Parawing homing path real-time correction method and system

Abstract

The invention provides a parafoil homing path real-time correction method and system. The parafoil homing path real-time correction method comprises the steps that the position and the free attitude angle of a parafoil system in a geodetic inertial coordinate system with a target point on the ground as the original point are obtained; according to the position and the free attitude angle, simulating a motion track and a track tail end position of the parafoil system in # imgabs0 # time by using a parafoil six-degree-of-freedom kinetic model; a positioning system is used for obtaining the motion trail and the trail tail end position of the parafoil system in the real wind field environment within the # imgabs1 # time; performing deviation analysis according to the simulated motion track and the track end position and the real motion track and the track end position to obtain a wind field estimation result; and correcting a parafoil homing path in real time by using a three-section homing method according to the wind field estimation result. According to the method, on the basis of a parafoil system differential dynamic model, a rolling optimization strategy is combined, and correction identification can be carried out on a surrounding wind field in a parafoil unsteady-state flight state.

Description

Technical Field

[0001] The present invention relates to the technical field of parafoil homing, and in particular to a method and system for real-time correction of a parafoil homing path. Background Art

[0002] The parafoil system has become a research hotspot for new airdrop systems due to its advantages of light weight, small size and controllability. However, it also has research difficulties such as weak controllability, complex modeling and susceptibility to wind field influence. The parafoil system must go through deployment, system identification, approaching the target, energy consumption, terminal search and landing stages during the homing process. During the energy management and descent stages, the wind field has a great influence on the parafoil flight trajectory. The effect of the wind field may cause the parafoil to become unstable or move away from the target point. For this reason, it is necessary to consider the wind field conditions at the real-time position when designing the parafoil homing trajectory. During the entire homing process, it is necessary to consider the wind field shear conditions at different altitudes and the differences in high and low wind fields. However, most existing methods cannot accurately estimate the wind field in real time, resulting in large deviations in the homing of the parafoil. Summary of the invention

[0003] The present invention provides a method and system for real-time correction of a parafoil homing path, which are used to overcome the defects of the prior art such as large parafoil homing deviation.

[0004] To achieve the above object, the present invention proposes a real-time correction method for a parafoil homing path, comprising the following steps: Obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; According to the position and free attitude angle, the parafoil system is simulated by using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; Using the positioning system to obtain The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, deviation analysis is performed to obtain the wind field estimation result; According to the wind field estimation result, the parafoil homing path is corrected in real time using the three-segment homing method.

[0005] To achieve the above object, the present invention further proposes a real-time correction system for a parafoil homing path, comprising: The information acquisition module is used to obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; the positioning system is used to obtain The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; The simulation module is used to simulate the parafoil system in the state of the parafoil according to the position and the free attitude angle using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; The wind field estimation module is used to perform deviation analysis based on the simulated motion trajectory and trajectory end position and the real motion trajectory and trajectory end position to obtain the wind field estimation result; The path correction module is used to correct the parafoil homing path in real time using the three-segment homing method according to the wind field estimation result.

[0006] To achieve the above-mentioned purpose, the present invention also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the above-mentioned method for real-time correction of the homing path of a parafoil are implemented.

[0007] To achieve the above object, the present invention further proposes a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the above-mentioned method for real-time correction of the homing path of a parafoil are implemented.

[0008] Compared with the prior art, the present invention has the following beneficial effects: Traditional parafoil flight wind field identification technology is usually based on the premise of the steady-state flight state of the parafoil, based on the condition that the parafoil flight speed is consistent with the wind direction, and the surrounding identification is performed through the least squares method, which is only suitable for flight conditions with constant wind fields or slowly changing wind fields; while the real-time correction method for the parafoil homing path provided by the present invention, based on the differential dynamics model of the parafoil system, combined with the strategy of rolling optimization, can correct and identify the surrounding wind field in the state of non-steady-state flight of the parafoil. Therefore, the present invention is not limited by the flight state of the parafoil system, and can perform real-time identification and correction of the surrounding wind field during the entire process of the parafoil system flight in the non-steady-state situation where the flight direction is inconsistent with the wind field direction, meeting the actual needs of the parafoil airdrop system under complex and changeable wind fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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 the structures shown in these drawings without paying creative work.

[0010] Figure 1 A flow chart of a real-time correction method for a parafoil homing path provided by the present invention; Figure 2 It is a schematic diagram of the single body model of the parafoil system; Figure 3 The wind field identification principle of the parafoil direct flight process; Figure 4 The wind field identification principle of the parafoil turning process; Figure 5 This is a schematic diagram of the three-stage homing method; Figure 6 This is the x-axis wind field identification result of the parafoil system in direct flight state; Figure 7 This is the y-axis wind field identification result of the parafoil system in direct flight state; Figure 8 It is the x-axis wind field identification result of the parafoil system in turning state; Fig. 9 It is the y-axis wind field identification result of the parafoil system in turning state; Fig.10 These are the three-segment homing simulation trajectories of the parafoil; a is the three-dimensional trajectory and b is the horizontal plane projection trajectory.

[0011] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0012] 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.

[0013] The present invention proposes a real-time correction method for a parafoil homing path, such as Figure 1 As shown, the following steps are included: 101: Obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; 102: Based on the position and free attitude angle, the parafoil system is simulated using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; 103: Obtained using the positioning system The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; 104: Perform deviation analysis based on the simulated motion trajectory and trajectory end position as well as the actual motion trajectory and trajectory end position to obtain a wind field estimation result; 105: According to the wind field estimation results, the three-stage homing method is used to correct the parafoil homing path in real time.

[0014] In one embodiment, for step 102, according to the flight position and attitude angle, the parafoil system is simulated using a six-degree-of-freedom dynamics model of the parafoil. The motion trajectory and the end position of the trajectory over time, including: The center of mass of the parafoil system is taken as the origin, the horizontal velocity direction of the parafoil is the positive direction of the x-axis, the vertical downward direction is the positive direction of the z-axis, and the y-axis direction is established according to the right-hand rule. In the body coordinate system, according to the position and free attitude angle, the parafoil system is simulated using the parafoil six-degree-of-freedom dynamics model. Movement trajectory in time and the end position of the trajectory .

[0015] In this embodiment, the derivation of the six-degree-of-freedom dynamic model of the parafoil system is based on the following assumptions: (1) Ignore the deviation between the center of mass and center of gravity of the parafoil system; (2) Ignore the rotation of the earth, that is, regard the ground coordinate system as an inertial system; (3) The parafoil system is a left-right symmetrical structure along the span direction.

[0016] Without considering the relative motion between the canopy and the load, the parafoil system is simplified to a single body model, assuming that the entire parafoil system is a rigid body, as shown in Figure 2. The parafoil system has six degrees of freedom, which are three translational degrees of freedom and three rotational degrees of freedom of the rigid body A.

[0017] Taking the target point on the ground as the origin, the due east direction is x Axis positive direction, due north direction is y Axis positive direction, vertically upward z The ground inertial coordinate system is established in the positive direction of the axis. Taking the center of mass of the parafoil system as the origin, the horizontal velocity direction of the parafoil is x Axis positive direction, vertically downward z Axis positive direction, y The axis direction is based on the right-hand rule to establish the body coordinate system.

[0018] Based on Newton's second law, the six-degree-of-freedom dynamic model of the parafoil system is derived as follows: Adding "~" to the letter representing the matrix represents an antisymmetric matrix, that is, cross-multiplication with the matrix on the right, such as Specifically expressed as formula (1), the matrix is formula (2), E is a unit matrix.

[0019] (1) (2) Assume the true mass of the parafoil system is , whose centroid is , the radius vector from the origin O of the ground inertial system to MC is , the corresponding radius vectors from point O to the roll center R and from point R to the pitch center P are and ; The velocity and angular velocity of point O are and ; The inertia tensor of the true mass of the parafoil system is , then the inertia tensor of the real mass relative to point O is As shown in formula (3), the inertia tensor of the additional mass relative to point O is As shown in formula (4): the true mass matrix of the parafoil system relative to point O As shown in formula (5), the additional mass matrix relative to point O is As shown in formula (6). (3) (4) (5) (6) in, Defined as: (7) In the formula , and represents the additional mass component of the parafoil.

[0020] Apply the momentum and angular momentum theorem to derive the intermediate terms, and let: (8) (9) (10) (11) In the formula, P and H denote momentum and angular momentum respectively, and their subscripts r and a represent the true mass term and the additional mass term respectively. and represents the momentum and angular momentum of the true mass relative to the coordinate origin O, and represents the momentum and angular momentum of the additional mass relative to the coordinate origin O. Assume that the subscripts of the aerodynamic and gravity terms of the force and moment are aero and ex , then the six-degree-of-freedom dynamic model of the parafoil system is: (11) In the formula, and are the aerodynamic force and aerodynamic torque, , is the gravity and gravitational torque, and , , , They represent the intermediate terms of force and torque in the derivation process of equations (8), (9), (10), and (11) respectively.

[0021] According to the initial state value of the parafoil system at the beginning of the homing, by numerically integrating equation (11) from the current moment to the next moment, the spatial position information and flight speed information of the parafoil system at the next moment can be obtained. By repeating this step continuously, the state information of the parafoil system at any subsequent moment can be obtained.

[0022] In the next embodiment, for step 104, deviation analysis is performed based on the simulated motion trajectory and trajectory end position and the actual motion trajectory and trajectory end position to obtain a wind field estimation result, including: 401: Perform deviation analysis based on the simulated motion trajectory and trajectory end position and the real motion trajectory and trajectory end position to obtain the position difference of the trajectory with and without the effect of the wind field; 402: Solve the wind field value based on the position difference.

[0023] In one embodiment, for step 104, if Figure 3 and 4 As shown, the direct flight trajectory NM Due to the wind field, it deviates from the arrival Point, turning segment trajectory PQ Due to the wind field, the final deviation from the arrival The trajectory before and after the wind field is divided into n segment, with each time period ∆ t i The sum of the distance difference between the two points on the flight trajectory is used to identify the wind field in this period. The sum of the position deviations of all corresponding points at each time on the two trajectories is calculated, and the predicted wind field is set as the independent variable. According to the minimum deviation principle, x Axis and y The wind speed value in the axial direction.

[0024] According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, deviation analysis is performed to obtain the position difference of the trajectory with and without the effect of wind field, including: According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, Simulation and real observation of the moment x The axis coordinates are and , y The axis coordinates are and ,but Time Track x Axis and y The axis coordinate deviation is:

[0025] set up n part Composed of The trajectory deviation during the period is:

[0026] In the formula, is the trajectory deviation.

[0027] In the next embodiment, for step 104, solving the wind field value according to the position difference includes: set up Wind field during the period , then use the least squares method to find Minimum wind field value:

[0028] In the formula is the trajectory deviation; is the identified wind field value.

[0029] In another embodiment, for step 105, the parafoil trajectory is connected in a certain geometric curve form during the homing process. In order to ensure that the parafoil can accurately reach the target point, the trajectory is planned into several segments, and control constraints are applied to each segment, so that the parafoil homing trajectory is designed to be segmented. The classic parafoil homing trajectory can be roughly divided into three segments, such as Figure 5 As shown, the parafoil system starts from point A, reaches point B after a period of gliding, and then performs a unilateral downward pull to make it turn at a constant yaw rate to reach point D, and finally reaches the target point G (O) through a bird landing. The whole process can be roughly regarded as three parts: straight flight, turning and bird landing.

[0030] According to the wind field estimation results, the three-stage homing method is used to correct the parafoil homing path in real time, including: According to the wind field estimation results, the wind field speed is projected into the ground inertial coordinate system with the target point as the origin. According to the geometric relationship of the trajectory, the analytical solution of the three homing trajectories is solved to obtain the accurate values ​​in the x, y and z directions. , considering the effect of wind field, we get formula (15): (15) In the formula, R is the turning radius; x A , y A and z A The starting point of the return A The coordinates of is the parafoil flight speed; is the component of the parafoil velocity in the z direction; is the initial yaw angle; is the landing yaw angle, which is determined by the wind field in the landing area; The time taken for the direct flight phase; The time taken for the turning phase; The time taken for the bird's landing stage; Assuming the yaw rate during the turning process is a constant value, the time consumed by the process is: (16) According to the consumption time , find the first flight time, that is, the time taken for the direct flight stage t LD for: (17) (18) in, The conditions for the parafoil system to reach the target point are: .

[0031] In the three-stage homing process, assuming that the parafoil starts homing and landing at an appropriate height, its basic trajectory is completed according to the process of straight flight-turn-drop. The specific steps are as follows: (1) Set a point in the flight trajectory A The trajectory planning starts from the initial point. It is considered that the wind field value at the initial point is the wind field of the entire subsequent homing process. The initial analytical solution of a homing trajectory starting from this point is solved according to formula (15).

[0032] (2) When the parafoil flies for one time step arrive After clicking, determine whether the preset landing height is met. If it is met, land and the return is completed; if not, proceed to the next step.

[0033] (3) Targeting Point wind field is identified and compared with AIf the difference between the two is within the acceptable range, If the difference exceeds the specified range, the current wind field is used as the new wind field data for trajectory replanning.

[0034] Repeat steps (2) and (3) until the parafoil lands.

[0035] This embodiment uses the measured wind field of a certain place to simulate and carry out step-length wind field identification for the parafoil precision airdrop system in the straight flight and turning states. The comparison between the identification results and the measured wind field is as follows: Figures 6 to 9 As shown in the figure, the two curves are very close, which shows the effectiveness of the patented method. x Axis and y The maximum error of the axial wind field identification is 0.15m / s, and the turning state of the parafoil system x The maximum error of the axis wind field identification is 0.52m / s, and the parafoil system is in a turning state. y The maximum error of wind field identification in the axial direction is 0.54m / s. This shows that this method is not only suitable for wind field identification in relatively stable flight conditions such as straight parafoil, but also for surrounding identification in non-steady-state conditions such as rapid turns, and can provide more accurate wind field information for the parafoil homing control system.

[0036] By using the real-time correction method for the parafoil homing path provided by the present invention, the homing result is as follows: Fig.10 As shown in the figure, it can be seen that the wind field identification and homing method proposed in this patent can enable the parafoil system to land accurately at the target point, and can be further applied to the existing precision airdrop system.

[0037] The present invention also provides a parafoil homing path real-time correction system, comprising: The information acquisition module is used to obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; the positioning system is used to obtain The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; The simulation module is used to simulate the parafoil system in the state of the parafoil according to the position and the free attitude angle using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; The wind field estimation module is used to perform deviation analysis based on the simulated motion trajectory and trajectory end position and the real motion trajectory and trajectory end position to obtain the wind field estimation result; The path correction module is used to correct the parafoil homing path in real time using the three-segment homing method according to the wind field estimation result.

[0038] The present invention also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method for real-time correction of the homing path of a parafoil when executing the computer program. The computer device may be a server. The computer device includes a processor, a memory, a network interface and a database connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store sample data. The network interface of the computer device is used to communicate with an external terminal via a network connection.

[0039] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the above-mentioned method for real-time correction of the homing path of a parafoil are implemented.

[0040] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0041] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0042] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A real-time correction method for a parafoil homing path, characterized in that: The following steps are involved: Obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; According to the position and free attitude angle, the parafoil system is simulated by using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; Using the positioning system to obtain The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, deviation analysis is performed to obtain the wind field estimation result; According to the wind field estimation result, the parafoil homing path is corrected in real time using the three-segment homing method.

2. The real-time correction method for the parafoil homing path according to claim 1, characterized in that: According to the position and free attitude angle, the parafoil system is simulated by using the parafoil six-degree-of-freedom dynamics model. The motion trajectory and the end position of the trajectory over time, including: Take the center of mass of the parafoil system as the origin, the horizontal velocity direction of the parafoil as the positive direction of the x-axis, the vertical downward direction as the positive direction of the z-axis, and the y-axis direction as the right-hand rule to establish the body coordinate system; In the body coordinate system, according to the position and free attitude angle, the parafoil system is simulated by using the parafoil six-degree-of-freedom dynamics model. Movement trajectory in time and the end position of the trajectory .

3. The real-time correction method for the parafoil homing path according to claim 1, characterized in that: According to the simulated motion trajectory and trajectory end position as well as the actual motion trajectory and trajectory end position, deviation analysis is performed to obtain the wind field estimation results, including: According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, deviation analysis is performed to obtain the position difference of the trajectory with and without the effect of wind field; The wind field value is solved according to the position difference.

4. The real-time correction method for the parafoil homing path according to claim 3, characterized in that: According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, deviation analysis is performed to obtain the position difference of the trajectory with and without the effect of wind field, including: According to the simulated motion trajectory and trajectory end position as well as the real motion trajectory and trajectory end position, Simulation and real observation of the moment x The axis coordinates are and , y The axis coordinates are and ,but Time Track x Axis and y The axis coordinate deviation is: set up n part Composition The trajectory deviation during the period is: In the formula, is the trajectory deviation.

5. The real-time correction method for the parafoil homing path according to claim 3, characterized in that: According to the position difference, the wind field value is solved, including: set up Wind field during the period , then use the least squares method to find Minimum wind field value: In the formula, is the trajectory deviation; is the wind field value.

6. The real-time correction method for the parafoil homing path according to claim 1, characterized in that: According to the wind field estimation result, the parafoil homing path is corrected in real time using the three-stage homing method, including: According to the wind field estimation results, the wind field velocity is projected into the ground inertial coordinate system with the target point as the origin. According to the geometric relationship of the trajectory, the analytical solution of the three homing trajectories is solved to obtain the accurate values ​​in the x, y and z directions. Considering the effect of the wind field, we get: In the formula, R is the turning radius; x A , y A and z A The starting point of the return A The coordinates of is the parafoil flight speed; is the component of the parafoil velocity in the z direction; is the initial yaw angle; is the landing yaw angle, which is determined by the wind field in the landing area; The time taken for the direct flight phase; The time taken for the turning phase; The time taken for the bird's landing stage; Assuming the yaw rate during the turning process is a constant value, the time consumed by the process is: According to the consumption time , find the first flight time, that is, the time taken for the direct flight stage t LD for: in, The conditions for the parafoil system to reach the target point are: .

7. A real-time correction system for a parafoil homing path, characterized in that: include: An information acquisition module is used to obtain the position and free attitude angle of the parafoil system in the geodetic inertial coordinate system with the target point on the ground as the origin; Using the positioning system to obtain The motion trajectory and trajectory end position of the parafoil system in the real wind environment within time; The simulation module is used to simulate the parafoil system in the state of the parafoil according to the position and the free attitude angle using the parafoil six-degree-of-freedom dynamics model. The trajectory of motion over time and the position of the end of the trajectory; The wind field estimation module is used to perform deviation analysis based on the simulated motion trajectory and trajectory end position and the real motion trajectory and trajectory end position to obtain the wind field estimation result; The path correction module is used to correct the parafoil homing path in real time using the three-segment homing method according to the wind field estimation result.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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