A piecewise energy management variable-curvature reference trajectory sliding mode control method

Abstract

The application discloses a segmented energy management variable-curvature reference trajectory sliding mode control method and belongs to the technical field of aircraft guidance control. Firstly, the constraints in the flight process of the aircraft are defined, including the continuous imaging oblique angle constraint, the force-thermal process constraint and the terminal constraint, and the virtual guide points in each stage are determined. Secondly, the reference circular trajectory parameters and the residual flight time of the aircraft flying to the virtual guide point are calculated according to the virtual guide point position in each stage. Finally, the maneuver load command and the angle of attack deflection angle are calculated according to the above variables. The application adopts the segmented energy management variable-curvature circular trajectory guidance, changes the circular curvature radius on line, saves energy at a long distance and quickly approaches the target area, considers the oblique angle and the hit constraint at a short distance, realizes the smooth and constrained lateral curve flight trajectory, provides long-time high-resolution SAR observation conditions for situation construction, and effectively solves the aircraft guidance control problem under the continuous imaging oblique angle constraint.

Description

Technical Field

[0001] This invention relates to the field of aircraft guidance and control technology, and in particular to a segmented energy management variable curvature reference trajectory sliding mode control method. Background Technology

[0002] Currently, aircraft guidance missions are increasingly trending towards higher precision, stronger constraints, and multi-condition operation. Terminal accuracy, attitude constraints, energy controllability, and trajectory adaptability have become the core constraints in guidance system design. As mission scenarios become more complex, aircraft often need to meet strict maneuver load constraints and angle constraints throughout the entire flight, while simultaneously achieving precise control of flight energy. Traditional guidance methods, such as proportional guidance, are gradually becoming inadequate for the multi-constraint control requirements of complex missions.

[0003] Traditional guidance strategies suffer from insufficient flexibility due to their single-curvature flight trajectory. They cannot dynamically adjust the trajectory shape according to the flight phase, making them prone to problems such as energy excess or deficiency, and the oblique angle not meeting detection requirements. Furthermore, the lack of segmented and refined management of flight energy results in poor guidance robustness when facing uncertainties such as initial state deviations, aerodynamic disturbances, and changes in mission parameters. This makes it difficult to simultaneously achieve the dual objectives of energy balance and angle constraints, directly limiting the spacecraft's mission execution capabilities in complex mission environments.

[0004] Among numerous constraints, the accurate construction of the oblique angle is a key prerequisite for the effective detection of the probe. The reliable construction of the oblique angle requires a smooth, controllable, and dynamically adjustable flight trajectory. At the same time, it requires the spacecraft's energy to be reasonably distributed in different guidance phases to avoid drastic fluctuations in trajectory and loss of angle control due to sudden energy changes, which would prevent the oblique angle required by the mission from being met. Summary of the Invention

[0005] The purpose of this invention is to provide a segmented energy management variable curvature reference trajectory sliding mode control method. Under the constraints of complex environments such as large maneuvers, high-speed dives, and terminal velocity angles of aircraft, a segmented energy management variable curvature circular trajectory guidance method is adopted. This method saves energy and allows for rapid approach to the target area at long distances, while at close distances, it balances constraints such as oblique angle and hit rate to design a small circular trajectory. By changing the radius of curvature online, a smooth and constrained lateral curve flight trajectory is achieved, providing long-term high-resolution SAR observation conditions for situation building, thereby solving the problem of continuous imaging oblique angle requirements.

[0006] To achieve the above objectives, the present invention provides a segmented energy management variable curvature reference trajectory sliding mode control method, comprising the following steps: S1. Construct a segmented energy management variable curvature circular guidance system; S2. Determine various constraints during the flight process of the aircraft through the continuous imaging constraint module; S3. Determine the number of virtual guidance points through the virtual guidance point calculation module; S4. Calculate the virtual guidance points for each stage using the virtual guidance point calculation module; S5. Determine the reference trajectory based on energy management through the control command generation module; S6. Determine the error between the aircraft position and the virtual reference circular trajectory through the control command generation module; S7. Determine the sliding mode control framework through the control command generation module; S8. Determine the sliding surface control formula through the control command generation module; S9. Determine the sliding mode controller through the control command generation module; S10. Determine the compliance status of each indicator through the performance indicator evaluation module.

[0007] Preferably, in step S1, the segmented energy management variable curvature circle guidance system includes: a continuous imaging constraint module, a virtual guidance point calculation module, a control command generation module, and a performance index evaluation module; The continuous imaging constraint module is used to define the terminal constraints of high-resolution imaging, mechanical and thermal process constraints, fall velocity, tilt angle, and accuracy during the flight of the aircraft. The virtual guidance point calculation module is used to calculate the virtual guidance points at each stage of the aircraft's flight. The control command generation module is used to generate guidance commands to control the flight of the aircraft; The performance evaluation module is used to evaluate the rationality of the virtual aircraft's point selection and the satisfaction of process constraints and terminal constraints during flight.

[0008] Preferably, in step S2, the constraints include continuous imaging oblique angle constraint, heat flow constraint, dynamic pressure constraint, mechanical load constraint, as well as drop speed constraint, tilt angle constraint, angle of attack constraint, and accuracy constraint.

[0009] Preferably, in step S3, the virtual guidance point calculation module determines the number of virtual guidance points to be 3 based on the actual flight process of the aircraft, and performs energy management based on the virtual guidance points at different stages.

[0010] Preferably, in step S4, the specific method for the virtual guidance point calculation module to calculate the virtual guidance points at each stage is as follows: For the In each stage, the ground distance of the virtual guidance point is The direction of entry is The virtual guide point position is shown in formula (1): ; In formula (1), For the first The location of the virtual guidance point in the stage. For the first The location of the virtual guidance point in the stage. For the first Ground distance of the virtual guide point in the stage For the first The direction of entry for the virtual guidance point in the stage; The virtual guidance point calculation module calculates the velocity of the aircraft reaching the virtual constraint point at each stage, as shown in formula (2): ; In formula (2), For the first The speed at which the stage vehicle reaches the virtual guidance point. The speed at which the spacecraft reaches the virtual guidance point in stage i-1. For the first Phase-specific vehicle acceleration, For the first Ground distance of the virtual guide point in the stage.

[0011] Preferably, in step S5, the control command generation module calculates the radius and trajectory of the reference circle trajectory based on the position vector and velocity vector of the virtual constraint point, and the position of the virtual reference circle trajectory is... The speed is .

[0012] Preferably, in step S6, the control command generation module determines the error between the aircraft position and the virtual reference circular trajectory, including position tracking error and velocity tracking error, and the calculation method is shown in formula (3): ; In formula (3), The error between the aircraft's position and the virtual reference trajectory, This represents the actual trajectory position of the aircraft. For virtual reference trajectory location information, The error between the aircraft speed and the virtual reference speed, The actual speed of the aircraft. This is a virtual reference speed.

[0013] Preferably, in step S7, the control command generation module determines the sliding mode control framework and defines the form of the sliding surface as shown in formula (4): ; In formula (4), For sliding mode control surface, The error between the aircraft speed and the virtual reference speed, The error between the aircraft's position and the virtual reference position, is a coefficient.

[0014] Preferably, in step S8, the control command generation module determines the sliding surface control formula, as shown in formula (5): ; In formula (5), For the mass of the aircraft, The derivative of the sliding mode control surface, The derivative of the error between the aircraft velocity and the virtual reference velocity. This is the derivative of the error between the aircraft's position and the virtual reference position. The net force acting on the aircraft.

[0015] Preferably, in step S9, the control command generation module determines the control formula of the sliding mode controller, as shown in formula (6): ; In formula (6), For the controller output based on the virtual reference trajectory, For control coefficients, It is a saturation function.

[0016] Therefore, the segmented energy management variable curvature reference trajectory sliding mode control method of the present invention, which adopts the above structure, has the following beneficial effects: (1) This invention adopts a segmented energy management variable curvature circular trajectory guidance method under the constraints of complex environments such as large maneuvers, high-speed dives, and terminal velocity angles of aircraft. It saves energy and quickly approaches the target area at long distances, and designs a small circular trajectory that takes into account constraints such as oblique angle and hit at close distances. By changing the radius of curvature online, a smooth and constrained lateral curve flight trajectory is achieved, providing long-term high-resolution SAR observation conditions for situation building.

[0017] (2) The present invention adopts a segmented energy management strategy, sets virtual guidance points in different flight stages, realizes precise control of flight energy, avoids drastic trajectory fluctuations caused by sudden energy changes, and improves the robustness of the guidance system in complex mission environments.

[0018] (3) This invention solves the trajectory control problem under the constraint of continuous imaging oblique angle by combining the sliding mode control framework with virtual reference trajectory tracking, effectively taking into account both energy balance and angle constraint.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a structural block diagram of the segmented energy management variable curvature circular guidance system of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Example like Figure 1 As shown, this invention provides a segmented energy management variable curvature reference trajectory sliding mode control method, specifically including the following steps: S1. Construct a segmented energy management variable curvature circular guidance system: such as... Figure 2 As shown, the segmented energy management variable curvature circle guidance system includes: a continuous imaging constraint module, a virtual guidance point calculation module, a control command generation module, and a performance index evaluation module.

[0024] The function of the continuous imaging constraint module is to define the terminal constraints of high-resolution imaging, force, heat and other process constraints, landing speed, tilt angle and accuracy during the flight of the aircraft.

[0025] The function of the virtual guidance point calculation module is to calculate the virtual guidance points at each stage of the aircraft's flight.

[0026] The function of the control command generation module is to generate guidance commands to control the flight of the aircraft.

[0027] The function of the performance evaluation module is to evaluate the rationality of the virtual aircraft's point selection and the satisfaction of process constraints and terminal constraints during flight.

[0028] S2. The continuous imaging constraint module determines various constraints during the flight of the aircraft. These constraints mainly include process constraints such as continuous imaging oblique angle constraints, heat flux, dynamic pressure, and maneuvering loads, as well as terminal constraints such as landing speed, tilt angle, angle of attack, and accuracy.

[0029] S3. The virtual guidance point calculation module determines the number of virtual guidance points: The virtual guidance point calculation module determines the number of virtual guidance points based on the actual flight process of the aircraft. In this embodiment, the number of virtual guidance points is 3. Energy management is performed based on the virtual guidance points at different stages. Specifically, a larger radius of curvature is set in the long-range stage to save energy and quickly approach the target area, while a smaller radius of curvature is set in the short-range stage to balance constraints such as oblique angle and hit rate.

[0030] S4. The virtual guidance point calculation module calculates the virtual guidance points for each stage: The virtual guidance point calculation module calculates the virtual guidance points for each stage, for the first stage... In each stage, the ground distance of the virtual guidance point is The direction of entry is The virtual guide point position is shown in formula (1): ; In formula (1), For the first The location of the virtual guidance point in the stage. For the first The location of the virtual guidance point in the stage. For the first Ground distance of the virtual guide point in the stage For the first The direction of entry for the virtual guidance point in the stage.

[0031] The virtual guidance point calculation module calculates the velocity of the aircraft reaching the virtual constraint point at each stage, as shown in formula (2): ; In formula (2), For the first The speed at which the stage vehicle reaches the virtual guidance point. The speed at which the spacecraft reaches the virtual guidance point in stage i-1. For the first Phase-specific vehicle acceleration, For the first Ground distance of the virtual guide point in the stage.

[0032] S5. The control command generation module determines the energy management-based reference trajectory: Based on the position and velocity vectors of the virtual constraint points, the control command generation module calculates the radius and trajectory of the reference circular trajectory. The position of the virtual reference circular trajectory is... The speed is By selecting different radii of curvature for the circular trajectory at different stages, coordinated optimization of energy management and oblique angle constraints can be achieved.

[0033] S6. The control command generation module determines the error between the aircraft position and the virtual reference circular trajectory: The control command generation module determines the error between the aircraft position and the virtual reference circular trajectory, including position tracking error and velocity tracking error. The calculation method is shown in formula (3): ; In formula (3), The error between the aircraft's position and the virtual reference trajectory, This represents the actual trajectory position of the aircraft. For virtual reference trajectory location information, The error between the aircraft speed and the virtual reference speed, The actual speed of the aircraft. This is a virtual reference speed.

[0034] S7. The control command generation module determines the sliding mode control framework: The control command generation module determines the sliding mode control framework and defines the form of the sliding surface as shown in formula (4): ; In formula (4), For sliding mode control surface, The error between the aircraft speed and the virtual reference speed, The error between the aircraft's position and the virtual reference position, This is a coefficient, which is selected based on the requirements of the system's convergence speed and steady-state accuracy.

[0035] S8. The control command generation module determines the sliding surface control formula: The control command generation module determines the sliding surface control formula, as shown in formula (5): ; In formula (5), For the mass of the aircraft, The derivative of the sliding mode control surface, The derivative of the error between the aircraft velocity and the virtual reference velocity. This is the derivative of the error between the aircraft's position and the virtual reference position. The net force acting on the aircraft.

[0036] S9. The control command generation module determines the sliding mode controller: The control command generation module determines the control formula of the sliding mode controller, as shown in formula (6): ; In formula (6), For the controller output based on the virtual reference trajectory, For control coefficients, The saturation function is used to effectively suppress chattering in sliding mode control and improve the engineering practicality of the control system.

[0037] S10. The performance evaluation module determines whether various indicators are met: This module determines whether process constraints such as continuous imaging oblique angle constraints, heat flux, dynamic pressure, and maneuvering loads, as well as terminal constraints such as landing speed, tilt angle, angle of attack, and accuracy, are met during the flight. It evaluates the degree of compliance of each indicator in real time during flight. When an indicator is found to be unmet, it performs online correction by adjusting the position of the virtual guide point or the parameters of the sliding mode controller to ensure that the aircraft meets all constraints throughout the entire flight.

[0038] Working Principle: This invention employs a segmented energy management variable curvature circular trajectory guidance method under various complex environmental constraints. First, the position and velocity of the virtual seeker point are determined. Then, a virtual reference circular trajectory is calculated. Next, a sliding mode control frame tracks the virtual reference trajectory. Finally, the satisfaction of various constraints is evaluated. By changing the circular curvature online, a smooth and constrained lateral curve flight trajectory is achieved, providing long-term high-resolution SAR observation conditions for situation building.

[0039] Therefore, the present invention adopts a segmented energy management variable curvature reference trajectory sliding mode control method with the above-mentioned structure. By combining the segmented energy management strategy and variable curvature reference trajectory design with the strong robustness of sliding mode control, the guidance and control problem of aircraft under continuous imaging oblique angle constraint is effectively solved.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A segmented energy management variable curvature reference trajectory sliding mode control method, characterized in that, Includes the following steps: S1. Construct a segmented energy management variable curvature circular guidance system; S2. Determine various constraints during the flight process of the aircraft through the continuous imaging constraint module; S3. Determine the number of virtual guidance points through the virtual guidance point calculation module; S4. Calculate the virtual guidance points for each stage using the virtual guidance point calculation module; S5. Determine the reference trajectory based on energy management through the control command generation module; S6. Determine the error between the aircraft position and the virtual reference circular trajectory through the control command generation module; S7. Determine the sliding mode control framework through the control command generation module; S8. Determine the sliding surface control formula through the control command generation module; S9. Determine the sliding mode controller through the control command generation module; S10. The performance evaluation module determines whether each indicator meets the requirements. When an indicator is found to be unsatisfactory, it is corrected online by adjusting the position of the virtual guidance point or the parameters of the sliding mode controller to ensure that the aircraft meets all constraints throughout the flight. In step S2, the constraints include continuous imaging oblique angle constraint, heat flow constraint, dynamic pressure constraint, maneuver load constraint, as well as fall speed constraint, tilt angle constraint, combined angle of attack constraint, and accuracy constraint. In step S3, the virtual guidance point calculation module determines the number of virtual guidance points to be 3 based on the actual flight process of the aircraft. Energy management is performed according to the virtual guidance points at different stages. A larger radius of curvature is set in the long-distance stage to save energy and quickly approach the target area, while a smaller radius of curvature is set in the close-distance stage to take into account both the oblique angle and the hit constraint. In step S4, the specific method for the virtual guidance point calculation module to calculate the virtual guidance points at each stage is as follows: For the In each stage, the distance between the virtual guidance points and the ground is... The direction of entry is The virtual guide point position is shown in formula (1): ； In formula (1), For the first The location of the virtual guidance point in the stage. For the first The location of the virtual guidance point in the stage. For the first Ground distance of the virtual guide point in the stage For the first The direction of entry for the virtual guidance point in the stage; The virtual guidance point calculation module calculates the velocity of the aircraft reaching the virtual constraint point at each stage, as shown in formula (2): ； In formula (2), For the first The speed at which the stage vehicle reaches the virtual guidance point. The speed at which the spacecraft reaches the virtual guidance point in stage i-1. For the first Phase-specific aircraft acceleration, For the first Ground distance of the virtual guidance point in the stage; In step S5, the control command generation module calculates the radius and trajectory of the reference circle trajectory based on the position and velocity vectors of the virtual constraint points. The position of the virtual reference circle trajectory is... The speed is By selecting different radii of curvature for circular trajectories at different stages, coordinated optimization of energy management and oblique angle constraints can be achieved.

2. The segmented energy management variable curvature reference trajectory sliding mode control method according to claim 1, characterized in that, In step S1, the segmented energy management variable curvature circle guidance system includes: a continuous imaging constraint module, a virtual guidance point calculation module, a control command generation module, and a performance index evaluation module; The continuous imaging constraint module is used to define the terminal constraints of high-resolution imaging, mechanical and thermal process constraints, fall velocity, tilt angle, and accuracy during the flight of the aircraft. The virtual guidance point calculation module is used to calculate the virtual guidance points at each stage of the aircraft's flight. The control command generation module is used to generate guidance commands to control the flight of the aircraft; The performance evaluation module is used to evaluate the rationality of the virtual aircraft's point selection and the satisfaction of process constraints and terminal constraints during flight.

3. The segmented energy management variable curvature reference trajectory sliding mode control method according to claim 1, characterized in that, In step S6, the control command generation module determines the error between the aircraft position and the virtual reference circular trajectory, including position tracking error and velocity tracking error, and the calculation method is shown in formula (3): ； In formula (3), The error between the aircraft's position and the virtual reference trajectory, This represents the actual trajectory position of the aircraft. For virtual reference trajectory location information, The error between the aircraft speed and the virtual reference speed, The actual speed of the aircraft. This is a virtual reference speed.

4. The segmented energy management variable curvature reference trajectory sliding mode control method according to claim 1, characterized in that, In step S7, the control command generation module determines the sliding mode control framework and defines the form of the sliding surface as shown in formula (4): ； In formula (4), For sliding mode control surface, The error between the aircraft speed and the virtual reference speed, The error between the aircraft's position and the virtual reference position, is a coefficient.

5. The segmented energy management variable curvature reference trajectory sliding mode control method according to claim 1, characterized in that, In step S8, the control command generation module determines the sliding surface control formula, as shown in formula (5): ； In formula (5), For the mass of the aircraft, The derivative of the sliding mode control surface, The derivative of the error between the aircraft velocity and the virtual reference velocity. This is the derivative of the error between the aircraft's position and the virtual reference position. The net force acting on the aircraft.

6. The segmented energy management variable curvature reference trajectory sliding mode control method according to claim 1, characterized in that, In step S9, the control command generation module determines the control formula of the sliding mode controller, as shown in formula (6): ； In formula (6), For the controller output based on the virtual reference trajectory, For control coefficients, It is a saturation function.

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