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CN-122020958-A - Air-ground integrated collision risk assessment method applied to low-altitude airspace

CN122020958ACN 122020958 ACN122020958 ACN 122020958ACN-122020958-A

Abstract

The invention discloses an air-ground integrated collision risk assessment method applied to a low-altitude airspace, and relates to the technical field of low-altitude risk assessment; the method comprises the following steps: s1, calculating the risk probability of air collision; s2, deducing an air-ground risk evolution process; s3, evaluating the number of people affected on the ground; s4, defining the number of people affected on the ground as a comprehensive evaluation index of the air-ground integrated collision risk; the technical key points are as follows: the scheme perfects the complete conduction process from the air collision to the ground accident, creatively establishes a mathematical model to quantify the performance indexes of key evolution links such as the air collision probability, the collision penetration speed, the energy loss degree, the ground falling area and the like, and realizes the accurate depiction and evaluation of the air-ground comprehensive risk caused by the air collision; in addition, the method is oriented to urban low-altitude high-density operation scenes, can evaluate the space-to-ground risk of the urban low-altitude high-density operation scenes in real time in a complex environment with multiple invasion targets, and provides a key basis for generating and executing an intelligent collision avoidance strategy.

Inventors

  • XU YAN
  • ZHANG JINPENG
  • CAI KAIQUAN
  • LEI XUMING

Assignees

  • 北京航空航天大学

Dates

Publication Date
20260512
Application Date
20251219

Claims (10)

  1. 1. An air-ground integrated collision risk assessment method applied to a low-altitude airspace is characterized by comprising the following steps of: S1, obtaining the space positions and the speeds of the intrusion machine and the local machine, calculating the position and the speed information of the intrusion machine relative to the local machine, modeling the uncertainty of a collision area and a track, and deducing an analytic solution of the collision probability of the intrusion machine relative to the local machine in a three-dimensional space through coordinate system conversion so as to generate the air collision risk probability; S2, a risk evolution time line is established, wherein the risk evolution time line comprises a collision severity assessment model, a collision energy loss and transfer model and a falling track prediction model for predicting a falling area, the collision severity assessment model is used for judging whether an aircraft falls due to a collision event or not, the collision energy loss and transfer model is used for calculating the residual speed and the residual direction of two aircraft after collision, and if the aircraft falls, the residual speed and the residual direction are used as an initial state of a falling track; S3, estimating the number of exposed population in the falling area based on the population density data of the ground, and comprehensively establishing an influence probability model according to the shielding factors and the kinetic energy characteristics of the aircraft when the aircraft impacts the ground so as to estimate and obtain the number of people affected by the ground; And S4, defining the number of the affected persons on the ground as a comprehensive evaluation index of the air-ground integrated collision risk, and outputting an evaluation result of the air-ground integrated collision risk in real time according to the obtained airborne passengers and the number of the affected persons on the ground.
  2. 2. The method for evaluating the air-ground integrated collision risk applied to the low-altitude airspace according to claim 1, wherein the specific steps of S1 are that S1.1 models a collision area of a local machine and an invading machine, selects a cylinder as the collision area, expands the collision area on the basis of the original size, and constructs the collision area of the local machine and the invading machine as the radius of the collision area And half height The method comprises the steps of (1) modeling uncertainty of an aircraft track, S1.2, converting the coordinate system to calculate collision probability of a local machine and an invading machine, and calculating an analysis solution of the collision probability in a three-dimensional space, wherein the error envelope of the aircraft approximates to an ellipse in the horizontal direction, two axes of the ellipse are respectively along the track direction and are perpendicular to the track direction, and the positioning error of the aircraft is determined by a total system error TSE.
  3. 3. The method for evaluating the risk of an air-ground integrated collision applied to a low-altitude airspace according to claim 2, wherein S1.3 is characterized in that the position error of the aircraft is set to follow Gaussian distribution, and the position error is set to be independent in three directions of a machine body coordinate axis of the aircraft and is respectively , , Constructing a position distribution model of the local or the intrusion machine in the global coordinate system, defining a predicted time span, and then determining the predicted position of the local or the intrusion machine in the global coordinate system as The prediction error of the local or invasive machine in the machine body coordinate system is that Converting the coordinates into a matrix And obtaining the spatial distribution of the position of the local or intrusion machine ; Thus, the prediction error of the local or intrusion machine in the global coordinate system is obtained as follows: ; When the collision probability of the self-machine and the intrusion machine is calculated, the self-machine is used as a reference unmanned aerial vehicle, the intrusion machine is used as a random unmanned aerial vehicle, the prediction error of the reference unmanned aerial vehicle is superposed on the prediction error of the random unmanned aerial vehicle, the collision area of the random unmanned aerial vehicle is superposed on the collision area of the reference unmanned aerial vehicle, the reference unmanned aerial vehicle is used as an origin, the random unmanned aerial vehicle is used as a particle, a collision coordinate system is constructed, and the relative position and the combination error matrix of the reference unmanned aerial vehicle and the random unmanned aerial vehicle are as follows: ; Wherein, the For reference to the position of the drone, For the location of the random drone, , The prediction errors of the reference unmanned aerial vehicle and the random unmanned aerial vehicle in the global coordinate system are respectively, To reference the relative positions of the drones and the random drones, Representing the relative position error of the reference drone and the random drone, After calculating the collision probability of the reference unmanned aerial vehicle and the random unmanned aerial vehicle, modeling with the maximum error, namely extending the combined collision area along the direction parallel to the relative speed to form an extended collision area, wherein the length of the extended collision area depends on the encountered time, the collision probability between the reference unmanned aerial vehicle and the random unmanned aerial vehicle is equal to the integral of an error probability density function in the extended area, and decoupling the 3-D space by a coordinate transformation thought and determining the analytic solution of the integral.
  4. 4. The method for evaluating the risk of air-ground integrated collision applied to a low-altitude airspace according to claim 3, wherein S1.4 is characterized in that for the horizontal probability, the orthogonal rotation matrix H is utilized to rotate the transformed coordinate system first, so that the relative speed of the reference unmanned aerial vehicle and the random unmanned aerial vehicle is taken as the positive direction of the x-axis, and the relative speed between the two aircrafts The partial conversion rate in the conversion coordinate system is ; Then determining an integral expression for calculating two-dimensional collision probability of two aircrafts and an integral upper limit and an integral lower limit, wherein the boundary on the y-axis is the maximum and minimum value of an elliptical boundary, and the integral area on the x-axis is the area swept by the relative speed in the encountering time And The boundary distances of the y-axis in the original coordinate system and the transformation coordinate system are respectively represented by: ; Wherein, the The radius of the collision zone is combined for the local and intrusion, If order And squaring the above formula to obtain a discriminant, and making the discriminant equal to zero to obtain a vector Elements of (a) Another element Is related to the encounter time; the collision probability in the horizontal direction is expressed as: ; Wherein, the For the distance of the random drone relative to the reference drone in the y-axis direction, And The probability density functions of the standard normal distributions decoupled to the x-axis and the y-axis respectively, Representation of Is used for the function variable of (a), Representation of Is a function variable of (a).
  5. 5. A space-to-ground integrated collision risk assessment method for low-altitude airspace according to claim 3, wherein the collision probability in the vertical direction is defined as the integral of a one-dimensional normal distribution in the vertical direction of the combined collision region: ; Wherein, the In order to combine the half-height of the impact area, For the distance of the random drone relative to the reference drone in the z-axis direction, Is a one-dimensional normal distribution function, Representation of Is a function variable of (a).
  6. 6. The method for evaluating the air-ground integrated collision risk applied to the low-altitude airspace according to claim 1 is characterized by comprising the following specific steps of S2.1, analyzing an evolution mechanism of an air risk to a ground risk, constructing an air-ground risk evolution time line, and covering a risk evolution process after the collision between a local machine and an intrusion machine according to different intrusion targets; S2.2, modeling a falling track of the aircraft, namely, the aircraft is considered to be severely damaged by a structure after collision and falling, the aircraft loses aerodynamic characteristics, and the falling track is modeled in a free falling form; The fall process is decoupled into horizontal and vertical components, and the corresponding differential equations are: ; Wherein, the For the horizontal speed at the moment of initial falling, define And The speeds in the horizontal direction and the vertical direction respectively, And Acceleration in the horizontal direction and acceleration in the vertical direction respectively; And The speeds in the horizontal direction and the vertical direction are respectively, c represents the aerodynamic drag coefficient, and g represents the gravity acceleration; Predicting the ground impact position of the unmanned aerial vehicle given an initial descent speed and a drag coefficient, characterized by a horizontal displacement relative to the impact point, obtaining the actual impact position of the descent trajectory by superimposing the horizontal translational movements of the aircraft when the wind acts on the aircraft in a fixed direction and at a constant horizontal speed ; S2.3, predicting the falling area of the aircraft, performing multi-scene simulation on the falling track prediction model by changing the direction and the intensity of wind, analyzing the change rule of the falling track of the aircraft under different wind field conditions, and obtaining the possible impact point distribution of the aircraft on the ground based on simulation results to form an impact influence area.
  7. 7. The method for evaluating the risk of an air-ground integrated collision applied to a low-altitude airspace according to claim 6, wherein the sub-step S2.1 comprises the following steps of S2.1.1, analyzing the risk evolution process of the collision between the local machine and eVTOL as an invading machine, namely calculating the structural penetration limit of the collision severity evaluation model, and deducing the falling track and predicting the ground collision area when the relative speed exceeds the preset threshold value, wherein the method is characterized in that the method only deduces the falling track of the local machine; S2.1.2, analyzing risk evolution process of the collision between the self-aircraft and the small rotor unmanned aerial vehicle as an invading machine, namely establishing a collision energy loss and transfer model, and calculating the residual speed and direction of the two crashed aircraft as initial conditions of the deduction of the falling track; S2.1.3, establishing a collision severity assessment model according to the analysis process of S2.1.1-S2.1.2 to calculate the structural penetration limit and judge whether the collision between the machine and eVTOL occurs, simplifying the crashed fixed wing unmanned aerial vehicle into a cylinder in the collision severity assessment model, taking the crashed eVTOL surface as an inclined plane, and considering eVTOL to reach the critical condition of structural penetration when the shearing work of the cylinder on the plane is equal to the kinetic energy corresponding to the relative velocity component perpendicular to the plane, wherein the work Go of the shearing force of the cylinder on the plane is as follows: ; Wherein, the Shear force required for the cylinder to penetrate x distance; Assuming that the perpendicular component of the relative speeds of the two aircraft is the only source of kinetic energy required to penetrate the plane, eVTOL achieves the critical conditions for structural penetration: ; Wherein, the Is the angle between the relative speed and the normal vector of the plane, For the mass of an impinging fixed wing drone, For the relative speed of the two collision sides to be solved, for the conservative transmission speed evaluation result, the speed corresponding to 50% transmission probability is defined as the transmission speed, and is recorded as ; S2.1.4, establishing a collision energy loss and transfer model, wherein the model assumes that the energy loss in the collision process only occurs in the normal direction of a collision plane, and the collision between two aircrafts is regarded as two-dimensional inelastic collision, namely, the total momentum conservation of a system before and after the collision is as follows: ; Wherein, the For the mass of the impinging intrusion machine, And For the normal velocity after collision of two aircraft, And The method comprises the steps of determining a normal velocity before collision of two aircrafts, referring to a collision model of a ground vehicle, decomposing the collision into a normal component and a tangential component, defining the ratio of the normal velocity before collision to the normal velocity after collision as a recovery coefficient e, ignoring tangential impulse generated by friction in the collision in the tangential direction, and keeping the tangential component of the velocity unchanged, wherein the post-collision velocity of the aircrafts is expressed as: ; Wherein, the And As an initial condition for deriving a crash trajectory for a velocity vector of the aircraft after the collision; And The tangential velocity after collision of the aircraft is consistent with that before collision, t represents a tangential unit vector, and n represents a normal unit vector.
  8. 8. The method for evaluating the risk of an air-ground integrated collision applied to a low-altitude airspace according to claim 1, wherein the specific step of S3 is S3.1, under a windy condition, predicting the position of an aircraft striking the ground And the area of influence of a crash determined by the size of the aircraft ; S3.2, counting population density of grid area corresponding to falling position Based on the space ratio of vegetation and ground building in the falling area and the shielding buffer condition, the shielding factor of the grid area is obtained ; S3.3, operating an influence probability model, and calculating the probability of the maximum influenced degree when the unmanned aerial vehicle falls to strike a pedestrian S3.4, calculating the number of people affected by the ground: 。
  9. 9. The method for evaluating the risk of an air-ground integrated collision applied to a low-altitude airspace according to claim 1, wherein the specific steps of S4 are that S4.1, whether the two aircraft fall after collision is obtained according to an air collision risk probability and a collision severity evaluation model, the ground position after falling is predicted by combining a collision energy loss and transfer model and a falling track prediction model, and multiple simulation is carried out based on different wind speed and wind direction conditions to form a ground area after falling, and S4.2, the number of people with affected ground caused by an air collision event is calculated And simultaneously considering the number of people with the greatest affected degree of the potential ground caused by the falling of the two parties during evaluation, S4.3, calculating the number of affected people of airborne personnel caused by an air collision event S4.4, calculating an air-ground integrated risk caused by an air collision event, carrying out multi-scene simulation on the falling model by changing the direction and the intensity of wind, analyzing the change rule of the falling track of the aircraft under different wind field conditions, and obtaining the possible impact point distribution of the aircraft on the ground based on simulation results, thereby forming a falling point distribution area K, and comprehensively representing the air-ground risk of the number of people affected by the ground and the airborne aircraft as follows: ; Wherein, the K is a distribution area formed by falling points and is the risk of air-ground integrated failure, The infinitesimal representing the integral represents the space grid element contained in the fall point distribution area.
  10. 10. The method for evaluating the risk of an air-ground integrated collision applied to a low-altitude airspace according to claim 9, wherein in S4.2, the calculation basis of the number of people affected on the ground is: ; Wherein, the The number of people affected by the ground caused by the collision of two machines, Is the probability of a two-machine air collision, And Respectively showing whether the invading machine and the local machine fall after collision, if so =1 Or Indicating the falling, if Or (b) Indicating that no fall has occurred, And The number of persons who influence the intrusion machine and the intrusion machine after falling to the ground, For a set of all intrusion machines, Is an intrusion machine; in S4.3, the calculation basis of the number of affected people of the airborne personnel is: ; Wherein, the The number of passengers on board the vehicle caused by the collision of two vehicles is affected, And The number of passengers on board the intrusion machine and the local machine respectively.

Description

Air-ground integrated collision risk assessment method applied to low-altitude airspace Technical Field The invention relates to the technical field of low-altitude risk assessment, in particular to an air-ground integrated collision risk assessment method applied to a low-altitude airspace. Background In recent years, the rapid development of various unmanned and unmanned aircrafts in an urban airspace brings unprecedented challenges to public safety, wherein the aircraft air collision risk in a high-density operation environment is particularly outstanding, the life safety of passengers on board aircraft is directly threatened, and serious influences are caused on ground personnel and infrastructure by falling or fragment scattering, so that how to objectively and effectively evaluate the air-ground integrated risk caused by the aircraft collision becomes the primary problem of low-altitude traffic safety development, the urban air collision risk is probably represented by the multidimensional conduction and evolution characteristics from air collision, energy loss to descent and ground collision, the evaluation of the low-altitude collision risk is mainly concentrated on the calculation of the air collision probability and the estimation of the casualties of ground personnel at present, and an accident linkage analysis framework facing the high-density operation environment and a quantitative calculation model penetrating through the whole air-ground process are lacking, so that the technical field needs to establish a comprehensive evaluation framework capable of comprehensively describing the whole air-ground evolution process so as to push the whole conduction risk of an air collision accident from air to ground. Disclosure of Invention In order to achieve the above purpose, the invention is realized by the following technical scheme: an air-ground integrated collision risk assessment method applied to a low-altitude airspace comprises the following steps: S1, obtaining the space positions and the speeds of the intrusion machine and the local machine, calculating the position and the speed information of the intrusion machine relative to the local machine, modeling the uncertainty of a collision area and a track, and deducing an analytic solution of the collision probability of the intrusion machine relative to the local machine in a three-dimensional space through coordinate system conversion so as to generate the air collision risk probability; S2, a risk evolution time line is established, wherein the risk evolution time line comprises a collision severity assessment model, a collision energy loss and transfer model and a falling track prediction model for predicting a falling area, the collision severity assessment model is used for judging whether an aircraft falls due to a collision event or not, the collision energy loss and transfer model is used for calculating the residual speed and the residual direction of two aircraft after collision, and if the aircraft falls, the residual speed and the residual direction are used as an initial state of a falling track; S3, estimating the number of exposed population in the falling area based on the population density data of the ground, and comprehensively establishing an influence probability model according to the shielding factors and the kinetic energy characteristics of the aircraft when the aircraft impacts the ground so as to estimate and obtain the number of people affected by the ground; And S4, defining the number of the affected persons on the ground as a comprehensive evaluation index of the air-ground integrated collision risk, and outputting an evaluation result of the air-ground integrated collision risk in real time according to the obtained airborne passengers and the number of the affected persons on the ground. S1.1, modeling a collision area of the local machine and the intrusion machine, selecting a cylinder as the collision area, expanding the collision area on the basis of the original size, and constructing the collision area of the local machine and the intrusion machine as the radius of the collision areaAnd half heightThe method comprises the steps of (1) modeling uncertainty of an aircraft track, S1.2, converting the coordinate system to calculate collision probability of a local machine and an invading machine, and calculating an analysis solution of the collision probability in a three-dimensional space, wherein the error envelope of the aircraft approximates to an ellipse in the horizontal direction, two axes of the ellipse are respectively along the track direction and are perpendicular to the track direction, and the positioning error of the aircraft is determined by a total system error TSE. Further, the S1.3 process is that the position error of the aircraft is set to follow Gaussian distribution, and the position error is set to be independent in three directions of a machine body coordinate axis of the aircraft, name