Vector deflection angle-based vertical / short-distance take-off and landing aircraft transition process trajectory optimization method

Abstract

The invention provides a vertical / short-distance take-off and landing aircraft transition process trajectory optimization method based on a vector deflection angle, belongs to the technical field of aircraft guidance and control, and aims to break through a traditional time variable-based trajectory optimization technology and establish a hovering-to-cruising and cruising-to-hovering transition process trajectory optimization strategy based on a thrust vector deflection angle. Firstly, a linear piecewise node sequence of a vector deflection angle in the process and time corresponding to each node to be optimized are established, a thrust vector piecewise linear deflection strategy is obtained, on this basis, a piecewise representation dynamical model with the vector deflection angle as an independent variable and a transition process to-be-optimized objective function of the piecewise representation dynamical model are constructed, and control constraints and performance constraints are combined, so that the thrust vector piecewise linear deflection strategy is obtained. And forming a transition process trajectory optimization model based on a vector deflection angle, and solving to obtain a system state, a control quantity sequence and a segmented deflection rule. Compared with a traditional trajectory optimization method based on time variables, the method has the advantages that the obtained mapping trajectory based on the vector deflection angle can directly reflect the evolution relation of each state variable, control input and the vector deflection angle in the transition process, and the method is more in line with the nature of system dynamics. Meanwhile, the thrust vector deflection strategy based on piecewise linear tilting is easy to implement, the rule is clear, and the engineering practical value is higher.

Description

Technical Field

[0001] This invention belongs to the field of aircraft guidance and control technology, and relates to a method for optimizing the trajectory of vertical / short takeoff and landing aircraft during the transition process based on vector deflection angle. Background Technology

[0002] Vertical / short takeoff and landing (V / STOL) aircraft combine the vertical takeoff and landing capabilities of traditional helicopters with the high-speed cruise performance of fixed-wing aircraft, thus demonstrating broad application prospects in low-altitude economic and emergency rescue missions. However, these aircraft face complex aerodynamic nonlinearities and flight-thrust coupling effects during the transition from vertical flight to horizontal cruise (or vice versa). Slight mishaps can lead to attitude instability or even loss of control, affecting flight safety. To ensure safety and stability throughout the flight, the trajectory of the transition process must be finely optimized to enable the aircraft to complete the transition in a controllable and smooth manner.

[0003] Existing transient trajectory optimization models, based on time variable definitions, can obtain temporal representations of system states and control variables. However, the optimization results of these temporal representations are difficult to reflect the correlation between state variables and thrust vector deflection angle during the transient process, making them challenging to apply in further analysis and control. In fact, during the transient process of vertical / short takeoff and landing (VTOL) aircraft, the main change in flight state is caused by the change in thrust vector deflection angle. Using the thrust vector deflection angle as the independent variable to describe the system evolution process can directly capture the causal relationship between attitude, aerodynamics, and thrust, making subsequent controller design easier. Summary of the Invention

[0004] The traditional time-evolution-based trajectory optimization problem for the transition process of vertical / short takeoff and landing (VTOL) aircraft is defined as follows: (1) Solving the trajectory optimization problem (1) yields the time-series representations of the system states and control variables. and However, the optimization results of the time series representation are difficult to reflect the correlation between the state variables and the thrust vector deflection angle during the transition process, making it difficult to apply in further analysis and control.

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for optimizing the transition trajectory of vertical / short takeoff and landing (VTOL) aircraft based on vector deflection angle. By transforming the traditional time-evolution-based trajectory problem into a configuration-evolution-based trajectory optimization problem, a transition trajectory that better conforms to the dynamics of VTOL aircraft is obtained.

[0006] A first aspect of the present invention provides a method for optimizing the transition trajectory of a vertical / short takeoff and landing (VTOL) aircraft based on vector deflection angle, comprising the following steps: S1: Establish the thrust vector deflection angle during the transition process of vertical / short takeoff and landing aircraft. linear segmented node sequence (2) and the time series corresponding to each node (3) The thrust vector deflection angle In horizontal Vertical Changes between; S2: Based on the thrust vector deflection angle node sequence, establish its piecewise linear tilting strategy: (4) Based on the piecewise linear tilt strategy, the traditional time variable is obtained. and thrust vector deflection angle variable The segmented mapping relationship between them: (5) in Thrust vector deflection angle increment Time increment ; S3: Based on the mapping relationship (5), the conventional dynamic differential equation with time as the independent variable is rewritten to form a piecewise dynamic model with the thrust vector deflection angle as the independent variable, as shown in equation (6): (6) in , For aircraft system status, This is the derivative of the system state with respect to time. S4: Based on the mapping relationship (5), the conventional integral performance index with time as the independent variable is rewritten, and the objective function for optimizing the transient process trajectory based on the thrust vector deflection angle is established, as shown in equation (7): (7) in and These are the final-state index function and the process index function, respectively, based on the time independent variable; while and The final-state index function and process index function are based on the thrust vector deflection angle. The weights of the final state index function, The weights are the process index functions.

[0007] S5: Combining the dynamic equations and the objective function, a transient trajectory optimization problem with the thrust vector deflection angle as the independent variable is established, as shown in equation (8): (8) in For the variable to be optimized, The objective function given by equation (7) is The dynamic equation after the transformation of equation (6) is: Represents the initial thrust vector deflection angle The initial state of the system , Represents the system control quantity The upper bound that should be satisfied and the lower realm constraint, This is the function for calculating system performance constraints. S6: Solve the optimization problem (8) to obtain the transient process system state sequence based on the thrust vector deflection angle. Control sequence Thrust vector deflection angle segmented node sequence and corresponding time node sequences Thus, the trajectory of the transition process can be obtained.

[0008] A second aspect of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for optimizing the transition trajectory of vertical / short takeoff and landing aircraft based on vector deflection angle as described in the above embodiments.

[0009] A third aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for optimizing the transition trajectory of a vertical / short takeoff and landing aircraft based on vector deflection angle.

[0010] A fourth aspect of the present invention provides a computer program product, including a computer program that, when executed, implements the above-described method for optimizing the transition trajectory of vertical / short takeoff and landing aircraft based on vector deflection angle.

[0011] This invention provides a novel trajectory optimization problem model for vertical / short takeoff and landing (V / STOL) aircraft by constructing a dynamic equation based on the thrust vector deflection angle and an objective function to be optimized. The model solves for the mapping relationship between the system states, actuators, and thrust vector deflection angle during the transition process, thus establishing a closed-loop trajectory. The algorithm is clearly defined, simple to implement, and has high engineering practical value, applicable to the design of hovering-to-cruise and cruise-to-hovering strategies for V / STOL aircraft. This overcomes the shortcomings of related technologies, such as the disconnect between the optimized system states and the thrust vector deflection angle, and the difficulty in controlling the thrust vector deflection pattern.

[0012] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0013] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A flowchart of a method for optimizing the transition trajectory of vertical / short takeoff and landing aircraft based on vector deflection angle, provided in an embodiment of the present invention; Figure 2 A schematic diagram of trajectory optimization results for the transition process of a vertical / short takeoff and landing aircraft based on vector deflection angle, according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present invention. Detailed Implementation

[0014] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0015] The following describes, with reference to the accompanying drawings, an embodiment of the present invention for trajectory optimization of the transition process of vertical / short takeoff and landing (VTOL) aircraft based on vector deflection angle. Addressing the problem mentioned in the background art that optimization results based on time-series representations are difficult to reflect the correlation between various state variables and the thrust vector deflection angle during the transition process, making further analysis and control difficult, the present invention provides a trajectory optimization method for the transition process of VTOL aircraft based on vector deflection angle. By transforming the traditional time-evolution-based trajectory problem into a configuration-evolution-based trajectory optimization problem, a transition process trajectory that better conforms to the dynamic essence of VTOL aircraft is obtained. This method can directly capture the causal relationship between "attitude-aerodynamics-thrust," facilitating subsequent controller design. It has advantages such as clear algorithm objectives, simple implementation, and high engineering practical value, and can be applied to the design of hover-to-cruise and cruise-to-hover strategies for VTOL aircraft. Thus, it solves the shortcomings of related technologies, such as the disconnect between the optimized system state and the thrust vector deflection angle, and the difficulty in controlling the thrust vector deflection law.

[0016] Specifically, Figure 1 The flowchart of the trajectory optimization method for the transition process of vertical / short takeoff and landing aircraft based on vector deflection angle provided by the present invention is shown.

[0017] Taking the hovering-to-cruise transition of a vertical / short takeoff and landing (V / STOL) aircraft as an example, the specific steps of the trajectory optimization method based on the thrust vector deflection angle are as follows: In step S101, the thrust vector deflection angle during the transition of a vertical / short takeoff and landing (VTOL) aircraft is established. linear segmented node sequence (1) The corresponding time series to be optimized for each node are as follows: (2) In step S102, based on the thrust vector deflection angle node sequence Establish its piecewise linear tilt strategy: (3) Based on the piecewise linear tilt strategy, the traditional time variable is obtained. and thrust vector deflection angle variable The segmented mapping relationship between them: (4) in Thrust vector deflection angle increment Time increment ; In step S103, based on the mapping relation (4), the conventional dynamic differential equation with time as the independent variable is rewritten to form a piecewise dynamic model with the thrust vector deflection angle as the independent variable, as shown in equation (5): (5) in , For aircraft system status, This is the derivative of the system state with respect to time. In step S104, based on the mapping relationship (4), the conventional integral performance index with time as the independent variable is rewritten, and the objective function for optimizing the transient process trajectory based on the thrust vector deflection angle is established, as shown in equation (6): (6) in The final state index function is designed here as follows: (7) in , , , , The body x Axis speed, body z Axis speed, pitch angle, pitch rate, flight altitude; , , , , To optimize the obtained system states at the thrust vector deflection angle of the above-mentioned parameters... The actual value at time, , , , , For the above system states, the thrust vector deflection angle is... The expected value at time , , , , The weights corresponding to the above system states are taken; in this embodiment, the weights are taken as follows: , , , , , , , , , .

[0018] For process index functions, this is designed as follows: (8) in This represents the height value at each thrust vector deflection angle. Let be the initial value of the height. In equation (6), the weight parameters for the final state index and the process index are taken as . , .

[0019] In step S105, by combining the dynamic equations and the objective function, a transient trajectory optimization problem with the thrust vector deflection angle as the independent variable is established, as shown in equation (9): (9) in For the variable to be optimized, The objective function given by equation (6) is The dynamic equation after the transformation of equation (5) is: Represents the initial thrust vector deflection angle The initial state of the system , Represents the system control quantity The upper bound that should be satisfied and the lower realm constraint, This is the function for calculating system performance constraints. In step S106, the optimization problem (9) is solved to obtain the transient process system state sequence based on the thrust vector deflection angle. Control sequence Thrust vector deflection angle segmented node sequence and corresponding time node sequences Thus, the trajectory of the transition process is obtained, such as Figure 2 As shown, this illustrates the optimized changes in altitude, airspeed, pitch angle, and pitch rate of a vertical / short takeoff and landing (V / STOL) aircraft during the hover-to-cruise transition with respect to the thrust vector deflection angle, rather than changes with time. During the hover-to-cruise transition, the thrust vector deflection angle gradually decreases from 90 degrees to 0 degrees, while the aircraft maintains a relatively constant altitude. Airspeed gradually increases as the thrust vector deflection angle decreases. The optimization results are clear and easy to analyze.

[0020] Figure 3 This is a schematic diagram of an electronic device provided according to an embodiment of the present invention. The electronic device may include: The memory 301, the processor 302, and the computer program stored on the memory 301 and capable of running on the processor 302.

[0021] When processor 302 executes the program, it implements the trajectory optimization method for the transition process of vertical / short takeoff and landing aircraft based on thrust vector deflection angle provided in the above embodiments.

[0022] Furthermore, electronic devices also include: Communication interface 303 is used for communication between memory 301 and processor 302.

[0023] The memory 301 is used to store computer programs that can run on the processor 302.

[0024] The memory 301 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0025] If the memory 301, processor 302, and communication interface 303 are implemented independently, then the communication interface 303, memory 301, and processor 302 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 3 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0026] Optionally, in a specific implementation, if the memory 301, processor 302, and communication interface 303 are integrated on a single chip, then the memory 301, processor 302, and communication interface 303 can communicate with each other through an internal interface.

[0027] Processor 302 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0028] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for optimizing the transition trajectory of vertical / short takeoff and landing aircraft based on thrust vector deflection angle.

[0029] This invention also provides a computer program product, including a computer program that, when executed, implements the above-described method for optimizing the transition trajectory of vertical / short takeoff and landing aircraft based on thrust vector deflection angle.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0033] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0034] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or more of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0035] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0036] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0037] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for trajectory optimization of a vertical / short take-off and landing aircraft transition process based on vector deflection angle, characterized in that, The method comprises the following steps: S1: Establishing the deflection angle of thrust vector in the transition process of vertical / short take-off and landing aircraft linear segment node sequence and the time sequence corresponding to each node; The linear segmented node sequence is shown in the following formula: ，（1） The time sequence corresponding to each node is shown in the following formula: ，（2） wherein the thrust vector deflection angle in the horizontal vertical between; S2: Based on the thrust vector deflection angle node sequence, a segmented linear deflection strategy is established, and the segmented linear deflection strategy is shown in the following formula: ，（3） Based on the piecewise linear tilting strategy, the piecewise mapping relationship between the traditional time variable and the thrust vector deflection angle variable is obtained, which is shown as follows: ，（4） wherein , thrust vector deflection angle increment , time increment ; S3: Based on the mapping relationship formula, rewrite the conventional dynamics differential equation with time as the independent variable to form a segmented representation dynamics model with the thrust vector deflection angle as the independent variable, and the model is shown in the following formula: ，（5） wherein, , is the system state of the aircraft, is the derivative of the system state with respect to time; S4: Based on the mapping relationship formula, rewrite the conventional integral performance index with time as the independent variable to establish a transition process trajectory optimization objective function based on the thrust vector deflection angle, and the objective function is shown in the following formula: ，（6） wherein, is an end state index function, is a process index function, is a weight of the end state index function, is a weight of the process index function; S5: Comprehensive dynamics equation and objective function, establish a transition process trajectory optimization problem with the thrust vector deflection angle as the independent variable, and the optimization problem is shown in the following formula: ，（7） wherein, is the variable to be optimized, is the objective function, is the transformed kinetic equation, represents the initial thrust vector angle the initial state of the system , represents the system control variable upper bound and lower bound constraints, is the system performance constraint calculation function; S6: solving the optimization problem to obtain the transition process system state sequence based on the thrust vector deflection angle , the control quantity sequence , the thrust vector deflection angle segment node sequence and the corresponding time node sequence , so as to obtain the transition process trajectory.

2. The method of claim 1, wherein, The sequence of the thrust vector deflection angle and the sequence of time nodes in the S1 are monotonically changed, for the hover-to-cruise process ; and for the cruise-to-hover process .

Images