WO2018108905A1

WO2018108905A1 - Method and device for position control of a spacecraft

Info

Publication number: WO2018108905A1
Application number: PCT/EP2017/082419
Authority: WO
Inventors: Stefanos Fasoulas; Georg Herdrich; Tobias Schateikis
Original assignee: Universität Stuttgart
Priority date: 2016-12-13
Filing date: 2017-12-12
Publication date: 2018-06-21
Also published as: DE102016224816A1; DE102016224816B4

Abstract

The invention relates to a method and to a device for position control of a spacecraft (1). In the method, a force is exerted on the spacecraft (1) by emitting at least one directed beam (7) of electromagnetic radiation having sufficient power for position control, leading to a change in the position and/or orientation of the spacecraft (1) in space. The electromagnetic radiation is generated by one or more light-emitting diodes (8) arranged on the spacecraft (1), and effects a change in the position and/or orientation of the spacecraft (1) by emitting said beam (7) from the spacecraft (1). Precise position control of the spacecraft (1) can be achieved by controlling the emission direction and emission power. The method and the device enable fuel-free position control with maximum precision.

Description

Method and device for position control of a

Spacecraft

Technical application

The present invention relates to a method for position control of a spacecraft, in which by at least one directed beam of electromagnetic radiation sufficient for the position control power is exerted on the spacecraft, which leads to a change of position and / or

Orientation of the spacecraft in space leads. The invention also relates to a device arranged on the spacecraft for attitude control. Spacecraft may be, for example, artificial satellites, spacecraft, spaceships, spacecraft, spacecaps or space stations.

Various spacecraft missions planned for space use, such as

Satellites or probes, both in the commercial and scientific sectors increasingly have complex requirements for highly accurate stabili ^¬ sierende orientation of the spacecraft and the instruments in space on board. In addition to a fine torque resolution and pulse capability, the fast control-specific responsiveness of the position control system used on correction ^{commands is} decisive. In addition to an energy and

Fuel-optimized generation of control thrusts should often be as free of contamination as possible Technology can be used to influence other systems of the spacecraft

avoid.

State of the art

Known active attitude control and stabilization techniques use control thrusters that require fuel to generate a spacecraft torque. The to

Torque generating force is required

for example, by oxidation of the Treibstoffedukte and subsequent expansion of the combustion gases

taught. Likewise, by means of high electric fields, an ionized fluid (gas, liquid) can be accelerated and expelled. In any case, results in these techniques, the position-regulating torque generation from the recoil principle of

accelerated, mass-laden fuel.

Another known possibility for attitude control and stabilization of satellites is based on

different variants of reaction or twisting wheels. These build up a stabilizing or compensating angular momentum through the adaptive rotational motion of a flywheel. However, they have a maximum value of their inducible

Angular momentum and must therefore with the help of

Thrusters or other angular momentum generators,

For example, by magnetic gate, be desaturated from time to time. Many of those in use so far

Technologies for active attitude control of spacecraft use fuel (= mass) for torque ^¬ generation. This fuel must be carried along from the beginning of the mission and is also available only to a limited extent over the planned mission duration. Consequently, these criteria influence the take-off mass and mission-related service life of the spacecraft ^¬ body. A major disadvantage of these technologies is therefore the need to carry and store the limited amount of fuel available to generate torque.

Even with the initially fuel-free position control by means of reaction wheels can not be dispensed with in many cases on a combination with thrusters as a pulse because the masses must be desaturated when reaching a maximum rotational moment. This also results in a larger one

System complexity. Furthermore, make the rotating

Massive high demands on the mechanical structure of the spacecraft, as mechanical loads such as vibrations and vibration must be intercepted, for example, a negative impact on

minimize existing sensors for scientific experiments.

Another disadvantage of these common concepts is that the torque resolution and the reaction times of the position control system, for example ^{¬ represent} by the startup behavior of reaction wheels, limiting factors with regard to the required accuracy. Future planned missions for space-based scientific experiments place demands for the torque in the (sub-) micro-newtonmeters area, which with existing

Technology can not be met or only with great extra effort.

From DE 19848737 C2 a method for position and orbit control of satellites using electromagnetic radiation is known. In this method, reflecting surfaces are formed on the satellite which are electromagnetic with a directed beam

Radiation of a terrestrial or on another satellite radiation source are irradiated as needed to the location and / or trajectory of the

To influence satellites by the momentum transfer during reflection. However, such a technique requires either a visual connection between earth and satellite or another spacecraft and is also disturbed by alternating losses due to atmospheric influences in the case of an earthbound radiation source.

The object of the present invention is a method for attitude control of a spacecraft and a corresponding device for

Provide attitude control on a spacecraft, which allow a high-precision attitude control of the spacecraft and need no fuel.

Presentation of the invention

The object is achieved with the method and the device arranged on the spacecraft according to the

Claims 1 and 8 solved. advantageous Embodiments of the method and the device are the subject of the dependent claims or can be found in the following description and the embodiment.

In the proposed method for attitude control of a spacecraft is by emission of at least one directional beam of electromagnetic radiation with sufficient for a position control

Radiation power exerted a force on the spacecraft, which leads to a change in the position and / or orientation of the spacecraft in space. The electromagnetic radiation is thereby generated with one or more light emitting diodes (LEDs) arranged on the spacecraft. The change of position or orientation of the spacecraft then takes place at

Demand by radiation of the at least one beam of electromagnetic radiation from the spacecraft. About the direction of the radiation of the beam is the

Direction of the force acting on the spacecraft fixed force. According to basic physical principles, the magnitude of the force corresponds to 3.3 x 10 ^-9 Newton per watt of radiated electromagnetic power For the change in the orientation of the spacecraft, a torque is generated, which essentially consists of the recoil impulse of the emitted electromagnetic waves via a lever arm In this case, the lever arm corresponds to the distance of the radiation location from a main axis of the spacecraft With a radiation power of 1 kW with a lever arm of one meter, a torque of 3.3 μΝιτι results. The attitude control in the proposed method preferably takes place by controlling the radiation direction and / or the radiation power of the at least one beam of electromagnetic radiation from the spacecraft. The direction of the torque and thus the orientation change of the spacecraft can be determined by the choice of the radiation direction. The radiated power can be used to influence the size of the respectively exerted torque.

In principle, any type of electromagnetic radiation can be used for the proposed method

can be used, which can be generated with LEDs, in particular IR, VIS or UV radiation. Preferably, a range of electromagnetic radiation is used for the LEDs are available with which the radiation with the lowest possible losses and / or as quickly as possible from stored electrical

Energy can be generated. In principle, you can

Instead of LEDs, other light sources, preferably ^¬ with comparably low energy consumption, are used.

The radiation can be generated with only one or with several LEDs. The radiation of several LEDs can be bundled into a single beam. It is also possible to generate a plurality of beams which are radiated, for example, in different spatial directions. Preferably, the at least one beam of electromagnetic radiation is before the

Radiation guided by one or more Strahlablenk- and / or beam guiding elements on the spacecraft. The radiation can be by using one or a plurality of movable beam deflecting elements in almost any direction or via correspondingly fixed set deflection in fixed predetermined

Directions take place, in which case, for example, the beam via beam switches between the respective

Beam deflecting elements can be switched.

Of course, other embodiments are possible to the generated on the spacecraft beam of electromagnetic radiation in different

To radiate spatial directions. The spatial direction of the radiation is chosen in each case so that the desired change in position of the spacecraft is achieved by the radiation. In a preferred embodiment, the electromagnetic radiation is generated via a plurality of LEDs. The control of Abradrahlleistung can then be done for example by switching on and off one or more of these LEDs. This makes it possible to generate extremely small thrusts or torques that could not previously be achieved with conventional technology. This allows the attitude control of spacecraft with extremely high alignment accuracy. The electrical energy for generating the

Electromagnetic radiation can be obtained, for example, primarily with the aid of photovoltaic cells. In order to compensate for any phases of insufficient solar radiation, may additionally

Rechargeable secondary batteries are used. Supercapacitors can also be used for short-term power peaks. Photovoltaic and secondary batteries or supercapacitors but currently non-exclusive possible ^¬ speeds preferred is for primary production and intermediate storage of electrical power. Thus, for example, radioisotope generators, reactors, fuel cells above for primary production and conventional Kondensa ^¬ motors, regenerative fuel cells or momentum wheels, in particular two opposite spin wheels for which, if necessary . necessary temporary storage conceivable.

Of course, any combination of the above components are possible.

The for the implementation of the procedure

trained device that is installed on the spacecraft, correspondingly has one or more LEDs for generating electromagnetic radiation sufficient for the position control, a

Arrangement for forming and / or guiding a beam of the electromagnetic radiation and an emitting device, via which a radiation of the beam of electromagnetic radiation from the spacecraft in different directions is possible. The

Device preferably has a control for the radiation of the beam of the electromagnetic

Radiation for attitude control, in particular a

Control with which the emission direction and / or the Abstrahlleistung of the beam electro ^¬ magnetic radiation according to the desired position control of the spacecraft can be controlled. The proposed method and the associated

Device use a fuel-free position control, since the torque is generated by emission of electromagnetic waves. Because this kind of Torque generation is not dependent on the implementation of bulk fuel, can on

corresponding subsystem components for its

Carrying, storage and its implementation are omitted for torque generation. This results in a lower mass of the spacecraft, a lower complexity and a longer service life of the attitude control system. This also increases the mission ^{lifetime of} the spacecraft. The method and apparatus allow a shorter reaction time ^¬ for correction requests to ground afflicted fuel systems, the inherent latency, by promoting, Expansion in an engine and

possibly caused by chemical reactions, does not occur in the present process. By using electromagnetic radiation as a pulse generator can be very short and extremely precise

Minimal pulses are generated, which are far superior to the performance ^¬ specifications of previous position control technologies such as reaction wheels or cold gas engines. The achievable control ^¬ precision makes it very challenging space missions possible. Another advantage is the clear

reduced system complexity due to the elimination of the fuel delivery system. As a result, significantly lower costs for the position control system and increased reliability of the position control are achieved.

Finally, this also becomes a potential

Contamination of the spacecraft due to backflowing fuel components excluded. Areas of application of the proposed method and the associated device are all spacecraft, which is a very precise attitude control

need. One example is the ESA's planned LISA mission to detect gravitational waves, which involves a fine alignment of laser beams from three satellites over a distance of several

Million kilometers required.

Brief description of the drawings

The proposed method and the associated device will be explained in more detail using an exemplary embodiment in conjunction with the drawings. 1 shows an example of a spacecraft having a position control device according to the invention; and an example of the generation and

Radiation of the beam of electro ^¬ magnetic radiation from a

Spacecraft.

Ways to carry out the invention

Figure 1 shows a schematic representation of an example of a spacecraft with a position control device according to the present invention. The spacecraft 1 has in this example on its outside photovoltaic modules 2 as a primary energy source via which the power supply of the electric Components of this spacecraft takes place. to

Caching of the energy generated by the photovoltaic modules 2 is a primary energy storage 3, for example in the form of Li-ion batteries on the spacecraft 1 is arranged. For high power requirements, an additional energy store 4 is provided in this example, which is formed from supercapacitors. Furthermore, a thrust or torque generating unit 5 is arranged on an outer side of the spacecraft ^¬ body 1, which is shown enlarged again in the right part of the figure. This push or

Torque generating unit 5 has a distance R from the main axis 6 of the spacecraft 1. The thrust ^¬ or torque generating unit 5 is part of the apparatus of the invention and is used for emitting a beam of electromagnetic radiation from the 7

Spacecraft. In the present example, the thrust generating unit 5 enables the

Radiation of the beam 7 electromagnetic radiation in five spatial directions, each about a

Distinguish angles of 90 ° or 180 °. Depending on

Radiation direction of the spacecraft 1 learns due to the distance R of the thrust or torque ^¬ generating unit 5 of the main axis 6 of the

Spacecraft 1, a torque by which the position of the spacecraft is changed. About a control of the radiation direction and the radiation power can thus in dependence on appropriate

Control parameters take place an exact position control of the spacecraft 1. FIG. 2 shows an example of the generation of the beam 7 of electromagnetic radiation in one

Device, as it can be used in the spacecraft 1 of Figure 1. This example is called

Radiation source an LED array 8 used. Such an LED array has a high efficiency. The electrical energy required for generating radiation can, for example, directly from solar cells or

Photovoltaic modules, via batteries or even at very high power requirements for generating high torques from supercapacitors (supercaps) are retrieved, as these are also indicated by way of example in Figure 1. About individual glass fibers 9 and a Kolimatoreinheit 10 takes place in this example, a bundling of the radiation of the individual LEDs to form an optical beam 7. The

Beam is then radiated in this example via a controllable reflector 11 from the spacecraft.

This controllable reflector 11, which can be controlled, for example, mechanically and / or optically, enables radiation in almost any desired

Direction. On the number of activated LEDs of the LED array 8 can easily a modulation of the generated thrust or torque over several

Magnitudes take place.

Reference sign list

Spacecraft

photovoltaic modules

Primärenergiespeieher

additional energy storage

Thrust or torque generating unit

Main axis of the spacecraft

beam

LED array

glass fibers

collimator

Controllable reflector

Claims

claims

A method for position control of a spacecraft (1), in which by at least one directional beam (7) electromagnetic radiation sufficient for the position control power is exerted on the spacecraft (1), which leads to a change of position and / or

Orientation of the spacecraft (1) leads in space,

characterized,

that the electromagnetic radiation with one or more on the spacecraft (1)

arranged light emitting diodes (8) is generated and the change of position and / or orientation of the spacecraft (1) by radiation of the

at least one beam (7) of electromagnetic radiation from the spacecraft (1) is effected.

Method according to claim 1,

characterized,

that an emission direction of the at least one beam (7) of electromagnetic radiation from the spacecraft (1) and / or a Abstrahlungs- performance of the at least one beam (7) electromagnetic ^¬ radiation from the spacecraft (1) is controlled to carry out the position control.

3. The method according to claim 2,

characterized,

that the electromagnetic radiation with several arranged on the spacecraft (1)

Light-emitting diodes is generated and the control of Abradrahlleistung done by switching on and off one or more of these light-emitting diodes.

Method according to one of claims 1 to 3, characterized

that the beam (7) of electromagnetic radiation before the emission by one or more

Beam deflecting and / or beam guiding elements (9, 10) on the spacecraft (1) is guided.

Method according to one of claims 1 to 4, characterized

that required for the generation of electromagnetic radiation electrical energy is generated by photovoltaic cells (2) on the spacecraft (1).

Method according to claim 5,

characterized,

that the electrical energy required for generating the electromagnetic radiation in rechargeable batteries (3) and / or

Supercapacitors (4) is cached.

Method according to one of claims 1 to 6, characterized

in that the electromagnetic radiation is generated with one or more light-emitting diode arrays (8). Device for position control of a spacecraft (1), which is arranged on the spacecraft (1) and at least

- one or more light emitting diodes or light emitting diode array (8) for generating electromag netic radiation ^¬ sufficient for the position control performance,

an arrangement (9, 10) for shaping and / or guiding a beam (7) of the electromagnetic radiation, and

- An emission device (5, 11) for the radiation of the beam (7) electromagnetic radiation from the spacecraft (1) in different directions of discharge has.

Device according to claim 8,

characterized,

in that it has a control with which the radiation direction of the beam (7) of electromagnetic radiation from the spacecraft (1) and / or a radiation power of the beam (7) of electromagnetic radiation from the spacecraft (1) for the attitude control can be controlled. 10. Apparatus according to claim 8 or 9,

characterized,

in that photovoltaic cells (2) are arranged on the spacecraft (1) with which electrical energy required for generating the electromagnetic radiation is generated.

Device according to claim 10,

characterized, in that rechargeable batteries (3) and / or supercapacitors (4) are arranged on the spacecraft (1) in which the electrical energy required for generating the electromagnetic radiation is intermediately stored.