A method for calculating an extreme warning curve based on aircraft climb performance

Abstract

The application discloses a kind of limit warning curve calculation methods based on aircraft climbing performance, this method first generates aircraft motion trajectory model;By estimating flight intent, predict the future flight trajectory of aircraft, use collision detection model to determine whether the future flight trajectory of aircraft intersects with terrain;Calculate the terrain inclination angle, whether the minimum distance between the aircraft pull-up trajectory and terrain is greater than minimum safety distance as the judging condition for finding limit warning point, calculate limit warning curve;Finally, the limit warning curve is optimized, and the best warning curve is obtained.The method can enable the pilot to fly safely when performing combat tasks in low altitude according to the limit warning curve and to pull up to avoid obstacles at the last moment of safe flight.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alarm curve threshold calculation in the ground proximity warning system, and particularly relates to a limit alarm curve calculation method based on aircraft climb performance. BACKGROUND

[0002] Controlled Flight into Terrain (CFIT) is an aviation accident in which a plane collides with terrain due to errors when planning to land or in low-altitude combat, resulting in the plane crashing. The main causes of CFIT are distraction of the pilot, loss of consciousness caused by overload, spatial perception and orientation obstacles, and low-altitude turn visual illusion. The purpose of developing the Ground Proximity Warning System (GPWS) is to reduce the CFIT accident rate. The GPWS monitors the state of the aircraft and terrain elevation data in real time through various sensors on the aircraft, and warns the pilot to pull up the obstacle when a dangerous situation occurs.

[0003] Currently, the research on the ground proximity warning system at home and abroad mainly focuses on seven alarm modes. The system operation performance and experimental statistical method are used to compare the flight data of the aircraft with the limit data of the seven alarm modes stored in the aircraft, and the alarm envelope is given. When the flight data of the aircraft exceeds the limit data, the pilot needs to pull up the obstacle. However, this alarm method focuses on letting the pilot judge the pull-up position after the alarm signal is sent, and does not give the range of safe flight and successful pull-up obstacle, so the pilot can only judge the reasonable pull-up position according to his own flight experience. SUMMARY

[0004] OBJECTIVE

[0005] To solve the above problems, the application provides a limit alarm curve calculation method based on aircraft climb performance, which uses an intention-based trajectory prediction algorithm to enhance the accuracy of trajectory prediction. Unlike the traditional probability statistical experiment method, the limit alarm curve mathematical formula is used to accurately calculate the limit alarm point and the limit alarm curve, and the range of safe flight and successful pull-up obstacle is given, so that the pilot can safely fly and pull up the obstacle at the last moment of safe flight when performing combat tasks in low altitude according to the limit alarm curve.

[0006] TECHNICAL SOLUTION

[0007] A limit alarm curve calculation method based on aircraft climb performance, the method comprising the following steps:

[0008] Step S1, generating an aircraft motion trajectory model;

[0009] Step S2, predicting the future flight trajectory of the aircraft by estimating the flight intention, judging whether the future flight trajectory of the aircraft intersects with the terrain by using a collision detection model;

[0010] Step S3, calculating the terrain inclination angle, taking whether the minimum distance between the aircraft pull-up trajectory and the terrain is greater than the minimum safety distance as the judgment condition for finding the limit warning point, and calculating the limit warning curve;

[0011] Step S4, optimizing the limit warning curve to obtain the best warning curve.

[0012] Preferably, step S1 comprises the following steps:

[0013] Step S11, modeling the aircraft dynamics and kinematics model;

[0014] Step S12, combining the aircraft dynamics model and the kinematics model to obtain the aircraft motion trajectory model.

[0015] Preferably, the method for predicting the future flight trajectory of the aircraft according to the flight intention in step S2 is: accurately predicting the future flight trajectory of the aircraft according to the flight intention; the intention represents the flight plan and maneuver action that the aircraft may implement in the future, and is a set of structured instructions input by the pilot, which can determine how to manipulate the aircraft in a certain time range in the future;

[0016] First, the aircraft state is taken as the input of intention inference, and the intention inference formula is used to estimate the flight intention of the aircraft. The inferred intention is the intention when the cost function Ω reaches the maximum value. The intention inference calculation formula is shown in formula (3)

[0017]

[0018] In the formula, represents the inferred intention, Ω represents the cost function, κ1 and κ2 represent the intention model likelihood factor of the cost function Ω, κ1 represents the intention model likelihood factor based on the aircraft state only, κ2 represents the intention model likelihood factor of the time required to reach the specific destination-related waypoint, Θ fp represents the intention model related to the flight plan, Θ man represents the intention model related to the maneuver action;

[0019] Second, the aircraft state and the estimated flight intention are taken as the input of trajectory prediction, and the intention-based trajectory prediction algorithm is used to estimate the state of the trajectory of the aircraft from the current position to a future time t l , to obtain the first segment of the predicted trajectory; then the aircraft position at t lThe predicted position of the aircraft in the future is projected linearly to the waypoint related to the intent inference A second segment of the predicted trajectory is obtained.

[0020] Preferably, real-time three-dimensional terrain data is extracted after the future flight trajectory of the aircraft is predicted in step S2; then, in the process of predicting the flight trajectory of the aircraft, the position and height of the predicted trajectory of the aircraft are compared with the height of the terrain in the collision detection model to determine whether the future flight trajectory of the aircraft intersects with the terrain.

[0021] Preferably, step S3 comprises:

[0022] Step S31, when the future flight trajectory of the aircraft is predicted to intersect with the terrain, the intersection point information is recorded, and the terrain inclination angle is calculated;

[0023] Step S32, a judgment condition for detecting whether the aircraft obstacle avoidance is successful is given; when h min >h safe , the aircraft obstacle avoidance is successful; when h min =h safe , the aircraft obstacle avoidance is successful and the point at which the aircraft pulls up to avoid the obstacle is the limit warning point; when h min <h safe , the aircraft obstacle avoidance fails; wherein h min is the minimum distance between the flight trajectory of the aircraft and the terrain, and h safe is the minimum safety distance set according to the aircraft performance and terrain conditions; according to the judgment condition, the limit warning point is found out;

[0024] Step S33, limit warning point search method: the limit warning point is searched by bisection method, assuming that the aircraft can successfully avoid the obstacle from the point A at t0 seconds before the crash, if the aircraft can also successfully avoid the obstacle from the point B at t1=t0 / 2 seconds before the crash, it is determined whether the aircraft can successfully avoid the obstacle from t2=t1 / 2 seconds before the crash, otherwise, it is determined whether the aircraft can successfully avoid the obstacle from t2=(t0+t1) / 2 seconds before the crash, until the limit warning point C is found out that meets the accuracy requirement;

[0025] Step S34, according to the kinematic model of the aircraft and the maximum climb angle velocity ω y , the trajectory equation of the aircraft when taking the obstacle avoidance operation in the vertical direction is calculated, when the slope of the tangent line at a point of the aircraft pull-up trajectory is equal to the slope of the terrain, the distance between the aircraft pull-up trajectory and the terrain is the minimum; S32 is used as the judgment condition to determine the relationship between the minimum distance and the minimum safety distance, the limit warning point is searched by bisection method, and a series of limit warning points are obtained in combination with different flight states of the aircraft;

[0026] Step S35, the series of limit warning points are fitted into a limit warning curve by least squares method.

[0027] Preferably, step S4 comprises the following steps:

[0028] Step S41, according to the terrain condition and the pilot's endurance to overload, the limit warning point is optimized to obtain the best warning point;

[0029] Step S42, a series of best warning points are fitted into the best warning curve by the least square method.

[0030] Preferably, in the actual flight process, the maneuvering overload of the pilot when operating the aircraft to pull up the barrier should be less than the maximum overload that the pilot can bear.

[0031] Preferably, the method for calculating the terrain slope angle in step S31 is as follows: when it is predicted that the future flight track of the aircraft intersects with the terrain at D point, it is assumed that the flight is continued according to the predicted track from D point, and the height value of the corresponding terrain is taken every certain distance to obtain the terrain slope angle of the line from the point to D point.

[0032] The method can enable the pilot to safely fly when performing a combat task in low altitude according to the limit warning curve, and pull up the barrier at the last moment of safe flight. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a schematic diagram for terrain slope calculation.

[0034] Figure 2 It is a schematic diagram for limit warning point position search and aircraft pull-up barrier.

[0035] Figure 3 It is a schematic diagram for collision detection model structure.

[0036] Figure 4 、 Figure 5 It is a flowchart of a limit warning curve calculation method based on aircraft climbing performance of the application.

[0037] Figure 6 It is a sub-flowchart of step S1.

[0038] Figure 7 It is a sub-flowchart of step S2.

[0039] Figure 8 It is a sub-flowchart of step S3.

[0040] Figure 9 It is a sub-flowchart of step S4. DETAILED DESCRIPTION

[0041] The application is realized by the following technical solutions.

[0042] A method for calculating the limit warning curve of aircraft climbing performance. The limit warning curve of dangerous terrain in front of the pilot is calculated according to the requirements of the engineering field, so that the pilot can perform the obstacle avoidance operation at the last moment of safe flight according to the curve when performing low-altitude combat tasks. According to the flight state and flight intention of the aircraft, the future flight trajectory of the aircraft is predicted, and when the flight trajectory intersects with the terrain, whether the minimum distance between the aircraft lifting trajectory and the terrain is greater than the minimum safety distance is taken as the judgment condition for finding the limit warning point. The simulation calculation is carried out to obtain the limit warning curve of the aircraft. At the same time, the terrain slope and the pilot's overload are comprehensively considered, and the curve is optimized to give the best warning curve for the pilot to pull up and avoid obstacles. While meeting the flight maneuverability and concealment, the two curves provide protection for the safe flight of the pilot.

[0043] Specifically includes the following steps:

[0044] 1) According to the aircraft dynamics and kinematics model, the aircraft motion trajectory is modeled. Assuming that the aircraft is always in a moment balance state, according to the direction of external force, the projection components of each external force on the three axes of the track coordinate axis system are obtained by using the conversion relationship matrix relative to the track coordinate axis system. The aircraft mass center dynamics equation in the track coordinate axis system is:

[0045]

[0046] In the formula, P is the engine thrust, Q is the resistance, Y is the lift, G is the gravity, v is the flight speed of the aircraft, θ is the track inclination angle, ψ c is the track deflection angle, γ c is the speed axis system inclination angle, m is the mass of the aircraft, and g is the acceleration of gravity.

[0047] Ignoring the angle of attack and the angle of sideslip, the speed v is projected onto the three axes of the ground coordinate system by using the conversion relationship matrix of the speed coordinate axis system to the ground coordinate axis system. In the case of known initial coordinate position (x d0 ,y d0 ,z d0 ) of the aircraft, the variation law of the position (x d ,y d ,z d ) of the aircraft in the ground coordinate axis system with time is obtained, as shown in formula (2).

[0048]

[0049] 2) Accurate prediction of the future flight trajectory of the aircraft according to the flight intent. The intent represents the flight plan and maneuver actions that the aircraft can possibly implement in the future, and is a set of structured instructions input by the pilot, which can determine how to manipulate the aircraft in a certain time range in the future.

[0050] First, the aircraft state is taken as the input of intent inference, and the intent inference formula is used to estimate the flight intent of the aircraft. The inferred intent is the intent that makes the cost function Ω reach the maximum value. The intent inference calculation formula is shown in formula (3).

[0051]

[0052] In the formula, represents the inferred intent, Ω represents the cost function, κ1 and κ2 represent the intent model likelihood factors of the cost function Ω, κ1 represents the intent model likelihood factor based only on the aircraft state, κ2 represents the intent model likelihood factor of the time required to reach the specific destination-related waypoint, Θ fp represents the intent model related to the flight plan, Θ man represents the intent model related to the maneuver action.

[0053] Second, the aircraft state and the estimated flight intent are taken as the input of trajectory prediction, and the intent-based trajectory prediction algorithm is used to estimate the trajectory of the aircraft from the current position to a future time t l The first segment of the predicted trajectory is obtained; then the predicted position of the aircraft at t l is projected linearly to the waypoint related to intent inference to obtain the second segment of the predicted trajectory.

[0054] 3) Determine whether the future flight trajectory of the aircraft intersects with the terrain using a collision detection model. The collision detection model takes the spatial position of the aircraft, the state parameters and the three-dimensional terrain data as inputs, uses the intent-based trajectory prediction algorithm in 2) to predict the future flight trajectory of the aircraft, and compares the terrain height to determine whether the future flight trajectory of the aircraft intersects with the terrain. The structure diagram of the collision detection model is shown in Figure 3 .

[0055] 4) Calculate the terrain inclination angle. When it is predicted that the future flight trajectory of the aircraft intersects with the terrain at point D as shown in Figure 1 , it is assumed that the aircraft continues to fly forward according to the predicted trajectory from point D as the starting point, and the height values of the corresponding terrain are taken at every certain distance to obtain the terrain inclination angle of the line from the point to point D. The distance range for measuring the terrain inclination angle is set, and the maximum inclination angle in the range is taken as the reference value of the terrain inclination angle. The formula of the reference value of the terrain inclination angle θ terrain is:

[0056]

[0057] Where θ terrain Indicates the reference value of terrain inclination angle, H j 、H i represents the terrain height of the two places at different times, and S represents the horizontal distance between the two places.

[0058] 5) Calculate the limit alarm curve. The limit alarm curve is a curve fitted by a series of limit alarm points. The position of the limit alarm point is determined as follows: Figure 2 As shown. Among them, h min is the minimum distance between the aircraft flight path and the terrain, h safe The minimum safety distance is set based on the aircraft performance and terrain conditions. Figure 2 From point D in the image, we move forward from point D and search for the critical warning point using a binary search method. Assuming that the aircraft successfully avoids the obstacle by pulling out from point A t0 seconds before impact, and if the aircraft also successfully avoids the obstacle by pulling out from point B t1 = t0 / 2 seconds before impact, we determine whether the aircraft can successfully avoid the obstacle by pulling out from point B t2 = t1 / 2 seconds before impact. Otherwise, we determine whether the aircraft can successfully avoid the obstacle by pulling out from point B t2 = (t0 + t1) / 2, and so on until we find the critical warning point C that meets the accuracy requirements. Table 1 shows the criteria for determining whether the aircraft has successfully avoided the obstacle.

[0059] Table 1 Obstacle avoidance success / failure detection table

[0060] Distance relationship Obstacle avoidance success / failure <![CDATA[h min >h safe ]]> Success h min = h safe ]] Success (limit alarm point) h min <h safe ]]> Failure

[0061] The aircraft's current maximum normal overload n y , maximum climb angle θ max 、Maximum climb angular rate ω y for:

[0062]

[0063]

[0064]

[0065] From equations (2) and (7), we can get the trajectory equation of the aircraft when taking obstacle avoidance maneuvers in the vertical direction:

[0066]

[0067] In practice, θ<90°, so we can know that Equation (7) is differentiable everywhere. We can differentiate both sides of the equation:

[0068]

[0069] When the slope of the tangent at a point on the aircraft pull-up trajectory is equal to the slope of the terrain, i.e. y d ' = tan θ terrain , the distance between the aircraft pull-up trajectory and the terrain is minimum, which is the minimum distance h min .

[0070] h min = Δh cos θ terrain (12)

[0071] where Δh is the difference between the height of the aircraft and the height of the terrain in the vertical direction when the minimum distance h min is obtained. h min ≥ h safe is taken as a judgment condition for judging whether the obstacle avoidance is successful, the limit warning point is searched by the dichotomy, and in combination with different flight states of the aircraft, a limit warning curve fitted by a series of limit warning points can be obtained.

[0072] 6) Calculation of the optimal warning curve. The limit warning curve is calculated according to the maximum overload that can be borne by the pilot, and in the actual flight process, the maneuvering overload of the pilot when operating the aircraft to pull up to avoid obstacles should be less than the maximum overload that can be borne by the pilot. Therefore, the limit warning curve can be optimized according to the terrain condition and the overload borne by the pilot, and the optimal warning curve suitable for the pilot to perform the pull-up obstacle avoidance operation can be obtained.

[0073] Embodiment

[0074] Simulation scheme

[0075] The resolution of the three-dimensional terrain matrix is set to 100 m x 100 m, the total size is 30 km x 30 km, the height of the aircraft model is y0 = 2500 m, the initial speed is v0 = 400 m / s, the flight path inclination angle is θ0 = -2°, the heading angle is ψ0 = 45°, the speed roll angle is γ c = 0°, the simulation time of the aircraft motion trajectory is 70 s, the simulation interval is 25 ms, the minimum safety distance h safe = 300 m, and since the overload that can be borne by the pilot has a physiological upper limit, the normal overload is selected to be 9G when the limit warning curve is calculated. In combination with the terrain condition, the principle that the maneuvering overload should be less than 9G in the actual flight process is considered, the normal overload is selected to be 4G, and the optimal warning point and the optimal warning curve after optimization are obtained.

[0076] Specific implementation

[0077] The specific implementation steps of the limit warning curve algorithm are as follows:

[0078] Step S1, generate the aircraft motion trajectory according to the aircraft dynamics and kinematics model. For example,Figure 6 As shown in the figure, the step S1 includes the following sub-steps:

[0079] Step S11, modeling the aircraft dynamics and kinematics model;

[0080] Step S12, combining the aircraft dynamics model and kinematics model, obtaining the aircraft motion trajectory model.

[0081] Step S2, accurately predicting the future flight trajectory of the aircraft by estimating the flight intent, and determining whether the future flight trajectory of the aircraft intersects with the terrain by using the collision detection model. As shown in the figure, Figure 7 As shown in the figure, the step S2 includes the following sub-steps:

[0082] Step S21, accurately predicting the future flight trajectory of the aircraft according to the flight intent. Using the intent inference formula to obtain the intent when the cost function takes the maximum value, and performing state estimation on the position of the aircraft from the current position to a future time t according to the aircraft state and the flight intent, obtaining the first segment of the predicted trajectory; then projecting the predicted position of the aircraft at t l to the waypoint related to intent inference l to obtain the second segment of the predicted trajectory.

[0083] Step S22, extracting real-time three-dimensional terrain data;

[0084] Step S23, in the process of predicting the flight trajectory of the aircraft, constantly comparing the position and height of the predicted trajectory of the aircraft with the height of the terrain in the collision detection model, and determining whether the future flight trajectory of the aircraft intersects with the terrain.

[0085] Step S3, calculating the terrain inclination angle, taking whether the minimum distance between the aircraft pull-up trajectory and the terrain is greater than the minimum safety distance as the judgment condition for finding the limit warning point, and calculating the limit warning curve. As shown in the figure, Figure 7 As shown in the figure, the step S3 includes the following sub-steps:

[0086] Step S31, when the future flight trajectory of the aircraft is predicted to intersect with the terrain, recording the intersection point (collision point) information, and calculating the terrain inclination angle;

[0087] Step S32, giving the judgment condition for detecting whether the aircraft obstacle avoidance is successful. When h min > h safe , the aircraft obstacle avoidance is successful; when h min = h safe , the aircraft obstacle avoidance is successful and the point of the aircraft pull-up obstacle avoidance is the limit warning point; when h min < h safe , the aircraft obstacle avoidance fails. According to the judgment condition, the limit warning point is found out; ​

[0088] Step S33, the limit alarm point search method is given. The limit alarm point is searched by dichotomy. Assuming that the aircraft can successfully avoid the obstacle if it is pulled up from A point at t0 seconds before the crash, if it can successfully avoid the obstacle if it is pulled up from B point at t1=t0 / 2 seconds before the crash, it is determined whether it can successfully avoid the obstacle if it is pulled up from t2=t1 / 2 seconds before the crash, or it is determined whether it can successfully avoid the obstacle if it is pulled up from t2=(t0+t1) / 2, until the limit alarm point C is found which meets the accuracy requirement.

[0089] Step S34, the aircraft kinematics model and the maximum climb angular velocity ω y The trajectory equation of the aircraft when taking the obstacle avoidance operation in the vertical direction is calculated. When the slope of the tangent line at a point of the aircraft pull-up trajectory is equal to the slope of the terrain, the distance between the aircraft pull-up trajectory and the terrain is the smallest. S51 is taken as a judgment condition to judge the relationship between the minimum distance in S53 and the minimum safety distance. The limit alarm point is searched by dichotomy, and a series of limit alarm points are obtained in combination with different flight states of the aircraft;

[0090] Step S35, the series of limit alarm points are fitted into a limit alarm curve by the least square method.

[0091] Step S4, the limit alarm curve is optimized to obtain the best alarm curve. As shown in the figure, the step S4 includes the following sub-steps: Figure 8

[0092] Step S41, the limit alarm point is optimized according to the terrain condition and the overload borne by the pilot to obtain the best alarm point;

[0093] Step S42, the series of best alarm points are fitted into a best alarm curve by the least square method.

[0094] The above embodiments are only for illustrating the technical concept and characteristics of the present application, the purpose is to enable the skilled in the art to understand the content of the present application and to implement it, and it cannot limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit and essence of the present application should be covered in the protection scope of the present application. The technical, shape and structure parts not described in detail in the present application are all known technologies.​

Claims

1. A method for calculating a limit warning curve based on aircraft climb performance, characterized in that: The method comprises the following steps: Step S1, generating an aircraft motion trajectory model; Step S1 includes the following steps: Step S11, modeling the aircraft dynamics and kinematics models; Step S12, combining the aircraft dynamics model and the kinematics model to obtain an aircraft motion trajectory model; Step S2, predicting the future flight trajectory of the aircraft by estimating the flight intention, and using a collision detection model to determine whether the future flight trajectory of the aircraft intersects with the terrain; The method for predicting the future flight trajectory of the aircraft based on the flight intent in step S2 is as follows: accurately predicting the future flight trajectory of the aircraft based on the flight intent; the intent represents the flight plan and maneuvers that the aircraft may implement in the future, and is a set of structured instructions input by the pilot that determines how to operate the aircraft within a certain time range in the future; First, the aircraft state is used as the input of intention inference, and the intention inference formula is used to estimate the aircraft's flight intention. The inferred intention is to make the cost function The intention when the maximum value is obtained, the intention inference calculation formula is shown in formula (3) (3) Where, Indicates the intention to infer represents the cost function, and Represents the cost function The intention model likelihood factor, represents the likelihood factor of the intention model based only on the aircraft state, The intention model likelihood factor representing the time required to reach a waypoint associated with a specific destination, Represents the intent model associated with flight planning, Represents the intention model associated with the maneuver; Secondly, the aircraft state and the estimated flight intention are As the input of trajectory prediction, the intention-based trajectory prediction algorithm is used to predict the aircraft's trajectory from its current position to a certain time in the future. The trajectory of the position is estimated to obtain the first predicted trajectory; then the aircraft is The predicted position at the location is projected straight line to the waypoint associated with the inferred intent , get the second predicted trajectory; Step S3: Calculate the terrain inclination angle, use whether the minimum distance between the aircraft's pull-up trajectory and the terrain is greater than the minimum safety distance as a criterion for finding the limit warning point, and calculate the limit warning curve; Step S3 includes: Step S31, when it is predicted that the future flight trajectory of the aircraft intersects with the terrain, the intersection information is recorded and the terrain inclination angle is calculated; Step S32, gives the judgment condition of whether the obstacle avoidance of the aircraft is successful; When , the aircraft successfully avoids the obstacle; when When the aircraft successfully avoids the obstacle and the point where the aircraft pulls up to avoid the obstacle is the limit warning point; when When the aircraft fails to avoid the obstacle, is the minimum distance between the aircraft's flight path and the terrain, The minimum safe distance is set based on aircraft performance and terrain conditions; according to the judgment conditions, the limit warning point is found; Step S33, extreme warning point search method: use binary search to search extreme warning points, assuming that If you start pulling up from point A before hitting the ground, you can successfully avoid the obstacle. If the obstacle can be avoided successfully by starting to pull up from point B, it is judged that the vehicle has been pulled up from point B before hitting the ground. Seconds to start pulling up to see if the obstacle can be avoided successfully, otherwise judge from Pull up to see if the obstacle can be avoided successfully until the accuracy requirement is met and the limit warning point C is found; Step S34: Based on the aircraft kinematic model and the maximum climbing angular velocity The aircraft's trajectory equation when performing obstacle avoidance maneuvers in the vertical direction is calculated and differentiated. When the slope of the tangent line at a certain point on the aircraft's pull-up trajectory is equal to the slope of the terrain, the distance between the aircraft's pull-up trajectory and the terrain is minimized. Using S32 as a criterion, the relationship between the minimum distance and the minimum safe distance is determined. A binary search method is used to find the limit warning point, and a series of limit warning points are obtained based on the aircraft's different flight states. Step S35, fitting a series of limit alarm points into a limit alarm curve using the least squares method; Step S4, optimizing the limit alarm curve to obtain the optimal alarm curve; Step S4 includes the following steps: Step S41, optimizing the extreme warning point according to the terrain conditions and the pilot's overload to obtain the optimal warning point; Step S42: Fit a series of optimal alarm points into an optimal alarm curve using the least square method.

2. The method for calculating a limit warning curve based on aircraft climbing performance according to claim 1, characterized in that: In step S2, the real-time three-dimensional terrain data is extracted after predicting the future flight trajectory of the aircraft. Then, during the aircraft flight trajectory prediction process, the position height of the aircraft predicted trajectory is continuously compared with the terrain height in the collision detection model to determine whether the future flight trajectory of the aircraft intersects with the terrain.

3. The method for calculating a limit warning curve based on aircraft climbing performance according to claim 1, characterized in that: During actual flight, the maneuvering overload when the pilot pulls up the aircraft to avoid obstacles should be less than the maximum overload the pilot can withstand.

4. The method for calculating a limit warning curve based on aircraft climbing performance according to claim 1, characterized in that: The method for calculating the terrain inclination angle in step S31 is as follows: when it is predicted that the future flight trajectory of the aircraft intersects the terrain at point D, it is assumed that the aircraft continues to fly forward according to the predicted trajectory with point D as the starting point, and the height value of the corresponding terrain is taken at intervals to obtain the terrain inclination angle of the line connecting the point on the terrain to point D.

Images