Dead leg identification and vertical speed stable switching correction method
By employing a multi-criteria fusion-based flight segment identification algorithm and a dynamic correction method, the problem of sudden changes in vertical speed during flight segment transitions was solved, achieving smooth transitions in vertical speed and precise altitude control, thereby improving flight stability and accuracy.
Patent Information
- Application Number
- CN202511997071.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-27
- Publication Date
- 2026-04-28
AI Technical Summary
In existing technologies, the vertical speed of an aircraft is prone to sudden changes during segment transitions, leading to attitude disturbances that affect passenger comfort and flight safety. At the same time, the segment identification logic does not comprehensively consider the flight path direction, flight time, and geometric relationships, resulting in insufficient vertical guidance accuracy.
A multi-criteria fusion algorithm for flight segment identification is adopted, which combines criteria such as along-path projection, half-plane, track angle consistency, and remaining time to comprehensively identify the current flight segment. By calculating the target vertical speed, the algorithm performs amplitude limiting, rate smoothing, and dynamic correction to achieve smooth transition control.
It achieved a smooth transition of vertical speed between flight segments, shortened the switching transition time, reduced altitude arrival error, and improved flight stability and control precision.
Smart Images
Figure CN121934582A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aerospace flight control technology and relates to a method for segment identification and smooth vertical speed switching correction, which is applied to a waypoint-based vertical navigation control method in flight management systems (FMS) and automatic flight control systems (AFCS). Background Technology
[0002] In modern civil aviation and unmanned aerial vehicle (UAV) automated flight systems, vertical navigation (VNAV) is a crucial function for achieving automatic altitude guidance. Its primary objective is to guide the aircraft to climb, cruise, or descend along a predetermined altitude trajectory within a planned sequence of waypoints.
[0003] However, in actual flight, vertical speed is affected by factors such as airflow disturbances, wind field changes, aircraft weight, and thrust limitations, resulting in errors between the actual and target vertical speeds. In existing technologies, when an aircraft transitions from one route segment to the next, it typically switches directly to the target vertical speed for the next segment. This can easily cause sudden changes in vertical speed, leading to attitude disturbances and affecting passenger comfort and flight safety.
[0004] In addition, existing flight segment identification logic often relies solely on distance thresholds for judgment, without comprehensively considering flight path direction, flight time, and geometric relationships. This can lead to premature or delayed flight segment switching, affecting the accuracy of vertical guidance.
[0005] Therefore, a control method is needed that balances the accuracy of route segment identification with the stability of vertical speed, so as to achieve continuous transition between waypoints and dynamic correction of target altitude. Summary of the Invention
[0006] The purpose of this invention is to provide a method for segment identification and smooth vertical speed switching correction, so as to solve the problems of insufficient segment identification accuracy and abrupt vertical speed switching in the prior art.
[0007] A method for segment identification and smooth vertical speed switching correction includes the following steps: Step 1: Obtain the aircraft's current position, track angle, ground speed, and waypoint sequence information; Step 2: Identify the current flight segment based on the criteria of projection along the route, half-plane, consistency of track angle, and remaining time. Step 3: When the segment switching conditions are met, update the parameters for the next segment; Step 4: Calculate the target's vertical velocity and perform amplitude limiting, rate smoothing, and dynamic correction; Step 5: Perform smooth transition control and output vertical speed command.
[0008] Furthermore, the specific criteria for projection along the path are as follows: Calculate the projected distance of the aircraft in the current flight segment direction. Lateral deviation distance :
[0009]
[0010] like and If so, the aircraft is determined to be within the flight segment.
[0011] Furthermore, the half-plane criterion is as follows: Establish the normal half-plane at the end of the current flight segment, if it satisfies:
[0012] It is then assumed that the aircraft has passed the end of the flight segment and is ready to switch.
[0013] Furthermore, the specific criteria for track angle consistency are as follows: When the aircraft's flight path angle With the heading angle of the next flight segment The included angle satisfies:
[0014] It is then assumed that the aircraft's current heading is consistent with the direction of the next flight segment. This represents the track angle difference threshold used to determine whether a flight segment needs to be switched.
[0015] Furthermore, the distance and time criteria are as follows: Calculate the distance to the end of the flight segment With remaining time ,like or If so, it is determined that the waypoint is approaching; Indicates flight speed, This indicates the set segment switching distance threshold. This indicates the set threshold for segment switching time.
[0016] Furthermore, in step 3, the segment switching logic is as follows: (a) The half-plane holds and (b) and At that time, (c)
[0017] Once any one of conditions (a), (b), or (c) is met, confirm the segment switch and update the target waypoint parameters.
[0018] Furthermore, step 4 specifically involves: Get the aircraft's current altitude Altitude of target waypoint Calculate the height difference:
[0019] Combined with the remaining time from the current location to the next waypoint Calculate the target's vertical velocity:
[0020] To prevent sudden speed changes, amplitude and rate constraints are set:
[0021]
[0022] A first-order low-pass filter is used for smooth transition:
[0023] Smoothing coefficient , The vertical velocity of the target after amplitude limiting constraint. The vertical velocity of the previous beat. For the rate of change of velocity, This is the limit value for the rate of change of velocity.
[0024] Furthermore, a hold time is set in the segment switching logic. When the switching condition is continuously met Confirm the switch after a few seconds.
[0025] This invention employs a multi-criteria fusion-based segment identification algorithm, combined with a target vertical velocity dynamic calculation model based on remaining time, to achieve smooth transition of vertical velocity between segments and real-time correction of altitude guidance. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention. Figure 2 This is a schematic diagram of the geometric relationships of the flight segment; Figure 3 This is a schematic diagram illustrating the smooth switching of vertical velocity. Figure 4 The flowchart shows the logic for determining flight segment identification. Detailed Implementation
[0028] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.
[0029] like Figure 1 As shown, the method of the present invention includes the following steps: Step 1: Obtain the aircraft's current position, track angle, ground speed, and waypoint sequence information; Step 2: Identify the current flight segment based on the criteria of projection along the route, half-plane, consistency of track angle, and remaining time. Step 3: When the segment switching conditions are met, update the parameters for the next segment; Step 4: Calculate the target's vertical velocity and perform amplitude limiting, rate smoothing, and dynamic correction; Step 5: Perform smooth transition control and output vertical speed command.
[0030] See Figure 2 Let the starting point of the current flight segment be... The destination is The destination of the next leg is The aircraft's current location is .
[0031] (1) Criterion for projection along the path Calculate the projected distance of the aircraft in the current flight segment direction. Lateral deviation distance : (1) (2) like and If so, the aircraft is determined to be within the flight segment.
[0032] (2) Half-plane criterion Establish the normal half-plane at the end of the current flight segment, if it satisfies:
[0033] It is then assumed that the aircraft has passed the end of the flight segment and is ready to switch.
[0034] (3) Track angle consistency criterion When the aircraft's flight path angle With the heading angle of the next flight segment The included angle satisfies: (3) It is then assumed that the aircraft's current heading is consistent with the direction of the next flight segment. This represents the track angle difference threshold used to determine whether a flight segment needs to be switched.
[0035] (4) Distance and time criteria Calculate the distance to the end of the flight segment With remaining time ,like or If so, it is determined that the waypoint is approaching. Indicates flight speed, This indicates the set segment switching distance threshold. This indicates the set threshold for segment switching time.
[0036] (5) Comprehensive Judgment Logic The final switching logic is as follows: (a) The half-plane holds and (b) and At that time, (c)
[0037] Once any one of conditions (a), (b), or (c) is met, confirm the segment switch and update the target waypoint parameters.
[0038] See Figure 3 Get the aircraft's current altitude Altitude of target waypoint Calculate the height difference: (4) Combined with the remaining time from the current location to the next waypoint Calculate the target's vertical velocity: (5) To prevent sudden speed changes, amplitude and rate constraints are set: (6) (Rate of change of velocity, limit value of rate of change of velocity) (7) A first-order low-pass filter is used for smooth transition: (8) Smoothing coefficient , The vertical velocity of the target after amplitude limiting constraint. This represents the vertical velocity of the previous beat.
[0039] During flight, the system continuously and dynamically corrects the target's vertical velocity based on real-time altitude difference, ground speed, and distance to ensure that the target accurately reaches the predetermined altitude at waypoints.
[0040] To avoid boundary misjudgment, a hold time is set in the segment switching logic. When the switching condition is continuously met The switch is confirmed after a few seconds. The system can also adaptively adjust the threshold according to the flight phase (climb, cruise, descent) to improve robustness.
[0041] Implementation effect Through actual flight simulation verification, the method of the present invention can significantly improve the continuity of vertical speed changes, shorten the transition time of flight segment switching by about 30%, reduce the altitude arrival error by about 40%, and effectively improve flight stability and control accuracy.
[0042] Example: Simulation verification of smooth vertical velocity switching and dynamic correction To verify the effectiveness of the proposed method for smooth switching and correction of vertical speed in waypoint vertical navigation, a simulation verification based on the MATLAB / Simulink environment was conducted. The simulation object was a typical medium-sized civil aircraft, whose flight control system includes automatic thrust control (AT), autopilot (AP), and flight management system (FMS). The simulation mainly tested the vertical speed control logic in vertical navigation (VNAV) mode.
[0043] (a) Simulation Scenarios Set the sequence of aircraft waypoints For flight, the following altitude constraints apply to each waypoint:
[0044] The aircraft's initial altitude is 8200 ft, initial vertical velocity is 0 ft / min, and ground speed is 250 kt. The simulation sampling period is 0.1 s, and the total simulation duration is 600 s.
[0045] (II) Simulation Results Figure 3 The graph illustrates the changes in vertical speed during segment transitions. As can be seen, the vertical speed did not experience abrupt changes during the transition from segment WPT1–WPT2 to WPT2–WPT3; instead, a continuous transition was achieved through amplitude limiting and smoothing filtering. The vertical speed initially decreased and then increased, subsequently stabilizing near the new target value. The entire process was smooth and without sudden jumps or oscillations.
[0046] Figure 4 The system presents the decision-making process for segment identification. It comprehensively assesses the current segment status based on three dimensions: track geometry, distance, and time, ensuring the correctness and stability of segment switching.
[0047] Simulation results show that the method proposed in this invention can achieve a smooth transition of vertical speed during waypoint switching, and at the same time, it can compensate for altitude deviation in real time through dynamic correction algorithm, so that the aircraft can accurately reach the required altitude at the target waypoint, and has good robustness and adaptability.
[0048] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.
Claims
1. A method for segment identification and smooth vertical speed switching correction, characterized in that, Includes the following steps: Step 1: Obtain the aircraft's current position, track angle, ground speed, and waypoint sequence information; Step 2: Identify the current flight segment based on the criteria of projection along the route, half-plane, consistency of track angle, and remaining time. Step 3: When the segment switching conditions are met, update the parameters for the next segment; Step 4: Calculate the target's vertical velocity and perform amplitude limiting, rate smoothing, and dynamic correction; Step 5: Perform smooth transition control and output vertical speed command.
2. The method for segment identification and smooth vertical speed switching correction according to claim 1, characterized in that, The specific criteria for projection along the path are as follows: Calculate the projected distance of the aircraft in the current flight segment direction. Lateral deviation distance : like and If so, the aircraft is determined to be within the flight segment.
3. The method for segment identification and smooth vertical speed switching correction according to claim 2, characterized in that, The half-plane criterion is as follows: Establish the normal half-plane at the end of the current flight segment, if it satisfies: It is then assumed that the aircraft has passed the end of the flight segment and is ready to switch.
4. The method for segment identification and smooth vertical speed switching correction according to claim 3, characterized in that, The specific criteria for track angle consistency are as follows: When the aircraft's flight path angle With the heading angle of the next flight segment The included angle satisfies: It is then assumed that the aircraft's current heading is consistent with the direction of the next flight segment. This represents the track angle difference threshold used to determine whether a flight segment needs to be switched.
5. The method for segment identification and smooth vertical speed switching correction according to claim 4, characterized in that, The distance and time criteria are as follows: Calculate the distance to the end of the flight segment With remaining time ,like or If so, it is determined that the waypoint is approaching; Indicates flight speed, This indicates the set segment switching distance threshold. This indicates the set threshold for segment switching time.
6. The method for segment identification and smooth vertical speed switching correction according to claim 5, characterized in that, In step 3, the segment switching logic is as follows: (a) The half-plane holds and (b) and At that time, (c) Once any one of conditions (a), (b), or (c) is met, confirm the segment switch and update the target waypoint parameters.
7. The method for segment identification and smooth vertical speed switching correction according to claim 6, characterized in that, Step 4 is as follows: Get the aircraft's current altitude Altitude of target waypoint Calculate the height difference: Combined with the remaining time from the current location to the next waypoint Calculate the target's vertical velocity: To prevent sudden speed changes, amplitude and rate constraints are set: A first-order low-pass filter is used for smooth transition: Smoothing coefficient , The vertical velocity of the target after amplitude limiting constraint. The vertical velocity of the previous beat. For the rate of change of velocity, This is the limit value for the rate of change of velocity.
8. The method for segment identification and smooth vertical speed switching correction according to claim 7, characterized in that, Set hold time in the segment switching logic When the switching condition is continuously met Confirm the switch after a few seconds.