DE3329670A1 - OPTICAL POSITION SENSOR FOR A SATELLITE - Google Patents

Description

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The invention relates to an optical position sensor for a satellite according to the preamble of claim 1.

Such an optical position sensor carried by a satellite is used to determine the position of the satellite in relation to determine another space body. · The present invention is based on

of an infrared radiation detector which . Applies to the determination of the satellite position in relation to the earth.

A conventional position sensor of the type in question can be referred to as a so-called static sensor. Its functional principle is explained with reference to FIG. Tu Figure 1 are with 1 the earth, with 2a and 2b the optical fields of view of two infrared radiation detectors of the static type for determining the roll position of a satellite, with 3ä and 3b the optical fields of view of the sensors for determining the pitch position., 'With 4 a within the field of view des- infrared radiation detector located and. from this detected edge of the earth and denoted by 5 an earth satellite.

The detector works as follows :; The infrared radiation detector has its optical axis against the earth aligned .. The detector has two pairs of optical systems, each in turn having two optical fields comprises, namely the fields of view 2a and 2b for detecting the roll position and the fields of view 3a and 3b for detecting the pitch position. These fields of view are aligned so that the edge of the earth 4 can be observed with them.

With regard to the roll position of the satellite, it applies that • those within the two fields of view 2ä and 2b of. The energies received by the earth are proportional to the areas A

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and B are on earth / which are within the assigned fields of view. The difference AW between the for the assigned fields of view received from the earth outgoing energies can be expressed by the following formula:

According to this formula, the energy difference is directly proportional to the difference in the respective fields of vision lying surfaces A and B. If the roll position of the - (O satellites changes, then the inner ones also change half of the fields of view of the earth and thus also the difference Δίί between the amounts of energy, which are detected within the fields of view 2a and 2b.

It is believed that when determining the roll of the satellite, the difference between the Amounts of energy within the two fields of view 2a and 2b can be viewed as a constant, which is represented by Δ.Wo is specified. If the satellite moves out of the assigned reference roll position, then a different one Difference: Δ WI. Is detected, the associated Angular drift «^ 0 of the roll angle, expressed as £> W1 will. The following formula applies for this:

(Awl -AwO) (2)

The change in roll angle proportional to the energy W, ie proportional to the difference between Δ W1 and A wo.

The pitch position of the satellite can also be recorded in a similar way. ,

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Accordingly, a conventional position sensor with a radiation detector is based on the simple principle that the amounts of the energies falling within the two fields of vision are compared with one another.

As explained above, the optical fields of view are initially always oriented so that the edge of the earth is observed. However, if the satellite's orbit changes, then the position sensor described cannot be operated in the predetermined manner. If accordingly the web height of the satellite is too high, both fields of view are only directed towards space. If on the other hand the orbit of the satellite is too low, then the two fields of view only hit the surface of the earth.

In both cases no edge of the earth can be observed and therefore no change in position can be detected. at a change in the orbit height in these two situations is the amount Ä, W1 given in formula 2. equal to 0. a Position sensor of the static type described is therefore not suitable for a satellite that is for different train heights is used unless the optical system is used for satellites with different orbital levels redesigned every time. For this reason, an optical position sensor of this type is suitable for use in various Railway heights not suitable.

The invention is based on the object of an optical To improve the position sensor of the type in question so that it can be used for satellites at different orbital levels can be used without the construction having to be laboriously modified ..

This job is. according to the invention by the characterizing Part of claim 1 specified features

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times solved.

In accordance with these features, appropriate optical elements, in particular mirrors, create the possibility of to vary the field of view of the optical position sensor according to the respective orbital height of the satellite. If the satellite is at a different orbit height than originally planned or for the basic type of position sensor . provided, only these optical elements need to be readjusted. be so that from the optical Position sensor at the new orbit height also the edge of the earth is detected in each case. A position sensor according to the invention can therefore easily be adapted to the respective application will.

The invention is explained in more detail in an exemplary embodiment with reference to the drawing.

Figure 2 is a schematic representation of an optical position sensor according to the invention for a Erdr Satellites at different levels;

Figure 3 is a schematic overview of the in the . Position sensors used other elements.

In Figure 2 is with 6 an optical position sensor with a Infrared radiation receiver. The radiation receiver with its optical system is denoted by 7. With 8a and 8b, in turn, the two fields of view of the position sensor of a certain orbit height above the earth 9 are designated. The edge of the earth lies within the fields of view 8a and 8b. With 12a and 12b are the fields of view of the optical position sensor marked at a different web height above the plane designated here by 10. The edge of the earth again lies within these fields of vision. 12a and 12b ..

The adjustment of the fields of view depending on the respective orbit height of the satellite is made by two Mirror TT ensures through which the respective radiation within a field of view of the .receiver 7 of the position sensor is deflected »

The functional principle of the optical position sensor is used in conjunction with. the position control around only one axis described. The position control for the other axes is similar.

The infrared radiation receiver 6 of the optical position sensor has the optical system 7 with the fields of view 8a and 8b with which the edge of the earth 9 is detected _{7 in} order to calculate the position of the satellite as described above. If, for example, the orbit height of the satellite is raised, the edges of the earth are no longer detected from a certain height.

for the second orbit height shown in the figure in relation to the earth now marked with TO. The two fields of vision of the position sensor, in this case only the space radiation would be recorded. To turn the Ef.dränder To capture, the mirrors are readjusted, so that in turn the radiation emitted by the edges of the earth into the optical system of the position sensor occurs. The fields of view of the position sensor adjusted in this way are indicated by 12a and 12.b.

FIG. 3 shows an overall diagram for the optical position sensor shown. 7 in turn denotes the optical system and 11 denotes the mirror. Furthermore is a Processor circuit 13, a motor actuator 14 for the mirrors and a stepper motor 15 are provided. When infrared energy falls from the earth in the direction of the optical position sensor, this becomes. Radiation to the mirror deflected so that it falls into the optical system- This optical system consists, for example, of an objective and an infrared receiver. Through appropriate training

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of the optical Sy stone, ζ :. Β. with the help of a so-called Chopper disk can be used to capture infrared radiation a single infrared receiver can be used from both fields of view. The incident energy is converted into a Voltage converted, which is then fed to the processor circuit 13. Γη this will be the difference between the Amounts of energy are converted into a positional error δ £ in accordance with the principle given above.

The mirror 11 can in their angular position by the Motor actuator 14 and the stepper motor 15 can be controlled in order to control the fields of view of the optical system adjust so that the edge of the earth is grasped in each case. The setting angle Δ 9 of the mirror 11 is z. B. by a Control signal transmitted from a control station on earth or by a signal residing in the satellite itself is derived depending on the change in web height.

If the stall changes its height only slightly, the mirror can be locked mechanically without using the motor actuator 14 and the stepper motor 15 will. Depending on the given orbit height of the satellite, the mirrors are fixed at a fixed angle. As mentioned above, it is also possible to readjust the mirrors continuously while the satellite is in flight,

z. B. when the satellite has a more or less powerful extrentic path, pursued. With an optical position sensor according to the invention, satellites in different Railway heights can be used without the construction of the position sensor having to be changed. It must only the setting angle of the mirror can be changed, which is dependent on the respective web height.

Claims (3)

/ ■ MESSERSCHMITT-BÖLKOW-BLOHM Ottobrunn, 08/05/83 GESELLSCHAFT BTO1 Cz / El / hl WITH LIMITED LIABILITY OTTOBRUNN · 9416 Optical position sensor for a satellite Patent claims 1. ) Optical position sensor for a satellite, which with the help of optics and 'a receiver picks up optical radiation from a spatial body, in particular the earth, within a certain directed field of view and with the help of an evaluation circuit based on the received radiation energy compared to a reference energy Positioning of the satellite determined from the viewing direction, characterized in that the optics (7) of the position sensor (6) have additional optical elements (11) for changing the viewing direction. 2. Position sensor according to claim 1, characterized in that the additional optical elements adjustable mirrors (11) are. 3. Position sensor according to claim 2, characterized in that with the mirrors (11) an adjustment ■ motor (15) is connected.