A method for route change of a low-altitude aircraft

Abstract

The application belongs to the field of low-altitude traffic, and particularly relates to a route changing method of a low-altitude aircraft. The method is based on a route model constructed by a trunk route network and a branch route network; the trunk route network adopts a hierarchical three-dimensional route structure; the branch route network adopts a reversing function sub-network and a speed transition function sub-network; when the low-altitude aircraft receives a heading adjustment instruction, the low-altitude aircraft enters a reversing function 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 a speed transition function route in the speed transition function sub-network to change the speed between layers of the hierarchical three-dimensional route structure. The application can meet the adaptability of large-scale unmanned aerial vehicles in the process of high-speed operation in the three-dimensional hierarchical route when facing task changes or flight state adjustments.

Description

Technical Field

[0001] This invention belongs to the field of low-altitude transportation, and specifically relates to a method for changing the flight path of a low-altitude aircraft. Background Technology

[0002] With the large-scale application of urban air mobility (UAM) and logistics drones, the density of drone operations in low-altitude airspace is growing exponentially. Faced with the large-scale operation of heterogeneous aircraft in the complex low-altitude urban environment, and given the shortcomings of existing drone autonomous obstacle avoidance technology, airspace resource allocation, and automated drone control technology, ensuring the routine safe operation of large-scale aircraft is a major issue requiring further research. Low-altitude public airways can constrain the flight direction and path of massive numbers of aircraft, ensuring their orderly operation within designated flight paths. Therefore, the scientific layout of airway networks and the construction of public airways are particularly important. For real-time mission changes during large-scale aircraft operation, the proposed model is of high value in maintaining the high-speed and safe operation of large-scale aircraft within airways.

[0003] There is a lack of research on airway networks and low-altitude airway construction in low-altitude traffic scenarios. Traditional course changes occupy a large amount of airspace and take a long time. In addition, traditional UAV flights lack speed transition mechanisms, resulting in low overall operating efficiency of UAVs and making it difficult to meet the safe operation requirements of high-density, high-speed UAVs in low-altitude traffic scenarios. Summary of the Invention

[0004] To address the existing problems mentioned in the background section, this invention proposes a method for changing the flight path of a low-altitude aircraft.

[0005] The method for changing the flight path of a low-altitude aircraft according to the present invention comprises the following steps:

[0006] Route model based on trunk route network and feeder route network;

[0007] The trunk route network adopts a hierarchical three-dimensional route structure; the feeder route network consists of a direction-changing function sub-network and a speed jump function sub-network.

[0008] Route change methods include course adjustment and speed jump:

[0009] When a low-altitude aircraft receives a heading adjustment command, it enters the heading function route in the heading function subnetwork to climb, descend, and turn, thus enabling the low-altitude aircraft to complete the heading change.

[0010] When a low-altitude aircraft receives a speed jump command, it enters the speed jump function route in the speed jump function sub-network and changes its speed between the layers of the hierarchical three-dimensional route structure.

[0011] The route-changing method for low-altitude aircraft described in this invention employs a spiral structure route for the reversing function; the angle between the tangent of the spiral curve and the axis of the main airway network is 30°≤α≤60°, and the spiral radius is adjusted with altitude as follows:

[0012] ΔR=K·h

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

[0014] The speed-jump function route adopts a spiral structure, with the angle between the spiral curve tangent and the axis of the main route network being 30°≤α≤60°. The spiral radius is adjusted with speed as expressed in the following formula:

[0015] ΔR=λ·ΔV / V0

[0016] Where λ is the acceleration coefficient;

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

[0018] The route-changing method for low-altitude aircraft described in this invention employs clockwise and counterclockwise turning in both the spiral structure of the reversal function subnetwork and the spiral structure of the speed transition route subnetwork.

[0019] The method for changing the route of a low-altitude aircraft according to the present invention includes setting an acceleration preparation zone, a spiral acceleration zone, and a buffer zone for low-altitude aircraft in the trunk route network structure; and setting horizontal and vertical safety intervals between low-altitude aircraft flying in the acceleration preparation zone, spiral acceleration zone, and buffer zone.

[0020] The method for changing the flight path of a low-altitude aircraft described in this invention, wherein the horizontal safety separation D h The expression is as follows:

[0021]

[0022] t is the aircraft response time, a b For the maximum braking acceleration, Δ S The positioning error tolerance is γ, which is the safety factor, ranging from 1.2 to 1.6; v is the aircraft speed.

[0023] Vertical safety interval D v formula:

[0024]

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

[0026] The route change method for low-altitude aircraft described in this invention includes a trunk route network comprising low-speed routes, reverse routes, and high-speed routes.

[0027] Low-speed routes, reverse routes, and high-speed routes are all composed of multiple parallel routes in the same direction;

[0028] The number of routes within a layer can be adjusted in real time based on the dynamic capacity assessment of routes. The theoretical capacity assessment of a single layer of routes can be based on the formula:

[0029]

[0030] Among them, C L For single-level airway capacity, N L The evaluation is based on the number of parallel routes, V ave L is the reference value for speed. u Let D be the equivalent length of the aircraft, g be the acceleration due to gravity, and D be the acceleration due to gravity. h For horizontal safety intervals.

[0031] The method for changing the route of a low-altitude aircraft according to the present invention, wherein the preparation area is the original route segment area of ​​the low-altitude aircraft before real-time changes;

[0032] The spiral acceleration zone is the spiral path through which a low-altitude aircraft leaves its original flight path and achieves a speed jump.

[0033] The buffer zone is a speed buffer area for low-altitude aircraft merging into a new airway;

[0034] The preparation area, spiral acceleration area, and buffer zone constitute the spiral speed jump branch route, while the reversal function route consists of the preparation area, transition area, and buffer zone.

[0035] The flight path changing method for low-altitude aircraft described in this invention, wherein the spiral curve length L in the spiral acceleration zone... S The expression is as follows:

[0036]

[0037] Where λ is the acceleration coefficient (1.2-2), P is the helix pitch parameter, and h p The height is the interlayer spacing.

[0038] The route change method for low-altitude aircraft described in this invention has a buffer zone length L. H The expression is as follows:

[0039]

[0040] Where a is the aircraft acceleration, d is the distance to the nearest obstacle, the route merging margin Δ is 3m, and V1 is the target velocity.

[0041] Beneficial effects

[0042] The most significant difference between low-altitude routes and traditional routes lies in the high-density, high-speed, and safe operation requirements of aircraft. Based on this characteristic, this invention creatively proposes a route modification method for low-altitude aircraft. This method is highly adaptable to mission changes or flight status adjustments during high-speed operation of large-scale UAVs within three-dimensional layered routes. The aircraft can not only change its flight status in real time but also minimize interference from high-speed operation within the original route. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the UAV route change process of the present invention;

[0044] Figure 2 This is a global schematic diagram of the route model for the route change method of the low-altitude aircraft of the present invention.

[0045] Figure 3 This is a cross-sectional view of the reversing branch line route model of the route changing method for the low-altitude aircraft of the present invention.

[0046] Figure 4 This is a cross-sectional view of the speed transition branch route model for the route change method of the low-altitude aircraft of the present invention. Detailed Implementation

[0047] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] This invention proposes a method for changing the flight path of a low-altitude aircraft, comprising the following steps:

[0049] (1) The route model consists of a trunk route network and a feeder route network, wherein the feeder route network includes a reversal function subnetwork and a speed jump function subnetwork.

[0050] (2) The trunk route network adopts a layered three-dimensional route structure. Each layer has a speed reference value (V0+ΔV) and a heading constraint (θ+Δθ). A safe separation (H) is maintained between adjacent route layers. min );

[0051] (3) The reversing function sub-network adopts a spiral structure. The angle between the tangent of its spiral curve and the axis of the main route is 30°≤α≤60°. The spiral radius is adjusted according to the relationship ΔR=K·h as the altitude layer changes. 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, and the angle between the tangent of the spiral curve and the axis of the main route is 30°≤α≤60°. The spiral radius is adjusted according to the relationship ΔR=λ·ΔV / V0, where λ is the acceleration coefficient.

[0053] Furthermore, the aforementioned feeder route network can be distributed on both sides of the trunk route network according to the city's geographical conditions and the flight change requirements of UAVs, and the spiral structure feeder routes can adopt clockwise and counterclockwise turns respectively.

[0054] Preferably, when a UAV receives a mission change notification while flying normally along its original route, and other UAVs change their flight altitude layer within the least interference flight path, an acceleration preparation zone, a spiral acceleration zone, and a buffer zone should be set up.

[0055] Preferably, when the UAV undergoes a state change, a safety interval should be set for the UAV to ensure flight safety, including a horizontal safety interval and a vertical safety interval.

[0056] Preferably, the safe interval for drones is calculated as follows:

[0057] Horizontal safety interval D for drones h The drone's response time t and maximum braking acceleration a need to be considered. b and positioning error tolerance Δ S It can be calculated according to the following formula

[0058]

[0059] Where γ is the safety factor, with a value ranging from 1.2 to 1.6;

[0060] Preferably, the vertical safety interval for UAVs needs to be pre-set with a minimum mandatory interval, and can be adjusted according to actual flight conditions. The vertical safety interval D v formula:

[0061]

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

[0063] Preferably, the trunk route network includes low-speed routes, reverse routes, and high-speed routes. Each layer of the route network consists of multiple parallel routes traveling in the same direction. The number of routes within a layer can be adjusted in real time based on the dynamic capacity assessment of the routes. The theoretical capacity assessment of a single layer of routes can be based on the formula:

[0064]

[0065] Among them, the single-level airway capacity C L Evaluation based on the number of parallel routes N L Speed ​​reference value V ave The equivalent length L of the aircraft u Gravitational acceleration g, horizontal safety interval D h .

[0066] Preferably, the preparation area is the original route segment before the UAV changes in real time, the spiral acceleration area is the spiral route where the UAV leaves the original route and implements a speed jump, and the buffer zone is the speed buffer area where the UAV merges into the new route. These three constitute the spiral speed jump branch route. Similarly, the reversing branch route consists of the preparation area, the transition area, and the buffer zone. The transition area is the area between the preparation area and the buffer zone within the reversing branch route.

[0067] Preferably, the length of the helical curve should take into account the helical pitch, helical radius, velocity difference, and height interlayer spacing, etc., and its helical curve length L S The formula is:

[0068]

[0069] Where λ is the acceleration coefficient (1.2-2), P is the helix pitch parameter, and h p The height is the interlayer spacing.

[0070] Preferably, the buffer zone has issues related to merging after UAV acceleration jumps or speed differences after UAV reversals. Furthermore, a certain margin for route merging must be allowed, and the buffer zone length L... H The formula is:

[0071]

[0072] Where a is the aircraft acceleration, d is the distance to the nearest obstacle, the route merging margin Δ is 3m, and V1 is the target velocity.

[0073] Example 1:

[0074] The low-altitude air route network in the core area of ​​a certain city adopts the principle of "single in the east and double in the west," employing a three-dimensional air route structure with east-west hierarchical layers. The trunk air routes consist of three layers:

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

[0076] Reverse layer L2: (120-180m, speed reference value is 10m / s, heading west);

[0077] High-speed layer L3: (180-240m, reference speed value is 30m / s, heading east);

[0078] The vertical spacing between adjacent layers is Hmin = 60m. Branch line functional routes are distributed on both sides of the main line. The reversing function sub-network adopts an initial spiral radius of 150m and the spiral curve tangent is at an angle of 45° with the main line.

[0079] Case 1 (Speed ​​Leap):

[0080] A delivery drone operating at 10 m / s eastward on level L1 receives a system command to reduce delivery time and reach its destination ahead of schedule. The drone needs to urgently accelerate to level L3, with a safety factor γ of 1.4, a response time of 2 seconds, and a braking acceleration of 3 m / s². 2 Positioning error tolerance Δ S With a horizontal safety distance of 35.7m and an acceleration coefficient λ of 1.5, a helix pitch parameter P of 80m, and a helix length of 612m, the UAV enters the preparation area after confirming that there is no conflict in the airspace ahead. After acceleration, the UAV will merge its route into the buffer merging area with a merging margin Δ of 3m and a buffer zone length of 56.34m. The UAV adjusts its heading angle within the buffer zone and smoothly enters the L3 high-speed layer route.

[0081] Case 2 (Heading Adjustment)

[0082] A patrol drone on level L1, traveling eastward at a speed of 10 m / s, needs to change direction after receiving a mission. This requires entering a reversal branch path with a spiral radius of 72 m. The drone will enter a counter-clockwise spiral branch, climb along the 72 m radius spiral path, and then reverse its course 180°. Assume an air density ρ of 1.225 kg / m³. 3 Maximum rate of ascent v z The speed is 5 m / s, the turbulence compensation coefficient η is 1.1, the vertical spacing is controlled at 51.8 m, the number of parallel routes at L2 level is 3, the reference speed is 10 m / s, and the equivalent length of the UAV is L. u The horizontal safety interval is 8m. h The length is 35.7m, and the capacity assessment is 0.69 flights / second.

[0083] The embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

[0084] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for changing the route of a low-altitude aircraft, characterized in that, The steps are as follows: Route model based on trunk route network and feeder route network; The trunk route network adopts a hierarchical three-dimensional route structure; the feeder route network consists of a direction-changing function sub-network and a speed jump function sub-network. Route change methods include course adjustment and speed jump: When a low-altitude aircraft receives a heading adjustment command, it enters the heading function route in the heading function subnetwork to climb, descend, and turn, thus enabling the low-altitude aircraft to complete the heading change. When a low-altitude aircraft receives a speed jump command, it enters the speed jump function route in the speed jump function sub-network and changes its speed between the layers of the hierarchical three-dimensional route structure. The reversing function route adopts a spiral structure; the angle between the spiral curve tangent and the axis of the main airway network is 30°≤α≤60°, and the spiral radius is adjusted with the altitude layer as follows: ΔR=K·h The K value is determined by the speed and the surrounding environment of the route; The speed-jump function route adopts a spiral structure, with the angle between the spiral curve tangent and the axis of the main route network being 30°≤α≤60°. The spiral radius is adjusted with speed as expressed in the following formula: ΔR=λ·Δv / V0 Where λ is the acceleration coefficient; In the aforementioned layered three-dimensional route structure, the reference values ​​for the speed of each layer are: V0 + ΔV, and the heading constraint is θ + Δθ. The trunk air route network structure includes an acceleration preparation zone, a spiral acceleration zone, and a buffer zone for low-altitude aircraft; horizontal and vertical safety intervals are set between low-altitude aircraft flying in the acceleration preparation zone, spiral acceleration zone, and buffer zone. The preparation area refers to the original flight path section of the low-altitude aircraft before real-time changes. The spiral acceleration zone is the spiral path through which a low-altitude aircraft leaves its original flight path and achieves a speed jump. The buffer zone is a speed buffer area for low-altitude aircraft merging into a new airway; The preparation area, spiral acceleration area, and buffer zone constitute the spiral speed jump branch route, while the reversal function route consists of the preparation area, transition area, and buffer zone. The length L of the helical curve in the helical acceleration region S The expression is as follows: Where λ is the acceleration coefficient, which is 1.2-2, P is the helix pitch parameter, and h p The height is the interlayer spacing.

2. The route-changing method for a low-altitude aircraft according to claim 1, characterized in that: In the spiral structure of the reversing function subnetwork or the spiral structure of the speed jump route subnetwork, the spiral structure routes all adopt clockwise and counterclockwise turns.

3. The route-changing method for a low-altitude aircraft according to claim 1, characterized in that: The horizontal safety interval D h The expression is as follows: t is the aircraft response time, a b For the maximum braking acceleration, Δ S The positioning error tolerance is γ, which is the safety factor, ranging from 1.2 to 1.6; v is the aircraft speed. Vertical safety interval D v formula: Where h min For the minimum safe interval, ρ is the air density, v z η is the maximum climb rate, and η is the turbulence compensation coefficient.

4. The route-changing method for a low-altitude aircraft according to claim 1, characterized in that, The aforementioned trunk air route network includes low-speed routes, reverse routes, and high-speed routes; Low-speed routes, reverse routes, and high-speed routes are all composed of multiple parallel routes in the same direction; The number of routes within a layer is adjusted in real time based on the dynamic capacity assessment of routes. The theoretical capacity assessment of a single layer of routes is based on the formula: Among them, C L For single-level airway capacity, N L The evaluation is based on the number of parallel routes, V ave L is the reference value for speed. u Let D be the equivalent length of the aircraft, g be the acceleration due to gravity, and D be the acceleration due to gravity. h For horizontal safety intervals.

5. The route-changing method for a low-altitude aircraft according to claim 1, characterized in that, Buffer length L H The expression is as follows: Where a is the aircraft acceleration, d is the distance to the nearest obstacle, the route merging margin Δ is 3m, and V1 is the target velocity.

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