Rocket power deceleration section adaptive guidance method based on indirect method

Abstract

The invention discloses a rocket power deceleration section adaptive guidance method based on an indirect method, and belongs to the technical field of aircraft control. The method comprises the following steps that speed prediction starting duration and position prediction engine throttling amplitude are conducted according to the current return state of a rocket, and when the preset conditions are jointly met, power deceleration section guidance starting is triggered; based on a minimum value principle of an indirect method, in a thrust non-adjustable scene, deducing to obtain a constraint capability of an attitude angle instruction, and determining the attitude angle instruction; and the y-direction position in an unbiased state is guaranteed based on a startup prediction result, and the energy deviation after startup is eliminated through thrust adjustment, so that the accurate constraint of the y-direction position is realized. According to the method, the adaptive capacity of the starting time to deviation is improved, the dual targets of attitude control and tail end state accurate constraint are achieved in the small-amplitude adjustable thrust scene, meanwhile, the opening degree limiting requirement of an engine is met, and the stability and reliability of the recycling process of the reusable rocket are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a rocket power deceleration stage adaptive guidance method based on an indirect method, belonging to the technical field of aircraft control. BACKGROUND

[0002] Due to the large flight span of the rocket recovery process, there are various process constraints and deviations, and at the same time, it is disturbed by environmental factors such as wind interference, so that the reusable rocket must rely on a strong guidance method to correct the deviation during the recovery process.

[0003] Among them, the power deceleration stage is a key stage between the front and the back in the recovery process. On the one hand, this stage needs to correct the speed and position deviation generated in the previous active stage; on the other hand, it also needs to provide an unbiased initial state for the subsequent aerodynamic deceleration stage, so the guidance effect of the power deceleration stage directly determines the success or failure of the rocket recovery.

[0004] However, the traditional reusable rocket power deceleration stage guidance method has obvious defects: it cannot simultaneously meet the three key requirements of adaptive start-up time, accurate end speed and position constraints, and engine opening constraints, resulting in difficulty in stable implementation of safe recovery of reusable rockets in complex scenarios with initial deviations, environmental disturbances or process constraints. SUMMARY

[0005] In order to solve the problems in the background art, the present application provides a rocket power deceleration stage adaptive guidance method based on an indirect method.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a rocket power deceleration stage adaptive guidance method based on an indirect method, the method comprising the following steps:

[0007] S1: According to the current return state of the rocket, the speed prediction start-up time and the position prediction engine throttle amplitude are predicted respectively, and when the speed prediction start-up time and the position prediction engine throttle amplitude jointly satisfy the preset condition, the power deceleration stage guidance start-up is triggered;

[0008] S2: Based on the minimum value principle of the indirect method, in the scene where the thrust is not adjustable, the constraint ability of the attitude angle command is derived to determine the attitude angle command;

[0009] S3: Based on the start-up prediction result of S1, the y-direction position in the unbiased state is guaranteed, and the energy deviation after start-up is eliminated by using thrust adjustment to realize accurate constraint of the y-direction position.

[0010] Further, the formula of the speed prediction start-up time in S1 is as follows:

[0011] (1)

[0012] In formula (1):

[0013] is the current mass of the rocket;

[0014] is the current rate of propellant consumption of the rocket;

[0015] is the specific impulse of the engine;

[0016] is the change in velocity of the rocket, where: represents the change in velocity in the x direction; represents the change in velocity in the y direction; represents the change in velocity in the z direction.

[0017] Further, the formula for predicting the engine throttle amplitude at position S1 is as follows:

[0018] (2)

[0019] In formula (2):

[0020] is the required thrust, where: represents the required thrust in the x direction; represents the required thrust in the y direction; represents the required thrust in the z direction;

[0021] is the target position, where: represents the target position in the x direction; represents the target position in the y direction; represents the target position in the z direction;

[0022] is the current position of the rocket;

[0023] is the current velocity of the rocket;

[0024] is the average gravitational force, where: represents the average gravitational force in the x direction; represents the average gravitational force in the y direction; represents the average gravitational force in the z direction; represents the current position gravitational force; is the target position gravitational force.

[0025] Further, the start-up equation at S1 is as follows:

[0026] (3)

[0027] In formula (3) :

[0028] is the rated thrust.

[0029] Further, the S2 comprises the following steps:

[0030] S201: determine the attitude angle command in the form of a procedure angle similar to iterative guidance:

[0031] (4)

[0032] In formula (4) :

[0033] represents the pitch angle;

[0034] represents the yaw angle;

[0035] represents the pitch velocity correction command;

[0036] represents the yaw velocity correction command;

[0037] represents the pitch direction position correction term;

[0038] represents the yaw direction position correction term;

[0039] all represent coefficients;

[0040] represents a time variable;

[0041] S202: solve the attitude angle command by predicting the terminal velocity and target position:

[0042] (5)

[0043] In formula (5) :

[0044] is the terminal velocity;

[0045] is the current position;

[0046] , , , all are intermediate variables and have no physical meaning; represents the rocket propellant combustion time.

[0047] Further, the S3 comprises the following steps:

[0048] S301: According to the y-direction position accurate constraint requirement, the y-direction demand thrust is calculated:

[0049] (6)

[0050] In formula (6):

[0051] V represents the current speed;

[0052] S302: Two other direction demand thrusts are obtained through formula (5):

[0053] (7)

[0054] In formula (7):

[0055] V represents the normalized coefficient of the thrust demand.

[0056] Compared with the prior art, the beneficial effects of the present application are:

[0057] The present application adopts the adaptive prediction start-up technology to dynamically match the flight state and deviation, improve the adaptability of the start-up opportunity to the deviation, derives the attitude angle command based on the indirect method, realizes the dual goals of attitude control and end state accurate constraint in the small amplitude thrust adjustable scene, eliminates the energy deviation through the thrust adjustment mechanism and guarantees the y-direction position without deviation transmission, and meets the engine opening limit requirement at the same time. The overall scheme has strong robustness to engineering errors such as aerodynamic interference, thrust deviation and thrust adjustment delay, effectively reduces the subsequent aerodynamic deceleration segment guidance pressure, and improves the stability and reliability of the reusable rocket recovery process. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is a flowchart of the present application. DETAILED DESCRIPTION

[0059] The technical solutions in the present application will be described clearly and completely in the embodiments of the present application combined with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0060] A rocket power deceleration segment adaptive guidance method based on the indirect method, the method comprises the following steps:

[0061] S1: According to the current return state of the rocket, the speed prediction start-up time and the position prediction engine throttle amplitude are respectively carried out, and when the speed prediction start-up time and the position prediction engine throttle amplitude jointly satisfy the preset condition, the power deceleration section guidance start-up is triggered;

[0062] S2: Based on the minimum value principle of the indirect method, in the scene where the thrust is not adjustable, the constraint ability of the attitude angle instruction is derived, and the attitude angle instruction is determined;

[0063] S3: Based on the start-up prediction result of S1, the y-direction position in the unbiased state is guaranteed, the energy deviation after start-up is eliminated by using thrust adjustment, and the accurate constraint of the y-direction position is realized.

[0064] Further, the speed prediction start-up time of S1 is based on the Tsiolkovsky formula, and the specific formula is as follows:

[0065] (1)

[0066] In formula (1):

[0067] is the current mass of the rocket;

[0068] is the rocket propellant consumption per second;

[0069] is the specific impulse of the engine;

[0070] is the rocket speed change amount, wherein: represents the change amount of the speed in the x-direction; represents the change amount of the speed in the y-direction; represents the change amount of the speed in the z-direction.

[0071] Further, the formula of the position prediction engine throttle amplitude of S1 is as follows:

[0072] (2)

[0073] In formula (2):

[0074] is the required thrust, wherein: represents the x-direction required thrust; represents the y-direction required thrust; represents the z-direction required thrust;

[0075] is the target position, wherein: represents the x-direction target position; represents the y-direction target position; represents the target position in the z direction;

[0076] is the current position of the rocket;

[0077] is the current velocity of the rocket;

[0078] is the average gravitational force, wherein: represents the average gravitational force in the x direction; represents the average gravitational force in the y direction; represents the average gravitational force in the z direction; represents the current position gravitational force; is the target position gravitational force.

[0079] Further, the start-up equation of S1 is as follows:

[0080] (3)

[0081] In formula (3):

[0082] is the rated thrust.

[0083] Further, the S2 includes the following steps:

[0084] S201: Determine the attitude angle command in the form of a program angle similar to iterative guidance:

[0085] (4)

[0086] In formula (4):

[0087] represents the pitch angle;

[0088] represents the yaw angle;

[0089] represents the pitch velocity correction command;

[0090] represents the yaw velocity correction command;

[0091] represents the pitch direction position correction term;

[0092] represents the yaw direction position correction term;

[0093] all represent coefficients;

[0094] represents a time variable;

[0095] S202: Solve the attitude angle command by predicting the terminal velocity and target position:

[0096] (5)

[0097] In formula (5):

[0098] is the terminal velocity;

[0099] is the current position;

[0100] , , , are all intermediate variables without physical meaning; represents the rocket propellant combustion time.

[0101] Further, the S3 comprises the following steps:

[0102] S301: Calculate the y-direction demand thrust according to the y-direction position accurate constraint requirement:

[0103] (6)

[0104] In formula (6):

[0105] represents the current velocity;

[0106] S302: Obtain the demand thrust of the other two directions by formula (5):

[0107] (7)

[0108] In formula (7):

[0109] represents the normalized coefficient of the thrust demand.

[0110] It is obvious for those skilled in the art that the present application is not limited to the details of the above-mentioned exemplary embodiments, and can be implemented in other forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent conditions of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0111] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A method of adaptive guidance for a rocket powered de-orbiting stage based on an indirect method, characterized in that: The method comprises the following steps: S1: according to the current return state of the rocket, respectively, the speed prediction start-up time and the position prediction engine throttle amplitude are carried out, when the speed prediction start-up time and the position prediction engine throttle amplitude jointly satisfy the preset condition, the power deceleration section guidance start-up is triggered; S2: based on the minimum value principle of the indirect method, in the scene where the thrust is not adjustable, the constraint ability of the attitude angle instruction is derived, and the attitude angle instruction is determined; S3: based on the start-up prediction result of S1, the y-direction position in the unbiased state is ensured, the energy deviation after start-up is eliminated by using thrust adjustment, and the accurate constraint of the y-direction position is realized.

2. The adaptive guidance method for a powered rocket deceleration phase based on indirect method according to claim 1, characterized in that: The formula of the speed prediction start-up time in S1 is as follows: (1) In formula (1): M is the current mass of the rocket; For rocket propellant second consumption; Specific impulse for the engine; is a rocket velocity change amount, where: represents a change amount of the velocity in the x direction; represents a change amount of the velocity in the y direction; represents a change amount of the velocity in the z direction.

3. The indirect method based adaptive guidance method for a rocket powered de-orbiting stage according to claim 2, wherein: The formula of the position prediction engine throttle amplitude in S1 is as follows: (2) In formula (2): Fxdemanded = Fxdemanded + Fydemanded + Fzdemanded Fxdemanded represents the x-direction demanded force; Fydemanded represents the y-direction demanded force; Fzdemanded represents the z-direction demanded force; Target position, wherein: represents an x-direction target position; represents a y-direction target position; represents a z-direction target position; R is the current position of the rocket; Vr is the current velocity of the rocket; is the average attraction, where: represents the average attraction in the x direction; represents the average attraction in the y direction; represents the average attraction in the z direction; represents the current position attraction; is the target position attraction.

4. The indirect method based adaptive guidance method for a rocket powered de-orbiting stage according to claim 3, wherein: The start-up equation in S1 is as follows: (3) In formula (3): For rated thrust.

5. The rocket powered de-orbit stage adaptive guidance method based on indirect method according to claim 4, characterized in that: The S2 comprises the following steps: S201: the attitude angle instruction is determined in the form of a similar program angle as iterative guidance: (4) In formula (4): denotes the pitch angle; denotes the yaw angle; represents a pitch velocity correction command; represents a yaw velocity correction command; represents a pitch direction position correction term; represents a yaw direction position correction term; each represents a coefficient; denotes the time variable; S202: the attitude angle instruction is solved by predicting the terminal speed and the target position: (5) In formula (5): Vt is the terminal velocity; current position; , , , are intermediate variables and have no physical meaning; represents the rocket propellant combustion time.

6. The indirect method based adaptive guidance method for a rocket powered de-orbiting stage according to claim 5, wherein: The S3 comprises the following steps: S301: according to the y-direction position accurate constraint requirement, the y-direction required thrust is calculated: (6) In formula (6): represents the current speed; S302: the required thrust of the other two directions is obtained through formula (5): (7) In formula (7): a normalized coefficient representative of the thrust demand.

Images