Parawing flight path simulation method based on multi-rectangle homing
Through the parachute simulation method based on multi-rectangular return, the problem of inoperable parachutes and insufficient return capacity of traditional recycling systems is solved, and high-precision recycling and landing effects are achieved.
Patent Information
- Application Number
- CN202411831589.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-03-28
AI Technical Summary
The parachutes in the traditional recycling system cannot be manipulated, resulting in poor accuracy of the recycling site and the residency capacity of the existing parachutes is not enough to cover the entire landing area.
The wing parachute trajectory simulation method based on multi-rectangular reunification is adopted. By establishing the mathematical motion model of the wing parachute and the multi-rectangular reunification control model, the optimal target point and design reunification control law are determined, and simulation is carried out through simulation software to optimize the reunification trajectory of the wing parachute.
The best-effect parachute landing area control under different conditions is achieved, which improves the accuracy of the recovery site, reduces resource consumption, and improves landing accuracy.
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Figure CN119720564A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of spacecraft return and landing, and relates to a parafoil track simulation method based on multi-rectangle homing. Background Art
[0002] The traditional recovery system uses a ballistic parachute system. Once the parachute is opened, it can no longer be manipulated. The accuracy of the recovery location is mainly affected by the opening height and the wind in the landing area at that time, and the landing point accuracy is poor. The controllable wing parachute has excellent gliding performance and flight stability. It is manipulable and can be used for "bird landing". It is of great significance for the fixed-point landing of spacecraft, airdrop of various materials, and even long-term hovering gliding. The controllable wing parachute also has the advantages of being foldable and light in weight. It has broad application prospects in spacecraft return, drone recovery, and airdrop.
[0003] After the parafoil is opened and stabilized, its vertical and horizontal speed values also enter a relatively stable state, and the horizontal speed cannot be significantly increased. Therefore, when its homing ability is insufficient to cover the entire landing area, the homing method using a single fixed target point may make it difficult to reach the predetermined target landing area. Therefore, it is necessary to design a multi-rectangular target homing control algorithm according to the scattered characteristic range of the landing area and perform track simulation analysis on the homing control algorithm to determine the effectiveness of the algorithm. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a parafoil trajectory simulation method based on multi-rectangular homing, so as to achieve the best parafoil homing landing area control under different conditions.
[0005] The present invention provides the following technical solutions:
[0006] A parafoil trajectory simulation method based on multi-rectangular homing includes the following steps:
[0007] (1) Establishing a mathematical model of the parafoil motion, including a turning motion model and a linear motion model of the parafoil;
[0008] (2) Establish a multi-rectangular homing control model for the parafoil, including: determining the optimal target point and designing the homing control law;
[0009] (3) Determine typical flight input and output data parameters and typical operating conditions;
[0010] (4) According to the motion mathematical model of the parafoil established in step (1), the multi-rectangular homing control model of the parafoil established in step (2), and the typical flight input and output data parameters and typical working conditions determined in step (3), simulation software is designed and simulation is performed to obtain the motion trajectory of the parafoil.
[0011] Furthermore, the turning motion model of the parafoil is specifically:
[0012] In the case of a parafoil turning motion, the position and velocity after each time period τ are calculated according to the following recursive formulas (1) to (7):
[0013]
[0014] Wx=-Wsinβ; (5)
[0015] Wy=-Wcosβ; (6)
[0016]
[0017] Among them, when turning left, a=1; if turning right, a=-1; r is the turning radius; V is the horizontal speed; β is the wind direction angle; θ is the arc angle turned within τ time; W x , W y is an intermediate variable; W is the wind vector at a certain altitude.
[0018] At any time, the projection coordinates of the subsatellite point of the center of mass of the parafoil system in the ground coordinate system Oxy are x, y, and the projection of the velocity vector on the x-axis is V x , the projection on the y-axis is V y ; x', y', V x ′ 、V y ′ Corresponding to x, y, V respectively x 、V y The value after a time interval of τ.
[0019] Furthermore, the linear motion model of the parafoil is specifically:
[0020] When the heading deviation angle γ of the parafoil system is within the blind angle range, that is, -γ0≤γ≤γ0, the parafoil system flies in a straight line relative to the still air; at this time, assuming that the linear motion of the parafoil is greater than the horizontal speed of the turning motion by ΔV, its flight state is calculated using recursive formulas (8) to (12);
[0021] x ′ =x+(V x -ΔVcosΦ+W x ) τ (8)
[0022] y ′ =y+(V y +ΔVsinΦ+W y ) τ (9)
[0023] V x ′ =Vx (10)
[0024] V y ′ =V y (11)
[0025] ΔV=V * -V (12)
[0026] Among them, V * is the horizontal velocity of the parafoil system in linear motion; V is the horizontal velocity of the parafoil system in turning motion; ΔV is the difference between the horizontal velocities in linear motion and turning motion; Φ is the angle between the horizontal velocity V and the negative direction of the Ox axis, 0<Φ≤2π.
[0027] Furthermore, the optimal target point is determined, including:
[0028] Set N target rectangles in the landing area, and set M target points inside the N target rectangles;
[0029] When it is determined that the real-time position of the parafoil is outside all rectangles, the parafoil is controlled to fly toward the nearest target rectangular border or end point;
[0030] When it is determined that the real-time position of the parafoil is located inside a certain rectangle, the parafoil is controlled to fly toward the nearest target point inside the rectangle, and the nearest target point is the optimal target point.
[0031] Furthermore, the parafoil landing area is a rectangular area, three target lines are selected in the rectangular landing area, multiple landing points are selected in the target lines, and multiple obstacle avoidance points are selected in the landing area;
[0032] The landing area is 90km×30km in size;
[0033] The double target line is rectangular, 2.8km wide by 86km long;
[0034] The boundary rectangle of the landing area is 1km×30km in size.
[0035] The expected landing area of the parafoil is three long rectangular target areas including a double target line rectangle and a landing area boundary rectangle, which are recorded as line target rectangles 1, 2, and 3 respectively.
[0036] Furthermore, the landing area is divided into four areas according to the landing area range, area 1 to area 4;
[0037] Area 1 is outside the line target rectangles 1, 2, and 3. When the parafoil projection point is in area 1, the parafoil is controlled to fly toward the boundary of the line target rectangles 1, 2, and 3. The intersection of the parafoil point and the foot of the outer frame of the line target rectangle or the border endpoint closest to the parafoil point is selected as the optimal target point.
[0038] Area 2 is inside the line target rectangle 1. When the parafoil projection point is inside area 2, the parafoil is controlled to fly to the target point Rectangle1_Point1~N in the line target rectangle 1, and the point closest to the parafoil point among the target points Rectangle1_Point1~N is taken as the optimal target point;
[0039] Area 3 is inside the line target rectangle 2. When the parafoil projection point is inside area 3, the parafoil is controlled to fly to the target point Rectangle2_Point1~N in the line target rectangle 2, and the point closest to the parafoil point among the target points Rectangle2_Point1~N is taken as the optimal target point;
[0040] Area 4 is inside the line target rectangle 3. When the parafoil projection point is inside area 4, the parafoil is controlled to fly to the target point Rectangle3_Point1~N in the line target rectangle 3, and the point closest to the parafoil point among the target points Rectangle3_Point1~N is taken as the optimal target point.
[0041] Furthermore, the designed homing control law is specifically as follows:
[0042] The homing trajectory design of the parafoil system is divided into five stages: parafoil stabilization stage, directional homing stage, flying around the pin height stage, headwind landing stage, and bird landing stage.
[0043] Parafoil stabilization phase: issue a series of recovery control commands to pull out the parachute and parafoil, and wait for the parafoil to be stably opened before implementing homing control;
[0044] Directional return stage: control the parafoil flight direction to point to the direction of the target point connection line. When the parafoil is far away from the target point, that is, the distance D between the parafoil and the target point is greater than 300 meters, make the parafoil approach the target point in a straight line; when entering the range of 300 meters from the target point, the parafoil controller calculates the remaining flight distance Dr; when the remaining flight distance Dr is greater than the circumvention distance Dc, enter the circumvention pin high stage; when the remaining flight distance Dr is less than or equal to the circumvention distance Dc, directly adjust to the headwind landing stage and land;
[0045] The flying method of the high section around the flying pin is to rotate around the target point, and the flying method of the upwind landing section is to adjust the position and direction to align with the incoming wind direction and wait for landing;
[0046] The canopy landing phase is when the remaining height is less than 20 meters, the bilateral control amounts are quickly pulled down to the maximum value at the same time, so that the horizontal and vertical speeds of the parafoil are reduced to the minimum value.
[0047] Furthermore, the remaining flight mileage is calculated as follows: Dr = Hr*Fs, where Dr is the remaining flight mileage, Hr is the remaining altitude, and Fs is the instantaneous glide ratio;
[0048] The calculation formula for the circling distance Dc is: Dc=Rc+2π*Rc; where Rc is the circling radius, the initial value is 100m, and then during the circling process it will be calibrated by the actual circling radius collected by the homing computer.
[0049] Furthermore, the determination of typical flight input and output data parameters is specifically as follows:
[0050] Typical flight input parameters include: initial state of the parafoil, state of the target point and weather conditions;
[0051] The output data parameters include: parafoil trajectory data, parafoil speed data, parafoil three-axis attitude data, control amount data and homing status.
[0052] Furthermore, the typical working conditions are determined, including typical wind speed and direction working conditions and simulation test working conditions;
[0053] Typical wind speed and direction conditions are: no wind, wind speed of 3m / s, 5m / s, 7m / s; when the wind speed is 3m / s, 5m / s, 7m / s, the design wind direction is 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315° respectively;
[0054] The simulation test conditions are as follows:
[0055]
[0056] where Fs is the instantaneous glide ratio.
[0057] Furthermore, the simulation software includes an initial parameter generator, a multi-rectangular homing algorithm calculation module, and a parafoil motion model module;
[0058] The initial parameter generator inputs the typical flight input parameters to the multi-rectangular homing algorithm calculation module. The multi-rectangular homing algorithm calculation module determines the optimal target point and homing control law according to the initial state of the parafoil and the target point state, and then calculates and generates the parafoil motion trajectory according to the parafoil motion mathematical model in the parafoil motion model module, and feeds back the output data parameters to the multi-rectangular homing algorithm calculation module for iterative calculation to update the parafoil motion trajectory.
[0059] Compared with the prior art, the present invention has the following beneficial effects:
[0060] (1) The method of the present invention is directed to a parafoil trajectory simulation method based on multi-rectangular homing, and the effectiveness and accuracy of the parafoil multi-rectangular homing algorithm are verified through simulation.
[0061] (2) The method of the present invention can further modify the algorithm through simulation results. Through repeated iterations of algorithm design and simulation verification, the optimal algorithm and parameter design for the wing parafoil multi-rectangular homing are finally determined. BRIEF DESCRIPTION OF THE DRAWINGS
[0062] Figure 1 This is the left turn flight relationship diagram;
[0063] Figure 2 This is the relationship diagram for right turn flight;
[0064] Figure 3 It is a straight line flight relationship diagram;
[0065] Figure 4 This is a schematic diagram of the rectangular division of the landing area;
[0066] Figure 5 This is a schematic diagram of the linear homing landing area;
[0067] Figure 6 This is the homing schematic diagram of linear homing area 1;
[0068] Figure 7 This is a schematic diagram of homing in linear homing areas 2, 3, and 4;
[0069] Figure 8 This is a schematic diagram of the homing process;
[0070] Fig. 9 This is the parafoil return trajectory diagram;
[0071] Fig.10 It is a schematic diagram of the phase conversion relationship;
[0072] Fig.11 Schematic diagram of multi-rectangle homing control simulation software design. DETAILED DESCRIPTION
[0073] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.
[0074] The homing ability and control accuracy of the parafoil are within a certain range, so the control range is also limited. For different landing areas and homing capabilities, the landing point needs to be planned to achieve the best dispersion control. The use of multi-rectangular homing can make full use of the parafoil's flight ability, effectively reduce the dispersion area of the parafoil's recyclables, and reduce resource consumption. When the parafoil's flight ability can only reach the edge of the rectangle, the directional homing mode is adopted, and the parafoil flies straight to the nearest rectangular boundary; when the parafoil's flight ability still has a margin after flying across the rectangular boundary, it continues to fly to the scattered landing points inside the rectangle to further shrink the landing area; when the parafoil's flight ability still has a margin within the landing radius of the scattered target point, it will enter the circling pin height and final landing and bird landing mode to further improve the landing accuracy. In this way, the parafoil landing area can be shrunk in multiple levels according to its different flight capabilities, so as to achieve a more flexible and optimal landing area control effect under different conditions.
[0075] After the parafoil homing control algorithm is determined, simulation verification is needed to verify the effectiveness and accuracy of the algorithm. And the algorithm needs to be further modified through simulation results. Through repeated iterations of algorithm design -> simulation verification, the optimal algorithm and parameter design are finally determined.
[0076] The present invention proposes a parafoil trajectory simulation method based on multi-rectangular homing, comprising the following steps:
[0077] (1) Establishing a mathematical model of the parafoil motion, including a turning motion model and a linear motion model of the parafoil;
[0078] (2) Establish a multi-rectangular homing control model for the parafoil, including: determining the optimal target point and designing the homing control law;
[0079] (3) Determine typical flight input and output data parameters and typical operating conditions;
[0080] (4) According to the motion mathematical model of the parafoil established in step (1), the multi-rectangular homing control model of the parafoil established in step (2), and the typical flight input and output data parameters and typical working conditions determined in step (3), simulation software is designed and simulation is performed to obtain the motion trajectory of the parafoil.
[0081] A detailed introduction is given below.
[0082] 1. Design and implementation of parafoil sports model
[0083] There are four basic motion forms of the parafoil system in the control process: gliding, turning, deceleration and bird landing. Bird landing is only implemented in the final landing stage, and this process is not included in the scope of trajectory planning. Compared with gliding motion, the deceleration motion of the bilateral downward deflection has little effect on the flight trajectory, so gliding and turning operations are mainly implemented in the trajectory simulation.
[0084] First, the following basic assumptions are made: the control is completed instantaneously (referring to tightening and loosening the control rope); the parafoil canopy rotates synchronously with its payload; and the wind is assumed to be a constant vector for each calculated altitude. This simulation calculation uses the ground coordinate system Oxy, which is a coordinate system fixed to the earth. Taking the parafoil single-point homing target point O as the origin, the Ox axis points to the east and the Oy axis points to the north. Taking into account the trend of wind changes with altitude and the impact of altitude changes on the speed of the parafoil system, the calculation is performed in layers according to altitude, and the speed and wind field can be considered to be constant in each layer. At any moment, the projection coordinates of the sub-satellite point of the center of mass of the parafoil system in the coordinate system Oxy are x and y, and the projection of the velocity vector on the x-axis is V x , the projection on the y-axis is V y ;
[0085] x', y', vx', vy' are the values of x, y, vx, vy after a time interval of τ.
[0086] Parafoil turning motion model:
[0087] In the case of a parafoil turning motion, the position and velocity after each time period τ can be calculated using the following recursive formulas (1) to (7). The angle relationship of the turning flight is shown in Figure 1 and Figure 2 When turning left, a=1; if turning right, a=-1.
[0088]
[0089] Wx=-Wsinβ; (5)
[0090] Wy=-Wcosβ; (6)
[0091]
[0092] r——turning radius;
[0093] V——horizontal speed;
[0094] β——wind direction angle;
[0095] θ——the arc angle turned in τ time. W is the wind vector.
[0096] Parafoil linear motion model:
[0097] When the heading deviation angle of the parafoil system is within the blind angle range, that is, -γ0≤γ≤γ0, the system flies in a straight line relative to the still air. At this time, assuming that the horizontal speed of the parafoil's linear motion is ΔV greater than that of its turning motion, its flight state can be calculated using the recursive formulas (8) to (12). When the parafoil is flying in a straight line, its flight relationship is shown in Figure 3 shown.
[0098] V * ——Horizontal speed of the parafoil system in the case of linear motion;
[0099] V——horizontal speed of the parafoil system in turning motion;
[0100] ΔV – the difference between horizontal speed during straight line motion and horizontal speed during turning motion;
[0101] Φ——The negative angle between the horizontal velocity V and the Ox axis, 0<Φ≤2π.
[0102] x ′ =x+(V x -ΔVcosΦ+W x ) τ (8)
[0103] y ′ =y+(V y +ΔVsinΦ+W y ) τ (9)
[0104] V x ′ =V x (10)
[0105] V y ′ =V y (11)
[0106] ΔV=V * -V (12)
[0107] 2. Design and implementation method of multi-rectangle homing algorithm model
[0108] 2.1 Optimal target point design
[0109] The algorithm for the multi-rectangle homing flight of the parafoil is as follows: N target rectangles are set in the landing area, and M target points are set inside the N target rectangles. When it is determined that the real-time position of the parafoil is outside all rectangles, the parafoil is controlled to fly toward the nearest target rectangle border or endpoint. When it is determined that the real-time position of the parafoil is inside a certain rectangle, the parafoil is controlled to fly toward the nearest target point inside the rectangle. The specific algorithm is illustrated by the following example: suppose the landing area of the parafoil is a rectangular area, three target lines are selected in the rectangular landing area, multiple landing points are selected within the target lines, and multiple obstacle avoidance points are selected within the landing area. The schematic diagram of the landing area is as follows Figure 5 As shown. The green square mark is the landing zone boundary mark, rectangle 0 is the landing zone boundary, and the size is 90km×30km. Rectangles 1 and 2 are double target line rectangular boundaries, 2.8km wide and 86km long. Rectangle 3 is the landing zone boundary rectangle, and the size is 1km×30km. Figure 4 As shown in the figure, the overall assessment of the landing point of the booster parachute subsystem is to land in three long rectangular target areas 1, 2, and 3, so the homing control strategy is to ensure that the subsystem must land in the three designated long rectangular target areas.
[0110] The landing area is divided into four areas by the landing area boundaries, see Figure 6 Round yellow mark. Area 1 is outside of line targets 1, 2, and 3. When the parafoil projection point is in area 1, control the parafoil to fly to the boundary of line targets 1, 2, and 3. Select the intersection of the parafoil point and the outer frame of the line target or the end point of the frame (select the point closer to the parafoil point) as the optimal target point, see Figure 5 .
[0111] Area 2 is inside the line target 1. When the parafoil projection point is inside area 2, the parafoil is controlled to fly to the target point Rectangle1_Point1~N inside the line target 1 (see Figure 7 The point closest to the parafoil point among the target points Rectangle1_Point1~N is selected as the optimal target point.
[0112] Area 3 is inside the line target 2. When the parafoil projection point is inside area 3, the parafoil is controlled to fly to the target point Rectangle2_Point1~N inside the line target 2 (see Figure 7 The point closest to the parafoil point among the target points Rectangle2_Point1~N is selected as the optimal target point.
[0113] Area 4 is inside the line target 3. When the parafoil projection point is inside area 4, the parafoil is controlled to fly to the target point Rectangle3_Point1~N inside the line target 3 (see Figure 7Red circle mark). Take the point in Rectangle3_Point1~N that is closer to the parafoil point as the optimal target point. See the schematic diagram of homing in area 2, 3, and 4 for details. Figure 7 .
[0114] 2.2 Design of homing control law
[0115] The parafoil system adopts a multi-mode, phased homing control law and a dual-antenna GPS measurement system. It uses the real-time position, speed and heading information and the pre-set target point position to calculate and determine the system's working mode and corresponding working stage in real time, and take corresponding operating steps to achieve the homing of the parafoil system. The homing trajectory design of the parafoil system is divided into five stages: parafoil stability stage, directional homing stage, flying around the pin height stage, headwind landing stage, and bird landing stage. See the flight process Figure 8 .
[0116] The main work of the wing parachute stabilization stage is to issue a series of recovery control instructions to pull out the deceleration parachute and the wing parachute, and wait for the wing parachute to be stably opened before implementing the homing control. The main working process of the directional homing stage is to manipulate the wing parachute's flight direction to point to the direction of the target point connection line, so that the wing parachute approaches the target point in a straight line. When the wing parachute is far away from the target point (the distance D between the wing parachute and the target point is greater than 300 meters), the directional homing algorithm is adopted. When entering within 300 meters of the target point, the wing parachute controller calculates the remaining flight mileage Dr (Dr = Hr * Fs, where Dr is the remaining flight mileage, Hr is the remaining height, and Fs is the instantaneous glide ratio). When the remaining flight mileage Dr is greater than the circumnavigation mileage Dc, it enters the circumnavigation stage. When the remaining flight mileage is less than or equal to the circumnavigation mileage, it is directly adjusted to the upwind landing stage and landed. The flight mode in the circumnavigation stage is to rotate around the target point. The flight mode in the upwind landing stage is to adjust to the position and direction aligned with the incoming wind direction and wait for landing. The bird landing phase is when the remaining height is less than 20 meters, the bilateral control values are quickly pulled down to the maximum value at the same time, so that the horizontal and vertical speeds of the parafoil are reduced to the minimum value. The homing trajectory of each stage is as follows Fig. 9 The phase transition relationship is shown in Fig.10 The control method of each stage is shown in the following table.
[0117] The calculation method of remaining flight mileage Dr is:
[0118] Dr=Hr*Fs
[0119] Among them, Hr is the residual height, Fs is the instantaneous glide ratio;
[0120] The calculation formula for the detour mileage Dc is:
[0121] Dc=Rc+2π*Rc.
[0122] Rc is the orbiting radius, with an initial value of 100m. It will then be calibrated using the actual orbiting radius collected by the homing computer during the orbiting process.
[0123] Table 1 Description of work at each stage
[0124]
[0125] Note: R - the distance between the parafoil ground projection and the scheduled landing point; Hr - the remaining height of the parafoil system; Dr - the remaining flight distance; Dc - the circumnavigation distance.
[0126] 3. Design and implementation method of initial parameter generator
[0127] 3.1 Typical flight input and output data parameters:
[0128] Typical flight input and output parameters are shown in the following table.
[0129] Table 2 Typical flight input parameters
[0130]
[0131] Table 3 Flight output key data
[0132]
[0133]
[0134] 3.2 Typical working condition design
[0135] The simulation verification needs to be divided into two conditions: no wind and wind. And multiple wind directions and wind force combinations are simulated. The typical working condition design is shown in the following table.
[0136] Table 4 Typical wind speed and direction working condition design table
[0137]
[0138] The simulation verifies the working conditions of the parafoil at different heights, distances, glide ratios, and relative positions between the entry point and the target point. The typical working condition design is shown in the following table.
[0139] Table 5 Simulation test condition design
[0140]
[0141] Among them, Fs is the instantaneous glide ratio; Dr is the distance between the parafoil and the target point (remaining flight distance); Hr is the height of the parafoil from the target point (remaining height).
[0142] 4. Simulation Software Design and Implementation Method
[0143] The wing parafoil multi-rectangle homing simulation software consists of an initial parameter generator, a multi-rectangle homing algorithm module and a wing parafoil motion model. The composition of the wing parafoil multi-rectangle simulation software is shown below: Fig.11 As shown. The design of the initial parameter generator is shown in Section 3. The design of the multi-rectangular homing algorithm model is shown in Section 2. The design of the parafoil motion model is shown in Section 1. The simulation software includes an initial parameter generator, a multi-rectangular homing algorithm calculation module, and a parafoil motion model module;
[0144] The initial parameter generator inputs the typical flight input parameters to the multi-rectangular homing algorithm calculation module. The multi-rectangular homing algorithm calculation module determines the optimal target point and homing control law according to the initial state of the parafoil and the target point state, and then calculates and generates the parafoil motion trajectory according to the parafoil motion mathematical model in the parafoil motion model module, and feeds back the output data parameters to the multi-rectangular homing algorithm calculation module for iterative calculation to update the parafoil motion trajectory.
[0145] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.
[0146] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.
Claims
1. A parafoil trajectory simulation method based on multi-rectangular homing, characterized in that: include: (1) Establishing a mathematical model of the parafoil motion, including a turning motion model and a linear motion model of the parafoil; (2) Establish a multi-rectangular homing control model for the parafoil, including: determining the optimal target point and designing the homing control law; (3) Determine typical flight input and output data parameters and typical operating conditions; (4) According to the motion mathematical model of the parafoil established in step (1), the multi-rectangular homing control model of the parafoil established in step (2), and the typical flight input and output data parameters and typical working conditions determined in step (3), simulation software is designed and simulation is performed to obtain the motion trajectory of the parafoil.
2. A parafoil trajectory simulation method based on multi-rectangular homing according to claim 1, characterized in that: The turning motion model of the parafoil is specifically: In the case of a parafoil turning motion, the position and velocity after each time period τ are calculated according to the following recursive formulas (1) to (7): Wx=-Wsinβ; (5) Wy=-Wcosβ; (6) Among them, when turning left, a=1; if turning right, a=-1; r is the turning radius; V is the horizontal speed; β is the wind direction angle; θ is the arc angle turned within τ time; W x , W y is the intermediate variable; W is the wind vector; At any time, the projection coordinates of the subsatellite point of the center of mass of the parafoil system in the ground coordinate system Oxy are x, y, and the projection of the velocity vector on the x-axis is V x , the projection on the y-axis is V y ; x', y', V x ′ 、V y ′ Corresponding to x, y, V respectively x 、V y The value after a time interval of τ.
3. A parafoil trajectory simulation method based on multi-rectangular homing according to claim 2, characterized in that: The linear motion model of the parafoil is specifically: When the heading deviation angle γ of the parafoil system is within the blind angle range, that is, -γ0≤γ≤γ0, the parafoil system flies in a straight line relative to the still air; at this time, assuming that the linear motion of the parafoil is greater than the horizontal speed of the turning motion by ΔV, its flight state is calculated using recursive formulas (8) to (12); x ′ =x+(V x -ΔVcosΦ+W x ) t (8) and ′ =y+(V y +ΔVsinΦ+W y ) τ (9) V x ′ =V x (10) V y ′ =V y (11) ΔV=V * -V (12) Among them, V * is the horizontal velocity of the parafoil system in linear motion; V is the horizontal velocity of the parafoil system in turning motion; ΔV is the difference between the horizontal velocities in linear motion and turning motion; Φ is the angle between the horizontal velocity V and the negative direction of the Ox axis, 0<Φ≤2π.
4. The parafoil trajectory simulation method based on multi-rectangle homing according to claim 1, characterized in that: Determine the optimal target point, including: Set N target rectangles in the landing area, and set M target points inside the N target rectangles; When it is determined that the real-time position of the parafoil is outside all rectangles, the parafoil is controlled to fly toward the nearest target rectangular border or end point; When it is determined that the real-time position of the parafoil is located inside a certain rectangle, the parafoil is controlled to fly toward the nearest target point inside the rectangle, and the nearest target point is the optimal target point.
5. The parafoil trajectory simulation method based on multi-rectangle homing according to claim 4, characterized in that: The parafoil landing area is a rectangular area. Three target lines are selected in the rectangular landing area, multiple landing points are selected within the target lines, and multiple obstacle avoidance points are selected within the landing area. The landing area is 90km×30km in size; The double target line is rectangular, 2.8km wide by 86km long; The boundary rectangle of the landing area is 1km×30km in size. The expected landing area of the parafoil is three long rectangular target areas including a double target line rectangle and a landing area boundary rectangle, which are recorded as line target rectangles 1, 2, and 3 respectively.
6. A parafoil trajectory simulation method based on multi-rectangular homing according to claim 5, characterized in that: The landing area is divided into four areas according to the landing area range, area 1 to area 4; Area 1 is outside the line target rectangles 1, 2, and 3. When the parafoil projection point is in area 1, the parafoil is controlled to fly toward the boundary of the line target rectangles 1, 2, and 3. The intersection of the parafoil point and the foot of the outer frame of the line target rectangle or the border endpoint closest to the parafoil point is selected as the optimal target point. Area 2 is inside the line target rectangle 1. When the parafoil projection point is inside area 2, the parafoil is controlled to fly to the target point Rectangle1_Point1~N in the line target rectangle 1, and the point closest to the parafoil point among the target points Rectangle1_Point1~N is taken as the optimal target point; Area 3 is inside the line target rectangle 2. When the parafoil projection point is inside area 3, the parafoil is controlled to fly to the target point Rectangle2_Point1~N in the line target rectangle 2, and the point closest to the parafoil point among the target points Rectangle2_Point1~N is taken as the optimal target point; Area 4 is inside the line target rectangle 3. When the parafoil projection point is inside area 4, the parafoil is controlled to fly to the target point Rectangle3_Point1~N in the line target rectangle 3, and the point closest to the parafoil point among the target points Rectangle3_Point1~N is taken as the optimal target point.
7. A parafoil trajectory simulation method based on multi-rectangular homing according to claim 6, characterized in that: The designed homing control law is specifically: The homing trajectory design of the parafoil system is divided into five stages: parafoil stabilization stage, directional homing stage, flying around the pin height stage, headwind landing stage, and bird landing stage. Parafoil stabilization phase: issue a series of recovery control commands to pull out the parachute and parafoil, and wait for the parafoil to be stably opened before implementing homing control; Directional return stage: control the parafoil flight direction to point to the direction of the target point connection line. When the parafoil is far away from the target point, that is, the distance D between the parafoil and the target point is greater than 300 meters, make the parafoil approach the target point in a straight line; when entering the range of 300 meters from the target point, the parafoil controller calculates the remaining flight distance Dr; when the remaining flight distance Dr is greater than the circumvention distance Dc, enter the circumvention pin high stage; when the remaining flight distance Dr is less than or equal to the circumvention distance Dc, directly adjust to the headwind landing stage and land; The flying method of the high section around the flying pin is to rotate around the target point, and the flying method of the upwind landing section is to adjust the position and direction to align with the incoming wind direction and wait for landing; The canopy landing phase is when the remaining height is less than 20 meters, the bilateral control amounts are quickly pulled down to the maximum value at the same time, so that the horizontal and vertical speeds of the parafoil are reduced to the minimum value.
8. The parafoil trajectory simulation method based on multi-rectangle homing according to claim 7, characterized in that: The calculation formula for the remaining flight mileage is: Dr = Hr * Fs, where Dr is the remaining flight mileage, Hr is the remaining altitude, and Fs is the instantaneous glide ratio; The calculation formula for the circling distance Dc is: Dc=Rc+2π*Rc; where Rc is the circling radius, the initial value is 100m, and then during the circling process it will be calibrated by the actual circling radius collected by the homing computer.
9. The parafoil trajectory simulation method based on multi-rectangle homing according to claim 1, characterized in that: The determination of typical flight input and output data parameters is specifically as follows: Typical flight input parameters include: initial state of the parafoil, state of the target point and weather conditions; The output data parameters include: parafoil trajectory data, parafoil speed data, parafoil three-axis attitude data, control amount data and homing status.
10. The parafoil trajectory simulation method based on multi-rectangular homing according to claim 9, characterized in that: The typical working conditions are determined, including typical wind speed and direction working conditions and simulation test working conditions; Typical wind speed and direction conditions are: no wind, wind speed of 3m / s, 5m / s, 7m / s; when the wind speed is 3m / s, 5m / s, 7m / s, the design wind direction is 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315° respectively; The simulation test conditions are as follows: where Fs is the instantaneous glide ratio.
11. The parafoil trajectory simulation method based on multi-rectangle homing according to claim 1, characterized in that: The simulation software includes an initial parameter generator, a multi-rectangular homing algorithm calculation module, and a parafoil motion model module; The initial parameter generator inputs the typical flight input parameters to the multi-rectangular homing algorithm calculation module. The multi-rectangular homing algorithm calculation module determines the optimal target point and homing control law according to the initial state of the parafoil and the target point state, and then calculates and generates the parafoil motion trajectory according to the parafoil motion mathematical model in the parafoil motion model module, and feeds back the output data parameters to the multi-rectangular homing algorithm calculation module for iterative calculation to update the parafoil motion trajectory.