Complex no-fly zone reentry avoidance guidance method and system based on dynamic antenna method

Abstract

The invention discloses a complex no-fly zone reentry avoidance guidance method based on a dynamic antenna method, and the method comprises the steps: building a no-fly zone reentry avoidance guidance model of a hypersonic gliding aircraft; secondly, deducing a heeling angle reentry corridor by utilizing path constraint and quasi-equilibrium gliding conditions, and obtaining a heeling angle amplitude when an antenna is generated; thirdly, designing a no-fly zone evasion discrimination mechanism, eliminating evaded no-fly zones, and reducing the number of reentry guidance problem constraints; in this way, a dynamic adjustment strategy of the detection period and the detection step length is designed, and the flexibility of antenna detection is improved; and finally, an antenna generation termination condition and a scoring standard are given, and the antenna with the maximum score is preferentially selected as a guidance instruction scheme. Simulation experiment results prove that the method has good no-fly zone evasion performance and can adapt to the no-fly zone evasion problem of different shapes, numbers and motion states.

Description

Technical Field

[0001] The present invention relates to the field of hypersonic aircraft guidance, and in particular to a complex no-fly zone avoidance reentry guidance method and system based on a dynamic feeler method. Background Art

[0002] As an important development direction in the future civil aerospace field, hypersonic vehicles are experiencing a "blowout" development. In recent years, as a typical representative of hypersonic vehicles, hypersonic glide vehicles (HGV) have become an important priority development direction for the world's aerospace powers due to their advantages of high flight speed and strong maneuverability. When hypersonic glide reentry vehicles are actually flying, various obstacle areas must be considered, which brings great challenges to the guidance and control of hypersonic glide reentry vehicles. Therefore, how to involve complex no-fly zones to avoid reentry maneuvers is an urgent problem to be solved.

[0003] No-fly zone constraints usually refer to sensitive areas or obstacle areas that aircraft cannot cross during missions. Currently, common no-fly zone avoidance guidance methods mainly include heading angle corridor method and artificial potential field method. The heading angle corridor method generally analyzes the geometric position relationship between the current aircraft and the no-fly zone to obtain the feasible heading angle range for avoiding the no-fly zone. When there are multiple no-fly zones, a heading angle corridor is formed. The heading angle corridor method is intuitive, clear and easy to understand. Once a feasible heading angle corridor is found, a cluster of feasible no-fly zone avoidance flight trajectories can be obtained. However, it also has the following shortcomings: (1) It is usually assumed that the projection of the no-fly zone latitude and longitude plane is circular, and its adaptability to no-fly zones of other shapes needs further study; (2) When the number of no-fly zones increases or the distance is close, the feasible heading angle corridor considered for no-fly zone avoidance is sharply reduced, and the heading angle corridor is prone to empty set problems, and it is impossible to form an effective heading angle feasible domain. In recent years, the artificial potential field method has also been successfully applied to the HGV no-fly zone avoidance maneuver guidance problem. Usually, the gravitational and repulsive potential functions are constructed with the no-fly zone and the target point as the center. The no-fly zone generates a repulsive field on the space, and the target point generates a gravitational field on the space. The resultant force of each state point of the aircraft in the space is calculated, and then the aircraft is guided to avoid the no-fly zone and fly to the target point. The artificial potential field method has the characteristics of flexible and accurate avoidance of no-fly zones. However, for irregular-shaped no-fly zones and corridor-type no-fly zones, it is easy to encounter difficulties in potential function design, easy to fall into the problem of local optimality, and cannot solve the problem of dynamic no-fly zones, which greatly affects the no-fly zone avoidance performance of aircraft.

[0004] In recent years, the antenna method has been gradually applied to the no-fly zone avoidance and guidance problem of hypersonic vehicles due to its simple principle, easy operation, and good adaptability to complex no-fly zones. However, the standard antenna method still has the following shortcomings when dealing with no-fly zone avoidance: (1) The efficiency of antenna generation and detection is relatively low when there are a large number of no-fly zones; (2) The angle and duration of antenna detection still need to be adjusted for no-fly zones of different shapes; (3) When considering dynamic no-fly zones, the existing antenna method uses a fixed maximum amplitude roll angle detection mode, which will cause more rollovers or even avoidance failure. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art. The present invention proposes a complex no-fly zone avoidance reentry guidance method based on the dynamic antenna method, which can adaptively adjust the amplitude angle and detection period of the antenna detection, utilize the no-fly zone avoidance mechanism, reduce the number of constraints, and further improve the algorithm calculation efficiency.

[0006] The present invention provides a complex no-fly zone avoidance reentry guidance method based on a dynamic feeler method, comprising the following steps:

[0007] Step 1: For hypersonic glide vehicles, a model of the no-fly zone avoidance and reentry guidance problem for hypersonic glide vehicles is established;

[0008] Step 2: Generate antennae using the three-antennae method, determine the roll angle reentry corridor, and obtain the roll angle amplitude when the antennae are generated;

[0009] Step 3: Determine whether the current aircraft meets the no-fly zone avoidance judgment start conditions. If so, use the no-fly zone avoidance judgment mechanism to eliminate the no-fly zones that have been avoided and reduce the number of reentry guidance problem constraints; otherwise, go to step 4;

[0010] Step 4: Use the dynamic adjustment strategy of the detection period and detection step length during antenna detection to adjust the detection period and integration step length;

[0011] Step 5: Set the termination conditions for antenna generation and score them, and prioritize the antenna with the smallest score as the guidance instruction plan.

[0012] Furthermore, the specific operation steps of step 1 are:

[0013] Step 1.1: Construct a three-degree-of-freedom reentry motion model of a hypersonic glide vehicle in a semi-velocity coordinate system:

[0014]

[0015] Where r represents the relative distance from the aircraft to the center of the earth; θ and φ are the current longitude and latitude respectively; V is the speed of the aircraft relative to the earth; γ and ψ are the flight path angle and heading angle respectively; L and D are lift and drag respectively; σ is the roll angle; m is the mass of the aircraft, and g is the gravitational acceleration of the earth;

[0016] The calculation formulas for lift L and drag D are:

[0017]

[0018] Where ρ is the atmospheric density; R e is the average radius of the earth, e is a natural constant; S r is the reference cross-sectional area of ​​the aircraft; C L and C D They are lift coefficient and drag coefficient respectively:

[0019]

[0020] In the formula, l i is the lift coefficient; d i are the parameters of the drag coefficient fitting model;

[0021] Step 1.2: Define the path constraints to be met during the HGV reentry flight:

[0022]

[0023] in, n

[0024] , Refers to heat flow rate, overload and dynamic pressure respectively; K Q =7.9686×10 -5 represents the heat flow rate constant associated with the aircraft structure; n max

[0025] , They refer to the maximum allowable values ​​of heat flow rate, overload and dynamic pressure respectively;

[0026] Step 1.3: Define the quasi-equilibrium glide conditions that the HGV reentry flight must meet:

[0027]

[0028] 3. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 2, characterized in that the specific steps of step 2 include:

[0029] Step 2.1: Calculate the atmospheric density using the following formula:

[0030]

[0031] Where h = rR e ,h s is the atmospheric density correlation coefficient, R e is the average radius of the earth, e is a natural constant;

[0032] Step 2.2: Based on the path constraint and the above formula, the height-speed constraint is obtained:

[0033]

[0034] Among them, r Q (V), r n (V), r q (V) are the heat fluxes in the path constraints. Dynamic Pressure Overload n to obtain the height constraint;

[0035] Step 2.3: Based on the above formula, the quasi-balanced gliding condition defined in step 1.3 is combined to obtain the roll angle reentry corridor that satisfies the path constraint:

[0036]

[0037] r min (V) = max(r Q (V),r q (V),r n (V)

[0038] Where |σ(V) max Indicates the maximum value of the roll angle; r min (V) represents the minimum altitude that satisfies the altitude-speed constraint and quasi-balanced gliding condition.

[0039] Furthermore, the specific operation steps of step 3 are:

[0040] Step 3.1: Define the angle between the current heading of the aircraft and the line connecting the center of the no-fly zone and the center of the aircraft as δ:

[0041] δ=ψ Ni -ψ

[0042] in,

[0043]

[0044] In the formula, θ Ni and φ Ni are the longitude and latitude of the center point of the no-fly zone;

[0045] Step 3.2: Based on δ, the no-fly zone avoidance effect judgment mechanism is obtained:

[0046]

[0047] Among them, when the value of P is 1, that is, the angle δ is greater than 90°, it means that there is still a risk of entering the no-fly zone and the no-fly zone constraints need to continue to be considered; when the value of P is 0, that is, the angle δ is less than 90°, it means that the no-fly zone has been successfully avoided and the no-fly zone constraints do not need to be considered.

[0048] Furthermore, the no-fly zone avoidance judgment start condition described in step 3 includes:

[0049] Condition 1) The number of no-fly zones within a radius of 200 kilometers with the current position of the aircraft as the center is greater than 3;

[0050] Condition 2) The distance to the nearest no-fly zone center is less than 150 kilometers.

[0051] Furthermore, the steps of step 4 include:

[0052] Step 4.1: The antenna detection period T is calculated according to the following formula: d To make dynamic adjustments:

[0053]

[0054] Where mod(·) represents the floor function, d total Indicates the distance from the starting point to the target point, d k Indicates the distance of the aircraft relative to the starting point;

[0055] Step 4.2: The integration step length dT during antenna detection is calculated by the following formula: I Make adjustments:

[0056]

[0057] Further, step 5 includes the following steps:

[0058] Step 5.1: Define the termination conditions for antenna generation;

[0059] Step 5.2: The score matrix composed of the scores corresponding to each termination condition is recorded as K a =[a1,a2,a3,a4,a5], and a2=a3>a4>a1>a5>0;

[0060] Step 5.3: Arrange the distances from the end of each tentacle to the target point in ascending order, and record the score of the i-th tentacle as k bi , the closer the distance, the higher the priority of the corresponding antenna, k bi The smaller the score k of the i-th antenna bi for:

[0061] k bi =0.5+0.01*i;

[0062] Step 5.4: Calculate the final score for each antenna using the following formula:

[0063] K i =k ai ·k bi ;

[0064] Among them, k ai is the score of the termination condition of the i-th antenna;

[0065] Step 5.5: According to the score K i The antennae are sorted, and the roll angle corresponding to the antenna with the smallest score is used as the guidance instruction in the guidance cycle.

[0066] Furthermore, the termination conditions described in step 5.1 include:

[0067] C1: The flight time of the aircraft exceeds the maximum flight time of the mission;

[0068] C2: The antenna touches the edge of the no-fly zone or enters the no-fly zone;

[0069] C3: The calculated states of the tentacles at each moment exceed the maximum value of the path constraint;

[0070] C4: The heading angle deviation between the antenna tip and the target point exceeds the upper limit of 90°;

[0071] C5: The antennae reach the terminal region.

[0072] A complex no-fly zone avoidance reentry guidance system is implemented based on a complex no-fly zone avoidance reentry guidance method based on a dynamic feeler method. The system includes the following modules:

[0073] The model building module is used to build a model for the hypersonic glide vehicle's no-fly zone avoidance and reentry guidance problem;

[0074] A roll angle amplitude calculation module is used to generate feelers using a three-feeler method, determine the roll angle reentry corridor, and obtain the roll angle amplitude when the feeler is generated;

[0075] The no-fly zone avoidance judgment module is used to judge whether the current aircraft meets the no-fly zone avoidance judgment start conditions. If it does, the no-fly zone avoidance judgment mechanism is used to eliminate the no-fly zones that have been avoided, thereby reducing the number of constraints on the reentry guidance problem.

[0076] A detection adjustment module, used to adjust the detection cycle and the integration step length by using a dynamic adjustment strategy of the detection cycle and the detection step length during antenna detection;

[0077] The antenna generation module sets the termination conditions for antenna generation and scores them, giving priority to the antenna with the smallest score as the guidance instruction scheme.

[0078] Therefore, the present invention adopts the above-mentioned complex no-fly zone avoidance reentry guidance method based on the dynamic antenna method, which has the following beneficial effects:

[0079] First, the present invention adopts the antenna method for no-fly zone avoidance guidance, derives the roll angle reentry corridor through path constraints and quasi-balanced gliding conditions, and uses the maximum amplitude of the roll angle as the basis for generating the detection antenna. Compared with the generation of the detection antenna with a fixed roll angle amplitude, it has certain flexibility and is easy to calculate, which lays a foundation for subsequent antenna detection to avoid the no-fly zone;

[0080] Second, the present invention fully considers the flight characteristics of the reentry trajectory and the relative position of the no-fly zone, adopts an adaptive method to adjust the antenna detection cycle and detection duration, and updates the detection parameters at an appropriate time, which simplifies the guidance instruction solution steps and saves control resources, greatly improving the calculation efficiency. Therefore, compared with fixed cycles and detection durations, it is more suitable for the actual flight conditions of hypersonic aircraft;

[0081] Third, the dynamic tentacles complex no-fly zone avoidance reentry guidance method designed in the present invention can adapt to the no-fly zone avoidance problem of different shapes, numbers, and motion states, has good robustness, greatly improves the calculation efficiency and success rate of complex no-fly zone avoidance, and can provide a new theoretical reference for hypersonic aircraft reentry flight to avoid no-fly zones.

[0082] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 A flow chart of the method proposed by the present invention;

[0084] Figure 2 (a)-(b) are the simulation results of avoiding a single circular no-fly zone; Figure 2 (a) is the ground track, Figure 2 (b) Change of roll angle.

[0085] Figure 3 (a)-(b) are the simulation results of avoiding a single rectangular no-fly zone. Figure 3 (a) is the ground track, Figure 3 (b) Change of roll angle.

[0086] Figure 4 (a)-(b) are the simulation results of avoiding multiple circular no-fly zones. Figure 4 (a) is the ground track, Figure 4 (b) Change of roll angle.

[0087] Figure 5 (a)-(b) are the simulation results of dynamic no-fly zone avoidance. Figure 5 (a) is the ground track, Figure 5 (b) Change of roll angle. DETAILED DESCRIPTION

[0088] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the claims attached to the application.

[0089] 1. Complex no-fly zone avoidance and reentry guidance method based on dynamic antenna method

[0090] It includes the following steps:

[0091] Step 1: Taking hypersonic glide vehicles (HGV) as the research object, a model of the no-fly zone avoidance and reentry guidance problem of hypersonic glide vehicles is established;

[0092] Step 1.1: Ignore the effect of the Earth's rotation on the reentry motion and establish a three-degree-of-freedom reentry motion model for the hypersonic glide vehicle in a semi-velocity coordinate system:

[0093]

[0094] Where r represents the relative distance from the aircraft to the center of the earth; θ and φ are the current longitude and latitude respectively; V is the speed of the aircraft relative to the earth; γ and ψ are the flight path angle and heading angle respectively; L and D are lift and drag respectively; σ is the roll angle; m is the mass of the aircraft, and g is the gravitational acceleration of the earth;

[0095] The calculation formulas for lift L and drag D are:

[0096]

[0097] Where ρ is the atmospheric density, h=rR e ,h s is the atmospheric density correlation coefficient; R e is the average radius of the earth, e is a natural constant; S ris the reference cross-sectional area of ​​the aircraft; C L and C D are lift coefficient and drag coefficient respectively;

[0098] Among them, C L and C D It can be fitted to the following polynomial:

[0099]

[0100] In the formula, l i , d i (i=0,1,2,3,4) are the parameters of the lift coefficient and drag coefficient fitting models respectively;

[0101] Step 1.2: Define the path constraints to be met during the HGV reentry flight:

[0102]

[0103] In the formula, n

[0104] , Refers to heat flow rate, overload and dynamic pressure respectively; K Q =7.9686×10 -5 Js 2 / (m 3.5 kg 0.5 ) represents the heat flow rate constant associated with the aircraft structure; n max

[0105] , They refer to the maximum allowable values ​​of heat flow rate, overload and dynamic pressure respectively;

[0106] Step 1.3: Define the quasi-equilibrium glide conditions that the HGV reentry flight must meet:

[0107]

[0108] Step 2: Determine the roll angle reentry corridor and obtain the roll angle amplitude σ(V) when the antenna is generated max ;

[0109] Step 2.1: Calculate the atmospheric density using the following formula:

[0110]

[0111] Step 2.2: Combine the path constraint and equation (6) to obtain the height-speed constraint:

[0112]

[0113] In the formula, rQ (V), r n (V), r q (V) are the heat fluxes in the path constraints. Dynamic Pressure Overload n to obtain the height constraint;

[0114] Based on equation (7), combined with the quasi-balanced gliding condition equation (5), the roll angle reentry corridor that satisfies the path constraint can be obtained:

[0115]

[0116] Among them, r min (V) = max(r Q (V),r q (V),r n (V)

[0117] Where |σ(V) max Indicates the maximum amplitude of the roll angle, r min (V) represents the minimum height that satisfies equations (7) and (5).

[0118] Step 3: Use the no-fly zone avoidance judgment mechanism to eliminate the no-fly zones that have been avoided and reduce the number of constraints in the reentry guidance problem;

[0119] The HGV reentry guidance problem is regarded as an optimal control problem with complex equality and inequality constraints. When the number of no-fly zones increases, the inequality constraints that need to be solved will increase, thus affecting the efficiency of solving the guidance command. By introducing the no-fly zone avoidance effect judgment mechanism, the no-fly zones that have been successfully avoided are no longer considered to affect the subsequent guidance trajectory, thereby solving the problem of difficulty in solving the roll angle value command caused by the large number of no-fly zones. When the number of no-fly zones is far greater than 3, the no-fly zone avoidance effect judgment mechanism can effectively reduce the number of no-fly zone constraints and reduce the complexity of the problem.

[0120] Let δ be the angle between the current heading of the aircraft and the line connecting the center of the no-fly zone and the center of the aircraft, that is:

[0121] δ=ψ Ni -ψ(9)

[0122] Among them, ψ Ni Calculated by the following formula:

[0123]

[0124] In the formula, θ Ni and φ Ni are the longitude and latitude of the center point of the no-fly zone;

[0125] According to equations (9)-(10), the no-fly zone avoidance effect judgment mechanism is defined as:

[0126]

[0127] In the formula, when the value of P is 1, that is, the angle δ is greater than 90°, it means that there is still a risk of entering the no-fly zone, and the no-fly zone constraint needs to be continued to be considered; when the value of P is 0, that is, the angle δ is less than 90°, it means that the no-fly zone has been successfully avoided, and the no-fly zone constraint does not need to be considered, thereby simplifying the number of problem constraints.

[0128] Considering that frequent use of the no-fly zone avoidance judgment mechanism will reduce the computational efficiency of the method, the no-fly zone avoidance judgment startup conditions are set as follows: (1) the number of no-fly zones within a radius of 200 kilometers with the current position of the aircraft as the center is greater than 3; (2) the distance to the center of the nearest no-fly zone is less than 150 kilometers.

[0129] The no-fly zone avoidance judgment mechanism is used only when the two no-fly zone avoidance judgment activation conditions (1)-(2) are met.

[0130] Step 4: Set the dynamic adjustment strategy of the detection cycle and detection step length to improve the flexibility of antenna detection;

[0131] In the initial stage of re-entry flight, the distance to the target point is far, and it takes a long time to use small step integration for feeler detection feedback, that is, it takes a long time to obtain the roll angle command; if a fixed detection cycle is used, the feeler detection will be not flexible enough. When approaching the target point, the feeler is likely to miss the target area due to the long detection cycle. Therefore, the present invention proposes a dynamic adjustment strategy for the detection cycle and the detection step.

[0132] The distance from the target point at the start of reentry is d total , the aircraft starts to perform antenna detection guidance at time k. At this time, the distance between the aircraft and the starting point is d k , use the following formula to calculate the antenna detection period T d To make dynamic adjustments:

[0133]

[0134] Where mod(·) represents the floor function.

[0135] It can be seen from formula (12) that when the flight range of the aircraft is less than 1 / 3 of the total range, the detection cycle is reduced; when the flight range exceeds 1 / 3 of the total range, a fixed detection cycle is used, and the fixed detection cycle is 100 seconds.

[0136] Similarly, the integration step length dT for antenna detection I Adjust by the following formula:

[0137]

[0138] Similar to the above formula, when it is less than 1 / 3 of the total flight distance, a decreasing integral step size is adopted. When it exceeds 1 / 3 of the total flight distance, a fixed integral step size is adopted. By dynamically adjusting the roll angle amplitude, the feeler detection period and the integral step size when the feeler is generated, the feeler method is adapted to the re-entry guidance mission with complex no-fly zone avoidance problems, and the solution rate of the roll angle guidance command is improved.

[0139] Step 5: Define the termination conditions and scoring criteria for antenna generation, and prioritize the antenna with the smallest score as the guidance instruction scheme;

[0140] Step 5.1: According to the HGV reentry guidance characteristics, define the termination conditions for antenna generation as follows:

[0141] C1: The flight time of the aircraft exceeds the maximum flight time of the mission. Preferably, the maximum flight time is set to 3200 seconds according to empirical values ​​in the present invention;

[0142] C2: The antenna touches the edge of the no-fly zone or enters the no-fly zone;

[0143] C3: The calculated states of the tentacles at each moment exceed the maximum value of the path constraint;

[0144] C4: The heading angle deviation between the antenna tip and the target point exceeds the upper limit of 90°;

[0145] C5: antennal tips reach the terminal region;

[0146] Step 5.2: Record the scores of C1 to C5 corresponding to the termination conditions as the score matrix K a =[a1,a2,a3,a4,a5], if the antenna is terminated by condition Ci (i=1,2,3,4,5), then the score of the termination condition of this antenna is a i (i=1,2,3,4,5);

[0147] Step 5.3: Arrange the distances from the end of each tentacle to the target point in ascending order, and record the score of the i-th tentacle as k bi , the closer the distance, the higher the priority of the corresponding tentacles, and the smaller the score, so the final score of each tentacles is K i =k ai ·k bi , where k ai is the score of the termination condition of the i-th antenna, that is, the score matrix K a The value in ;

[0148] The goal of the reentry maneuver guidance problem considering no-fly zone avoidance is to seek a safe and accurate trajectory so that the aircraft can reach the target area according to the guidance instructions. Analysis of the above five termination conditions shows that the heat flux, dynamic pressure, and overload constraints are broken. Entering or touching the edge of the no-fly zone will threaten the safety of the aircraft and cause the flight mission to fail. Therefore, the tentacles terminated by these two conditions are the least suitable; and exceeding the heading angle deviation constraint will cause the aircraft to miss the target point and face the direction opposite to the target point. Therefore, the risk of mission failure caused by the tentacles stopped by termination condition C4 is slightly lower than that of C2 and C3; the tentacles stopped because the integral time exceeds the maximum mission time indicate that the tentacles are safe in the prediction process, and the risk of mission failure caused by such tentacles is slightly lower than that of C2, C3, and C4; since the tentacles terminated by condition C5 are required by the present invention, such tentacles should be selected first. Therefore, the relationship between the scores of the five termination conditions should satisfy:

[0149] a2=a3>a4>a1>a5>0 (14)

[0150] Based on the above principles, the matrix K set by the present invention a is [0.1, 1, 1, 0.6, 0.05], K a The value of can be adjusted, but it should satisfy formula (14); the distance priority scoring principle is k bi = 0.5 + 0.01 * i, the distance to the target point is arranged in ascending order, and the total score of the i-th antenna is K i =k ai ·k bi , then the antenna with the smallest score should be the optimal choice, and its corresponding roll angle is the guidance instruction within the guidance cycle.

[0151] Specifically, the antenna generation process in the present invention selects the 3-antenna method in the prior art, that is, generating -σ c |, 0, |σ c |The antennae corresponding to the three tilt angles, |σ c | is based on the state of the antenna generation moment, and is the maximum roll angle amplitude obtained to meet the roll angle range constraint in the second step. The guidance period is recorded as T guide ,According to the fourth step, the antenna detection period and the integration step are dynamically adjusted.,When handling multiple no-fly zone tasks, the no-fly zone avoidance effect judgment mechanism in the third step is continuously adopted to judge the no-fly zone avoidance situation, reduce the number of no-fly zone constraints, and improve the algorithm efficiency.

[0152] As a detection antenna generation method, step two uses the maximum roll angle amplitude that satisfies path constraints and quasi-balanced gliding conditions as the basis for antenna generation. Step four sets the detection cycle and detection step size dynamic adjustment strategy to improve the efficiency of antenna generation and the flexibility of detection.

[0153] As a no-fly zone avoidance method, step three proposes a no-fly zone avoidance judgment mechanism, which effectively solves the problem of too many constraints caused by a large number of no-fly zones; step five proposes the termination conditions and scoring criteria for the generation of tentacles according to the mission objectives of the reentry vehicle, including maximum time, path constraints, no-fly zone constraints, heading angle deviation upper limit and reaching the terminal area, and uses the scoring criteria to accurately judge the score of each tentacles. The calculation of the roll angle command solution is small and the solution is fast, which can quickly obtain accurate and effective guidance commands.

[0154] As a reentry guidance method, the present invention proposes a dynamic no-fly zone avoidance method taking no-fly zones into consideration. The principle is simple and only requires the calculation of the antenna state. Unlike the traditional common methods, which have certain requirements or approximate processing on the shape of the no-fly zone, the method does not make any requirements or approximate the shape of the no-fly zone. Therefore, the method can adapt to no-fly zone constraints of different shapes and numbers, dynamically adjust the period and integration step of antenna detection, and adaptively generate the roll angle amplitude of antenna detection, so as to quickly and safely avoid the no-fly zone.

[0155] Example

[0156] In order to verify the effect of the method proposed in the present invention, a simulation experiment is carried out according to the following steps.

[0157] Step 1: Set the simulation parameters and initial state settings of the hypersonic glide vehicle, as shown in Table 1.

[0158] Table 1 Reentry guidance simulation parameter settings

[0159]

[0160] Step 2: Conduct a single no-fly zone avoidance simulation experiment with different shapes to verify the effectiveness of the no-fly zone avoidance maneuvering guidance algorithm based on dynamic antennas proposed in this invention. Specifically, it includes two tasks, where Task 1 is a single circular no-fly zone with a center position of (40,0) degrees and a no-fly zone radius of 1 degree; Task 2 is a single rectangular no-fly zone with a starting point of (35,-1) degrees, a length of 35 degrees, and a width of 1.5 degrees.

[0161] Step 3: Conduct multiple no-fly zone avoidance simulation experiments to verify the feasibility of the present invention for multiple no-fly zone avoidance tasks. Set Task 3, in which 37 circular no-fly zones with centers evenly distributed on two semicircles and a radius of 0.5 degrees are set.

[0162] Step 4: Conduct a dynamic no-fly zone avoidance maneuver guidance simulation experiment and set Task 4, which is a linear motion no-fly zone avoidance experiment. In a circular no-fly zone with a radius of 0.5 degrees, the center position moves linearly from (30, 2) to (50, -2) with a period of 1500 seconds.

[0163] Figure 2 (a) and (b) show the changes in the longitude and latitude of the aircraft and the changes in the roll angle command during the maneuver guidance of Task 1. Due to the roll angle reentry corridor constraint, the roll angle amplitude of the antenna generated by the three-antenna method is constantly changing dynamically. When the aircraft travels for a period of time, the left and middle antennas of the three antennas in the direction of the aircraft touch the edge of the no-fly zone, and the right antenna detection terminal is closer to the target area. Therefore, the aircraft selects the roll angle command corresponding to the right antenna as the guidance command. The figure shows a trend of avoiding the no-fly zone, proving that the method proposed in the present invention can significantly avoid the no-fly zone.

[0164] Similarly, Figures 3 to 5 The simulation results of the no-fly zone avoidance maneuver guidance for tasks 2 to 4 are respectively presented. According to the simulation experimental results, it is proved that the complex no-fly zone avoidance reentry guidance method proposed in the present invention can achieve the expected complex no-fly zone avoidance reentry guidance effect.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A complex no-fly zone avoidance reentry guidance method based on dynamic antenna method, characterized in that: The following steps are involved: Step 1: For hypersonic glide vehicles, a model of the no-fly zone avoidance and reentry guidance problem for hypersonic glide vehicles is established; Step 2: Generate antennae using the three-antennae method, determine the roll angle reentry corridor, and obtain the roll angle amplitude when the antennae are generated; Step 3: Determine whether the current aircraft meets the no-fly zone avoidance judgment start conditions. If so, use the no-fly zone avoidance judgment mechanism to eliminate the no-fly zones that have been avoided and reduce the number of reentry guidance problem constraints; otherwise, go to step 4; Step 4: Use the dynamic adjustment strategy of the detection period and detection step length during antenna detection to adjust the detection period and integration step length; Step 5: Set the termination conditions for antenna generation and score them, and prioritize the antenna with the smallest score as the guidance instruction plan.

2. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 1, characterized in that: The specific steps of step 1 are: Step 1.1: Construct a three-degree-of-freedom reentry motion model of a hypersonic glide vehicle in a semi-velocity coordinate system: Where r represents the relative distance from the aircraft to the center of the earth; θ and φ are the current longitude and latitude respectively; V is the speed of the aircraft relative to the earth; γ and ψ are the flight path angle and heading angle respectively; L and D are lift and drag respectively; σ is the roll angle; m is the mass of the aircraft, and g is the gravitational acceleration of the earth; The calculation formulas for lift L and drag D are: Where ρ is the atmospheric density; R e is the average radius of the earth, e is a natural constant; S r is the reference cross-sectional area of ​​the aircraft; C L and C D They are lift coefficient and drag coefficient respectively: In the formula, l i is the lift coefficient; d i are the parameters of the drag coefficient fitting model; Step 1.2: Define the path constraints to be met during the HGV reentry flight: in, n, Refers to heat flow rate, overload and dynamic pressure respectively; K Q =7.9686×10 -5 represents the heat flow rate constant associated with the aircraft structure; n max , They refer to the maximum allowable values ​​of heat flow rate, overload and dynamic pressure respectively; Step 1.3: Define the quasi-equilibrium glide conditions that the HGV reentry flight must satisfy:

3. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 2, characterized in that: The specific steps of step 2 include: Step 2.1: Calculate the atmospheric density using the following formula: Where h = rR e ,h s is the atmospheric density correlation coefficient, R e is the average radius of the earth, e is a natural constant; Step 2.2: Based on the path constraint and the above formula, the height-speed constraint is obtained: Among them, r Q (V), r n (V), r q (V) are the heat fluxes in the path constraints. Dynamic Pressure Overload n to obtain the height constraint; Step 2.3: Based on the above formula, the quasi-balanced gliding condition defined in step 1.3 is combined to obtain the roll angle reentry corridor that satisfies the path constraint: r min (V)=max(r Q (V),r q (V),r n (V)) Where |σ(V)| max Indicates the maximum value of the roll angle; r min (V) represents the minimum altitude that satisfies the altitude-speed constraint and quasi-balanced gliding condition.

4. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 3, characterized in that: The specific steps of step 3 are as follows: Step 3.1: Define the angle between the current heading of the aircraft and the line connecting the center of the no-fly zone and the center of the aircraft as δ: d=ψ Ni -ψ in, In the formula, θ Ni and φ Ni are the longitude and latitude of the center point of the no-fly zone; Step 3.2: Based on δ, the no-fly zone avoidance effect judgment mechanism is obtained: Among them, when the value of P is 1, that is, the angle δ is greater than 90°, it means that there is still a risk of entering the no-fly zone and the no-fly zone constraints need to continue to be considered; when the value of P is 0, that is, the angle δ is less than 90°, it means that the no-fly zone has been successfully avoided and the no-fly zone constraints do not need to be considered.

5. The complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 1, characterized in that: The no-fly zone avoidance judgment start conditions described in step 3 include: Condition 1) The number of no-fly zones within a radius of 200 kilometers with the current position of the aircraft as the center is greater than 3; Condition 2) The distance to the nearest no-fly zone center is less than 150 kilometers.

6. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 4, characterized in that: The steps in step 4 include: Step 4.1: The antenna detection period T is calculated according to the following formula: d To make dynamic adjustments: Where mod(·) represents the floor function, d total Indicates the distance from the starting point to the target point, d k Indicates the distance of the aircraft relative to the starting point; Step 4.2: The integration step length dT during antenna detection is calculated by the following formula: I Make adjustments:

7. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 5, characterized in that: Step 5 includes the following steps: Step 5.1: Define the termination conditions for antenna generation; Step 5.2: The score matrix composed of the scores corresponding to each termination condition is recorded as K a =[a1,a2,a3,a4,a5], and a2=a3>a4>a1>a5>0; Step 5.3: Arrange the distances from the end of each tentacle to the target point in ascending order, and record the score of the i-th tentacle as k bi , the closer the distance, the higher the priority of the corresponding antenna, k bi The smaller the score k of the i-th antenna bi for: k bi =0.5+0.01*i; Step 5.4: Calculate the final score for each antenna using the following formula: K i =k ai ·k bi ; Among them, k ai is the score of the termination condition of the i-th antenna; Step 5.5: According to the score K i The antennae are sorted, and the roll angle corresponding to the antenna with the smallest score is used as the guidance instruction in the guidance cycle.

8. A complex no-fly zone avoidance reentry guidance method based on dynamic feeler method as claimed in claim 7, characterized in that: The termination conditions described in step 5.1 include: C1: The flight time of the aircraft exceeds the maximum flight time of the mission; C2: The antenna touches the edge of the no-fly zone or enters the no-fly zone; C3: The calculated states of the tentacles at each moment exceed the maximum value of the path constraint; C4: The heading angle deviation between the antenna tip and the target point exceeds the upper limit of 90°; C5: The antennae reach the terminal region.

9. A complex no-fly zone avoidance reentry guidance system, implemented based on the method described in any one of claims 1 to 8, characterized in that: The system includes the following modules: The model building module is used to build a model for the hypersonic glide vehicle's no-fly zone avoidance and reentry guidance problem; A roll angle amplitude calculation module is used to generate feelers using a three-feeler method, determine the roll angle reentry corridor, and obtain the roll angle amplitude when the feeler is generated; The no-fly zone avoidance judgment module is used to judge whether the current aircraft meets the no-fly zone avoidance judgment start conditions. If it does, the no-fly zone avoidance judgment mechanism is used to eliminate the no-fly zones that have been avoided, thereby reducing the number of constraints on the reentry guidance problem. A detection adjustment module, used to adjust the detection cycle and the integration step length by using a dynamic adjustment strategy of the detection cycle and the detection step length during antenna detection; The antenna generation module sets the termination conditions for antenna generation and scores them, giving priority to the antenna with the smallest score as the guidance instruction scheme.

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