Unpowered high-speed aircraft diving section space-time four-dimensional coordinated guidance method

Abstract

The invention discloses a space-time four-dimensional coordinated guidance method for a dive section of an unpowered high-speed aircraft. The space-time four-dimensional coordinated guidance method comprises the specific steps that S1, a guidance model for dive terminal time and angle control of the aircraft is constructed; s2, diving optimal guidance meeting angle and position constraints; s3, two-stage diving space-time coordination guidance meeting the time constraint is carried out; and S4, carrying out online robustness compensation on the environment and ontology deviation. According to the method, the contradiction between time and space control in a traditional method is solved; the robustness is enhanced by means of a kinetic equation reverse solution technology, and real-time deviation estimation and compensation are achieved; meanwhile, the time control precision is improved by utilizing a two-stage switching logic and numerical integration optimization method based on terminal time prediction; according to the method, the flexibility and adaptability of guidance are improved, the robustness of the system is enhanced, and the strike precision and the overall performance of the aircraft when the aircraft executes complex tasks are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft guidance and control, and in particular relates to a time-space four-dimensional coordinated guidance method for a dive phase of an unpowered high-speed aircraft. Background Art

[0002] The dive phase, as the final stage in the flight trajectory of an unpowered hypersonic vehicle, is crucial for accurately striking targets. Dive guidance has always been a core issue for hypersonic vehicles, requiring the control of the vehicle to complete a variety of flight missions under the conditions of satisfying a variety of process constraints. In the guidance of the dive phase, angle and time constraints are two important factors, which have a significant impact on the design and application of the guidance law. Dive guidance faces challenges such as randomly variable flight environment and ontology model deviations, multiple stringent process and terminal constraints, fast-changing flight states, and complex and diverse flight missions. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a method for coordinated spatiotemporal four-dimensional guidance of an unpowered high-speed aircraft in the dive phase, so as to improve the accuracy of terminal constraints, the robustness of process deviations and the adaptability of diversified guidance tasks.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is a method for space-time four-dimensional coordinated guidance of an unpowered high-speed aircraft in a dive phase, comprising the following steps:

[0005] S1. Construct a guidance model for the aircraft's dive terminal time and angle control;

[0006] S2, optimal guidance of dive that meets angle and position constraints;

[0007] S3, two-stage dive space-time coordinated guidance that meets time constraints;

[0008] S4. Perform online robustness compensation for environment and entity deviations.

[0009] Furthermore, the specific process of S1 is as follows:

[0010] S101. Establish the aircraft motion equation:

[0011]

[0012] Where v is the speed of the aircraft relative to the earth, is the rate of change of the aircraft's velocity relative to the earth, θ is the velocity inclination, σ is the velocity azimuth measured clockwise from the north, f is the distance from the center of the earth, λ and φ are longitude and latitude respectively, ρ is the atmospheric density, m is the mass of the aircraft, and S m is the reference area of ​​the aircraft, g = μ M / r2 is the gravitational acceleration, μ M is the Earth's gravitational constant, C D With C L are the drag coefficient and lift coefficient respectively, υ is the roll angle, is the rate of change of velocity azimuth measured clockwise from the north, is the rate of change of longitude; is the latitude change rate, is the rate of change of the distance from the center of the earth, is the velocity inclination change rate;

[0013] S102, establish control amount attack angle α and roll angle υ constraints:

[0014]

[0015] Among them, α min With α max are the minimum and maximum angle of attack constraints, respectively. is the maximum rate of change of the angle of attack; is the rate of change of the roll angle; is the rate of change of the angle of attack; min With max are the minimum and maximum roll angle constraint values, is the maximum roll angle change rate;

[0016] S103, determine terminal constraints:

[0017]

[0018] For time constraints, is the velocity inclination constraint, is the azimuth constraint, is the longitude constraint, is the latitude constraint, To be highly constrained, tar represents the state at the target.

[0019] Furthermore, the specific process of S2 is as follows:

[0020] S201, decomposing the dive motion of the aircraft into the longitudinal dive plane motion and the lateral turning plane motion, wherein the longitudinal dive plane is defined as the aircraft M, the target O and the center of the earth O E The plane determined, the lateral turn plane is defined as the plane passing through the target and the center of mass and perpendicular to the longitudinal dive plane;

[0021] S202, establish the relative motion equation of the aircraft dive:

[0022]

[0023] in, is the second-order differential of the sight angle, is the second-order differential of the line-of-sight angle in the turning plane, v is the speed of the aircraft relative to the earth, is the rate of change of the aircraft's velocity relative to the earth, d is the line of sight distance from the center of mass of the aircraft to the target, is the rate of change of the line of sight distance from the center of mass of the aircraft to the target, is the rate of change of sight angle, is the rate of change of the sight angle in the turning plane, is the azimuthal rate of change of velocity in the subduction plane, is the direction angle of the speed in the turning plane;

[0024] S203, determine the velocity azimuth change rate in the line of sight coordinate system:

[0025]

[0026] in, is the velocity inclination constraint, is the position angle constraint, λ T is the actual azimuth, is the actual azimuth angle change rate, λ D is the sight angle, T g The theoretically calculated waiting time is:

[0027]

[0028] Convert the velocity azimuth change rate in the line of sight coordinate system to the velocity coordinate system:

[0029]

[0030] in and are the velocity inclination change rate and azimuth change rate required for guidance respectively; σ is the velocity azimuth measured clockwise from the north, and the earth's gravity term is compensated, so the longitudinal and lateral overloads N required for the aircraft are y 、N z for:

[0031]

[0032] Where g0 is the gravitational acceleration of the earth at sea level.

[0033] Furthermore, the two-stage dive space-time coordinated guidance in S3 includes a constant lateral maneuvering stage and an optimal guidance stage; S3 controls the terminal time by changing the switching time of the two stages.

[0034] Furthermore, when the expected waiting time Greater than the predicted waiting time t p When the aircraft is in the state of being in the horizontal direction, it will perform the maneuvering flight in the constant lateral maneuvering stage to extend the flight time; otherwise, it will switch to the optimal guidance stage until the dive guidance ends.

[0035] Furthermore, the predicted waiting time t p The specific process of determining is:

[0036]

[0037] Among them, L R is the range, R L is the aerodynamic lift, R D is the aerodynamic resistance, L Rc is the current range, L Rf is the terminal range, x c Represents the current flight state of the aircraft in the three-degree-of-freedom motion equation, represents the terminal state constraint, ρ is the atmospheric density, S m is the reference area of ​​the aircraft, v is the speed of the aircraft relative to the earth; in the prediction process, the current flight state of the aircraft x c As the initial value, use the proportional guidance function f p (PNG) Computation can satisfy the terminal state constraints guidance instructions, and using the binding drag coefficient C D and lift coefficient C L Calculate the aerodynamic force of the aircraft through repeated iterations until the target is reached. The time when the numerical integration ends is the predicted flight time t of the aircraft. p .

[0038] Furthermore, the maneuvering instruction in the constant lateral maneuvering phase is:

[0039]

[0040] Among them, N zd Overload for lateral maneuvers, is the azimuth constraint, σ v0 is the velocity azimuth at the beginning of the dive; N z is the required lateral overload; sgn() and Sign() are sign functions; where σ v0 Less than When the lateral maneuver overload N zd is negative; when σ v0 Greater than When σ v0 equal When the lateral maneuver overload N zd is 0.

[0041] Furthermore, the guidance rate of the two-stage dive space-time coordinated guidance described in S3 is:

[0042]

[0043] in, and are the velocity inclination change rate and azimuth change rate required for guidance, v is the relative speed of the aircraft to the earth, g0 is the earth's gravitational acceleration at sea level, N y 、N z is the longitudinal and lateral overload required by the aircraft, sgn() is the sign function, N zd is the lateral maneuver overload, σ v0 is the velocity azimuth at the beginning of the dive, is the azimuth constraint, t p To predict the waiting time, is the expected waiting time; based on the longitudinal and lateral overload N required by the aircraft y 、N z And lift coefficient inverse interpolation Determine the angle of attack α:

[0044]

[0045] Where m is the mass of the aircraft, S m is the aircraft reference area;

[0046] The tilt angle υ is:

[0047] υ=arctan2(N z ,N y ).

[0048] Furthermore, the specific process of S4 is as follows:

[0049] S401: Determine an estimated value of aerodynamic drag based on the aircraft mass, acceleration, and velocity inclination

[0050]

[0051] is the estimated rate of change of the spacecraft's velocity relative to the Earth, is the estimated value of velocity inclination, m is the mass of the spacecraft, and g is the gravitational acceleration;

[0052] S402, using the aircraft mass, velocity, velocity inclination and its differential, and the distance from the center of the earth, determine the estimated value of the longitudinal component of the aerodynamic lift

[0053]

[0054] is the estimated value of the velocity inclination rate of change; is the estimated distance from the center of the Earth, is the estimated velocity of the aircraft relative to the earth, υ is the roll angle;

[0055] S403: Determine the estimated value of the lateral component of the aerodynamic lift

[0056]

[0057] is the estimated value of the velocity azimuth differential; is the estimated value of latitude;

[0058] S404, based on the estimated value of the longitudinal component of aerodynamic lift and the estimated lateral component of aerodynamic lift

[0059] Determine an estimate of aerodynamic lift

[0060]

[0061] S405. Aerodynamic force under nominal conditions is:

[0062]

[0063] Among them, F aero,d is the aerodynamic drag, F aero,l is the aerodynamic lift, S m is the aircraft reference area, C D With C L is the binding drag coefficient and lift coefficient, ρ is the atmospheric density, and v is the speed of the aircraft relative to the earth;

[0064] By combining the estimated aerodynamic force with the nominal value, the aerodynamic force correction coefficient can be obtained as:

[0065]

[0066] Among them, k aero,d is the correction factor for aerodynamic drag, k aero,l is the correction coefficient of aerodynamic lift; based on the aerodynamic correction coefficient, the aerodynamic force in the terminal time numerical integration prediction is corrected;

[0067] S406, predicting the flight time t p To make revisions:

[0068]

[0069] Among them, LR is the range, R L is the aerodynamic lift, R D is the aerodynamic resistance, L Rc is the current range, L Rf is the terminal range, x c Represents the current flight state of the aircraft in the three-degree-of-freedom motion equation, represents the terminal state constraint, f p (PNG) represents the proportional guidance function.

[0070] Compared with the prior art, the beneficial effects of the present invention include the following points:

[0071] Roll angle flip optimization: The present invention can achieve effective downward pressure on the trajectory through a single roll flip, thereby satisfying multiple constraints of the terminal. This feature greatly simplifies flight path planning, improves guidance accuracy, and reduces the complexity of the aircraft's dive action.

[0072] Coordination of time control and position angle control: The two-stage guidance strategy proposed in this invention effectively combines the lateral maneuver of time control with the optimal guidance of position angle control, realizing the four-dimensional coordinated control of time and space. This method solves the contradiction between lateral maneuver and optimal guidance by flexibly adjusting the switching time between the two, ensuring the satisfaction of terminal constraints.

[0073] Enhanced robustness: By utilizing the inverse solution technology of the dynamic equations, the present invention can estimate and compensate for the deviation between the flight environment and the body model in real time during the flight, significantly enhancing the robustness of the guidance algorithm and enabling the aircraft to better adapt to uncertainties and disturbances.

[0074] Efficient time control: The two-stage guidance switching logic based on the terminal time numerical prediction is adopted to improve the accuracy of time control. The prediction accuracy is optimized by the numerical integration method to ensure that the aircraft can accurately reach the target area within the predetermined time, which is especially suitable for the terminal flight with a short flight distance.

[0075] Flexibility and adaptability: The two-stage guidance strategy of the present invention not only meets complex constraints, but also flexibly adjusts the terminal arrival time through lateral maneuvers, thereby improving the flexibility and adaptability of the guidance strategy and enabling it to cope with a variety of flight mission requirements.

[0076] In summary, the present invention provides an efficient, flexible and robust four-dimensional space-time coordinated guidance scheme for the dive phase, which greatly improves the strike accuracy and mission execution capability of unpowered high-speed aircraft. By solving the key problems in the guidance of the dive phase, the strike accuracy of the aircraft and the robustness of the control system are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0078] Figure 1 is a schematic diagram of the relative motion of diving according to an embodiment of the present invention;

[0079] Figure 2 It is a two-stage guidance control diagram of a dive according to an embodiment of the present invention;

[0080] Figure 3 Schematic diagram of two-stage guidance of dive according to an embodiment of the present invention; (a) is when the velocity azimuth angle at the beginning of dive is less than the terminal velocity azimuth angle constraint, (b) is when the velocity azimuth angle at the beginning of dive is greater than the terminal velocity azimuth angle constraint;

[0081] Figure 4 1 is a multi-time ITACG guided trajectory curve of a dive according to an embodiment of the present invention; (a) is an angle of attack-time curve, (b) is a roll angle-time curve, (c) is a velocity tilt angle-time curve, (d) is an azimuth angle-time curve, (e) is an altitude-time curve, and (f) is a longitude-latitude-altitude curve;

[0082] Figure 5 1 is a dive multi-angle ITACG guided trajectory curve of an embodiment of the present invention; (a) is an angle of attack-time curve, (b) is a roll angle-time curve, (c) is a velocity tilt angle-time curve, (d) is an azimuth angle-time curve, (e) is an altitude-time curve, and (f) is a longitude-latitude-altitude curve;

[0083] Figure 6 It is the terminal parameter distribution of the dive ITACG random target shooting in the embodiment of the present invention; (a) is the terminal position error distribution, (b) is the terminal time distribution, (c) is the terminal velocity inclination distribution, and (d) is the terminal azimuth distribution. DETAILED DESCRIPTION

[0084] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] This embodiment provides a method for coordinated guidance of four-dimensional space-time in the dive phase of an unpowered high-speed aircraft. Specifically, it is aimed at the guidance problem of terminal time and angle control (ITACG, impacttime and angle control guidance) of the dive under complex constraints and high-agility conditions in all states, and studies a two-stage guidance strategy based on maneuverable flight and optimal guidance. The first stage is the lateral maneuver of time control, and the second stage is the optimal guidance of position and angle control. This embodiment adopts a two-stage guidance switching logic based on the numerical prediction of terminal time, and a maneuvering direction decision method based on the heading error at the beginning of the dive, so as to achieve the coordinated unification of time-controlled maneuverable flight and optimal guidance. In addition, this embodiment uses the inverse solution of the dynamic equation to estimate and compensate the flight environment and the body deviation online to enhance the robustness of the guidance algorithm.

[0086] In some specific embodiments, a method for coordinated guidance of a high-speed unpowered aircraft in four dimensions of space and time during a dive phase comprises the following steps:

[0087] S1. Constructing the ITACG guidance model for aircraft dive:

[0088] The motion description of the aircraft adopts the three-degree-of-freedom motion equation established in the ballistic coordinate system. At the same time, for a hypersonic aircraft with a large lift-to-drag ratio in the dive phase, its flight altitude is low, and the time and range are relatively short. Therefore, the aerodynamic force is small compared to the Coriolis inertial force and centrifugal inertial force caused by the rotation of the earth. Therefore, in the process of deriving the analytical guidance law, it is assumed that the earth is a non-rotating homogeneous sphere.

[0089] The three-degree-of-freedom motion equation of the aircraft is:

[0090]

[0091] Where v is the speed of the aircraft relative to the earth, is the rate of change of the aircraft's velocity relative to the earth (· represents the differential of a physical quantity), θ is the velocity inclination, σ is the velocity azimuth measured clockwise from the north, r is the distance from the center of the earth, λ and are longitude and latitude respectively. ρ is the atmospheric density, m is the mass of the aircraft, S m is the reference area of ​​the aircraft. g=μ M / r 2 is the gravitational acceleration, μ M is the Earth's gravitational constant, C D With C L are the drag coefficient and lift coefficient (functions of Mach number and angle of attack, such as CAV-H

[14] ), respectively; the control variable angle of attack α is implicit in it, and the other control variable is the roll angle υ. is the velocity angle change rate, is the rate of change of velocity azimuth measured clockwise from the north, is the rate of change of longitude; is the latitude change rate, is the rate of change of the distance from the center of the earth.

[0092] The process constraints of the aircraft in the dive phase are mainly reflected in the control capability, that is, the size of the control quantities such as the angle of attack and the roll angle, as well as the angular rate, are strictly limited.

[0093]

[0094] Among them, α m i n With α max are the minimum maximum angle of attack constraint values, is the maximum rate of change of the angle of attack; is the rate of change of the roll angle; is the rate of change of the angle of attack; min With max is the minimum maximum roll angle constraint value, is the maximum rate of change of the roll angle. The terminal constraints that the dive ITACG guidance needs to meet include the time Speed ​​inclination Azimuth longitude latitude and height

[0095]

[0096] Where tar represents the state of the target, such as t tar Indicates the time at the target.

[0097] S2. Optimal dive guidance that meets angle and position constraints

[0098] like Figure 1 As shown in the figure, the dive motion of the aircraft is decomposed into the longitudinal dive plane motion and the lateral turning plane motion; wherein the longitudinal dive plane is defined as the aircraft M, the target O and the center of the earth O E The plane determined, the lateral turn plane, is defined as the plane passing through the target and the center of mass and perpendicular to the longitudinal dive plane.

[0099] Figure 1 Where v is the velocity vector, d is the line of sight distance from the center of mass of the aircraft to the target, that is, the length of the line of sight MO, γ D is the azimuth of the velocity in the subduction plane, λ D is the sight angle, η D is the angle between the velocity direction and the line of sight. T is the angle between the velocity in the turning plane and the dive plane, γT is the direction angle of the velocity in the turning plane (the angle with the north direction), λ TT is the sight angle in the turning plane (the angle between the sight and the north direction), λ T v is the angle between the aircraft's line of sight and the true north direction in the turning plane, that is, the azimuth angle, d is the projection of the aircraft velocity in the dive plane, A is the horizontal plane containing the aircraft M, and the target coordinate system, O(T) represents the origin of the target coordinate system O-XYZ, that is, the target point. The relative motion equation of the aircraft dive is:

[0100]

[0101] Based on the optimal control theory, the velocity azimuth change rate in the line of sight coordinate system is obtained as follows:

[0102]

[0103] Where T g The theoretically calculated waiting time is:

[0104]

[0105] Since the aircraft motion model is established in the velocity coordinate system, it is necessary to convert the velocity azimuth change rate in the line of sight coordinate system to the velocity coordinate system:

[0106]

[0107] in and They are the velocity inclination and azimuth change rates required for guidance, and the earth's gravity term is further compensated, so the longitudinal and lateral overloads N y 、N z for:

[0108]

[0109] in, and are the velocity inclination angle and azimuth angle change rate required for guidance; g0 is the earth's gravitational acceleration at sea level. The control of the terminal position and angle is achieved through the control terms of angular rate and angle in the above formula.

[0110] S3. Two-stage dive space-time coordinated guidance that meets time constraints

[0111] During the dive guidance process, the aircraft actively changes the magnitude and direction of the aerodynamic force by adjusting the angle of attack and the roll angle, thereby controlling the flight direction. However, terminal time control is the control of the magnitude of the flight speed in the target direction, so the ITACG guidance of unpowered high-speed aircraft is an under-actuated long-period control problem. Figure 2 The two-stage dive ITACG guidance of this implementation method includes a constant lateral maneuvering stage and an optimal guidance stage.

[0112] The two-stage guidance strategy actually increases maneuvering flight to change the projection of the velocity vector in the target line of sight direction, thereby achieving time control. However, maneuvering flight destroys the original optimal guidance law and has an adverse effect on the satisfaction of position and angle constraints. Therefore, coordinating the relationship between maneuvering flight controlled by time and optimal guidance controlled by position angle is the core of realizing the integrated ITACG guidance task. The longer the maneuvering time of the first stage, the greater the maneuvering amplitude generated and the longer the flight time; conversely, the shorter the maneuvering time of the first stage, the smaller the maneuvering amplitude generated and the shorter the flight time. Therefore, this embodiment achieves the purpose of controlling the terminal time by changing the switching time of the two stages. During the dive flight, from the current range L Rc Numerical integration to the terminal range L Rf At, the predicted waiting time t is obtained p :

[0113]

[0114] Among them, L R is the range, R L is the aerodynamic lift, R D is the aerodynamic drag; x c Represents the current flight state of the aircraft in the three-degree-of-freedom motion equation, Indicates the terminal state constraint in S1. In the prediction process, the current flight state x of the aircraft is c As the initial value, the proportional guidance (PNG) method is used to calculate the terminal constraint The guidance instructions and the binding aerodynamic coefficient C D With C L Calculate the aerodynamic force of the aircraft through repeated iterations until the target is reached. The time when the numerical integration ends is the predicted flight time t of the aircraft. p In actual flight, when the expected waiting time is Greater than the predicted waiting time t p hour

[0115]

[0116] Indicates that the aircraft needs to perform the first stage of maneuvering flight to extend the flight time. The maneuvering instructions are:

[0117]

[0118] Among them, N zd Designed for artificial lateral maneuvering overload, is the terminal velocity azimuth constraint, σ v0 is the velocity azimuth at the beginning of the dive; N z is the overload required for the lateral direction; sgn() and Sign() are sign functions; the maneuvering flight required for the dive ITACG in the maneuvering instruction is only reflected in the lateral direction, the maneuvering amplitude is given manually, and the maneuvering direction is determined by the initial line of sight azimuth and the terminal speed azimuth constraints. The decision logic of the maneuvering direction is as follows Figure 3 as shown; Figure 3 (a), when σ v0 Less than When the maneuvering overload is negative, the aircraft speed azimuth will decrease first and then increase. On the contrary, Figure 3 (b) When σ v0 Greater than When the maneuvering overload is positive, the aircraft velocity azimuth will increase first and then decrease. As the first stage of constant value maneuvering proceeds, the heading error will become larger and larger, which means that the flight time of the aircraft will be extended. During the maneuvering flight, at regular intervals, the current flight state is used as the initial condition, and the terminal position and angle are used as the expected value to generate guidance instructions, and the predicted waiting time t is updated using the numerical prediction method. p When satisfied

[0119]

[0120] Then switch to the second stage of optimal guidance until the dive guidance ends. In summary, the dive ITACG guidance law can be expressed as:

[0121]

[0122] For a plane-symmetric aircraft, the angle of attack and the angle of roll of the guidance command for dive flight are directly controlled. To this end, based on the needs of the two directions, the overload N y With N z , the angle of attack can be obtained by inverse interpolation of aerodynamic parameters:

[0123]

[0124] in It represents the inverse interpolation calculation based on the lift coefficient. Another control variable, the roll angle υ, is:

[0125] υ=arctan2(N z ,N y )

[0126] Under the two-stage guidance strategy shown in the dive ITACG guidance law, the roll angle only flips once when the two stages switch, and under the optimal guidance of the second stage, it shows a monotonic change law, so the heading error will shrink to zero in the form of monotonic exponential decrease. The flip timing is early and the remaining space is large, so as to reduce the impact of frequent roll angle flips on guidance accuracy under limited control capability. The optimal guidance method in the second stage will control the aircraft to meet the position and angle constraints with high precision, and the mutual cooperation of the two stages can determine the lateral maneuver range, thereby controlling the terminal arrival time.

[0127] S4. Online robust compensation of environmental and entity deviations

[0128] According to the two-stage ITACG strategy of diving, accurate prediction of terminal time is one of the key factors of time control. In the data integration prediction of waiting time, only nominal models and data can be used, and the aircraft will inevitably be affected by various deviation factors during actual flight. For the dive section of unpowered flight, the aircraft is mainly affected by aerodynamic forces and the earth's gravity, and the deviation term mainly comes from aerodynamic forces. Therefore, this embodiment uses flight state parameters to estimate the aerodynamic model and atmospheric density deviation online, and compensates it in the time prediction link to improve the time prediction accuracy.

[0129] Based on the mass, acceleration, and velocity angle information of the aircraft, the aerodynamic drag can be estimated. for:

[0130]

[0131] is the estimated value of the velocity differential;

[0132] Similarly, the longitudinal component of aerodynamic lift can be estimated using the aircraft mass, velocity, velocity inclination and its derivative, and the distance from the center of the earth. for:

[0133]

[0134] is the estimated value of the velocity inclination differential;

[0135] Accordingly, the estimated lateral component of the aerodynamic lift is for:

[0136]

[0137] is the estimated value of the velocity azimuth differential;

[0138] Based on the longitudinal component of aerodynamic lift and the lateral component of aerodynamic lift The estimated value of the aerodynamic lift is:

[0139]

[0140] represents the measured or estimated value of parameter x, where the estimated value of aerodynamic force is a function of the flight state and can be given directly or indirectly by the navigation system. In addition, the aerodynamic force under nominal conditions is calculated as:

[0141]

[0142] Combining the estimated aerodynamic force with the nominal value, the aerodynamic force correction coefficient is obtained as:

[0143]

[0144] Among them, k aero,d is the correction factor for aerodynamic drag, k aero,l is the correction factor for aerodynamic lift.

[0145] Based on the above aerodynamic correction coefficient, the aerodynamic force in the terminal time numerical integration prediction is corrected.

[0146] Then the time-to-flight prediction equation was revised:

[0147]

[0148] Using the corrected aerodynamic coefficients to calculate the flight-waiting time will improve the prediction accuracy of the terminal time, thereby providing conditions for the precise control of the arrival time.

[0149] Example 1

[0150] The aircraft adopts the BTT control method, and the control parameters of angle of attack and roll angle meet the following constraints: the minimum angle of attack is α min =0°, maximum angle of attack α max =20°, maximum tilt angle υ max =180° (in the simulation calculation, the range of the roll angle is converted to [0°, 360°] or [-360°, 0°]); Maximum angle of attack change rate Maximum roll angle change rate

[0151] This embodiment verifies the performance of the dive ITACG guidance method, and sets the initial parameters of the dive flight: speed is 1810m / s, speed inclination is 0°, longitude is 115°, latitude is 25.0°, altitude is 35.4km, and initial azimuth is 85°. Set terminal parameters: longitude is 116.3°, latitude is 25.2°, altitude is 0km, speed inclination is -60°, and speed azimuth is 80°. In the dive guidance law, the largest amount of calculation comes from the numerical prediction of the terminal time, and the rest of the instructions are analytical calculations. Therefore, in order to improve the online calculation efficiency of the guidance instructions, the prediction period is set to 2s.

[0152] 1. Verification of basic performance of diving ITACG

[0153] This example verifies the performance of the guidance method in three scenarios: no time control dive guidance (Case 1), terminal time of 90s (Case 2), and 95s (Case 3). Figure 4 (a)~(f) and the simulation results in Table 1 show that the terminal arrival time is 84.06s when there is no time control. When time control is added, the terminal time error is within 0.3s. The terminal position error is less than 0.7m, the velocity inclination error is less than 0.03deg, and the azimuth error is less than 1.3deg. Taking the terminal time constraint of 90s as an example, the aircraft performs constant lateral maneuvers in the first 52s, and then enters the optimal guidance stage of the second stage with maximum capacity. During the dive flight, the roll angle only flips once when switching between the two stages, creating good conditions for meeting the terminal guidance accuracy. Under the action of the control amount angle of attack and roll angle, the azimuth angle generally shows a trend of increasing first and then decreasing. Comparing Case 2 and Case 3, it can be seen that the longer the terminal time, the longer the maneuvering time of the first stage and the larger the maneuvering range. The above simulation results show that the guidance method can meet the terminal longitude and latitude, altitude, velocity inclination and azimuth constraints with high precision, and the guidance instructions change smoothly and continuously, which is easy to implement.

[0154] Table 1. Subduction multi-time ITACG guidance results

[0155]

[0156] 2. Verification of the adaptability of the subducting ITACG

[0157] To further verify the performance of the dive ITACG, the terminal time constraint is set to 90s, the terminal velocity azimuth is 60° (Case 1), 80° (Case 2) and 100° (Case 3), and other simulation conditions remain unchanged. The simulation results are shown in Table 2 and Figure 5As shown in (a) to (f), the simulation results show that the guidance method studied in this invention can meet the terminal position, angle and time constraints with high precision. The terminal time error is within 0.2s, the position error is less than 0.7m, and the angle deviation is less than 0.6deg. In addition, combined with Figure 5 (b) Middle tilt angle and Figure 5 From the variation law of the azimuth in (d), it can be seen that when the terminal azimuth is 60 degrees, this value is less than the initial line of sight azimuth of the dive, so the aircraft performs a guidance mode of first positive maneuvering and then optimal guidance; on the contrary, when the terminal azimuth is 80 and 100 degrees, the aircraft performs a guidance mode of first negative maneuvering and then optimal guidance. The simulation results show that the dive guidance method studied in this invention can autonomously decide the initial maneuvering direction according to the relative motion state, and thus meet the terminal constraint conditions with high precision.

[0158] Table 2 Dive multi-angle ITACG guidance results

[0159]

[0160] 3. Verification of the robustness of the diving ITACG

[0161] Improving the robustness to the flight environment and body deviation is an important indicator of the diving ITACG guidance method. Therefore, in the dynamic simulation, a constant deviation is added to the atmospheric density and aerodynamic coefficient, but the guidance system is unknown to the above deviation, and the deviation can only be determined by estimation to verify the robustness of the diving ITACG method. Set the terminal parameters: longitude is 116.3°, latitude is 25.2°, altitude is 0km, velocity inclination is -60°, velocity azimuth is 80°, and expected arrival time is 90s.

[0162] The present invention conducts a maximum 15% constant limit deviation test on the atmospheric density and the aerodynamic coefficient, and the guidance results under 27 deviation combinations are shown in Table 3. It can be seen from the simulation results that under the constant limit deviation condition, the time error in all deviation cases is within 1s, and the position error is less than 3m. In addition, when both the atmospheric density and the aerodynamic coefficient decrease, the aircraft control ability is the weakest, resulting in the terminal position reaching 2.805m, the velocity inclination deviation is 1.169deg, and the azimuth error reaches 3.214deg. The above results show that the ITACG method proposed in the present invention can still meet multiple terminal constraints with high precision, and has strong robustness to environmental and entity deviations.

[0163] Table 3 Test results of the robustness of the subduction ITACG constant pull-off

[0164]

[0165]

[0166] In this embodiment, random deviations with a mean of zero and a mean square error of 3σ=15% are added to the atmospheric density and the aerodynamic coefficient, and 500 simulated target shootings are performed. The statistical characteristics and distribution of the terminal parameters are shown in Table 4 and Figure 6 As shown in (a) to (d),

[0167] The calculation results show that the maximum terminal position error is within 0.7m, the terminal time error is within 0.3s, the terminal velocity inclination error is less than 0.1deg, and the terminal velocity azimuth is less than 0.7deg, which further verifies the robustness of the guidance method.

[0168] Table 4 Statistical characteristics of random shooting of dive ITACG

[0169]

[0170] Aiming at the high-dynamic dive ITACG guidance problem under the condition of strong control capability constraint, the present invention proposes a two-stage guidance strategy of integrated time-controlled maneuvering flight and position angle control optimal guidance. Firstly, the aircraft motion model and relative motion model are established, and the optimal proportional guidance method is introduced to constrain the terminal longitude and latitude, altitude, velocity inclination and azimuth; secondly, the terminal arrival time is controlled by lateral maneuvering, and the switching logic based on the numerical prediction of terminal time is proposed, so as to realize the coordination and unification of time-controlled maneuvering flight and optimal guidance; finally, the flight environment and the body deviation are estimated and compensated online by the inverse solution of the dynamic equation, so as to enhance the robustness of the guidance algorithm.

[0171] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0172] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for coordinated guidance of unpowered high-speed aircraft in four dimensions of space and time during a dive phase, characterized in that: The following steps are involved: S1. Construct a guidance model for the aircraft's dive terminal time and angle control; S2, optimal guidance of dive that meets angle and position constraints; S3, two-stage dive space-time coordinated guidance that meets time constraints; S4. Perform online robustness compensation for environment and entity deviations.

2. The method for space-time four-dimensional coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 1, characterized in that: The specific process of S1 is as follows: S101. Establish the aircraft motion equation: Where v is the speed of the aircraft relative to the earth, is the rate of change of the aircraft's velocity relative to the earth, θ is the velocity inclination, σ is the velocity azimuth measured clockwise from the north, r is the distance from the center of the earth, λ and φ are longitude and latitude respectively, ρ is the atmospheric density, m is the mass of the aircraft, and S m is the reference area of ​​the aircraft, g = μ M / r 2 is the gravitational acceleration, μ M is the Earth's gravitational constant, C D With C L are the drag coefficient and lift coefficient respectively, υ is the roll angle, is the rate of change of velocity azimuth measured clockwise from the north, is the rate of change of longitude; is the latitude change rate, is the rate of change of the distance from the center of the earth, is the velocity inclination change rate; S102, establishing control variables attack angle α and roll angle υ constraints: Among them, α m i n and α max are the minimum and maximum angle of attack constraints, respectively. is the maximum rate of change of the angle of attack; is the rate of change of the roll angle; is the rate of change of the angle of attack; m in and υ max are the minimum and maximum roll angle constraint values, is the maximum roll angle change rate; S103, determine terminal constraints: For time constraints, is the velocity inclination constraint, is the azimuth constraint, is the longitude constraint, is the latitude constraint, To be highly constrained, tar represents the state at the target.

3. The method for four-dimensional space-time coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 1, characterized in that: The specific process of S2 is: S201, decomposing the dive motion of the aircraft into the longitudinal dive plane motion and the lateral turning plane motion, wherein the longitudinal dive plane is defined as the aircraft M, the target O and the center of the earth O E The determined plane, the lateral turning plane, is defined as the plane passing through the target and the center of mass and perpendicular to the longitudinal dive plane; S202, establish the relative motion equation of the aircraft dive: in, is the second-order differential of the sight angle, is the second-order differential of the line-of-sight angle in the turning plane, v is the speed of the aircraft relative to the earth, is the rate of change of the aircraft's velocity relative to the earth, d is the line-of-sight distance from the aircraft's center of mass to the target, and d is the rate of change of the line-of-sight distance from the aircraft's center of mass to the target. is the rate of change of sight angle, is the rate of change of the sight angle in the turning plane, is the azimuthal rate of change of velocity in the subduction plane, is the direction angle of the speed in the turning plane; S203, determine the velocity azimuth change rate in the line of sight coordinate system: in, is the velocity inclination constraint, is the position angle constraint, λ T is the actual azimuth, is the actual azimuth angle change rate, λ D is the sight angle, T g The theoretically calculated waiting time is: Convert the velocity azimuth change rate in the line of sight coordinate system to the velocity coordinate system: in and are the velocity inclination change rate and azimuth change rate required for guidance respectively; σ is the velocity azimuth measured clockwise from the north, and the earth's gravity term is compensated, so the longitudinal and lateral overloads N required for the aircraft are y 、N z for: Where g0 is the gravitational acceleration of the earth at sea level.

4. The method for four-dimensional space-time coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 1, characterized in that: The two-stage dive space-time coordinated guidance described in S3 includes a constant lateral maneuvering stage and an optimal guidance stage; S3 controls the terminal time by changing the switching time of the two stages.

5. A method for coordinated guidance of a high-speed unpowered aircraft in dive phase in four dimensions of space and time according to any one of claims 1 or 4, characterized in that: When expected flight time Greater than the predicted waiting time t p When the aircraft is in the state of being in the horizontal direction, it will perform the maneuvering flight in the constant lateral maneuvering stage to extend the flight time; otherwise, it will switch to the optimal guidance stage until the dive guidance ends.

6. The method for four-dimensional space-time coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 5, characterized in that: The predicted waiting time t p The specific process of determining is: Among them, L R is the range, R L is the aerodynamic lift, R D is the aerodynamic resistance, L Rc is the current range, L Rf is the terminal range, x c Represents the current flight state of the aircraft in the three-degree-of-freedom motion equation, represents the terminal state constraint, ρ is the atmospheric density, S m is the reference area of ​​the aircraft, v is the speed of the aircraft relative to the earth; in the prediction process, the current flight state of the aircraft x c As the initial value, use the proportional guidance function f p (PNG) Computation can satisfy the terminal state constraints guidance instructions, and using the binding drag coefficient C D and lift coefficient C L Calculate the aerodynamic force of the aircraft through repeated iterations until the target is reached. The time when the numerical integration ends is the predicted flight time t of the aircraft. p .

7. The method for four-dimensional space-time coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 5, characterized in that: The maneuvering instructions during the constant lateral maneuvering phase are: Among them, N zd Overload for lateral maneuvers, is the azimuth constraint, σ v0 is the velocity azimuth at the beginning of the dive; N z is the required lateral overload; sgn() and Sign() are sign functions; where σ v0 Less than When the lateral maneuver overload N zd is negative; when σ v0 Greater than When σ v0 equal When the lateral maneuver overload N zd is 0.

8. The method for four-dimensional space-time coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 1, characterized in that: The guidance rate of the two-stage dive space-time coordinated guidance described in S3 is: in, and are the velocity inclination change rate and azimuth change rate required for guidance, v is the relative speed of the aircraft to the earth, g0 is the earth's gravitational acceleration at sea level, N y 、N z is the longitudinal and lateral overload required by the aircraft, sgn() is the sign function, N zd is the lateral maneuver overload, σ v0 is the velocity azimuth at the beginning of the dive, is the azimuth constraint, t p To predict the waiting time, is the expected waiting time; based on the longitudinal and lateral overload N required by the aircraft y 、N z And lift coefficient inverse interpolation Determine the angle of attack α: Where m is the mass of the aircraft, S m is the aircraft reference area; The tilt angle υ is: u=arctan2(N z ,N y )。 9. The method for space-time four-dimensional coordinated guidance of a high-speed unpowered aircraft in a dive phase according to claim 1, characterized in that: The specific process of S4 is as follows: S401: Determine an estimated value of aerodynamic drag based on the aircraft mass, acceleration, and velocity inclination is the estimated rate of change of the spacecraft's velocity relative to the Earth, is the estimated value of velocity inclination, m is the mass of the spacecraft, and g is the gravitational acceleration; S402, using the aircraft mass, velocity, velocity inclination and its differential, and the distance from the center of the earth, determine the estimated value of the longitudinal component of the aerodynamic lift is the estimated value of the velocity inclination change rate; is the estimated distance from the center of the Earth, is the estimated velocity of the spacecraft relative to the earth, υ is the roll angle; S403: Determine the estimated value of the lateral component of the aerodynamic lift is the estimated value of the velocity azimuth differential; is the estimated value of latitude; S404, based on the estimated value of the longitudinal component of aerodynamic lift and the estimated lateral component of aerodynamic lift Determine an estimate of aerodynamic lift S405. Aerodynamic force under nominal conditions is: Among them, F aero,d is the aerodynamic drag, F aero,l is the aerodynamic lift, S m is the aircraft reference area, C D With C L is the binding drag coefficient and lift coefficient, ρ is the atmospheric density, and v is the speed of the aircraft relative to the earth; By combining the estimated aerodynamic force with the nominal value, the aerodynamic force correction coefficient can be obtained as: Among them, k aero,d is the correction factor for aerodynamic drag, k aero,l is the correction coefficient of aerodynamic lift; based on the aerodynamic correction coefficient, the aerodynamic force in the terminal time numerical integration prediction is corrected; S406, predicting the flight time t p To make revisions: Among them, L R is the range, R L is the aerodynamic lift, R D is the aerodynamic resistance, L Rc is the current range, L Rf is the terminal range, x c Represents the current flight state of the aircraft in the three-degree-of-freedom motion equation, represents the terminal state constraint, f p (PNG) represents the proportional guidance function.

Images