A reusable rocket landing section start height prediction method, guidance system and processor

Abstract

The application provides a reusable rocket landing section starting height prediction method, a guidance system and a processor. By constructing a real-time online starting height prediction model based on the energy conservation principle, and combining multiple safety thresholds (including an allowable starting height upper limit and a backup starting height lower limit), the engine ignition timing is dynamically and accurately determined, ensuring safety and fuel optimization within the full flight envelope, thereby significantly improving the reliability, accuracy and economy of reusable rocket landing. The application solves the problems of insufficient prediction accuracy and robustness of the engine starting height, inability to adapt to complex flight environment uncertainty online, and insufficient safety margin consideration in the prior art, and completely eliminates potential safety risks.

Description

Technical Field

[0001] This invention relates to the field of aerospace launch vehicle technology, and in particular to a method for predicting the starting altitude of a reusable rocket landing phase, a guidance system, and a processor. Background Technology

[0002] Vertical landing of reusable rockets is a key technology for reducing space launch costs and achieving sustainable development of the space economy. Precise control of engine retro-propulsion ignition timing is crucial for ensuring a safe and successful landing mission and achieving optimal fuel utilization. During its return from high altitude to Earth, the rocket undergoes complex flight phases: from aerodynamic deceleration in the hypersonic, thin atmosphere (typically accompanied by high heat flux and blackout) to subsonic / transonic aerodynamic deceleration in the dense atmosphere, culminating in engine retro-propulsion braking for landing. The terminal states of the aerodynamic deceleration phase, such as flight speed, altitude, attitude, and trajectory inclination, have a decisive impact on the timing of subsequent engine retro-propulsion ignition.

[0003] Traditional methods for determining engine start-up altitude often have significant limitations, which can easily lead to compromises in the safety or economy of the landing process.

[0004] Traditional Method 1: Pre-set fixed altitude ignition. This is the simplest and most direct method, where the rocket ignites when it descends to a fixed altitude. However, this method lacks adaptability to the uncertainties of actual flight.

[0005] Traditional Method Two: Launch Prediction Based on Nominal Trajectory. This method pre-calculates an optimal or nominal landing trajectory and tracks it during flight. When the rocket reaches the preset ignition altitude on the trajectory, it commands the rocket to launch. This method considers rocket dynamics, but its ability to correct for actual deviations (such as real-time mass changes, aerodynamic uncertainties, and wind disturbances) online is limited.

[0006] Traditional Method 3: Simply relying on the speed-altitude relationship to determine the ignition timing. This method may be based on a preset speed-altitude curve to determine the ignition timing, which is difficult to optimize in real time and may lead to suboptimal fuel use.

[0007] These shortcomings of existing technologies collectively lead to the following problems: suboptimal fuel consumption, increased safety risks, poor adaptability to uncertainties, and insufficient consideration of safety margins.

[0008] Therefore, there is an urgent need to provide an altitude prediction method that can predict engine start-up altitude in real time and accurately, has strong robustness to cope with various uncertainties, and takes into account both fuel optimization and flight safety. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a reusable rocket landing phase start-up altitude prediction method, guidance system, and processor. This solves the problems of insufficient accuracy and robustness in engine start-up altitude prediction, inability to adapt to uncertainties in complex flight environments online, and insufficient consideration of safety margins in the prior art, thus completely eliminating potential safety risks.

[0010] This invention provides a method for predicting the starting altitude of a reusable rocket landing phase, comprising at least the following steps:

[0011] Step 1: Define the boot decision window ( ), and ( Set as a safety threshold. To allow a maximum boot height, To ensure the minimum startup height;

[0012] Step 2: Based on the principle of energy conservation, construct a system that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. ;

[0013] Step 3: At the end of the rocket's aerodynamic deceleration phase, the rocket enters the activation decision window. After that, the current trajectory inclination angle of the rocket is calculated online. And based on the rocket's current trajectory inclination obtained in real time. Calculate the theoretical startup height ;

[0014] Step 4: In the entire startup decision window ( Within the range, continuously monitor the rocket's current altitude. And the theoretical boot height calculated in real time And combined with preset security thresholds ( Make the power-on decision;

[0015] Step 5: During the power-on decision-making process, determine the rocket's current altitude. If the main control system meets the start-up conditions, the system will immediately instruct the engine to ignite and start up. If not, the start-up decision will continue.

[0016] Furthermore, the determination of the rocket's current altitude The method to determine if the main control system startup conditions are met is as follows: simultaneously check whether the rocket's current altitude has reached or fallen below the theoretical startup altitude, and whether the rocket's current altitude is within the installation threshold. To make a judgment; if the rocket's altitude during the descent and landing process... Reaching or falling below the theoretical power-on height calculated online ,and < ≤ If the ignition command is triggered, the guidance system will immediately send an ignition command to the rocket engine controller and record the moment of the ignition command as the actual start-up time; otherwise, it will continue to make the start-up decision.

[0017] Furthermore, the rocket enters the power-on decision window ( After that, the current trajectory inclination angle of the rocket is calculated online. The method is as follows: the guidance system obtains the rocket's real-time velocity vector in the landing coordinate system from the onboard navigation system at a high frequency. Through the formula: The current trajectory inclination of the rocket was calculated. ;in, Let X be the horizontal X-axis velocity component of the rocket in the landing frame. Let be the velocity component of the rocket along the vertical Y-axis in the landing frame. Let be the horizontal velocity component of the rocket along the Z-axis in the landing system.

[0018] Furthermore, based on the principle of energy conservation, a system is constructed that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. The method is as follows: based on the energy balance equation:

[0019] Real-time prediction of the optimal theoretical startup height ;in, Standard startup thrust; For thrust-induced aerodynamic disturbance force; To provide real-time mass estimation for the rocket; It is the acceleration due to gravity; This is the rocket's current trajectory inclination angle; For the real-time velocity of the rocket under landing system, i.e. ; The theoretical mass of the rocket at the nominal startup moment; The theoretical velocity of the rocket at the nominal startup moment corresponds to The speed at that time; This refers to the nominal startup height.

[0020] Furthermore, during the decision-making process for activating the rocket, the current altitude of the rocket is determined. Reaching or falling below the theoretical power-on height calculated online The method is as follows: using the formula: Make a judgment where 0.3m≤ ≤1m, used to handle calculation and measurement errors.

[0021] Furthermore, it simultaneously checks whether the rocket's current altitude has reached or fallen below the theoretical startup altitude, and whether the rocket's current altitude is within the installation threshold. During the judgment process, if the main control power-on condition is not triggered, once the rocket's current altitude... Down to The system will then forcefully instruct the engine to start.

[0022] Furthermore, the aforementioned The setting is at the highest point where the rocket can actually safely perform retro-rockets deceleration; It is set at the lowest point that allows the rocket to safely decelerate to zero within the remaining distance after ignition.

[0023] Furthermore, the thrust-induced aerodynamic disturbance force Based on the real-time velocity of the rocket under the aforementioned landing system Dynamic corrections are made, and the values ​​are obtained from wind tunnel test data, computational fluid dynamics simulations, or empirical models.

[0024] Another aspect of the present invention provides a guidance system, comprising at least: a preset module, a measurement module, a calculation module, a decision module, and a control module; the preset module is used to define the power-on decision window (…). ), and construct a system for calculating the theoretical boot height. The energy balance equation; the measurement module is used to monitor the rocket's current altitude. Thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbance force, etc.; the calculation module is used to calculate the rocket's current trajectory inclination angle in real time. And based on the rocket's current trajectory inclination obtained in real time. Theoretical calculation of thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbance force at startup height. The decision module is used to compare the rocket's current altitude. Compared with the theoretical start-up height And combined with preset security thresholds ( The control module makes the start-up decision; it receives the start-up command from the decision module and controls the engine to ignite and start.

[0025] The present invention also provides a processor for executing the steps in the reusable rocket landing phase start-up altitude prediction method in any of the above embodiments.

[0026] The present invention provides a reusable rocket landing phase start-up altitude prediction method, guidance system, and processor, which have at least one of the following beneficial effects:

[0027] I. This invention, based on the principle of energy conservation, calculates the trajectory inclination angle online in real time and accurately considers thrust-induced aerodynamic disturbances, constructing an energy balance equation that more closely reflects actual flight physics. This allows the predicted launch altitude to dynamically and accurately reflect the rocket's real-time state, avoiding prediction errors caused by model simplification or fixed parameters in traditional methods.

[0028] II. This invention introduces an upper limit to the allowable power-on height. and backup power-on height limit The dual safety mechanism ensures that the rocket can be started safely and in a timely manner under various uncertainties (such as changes in atmospheric environment, aerodynamic model errors, engine performance deviations, and sensor failures), effectively avoiding fuel waste caused by starting the rocket too early and the impact risk caused by starting it too late, thus significantly improving the reliability of the system.

[0029] Third, this invention differs from traditional methods that rely on preset trajectories or fixed thresholds. This invention can adapt in real-time to changes in the rocket's current velocity, mass, and trajectory inclination. Even when the actual flight trajectory deviates from the nominal value, it can dynamically adjust the startup strategy to ensure accurate landing. This invention integrates a precise compensation mechanism for real-time trajectory inclination and thrust-induced aerodynamic disturbances, making the energy model more consistent with actual physical conditions. This significantly improves the physical realism and accuracy of startup altitude prediction, especially crucial when the rocket is descending at a large inclination or at high speed.

[0030] Fourth, this invention innovatively constructs an energy balance equation encompassing the real-time kinetic energy, potential energy, engine thrust, gravitational work, and thrust-induced aerodynamic disturbance work of the rocket. By analytically solving for the theoretical optimal engine altitude in real time, it can dynamically adapt to changes in the actual flight state of the rocket (such as mass, velocity, and trajectory inclination), ensuring optimal prediction accuracy and fuel consumption, and overcoming the limitations of traditional fixed-point or preset trajectory methods.

[0031] Upon reading the detailed embodiments and examining the accompanying drawings, those skilled in the art will recognize additional features and advantages. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of the reusable rocket landing segment start-up altitude prediction method according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram illustrating the principle of the reusable rocket landing segment start-up altitude prediction method according to an embodiment of the present invention. Detailed Implementation

[0035] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and to exemplify the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the dimensions of some structural components or regions in the drawings may be enlarged for other structural components or regions to aid in the understanding of the embodiments of the present invention.

[0036] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise stated, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0037] Furthermore, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure or component that includes a list of elements includes not only those elements but also other structural elements that are not expressly listed or inherent to the structure or component. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the article or apparatus that includes the element.

[0038] Spatial relation terms such as "below," "under," "under," "low," "above," "on," and "high" are used for descriptive convenience to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device, in addition to those different from those shown in the figure. Furthermore, phrases such as "one element on / below another element" can indicate that two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first" and "second" are also used to describe individual elements, areas, parts, etc., and should not be considered limiting. Similar terms are used throughout the description to refer to similar elements.

[0039] It will be apparent to those skilled in the art that the present invention can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention.

[0040] To address the following problems existing in the prior art:

[0041] 1) Suboptimal fuel consumption: If the rocket is activated too early, it will perform retro-thrust at an unnecessary altitude, consuming a large amount of fuel that could have been avoided, thus reducing the core economic advantage of reusable rockets.

[0042] 2) Increased safety risks: If the launch is delayed, the rocket may not be able to reach the ground at a safe speed due to insufficient deceleration distance, resulting in an impact that seriously threatens mission safety and hundreds of millions of dollars in assets.

[0043] 3) Poor adaptability to uncertainty: The thrust adjustment range of liquid oxygen-methane rockets is typically limited (e.g., for nine engines, there may be a limitation between the minimum thrust of a single engine and the maximum thrust of three engines), making them particularly sensitive to the timing of engine activation. Existing technologies generally lack the ability to adapt online and in real time to factors such as changes in the atmospheric environment, uncertainties in aerodynamic characteristics, errors in rocket mass estimation, and deviations in engine performance.

[0044] 4) Insufficient consideration of safety margin: Existing technologies often do not adequately consider how to enhance the robustness of start-up decisions through explicit safety margins, making it difficult to achieve fuel optimization while ensuring safety.

[0045] To address the problems existing in the prior art, this invention provides a method for predicting the startup altitude of a reusable rocket landing phase. This method constructs a real-time online startup altitude prediction model based on the principle of energy conservation, and combines multiple safety thresholds (including the upper limit of the allowed startup altitude). and backup power-on height limit This allows for the dynamic and precise determination of engine ignition timing, ensuring safety and fuel optimization throughout the entire flight envelope, thereby significantly improving the reliability, accuracy, and economy of reusable rocket landing.

[0046] See Figure 1 The reusable rocket landing phase start-up altitude prediction method of this embodiment includes at least the following steps:

[0047] S10, Define the boot decision window ( ), and ( Set as a safety threshold. To allow a maximum boot height, To ensure the minimum startup height;

[0048] S20. Based on the principle of energy conservation, construct a system that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. ;

[0049] S30. At the end of the rocket's aerodynamic deceleration phase, the rocket enters the start-up decision window. After that, the current trajectory inclination angle of the rocket is calculated online. And based on the rocket's current trajectory inclination obtained in real time. Calculate the theoretical startup height ;

[0050] S40, in the entire boot decision window ( Within the range, continuously monitor the rocket's current altitude. And the theoretical boot height calculated in real time And combined with preset security thresholds ( Make the power-on decision;

[0051] S50, during the startup decision-making process, determines the rocket's current altitude. If the main control system meets the start-up conditions, the system will immediately instruct the engine to ignite and start up. If not, the start-up decision will continue.

[0052] The maximum allowable boot height in this embodiment As a safety threshold to prevent rockets from starting prematurely due to accidents or misjudgments, it is usually set at the highest point where the rocket can actually safely perform reverse thrust deceleration, avoiding ineffective reverse thrust when the energy state is poor or aerodynamic forces are still dominant, thereby preventing unnecessary excessive fuel consumption.

[0053] The lower limit of backup power-on height in this embodiment This serves as the minimum safety altitude to prevent a rocket from failing to start due to accidents or predicted failures. It is the minimum safe threshold at which the rocket must ignite. Below this altitude, it may not be able to safely decelerate to zero within the remaining distance. This ensures that even in extreme cases where the main control system fails to activate, the rocket can still be forced to ignite and decelerate, minimizing the risk of impact.

[0054] Furthermore, the security boundary of the boot decision window can no longer be a fixed value, but can be dynamically adjusted based on environmental parameters. ,and For example, adjustments can be made dynamically based on environmental and state parameters such as real-time atmospheric density, wind speed, wind direction, and rocket mass estimation errors. When wind speed is high or mass estimation uncertainty is high, the safety window can be appropriately expanded, or the lower limit can be adjusted to reserve more margin.

[0055] See Figure 2 , Figure 2 This is a schematic diagram used to visually illustrate the relationship between the core concepts and key parameters of the reusable rocket landing phase start-up altitude prediction method in this embodiment. Figure 2 The X and Y arrows in the diagram indicate the coordinate axes in the landing frame, with the Y direction representing the vertical (altitude) direction and the X direction representing the horizontal direction.

[0056] Figure 2 The curve in the image illustrates the rocket's descent trajectory during the reentry phase. The actual handover point is shown in the image. J This represents the actual point where the rocket transitions from the aerodynamic deceleration phase to the engine reaction-driven deceleration phase; the actual handover point. J This refers to the actual ignition point of the engine when the main control unit's start-up conditions are met. (Theoretical handover point) J 'Represents the expected engine thrust reverser ignition location on the mission design trajectory, which is usually an ideal point calculated based on nominal conditions.'

[0057] This indicates a standard or reference nominal startup height. This is a reference point preset during the design phase.

[0058] : Represents the rocket's trajectory inclination angle at the current moment, i.e., the rocket's velocity vector. The angle between the rocket and the horizontal plane. It reflects the degree of tilt during the rocket's descent and has a significant impact on the deceleration distance.

[0059] This invention provides a real-time online calculation of the predicted startup altitude based on energy. This is the output of the core algorithm of this invention, representing the actual altitude during the rocket's landing process. Reaching or falling below this predicted altitude The time is the basis for triggering the main controller's power-on conditions.

[0060] This represents the difference between actual energy and theoretical energy, and may reflect the energy loss or gain caused by various uncertainties during flight (such as atmospheric disturbances, mass estimation errors, engine performance deviations, etc.).

[0061] : indicates a displacement Internal average thrust The work done. The average thrust here. Engine thrust was taken into account and thrust-induced aerodynamic disturbance force The combined effect.

[0062] : Indicates a specific ballistic inclination angle Below, the standard start-up height is calculated using energy conservation. To the predicted startup height The required vertical distance. It indicates the distance that needs to be reversed in the vertical direction.

[0063] This invention is used for real-time calculation of energy start-up height. The core mathematical model is:

[0064] .

[0065] The reusable rocket landing phase startup altitude prediction method in this embodiment uses energy startup altitude... The formula's real-time calculations enable the rocket to reduce its speed to zero and land safely at the predicted altitude by consuming the most economical amount of fuel, through the combined effects of thrust, gravity, and aerodynamic forces.

[0066] Furthermore, when the rocket reaches altitude Enter the startup decision window ( When the power-on height prediction logic starts working, the power-on height prediction logic becomes active.

[0067] For example, the rocket enters the power-on decision window ( After that, the guidance system will obtain the rocket's real-time velocity vector in the landing coordinate system from the onboard navigation system (such as a combined navigation system, IMU / GPS fusion) at a high frequency (e.g., every 20ms). .in, Let X be the horizontal X-axis velocity component of the rocket in the landing frame. Let be the velocity component of the rocket along the vertical Y-axis in the landing frame. This represents the rocket's horizontal Z-axis velocity component under the landing system. Based on these real-time measurements, the rocket's current trajectory inclination angle is calculated accurately online. The trajectory inclination angle is defined as the angle between the rocket's velocity vector and the horizontal plane, and its calculation formula is: .in, It is a four-quadrant arctangent function, which can correctly handle the quadrants of angles. This indicates the magnitude of the rocket's horizontal speed.

[0068] The ballistic tilt angle in this embodiment The real-time and accurate acquisition of energy balance equations is crucial for establishing the equations, as it precisely reflects the tilt of the rocket's current flight trajectory, thus affecting the required deceleration distance and fuel consumption.

[0069] Furthermore, based on the principle of energy conservation, the S200 constructs a system that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. The method involves fully considering the changes in the rocket's kinetic and potential energy from the current state to the landing point (target velocity and target altitude are zero), as well as the effects of engine thrust, gravity components, and aerodynamic work. The basic physical idea is that after ignition at the predicted start-up altitude, the work done by the engine retro-thrust minus the work done by gravity, and then minus the work done by the thrust-induced aerodynamic interference force, should precisely offset the changes in the rocket's kinetic and potential energy from the start-up point to the ground.

[0070] After derivation, the real-time energy start-up height was obtained. The calculation formula is as follows:

[0071] Based on the energy balance equation, the optimal theoretical start-up height is predicted in real time. .

[0072] in, Standard start-up thrust refers to the rated thrust generated after the engine is ignited. It is the engine working thrust value preset for a safe landing mission (for example, it may be 100% thrust of three engines).

[0073] Thrust-induced aerodynamic interference force. This refers to the additional aerodynamic force generated by the interaction between the retro-thrust plume and the external airflow of the rocket after the engine is started. It is a component of the rocket's real-time velocity. The function of this term compensates for the shortcomings of traditional aerodynamic models that only consider incoming flow drag, making the predicted start-up altitude more consistent with actual physical conditions. Its value can be obtained through prior wind tunnel test data, computational fluid dynamics (CFD) simulations, or empirical models built based on flight data. Typically, Follow It increases as it increases.

[0074] For real-time estimation of rocket mass. To ensure the real-time accuracy of mass information, it can be provided by an onboard mass estimation algorithm.

[0075] This is the acceleration due to gravity.

[0076] This represents the rocket's current trajectory inclination. The calculation method can be found in CN119598066A, a generalized method for calculating launch vehicle trajectories.

[0077] For the real-time velocity of the rocket under landing system, i.e. .

[0078] The theoretical mass of the rocket at the nominal startup moment is the mass of the rocket at the expected startup altitude based on the mission design trajectory.

[0079] The theoretical velocity of the rocket at the nominal startup moment corresponds to The speed at that time.

[0080] The nominal startup altitude is the expected starting altitude of the engine's reverse thrust on the mission's designed trajectory.

[0081] In this embodiment, prediction This allows for a more precise consideration of the delay and transition process from the issuance of the ignition command to the full establishment of thrust, rather than simply assuming that thrust reaches its rated value instantaneously. This is particularly significant during the short period at the end of landing. Furthermore, during flight, online parameter identification technology can be used to correct uncertain parameters in the energy model in real time, such as engine specific impulse, thrust coefficient, and aerodynamic drag coefficient, thus ensuring... The predictions are closer to the actual situation.

[0082] Furthermore, throughout the entire power-on decision window ( Within the range, continuously monitor the rocket's current altitude. And the theoretical boot height calculated in real time And combined with preset security thresholds ( Make a decision to activate the rocket and determine its current altitude. Does the main control unit meet the power-on requirements? (At the rocket's current altitude...) The system will immediately instruct the engine to ignite and start when both of the following conditions are met; otherwise, it will continue with the engine start-up decision.

[0083] Specifically, this embodiment also monitors the rocket's current altitude. Has the theoretical startup height been reached or fallen below? and the rocket's current altitude Is it at the installation threshold? Make a judgment.

[0084] 1) Altitude determination: Current altitude during the rocket's descent and landing process. Reaching or falling below the theoretical power-on height calculated online It can be done through the formula: Make a judgment, among which It is a small positive number used to account for calculation and measurement errors. If This indicates that the rocket has entered the optimal ignition altitude range for fuel, and the altitude condition has been met.

[0085] 2) Safety assessment: To avoid premature or delayed ignition of the rocket engine, the ignition timing must be strictly controlled to ensure the rocket's current altitude is maintained. Not exceeding the maximum allowed boot height And not lower than the minimum backup power-on height. ,Right now < ≤ At that time, the safety conditions were met.

[0086] Once both of the above conditions are met simultaneously, the system immediately sends an ignition command to the engine and records this moment as the actual start-up time. The safety judgment condition in this embodiment is a hard safety constraint, even if it is affected by model changes or external disturbances. This prevents situations from occurring prematurely and avoids ignition at excessively high, unsafe altitudes, thus preventing unnecessary fuel waste and potential flight risks.

[0087] Furthermore, determine the rocket's current altitude. The method to determine if the main control system startup conditions are met is as follows: simultaneously check whether the rocket's current altitude has reached or fallen below the theoretical startup altitude, and whether the rocket's current altitude is within the installation threshold. To make a judgment; if the rocket's altitude during the descent and landing process... Reaching or falling below the theoretical power-on height calculated online ,and < ≤ If the ignition command is successfully sent, the guidance system will immediately send an ignition command to the rocket engine controller and record the moment the ignition command is sent as the actual start-up time; otherwise, it will continue to make a start-up decision.

[0088] The reusable rocket landing phase start-up altitude prediction method in this embodiment employs online real-time calculation, continuously and dynamically updating the predicted start-up altitude and decision conditions based on the rocket's current flight status (provided by sensors such as IMU and GPS), rather than relying on preset offline data or nominal trajectories. This enables the invention to effectively address various aerodynamic uncertainties, engine performance deviations, mass estimation errors, and other complex uncertainties present in actual flight, ensuring the accuracy and reliability of start-up timing.

[0089] Furthermore, the reusable rocket landing phase start-up altitude prediction method of this embodiment also has a backup start-up mechanism, which simultaneously checks whether the rocket's current altitude has reached or fallen below the theoretical start-up altitude, and whether the rocket's current altitude is within the installation threshold. During the judgment process, if the main control power-on condition is not triggered, once the rocket's current altitude... Down to The system will forcibly instruct the engine to start. That is, if for any reason (e.g., prediction model bias) causes... Inaccurate calculations, sensor malfunctions causing distorted altitude or velocity measurements, strong external disturbances leading to severe trajectory deviations, or internal system malfunctions preventing the main control system's startup logic from triggering properly (resulting in the main control system failing to meet startup conditions within the predetermined decision-making period, once the rocket's current altitude...) Descend to the preset backup power-on height limit The system will then forcefully instruct the engine to start. This serves as a final safety measure to prevent the rocket from crashing into the ground, ensuring that even in an emergency, the rocket can activate retro-rockets to slow down, maximizing mission safety.

[0090] The reusable rocket landing phase start-up altitude prediction method in this embodiment combines online energy prediction with dual safety thresholds. This invention significantly enhances the accuracy, robustness, and safety of determining the engine activation timing for the landing phase of a reusable liquid oxygen-methane rocket, providing a reliable solution for optimal fuel-efficient and precise landing.

[0091] In any of the above embodiments, backup power-on not only depends on altitude, but can also introduce other key parameters (such as excessive remaining speed, too close to the ground, abnormal falling acceleration, etc.) as collaborative triggering conditions to form a multi-source backup intelligent safety protection mechanism.

[0092] Furthermore, It is set at the highest point where the rocket can actually safely perform retro-thrust deceleration; It is set at the lowest point that allows the rocket to safely decelerate to zero within the remaining distance after ignition.

[0093] Furthermore, it can be dynamically adjusted based on environmental parameters. and The safety boundary of the startup decision window can no longer be a fixed value, but can be dynamically adjusted based on environmental and state parameters such as real-time atmospheric density, wind speed, wind direction, and rocket mass estimation error. For example, when the wind speed is high or the uncertainty of the mass estimation is high, the safety window can be appropriately expanded, or the lower limit can be adjusted to reserve more margin.

[0094] In any of the above embodiments, The value can range from 0.3m to 1m.

[0095] Furthermore, the reusable rocket landing phase start-up altitude prediction method in this embodiment also accurately incorporates the thrust-induced aerodynamic disturbance caused by the retro-thrust plume after engine start-up. Thrust-induced aerodynamic disturbance force Based on the real-time velocity of the rocket under the aforementioned landing system Dynamic corrections are made, and the values ​​are obtained from wind tunnel test data, computational fluid dynamics simulations, or empirical models. The introduction of this technology compensates for the shortcomings of traditional aerodynamic models that only consider the incoming flow resistance, making the start-up height prediction more consistent with the actual physical conditions and significantly improving the physical accuracy and precision of the prediction.

[0096] The reusable rocket landing phase engine start-up altitude prediction method in this embodiment effectively solves the accuracy and robustness issues of reusable liquid oxygen-methane rocket engine start-up timing under uncertain environments through the multi-level, multi-dimensional online prediction and safety assurance mechanisms in any of the above embodiments. It not only optimizes fuel consumption but also maximizes the safety of the rocket landing process through a dual safety threshold design, thereby significantly improving the success rate and economic benefits of reusable rocket landing missions.

[0097] The above embodiments can be combined with each other and have corresponding technical effects.

[0098] Another aspect of the present invention provides a guidance system, comprising at least: a preset module, a measurement module, a calculation module, a decision module, and a control module. The preset module is used to define the power-on decision window (…). ), and construct a system for calculating the theoretical boot height. The energy balance equation. The measurement module is used to monitor the rocket's current altitude. Thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances, etc. The calculation module is used to calculate the rocket's current trajectory inclination in real time. And based on the rocket's current trajectory inclination obtained in real time. Theoretical calculation of thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbance force at startup height. The decision module is used to compare the rocket's current altitude. Compared with the theoretical start-up height And combined with preset security thresholds ( The control module receives the start-up command from the decision module and controls the engine ignition. Through precise modeling and online solution of the energy balance, this method can predict the optimal start-up altitude for fuel. This means the rocket will ignite precisely at the moment retro-propulsion is needed, consuming no extra fuel and significantly improving the economics of reusable rockets.

[0099] The precise activation timing in this embodiment provides a reliable starting point and better initial conditions for subsequent guidance law and thrust adjustment, making the control process of the entire landing phase smoother and more efficient, and reducing the pressure on terminal attitude control and landing point correction.

[0100] The present invention also provides a processor for executing the steps in the reusable rocket landing phase start-up altitude prediction method in any of the above embodiments.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the starting altitude of a reusable rocket landing phase, characterized in that, At least the following steps are included: Define the boot decision window ( ), and ( Set as a safety threshold. To allow a maximum boot height, To ensure the minimum startup height; Based on the principle of energy conservation, construct a system that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. ; At the end of the rocket's aerodynamic deceleration phase, the rocket enters the activation decision window. After that, the current trajectory inclination angle of the rocket is calculated online. And based on the rocket's current trajectory inclination obtained in real time. Calculate the theoretical startup height ; Throughout the boot decision window ( Within the system, the rocket's current altitude is continuously monitored. And the theoretical boot height calculated in real time And combined with preset security thresholds ( Make the power-on decision; During the startup decision-making process, the current altitude of the rocket is determined. If the main control system meets the start-up conditions, the system will immediately instruct the engine to ignite and start up; otherwise, the start-up decision will continue. Among them, the thrust-induced aerodynamic disturbance force Based on the real-time velocity of the rocket in the landing system Dynamic corrections are made, and the values ​​are obtained from wind tunnel test data, computational fluid dynamics simulations, or empirical models.

2. The method for predicting the starting altitude of the reusable rocket landing segment according to claim 1, characterized in that, The determination of the rocket's current altitude The method to determine if the main controller's power-on conditions are met is as follows: At the same time, it is necessary to check whether the rocket's current altitude has reached or fallen below the theoretical startup altitude, and whether the rocket's current altitude is within the installation threshold. Make a judgment; If the rocket's altitude during its descent and landing process Reaching or falling below the theoretical power-on height calculated online ,and < ≤ If the ignition command is successfully sent, the guidance system will immediately send an ignition command to the rocket engine controller and record the moment the ignition command is sent as the actual start-up time; otherwise, it will continue to make a start-up decision.

3. The method for predicting the starting altitude of the reusable rocket landing section according to claim 2, characterized in that, The rocket entered the power-on decision window. After that, the current trajectory inclination angle of the rocket is calculated online. The method is as follows: The guidance system obtains the rocket's real-time velocity vector in the landing coordinate system from the onboard navigation system at a high frequency. Through the formula: The current trajectory inclination of the rocket was calculated. ;in, Let X be the horizontal X-axis velocity component of the rocket in the landing frame. Let be the velocity component of the rocket along the vertical Y-axis in the landing frame. Let be the horizontal velocity component of the rocket along the Z-axis in the landing system.

4. The method for predicting the starting altitude of the reusable rocket landing segment according to claim 3, characterized in that, Based on the principle of energy conservation, a system is constructed that at least covers the ballistic inclination angle. The energy balance equations for thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances are used to calculate the theoretical optimal start-up altitude for fuel in real time using analytical methods. The method is as follows: According to the energy balance equation: Real-time prediction of the optimal theoretical startup height ; in, Standard startup thrust; For thrust-induced aerodynamic disturbance force; To provide real-time mass estimation for the rocket; It is the acceleration due to gravity; This is the rocket's current trajectory inclination angle; For the real-time velocity of the rocket under landing system, i.e. ; The theoretical mass of the rocket at the nominal startup moment; The theoretical velocity of the rocket at the nominal startup moment corresponds to The speed at that time; This refers to the nominal startup height.

5. The method for predicting the starting altitude of the landing phase of a reusable rocket according to claim 4, characterized in that, During the decision-making process for powering on, the rocket's current altitude is determined. Reaching or falling below the theoretical power-on height calculated online The method is as follows: Through the formula: Make a judgment where 0.3m≤ ≤1m, used to handle calculation and measurement errors.

6. The method for predicting the starting altitude of the landing phase of a reusable rocket according to claim 2, characterized in that, Simultaneously, it is necessary to check whether the rocket's current altitude has reached or fallen below the theoretical startup altitude, and whether the rocket's current altitude is within the installation threshold. During the judgment process, if the main control power-on condition is not triggered, once the rocket's current altitude... Down to The system will then forcefully instruct the engine to start.

7. The method for predicting the starting altitude of the reusable rocket landing segment according to claim 1, characterized in that, The The setting is at the highest point where the rocket can actually safely perform retro-rockets deceleration; It is set at the lowest point that allows the rocket to safely decelerate to zero within the remaining distance after ignition.

8. A guidance system for implementing the reusable rocket landing phase start-up altitude prediction method according to any one of claims 1 to 7, characterized in that, At least including: Preset module, used to define the boot decision window ( ), and construct a system for calculating the theoretical boot height. The energy balance equation; The measurement module is used to monitor the rocket's current altitude. Thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbances; The calculation module is used to calculate the rocket's current trajectory inclination in real time. And based on the rocket's current trajectory inclination obtained in real time. Theoretical calculation of thrust, gravity, real-time mass, real-time velocity, and thrust-induced aerodynamic disturbance force at startup height. ; The decision module is used to compare the rocket's current altitude. Compared with the theoretical start-up height And combined with preset security thresholds ( Make the power-on decision; The control module is used to receive the power-on command from the decision module and control the engine to ignite and start.

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