Air route changing method of low-altitude aircraft

Abstract

The invention belongs to the field of low-altitude traffic, and particularly relates to an air route changing method of a low-altitude aircraft. The method is based on an air route model constructed by a trunk line air route network and a branch line air route network; the trunk route network adopts a layered three-dimensional route structure; the branch air route network is composed of a reversing function sub-network and a navigational speed transition function sub-network; after the low-altitude aircraft obtains a course adjustment instruction, the low-altitude aircraft enters a reversing function airway in the reversing function sub-network to climb, descend and steer, so that the low-altitude aircraft completes course change; and after the low-altitude aircraft obtains a navigational speed transition instruction, the low-altitude aircraft enters a navigational speed transition function route in the navigational speed transition function sub-network, and navigational speed change is carried out among layers of the layered three-dimensional route structure. According to the method, the large-scale unmanned aerial vehicle can have relatively high adaptability when facing task change or flight state adjustment in the high-speed running process in the three-dimensional layered air route.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of low-altitude traffic, and particularly relates to a method for changing a flight path of a low-altitude aircraft. BACKGROUND

[0002] With the large-scale application of urban air mobility (UAM) and logistics drones, the operation density of drones in low-altitude airspace is exponentially increasing. In the face of large-scale heterogeneous aircraft operation in a complex urban low-altitude environment, the current autonomous obstacle avoidance technology, airspace resource allocation, and automatic control technology of drones have defects, and the normal and safe operation of large-scale aircraft is a major problem that needs to be studied. The low-altitude public flight path can constrain the flight direction and path of a large number of aircraft, so that the aircraft can operate in an orderly manner within the specified flight path. Therefore, the scientific layout of the flight path network and the construction of the public flight path are particularly important. For the real-time change of tasks in the process of large-scale aircraft operation, the proposed model has high value and significance for maintaining the high-speed and safe operation of large-scale aircraft in the flight path.

[0003] In terms of the construction of the flight path network and the low-altitude flight path in the low-altitude traffic scenario, the current related research is relatively lacking. The traditional flight path change occupies a large airspace and takes a long time. In addition, the traditional drone flight lacks a speed transition mechanism, which makes the overall operation efficiency of the drone low and difficult to meet the demand for safe operation of high-density and high-speed drones in the low-altitude traffic scenario. SUMMARY

[0004] In order to solve the existing problems mentioned in the background, the application provides a method for changing a flight path of a low-altitude aircraft.

[0005] The method for changing a flight path of a low-altitude aircraft provided by the application comprises the following steps:

[0006] a flight path model constructed based on a trunk flight path network and a branch flight path network;

[0007] The trunk flight path network adopts a hierarchical three-dimensional flight path structure, and the branch flight path network adopts a reversing function subnetwork and a flight speed transition function subnetwork.

[0008] The flight path change method comprises flight direction adjustment and flight speed transition.

[0009] When the low-altitude aircraft receives a flight direction adjustment instruction, the low-altitude aircraft enters a reversing function flight path in the reversing function subnetwork to climb, descend, and turn, so that the low-altitude aircraft completes the flight direction change.

[0010] When the low-altitude aircraft receives a flight speed transition instruction, the low-altitude aircraft enters a flight speed transition function flight path in the flight speed transition function subnetwork to change the flight speed between the layers of the hierarchical three-dimensional flight path structure.

[0011] The low-altitude aircraft route change method adopts a spiral structure route for the reversing function route; the included angle between the tangent of the spiral curve and the trunk route axis in the trunk route network is 30°≤α≤60°, and the spiral radius is adjusted according to the change of the height layer, and the expression formula is as follows:

[0012] ΔR=K·h

[0013] Wherein, the value of K is determined by the speed and the surrounding environment of the route;

[0014] The low-altitude aircraft route change method adopts a spiral structure route for the speed transition function route, the included angle between the tangent of the spiral curve and the trunk route axis in the trunk route network is 30°≤α≤60°, and the spiral radius is adjusted according to the change of the speed, and the expression formula is as follows:

[0015] ΔR=λ·ΔV / V0

[0016] Wherein, λ is an acceleration coefficient;

[0017] The speed reference value of each layer in the layered three-dimensional route structure is V0+ΔV, and the heading constraint is θ+Δθ.

[0018] The low-altitude aircraft route change method adopts a spiral structure or a spiral structure of the speed transition route sub-network for the spiral structure route of the reversing function sub-network or the spiral structure of the speed transition route sub-network.

[0019] The low-altitude aircraft route change method sets an acceleration preparation area, a spiral acceleration area and a buffer area for the low-altitude aircraft in the trunk route network structure, and sets a horizontal safety interval and a vertical safety interval between the low-altitude aircrafts flying in the acceleration preparation area, the spiral acceleration area and the buffer area.

[0020] The low-altitude aircraft route change method sets a horizontal safety interval D h The expression formula is as follows:

[0021]

[0022] t is the response time of the aircraft, a b is the maximum braking acceleration, Δ S is the positioning error tolerance, γ is the safety factor, and the value is 1.2-1.6; v is the speed of the aircraft;

[0023] The vertical safety interval D v The formula is:

[0024]

[0025] Wherein, h min is the minimum safety interval, ρ is the air density, v z is the maximum climb rate, and η is the turbulence compensation coefficient.

[0026] The low-altitude aircraft route change method, the trunk route network comprises a low-speed route, a reverse route and a high-speed route;

[0027] The low-speed route, the reverse route and the high-speed route are each composed of a plurality of parallel same-direction routes;

[0028] The number of routes in a layer can be adjusted in real time according to route dynamic capacity evaluation, wherein the theoretical capacity evaluation of a single-layer route can be performed according to the formula:

[0029]

[0030] Wherein, C L is the capacity of a single-layer route, N L is the number of parallel routes for evaluation, V ave is a speed reference value, L u is the equivalent length of the aircraft, g is the acceleration of gravity, and D h is the horizontal safety interval.

[0031] The low-altitude aircraft route change method, the preparation area is the original route section area before real-time change of the low-altitude aircraft;

[0032] The spiral acceleration area is a spiral route for the low-altitude aircraft to implement speed transition when leaving the original route;

[0033] The buffer area is a speed buffer area for the low-altitude aircraft to merge into a new route;

[0034] The preparation area, the spiral acceleration area and the buffer area constitute a spiral speed transition branch route, and the reversing function route is composed of the preparation area, the transition area and the buffer area.

[0035] The low-altitude aircraft route change method, the spiral curve length L S of the spiral acceleration area is expressed as follows:

[0036]

[0037] Wherein λ is an acceleration coefficient (1.2-2), P is a spiral pitch parameter, h p is the height layer spacing.

[0038] The low-altitude aircraft route change method, the buffer area length L H is expressed as follows:

[0039]

[0040] Wherein a is the acceleration of the aircraft, d is the distance of the nearest obstacle, the route merging allowance Δ is 3m, and V1 is the target speed.

[0041] Advantages

[0042] The biggest feature of low-altitude air route is different from traditional air route, which is the high-density and high-speed safe operation requirement of the aircraft. Based on this feature, the application creatively proposes a low-altitude aircraft air route change method, which can meet the strong adaptability of large-scale unmanned aerial vehicles in the process of high-speed operation in three-dimensional layered air route, when facing task change or flight state adjustment. The aircraft can not only change the flight state in real time, but also minimize the interference of the high-speed operation of the aircraft in the original air route. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The figure is a schematic diagram of the unmanned aerial vehicle air route change process of the application;

[0044] Figure 2 The figure is a global schematic diagram of the air route model of the low-altitude aircraft air route change method of the application;

[0045] Figure 3 The figure is a profile diagram of the reversing branch air route model of the low-altitude aircraft air route change method of the application;

[0046] Figure 4 The figure is a profile diagram of the airspeed transition branch air route model of the low-altitude aircraft air route change method of the application. DETAILED DESCRIPTION

[0047] In order to make the purpose and technical scheme of the embodiments of the application clearer, the technical scheme of the embodiments of the application will be described clearly and completely below in combination with the drawings of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the described embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0048] The application proposes a low-altitude aircraft air route change method, comprising the following steps:

[0049] (1) The air route model is composed of a trunk air route network and a branch air route network, the branch air route network includes a reversing function sub-network and an airspeed transition function sub-network;

[0050] (2) The trunk air route network adopts a layered three-dimensional air route structure, each layer has an airspeed reference value (V0+ΔV) and a heading constraint (θ+Δθ), and a safe interval (H min ) is maintained between adjacent air route layers;

[0051] (3) The reversing function sub-network adopts a spiral structure, the tangent of the spiral curve is at an angle of 30°≤a≤60° with the axis of the trunk route, and the spiral radius is adjusted according to the relationship ΔR=K·h, wherein the value of K is determined by the speed and the surrounding environment of the route.

[0052] (4) The speed transition route sub-network adopts a spiral structure, the tangent of the spiral curve is at an angle of 30°≤a≤60° with the axis of the trunk route, and the spiral radius is adjusted according to the relationship ΔR=λ·ΔV / V0, wherein λ is an acceleration coefficient.

[0053] Further, the branch function route network can be distributed on both sides of the trunk route network according to the geographical conditions of the city and the flight change requirements of the unmanned aerial vehicle, and the spiral structure branch route can adopt clockwise and counterclockwise turning, respectively.

[0054] Preferably, when the unmanned aerial vehicle receives a task change notification while flying on the original route, the height layer of the route of other unmanned aerial vehicles in the minimum interference route is changed, an acceleration preparation area, a spiral acceleration area, and a buffer area should be set.

[0055] Preferably, in order to ensure flight safety, the safety interval of the unmanned aerial vehicle should be set, including the horizontal safety interval and the vertical safety interval.

[0056] Preferably, the safety interval of the unmanned aerial vehicle is calculated as follows:

[0057] The horizontal safety interval D of the unmanned aerial vehicle h The response time t of the unmanned aerial vehicle needs to be considered, the maximum braking acceleration a b , and the positioning error tolerance Δ S , which can be calculated according to the following formula

[0058]

[0059] Wherein γ is the safety factor, and the value is 1.2-1.6;

[0060] Preferably, the vertical safety interval of the unmanned aerial vehicle needs to be set in advance with a minimum forced interval, and can be adjusted according to the actual flight situation. The vertical safety interval D v The formula is:

[0061]

[0062] Wherein h min is the minimum safety interval, ρ is the air density, v z is the maximum climb rate, and η is the turbulence compensation coefficient.

[0063] Preferably, the trunk route network comprises low-speed routes, reverse routes, high-speed routes, single-layer routes composed of multiple parallel routes in the same direction, and the number of routes in the layer can be adjusted in real time according to the dynamic capacity evaluation of the route, wherein the theoretical capacity evaluation of the single-layer route can be based on the formula:

[0064]

[0065] wherein the single-layer route capacity C L is evaluated according to the number of parallel routes N L , the speed reference value V ave , the equivalent length of the aircraft L u , the gravitational acceleration g, and the horizontal safety interval D h .

[0066] Preferably, the preparation area is the original route segment area before the real-time change of the UAV, the spiral acceleration area is the spiral route for the UAV to implement speed transition away from the original route, and the buffer area is the speed buffer area for the UAV to merge into the new route, and the three constitute the spiral speed transition branch route. Similarly, the reversing branch route is composed of a preparation area, a transition area, and a buffer area, and the transition area is the area between the preparation area and the buffer area in the reversing branch route.

[0067] Preferably, the spiral curve length should consider the pitch, spiral radius, speed difference, and height layer spacing, and the spiral curve length L S of the spiral curve is:

[0068]

[0069] wherein λ is the acceleration coefficient (1.2-2), P is the pitch parameter, h p is the height layer spacing.

[0070] Preferably, the buffer area exists the merging problem of the UAV after speed transition or the speed difference problem of the UAV after reversing, in addition, a certain route merging allowance should be left, and the buffer area length L H is:

[0071]

[0072] wherein a is the acceleration of the aircraft, d is the distance to the nearest obstacle, the route merging allowance Δ is 3m, and V1 is the target speed.

[0073] Example 1:

[0074] The low-altitude route network in the core area of a city adopts the principle of "single east and double west", and adopts a three-dimensional route structure with east-west layers. The trunk route is composed of three layers, which are:

[0075] Low-speed layer L1: (60-120m, speed reference value is 10m / s, heading east);

[0076] Reverse layer L2: (120-180m, 10m / s as the reference value of the sailing speed, westward direction);

[0077] High-speed layer L3: (180-240m, 30m / s as the reference value of the sailing speed, eastward direction);

[0078] The vertical interval between adjacent layers is Hmin=60m, the branch function air route is distributed on both sides of the trunk line, the initial spiral radius of the reversing function sub-network is 150m, and the included angle between the tangent of the spiral curve and the trunk line is 45°;

[0079] Case 1 (sailing speed transition):

[0080] The running speed of the unmanned aerial vehicle in the L1 layer is 10m / s, eastward, and the unmanned aerial vehicle needs to reduce the delivery time and reach the delivery destination in advance after receiving the system command. The unmanned aerial vehicle needs to be urgently accelerated to the L3 layer, the safety factor γ is 1.4, the response time is 2s, the braking acceleration is 3m / s 2 , the positioning error tolerance Δ S is 5m, the horizontal safety interval is 35.7m, the unmanned aerial vehicle confirms that there is no conflict in the front airspace, enters the preparation area, the acceleration coefficient λ is 1.5, the spiral pitch parameter P is 80m, and the spiral curve length is 612m. After completing the acceleration, the unmanned aerial vehicle will merge into the buffer merging area, the air route merging margin Δ is 3m, the buffer area length is 56.34m, the unmanned aerial vehicle adjusts the heading angle in the buffer area, and smoothly enters the L3 high-speed layer air route.

[0081] Case 2 (heading adjustment)

[0082] The running speed of the unmanned aerial vehicle in the L1 layer is 10m / s, eastward, and the unmanned aerial vehicle needs to turn the direction after receiving the task, needs to enter the reversing function branch air route, the spiral radius is 72m, the unmanned aerial vehicle cuts into the counterclockwise spiral branch, climbs through the 72m radius spiral path and reverses the heading by 180°, the air density ρ is 1.225kg / m 3 , the maximum climbing rate v z is 5m / s, the turbulence compensation coefficient η is 1.1, the vertical interval is controlled to be 51.8m, the number of parallel air routes in the L2 layer is 3, the reference value of the sailing speed is 10m / s, the equivalent length L u of the unmanned aerial vehicle is 8m, the horizontal safety interval D h is 35.7m, and the capacity evaluation is 0.69 times / s.

[0083] The embodiments only illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the present application.

[0084] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application, which can be easily thought by those skilled in the art, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of route change for a low-altitude flying vehicle, characterized by, The steps are as follows: The air route model is constructed based on the trunk air route network and the branch air route network; The trunk air route network adopts a hierarchical three-dimensional air route structure; the branch air route network adopts a reversing function sub-network and a speed transition function sub-network; The air route changing method includes heading adjustment and speed transition: When the low-altitude aircraft receives a heading adjustment instruction, the low-altitude aircraft enters the reversing function air route in the reversing function sub-network to climb, descend, and turn, so that the low-altitude aircraft completes the heading change; When the low-altitude aircraft receives a speed transition instruction, the low-altitude aircraft enters the speed transition function air route in the speed transition function sub-network to change the speed between the layers of the hierarchical three-dimensional air route structure.

2. The air route changing method of the low-altitude aircraft according to claim 1, characterized in that: The reversing function air route adopts a spiral structure air route, the tangent of the spiral curve is at an angle of 30°≤α≤60° with the trunk air route axis in the trunk air route network, and the spiral radius is adjusted according to the following expression with the change of the height layer: ΔR=K·h wherein the value of K is determined by the speed and the environment around the air route; The speed transition function air route adopts a spiral structure air route, the tangent of the spiral curve is at an angle of 30°≤α≤60° with the trunk air route axis in the trunk air route network, and the spiral radius is adjusted according to the following expression with the change of the speed: ΔR=λ·ΔV / V0 wherein λ is an acceleration coefficient; The speed reference value of each layer in the hierarchical three-dimensional air route structure is V0+ΔV, and the heading constraint is θ+Δθ.

3. The route change method of a low-altitude flying vehicle according to claim 1 or 2, characterized by: The spiral structure of the reversing function sub-network or the spiral structure of the speed transition air route sub-network all adopt clockwise and counterclockwise turning.

4. The route change method of a low-altitude flying device according to claim 1, characterized by: The trunk air route network structure is provided with an acceleration preparation area, a spiral acceleration area, and a buffer area for the low-altitude aircraft; horizontal and vertical safety intervals are set between the low-altitude aircrafts flying in the acceleration preparation area, the spiral acceleration area, and the buffer area.

5. The route change method of a low-altitude flying vehicle according to claim 4, characterized by: The horizontal safety interval D h The expression is as follows: t is the response time of the aircraft, a b is the maximum braking acceleration, Δ S is the positioning error tolerance, γ is the safety factor, and is taken as 1.2-1.6; v is the aircraft speed; Vertical safety spacing D v Formula: where h min is the minimum safety separation, p is the air density, v z is the maximum climb rate, and η is the turbulence compensation factor.

6. The route change method of a loitering aerial vehicle according to claim 1, wherein, The trunk air route network includes low-speed air routes, reverse air routes, and high-speed air routes; The low-speed air routes, the reverse air routes, and the high-speed air routes are each composed of multiple parallel air routes in the same direction; The number of air routes in a layer can be adjusted in real time according to the air route dynamic capacity evaluation, wherein the theoretical capacity evaluation of a single layer air route can be carried out according to the formula: where C L is the single-lane route capacity, N L is the number of parallel routes being evaluated, V ave is the speed reference value, L u is the equivalent length of the aircraft, g is the acceleration due to gravity, D h is the horizontal separation safety margin.

7. The route change method of a low-altitude flying vehicle according to claim 4, characterized by, The preparation area is the original air route segment area before the low-altitude aircraft changes; The spiral acceleration area is the spiral air route for the low-altitude aircraft to implement speed transition after leaving the original air route; The buffer area is the speed buffer area for the low-altitude aircraft to merge into a new air route; The preparation area, the spiral acceleration area, and the buffer area constitute the spiral speed transition branch air route, and the reversing function air route is composed of the preparation area, the transition area, and the buffer area.

8. The route change method of a low-altitude flying vehicle according to claim 7, characterized by, The helical curve length L of the helical acceleration zone S The expression is as follows: where λ is an acceleration factor, the acceleration factor is: 1.2-2, P is a pitch parameter, h p is the height layer spacing.

9. The route change method of a low-altitude flying vehicle according to claim 4, characterized by, Buffer length L H The expression for L is as follows: wherein a is the aircraft acceleration, d is the distance to the nearest obstacle, the air route merging allowance Δ is 3m, and V1 is the target speed.

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