CN112329136A - Carrier rocket online flight program reconstruction method based on balanced flight theory - Google Patents
Carrier rocket online flight program reconstruction method based on balanced flight theory Download PDFInfo
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Abstract
The invention discloses a carrier rocket online flight program reconstruction method based on a balanced flight theory, which comprises the following steps of: firstly, calculating the initial instantaneous range angular velocity of the rocket and the flight angular velocity of a target circular orbit; secondly, dividing the initial instantaneous range angular velocity to the flight angular velocity of the target circular orbit as boundary points into a plurality of sampling points; secondly, calculating a thrust acceleration inclination angle and a time recurrence value corresponding to each sampling point, and calculating a range angle of each sampling point according to the instantaneous range angular velocity and the time recurrence value; and finally, acquiring the flight program angle of each sampling point to complete the reconstruction of the flight program. The method provides a quick algorithm for reconstructing an on-line flight program by combining a balanced flight theory (including modes of balanced flight, quasi-balanced flight and the like) against the background that a carrier rocket encounters a non-fatal thrust system fault in a flight section outside the atmosphere, has the advantages of small calculation amount and high generation speed, is suitable for a disposal program of a rocket-borne computer fault mode, and can effectively improve the autonomy and intelligence of the rocket.
Description
Technical Field
The invention relates to the technical field of aerospace, in particular to a carrier rocket online flight program reconstruction method based on a balanced flight theory.
Background
The normal flight procedure of the carrier rocket is strictly time-dependent, and the precise time sequence design is carried out according to the factors of the flight environment, rocket body structure, fuel consumption, power characteristics, effective load and the like of the rocket and by comprehensively considering the target orbit of the carrier mission, so that the time sequence of the action logic of each executing mechanism is controlled, and therefore, the flight procedure needs to be revised every time the launching mission is executed. Because of the need of satisfying many engineering constraints, this calculation process is very complicated, the calculated amount is very large, and the real-time requirement cannot be satisfied, and usually, the firing data is injected before the rocket is fired.
The rocket inevitably encounters various faults in the process of executing tasks, and the occurrence time and the fault mode are uncertain. When the rocket has sudden thrust failure, the rocket flies according to a preset program to cause task failure, for example, in the flight of a Long-March five-number remote second carrier rocket, the thrust of a core first-stage engine is instantaneously and greatly reduced, so that the rocket cannot reach the preset flying speed and height, and finally, a second-stage rocket and a satellite enter in the Western Pacific again to launch a task and lose profits. If the flight program can be adjusted timely, the loss of the mission can be avoided, for example, the Tuxing 5 carrier rocket carries the Apollo 13 airship, the second-stage main engine of the rocket shuts down 132 seconds in advance due to reasons, the other 4 engines work for 34 seconds in a compensatory way, and the airship smoothly enters the lunar orbit. At present, most of the existing rockets in China do not have the capabilities of real-time fault detection, fault-tolerant processing and redundancy reconstruction, and once major abnormalities such as power system faults occur in the flight process, the coping strategies cannot be executed autonomously, so that the development of the intelligent rocket technology is very urgent.
The traditional carrier rocket guidance method adopts a perturbation guidance or track tracking mode, namely a standard trajectory is designed offline in advance, when the carrier rocket actually flies, a guidance control system controls the actual flight trajectory of the carrier rocket to perturb near the standard trajectory, and the actual flight trajectory is attached to the standard trajectory as far as possible. However, the guidance method is low in fault tolerance, when the guidance method encounters a thrust abnormal fault, the performance of the carrier rocket is reduced, and sufficient power cannot be generated to continue tracking program ballistic flight, so that the actual flight trajectory greatly deviates from the standard ballistic trajectory, and even serious consequences such as rocket instability and the like may occur. At the moment, a new flight program needs to be generated on line, belongs to the problem of rapid track optimization, is essentially an optimal control problem, and is complicated in solving process due to state constraint and control constraint and high nonlinearity of a kinetic equation. Therefore, in order to improve the reliability and safety of the carrier rocket, the research on the flight procedure online generation technology is particularly important.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a carrier rocket online flight program reconstruction method based on a balanced flight theory,
a carrier rocket online flight program reconstruction method based on a balanced flight theory comprises the following steps:
step one, calculating the thrust acceleration a of the rocket in a thrust fault modecIf the rocket meets the balance flight condition or the quasi-balance flight condition and meets the rescue condition, entering a second step;
step two, calculating the initial instantaneous range angular velocity omega of the rocket and the flight angular velocity n of the target circular orbit; wherein:
beta represents the initial range angle, t represents time;
mu represents an earth gravity coefficient, and r represents a geocentric distance at the fault moment;
step three, dividing the initial instantaneous range angular velocity omega to the flight angular velocity N of the target circular orbit as boundary points, and dividing the boundary points into N +1 sampling points at equal intervals, namely omega0＝ω,ω1,ω2,…,ωk,…,ωNN, wherein: omegakThe instantaneous range angular velocity of the kth sampling point, k being 0,1 … N;
step four, calculating the thrust acceleration a of the kth sampling point rocketckJudging that the rocket meets a balanced flight condition or a quasi-balanced flight condition;
step five, obtaining the thrust acceleration inclination angle theta of the rocket at the kth sampling pointPkAnd a time recurrence Δ tkThe method specifically comprises the following steps:
for balanced flight: adopting an expression 24) to calculate the thrust acceleration inclination angle thetaPkExpression 25) is adopted to calculate the maneuvering orbital transfer time t from the elliptical trajectory to the circular orbit of the balanced flight at the kth sampling pointk：
Time recursion value Δ tk＝tk-1-tk，Δt0Is a given value;
aiming at quasi-balanced flight: adopting expression 26) to calculate the thrust acceleration inclination angle thetaPkAdopting expression 27) to calculate the transition time Delta T from quasi-equilibrium flight to equilibrium flight of the kth sampling pointk：
Wherein: v. ofθkThe circumferential velocity component corresponding to the angular velocity of the kth sampling point,
time recursion value Δ tk＝ΔTk-1-ΔTk，Δt0Is a given value;
step six, calculating the range angle beta of the kth sampling point by adopting an expression 28) according to the instantaneous range angular velocity and the time recurrence value of the kth sampling pointk：
Step seven), calculating the flight procedure angle of the kth sampling point according to the expression 29)
And step eight, taking k as k +1, if k is less than or equal to N, returning to the step four, otherwise, completing the reconstruction of the flight program.
Preferably, the rocket is judged to meet the balance flight condition or the quasi-balance flight condition as the thrust acceleration a to the rocketcAnd judging, specifically:
if the thrust acceleration a of the rocketcExpression 12 is satisfied), the rocket enters a balanced flight state:
wherein: g0Is the acceleration of the gravity of the circular orbit,
if the thrust acceleration a of the rocketcSatisfying expression 15) but not expression 12), the rocket enters a quasi-equilibrium flight state:
wherein: Δ h is the height margin; v. ofθIs the circumferential velocity component at the moment of failure,
if the thrust acceleration a of the rocketcExpression 15 is not satisfied), the rocket enters the atmosphere to crash.
Preferably, in the above technical solution, the step of judging whether the rescue condition is satisfied specifically includes:
step a1, estimating the speed impulse delta v of the current rocket actual fuel level through an expression 23); estimating the total velocity increment delta v required by rocket in-orbit through an expression 24)Re：
Δv＝vidk-Δv1k-Δv2k-Δv3k 23)；
Wherein: v. ofidkThe speed generated by the thrust of the rocket under the action of vacuum gravity-free force is called as ideal speed; Δ v1kThe velocity loss caused by the gravitational acceleration component, called gravitational loss; Δ v2kLoss of speed due to drag; Δ v3kThe speed loss caused by the atmospheric static pressure when the engine is operating in the atmosphere;
balancing rocket thrust during flightAcceleration of force acAverage value of (d);
for balancing the thrust acceleration a of the rocket during flightcAverage value of (d);
step a2, speed impulse Deltav of current rocket actual fuel level and total speed increment Deltav required by rocket in-orbitReAnd (3) comparison:
if the current actual fuel level of the rocket has a velocity impulse delta v which is more than or equal to the total velocity increment delta v required by the rocket in-orbitReJudging to be rescued;
if the current actual fuel level of the rocket has a velocity impulse delta v smaller than the total velocity increment delta v required by the rocket to enter the orbitReIf the thrust loss is too large, the rescue cannot be carried out, and the rescue is abandoned.
The invention provides a carrier rocket online flight program reconstruction method based on a balanced flight theory, which comprises the following steps of: firstly, calculating the initial instantaneous range angular velocity of the rocket and the flight angular velocity of a target circular orbit; secondly, dividing the initial instantaneous range angular velocity to the flight angular velocity of the target circular orbit as boundary points into a plurality of sampling points; secondly, calculating a thrust acceleration inclination angle and a time recurrence value corresponding to each sampling point, and calculating a range angle of each sampling point according to the instantaneous range angular velocity and the time recurrence value; and finally, acquiring the flight program angle of each sampling point to complete the reconstruction of the flight program. The method provides a quick algorithm for reconstructing an on-line flight program by combining a balanced flight theory (including modes of balanced flight, quasi-balanced flight and the like) against the background that a carrier rocket encounters a non-fatal thrust system fault in a flight section outside the atmosphere, has the advantages of small calculation amount and high generation speed, is suitable for a disposal program of a rocket-borne computer fault mode, and can effectively improve the autonomy and intelligence of the rocket.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of a reconstruction method of an online flight procedure of a carrier rocket in the embodiment;
FIG. 2 is a schematic view of a transient ellipse in ballistic flight;
FIG. 3 is a schematic diagram of the mechanical analysis of a rocket in flight outside the atmosphere according to the present invention;
FIG. 4 is a schematic view of a force analysis of a continuous thrust rocket according to the present invention;
FIG. 5(a) is a schematic diagram of guidance law (thrust acceleration inclination) for balanced flight;
FIG. 5(b) is a schematic diagram of guidance law (thrust acceleration inclination angle) of quasi-equilibrium flight;
FIG. 6 is a schematic view of thrust acceleration inclination and angular deviation of a rocket in accordance with the present invention;
FIG. 7 is a graph of range angle, local velocity angle, and flight procedure angle during flight after a fault in accordance with the present invention;
FIG. 8 is a time-varying plot of rocket airspeed and altitude after reconstruction of the inventive flight procedure.
Detailed Description
Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways, which are defined and covered by the claims.
Example (b):
a carrier rocket online flight program reconstruction method based on a balanced flight theory is disclosed, and the specific process is detailed in figure 1, and the method specifically comprises the following steps:
determining whether the flight state is a quasi-balance flight state or a balance flight state, and then performing corresponding reconstruction according to the specific flight state:
aiming at quasi-balanced flight: firstly, angular velocity sampling is carried out, then transition time is calculated, then thrust acceleration inclination angle is calculated, and finally program angle is calculated, if flight program reconstruction is completed, flight is carried out according to a reconstruction program, otherwise, the steps are continuously circulated to carry out flight program reconstruction.
Aiming at quasi-balanced flight: firstly, carrying out angular velocity sampling, then calculating the maneuvering orbital transfer time, then calculating the thrust acceleration inclination angle, and finally calculating a program angle, if the reconstruction of the flight program is completed, flying according to the reconstruction program, otherwise, continuing to circulate the steps to reconstruct the flight program.
The orbit entering capability of the rocket is evaluated, and the details are as follows:
according to the theory of rocket ballistics, the rocket trajectory is a portion of an elliptical orbit of the geocenter, as shown in FIG. 2. Due to different mission missions, the trajectories of a carrier rocket and a ballistic missile are also different, the instantaneous elliptical orbit near point of the carrier rocket orbit point is generally above the safe height, and the elliptical orbit near points of the last-stage main engine shutdown point of the ballistic missile intersect with the earth.
In the air layer flight section before the orbit, the rocket motion is generally expressed as the lifting process of the flight height and the speed, but in consideration of the engineering constraints such as the actual thrust-weight ratio of the rocket and the like, the two lifting processes do not require synchronization but are emphasized to achieve better efficiency. For example, in the section before the point of entry, a strategy of continuously increasing the speed and making the altitude change more stable is often adopted (i.e., the speed increment is mainly reflected in the circumferential direction, and the radial speed is basically kept constant), and at this time, the motion of the rocket is in the stage of the far point of the instantaneous elliptical orbit and continuously increasing the near point, such as near point lifting in fig. 2. If the rocket has insufficient thrust, the height of the trajectory near the place cannot be timely lifted, the intersection of the trajectory and the earth cannot be avoided, and according to the elliptic trajectory theory, the height of the trajectory in subsequent rocket flight continuously drops, and finally the task fails.
The rocket motion under the thrust failure mode is subjected to mechanical analysis, a local horizontal coordinate system is established (the original point is the rocket center of mass, and the three axes are respectively along the radial direction, the circumferential direction and the ballistic surface normal direction), the rocket stress is concentrated in the ballistic plane outside the atmosphere, and the stress conditions of the rocket body in the radial direction and the circumferential direction are shown in fig. 3, wherein: the radial force is the radial component of the gravity, the centrifugal force and the thrust, and the resultant force determines the motion of the rocket in the radial direction, namely the height direction, wherein the centrifugal force is related to the circumferential speed and the orbit height. The circumferential force is the circumferential component of the thrust, the effect is to change the circumferential velocity, and at the same time, the circumferential velocity change will directly affect the centrifugal force.
If the thrust value is large enough, the rapid acceleration in the circumferential direction can be realized on the basis of ensuring the radial three-force balance, and the rocket has higher maneuvering orbital transfer efficiency; if the thrust is too small, the radial three-force balance cannot be supported, and at the moment, if the speed cannot be effectively increased in the living height range, the centrifugal force is improved, and finally the rocket can be crashed.
The magnitude of the engine thrust for the radial balance portion is a major loss of capacity because it is not translated into a speed increment (understandable against impulse effects); therefore, the more the thrust is reduced when the rocket fails, the longer the flight time is, and the larger the ratio of the capacity loss is; it can be extended from this that if the radial component of the thrust is used to ensure the radial force balance, the circumferential component of the thrust is accelerated, and the thrust direction is adjusted in real time as the circumferential velocity increases and the centrifugal acceleration increases, so that the radial force is always balanced, the minimum capacity loss is realized at the acceleration level, and the optimal ballistic adjustment is also realized. The flight dynamics mechanism analysis not only can explain the basic principle that thrust fault mission loss occurs in the air layer flight section of the rocket before the rocket enters the orbit, but also provides an idea for fault disposal strategy research.
In the process that the rocket flies out of the atmospheric layer and runs towards the target orbit, a rocket stress model of continuous thrust is shown in fig. 4, the rocket is under the action of the gravity of the earth and the thrust of an engine, and the action of centrifugal inertia force needs to be considered in a local horizontal coordinate system. In FIG. 4, OEDenotes the geocentric, beta denotes the range angle, r denotes the geocentric distance, acIndicating thrust acceleration (vector), arRepresenting the radial component of thrust acceleration, aθRepresenting the circumferential component of thrust acceleration, ΘPIndicating thrust acceleration inclination (i.e. thrust acceleration a)cAngle to the local horizontal, also called best guidance law), v represents the velocity vector.
The mass change in rocket flight is attributed to the change of acceleration, and the rocket flight dynamics are obtained in the radial direction and the circumferential direction of a local horizontal coordinate system as shown in an expression 1):
wherein: t represents time, and μ represents an earth gravity coefficient.
Thrust acceleration a of rocketcThe determination is determined according to the thrust fault mode, can be a determined time function, and can also be measured in real time. This thrust acceleration is also determined over time, which is generally determined by default as a failure mode, and is not a constant, but rather a time-varying quantity, without measurement.
When the balance flight is satisfied, the radial total acceleration component and the velocity component in the flight process are both 0, namely
Considering the determination of the magnitude of the continuous thrust acceleration, the direction is adjustable, and the thrust acceleration is decomposed and substituted into an expression 1) to obtain an expression 2):
obtaining an expression 3) from the expression 2), namely obtaining a thrust acceleration inclination angle (optimal guidance law) theta of balanced flightP：
The flight angular velocity of the target circular orbit
And range angular velocity
Substituting expression 3), and combining the two equations (specifically, squaring the left and right sides of the two equations in expression 2), and then adding the left and right sides) to obtain expression 4):
solving an ordinary differential equation based on expression 4) to obtain expression 5):
further integrating the two sides of the expression 5) to obtain an expression 6) for calculating the maneuvering orbital transfer time T from the elliptical trajectory to the circular orbit of the balanced flight:
by solving the quantitative integral expression 6), the maneuvering orbital transfer time from the elliptical trajectory to the circular orbit meeting the balanced flight condition can be obtained, and the flight process from the acceleration of the elliptical trajectory to the target circular orbit can be analyzed.
Such as: the ratio of the thrust acceleration to the gravitational acceleration of the circular orbit is set as
When ω < n, transforming denominator of integral term in expression 6) to obtain expression 7):
transforming expression 7) to obtain expression 8):
wherein:
the ratio of the range angular velocity omega to the flight angular velocity n of the target circular orbit; y is the ratio of the gravitational acceleration and the thrust acceleration of the circular orbit,
taking integral intermediate transformation variables tau and alpha, order
α＝τ2，τ0Is taken as the value of t at the moment t. Integrating expression 8) to obtain expression 9):
wherein: t is time; EllipticF is a first type of incomplete elliptic integral, or can be further expanded into expression 10):
the solution of the first type of incomplete elliptic integral can refer to the prior art, can provide a high-order approximate solution to meet the requirement of quick calculation, or can carry out calculation by using a numerical integration method. In the case of the expression 10) can be solved analytically, ω (T) (i.e. the range angular velocity at time T) is obtained actually, and T ∈ [0, T ∈ [ T ] []As a function of, and thus the thrust acceleration tilt angle thetaP(optimal guidance law) according to expression 3) can be solved quickly. Therefore, the balance flight process can be theoretically analyzed, the time and the fuel consumption of the whole process can be rapidly calculated, and the speed loss or the thrust efficiency of the continuous thrust orbital transfer process can also be calculated.
It should be noted that: the balanced flight state only represents temporary safety and does not represent long-term danger relief, if a fuel leakage condition exists, the circumferential acceleration time is not long enough, the circumferential speed constraint required by a circular orbit can not be reached when fuel is exhausted, and the rocket still has difficulty in entering the safe orbit.
In the solving process of expression 10), the condition to be satisfied is expression 11):
when the rocket is in an acceleration section, and omega is less than or equal to n, the condition required to be met by balanced flight can be obtained as expression 12):
according to the balanced flight condition, whether the rocket is in a dangerous state or not or whether the rocket has self-rescue capability or not can be judged based on the thrust acceleration level of the rocket after the fault.
Due to the existence of the thrust acceleration circumferential component, the circumferential velocity component is increased, so that the centrifugal acceleration is increased continuously, the thrust acceleration component required for achieving radial force balance is reduced continuously, the circumferential direction and the radial direction are dynamic processes of mutual coupling and mutual conversion, and therefore, a certain margin also exists in the balanced flight conditional expression 12).
If it is not
The centrifugal acceleration can be increased according to the height level of the rocket, namely whether the rocket can be accelerated rapidly along the circumferential direction within the range of slightly reducing the allowable height, so that the further descending of the rocket is restrained, and the judgment can be carried out through time estimation.
The thrust acceleration is completely concentrated in the circumferential direction, and the radial negative acceleration, namely theta, is not consideredPWhen the thrust acceleration is 0, the effect of the thrust acceleration on the circumferential acceleration is the best, so the radial centrifugal acceleration is accelerated the fastest, the centrifugal acceleration and the gravitational force are balanced after the transition time delta T, and the rocket reachesThe survival height is given by r as the geocentric vectorL，rLR- Δ h, Δ h is a height margin, and can be approximated using expression 13):
wherein: v. ofθIs the circumferential velocity component at the moment of failure,
then the condition for achieving rocket landing to rise is expression 14):
i.e. the sum of centrifugal acceleration and thrust acceleration is greater than gravitational acceleration, avθFor the circumferential velocity increase in this process, Δ vθ≈acΔT。
If the thrust acceleration a of the rocketcExpression 15 is not satisfied), the rocket enters the atmosphere to crash.
If the thrust acceleration a of the rocketcSatisfying expression 15) but not satisfying expression 12), the rocket enters a quasi-equilibrium flight state.
In fact, during the flight, the acceleration in the circumferential direction will make the speed increase fastest, the centrifugal acceleration increase fastest, but the initial radial negative acceleration value in this case is also the largest, and is also fast under the altitude; conversely, if the entire thrust is applied in the radial direction, the negative acceleration in the radial direction is minimal, the height decrease is slow, but the centrifugal acceleration cannot be increased. Between the two extremes mentioned there is a compromise between a limited range of altitude reduction and a fast implementation of the equilibrium flight regime, which requires optimization of the thrust acceleration tilt angle and minimum burn-up if the transition time from quasi-equilibrium flight to equilibrium flight is minimized.
Expressing the centrifugal acceleration by the circumferential velocity component, expression 1) is transformed into expression 16):
after the time of delta T, the rocket can reach new balance to make r0Representing the initial ground center distance of quasi-equilibrium flight, and the ground center distance (r, also referred to herein as equilibrium flight initial ground center distance) is not changed, then r ═ r0Expression 17 is derived from expression 16):
for expression 17), the second order small quantity a is omittedc 2cos2ΘP·ΔT2Obtaining a transition time Δ T expression 18 from quasi-equilibrium flight to equilibrium flight):
the shortest transition time Delta T from quasi-equilibrium flight to equilibrium flight is
Yielding expression 19):
combining with expression 20), expression 21) can be adopted to calculate and obtain the thrust acceleration inclination angle (optimal guidance law) theta of quasi-equilibrium flightP：
By comparing expression 3) with expression 21), it can be found that satisfaction is satisfied
Balanced flight conditions of the condition, and satisfaction
The guidance law in the case of the quasi-equilibrium flight state of the condition is shown in fig. 5(a) and 5 (b). Under the quasi-equilibrium flight condition, the optimal direction of the thrust acceleration is not along the radial direction or the circumferential direction, but the different actions of the two directions are still considered, so that the shortest flight time of the radial force equilibrium can be realized. Since the balanced flight mode represents the most effective utilization mode of the thrust, the expressions 3) and 21) are also the optimal guidance schemes for the extraatmospheric flight section before the rocket enters the orbit.
Judging whether the rocket can be saved:
by expression 22) estimates the velocity impulse Δ v that the current rocket actual fuel level has:
Δv＝vidk-Δv1k-Δv2k-Δv3k 22)；
wherein: v. ofidkThe speed generated by the thrust of the rocket under the action of vacuum gravity-free force is called as ideal speed; Δ v1kThe velocity loss caused by the gravitational acceleration component, called gravitational loss; Δ v2kLoss of speed due to drag; Δ v3kThe speed loss caused by the atmospheric static pressure when the engine is operating in the atmosphere;
estimating total velocity increment delta v required by rocket in-orbit through expression 23)Re：
Wherein:
quasi-balance of thrust acceleration a of rocket in flightcAverage value of (d);
for balancing the thrust acceleration a of the rocket during flightcAverage value of (d); Δ T is the transition time from the quasi-equilibrium flight condition to the equilibrium flight condition; t is the maneuver orbital transfer time from the elliptical trajectory to the circular orbit of the equilibrium flight.
And
the average value can be obtained by averaging after integration, or other averaging methods can be used, and the average value is determined according to actual requirements.
The velocity impulse Deltav of the current rocket actual fuel level and the total velocity increment Deltav required by rocket to enter into orbitReAnd (3) comparison: if the current actual fuel level of the rocket has a velocity impulse delta v smaller than the total velocity increment delta v required by the rocket to enter the orbitReJudging that the thrust loss is too large to save, and giving up rescue; if the current actual fuel level of the rocket has a velocity impulse delta v which is more than or equal to the total velocity increment delta v required by the rocket in-orbitReThen the judgment can be saved.
The method can be used for reconstructing the flight program of the carrier rocket on line under the condition of saving, and specifically comprises the following steps:
firstly, calculating an initial instantaneous range angular velocity omega of the rocket and a flight angular velocity n of a target circular orbit;
secondly, dividing the initial instantaneous range angular velocity omega to the flight angular velocity N of the target circular orbit as boundary points, and dividing the boundary points into N +1 sampling points with equal intervals, namely omega0＝ω,ω1,ω2,…,ωk,…,ωNN, wherein:ωkthe instantaneous range angular velocity of the kth sampling point, k being 0,1 … N;
thirdly, calculating the thrust acceleration a of the kth sampling point rocketckJudging that the rocket meets a balanced flight condition or a quasi-balanced flight condition;
fourthly, obtaining a thrust acceleration inclination angle theta of the rocket at the kth sampling pointPkAnd a time recurrence Δ tkThe method specifically comprises the following steps:
for balanced flight: adopting an expression 24) to calculate the thrust acceleration inclination angle thetaPkExpression 25) is adopted to calculate the maneuvering orbital transfer time t from the elliptical trajectory to the circular orbit of the balanced flight at the kth sampling pointk：
Time recursion value Δ tk＝tk-1-tk，Δt0Is a given value;
aiming at quasi-balanced flight: adopting expression 26) to calculate the thrust acceleration inclination angle thetaPkAdopting expression 27) to calculate the transition time Delta T from quasi-equilibrium flight to equilibrium flight of the kth sampling pointk：
Wherein: v. ofθkThe circumferential velocity component corresponding to the angular velocity of the kth sampling point,
time recursion value Δ tk＝ΔTk-1-ΔTk，Δt0Is a given value;
fifthly, calculating the range angle beta of the kth sampling point by adopting an expression 28) according to the instantaneous range angular velocity and the time recurrence value of the kth sampling pointk：
Sixth step, calculating flight procedure angle of kth sampling point according to expression 29)
And seventhly, taking k equal to k +1, returning to the third step if k is less than or equal to N, and otherwise, completing the reconstruction of the flight program.
The specific application of this example is as follows:
simulation analysis is carried out on a power flight section outside an atmosphere of a certain type of two-stage carrier rocket, the failure mode is a non-fuel leakage engine thrust reduction failure, the failure time is set to be 400s, and the residual thrust proportion of the engine is 55%. The online reconstruction flight program adopts the rapid recursion calculation method; for the space flight segment before the orbit entering, a guidance law reconstruction flight program provides a thrust acceleration inclination angle required by guidance by adopting balanced flight or quasi-balanced flight, a ballistic differential equation is solved, and the flight program is reconstructed by utilizing an analytical theory of balanced flight according to the principle and the steps of flight program reconstruction. Since the range angle information is mainly from the rocket's own navigation system and is determined, the key part of the main classification flight procedure still represents the dip angle of thrust acceleration. The calculated thrust acceleration inclination angle and the angle deviation are shown in fig. 4, the angle deviation in the diagram is an online reconstruction algorithm and a four-order fixed-step-length guidance law reconstruction algorithm, relative to a five-order variable-step-length guidance law reconstruction algorithm, the maximum deviation of the obtained thrust acceleration inclination angle difference in the whole power flight segment is not more than 0.5 degrees, but due to the fact that an approximate analysis algorithm exists in the calculation process, the total calculated amount is small, the online reconstruction algorithm is high in precision and small in calculated amount, and the method is suitable for on-line calculation on an arrow.
In the simulation process, the idea of entering a circular orbit with safe altitude in the first step and then entering a large elliptical orbit in the far place is improved in the second step, wherein the balance flight theory is mainly considered in the previous step to reconstruct a flight program. Substituting the thrust acceleration inclination angle obtained by the online reconstruction strategy into a full rocket dynamics model to perform trajectory simulation, wherein in the flying process after the fault, the time-varying curve of the trajectory parameter angle is shown in fig. 5, and as can be known from fig. 5: the reconstructed flight procedure angle is mainly embodied as a flight time period of 400-800s, and research shows that the maximum value of the angular speed of the flight procedure angle between the first stage and the second stage is less than 0.5 degree/s, so that the design constraint of the flight procedure is met.
The time-dependent curves of flight speed and flight altitude are shown in fig. 6, it can be seen that there is a coordinated climbing process for flight speed and altitude, and there are two-stage speed-up processes in the 400-800s flight time period, and there is a difference in the speed rising slope due to the inconsistent magnitude of thrust acceleration. In the process, due to the existence of a relatively small radial velocity, the track height is improved within 400s, about 20-30km, and the ground center distance is small, so that the whole flight process is close to balanced flight. After entering the near-circular orbit, the engine is shut down, the speed is not increased any more, after flying for a period of time, the engine is started up again, the far place of the trajectory is lifted until the fuel is exhausted, and finally the near place height of the orbit entering point is 268km and the far place height is 33550km, so that the rocket is successfully saved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. A carrier rocket online flight program reconstruction method based on a balanced flight theory is characterized by comprising the following steps:
step one, calculating the thrust acceleration a of the rocket in a thrust fault modecIf the rocket meets the balance flight condition or the quasi-balance flight condition and meets the rescue condition, entering a second step;
step two, calculating the initial instantaneous range angular velocity omega of the rocket and the flight angular velocity n of the target circular orbit; wherein:
beta represents the initial range angle, t represents time;
mu represents an earth gravity coefficient, and r represents a geocentric distance at the fault moment;
step three, dividing the initial instantaneous range angular velocity omega to the flight angular velocity N of the target circular orbit as boundary points, and dividing the boundary points into N +1 sampling points at equal intervals, namely omega0＝ω,ω1,ω2,…,ωk,…,ωNN, wherein: omegakThe instantaneous range angular velocity of the kth sampling point, k being 0,1 … N;
step four, calculating the thrust acceleration a of the kth sampling point rocketckJudging that the rocket meets a balanced flight condition or a quasi-balanced flight condition;
step five, obtaining the thrust acceleration inclination angle theta of the rocket at the kth sampling pointPkAnd a time recurrence Δ tkThe method specifically comprises the following steps:
for balanced flight: adopting an expression 24) to calculate the thrust acceleration inclination angle thetaPkExpression 25) is adopted to calculate the maneuvering orbital transfer time t from the elliptical trajectory to the circular orbit of the balanced flight at the kth sampling pointk：
Time recursion value Δ tk＝tk-1-tk，Δt0Is a given value;
aiming at quasi-balanced flight: adopting expression 26) to calculate the thrust acceleration inclination angle thetaPkAdopting expression 27) to calculate the transition time Delta T from quasi-equilibrium flight to equilibrium flight of the kth sampling pointk：
Wherein: v. ofθkThe circumferential velocity component corresponding to the angular velocity of the kth sampling point,
time recursion value Δ tk＝ΔTk-1-ΔTk，Δt0Is a given value;
step six, calculating the range angle beta of the kth sampling point by adopting an expression 28) according to the instantaneous range angular velocity and the time recurrence value of the kth sampling pointk：
Step seven), calculating the flight procedure angle of the kth sampling point according to the expression 29)
And step eight, taking k as k +1, if k is less than or equal to N, returning to the step four, otherwise, completing the reconstruction of the flight program.
2. The method for reconstructing the online flight procedure of a launch vehicle based on the balanced flight theory as claimed in claim 1, wherein the condition that the rocket satisfies the balanced flight condition or the quasi-balanced flight condition is determined as the thrust acceleration a to the rocketcAnd judging, specifically:
if the thrust acceleration a of the rocketcExpression 12 is satisfied), the rocket enters a balanced flight state:
wherein: g0Is the acceleration of the gravity of the circular orbit,
if the thrust acceleration a of the rocketcSatisfying expression 15) but not expression 12), the rocket enters a quasi-equilibrium flight state:
wherein: Δ h is the height margin; v. ofθIs the circumferential velocity component at the moment of failure,
if the thrust acceleration a of the rocketcExpression 15 is not satisfied), the rocket enters the atmosphereAnd (4) crashing.
3. The method for reconstructing the online flight procedure of a launch vehicle based on the balanced flight theory as claimed in claim 2, wherein the step one of judging whether the rescue condition is satisfied specifically comprises the steps of:
step a1, estimating the speed impulse delta v of the current rocket actual fuel level through an expression 23); estimating the total velocity increment delta v required by rocket in-orbit through an expression 24)Re：
Δv＝vidk-Δv1k-Δv2k-Δv3k 23)；
Wherein: v. ofidkThe speed generated by the thrust of the rocket under the action of vacuum gravity-free force is called as ideal speed; Δ v1kThe velocity loss caused by the gravitational acceleration component, called gravitational loss; Δ v2kLoss of speed due to drag; Δ v3kThe speed loss caused by the atmospheric static pressure when the engine is operating in the atmosphere;
quasi-balance of thrust acceleration a of rocket in flightcAverage value of (d);
for balancing the thrust acceleration a of the rocket during flightcAverage value of (d);
step a2, speed impulse Deltav of current rocket actual fuel level and total speed increment Deltav required by rocket in-orbitReAnd (3) comparison:
if the current actual fuel level of the rocket has a velocity impulse delta v which is more than or equal to the total velocity increment delta v required by the rocket in-orbitReJudging to be rescued;
if the current actual fuel level of the rocket has a velocity impulse deltav is less than the total velocity increment delta v required by rocket in orbitReIf the thrust loss is too large, the rescue cannot be carried out, and the rescue is abandoned.
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| CN202111241049.2A CN113836645B (en) | 2020-10-27 | 2021-10-25 | On-line flight program reconstruction and orbit height maintenance control method for carrier rocket |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113836645A (en) * | 2020-10-27 | 2021-12-24 | 深圳三零三防务科技有限公司 | Method for reconstructing online flight program of carrier rocket and keeping and controlling track height |
| CN114018103A (en) * | 2021-11-08 | 2022-02-08 | 航天科工火箭技术有限公司 | Carrier rocket trajectory reconstruction method and system based on low thrust |
| CN114034215A (en) * | 2021-11-23 | 2022-02-11 | 航天科工火箭技术有限公司 | Rocket guiding method and device |
| CN114413691A (en) * | 2021-12-24 | 2022-04-29 | 北京航天自动控制研究所 | Cross-gliding-section analytic guidance reconstruction method for thrust descent fault of carrier rocket |
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2020
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113836645A (en) * | 2020-10-27 | 2021-12-24 | 深圳三零三防务科技有限公司 | Method for reconstructing online flight program of carrier rocket and keeping and controlling track height |
| CN113836645B (en) * | 2020-10-27 | 2024-02-02 | 深圳三零三防务科技有限公司 | On-line flight program reconstruction and orbit height maintenance control method for carrier rocket |
| CN114018103A (en) * | 2021-11-08 | 2022-02-08 | 航天科工火箭技术有限公司 | Carrier rocket trajectory reconstruction method and system based on low thrust |
| CN114034215A (en) * | 2021-11-23 | 2022-02-11 | 航天科工火箭技术有限公司 | Rocket guiding method and device |
| CN114034215B (en) * | 2021-11-23 | 2023-02-28 | 航天科工火箭技术有限公司 | Rocket guiding method and device |
| CN114413691A (en) * | 2021-12-24 | 2022-04-29 | 北京航天自动控制研究所 | Cross-gliding-section analytic guidance reconstruction method for thrust descent fault of carrier rocket |
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