method for designing and evaluating a flight program for an urban vertical take-off and landing airport. DETAILED DESCRIPTION

[0058] This section further illustrates the technical solution of the present invention through drawings and embodiments.

[0059] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0060] Example

[0061] The present invention provides a method for designing and evaluating flight procedures for a city vertical take-off and landing airport, such as Figure 1 As shown, the following steps are included:

[0062] Step 1: Define the basic structure of the flight program of the urban vertical take-off and landing airport, clarify the geometric layout and operation functions of the take-off and landing points, and design the flight program operation rules based on the multi-rotor drone in-situ hovering waiting strategy and the Floyd shortest path planning algorithm based on the dynamic road right matrix based on the time step. In terms of flight program structure design, this example takes the clear airspace of 200m*200m*100m as an example, and takes the light unmanned aerial vehicle in the "Interim Regulations on the Flight Management of Unmanned Aerial Vehicles" as the research object. The clear airspace of the urban vertical take-off and landing airport is equipped with the necessary communication, navigation, and monitoring equipment for the operation of unmanned aerial vehicles. Figure 2The diagram of the flight program structure of the urban vertical take-off and landing airport with three ring layers is shown in the figure. From the inside to the outside, they are defined as the first ring layer, the second ring layer, and the third ring layer respectively; the first ring layer is 15m away from the ground end, and the height difference between each ring layer is 15m. There are take-off and landing points at specific locations in each ring layer. The take-off and landing points connect different ring layers and are the transportation hubs of each ring layer. Multi-rotor drones can rise or descend along fixed routes at the take-off and landing points to another adjacent ring layer, or they can fly over waypoints and move to other routes in the same ring layer. In the flight program, drones perform two types of flight missions: approach flight missions and departure flight missions; in the approach flight mission, the drone enters from the take-off and landing points of the outermost ring layer to the specific take-off and landing points of the first ring layer; in the departure flight mission, the drone departs from the take-off and landing points of the first ring layer to the specific take-off and landing points of the outermost ring layer. The take-off and landing points of the outermost ring layer connect the flight program with the low-altitude route network. The approaching drone is released from the low-altitude route network and flies freely to the nearest take-off and landing point of the flight program; the departing drone flies out from the take-off and landing points of the outermost ring layer of the flight program and flies freely to the initial waypoint of the low-altitude route network. The take-off and landing points of the first ring layer undertake the take-off and landing tasks. The departing drone takes off vertically from the ground parking position to the first ring layer take-off and landing point to enter the flight program of the urban vertical take-off and landing airport. After the approaching drone completes the flight mission from the urban vertical take-off and landing airport flight program, it lands vertically at the first ring layer take-off and landing point to the ground end parking position.

[0063] The number of take-off and landing points in each ring layer is as follows:

[0064]

[0065] Where: i is the ring layer number, indicating the i-th ring layer; n i is the number of take-off and landing points in the i-th ring layer; To round up.

[0066] The formula for calculating the central angle between two take-off and landing points is as follows:

[0067]

[0068] The take-off and landing points of the first ring layer are evenly distributed, and the angles between the two take-off and landing points are 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-1th ring layer. Figure 3 The following are the schematic diagrams of the ring layout when the number of take-off and landing points of the two ring layers is the same and different. When the number of take-off and landing points is the same, n lines with the center of the ring layer as the endpoint of the ray are drawn respectively. i rays, each ray passes through a take-off and landing point on the i-1th ring layer; with the center of the ring layer as the rotation center, the ray is rotated clockwise, and the rotation angle is Set n at the intersection of the ray and the i-th ring layer i When the number of take-off and landing points of the two ring layers is different, draw the rays, each ray passes through a take-off and landing point on the i-1th ring layer, and each ray is rotated clockwise with the center of the ring layer as the rotation center. The rotation angle is Set at the intersection of the ray and the i-th ring layer Take off and land at points; take the center of the ring as the rotation center, and then rotate each ray clockwise, the rotation angle is θ i , set at the intersection of the ray and the i-th ring layer A take-off and landing point.

[0069] Based on the layout of take-off and landing points in the flight program, the routes in the flight program of the urban vertical take-off and landing airport are divided into two categories. One is the route between two take-off and landing points in the current ring layer. The drone flies along this route in the same ring layer, and this route is called a circular route; the other is the route between two waypoints in different ring layers. The drone realizes the transfer of the ring layer through this type of route, and this type of route is called a transfer route.

[0070] In order to ensure that the first ring layer has enough space to accommodate a certain number of drones, the present invention sets the radius of the first ring layer to a specific value, and the radii of the remaining ring layers increase in sequence along a specific growth amount. Therefore, the radius calculation formula of each ring layer is as follows:

[0071]

[0072] Where: r i is the radius of the ith ring layer; r1 is the radius of the first ring layer. When Δr=0, the flight program is a cylindrical structure, and when Δr>0, the flight program is an inverted truncated cone structure that is wide at the top and narrow at the bottom.

[0073] In terms of flight program rules, based on the multi-ring structure of the flight program and the flight characteristics of multi-rotor UAVs, the present invention designs three flight program operation modes, namely: mixed operation mode, approach operation mode, and departure operation mode. Figure 6-8 In order to ensure the safe operation of the flight procedure system, the flight procedure operation rules are clarified as follows:

[0074] (1) In the approach operation mode, the UAV detaches from the low-altitude public route and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure.

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

[0076] (3) In the mixed operation mode, the approaching drone and the departing drone fly simultaneously. The approaching drone detaches from the low-altitude public route and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure; the departing drone takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude route.

[0077] (4) Within the loop route, the UAVs fly in the same direction in a counterclockwise direction.

[0078] (5) UAVs are only allowed to fly in a single direction within the transfer route. In the approach operation mode, the UAV climbs along the route; in the departure operation mode, the UAV descends along the route; in the mixed operation mode, the single transfer route must clearly specify the UAV's flight direction. The transfer routes for the UAV to climb and the transfer routes for the UAV to descend are arranged alternately between the two ring layers. Among the two adjacent transfer routes, one transfer route is for the UAV to climb, and the other route is for the UAV to descend. Figure 4 This is a schematic diagram of the transfer route layout when the number of take-off and landing points on the two ring layers is different and a schematic diagram of the transfer route layout when the number of take-off and landing points on the two ring layers is the same.

[0079] (6) To ensure the safe operation of the flight program, the distance between the two drones must meet the minimum safety interval requirements during the flight program.

[0080] (7) If the two drones do not meet the minimum safety interval when entering the route from the take-off and landing point, the drones will execute the flight waiting procedure: the latter is that the drone farther away from the take-off and landing point will hover and wait until the minimum safety interval between the two drones is restored.

[0081] (8) If the UAV does not meet the minimum safety interval during flight, the UAV behind the flight program will hover in place and wait until the minimum safety interval is met before continuing to fly.

[0082] In terms of the UAV route planning algorithm, both the approach mission and the departure mission can be regarded as the shortest path problem from the initial take-off and landing point to the final take-off and landing point. This paper selects the Floyd algorithm to solve the shortest path problem. The Floyd algorithm uses the idea of ​​dynamic programming to traverse all nodes in the network and find the shortest path between two points. Therefore, compared with other algorithms, the Floyd algorithm can solve the shortest path problem of directed graphs and network graphs with negative road rights. In order to make full use of the advantages of the flight program structure and avoid local congestion of the flight program, this paper designs a Floyd shortest path planning algorithm based on a dynamic road right matrix based on the time step. The algorithm steps are as follows:

[0083] (1) Determine whether a path from point numbered to point numbered j exists, and denote the existing path as l ij , add it to the set L, and calculate l ij The path length c ij .

[0084] (2) Constructing an N×N dynamic road weight matrix W Road , the calculation method of the elements in the dynamic road right matrix is ​​as follows:

[0085]

[0086] (3) Constructing an N×N dynamic road weight matrix W Road , the calculation method of the elements in the dynamic road right matrix is ​​as follows:

[0087] W Road [i,j]=w Road ×n UAV

[0088] Where: W Road [i,j] is the dynamic right of way 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 drone; n UAV is the number of drones on the route from the i-th take-off and landing point to the j-th take-off and landing point.

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

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

[0091] (4) When the UAV arrives at any take-off and landing point in the flight program except the termination take-off and landing point, the dynamic road right matrix W is updated based on the time step Road , the Floyd algorithm is used to calculate the remaining optimal flight segments of the UAV under the dynamic road right matrix A.

[0092] On the basis of the traditional Floyd algorithm, the time required for the change of the UAV's flight state is used as the time step, and dynamic road rights are added to calculate the shortest path of the UAV during the overall process of performing the flight mission. This allows the UAV to avoid possible congested segments and choose routes with similar ranges and fewer UAVs to execute the flight program, thereby making full use of the multi-ring structure of the flight program system to improve the safety of flight program operation and the flight efficiency of UAVs. If the Floyd algorithm based on the dynamic road right matrix cannot calculate a feasible solution for a certain UAV, that is, the capacity of all traversable segments is saturated, then the flight program of this configuration is considered to be overloaded and needs to be replaced.

[0093] Step 2: Establish a mathematical model of the flight program based on the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius growth, determine the necessary parameters of other flight programs, and build the optimal flight program structure. This example takes Phantom4 as an example, and the safety interval is 5m. The radius of the first ring layer is 20m, and the length of the circular route is l i , the calculation formula is as follows:

[0094]

[0095] The transfer route length l from take-off point i to take-off point i-1 i,i-1 , the calculation formula is as follows:

[0096]

[0097] Where: r i 、r i-1 is the ring layer 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 procedure capacity, in this flight procedure, the capacity of a single route is as follows:

[0099]

[0100] Where: c road is the maximum capacity of the route; l is the length of the route; d safe is the minimum safe interval; Indicates rounding down.

[0101] Based on the minimum safety interval between the two drones and the ring radius, the minimum safety center angle between the two drones can be obtained, that is, the minimum angle of the arc formed by the two drones and the center of the ring under an acceptable safety level. The calculation formula is as follows:

[0102]

[0103] Where: θ safe is the minimum safe center angle.

[0104] Therefore, the capacity of a single loop route in the flight procedure system is C circuit The calculation formula can be expressed as:

[0105]

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

[0107]

[0108] To ensure the capacity of the first ring layer circulation route, n1 should not be too large, and the upper limit of n1 is set to 8; to ensure the scheduling performance of the first ring layer, the lower limit of the first ring layer take-off and landing points is set to 2. The present invention determines the value range of the radius growth amount Δr based on the extreme value of the theoretical maximum ring layer, that is, the sixth ring layer.

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

[0110]

[0111] The relevant parameter values ​​are shown in the following table:

[0112]

[0113] The Pareto frontier is obtained based on the NSGA-II algorithm. Figure 5 shown.

[0114] Step 3: Select flight program evaluation indicators, establish a flight program evaluation system, compare the safety and operating efficiency of flight programs under different urban drone traffic flow densities and operating modes, and select flight program operating modes with better operating performance. The present invention evaluates flight programs from two dimensions: system safety and operating efficiency. The present invention uses the number of risky drones as an indicator to evaluate the system safety of flight programs. Although when a drone is close to the minimum safety interval, it is in an unsafe state and the collision probability reaches the maximum value under an acceptable degree, based on factors such as the overall operating time, the nature of the drone flight mission, and the actual operation of urban air traffic, the present invention assumes that the total waiting time during the operation of the drone for the Phantom 4 model does not exceed 1s, which is within the acceptable range of actual operating safety, otherwise it is regarded as a risky drone. The length of the waiting time reflects the degree of safety risk during the flight of the drone. When the distance between drones is equal to the minimum safety interval, the drone needs to execute the waiting program; when the distance between drones is equal to the minimum safety interval, the probability of collision and other dangers is close to the boundary of the acceptable range; the longer the waiting time during the flight of the drone, that is, the longer the drone is at the boundary of the acceptable safety range during operation, the higher the safety risk of the drone operation.

[0115] The flight time of the drone is selected as an indicator to characterize the efficiency of the flight program. The calculation formula for the flight time of the drone is as follows:

[0116]

[0117] The longer the drone's flight time, the lower the efficiency of the flight program. Based on the shortest flight time of the drone in the flight program, an acceptable delay time is set, and the proportion of drones within the acceptable delay time in actual operation is counted to compare and analyze the efficiency of the flight program.

[0118] Step 4: Analyze the impact of the three parameters of the first ring layer take-off and landing points, the total number of ring layers, and the radius growth on the operation effect of the flight program, and compare and analyze the strategies to improve the efficiency of the flight program in the mixed operation mode. Take the drone flow under a specific traffic flow density as the experiment, and the drone flight data in the mixed operation mode, approach operation mode, and departure operation mode as the control group. Adjust the structural parameters of the flight program in the mixed operation mode, and analyze the impact of the number of take-off and landing points n1, the total number of ring layers I, and the radius growth Δr of the first ring layer on the safety and flight efficiency of the drone operation, so as to improve the safety of the flight program and the efficiency of the drone operation in the mixed operation mode. Calculate the number of risk drones under different parameter conditions to analyze their impact on the safety of the flight program operation; calculate the average flight time of the drone and count the number of drones that complete the flight mission within 20s and 25s, and evaluate the impact of structural parameters on the efficiency of the drone operation.

[0119] Matters not covered by the present invention are known technologies.

[0120] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing and evaluating flight procedures for an urban vertical take-off and landing airport, characterized in that: The following steps are involved: Step 1: Define the basic structure of the flight program of the urban vertical take-off and landing airport, clarify the geometric layout and operation functions of the take-off and landing points, and design the flight program operation rules based on the multi-rotor drone in-situ hovering waiting strategy and the Floyd shortest path planning algorithm based on the dynamic road right matrix of the time step; Step 2: Establish a mathematical model of the flight program based on the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius growth, determine the necessary parameters of other flight programs, and construct the optimal flight program structure; Step 3: Select flight procedure evaluation indicators, establish a flight procedure evaluation system, compare the safety and efficiency of flight procedures under different urban drone traffic density and operation modes, and select the flight procedure operation mode with better operation performance; Step 4: Analyze the impact of the three parameters of the first ring layer take-off and landing point, the total number of ring layers, and the radius growth on the operation effect of the flight program, and compare and analyze the strategies to improve the operation efficiency of the flight program in the mixed operation mode.

2. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 1, characterized in that: In step 1, the flight program of the urban vertical take-off and landing airport includes clear structural and geographical location information. The flight program is a three-dimensional structure of nested ring layers. The vertical spacing distance d is specified between each ring layer, and the value range of d is 15-100m; a take-off and landing point is set at a specific position in each ring layer; the number of take-off and landing points in each ring layer is shown in the following formula: Where: i is the ring layer number, indicating the i-th ring layer; n i is the number of take-off and landing points in the i-th ring layer; To round up; The central angle between two take-off and landing points is calculated as follows: The take-off and landing points of the first ring layer are evenly distributed, and the angles between the two take-off and landing points are 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-1th ring layer; When the number of take-off and landing points is the same, draw n i rays, each ray passes through a take-off and landing point on the i-1th ring layer; with the center of the ring layer as the rotation center, the ray is rotated clockwise, and the rotation angle is Set n at the intersection of the ray and the i-th ring layer i take-off and landing points; When the number of take-off and landing points of the two ring layers is different, draw the rays, each ray passes through a take-off and landing point on the i-1th ring layer, and each ray is rotated clockwise with the center of the ring layer as the rotation center. The rotation angle is Set at the intersection of the ray and the i-th ring layer Take off and land at points; take the center of the ring as the rotation center, and then rotate each ray clockwise, the rotation angle is θ i , set at the intersection of the ray and the i-th ring layer take-off and landing points; In order 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 radius of the remaining ring layers increases in sequence along a specific growth amount. The radius calculation formula of each ring layer is as follows: Where: r i is the radius of the i-th ring layer; r1 is the radius of the first ring layer; when Δr=0, the flight program is a cylindrical structure, and when Δr>0, the flight program is an inverted frustum-shaped structure that is wide at the top and narrow at the bottom.

3. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 2, characterized in that: In step 1, the flight procedure of the urban vertical take-off and landing airport includes a take-off and landing point for take-off and landing tasks. The take-off and landing point connects different ring layers and is a traffic hub for each ring layer. The multi-rotor drone can rise or descend along a fixed route at the take-off and landing point to another adjacent ring layer, and can also fly over the waypoint to move to other routes in the same ring layer; the flight procedure defines a circular route and a transfer route, and the layout rules of the two types of routes are designed respectively; the drone maintains a minimum safety interval in the flight procedure; The UAV completes an approach flight mission or a departure flight mission in the flight program. In the approach flight mission, the UAV enters from the take-off and landing point of the outermost ring layer and arrives at the specific take-off and landing point of the first ring layer; in the departure flight mission, the UAV departs from the take-off and landing point of the first ring layer and arrives at the specific take-off and landing point of the outermost ring layer; in the middle of the flight program, the UAV follows the flight program operation rules of the Floyd shortest path planning algorithm based on the dynamic road right matrix based on the time step.

4. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 3, 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 a circle along this route in the same ring layer; the transfer route is the route between two waypoints in different ring layers, and the UAV realizes the transfer of ring layers through this type of route.

5. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 3, characterized in that: The UAV has mixed operation mode, approach operation mode, and departure operation mode in the flight program. To ensure the safe operation of the flight program system, the multi-rotor UAV hovering waiting strategy is as follows: (1) In the approach operation mode, the UAV detaches from the low-altitude public route 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 urban vertical take-off and landing airport and flies to a public low-altitude route; (3) In the mixed operation mode, the approaching drone and the departing drone fly simultaneously; the approaching drone detaches from the low-altitude public route and lands on the ground section of the urban vertical take-off and landing airport according to the flight procedure; the departing drone takes off from the ground end of the urban vertical take-off and landing airport and flies to the public low-altitude route; (4) Within the loop route, the UAV flies in the same direction in a counterclockwise direction; (5) UAVs are only allowed to fly in a single direction within the transfer route; UAVs are allowed to climb along the route in approach operation mode; In the departure operation mode, the UAV descends along the route; In the mixed operation mode, a single transfer route needs to specify the flight direction of the drone. The transfer routes for the drone to climb and the transfer routes for the drone to descend are arranged alternately between the two ring layers. Among the two adjacent transfer routes, one transfer route is for the drone to climb, and the other route is for the drone to descend. (6) To ensure the safe operation of the flight program, the distance between the two drones must meet the minimum safety interval requirements during the flight program operation; (7) If the two drones do not meet the minimum safety interval when entering the route from the take-off and landing point, the drones will execute the flight waiting procedure: the latter means that the drone farther away from the take-off and landing point will hover and wait until the minimum safety interval between the two drones is restored; (8) If the UAV does not meet the minimum safety interval during flight, the UAV behind the flight program will hover in place and wait until the minimum safety interval is met before continuing to fly.

6. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 3, characterized in that: The Floyd shortest path planning algorithm based on the dynamic road right matrix of the time step has the following specific steps: (1) Determine whether there is a path from the take-off and landing point numbered i to the take-off and landing point numbered j. The existing path is recorded as l ij , add it to the set L, and calculate l ij The path length c ij ; (2) Constructing an N×N dynamic road weight matrix W Road , the calculation method of the elements in the dynamic road right matrix is ​​as follows Down: (3) Constructing an N×N dynamic road weight matrix W Road , the calculation method of the elements in the dynamic road right matrix is ​​as follows: A[i,j]=G Road [i,j]+W Road [i,j] Where: W Road [i,j] is the dynamic right of way 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 drone; n UAV is the number of drones on the route from the i-th take-off and landing point to the j-th take-off and landing point; The expression of the dynamic road right 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 and landing point in the flight program except the termination take-off and landing point, the dynamic road right matrix W is updated based on the time step Road , the Floyd algorithm is used to calculate the remaining optimal flight segments of the UAV under the dynamic road right matrix A.

7. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 6, characterized in that: In step 2, the construction of the mathematical model is based on maximizing the flight program capacity and minimizing the theoretical range of the drone in the flight program; the mathematical model is as follows: Where: l is the length of a single route; d safe is the minimum safety interval; θ safe is the minimum safe center 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 growth.

8. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 1, characterized in that: In step three, the safety factor is the waiting time when the drone enters the waiting state due to being close to the minimum safety interval, i.e. the unsafe state. The drones that exceed the acceptable waiting time range are unsafe drones, and the efficiency of the flight program is evaluated based on the number of unsafe drones. The operating efficiency is evaluated based on the flight time of the drone in the flight program. The greater the proportion of drones with short flight time, the higher the efficiency of the flight program.

9. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 8, characterized in that: The start time interval of the drone executing the flight program follows an exponential distribution, which is expressed as follows: Where: λ is the number of UAVs that arrive at the flight program per unit time; the larger the λ is, the shorter the time interval between two UAVs is, and the denser the UAV traffic flow is. The time intervals are superimposed in sequence to obtain the flight program start time of each UAV.

10. The method for designing and evaluating a flight procedure for an urban vertical take-off and landing airport according to claim 1, characterized in that: In step 4, the flight data of UAVs in the hybrid operation mode, approach operation mode, and departure operation mode are used as the control group, and the flight program structural parameters in the hybrid operation mode are adjusted to analyze 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 growth on the operation safety and flight efficiency of the UAV, so as to improve the operation safety of the flight program and the operation efficiency of the UAV in the hybrid operation mode; the number of risky UAVs under different parameter conditions is calculated to analyze its impact on the operation safety of the flight program; the average flight time of the UAV is calculated and the number of UAVs that complete the flight mission within a specific time is counted to evaluate the impact of structural parameters on the operation efficiency of the UAV.

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