A method for activating the vertical recovery and landing section of a rocket's first stage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING LANDSPACETECH CO LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-06-30
AI Technical Summary
The existing engine activation strategy for the vertical recovery landing stage of the first stage of reusable rockets relies on the nominal trajectory, which has poor adaptability, large computational load, or strong subjective judgment, making it difficult to balance recovery success rate, propellant economy, and engineering practicality.
Based on the maximum permissible start-up altitude and real-time flight status parameters, a one-dimensional vertical motion thrust calculation model is constructed. By comparing the required thrust with a preset threshold, a fixed-altitude start-up mechanism is adopted to achieve accurate determination of the start-up timing.
It improves the success rate of rocket precise landing and fuel economy, reduces propellant consumption, simplifies the start-up strategy control logic, is highly adaptable, requires less computation, and meets the needs of practical engineering applications.
Smart Images
Figure CN122041671B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of reusable rocket recovery technology, and particularly relates to a method for activating the vertical recovery and landing section of a rocket's first stage. Background Technology
[0002] When a reusable rocket's first stage performs a vertical recovery mission, it undergoes two engine ignition phases. The landing phase, as the last critical stage involving the engine, directly determines the success or failure of the recovery mission through its ignition strategy. Improper timing of ignition can not only significantly increase propellant consumption and reduce recovery economics, but may also cause the rocket's attitude, velocity, and other states at the moment of ignition to exceed the feasible range for powered landing, ultimately leading to recovery failure.
[0003] In existing technologies, the triggering mechanism for determining the engine start-up timing in this stage is mostly based on a single state quantity, such as timing triggering or altitude triggering. More complex schemes use comprehensive characteristic quantities such as mechanical energy and specific mechanical energy for judgment. The core implementation method is: the rocket calculates the characteristic quantity deviation between the current flight state and the nominal trajectory start-up point online; when this deviation approaches zero, the engine is triggered to start. While this type of start-up method is logically simple and easy to implement, it has significant drawbacks: on the one hand, it is difficult to guarantee the optimality of the start-up point, resulting in propellant waste during the landing phase; on the other hand, it relies excessively on a preset nominal trajectory, lacking adaptability to trajectory deviations and disturbances that occur during flight, and exhibiting weak anti-interference capabilities.
[0004] To overcome the shortcomings of the aforementioned single / simple integrated feature-based activation methods, existing technologies have proposed hybrid activation strategies that partially integrate multiple flight feature quantities. However, these strategies still have technical limitations, specifically: 1. In Chinese invention patent application CN112660426A, "A Rocket Soft Landing Guidance Method," activation determination is achieved by solving the optimal fuel trajectory optimization problem. While this method can consider fuel economy, the optimization computation is large, requiring high computing power from the onboard computer, and the real-time performance and reliability of online applications cannot meet actual engineering needs. 2. In Chinese invention patent application CN112525004A, "Online Determination Method and System for Activation Point of Rocket Fixed-Point Soft Landing," a hybrid activation strategy is constructed based on two feature quantities: equal-altitude velocity deviation and equal-altitude horizontal position deviation. The deviation relative to the nominal activation point height is determined through a saturation function. This method still relies excessively on the nominal trajectory, and the parameter selection of the saturation function is somewhat subjective, lacking clear engineering design basis, which easily leads to insufficient accuracy in activation timing determination.
[0005] In summary, existing engine activation strategies for the landing stage of reusable rockets generally suffer from problems such as reliance on nominal trajectories, poor adaptability, high computational load, or strong subjectivity in decision-making, making it difficult to balance recovery success rate, propellant economy, and engineering practicality. Therefore, there is an urgent need for an engine activation strategy that balances adaptability, economy, and real-time performance to improve the success rate of rocket precision landing and fuel economy. Summary of the Invention
[0006] The present invention aims to provide a method for starting up the engine of the vertical recovery and landing section of a rocket's first stage, so as to solve the technical defects of the existing engine start-up strategy for the vertical recovery and landing section of a reusable rocket's first stage.
[0007] The first aspect of this invention provides a method for activating the vertical recovery and landing section of a rocket's first stage, comprising:
[0008] The maximum allowable thrust of the engine is determined based on the engine operating mode of the vertical recovery and landing section of the first stage of the rocket, and the engine start-up decision window is determined based on the nominal trajectory and simulation results.
[0009] Based on the engine start-up decision window, a maximum permissible start-up altitude is set, and based on the maximum permissible start-up altitude, a landing phase start-up determination is made to complete the start-up of the vertical recovery and landing phase of the rocket's first stage.
[0010] Real-time acquisition of flight status parameters for the current landing segment, including current flight altitude, vertical descent speed, and rocket mass;
[0011] In each startup determination cycle, if the current flight altitude is lower than the maximum allowable startup altitude, a one-dimensional vertical motion thrust calculation model is constructed based on the rocket body mass and the maximum allowable thrust of the engine to obtain the required thrust for startup under the current flight state. At the same time, a preset threshold for the fixed-altitude startup altitude is determined based on the vertical descent speed.
[0012] Within each engine start-up determination cycle, the required thrust is compared with the preset thrust threshold in real time: if the required thrust is determined to be greater than or equal to the preset thrust threshold, the engine start-up command is immediately triggered to complete the characteristic quantity start-up; otherwise, if the engine start-up is not triggered within the engine start-up decision window, the engine start-up at altitude is triggered when the current flight altitude drops to the preset threshold of the altitude hold start-up altitude.
[0013] In some embodiments, determining the maximum permissible thrust of the engine based on the engine operating mode of the rocket's first-stage vertical recovery and landing phase includes:
[0014] The engine operating mode of the vertical recovery and landing section of the first stage of the rocket is set to switch the number of engine operating points at most once:
[0015] If the number of engine working stations is switched once, the time of switching the number of engine working stations is set as the dividing point, and the landing segment is divided into the first working stage and the second working stage.
[0016] The maximum permissible thrust of the engine in the first operating phase and the second operating phase are respectively denoted as... and ;
[0017] If there is no scenario requiring switching of the number of engine workstations, then ;
[0018] The maximum permissible thrust of the engine is determined to be .
[0019] In some embodiments, the step of constructing a one-dimensional vertical motion thrust calculation model based on the rocket body mass and the engine's maximum permissible thrust to obtain the required thrust for startup under the current flight state includes:
[0020] One-dimensional vertical motion accelerations for the first and second working stages are established based on the optimal fuel thrust profile.
[0021] The calculation equations for the rocket terminal velocity, terminal position, and transition phase height are obtained by integrating the one-dimensional vertical motion acceleration.
[0022] The equations for calculating the rocket terminal velocity, terminal position, and transition stage height are combined to form a three-dimensional nonlinear equation system; wherein, the three-dimensional nonlinear equation system becomes a two-dimensional nonlinear equation system in the scenario where the number of engine working platforms does not change.
[0023] The three-dimensional or two-dimensional nonlinear equations are solved using LM to obtain the required thrust for startup under the current flight conditions.
[0024] In some embodiments, establishing the one-dimensional vertical motion acceleration for the first and second working stages based on the optimal fuel thrust profile includes:
[0025] The thrust values for the first and second operating stages are determined based on the maximum permissible thrust of the engine in the first and second operating stages, respectively.
[0026] The one-dimensional vertical motion acceleration of the first working stage is obtained based on the rocket body mass and the thrust value of the first working stage, and the one-dimensional vertical motion acceleration of the second working stage is obtained based on the rocket body mass and the thrust value of the second working stage.
[0027] In some embodiments, the one-dimensional vertical acceleration of the first working phase is obtained based on the rocket body mass and the thrust value of the first working phase, and the one-dimensional vertical acceleration of the second working phase is obtained based on the rocket body mass and the thrust value of the second working phase, and the formulas are expressed as follows:
[0028] ;
[0029] ;
[0030] in, This refers to the one-dimensional vertical motion acceleration during the first working phase. This refers to the one-dimensional vertical motion acceleration during the second working phase. This is the thrust value for the first working stage. This is the thrust value for the second working stage. The duration of the first working phase. The duration of the second working phase, The mass of the arrow body, This refers to the specific impulse of the engine. It is the acceleration due to gravity. t This refers to the engine's operating time.
[0031] In some embodiments, determining the preset threshold for the fixed-height start-up height based on the vertical descent speed includes:
[0032] The rocket is set to decelerate at the estimated maximum thrust during the landing phase;
[0033] Based on the estimated maximum thrust state of the landing phase, the minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis.
[0034] The minimum displacement is determined as a preset threshold for the fixed-height start-up height.
[0035] In some embodiments, the minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis, and the calculation formula is as follows:
[0036] ;
[0037] in, This represents the estimated maximum thrust acceleration during the landing phase. The minimum displacement is the preset threshold value for the fixed-height start-up height. The vertical descent velocity, This is the acceleration due to gravity.
[0038] In some embodiments, the formula for calculating the estimated maximum thrust acceleration during the landing phase is as follows:
[0039] ;
[0040] The maximum permissible thrust of the engine mentioned above , To the maximum permissible propellant mass consumed during the landing phase, Let be the mass of the arrow body.
[0041] A second aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method described in the above embodiments.
[0042] A third aspect of the present invention provides a computer program product, including a computer program / instructions, which, when executed by a processor, implements the steps of the method described in the above embodiments.
[0043] This invention provides a method for activating the vertical recovery landing section of a rocket's first stage. This method determines the activation of the landing section based on the maximum permissible activation altitude, calculates the required thrust by collecting rocket flight status parameters in real time, and completes the accurate determination of the activation timing. At the same time, it adds an altitude-permissible activation setting, using fixed-altitude activation as a reliable activation measure, thus achieving both accuracy and reliability in activation determination. Attached Figure Description
[0044] Figure 1 This is a flowchart illustrating the activation method of the vertical recovery and landing section of the first stage of a rocket according to an embodiment of the present invention.
[0045] Figure 2 This is a flowchart of the landing and power-on determination calculation according to an embodiment of the present invention. Detailed Implementation
[0046] Various embodiments and features of this application are described herein with reference to the accompanying drawings.
[0047] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.
[0048] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.
[0049] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.
[0050] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.
[0051] The present invention aims to solve the technical defects of the existing engine start-up strategy for the vertical recovery landing stage of the first stage of reusable rockets. Specifically, it includes: (1) Existing single state quantity triggering or simple comprehensive characteristic quantity discrimination strategies rely too much on the nominal trajectory, are not adaptable to flight trajectory deviations and external disturbances, have weak anti-interference capabilities, and are prone to causing the rocket state to exceed the feasible domain of powered landing at the start-up time; (2) The fuel-optimal start-up discrimination method based on online optimization strategy has a large computational load and requires high computing power from the onboard computer, making it difficult to meet the real-time and reliability requirements of online applications; (3) The parameter selection in the hybrid characteristic quantity start-up strategy is subjective, lacks clear engineering design basis, has insufficient accuracy in judging the start-up time, and cannot take into account both propellant economy and recovery reliability.
[0052] Based on this, the core objective of this invention is to provide an engine start-up strategy that is independent of nominal trajectory, has low computational load, strong adaptability, and high discrimination accuracy, effectively reducing propellant consumption, improving the success rate and control accuracy of rocket precise landing, and meeting the needs of practical engineering applications.
[0053] Figure 1 This is a flowchart illustrating a startup method for the vertical recovery and landing section of a rocket's first stage, provided as an embodiment of the present invention. Figure 1 As shown, a method for activating the vertical recovery and landing section of a rocket's first stage includes the following steps:
[0054] S101 determines the maximum allowable thrust of the engine based on the engine operating mode of the vertical recovery and landing section of the first stage of the rocket, and determines the engine start-up decision window based on the nominal trajectory and simulation results.
[0055] Specifically, the landing phase engine operating mode is confirmed as follows: First, the preset operating mode of the landing phase engine is determined, and it is determined whether there is a switch in the number of operating engines (this invention only considers at most one switch). The engine operating configuration is locked to provide a basis for subsequent thrust calculation and engine start-up determination. Simultaneously, the engine start-up decision window is defined: The landing phase engine start-up decision window is delineated, and the permissible start-up altitude is clearly defined. Only when the rocket is below the permitted startup altitude can the subsequent startup determination process be initiated, thus avoiding the risk of premature engine startup due to accidental triggering and propellant waste.
[0056] S102, based on the engine start-up decision window, set the maximum allowable start-up altitude, and based on the maximum allowable start-up altitude, determine the start-up of the landing segment to complete the start-up of the vertical recovery landing segment of the first stage of the rocket.
[0057] Specifically, the core of the boot decision window is to define the allowed boot height. Initially, the starting altitude is based on the nominal ballistic theory. Preset a fixed ratio for increasing or decreasing, such as... Subsequently, based on flight deviations and mathematical simulation results, iterative adjustments are made to ensure that the aircraft operates within the upper limit of the permissible operating altitude. Internally, once the main power-on detection mechanism is triggered, it can stably achieve a precise soft landing of the first stage in conjunction with subsequent guidance and control algorithms.
[0058] S103, real-time acquisition of current landing segment flight status parameters, including current flight altitude, vertical descent speed and rocket mass.
[0059] S104, in each startup determination cycle, if the current flight altitude is lower than the maximum allowable startup altitude, a one-dimensional vertical motion thrust calculation model is constructed based on the rocket body mass and the maximum allowable thrust of the engine to obtain the required thrust for startup under the current flight state. At the same time, a preset threshold for the fixed-altitude startup altitude is determined based on the vertical descent speed.
[0060] Specifically, the calculation of required thrust and altitude hold-start altitude is as follows: Using the rocket navigation system and online mass estimation system, filtered core flight status parameters (including current flight altitude) for the landing phase are collected at fixed intervals (e.g., 20ms, which is the start-up judgment calculation interval; the specific interval should be determined based on the real-time performance of the required thrust calculation module on the rocket). Vertical descent speed and the mass of the arrow body Then, based on the one-dimensional vertical motion fuel-optimal thrust profile and combined with Newton's laws of motion, a thrust calculation model is constructed to calculate the required thrust for achieving fuel-optimal landing under the current flight conditions. Simultaneously, assuming the rocket decelerates at full thrust, the minimum displacement required to decelerate from the current speed to zero is estimated through dynamic analysis, and the set altitude for launch is determined accordingly. This provides a quantitative basis for setting up a backup mechanism.
[0061] S105, within each startup determination cycle, the required thrust is compared with the preset thrust threshold in real time: if the required thrust is determined to be greater than or equal to the preset thrust threshold, the engine startup command is immediately triggered to complete the characteristic quantity startup; otherwise, if the engine startup is not triggered within the engine startup decision window, the engine startup is triggered when the current flight altitude drops to the preset threshold of the altitude hold startup altitude.
[0062] Specifically, power-on detection: preset thrust threshold The value is the maximum thrust that the engine can provide. The thrust is set at 80% to 90%. This value ensures sufficient thrust to counteract the vertical descent velocity and achieve a smooth landing after startup, while also reserving a 10% to 20% thrust adjustment margin to cope with subsequent trajectory deviations and external disturbances. Simultaneously, it balances optimal propellant consumption with landing reliability. During the startup determination calculation cycle, the required thrust is calculated in real time. With preset threshold The comparison, if determined The engine start command is immediately triggered. Simultaneously, a high-backup start mechanism is added as a redundancy guarantee for the primary mechanism. If the primary mechanism fails to trigger within the start decision window, and the rocket descends to the preset high start altitude... At that time, the engine is forcibly started, which can provide some deceleration even if the main mechanism fails, increasing the probability of successful recovery or at least reducing the degree of damage.
[0063] Compared with the prior art, the technical solution of this invention determines the start-up of the landing phase based on the maximum allowable start-up altitude. It calculates the required thrust by collecting rocket flight status parameters in real time to accurately determine the start-up timing. At the same time, it adds an altitude-allowed start-up and uses fixed-altitude start-up as a reliable start-up measure, thus achieving both accuracy and reliability in start-up determination.
[0064] It can be seen that the present invention constructs a thrust calculation model based on a one-dimensional vertically moving fuel optimal thrust profile, combined with the engine's maximum thrust. Using 80% to 90% as a threshold, a fuel-optimal start-up timing control logic is formed, breaking through the bottleneck of propellant waste in traditional strategies and achieving precise optimization of fuel economy in the landing phase. Simultaneously, the start-up strategy control architecture is simplified, focusing on one-dimensional vertical motion parameter processing, eliminating the need for complex multi-dimensional trajectory planning algorithms. While ensuring real-time performance and stability, it can be directly adapted to existing onboard hardware computing power, reducing engineering implementation and technology transfer costs, and balancing practicality and economy.
[0065] Based on the above embodiments, determining the maximum permissible thrust of the engine based on the engine operating mode of the rocket's first-stage vertical recovery and landing section includes:
[0066] The engine operating mode of the vertical recovery and landing section of the first stage of the rocket is set to switch the number of engine operating points at most once:
[0067] If the number of engine working stations is switched once, the time of switching the number of engine working stations is set as the dividing point, and the landing segment is divided into the first working stage and the second working stage.
[0068] The maximum permissible thrust of the engine in the first operating phase and the second operating phase are respectively denoted as... and ;
[0069] If there is no scenario requiring switching of the number of engine workstations, then ;
[0070] The maximum permissible thrust of the engine is determined to be .
[0071] Specifically, the maximum permissible thrust is determined based on the engine operating mode during the landing phase. To ensure landing safety, the number of operating engines in the landing phase of a reusable rocket typically needs to be adjusted. This invention adapts to the common engineering scenario of "at most one engine operating number switch." To ensure consistency between thrust calculation and engine activation judgment logic, the landing phase is divided into two operating phases, with the engine operating number switch moment as the dividing point: the maximum total thrust that the engines can provide in the first phase is... The maximum total thrust that the engine can provide during the second stage is For scenarios where there is no engine switching during the landing phase, visual... .
[0072] Based on the above embodiments, the step of constructing a one-dimensional vertical motion thrust calculation model based on the rocket body mass and the engine's maximum permissible thrust to obtain the required thrust for engine activation under the current flight state includes:
[0073] One-dimensional vertical motion accelerations for the first and second working stages are established based on the optimal fuel thrust profile.
[0074] The calculation equations for the rocket terminal velocity, terminal position, and transition phase height are obtained by integrating the one-dimensional vertical motion acceleration.
[0075] The equations for calculating the rocket terminal velocity, terminal position, and transition stage height are combined to form a three-dimensional nonlinear equation system; wherein, the three-dimensional nonlinear equation system becomes a two-dimensional nonlinear equation system in the scenario where the number of engine working platforms does not change.
[0076] The three-dimensional or two-dimensional nonlinear equations are solved using LM to obtain the required thrust for startup under the current flight conditions.
[0077] Specifically, when the rocket's flight altitude is below the allowable activation altitude, during each activation determination cycle, the current flight altitude is collected in real time. Vertical descent speed Arrow body mass A thrust calculation method based on a one-dimensional vertical motion model is used to estimate the initial thrust required for immediate startup under the current conditions. This thrust calculation method based on the one-dimensional vertical motion model is detailed below: First, considering one-dimensional vertical motion, a design is constructed as follows... The optimal thrust profile of bang-bang fuel, where , Let $\mathbf$ and $\mathbf$ represent the thrust magnitudes during the first and second operational phases of the landing segment, respectively, both being constant values. Based on this, the following one-dimensional vertical motion equation is established.
[0078] For the first working phase, the acceleration is:
[0079] ;
[0080] For the second working phase, the acceleration is:
[0081] ;
[0082] in, This refers to the one-dimensional vertical motion acceleration during the first working phase. This refers to the one-dimensional vertical motion acceleration during the second working phase. This is the thrust value for the first working stage. This is the thrust value for the second working stage. The duration of the first working phase. The duration of the second working phase, The mass of the arrow body, This refers to the specific impulse of the engine. Let gravitational acceleration be a constant value. t This refers to the engine's operating time.
[0083] remember By integrating the above acceleration, the terminal velocity of the rocket can be derived. Terminal location and transition phase height The calculation equation is as follows:
[0084] ;
[0085] In the formula , These are all intermediate quantities used in the derivation of the above formulas. This is the thrust value for the first working stage. This is the thrust value for the second working stage. The duration of the first working phase. The duration of the second working phase, The mass of the arrow body, This refers to the specific impulse of the engine. Let gravitational acceleration be a constant value. Current flight altitude The vertical descent velocity, This represents the natural logarithm function.
[0086] From a fuel-optimal perspective, the thrust configuration for the second stage should ideally be close to the maximum available thrust. However, to balance the landing thrust adjustment margin with the horizontal thrust distribution requirements, a different approach was taken. Combined with the given terminal velocity, position, and transition stage height... The above equations, when combined, form a system containing three unknowns. , and The nonlinear equation system:
[0087] ;
[0088] in, , F ( y ) represents information about the variable y The system of equations contains three scalar equations. In actual calculations, the terminal velocity... ,Location Take the actual target landing state value (usually 0). Based on actual engineering debugging settings, if the value is too small, although the engine start-up time can be delayed, it will significantly compress the working time of the second stage of the landing phase, resulting in insufficient adjustment margin for attitude and trajectory correction, ultimately failing to meet the control accuracy requirements of the landing phase. If the parameter value is too large, the engine start-up time will be too early, increasing fuel consumption and violating the optimal fuel design goal of the recovery mission. In particular, for scenarios where there is no engine operating number switching, the value should be set as follows: , The above three-dimensional nonlinear equation system degenerates into a system containing two unknowns. , Two-dimensional nonlinear equations:
[0089] ;
[0090] in, , G ( z ) represents the variable zThe system of equations contains two scalar equations. In actual calculations, the terminal velocity... ,Location Take the actual target landing state value (usually 0).
[0091] For the aforementioned three-dimensional / two-dimensional nonlinear equations, the robust Levenberg-Marquardt (LM) method can be used for fast and stable solutions. The initial values for iteration are determined based on the nominal ballistic design results. This refers to the thrust required to start the machine in the current state. .
[0092] Based on the above embodiments, the step of establishing one-dimensional vertical motion accelerations for the first and second working stages based on the optimal fuel thrust profile includes:
[0093] The thrust values for the first and second operating stages are determined based on the maximum permissible thrust of the engine in the first and second operating stages, respectively.
[0094] The one-dimensional vertical motion acceleration of the first working stage is obtained based on the rocket body mass and the thrust value of the first working stage, and the one-dimensional vertical motion acceleration of the second working stage is obtained based on the rocket body mass and the thrust value of the second working stage.
[0095] Based on the above embodiments, the one-dimensional vertical acceleration of the first working stage is obtained based on the rocket body mass and the thrust value of the first working stage, and the one-dimensional vertical acceleration of the second working stage is obtained based on the rocket body mass and the thrust value of the second working stage, and the formulas are expressed as follows:
[0096] ;
[0097] ;
[0098] in, This refers to the one-dimensional vertical motion acceleration during the first working phase. This refers to the one-dimensional vertical motion acceleration during the second working phase. This is the thrust value for the first working stage. This is the thrust value for the second working stage. The duration of the first working phase. The duration of the second working phase, The mass of the arrow body, This refers to the specific impulse of the engine. It is the acceleration due to gravity. t This refers to the engine's operating time.
[0099] Based on the above embodiments, the preset threshold for determining the fixed-height start-up height based on the vertical descent speed includes:
[0100] The rocket is set to decelerate at the estimated maximum thrust during the landing phase;
[0101] Based on the estimated maximum thrust state of the landing phase, the minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis.
[0102] The minimum displacement is determined as a preset threshold for the fixed-height start-up height.
[0103] It should be noted that the method for determining the fixed-height startup height parameter is as follows: Fixed-height startup is used as a backup startup strategy, starting at a preset fixed height. Automatic engine ignition triggering threshold The calculation is as follows:
[0104] ;
[0105] in The maximum thrust acceleration that can be provided for the estimated landing segment is calculated as follows:
[0106] ;
[0107] In the formula , The maximum permissible mass of propellant consumed during the landing segment is determined by engineering constraints.
[0108] Based on the above embodiments, the minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis, and the calculation formula is as follows:
[0109] ;
[0110] in, This represents the estimated maximum thrust acceleration during the landing phase. The minimum displacement is the preset threshold value for the fixed-height start-up height. The vertical descent velocity, This is the acceleration due to gravity.
[0111] Based on the above embodiments, the formula for calculating the estimated maximum thrust acceleration during the landing phase is as follows:
[0112] ;
[0113] The maximum permissible thrust of the engine is mentioned above. , To the maximum permissible propellant mass consumed during the landing phase, Let be the mass of the arrow body.
[0114] In summary, compared with existing reusable rocket first-stage landing engine activation strategies, this invention achieves significant improvements in three core dimensions: fuel economy, discrimination accuracy, and operational reliability. It also possesses strong adaptability and scalability to various operating conditions. Specific beneficial effects are as follows:
[0115] (1) Significantly optimized fuel economy: The core of this invention is to construct a calculation model using a one-dimensional vertical motion fuel optimal thrust profile, accurately calculate the minimum thrust required to achieve a smooth landing, and combine it with the threshold setting of 80%~90% of the maximum thrust to adjust the start-up timing as needed, avoiding propellant waste caused by premature start-up.
[0116] (2) Improved accuracy of startup determination: This invention abandons the traditional startup mode triggered by a single state quantity or determined by a simple comprehensive feature quantity. By collecting the core flight state parameters after filtering in real time and combining them with the demand thrust calculation model, it achieves accurate determination of startup timing, which effectively improves the pain points of traditional strategies such as insufficient adaptability to flight trajectory deviation, external disturbances and weak anti-interference ability.
[0117] (3) Simplified control logic and low engineering implementation difficulty: The calculation process architecture of this invention is clear and the links are closely connected, without the need for complex multi-dimensional ballistic planning algorithms. The on-board calculation module only focuses on processing one-dimensional vertical motion parameters, with small calculation volume and strong real-time performance. It can be directly adapted to the existing on-board hardware computing power level without the need for additional high-performance computing components, taking into account both engineering feasibility and operational stability, and reducing the cost of technology transformation and large-scale application.
[0118] (4) Wide range of working conditions and strong scalability: This invention can be adapted to various recovery rocket models with up to one engine working number switch in the landing section. It can be ported and applied without major adjustments to the core logic, and has strong versatility and engineering expansion value.
[0119] Further improvements and modifications to the above technical solutions are also within the scope of protection of this invention, such as, but not limited to:
[0120] (1) Start-up judgment based on predicted state: The basic scheme of this invention is based entirely on the real-time collected current flight state parameters to make start-up judgment, ignoring the delay characteristics of the engine start-up process. The improved scheme can introduce engine start-up delay time correction to compensate for the time difference between the start-up command trigger and the stable output of thrust. Using the rocket body motion state prediction model, based on the currently collected flight parameters, the vertical velocity and altitude at the moment of stable thrust output are predicted. The required thrust value under the predicted state is calculated to realize the predictive triggering of the start-up time and further improve the engineering adaptability.
[0121] (2) Adding aerodynamic correction terms: The basic scheme of this invention ignores the influence of aerodynamic drag on the required thrust. The improved scheme can introduce an aerodynamic drag correction model, and combine the aerodynamic characteristics of the rocket body and the flight state to estimate the thrust compensation terms corresponding to the aerodynamic drag after landing and starting the engine; the required thrust is corrected and calibrated to improve the calculation accuracy of the required thrust under high Mach number and high aerodynamic drag conditions, and effectively broaden the applicability of this scheme.
[0122] (3) Adding a horizontal correction term: The basic scheme of this invention ignores the influence of horizontal position and velocity deviation on the start-up decision. The basic premise is that vertical motion is the main motion direction during the landing phase of flight. The improved scheme can add a horizontal correction term based on the real-time matching relationship between horizontal position and velocity. By collecting horizontal motion parameters through the navigation system, a horizontal-vertical linkage correction model is constructed, which converts the horizontal deviation into a fine adjustment amount of the required thrust discrimination threshold, thereby improving the accuracy of the landing start-up timing.
[0123] In some embodiments of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the method described in the above embodiments.
[0124] In some embodiments of the present invention, a computer program product is provided, including a computer program / instructions, which, when executed by a processor, implements the steps of the method described in the above embodiments.
[0125] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the methods in the above embodiments.
[0126] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).
[0127] Computer-readable storage media may also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.
[0128] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).
[0129] The processor can communicate with external devices via the I / O bus through wired or wireless networks.
[0130] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.
[0131] Those skilled in the art will understand that all or part of the steps of the methods described above can be implemented by a program instructing related hardware. The program can be stored in a readable storage medium, and when executed, the program includes one or a combination of the steps of the method implementation.
[0132] In the various embodiments of this application, the functional units can be integrated into a single processing module, or each unit can exist physically separately, or two or more units can be integrated into a single module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a readable storage medium. The storage medium can be a read-only memory, a disk, or an optical disk, etc.
[0133] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. Furthermore, the described specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments / modes or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.
[0134] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0135] Those skilled in the art should understand that the above embodiments are merely for illustrative purposes and are not intended to limit the scope of this application. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of this application.
Claims
1. A method for activating the vertical recovery and landing section of a rocket's first stage, characterized in that, include: The maximum permissible thrust of the engine is determined based on the engine operating mode of the rocket's first-stage vertical recovery and landing phase, including: The engine operating mode of the vertical recovery and landing section of the first stage of the rocket is set to switch the number of engine operating points at most once: If the number of engine working stations is switched once, the time of switching the number of engine working stations is set as the dividing point, and the landing segment is divided into the first working stage and the second working stage. The maximum permissible thrust of the engine in the first operating phase and the second operating phase are respectively denoted as... and ; If there is no scenario requiring switching of the number of engine workstations, then ; The maximum permissible thrust of the engine is determined to be ; The engine start-up decision window is determined based on the nominal trajectory and simulation results; Based on the engine start-up decision window, a maximum permissible start-up altitude is set, and based on the maximum permissible start-up altitude, a landing phase start-up determination is made to complete the start-up of the vertical recovery and landing phase of the rocket's first stage. Real-time acquisition of flight status parameters for the current landing segment, including current flight altitude, vertical descent speed, and rocket mass; Within each startup determination cycle, if the current flight altitude is lower than the maximum permissible startup altitude, a one-dimensional vertical motion thrust calculation model is constructed based on the rocket body mass and the engine's maximum permissible thrust to obtain the required thrust for startup under the current flight state, including: One-dimensional vertical motion accelerations for the first and second working stages are established based on the optimal fuel thrust profile. The calculation equations for the rocket terminal velocity, terminal position, and transition phase height are obtained by integrating the one-dimensional vertical motion acceleration. The equations for calculating the rocket terminal velocity, terminal position, and transition stage height are combined to form a three-dimensional nonlinear equation system; wherein, the three-dimensional nonlinear equation system becomes a two-dimensional nonlinear equation system in the scenario where the number of engine working platforms does not change. The three-dimensional or two-dimensional nonlinear equations are solved using LM to obtain the required thrust for startup under the current flight conditions. Simultaneously, a preset threshold for the fixed-height start-up height is determined based on the vertical descent speed; Within each engine start-up determination cycle, the required thrust is compared with the preset thrust threshold in real time: if the required thrust is determined to be greater than or equal to the preset thrust threshold, the engine start-up command is immediately triggered to complete the characteristic quantity start-up; otherwise, if the engine start-up is not triggered within the engine start-up decision window, the engine start-up at altitude is triggered when the current flight altitude drops to the preset threshold of the altitude hold start-up altitude.
2. The method according to claim 1, characterized in that, The establishment of one-dimensional vertical motion accelerations for the first and second working stages based on the optimal fuel thrust profile includes: The thrust values for the first and second operating stages are determined based on the maximum permissible thrust of the engine in the first and second operating stages, respectively. The one-dimensional vertical motion acceleration of the first working stage is obtained based on the rocket body mass and the thrust value of the first working stage, and the one-dimensional vertical motion acceleration of the second working stage is obtained based on the rocket body mass and the thrust value of the second working stage.
3. The method according to claim 2, characterized in that, The one-dimensional vertical acceleration of the first working stage is obtained based on the rocket body mass and the thrust value of the first working stage, and the one-dimensional vertical acceleration of the second working stage is obtained based on the rocket body mass and the thrust value of the second working stage. The formulas are expressed as follows: ； ； in, This refers to the one-dimensional vertical motion acceleration during the first working phase. This refers to the one-dimensional vertical motion acceleration during the second working phase. This is the thrust value for the first working stage. This is the thrust value for the second working stage. The duration of the first working phase. The duration of the second working phase, The mass of the arrow body, This refers to the specific impulse of the engine. It is the acceleration due to gravity. t This refers to the engine's operating time.
4. The method according to claim 1, characterized in that, The preset threshold for determining the fixed-height start-up height based on the vertical descent speed includes: The rocket is set to decelerate at the estimated maximum thrust during the landing phase; Based on the estimated maximum thrust state of the landing phase, the minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis. The minimum displacement is determined as a preset threshold for the fixed-height start-up height.
5. The method according to claim 4, characterized in that, The minimum displacement required to decelerate from the vertical descent velocity to zero is calculated through dynamic analysis, and the calculation formula is as follows: ； in, This represents the estimated maximum thrust acceleration during the landing phase. The minimum displacement is the preset threshold value for the fixed-height start-up height. The vertical descent velocity, This is the acceleration due to gravity.
6. The method according to claim 5, characterized in that, The formula for calculating the estimated maximum thrust acceleration during the landing phase is as follows: ； The maximum permissible thrust of the engine mentioned above , To the maximum permissible propellant mass consumed during the landing phase, Let be the mass of the arrow body.
7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the power-on method for the vertical recovery and landing section of the first stage of the rocket as described in any one of claims 1 to 6.
8. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the activation method for the vertical recovery and landing section of the first stage of a rocket as described in any one of claims 1 to 6.