A method for switching half-plane flight segments in low-altitude obstacle avoidance flight

Abstract

This invention relates to the field of helicopter flight management system technology, and in particular to a half-plane segment switching method for low-altitude obstacle avoidance flight. This method extracts flight plan information, calculates the turning direction based on the azimuth information of the preceding and following segments, and further calculates the turning angle. Based on the turning direction and angle, it calculates the azimuth of the angle bisector of the preceding and following segments, and then determines whether the helicopter meets the segment switching conditions based on the sign of its offset from the angle bisector. This segment switching method is independent of flight technical errors and significantly improves segment switching efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of helicopter flight management systems, and in particular to a method for switching flight segments during low-altitude obstacle avoidance flight of a helicopter. Background Technology

[0002] Segment switching is an important technical aspect of helicopter flight management systems, and also an indispensable function of advanced flight management systems.

[0003] Traditional switching methods rely on distance, meaning that a segment switch occurs when the straight-line distance to the next waypoint is less than a predetermined value. While this logic is simple, helicopters fly at low altitudes with short segments, large heading angle changes, and the possibility of manual pilot control. Therefore, flight errors can be significant. If the traditional distance-based switching method is continued, excessive deviations from the flight path may occur, rendering the switching strategy ineffective and causing disorganized segment switching. This situation inevitably compromises helicopter flight safety. Summary of the Invention

[0004] The purpose of this invention is to provide a half-plane segment switching method for low-altitude obstacle avoidance flight, which significantly improves the segment switching efficiency of helicopters and enhances flight safety.

[0005] The technical solution of this invention: In order to achieve the above-mentioned objective, a half-plane segment switching method for low-altitude obstacle avoidance flight is proposed, comprising the following steps:

[0006] Step 1: Based on the flight plan data, obtain the heading angles for the first and second segments respectively;

[0007] Step 2: Determine the turning direction of the segment based on the heading angles of the preceding and following segments;

[0008] Step 3: Calculate the turning angles of the preceding and following segments;

[0009] Step 4: Calculate the angle between the bisector of the turning angle of the preceding and following segments and the due north direction;

[0010] Step 5: Denote the vertical plane containing the angle bisector of the turning angle as the switching half-plane, and determine when the helicopter passes through the switching half-plane to perform a segment switch.

[0011] In one possible embodiment, the coordinates of the end point of the preceding segment are designated P0, and the heading angle of the preceding segment is χ. i The heading angle of the latter segment is χ. f In step 2, determining the turning direction of the flight segment specifically includes:

[0012] ①When When, if 0 < χf -χ i <π, the plane turns right; if or π < χ f -χ i <2π, the plane turns left;

[0013] ②When When, if 0 < χ f -χ i <π or The plane turns right; if -π < χ f -χ i <0, the plane turns left;

[0014] ③When When -π < χ f -χ i <0 or The plane turns left; if 0 < χ f -χ i <π, the plane turns right;

[0015] ④ When When -π < χ f -χ i <0, the plane turns left, if or -2π < χ f -χ i <-π, the plane turns right.

[0016] In one possible embodiment, the calculation process of the turning angle between the forward segment and the backward segment in step 3 specifically includes the following steps;

[0017] Extend the forward segment and the subsequent segment respectively. The extended lines of the forward segment and the subsequent segment intersect with a virtual circle centered at P0 at points P1 and P2. The formula for calculating the turning angle ∠P1P0P2 is as follows:

[0018]

[0019] In one possible embodiment, in step 4, the angle between one end of the angle bisector and the due north direction is denoted as the first azimuth angle. The angle between its other end and true north is denoted as the second azimuth.

[0020]

[0021] In one possible embodiment, the first azimuth angle The calculation process specifically includes the following steps:

[0022] set up Then we have:

[0023] When 0 < χ i When ≤Δχ,

[0024] When Δχ < χ i When ≤2π-Δχ,

[0025] When 2π-Δχ<χ i When <2π,

[0026] In one possible embodiment, the second azimuth angle The calculation process specifically includes the following steps:

[0027]

[0028] In one possible embodiment, the method for determining whether the helicopter has passed through the switching half-plane in step 5 specifically includes:

[0029] Once the switching half-plane is determined, the yaw distance of the helicopter to the switching half-plane is calculated every cycle. When the sign of the yaw distance changes, it is determined that the aircraft has crossed the switching half-plane and enters the next segment.

[0030] In one possible embodiment, the method for determining whether the helicopter has passed through the switching half-plane in step 5 specifically includes:

[0031] Let χ be the azimuth angle from the end point P0 of the preceding flight segment to the helicopter position P. p ,make:

[0032]

[0033] At each interval of one cycle, Δχ and Δχ' are calculated. When the sign of Δχ or Δχ' changes, it is determined that the aircraft has crossed the switching half-plane and enters the next flight segment.

[0034] The advantages and effects of this invention can be:

[0035] (1) Segment switching is not related to flight technical errors, and segment switching efficiency is significantly improved;

[0036] (2) When flying at low altitudes and where waypoints are dense, segment switching is still applicable.

[0037] (3) Support pilots to switch flight segments manually during flight. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of half-plane switching according to a preferred embodiment of the present invention. Detailed Implementation

[0039] The invention will now be further described with reference to the accompanying drawings.

[0040] Example 1

[0041] The specific steps for switching between half-plane flight segments for low-altitude obstacle avoidance flight of helicopters are as follows:

[0042] Step 1: Based on the flight plan data, obtain the heading angle parameters for the two preceding and following flight segments, such as... Figure 1 As shown, let P0 be the coordinate of the end point of the first segment, and let χ be the heading angle of the first segment. i Let the heading angle of the subsequent segment be χ. f .

[0043] Step 2: Calculate the turning direction based on the heading angles of the preceding and following segments.

[0044] Determine based on the azimuth angles of the two consecutive flight segments:

[0045] ①When When, if 0 < χ f -χ i <π, the plane turns right; if or π < χ f -χ i <2π, the plane turns left;

[0046] ②When When, if 0 < χ f -χ i <π or The plane turns right; if -π < χ f -χ i <0, the plane turns left;

[0047] ③When When -π < χ f -χ i <0 or The plane turns left; if 0 < χ f -χ i <π, the plane turns right.

[0048] ④ When When -π < χ f -χ i <0, the plane turns left, if or -2π < χ f -χ i <-π, the plane turns right.

[0049] Step 3: Calculate the turning angle.

[0050] Extending the two segments, assuming the extended lines intersect the virtual circle centered at P0 at points P1 and P2, the formula for calculating the turning angle ∠P1P0P2 is as follows:

[0051]

[0052] Step 4: Calculate the first azimuth angle of the angle bisectors of the preceding and following flight segments.

[0053] The angle between one end of the angle bisector and true north is denoted as the first azimuth. The angle between its other end and true north is denoted as the second azimuth.

[0054] First azimuth angle The calculation process specifically includes the following steps:

[0055] set up Then we have:

[0056] When 0 < χ i When ≤Δχ,

[0057] When Δχ < χ i When ≤2π-Δχ,

[0058] When 2π-Δχ<χ i When <2π,

[0059] Step 5: Calculate the second azimuth angle of the angle bisectors of the preceding and following flight segments.

[0060] Second azimuth angle The calculation process specifically includes the following steps:

[0061]

[0062] Step 6: Determine if the helicopter has passed through the switching half-plane:

[0063] After the switching half-plane is determined, the yaw distance XTK from the helicopter to the switching half-plane is calculated every 10 seconds (interval range: 20s~0.05s). Assuming the azimuth angle from the end point P0 of the flight segment to the helicopter position P is χp and the distance is |PP0|, then:

[0064]

[0065] When the yaw sign changes, it is determined that the aircraft has crossed the switching half-plane and enters the next segment.

[0066] Example 2

[0067] The specific steps for switching between half-plane flight segments for low-altitude obstacle avoidance flight of helicopters are as follows:

[0068] Step 1: Based on the flight plan data, obtain the heading angle parameters for the two segments. Denote the coordinates of the end point of the preceding segment as P0, and the heading angle of the preceding segment as χ. i Let the heading angle of the subsequent segment be χ. f .

[0069] Step 2: Calculate the turning direction based on the heading angles of the preceding and following segments.

[0070] Determine based on the azimuth angles of the two consecutive flight segments:

[0071] ①When When, if 0 < χ f -χ i <π, the plane turns right; if or π < χ f -χ i <2π, the plane turns left;

[0072] ②When When, if 0 < χ f -χ i <π or The plane turns right; if -π < χ f -χ i <0, the plane turns left;

[0073] ③When When -π < χ f -χ i <0 or The plane turns left; if 0 < χ f -χ i <π, the plane turns right.

[0074] ④ When When -π < χ f -χ i <0, the plane turns left, if or -2π < χ f -χ i <-π, the plane turns right.

[0075] Step 3: Calculate the turning angle.

[0076] Extending the two segments, assuming the extended lines intersect the virtual circle centered at P0 at points P1 and P2, the formula for calculating the turning angle ∠P1P0P2 is as follows:

[0077]

[0078] Step 4: Calculate the first azimuth angle of the angle bisectors of the preceding and following flight segments.

[0079] The angle between one end of the angle bisector and true north is denoted as the first azimuth. The angle between its other end and true north is denoted as the second azimuth.

[0080] First azimuth angle The calculation process specifically includes the following steps:

[0081] set up Then we have:

[0082] When 0 < χ i When ≤Δχ,

[0083] When Δχ < χ i When ≤2π-Δχ,

[0084] When 2π-Δχ<χ i When <2π,

[0085] Step 5: Calculate the second azimuth angle of the angle bisectors of the preceding and following flight segments.

[0086] Second azimuth angle The calculation process specifically includes the following steps:

[0087]

[0088] Step 6: Determine if the helicopter has passed through the switching half-plane:

[0089] Let χ be the azimuth angle from the end point P0 of the flight segment to the helicopter position P. p ,make:

[0090]

[0091] Every 10 seconds (interval range: 20s to 0.05s), Δχ and Δχ' are calculated. When the sign of Δχ or Δχ' changes, it is determined that the aircraft has crossed the switching half-plane and enters the next flight segment. Figure 1 As shown, when the aircraft is to the left of the angle bisector, Δχ is negative, and when it is to the right, Δχ is positive.

Claims

1. A method for switching half-plane flight segments during low-altitude obstacle avoidance flight, characterized in that: Includes the following steps: Step 1: Based on the flight plan data, obtain the heading angles for the first and second segments respectively; in Step 1, the coordinates of the endpoint of the first segment are marked as follows: The heading angle of the preceding segment is The heading angle of the latter segment is ; Step 2: Determine the turning direction of the segment based on the heading angles of the preceding and following segments; in Step 2, determining the turning direction specifically includes: ①When At that time, if The plane turns right; if or The plane turned left; ②When At that time, if or The plane turns right; if The plane turned left; ③When At that time, if or The plane turns left; if The plane turned right; ④ When At that time, if The plane turns left, if or The plane turned right; Step 3: Calculate the turning angles of the forward and backward segments; in Step 3, the calculation process of the turning angles of the forward and backward segments specifically includes the following steps; Extend the preceding segment and the following segment respectively, and the extended line of the preceding segment and the extended line of the following segment are combined with... The virtual circles centered at intersect at and Point, turning angle The calculation formula is as follows: ； Step 4: Calculate the angle between the bisector of the turning angle of the preceding and following segments and the due north direction; in Step 4, the angle between one end of the bisector and the due north direction is denoted as the first azimuth angle. The angle between its other end and due north is denoted as the second azimuth. The first azimuth angle The calculation process specifically includes the following steps: set up Then we have: when hour, , when hour, when hour, ; Step 5: The vertical plane containing the angle bisector of the turning angle is designated as the switching half-plane. When the helicopter crosses the switching half-plane, a flight segment switch is performed. The method for determining when the helicopter crosses the switching half-plane in Step 5 specifically includes: Once the switching half-plane is determined, the yaw distance of the helicopter to the switching half-plane is calculated every cycle. When the sign of the yaw distance changes, it is determined that the aircraft has crossed the switching half-plane and enters the next segment.

2. The half-plane segment switching method for low-altitude obstacle avoidance flight according to claim 1, characterized in that: Second azimuth angle The calculation process specifically includes the following steps: 。 3. The half-plane segment switching method for low-altitude obstacle avoidance flight according to claim 2, characterized in that: In step 5, the method for determining whether the helicopter has passed through the switching half-plane specifically includes: Let the endpoint of the preceding segment be... The azimuth angle to the helicopter position P is ,make: Calculate at each interval of one cycle. and ,when or When the symbol changes, it is determined that the aircraft has crossed the switching half-plane and enters the next flight segment.

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