CN-121976896-A - Reusable rocket landing zone fuel optimal thrust adjusting method, device and storage medium

CN121976896ACN 121976896 ACN121976896 ACN 121976896ACN-121976896-A

Abstract

A method for regulating fuel optimal thrust of reusable rocket landing section includes constructing energy upper limit index of one machine section as criterion of regulating thrust of three machine sections, continuously iterative calculation and regulating virtual throttle ratio of thrust of three machine sections to make energy upper limit index of one machine section meet preset threshold requirement and be as small as possible, combining current attitude angle of rocket based on optimized virtual throttle ratio obtained by iteration, carrying out space synthesis of thrust vector of three machine sections, carrying out calculation of thrust vector of one machine section and limiting limit of throttle ratio by iteration after one machine is turned into one machine. According to the method, based on the form of combining energy analysis and analysis iteration, the virtual throttle ratio of the thrust of the engine is regulated on line in real time, and the optimal thrust control of the fuel in the rocket landing process can be effectively completed by combining the thrust closed-loop control, so that the safe and accurate landing of the rocket is ensured.

Inventors

LI CHUNZHI
ZHONG YOUWU
CHEN SHUZHAO
Mi Wenhao
YU LEI
ZHANG CHANGWU
DAI ZHENG
ZHANG XIAODONG

Assignees

蓝箭航天空间科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20251209

Claims (10)

1. The optimal thrust adjusting method for the fuel of the reusable rocket landing zone is characterized by comprising the following steps of: S1, taking the upper limit of the energy of one machine section as a criterion for the thrust adjustment of three machine sections, namely, if the upper limit of the energy of one machine section is larger than a set threshold value, then, the energy of the three machine sections can be transited to the one machine section for safe landing, and searching the minimum three machine thrust meeting the landing requirement based on the energy of the three machine sections to realize the optimal fuel; s2, simplifying the motion of the three sections into vertical motion, taking the vertical throttling ratio as a virtual throttling ratio of the three sections, and continuously and iteratively calculating and adjusting the virtual throttling ratio of the thrust of the three sections based on the corresponding relation between the throttling ratio and the total thrust so that the upper energy limit of one section meets the preset threshold requirement and is as small as possible; And S3, synthesizing a three-section thrust vector space, namely converting the vertical thrust component into a thrust vector in a three-dimensional space based on the optimized virtual throttling ratio obtained by iteration and combining the current attitude angle of the rocket.
2. The method according to claim 1, wherein the calculation method of step S2 includes: by setting initial throttle ratio and utilizing the upper limit index of energy of one machine section Newton's iterative calculation is performed, in each iteration, according to Dynamically adjusting the current thrust virtual throttle ratio Until convergence to an optimal value.
3. The method according to claim 2, wherein the specific calculation method of step S2 includes: S21, pre-operation is performed once at the beginning of each guidance period: Virtual throttle ratio initialization at the beginning of the current guidance period The initial value of (1) is inherited from the calculation result of the previous guidance period: Wherein, the Representing a previous guidance cycle; S22, iterative operation, namely on-line adjustment of the virtual throttle ratio: Iterative calculation of a computer segment energy upper limit index And adjust the virtual throttle ratio accordingly The method comprises the following steps: 1) Calculating a computer section energy upper limit index The index represents the initial height of a machine section; 2) Updating virtual throttle ratio According to Dynamically adjusting the size and direction of (2) Wherein, the Step length is adjusted for a preset throttling ratio; = +setting constant, if Falls to Within the interval, the convergence or meeting the requirement, the circulation is jumped out, and at the same time, the method is suitable for Upper and lower limits of engine throttle ratio are performed And To ensure its physical feasibility; 3) Recording the result of this operation The initial value recorded as the next guidance period: ; And (5) iterating the loop, namely repeating the calculation until the condition of jumping out of the loop is met.
4.A method according to claim 3, wherein in step S2, the one-stage energy upper limit indicator is set The calculation method of (1) comprises the following steps: (1) Pre-operation, which is executed once before each iteration loop starts 1) Initializing state quantity, namely assigning an iteration initial value according to the real-time state of the rocket in the current guidance period: Wherein, the Is the vertical height of the current rocket, Is the vertical speed of the current rocket; 2) Resetting the intermediate variable: ; 3) Resetting the iteration count variable: ; 4) Resetting the flag bit: ; 5) Initializing thrust Based on the current And rated thrust of engine Initializing three vertical thrusts: ; Wherein, the Thrust for 100% working condition of the engine; (2) Iterative operation This section is used to solve the simplified kinetic equation to obtain Further calculate : 1) Updating the iteration count: 2) Calculating a function value The function represents the current thrust And estimating the working time The error of the rocket speed relative to the regulation target of reducing the vertical speed to zero is 0, the speed of the rocket during landing is just zero, if the rocket speed is greater than 0, the speed is greater than zero during landing, and if the rocket speed is less than 0, the speed is zero when landing is not equal; Wherein the method comprises the steps of Gravitational acceleration; In order to estimate the mass of the rocket, Marking a specific impulse value for the engine; 3) Calculating the derivative of a function : ; 4) Updating Updating using Newton's iterative formula ; 5) Clipping: ; 6) Updating the flag bit Judging whether the convergence condition is satisfied or the maximum iteration number is reached If it is Stopping the iteration; 7) Return and continue iteration if Returning to the starting point of the iterative operation, and continuing the iterative operation; When (when) Indicating the end of iteration, calculating the throttle ratio increment index : 。
5. The method according to claim 3 or 4, wherein the calculation method of step S3 comprises: Determining an optimal virtual throttle ratio in the iterative process through step S2 Then, the three-dimensional thrust control command is converted into an actual three-dimensional thrust control command: s31, calculating vertical virtual thrust of three computer sections : S32, calculating the horizontal virtual thrust component of the three computer segments And : According to the current attitude angle of the rocket, the total thrust vector is calculated from the vertical thrust component so as to ensure that the total thrust vector points to the landing target direction: In the formula, Is used as a pitch angle of the light beam, Is a yaw angle; s33, calculating total thrust of three computer sections : S34, calculating and limiting the actual throttle ratio of the three machine sections : To calculate the total thrust To a corresponding throttle ratio and ensures that it is within the physical operating limits of the engine to form the final thrust command: Wherein, the And The maximum and minimum throttle ratios allowed by the engine, respectively.
6. The method according to any one of claims 1-5, further comprising the step of calculating a thrust vector of a section and limiting a throttle ratio after the three rocket machines are turned into one rocket machine, wherein the step realizes fuel optimization by solving the thrust of the section and the working time of the section on line.
7. The method of claim 6, wherein the one-segment thrust vector calculation and throttle ratio clipping calculation method comprises: (1) Adopting polynomial guidance to obtain the optimal meeting the terminal speed and position constraint And , Is the thrust of one machine section, The working time is one working time; (2) Calculating a horizontal virtual thrust component of a computer segment And : The same as the three-machine section, the vertical thrust component is converted into a three-dimensional thrust vector according to the attitude angle of the rocket In the formula, Is used as a pitch angle of the light beam, Is a yaw angle; (3) Calculating total thrust of a computer section : (4) Calculating and limiting an actual throttle ratio of a machine section : Wherein, the Is the thrust of 100% working condition of a single engine.
8. A reusable rocket landing stage fuel optimal thrust adjustment device employing the method of claim 6 or 7, comprising: The thrust virtual throttle ratio dynamic adjusting module is used for continuously and iteratively calculating and adjusting the thrust virtual throttle ratio of the engine, and searching the minimum three-engine thrust meeting the landing requirement so as to realize the optimal fuel; And the thrust vector space synthesis module is used for converting the vertical thrust component into a thrust vector in the three-dimensional space based on the optimized virtual throttling ratio obtained by iteration and in combination with the current attitude angle of the rocket.
9. The apparatus as recited in claim 8, further comprising: and the one-section thrust vector calculation and throttle ratio amplitude limiting module is used for solving the one-section thrust and the one-machine working time on line after the three rocket machines are converted into one machine, so as to realize the fuel optimization.
10. A storage medium having stored thereon an executable program that, when invoked, performs the method of optimal thrust adjustment of a fuel for a reusable rocket landing stage of any one of claims 1-7.

Description

Reusable rocket landing zone fuel optimal thrust adjusting method, device and storage medium Technical Field The invention relates to the technical field of reusable rocket navigation, guidance and control (GNC), in particular to a reusable rocket landing zone fuel optimal thrust adjusting method, a reusable rocket landing zone fuel optimal thrust adjusting device and a storage medium. Background In the key stage of vertical landing of a reusable rocket, high-precision adjustment of engine thrust is a core technical challenge for ensuring landing safety and precision and realizing efficient utilization of fuel. For a nine-engine configuration liquid oxygen methane reusable rocket, the thrust adjustment mechanism is particularly complex. In the initial stages of landing, the rocket must start multiple engines (typically three) to work in concert, since the thrust of a single liquid oxymethane engine is typically insufficient to provide sufficient thrust reversibility. However, if three engines are relied upon for deceleration throughout the process, there is a significant problem in that the minimum thrust of the three engines tends to be greater than the weight of the rocket at the landing tip (the lighter mass after fuel consumption). Under the condition of overlarge thrust margin, if guidance control errors or external disturbance exist, the phenomenon of reverse vertical speed direction is very easy to occur when the rocket is at a higher position from the ground. This phenomenon not only severely interferes with the stability of the landing control, possibly leading to trajectory divergence, but also consumes additional fuel. In contrast, at the end of the landing leg, the rocket's gravity is typically between the maximum thrust and the minimum thrust of a single engine. At this time, if the operation mode can be switched to the single engine operation mode accurately, and fine thrust adjustment is performed, the rocket can be made to achieve an approximate suspension state (i.e., the engine thrust can be approximately balanced with the rocket gravity, and smooth and controlled descent is achieved). This stand-alone mode of operation is effective in avoiding vertical speed reversals while extending the time of flight (or "hover time") of the landing tip. The longer hover time provides a sufficient time window for horizontal attitude adjustment and landing correction of the rocket, thereby being capable of meeting the stringent landing accuracy requirements. Currently, no fuel-optimal thrust adjustment method for this particular engine configuration and operating mode switching is found in the prior art. Existing thrust regulation strategies exist mostly at the theoretical research level, for example, based on simple Proportional Integral Derivative (PID) control, or depending on preset thrust curves, lack on-line adaptation to real-time flight conditions (in particular mass, speed, altitude) and uncertainty, far from engineering practices. These theoretical foundation deficiencies and gaps from engineering practices can result in the potential for over-or under-regulation affecting landing safety or accuracy during actual landing. Therefore, there is a need for a method for efficiently, accurately, and online generating fuel-optimal thrust adjustment commands to address challenges in complex flight environments. Disclosure of Invention In the vertical landing process of the liquid oxygen methane reusable rocket aiming at nine engine configurations, the existing method lacks an effective fuel optimal thrust real-time adjustment strategy, so that fuel optimal cannot be realized when the engine working modes are switched, and the problems of reverse vertical speed, influence on landing safety and landing precision can occur. The invention provides a reusable rocket landing section fuel optimal thrust adjustment method, which adopts a mode of combining energy analysis and analysis iteration, and realizes fuel optimal thrust control in the rocket landing process by adjusting the engine thrust virtual throttle ratio on line in real time and combining thrust closed-loop control, thereby ensuring safe and accurate landing. The fuel optimal thrust adjusting method for the reusable rocket landing zone provided by the disclosure mainly comprises the following steps: S1, constructing a threshold value index based on energy analysis, namely taking an upper limit index of energy of one machine section as a criterion for adjusting thrust of three machine sections, namely, if the index is larger than a set threshold value, then, transferring the three machine sections to the machine section for safe landing, and searching the minimum three machine thrust meeting the landing requirement according to the criterion to realize fuel optimization; S2, dynamically adjusting the three-section thrust virtual throttle ratio, namely simplifying the motion of the three sections into vertical motion, taking the vertical throttle ra