Method of forming program for orientation of cryogenic stage at terminal control of injection into preset orbit

FIELD: terminal control of motion trajectory of cryogenic stages injecting spacecraft into preset orbits by means of cruise engines.

SUBSTANCE: swivel combustion chamber of cruise engine is used for angular orientation and stabilization of cryogenic stage of spacecraft. Proposed method includes predicting parameters of motion of cryogenic stage at moment of cut-off of cruise engine; deviation of radius and radial velocity from preset magnitudes are determined; angle of pitch and rate of pitch are corrected and program of orientation of thrust vector for subsequent interval of terminal control is determined. By projections of measured phantom accelerations, angle of actual orientation of cruise engine thrust vector and misalignment between actual and programmed thrust orientation angles are determined. This misalignment is subjected to non-linear filtration, non-linear conversion and integration. Program of orientation of cryogenic stage is determined as difference between programmed thrust orientation angle and signal received after integration. Proposed method provides for compensation for action of deviation of cruise engine thrust vector relative to longitudinal axis of cryogenic stage on motion trajectory.

EFFECT: enhanced accuracy of forming preset orbit.

5 dwg, 1 tbl

 

The present invention relates to the field associated with the pointing of the spacecraft into orbit, which provides adjusted the parameters of their movement at the end of the maneuver.

The closest technical solution is the method of forming the orientation programme upper stage (RB) in the longitudinal control when performing active maneuver [1], namely, that in the process of implementation of this maneuver periodically with tact terminal control Typredict the motion parameters of the booster unit at the time of main engine cutoff (MT), determined by him predictable variations in the radius, radial velocity from their values on a given orbit and amendments to the program parameters, orientation, pitch, ensure the implementation of terminal conditions, and form on the basis of the elaborated programme of orientation of the upper stage, pitch ϑCRat regular interval of terminal control in the form:

where ϑCRsoftware pitch angle as a booster;

ϑ0- the initial value of the software angle;

- the rate of change of the software angle;

t is the time measured from the moment the forecast.

For a start control parameter values ϑ0 ,are specified in the flight task.

The disadvantage of this method is the assumption that the thrust vectorthe main engine is directed along the longitudinal axis of the upper stage. Thrust vector deflectionthe main engine from the longitudinal axis at an angle Δϑperror results of the implementation of the specified motion trajectory.

When used in booster blocks engines for angular stabilization of creating with their help control moments about the center of mass is accomplished by deflection of the combustion chamber main engine relative to the longitudinal axis. The average (balancing) component of the deviation of the combustion chamber main engine, characterized by the angle Δϑdthat has the greatest effect on the accuracy of the implementation of the motion trajectory. The magnitude of the balancing deviations of the combustion chamber main engine depends on the displacement of the center of mass of the upper stage with respect to its longitudinal axis, deformation of the frame of the suspension main engine, installation errors axis of the combustion chamber and other reasons.

The technical result of the invention is to compensate the influence of the thrust vector deflection of main engine relative to the longitudinal axis on the accuracy of implementing the function specified motion trajectory and increase thereby the precision of formation of a given orbit.

This technical result is achieved by the fact that in the known method of forming the orientation programme as a booster in terminal management move it into orbit, namely, that when the current value of the software pitch and speed changes at each step of the terminal control predict the motion parameters of the booster unit at the time of cutoff of the main engine, determine the deviation of the radius and radial velocity from their values on a given orbit, form correction signals by the angle and angular velocity of the pitch, adjust the value of the pitch angle and angular velocity of, determine the orientation of the thrust vector for the next interval, terminal management, advanced determined by the projections of the measured apparent acceleration on the axis of the coordinate system adopted for the reference software of the pitch angle, the orientation of the thrust vector propulsion engine in this coordinate system and its deviation from the value of the software orientation angle of the thrust vector, perform nonlinear filtering of this deviation and the subsequent non-linear transformation of the filtered signal, integrate the converted signal, limit it to a given level and determine the orientation program as a booster by subtracting this limited si is Nala from the program orientation of the thrust vector of the cruise engine.

Thus, this technical result is achieved in that the upper stage rejects pitch at an additional angle Δϑdin the opposite direction of the thrust vector deflectionmain engine relative to the longitudinal axis, and to this end, the programme orientation of the upper stage, defined by the angleshould be specified in the form:

providing current to the thrust direction defined by the angle ϑCR,

where- corrected a software pitch angle as a booster;

ϑCRsoftware pitch angle as a booster;

Δϑd- the deflection angle of the propulsion engine.

Figure 1 shows the block diagram of the processing unit orientation programs as a booster according to the method, determining the desired direction of thrust vector propulsion engine; given in figure 2 block diagram of the circuit formation program orientation upper stage of the proposed method; figure 3 shows the orientation angles of the thrust vector ϑpsoftware orientation of the thrust vector ϑCRand the deviation of the direction of the thrust vector Δϑpfrom its programmatic orientation; figure 4 presents the structure of the nonlinear blocks is anoi orientation, nonlinear transformation and the formation of compensating amendments; figure 5 shows the change of orientation programs upper stage in the process of induction into orbit on known and proposed methods for different values of the angles of deflection of the thrust vector in the balance.

Block diagram of the processing unit program orientation upper stage that implements the method presented in figure 1, where 1 unit of the forecast variance (BPO) from a given orbit and calculation of sensitivity functions, 2 - block of corrections (BKP) software control, 3 - block correction (BC) parameters of the program orientation.

In block 1 (BPO) on known parameters of the orientation programme ϑ0andcontinuously determines the current value of ϑCR. At each i-th step of the terminal control for the predictable time off main engine calculates the deviation from the target orbit at the radius-vector ΔR, radial velocity ΔV and function of the sensitivity of the L, J, S, Q computed variance to modify the parameters of the program orientation - pitch and speed changes.

On the basis of these data in block 2 (BKP) are calculated corrective amendments Δϑ0i,the parameters of the program orientation, AV block 3 (Bq) are the adjusted parameters of the orientation programme for the next step of terminal control.

The block diagram of the circuit formation program orientation upper stage of the proposed method are presented in figure 2, where 4 - block the formation of orientation programs (FFT) according to the method, a 5 - unit of measurement of the apparent acceleration (BICU), 6 - shaping unit variance (BPC) of the thrust vector relative to the longitudinal axis, 7 - block nonlinear filtering (BPF), an 8 - block nonlinear transformation (BNP), 9 - shaping unit compensating amendments (BFCP), 10 - unit formation program orientation (BFPO) of the proposed method.

In unit 4 (FFT) by a known method formed the program of the orientation of the thrust vector ϑCRof the form (1).

From block 5 (BICU) are the values of the projections of the measured apparent acceleration booster,on the axis of the coordinate system OgXgYgused to reference software and the current pitch angles (figure 3).

In block 6 (BPC) is calculated misalignment between the direction of the thrust vector and program orientation ϑCRdetermined by the angle Δϑp. This is determined by the current orientation of the thrust vector angle ϑp:

Angle ϑpcan be represented as:

ϑpCR+Δϑp

and so

<> sinϑp=sinϑCR·cosΔϑp+cosϑCR·sinΔϑp.

Given the small values of the angle between the Δϑpits value is determined from the last equation by the formula:

the error signal passes through a chain of consecutive blocks 7, 8, 9, the structure of which is presented in figure 4. The transfer function of block 7 (BPF) has the form:

wherethe time constant of the filter;

Tof- gain linear plot characteristics.

The maximum rate of change of the output signal Δϑfunit 7 (BPF) is determined by the size restrictionsand Kf.

Block 7 (BPF) excludes the passage of high frequency signal components Δϑpto the input unit 8 (BNP).

Block 8 (BNP) is a nonlinear element, consisting of the restrictions of the output signal level, dead zone Δmnand having a gain Knon a linear plot characteristics. Signalthe output of block 8 (BNP) is formed on the dependencies:

In block 9 (BFCP) vypolnjaete the integration signal Δ ϑnand the limitation of the output signal Δϑdlevel ±Δϑd:

Program orientationformed in the block 10 (BFPO), to the first input of the unit 4 (FFT) signal program orientation of the thrust vector ϑCRand on the second signal Δϑdfrom block 9 (BFCP):

Angle Δϑdchanged up until the orientation of the thrust vector ϑpbecomes equal to the generated software corner orientation ϑCR. In this case, Δϑp=0 and the input unit 9 (BFCP) signal Δϑn=0, which indicates the achievement of an angle Δϑdthe value of balancing the deviation of the camera main engine.

To evaluate the effectiveness of the proposed method of forming the orientation programme of the Republic of Belarus with regard to the compensation of the deflection of the thrust vector propulsion engine of the comparative modeling of removing the upper stage on the target circular orbit with altitude Hkr=212244 m when using this method and prototype.

Values of peak heights Handand perigee Npat different angles balancing deviations of the combustion chamber Mar is avago engine δ MDrequired to parry relevant perturbing torques shown in the table for the two control methods. It also represents the deviation of the heights of climax ΔNandand perigee ΔNprelative to a given height Hkrcircular orbit.

OptionMethodδMD[deg]Hand[m]Hp[m]ΔNand[m]ΔNp[m]
1The placeholder0212651211837407-407
2The placeholder522269120176710449-10477
3Offer5212659211826415-418

As can be seen from the above results, the application of the proposed method in terms of deviations of the combustion chamber main engine 5 degrees provides compensation of the perturbation and allows you to achieve the accuracy of the parameters generated by the orbit, which gives way to the prototype provided that the direction of the thrust vector with the longitudinal axis of the spreader block.

In the simulation b the used parameter values in blocks of 4: Tof=0,15 1/s,Δmn=0.16 deg,Ton=0,15.

Figure 5 presents the processes of the formation programs of orientation in the process guidance into orbit and figures 1÷4 indicated the following options:

1, 2 - a software orientation angle ϑCRfor options 1 and 2 of the table

3 - software orientation anglefor option 3 of the table

4 - change the angle Δϑdoption 3.

The sources of information.

1. Assyro, Vinacoal, VIB, Ligalig "Algorithm targeting upper stage with unregulated main engines and small thavarungkul". Aerospace engineering and technology, No. 1, 1998

The method of forming the orientation programme as a booster in terminal management move it into orbit, namely, that when the current value of the software pitch and speed changes at each step of the terminal control predict the motion parameters of the booster unit at the time of cutoff of the main engine, determine the deviation of the radius and radial velocity from their values on a given orbit, form correction signals by the angle and angular velocity of the pitch, adjust the angle and angular velocity of the pitch, define the program orientation of the thrust vector for the next interval, terminal control, characterized in that determined by the projections of the measured apparent acceleration on the axis of the coordinate system adopted for the reference software of the pitch angle, the orientation of the thrust vector propulsion engine in this coordinate system and its deviation from the value of the software orientation angle of the thrust vector, perform nonlinear filtering of this deviation and the subsequent non-linear transformation of the filtered signal, integrate the converted signal, limit it to a given level and determine the orientation program as a booster by subtracting this limited signal from the orientation of the thrust vector of the cruise engine.



 

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