EA037754B1 - Spacecraft movement control method - Google Patents

Abstract

The invention relates to combined control of centre of mass movement and angular orientation of spacecrafts using low-thrust engines. The engines are arranged in pairs symmetrically to the plane of axes of roll and yaw of the spacecraft, and the lines of action of their rods pass through the centre of mass of the spacecraft and are directed at an angle to the main axes of inertia of the spacecraft. The engines of pair are deviated from the plane of axes of pitch and roll by some angle, and from the plane of axes of pitch and yaw - at some other angle. The engines that create opposite transversal accelerations are successively turned on. Orbit section and duration of required engine activation are selected depending on current position of orbit inclination vector. Traction direction is selected based on minimum flow rate of working medium with minimum effect on spacecraft structure elements. The technical results are optimization of working medium flow rate for spacecraft retention by latitude and longitude, reduction of mass of electric propulsion plant and reduction of disturbing moments caused by action of engine jets.

Description

The invention relates to the field of space technology and can be used to control the movement of spacecraft (SC).

At present, various means and methods of spacecraft motion control are known, which are used for spacecraft orbit correction, spacecraft stabilization and orientation. Control systems can differ significantly in design, power consumption, type of executive bodies, depending on the control tasks to be solved, the spacecraft mass and orbit of its motion, as well as the duration of corrective maneuvers. The spacecraft control system can simultaneously control the motion of the spacecraft center of mass and control the spacecraft motion relative to its spacecraft center of mass.

The closest analogue is the Method of spacecraft motion control and control system (patent for invention RU 2309876 C1). A method for controlling the spacecraft motion, which consists in controlling the motion of the spacecraft's center of mass and in controlling the spacecraft's angular orientation in space, including a control action on the spacecraft by turning on at least one low-thrust jet engine of the spacecraft propulsion system, which creates a thrust vector relative to the three main orthogonal axes of inertia of the spacecraft ... Control actions are created using low-thrust jet engines located in a common spacecraft mounting plane, orthogonal to one of its planes of inertia, with an angular displacement between the nearest low-thrust jet engines.

A number of significant disadvantages characteristic of the prototype are as follows:

1) the efficiency of using the thrust given in the examples of the implementation of the invention is achieved through the use of two low-thrust jet engines, which leads to an increase in the required power of the spacecraft power plant, since orbit correction takes 1.5-3 hours per day, the rest of the time the power of the power plant will not be used, which leads to non-optimal design of the spacecraft;

2) low-thrust jet engines are placed evenly on the spacecraft body. During the creation of the control action, the jets of low-thrust jet engines will create disturbing moments when acting on the SC elements (solar batteries, antennas, etc.), which must be compensated for when controlling the angular position of the SC and, accordingly, require additional expenditure of SC resources (fuel);

3) increased spacecraft mass due to the increased number of engines (by condition - at least five).

The tasks to be solved by the claimed invention are the implementation of correction and retention of the spacecraft in orbit with minimum fuel consumption;

reduction of disturbing moments created by low-thrust engines when creating a control action;

decrease in the mass of the spacecraft.

To solve the set tasks, a method is proposed for controlling the spacecraft motion, which consists in controlling the motion of the spacecraft's center of mass, which includes a control action on the spacecraft by turning on one (out of the total number) low-thrust jet engine of the spacecraft propulsion system, which creates a thrust vector relative to the three main orthogonal axes of inertia of the spacecraft. In this case, the control action is created taking into account the compensation of the influence of external disturbing forces by means of sequential switching on of low-thrust engines located at an angle relative to the plane of the pitch and roll axes, as well as the plane of the pitch and yaw axes of the spacecraft, at a given time, which depends on the location of the spacecraft on orbit. In this case, the choice of the orbital section for switching on, as well as the choice of switching on a certain low-thrust engine and the duration of its operation depend on the current position of the spacecraft inclination vector, and the direction of the thrust vectors is chosen based on the minimum fuel consumption and the minimum effect on the spacecraft elements. Also, there are no disturbing moments and forces from the inclusion of each low-thrust engine. In particular cases of implementation of the invention, low-thrust jet engines can be plasma, ionic, electric-arc.

The proposed method of spacecraft motion control in comparison with the closest analogue allows achieving the following technical results:

to reduce fuel consumption during correction with the possibility of increasing the spacecraft service life with the same reserve or, at the same service life, to realize the possibility of increasing the payload mass using a smaller fuel supply;

to optimize the correction and retention of the spacecraft in orbit by eliminating the need to compensate for off-design disturbing effects during the operation of low-thrust engines;

to reduce the number of low-thrust engines to four (the prototype must have at least five), thereby reducing the mass and cost of the spacecraft.

Application of this method of spacecraft motion control also allows:

to carry out, during operations to control the motion of the spacecraft's center of mass, operations to damp the angular momentum (unloading) of inertial controls, for example, gyroscopic power stabilizers (flywheels);

make programmed rotations of the spacecraft during orientation.

- 1 037754

The essence of the invention is illustrated by drawings, which show:

in fig. 1 - a schematic view of the spacecraft is shown;

in fig. 2 - schematically shows the spacecraft body with installed engines (top view);

in fig. 3 - schematically shows the spacecraft body with installed engines (side view);

in fig. 4 schematically shows a particular case of implementation of the invention at different angles of installation of engines.

A method for controlling the motion of spacecraft 1, which consists in controlling the motion of the center of mass of spacecraft 1, including a control action on spacecraft 1 by turning on one (out of the total number) of a low-thrust jet engine 2 of the propulsion system of spacecraft 1, which creates a thrust vector relative to the three main orthogonal axes of inertia of spacecraft 1 . Moreover, the control action is created taking into account the compensation of the influence of external disturbing forces by means of sequential switching on of low-thrust engines 2 located at an angle a 3 relative to the plane of the pitch and roll axes, as well as at an angle β 4 relative to the plane of the pitch and yaw axes of spacecraft 1 at a given moment time, which depends on the location of spacecraft 1 in orbit. In this case, the choice of the orbital section for switching on, as well as the choice of switching on a certain low-thrust engine 2 and the duration of its operation depend on the current position of the inclination vector of spacecraft 1, and the direction of the thrust vectors is chosen based on the minimum fuel consumption and the minimum effect on the spacecraft 1 elements. In practice, the angles a 3, β 4 are in the range from 0 to 45 °. Also, there are no disturbing moments and forces from the inclusion of each low-thrust engine. In particular cases of implementation of the invention, low-thrust jet engines can be plasma, ion, electric arc.

Obtaining technical results is guaranteed when applying the below strategy of keeping the spacecraft in geostationary orbit in latitude and longitude.

The strategy of carrying out corrections of the spacecraft holding in latitude and longitude should minimize fuel consumption. The analysis shows that the main fuel consumption in the interval of long-term operation of the spacecraft (15 and more years) is associated with its retention in latitude.

To save the velocity impulse, all short-period components of the disturbance of the inclination vector are separated into an uncorrected group. Latitude hold corrections provide compensation for the secular component of the inclination vector change caused by lunisolar disturbances.

The directions of the thrust vectors of the engines are selected based on the minimum fuel consumption over the active life and the minimum influence of the engines on the spacecraft elements.

To correct the latitude, such orbital sections and the duration of operation of low-thrust engines are selected in order to optimally change the inclination vector. On each orbit of the flight, there are theoretically two such orbital sections (spaced 180 ° apart in the latitude argument). In this case, the duration of the operation of the engines in both sections is the same, and the directions of the corrective accelerations in the North - South direction are opposite. The choice of the orbit section, the duration of the engines operation depend on the current position of the spacecraft inclination vector and the parameters of the holdover strategy.

Keeping the spacecraft in longitude is reduced to corrections of the spacecraft orbital period and eccentricity of the orbit, which should compensate for the influence of disturbing forces, first of all, the noncentrality of the Earth's gravitational field and light pressure.

The arrangement of the motors is such that when the inclination vector is corrected, the eccentricity vector and the sidereal period also change. The necessary change in the period of revolution is provided by either choosing a motor (having the required sign of transverse acceleration) or sequential switching on of two motors having opposite transverse accelerations.

As for the control of the eccentricity vector, the following algorithm can be used:

a) on the orbit, inclination corrections are planned with one turn-on, which ensures a change in the period of revolution in the desired direction. Of the two possible options (engine of the north or engine of the south direction), that part of the orbit is selected where, at least, the eccentricity value does not deteriorate;

b) if one engine does not provide the required change in the period of revolution, then the maneuver is calculated for a pair of engines of the same direction to the north (south). In this case, from two possible pairs of inclusions (motors of the north or south direction), the more optimal for eccentricity is selected;

c) if the inclination corrections are not enough and the eccentricity is greater than the specified threshold value, then on the orbit it is planned to correct the eccentricity by two inclusions spaced 12 hours apart. In this case, the period of revolution and the eccentricity of the orbit simultaneously change.

Claims (2)

CLAIM 1. A method for controlling the movement of a spacecraft, which consists in controlling the movement of the center of mass of the spacecraft by means of low-thrust jet engines of its propulsion system, creating a thrust vector relative to the three main axes of inertia of the spacecraft, characterized in that the control action is formed taking into account the compensation of external disturbing forces by sequential switching on of low-thrust engines, creating opposite transverse accelerations and located at an angle relative to the plane of the pitch and roll axes, as well as the plane of the pitch and yaw axes of the spacecraft at a given moment in time, while choosing an orbit section to turn on a certain low-thrust engine and the duration of its operation carried out depending on the current position of the orbital inclination vector, choosing the direction of the thrust vectors of the engines based on the minimum fuel consumption with a minimum impact on the elements of the spacecraft. 2. The method according to claim 1, characterized in that low-thrust jet engines can be plasma, ionic, electric-arc.