CN104914873A - Coupling method for attitude and orbit control engine - Google Patents

Abstract

The invention provides a coupling method for an attitude and orbit control engine. An engine use method capable of considering two-degree-of-freedom sub-problems of orbit and attitude control is designed on the basis that six-degree-of-freedom control instruction allocation problems of position control of three direction and attitude control of three directions of rolling, pitching and deviating of the system are dimensionally-reduced to multiple sub-problems which are problems of the maximum of two degree of freedom. The method comprises engine selection through comparison of a engine vector included angle and a control instruction included angle, calculation of start time and a start time processing method under the situation of boundary exceeding so that a problem of low use efficiency of the engine of a conventional engine use strategy under the situation of strong coupling of attitude and orbit control can be solved, generation of disturbing force and disturbing torque in the position and attitude six-degree-of-freedom control process can be effectively reduced, control precision and stability can be enhanced and propellant consumption can be reduced.

Description

A kind of coupling process of rail control engine

Technical field

The present invention relates to a kind of coupling process of rail control engine, particularly engine configurations makes radial position control be coupled with pitch attitude, orbital plane external position controls situation about being coupled with yaw-position, be applicable to the task that spacecrafts rendezvous etc. needs to carry out relative position and relative Attitude Control for Spacecraft simultaneously, belong to spacecraft attitude control system conceptual design field.

Background technology

The use strategy of spacecraft engine, i.e. the steering order allocation algorithm of engine, directly affect realization and the propellant waste of control action, and the performance of quality on whole control system of therefore its design has very important impact.Particularly for the complicated space mission that such as this generic request control accuracy of spacecrafts rendezvous is high, status is particularly important.

For the steering order allocation algorithm of multi executors High redundancy system, in the fields such as aircraft, boats and ships, submarine, early there is correlative study, have least square method, pseudoinverse technique etc.But the topworks considered in these fields mostly is two-way actuator, namely positive and negative two-way controlled quentity controlled variable can be produced, and the singularity of the steering order assignment problem of spacecraft engine is just, as the one-way of the engine of topworks, namely hard-wired engine can only produce the controlled quentity controlled variable in a direction.At present comparatively ripe engine control mass distribution algorithm mainly contains two kinds: 1. early stage and even be still in fact a kind of look-up table at the traditional instruction allocation algorithm generally used now.It is equivalent to original multifreedom controlling assignment problem to be decomposed into several single-degree-of-freedom problems, carries out command assignment one by one.This method requires, when carrying out thruster configuration design, the thrust/moment in each controlled quentity controlled variable direction to be produced by special thruster (group), is relation one to one between them.Like this when carrying out command assignment, for thrust/torque demand that controller provides, the thruster (group) that so-called " key " is searched can be used, and obtain the working time of every platform thruster.This method has online computing velocity faster, but the comparatively large and control accuracy of propellant expenditure is not done.2. as far back as 1969, just there is the linear programming model of engine control command assignment problem, this multifreedom controlling assignment problem without dimensionality reduction, directly can be solved by existing classic algorithm.The advantage of linear programming technique is that it can try to achieve the optimum solution of command assignment problem, and propellant expenditure is little and control accuracy is high, in addition the versatility of algorithm and robustness all stronger.But with regard to current engineering practice, this algorithm can cause larger burden to CPU, when processing multiple (being greater than 20) engine especially at the same time, cannot meet real-time and in-orbit calculated amount requirement.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art part, provide a kind of can reduce propellant expenditure be suitable for again engineer applied rail control coupling engine use strategy, comprise and carry out engine selection by engine vector angle with comparing of steering order angle, the start duration disposal route in the start calculating of duration and break bounds situation.

Technical solution of the present invention is:

A kind of coupling process of rail control engine, it is characterized in that, comprise the following steps: first spacecrafts rendezvous relates to three shaft positions, the sextuple steering order assignment problem of six degree of freedom control task of attitude is decomposed into and is up to binary subproblem, if two degree of freedom directions in this two degrees of freedom subproblem are respectively F direction and M direction, wherein, F and M direction is two different directions in six degree of freedom direction, is then processed according to the following steps by this two parameter compensator command assignment subproblem;

If for the n platform engine of this two parameter compensator command assignment, be numbered 1 ~ n; Wherein, p is the total engine configurations number of units of spacecrafts rendezvous task, and p >=n >=3, p >=12;

1) calculation engine vector angle, is specially:

If be numbered i, i ∈ 1 ... n}, engine be designated as T at the component in F direction and M direction _iFand T _iM, then the angle in every platform engine and F direction is calculated as follows:

If T _iF>=0 and T _iM>=0, θ _i=arctan (T _iM/ T _iF)

If T _iF<0 and T _iM>=0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF<0 and T _iM<0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF>=0 and T _iM<0, θ _i=2 π+arctan (T _iM/ T _iF)

Thus obtain n platform engine and F angular separation θ ₁~ θ _n;

2) start engine is selected

If the controlled quentity controlled variable that controller exports not is the form of force and moment, but the form of on time, then need the form being turned to power or moment the on time by following formula:

Wherein, the party set when a is Controller gain variations control ability nominal value upwards, △ t is control cycle, and in formula, equivalent control amount is the force and moment after conversion;

Change sextuple for the equivalence of force and moment form steering order vector u into two degrees of freedom subproblem, the steering order component namely on F and M direction is respectively u _fand u _m, form two-dimentional instruction vector [u _fu _m] be calculated as follows with the angle in F direction:

If u _f>=0 and u _m>=0, θ _u=arctan (u _m/ u _f)

If u _f<0 and u _m>=0, θ _u=π+arctan (u _m/ u _f)

If u _f<0 and u _m<0, θ _u=π+arctan (u _m/ u _f)

If u _f>=0 and u _m<0, θ _u=2 π+arctan (u _m/ u _f)

By step 1) middle θ ₁~ θ _nby being arranged in order from small to large, and by θ _uwith θ ₁~ θ _ncompare one by one, if meet following two conditions, then engine mumber of starting shooting is i and j;

Condition 1: θ _i≤ θ _u< θ _j(i, j ∈ 1 ... n})

Condition 2: for k ≠ i and k ≠ j, θ _i< θ _k< θ _jbe false;

3) engine start duration calculation

If step 2) in start engine i and j that select be designated as T respectively at the component in F direction and M direction _iF, T _iMand T _jF, T _jM, then the start duration calculation formula of engine i and j is as follows:

$t_i^{*}=K(T_{\mathrm{jM}}{u}_F-T_{\mathrm{jF}}{u}_M)$

$t_j^{*}=K({-T}_{\mathrm{iM}}{u}_F+T_{\mathrm{iF}}{u}_M)$

K＝T _iFT _jM-T _jFT _iM

Wherein, with for the start duration virtual value of these two engines;

If result of calculation meets and i, j ∈ 1 ... n}, then go to step 5), otherwise go to step 4);

4) start duration break bounds process

For situation, be called start duration break bounds, disposal route is in this case as follows:

2. the start duration of 1 engine is had to be greater than 1

Preferentially meet the demand for control of a direction, if namely the engine on time computing formula then preferentially meeting M or F direction controlling demand is as follows

$t_i^{*}=1,$

$t_j^{*}=(u_X-T_{\mathrm{iX}})/T_{\mathrm{jX}}$

In formula: in subscript, X is M or F; When preferentially meeting M direction, in formula, X is M; When preferentially meeting F direction, in formula, X is F;

After above-mentioned process, the engine that duration of starting shooting if still exist is greater than 1, then duration indirect assignment of being started shooting is 1;

If 2. 2 engine start durations are all greater than 1, then direct is 1 by 2 engine assignment;

5) the start duration actual value of calculation engine i and j

In a control cycle, the true duration that engine i and j starts shooting is provided by formula below:

$\begin{array}{cc}{t}_i=t_i^{*}\&times;\mathrm{\&Delta;t}& t_j=t_j^{*}\&times;\mathrm{\&Delta;t}\end{array}$

Wherein, △ t is control cycle; Wherein t _ifor the start duration of engine i, t _jfor the start duration of engine j;

6) according to t _iand t _j, to the start duration amplitude limit exceeding control cycle, assignment is control cycle, is 0 to the start duration assignment of other n-2 platform engine, completes steering order and distributes.

The present invention's beneficial effect is compared with prior art:

(1) the present invention proposes the engine use strategy of a kind of rail control coupling, compared to conventional decoupling look-up table conventional in engineering, solving of steering order assignment problem brings up to two degrees of freedom from single-degree-of-freedom, the demand of track and gesture stability can be considered simultaneously, therefore engine service efficiency can be improved, reduce the generation of interference force and moment, thus reach raising control accuracy and degree of stability, and reduce the effect of propellant expenditure.

(2) engine of the present invention uses strategy, compared to planning optimizing algorithm conventional in theoretical analysis, solving of steering order assignment problem is reduced to two degrees of freedom from six degree of freedom, eliminate the process in line iteration optimizing, computing velocity is fast, meeting the computing level of current spaceborne computer, is the optimized algorithm of applicable through engineering approaches.

(3) engine proposed by the invention uses strategy, uses the core algorithm of strategy as No. eight, divine boat, No. nine, No. ten airship spacecrafts rendezvous engines, through flight validation in-orbit, has substantially reduced propellant expenditure and improves control accuracy.

Accompanying drawing explanation

Fig. 1 is the FB(flow block) that two degrees of freedom engine of the present invention uses strategy;

Embodiment

Spacecraft body series is defined as: initial point o is the barycenter of spacecraft, and ox axle points to heading along the spacecraft longitudinal axis, and oy axle is along the transverse direction of spacecraft, and perpendicular to the longitudinal axis, point to orbit angular velocity in the other direction, oz axle and ox, oy axle form right-handed system.

The complex control tasks such as spacecrafts rendezvous, need the six degree of freedom control simultaneously carrying out position, attitude.This six-freedom degree is respectively along the gesture stability on the axial position control of ox, oy and oz tri-and the rolling that is axle with ox, oy, oz, pitching, driftage three directions.

Meet the prerequisite of task control Capability Requirement in engine configurations under, appearance rail of the present invention coupling engine uses strategy to be former six degree of freedom is controlled allocating task to be decomposed into some most high-freedom degrees be the subtask of two, then solves steering order distribution subproblem respectively.

Spacecrafts rendezvous six degree of freedom steering order assignment problem dimensionality reduction is become multiple single-degree-of-freedom and two degrees of freedom subproblem.Single-degree-of-freedom subproblem solves by traditional look-up table, to the two degrees of freedom subproblem that may relate to track and gesture stability simultaneously, first zoning is come by calculating each motor power vector with axial angle, then the two parameter compensator amount provided according to controller judge this controlled quentity controlled variable affiliated area with the angle of axis, thus select the engine of start, then their start duration ratio is calculated according to the component size of start engine on these two degree of freedom directions, and carry out the process of break bounds situation, finally obtain real engine start duration according to control cycle.

Below embodiment is set forth.

(1) dimensionality reduction of six degree of freedom problem

If spacecraft is configured with p (p >=12) individual engine.According to the coupling condition of engine at each controlling party component upwards, former six degree of freedom steering order assignment problem is decomposed, be decomposed into several two degrees of freedom problems and single-degree-of-freedom problem, and list whole engines that each subproblem carries out corresponding to steering order distribution.Concrete steps are as follows:

1) the force and moment component that every platform engine can produce on six-freedom degree direction is listed.

2) will in certain both direction component comparatively outstanding, and the engine that component is very little is in the other direction chosen, and the engine with two equidirectional components is divided into one group, and namely this both direction forms a two degrees of freedom subproblem.If there is not such engine, then this engine configurations is not suitable for engine use strategy described in this patent.

3) establish this two degrees of freedom direction to be respectively F direction and M direction, F direction and M direction to be in above-mentioned six degree of freedom direction two different directions.Engine for this two parameter compensator command assignment has n (p >=n >=3).The power that can produce this n platform engine in F direction and M direction or moment components are written as following matrix form:

$A=\left[\begin{array}{cccc}{T}_{1F}& T_{2F}& ...& T_{\mathrm{nF}}\\ T_{1M}& T_{2M}& ...& T_{\mathrm{nM}}\end{array}\right]$

Wherein, T _iFrepresent the power/moment components of i-th engine generation in the directionf, T _iMrepresent power/moment components that i-th engine produces on M direction, i ∈ 1 ... n}.

By exchanging A matrix column, A matrix is turned to A=[A ₁| A ₂], make wherein A ₁it is the row non-singular matrix of 2 × 2 dimensions.Get transformation matrix nonsingular transformation is carried out to matrix A, turns to form.Wherein I ₂for two-dimentional unit matrix.

If can bear, then this two degrees of freedom subproblem of Algorithm for Solving in available step (2).Otherwise this engine configurations is not suitable for engine described in this patent uses strategy.

Matrix can bear and be defined as: for matrix n>=1, if constraint inequation group

$\stackrel{\&OverBar;}{A}x<0,x\&Element;R_{+}^n$

There is solution, then claim can bear, wherein vector is less than its all elements of zero finger and is all less than zero.

4), after determining all two parameter compensator subproblems, remaining degree of freedom direction is as single-degree-of-freedom issue handling.By in remaining engine, directly can provide or provide the engine of corresponding single-degree-of-freedom direction controlling power or moment or cluster engine to pick out volume by the mode that engine combines is one group, as the engine combination that this single-degree-of-freedom problem is corresponding.

(2) two parameter compensator command assignment subproblem is solved

If for n (p >=n >=3) the platform engine of this two parameter compensator command assignment, be numbered 1 ~ n.

Fig. 1 is the FB(flow block) that two degrees of freedom engine of the present invention uses strategy, gives the process flow diagram of engine using method, comprises the steps:

1) calculation engine vector angle, is specially:

If be numbered i (i ∈ 1 ... n}) engine be designated as T at the component in F direction and M direction _iFand T _iM, then the angle in every platform engine and F direction is calculated as follows:

If T _iF>=0 and T _iM>=0, θ _i=arctan (T _iM/ T _iF)

If T _iF<0 and T _iM>=0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF<0 and T _iM<0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF>=0 and T _iM<0, θ _i=2 π+arctan (T _iM/ T _iF)

Thus obtain n platform engine and F angular separation θ ₁~ θ _n.

2) start engine is selected

To each control cycle, the sextuple steering order that controller provides contains position control amount on above-mentioned three directions and attitude control quantity demand.If the controlled quentity controlled variable that controller exports not is the form of force and moment, but the form of on time, then need the form it being turned to power or moment by following formula:

Wherein, the party set when a is Controller gain variations control ability nominal value upwards, △ t is control cycle; Equivalent control amount is force and moment form, if controller exports as force and moment form, directly carries out following steps:

If the equivalence obtaining force and moment form sextuple steering order vector u, the steering order component of two degrees of freedom subproblem namely on F and M direction of its correspondence is respectively u _fand u _m, form two-dimentional instruction vector [u _fu _m] be calculated as follows with the angle in F direction:

If u _f>=0 and u _m>=0, θ _u=arctan (u _m/ u _f)

If u _f<0 and u _m>=0, θ _u=π+arctan (u _m/ u _f)

If u _f<0 and u _m<0, θ _u=π+arctan (u _m/ u _f)

If u _f>=0 and u _m<0, θ _u=2 π+arctan (u _m/ u _f)

By step 1) middle θ ₁~ θ _nby being arranged in order from small to large, and by θ _ucompare one by one with them.If meet following two conditions:

①θ _i≤θ _u<θ _j(i,j∈{1,...n})

2. for k ≠ i and k ≠ j, θ _i< θ _k< θ _jbe false

Engine mumber of then starting shooting is i and j.

3) engine start duration calculation

If step 2) in start engine i and j that select be designated as T respectively at the component in F direction and M direction _iF, T _iMand T _jF, T _jM, then their start duration calculation formula is as follows:

$t_i^{*}=K(T_{\mathrm{jM}}{u}_F-T_{\mathrm{jF}}{u}_M)$

$t_j^{*}=K({-T}_{\mathrm{iM}}{u}_F+T_{\mathrm{iF}}{u}_M)$

K＝T _iFT _jM-T _jFT _iM

Wherein, with for the start duration virtual value of these two engines.

If result of calculation meets and i, j ∈ 1 ... n}, then go to step 5).Otherwise go to step 4).

4) start duration break bounds process

Controller export within the scope of control ability, step 3) result of calculation scope be generally i ∈ 1 ... n}.3 of step (1)) ensure that for situation, be called start duration break bounds, disposal route is in this case as follows:

1. the start duration of 1 engine is only had to be greater than 1

Preferentially can meet the demand for control (such as gesture stability demand) of a direction.If i.e. t _i ^*>1, then preferentially meet M or F direction controlling demand, and when preferentially meeting M direction, engine on time computing formula is as follows, preferentially meets F direction and only the subscript M in following formula need be changed into F;

After above-mentioned process, the engine that duration of starting shooting if still exist is greater than 1, then duration indirect assignment of being started shooting is 1.

If 2. 2 engine start durations are all greater than 1, then direct is 1 by their assignment.

5) start duration actual value is calculated

In a control cycle, the true duration of engine start is provided by formula below:

$\begin{array}{cc}{t}_i=t_i^{*}\&times;\mathrm{\&Delta;t}& t_j=t_j^{*}\&times;\mathrm{\&Delta;t}\end{array}$

Wherein, △ t is control cycle.

(3) solve single-degree-of-freedom steering order and distribute subproblem

Single-degree-of-freedom command assignment subproblem is divided into two kinds of situations:

If the steering order 1. on this degree of freedom direction is input as start duration, then the direct on time assignment for changing engine corresponding to subproblem or cluster engine.

If the controlled quentity controlled variable 2. on this degree of freedom direction is input as power/moment, then by it divided by its corresponding engine or cluster engine power/moment in the direction in which, obtain start duration virtual value, and then be multiplied by control cycle, truly being started shooting duration, is the engine assignment of correspondence.

(4) obtain the start duration of each start engine by above-mentioned steps, be control cycle to the start duration indirect assignment exceeding control cycle, be 0 to the start duration assignment of engine of not starting shooting, steering order is assigned.

The content be not described in detail in instructions of the present invention belongs to the known technology of professional and technical personnel in the field.

Claims (1)

1. the coupling process of a rail control engine, it is characterized in that, comprise the following steps: first spacecrafts rendezvous relates to three shaft positions, the sextuple steering order assignment problem of six degree of freedom control task of attitude is decomposed into and is up to binary subproblem, if two degree of freedom directions in this two degrees of freedom subproblem are respectively F direction and M direction, wherein, F and M direction is two different directions in six degree of freedom direction, is then processed according to the following steps by this two parameter compensator command assignment subproblem;

If for the n platform engine of this two parameter compensator command assignment, be numbered 1 ~ n; Wherein, p is the total engine configurations number of units of spacecrafts rendezvous task, and p >=n >=3, p >=12;

1) calculation engine vector angle, is specially:

If be numbered i, i ∈ 1 ... n}, engine be designated as T at the component in F direction and M direction _iFand T _iM, then the angle in every platform engine and F direction is calculated as follows:

If T _iF>=0 and T _iM>=0, θ _i=arctan (T _iM/ T _iF)

If T _iF<0 and T _iM>=0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF<0 and T _iM<0, θ _i=π+arctan (T _iM/ T _iF)

If T _iF>=0 and T _iM<0, θ _i=2 π+arctan (T _iM/ T _iF)

Thus obtain n platform engine and F angular separation θ ₁~ θ _n;

2) start engine is selected

If the controlled quentity controlled variable that controller exports not is the form of force and moment, but the form of on time, then need the form being turned to power or moment the on time by following formula:

Wherein, the party set when a is Controller gain variations control ability nominal value upwards, △ t is control cycle, and in formula, equivalent control amount is the force and moment after conversion;

Change sextuple for the equivalence of force and moment form steering order vector u into two degrees of freedom subproblem, the steering order component namely on F and M direction is respectively u _fand u _m, form two-dimentional instruction vector [u _fu _m] be calculated as follows with the angle in F direction:

If u _f>=0 and u _m>=0, θ _u=arctan (u _m/ u _f)

If u _f<0 and u _m>=0, θ _u=π+arctan (u _m/ u _f)

If u _f<0 and u _m<0, θ _u=π+arctan (u _m/ u _f)

If u _f>=0 and u _m<0, θ _u=2 π+arctan (u _m/ u _f)

By step 1) middle θ ₁~ θ _nby being arranged in order from small to large, and by θ _uwith θ ₁~ θ _ncompare one by one, if meet following two conditions, then engine mumber of starting shooting is i and j;

Condition 1: θ _i≤ θ _u< θ _j(i, j ∈ 1 ... n})

Condition 2: for k ≠ i and k ≠ j, θ _i< θ _k< θ _jbe false;

3) engine start duration calculation

If step 2) in start engine i and j that select be designated as T respectively at the component in F direction and M direction _iF, T _iMand T _jF, T _jM, then the start duration calculation formula of engine i and j is as follows:

$t_i^{*}=K(T_{\mathrm{jM}}{u}_F-T_{\mathrm{jF}}{u}_M)$

$t_j^{*}=K(-T_{\mathrm{iM}}{u}_F+T_{\mathrm{iF}}{u}_M)$

K＝T _iFT _jM-T _jFT _iM

Wherein, with for the start duration virtual value of these two engines;

If result of calculation meets and i, j ∈ 1 ... n}, then go to step 5), otherwise go to step 4);

4) start duration break bounds process

For situation, be called start duration break bounds, disposal route is in this case as follows:

1. the start duration of 1 engine is had to be greater than 1

Preferentially meet the demand for control of a direction, if namely the engine on time computing formula then preferentially meeting M or F direction controlling demand is as follows

$t_i^{*}=1,$

$t_j^{*}=(u_X-T_{\mathrm{iX}})/T_{\mathrm{jX}}$

In formula: in subscript, X is M or F; When preferentially meeting M direction, in formula, X is M; When preferentially meeting F direction, in formula, X is F;

After above-mentioned process, the engine that duration of starting shooting if still exist is greater than 1, then duration indirect assignment of being started shooting is 1;

If 2. 2 engine start durations are all greater than 1, then direct is 1 by 2 engine assignment;

5) the start duration actual value of calculation engine i and j

In a control cycle, the true duration that engine i and j starts shooting is provided by formula below:

$\begin{array}{cc}{t}_i=t_i^{*}\&times;\mathrm{\&Delta;t}& t_j=t_j^{*}\&times;\mathrm{\&Delta;t}\end{array}$

Wherein, △ t is control cycle; Wherein t _ifor the start duration of engine i, t _jfor the start duration of engine j;

6) according to t _iand t _j, to the start duration amplitude limit exceeding control cycle, assignment is control cycle, is 0 to the start duration assignment of other n-2 platform engine, completes steering order and distributes.