# Method of controlling complementary filters in satellite navigation system

FIELD: physics.

SUBSTANCE: navigation system calculates positions which are corrected using complementary filters, each of which excludes data coming from one of the satellites when a fault is detected in one of the satellites. The complementary filter which excludes this satellite becomes the main filter and the other complementary filters are initiated by the new main filter.

5 cl, 2 dwg

The technical field to which the invention relates.

The invention relates to a method of controlling surge in a satellite-based navigation and localization, such as a GPS (“Global Positioning System”), which is equipped with a vehicle and, in particular, the aircraft.

The level of technology

Such a navigation system during aircraft flight allows to calculate the sequential position of the aircraft using the main filter combining data coming from a group of satellites visible above the horizon of the aircraft, and, if necessary, data from the inertial counter current coordinates or similar devices installed on Board the aircraft. It should be recalled that the horizon is the line that separates what is in front of the plane is hidden by the curvature of the Earth and what remains hidden. When using a GPS system above the horizon of the aircraft there is a certain maximum number of satellites (i.e. the maximum number of satellites that were not hidden by the curvature of the Earth relative to the aircraft), the order of ten, however, it often happens that the terrain or part of the aircraft hides one or more of these satellites. However, this navigation system is working, if it has data, at least four satellites, which form the visible satellites. This navigation system is relatively accurate, if the satellites are working correctly, but its effectiveness is sharply reduced, as only one of the satellites fails, affecting the reliability of transmitted data.

To solve the problem, the navigation system calculates the position adjusted by using additional filters, each of which excludes data from one of the satellites. When it detects the failure of one of the satellites, additional filter excluding this satellite, becomes the main filter, and initializing other additional filters comes from the new main filter.

The invention

In this regard, it is desirable to have a means to facilitate the management of additional filters.

For this purpose, according to the invention, proposes a method of managing additional filters in the navigation system, which is equipped with a vehicle and which during transit of the vehicle generates at least one position of the vehicle using the main filter combining data from the visible group of satellites that are present above the horizon of the vehicle, with each additional filters to exclude data from one of the satellites, to obtain the adjusted position in the event of the failure of the excluded satellite. The method comprises the following steps:

on the basis of the position of the vehicle determine theoretical group of satellites that are present above the horizon,

- for any satellite, there is in his theoretical group, create and maintain additional filter excluding the satellite.

Thus, additional filters are saved until eliminated their satellites are present in theoretical group, regardless of whether these satellites are hidden or visible. Since theoretical group undergoes relatively little change in the travel time of the vehicle, there is relatively little creatures and erase additional filters.

Preferably, for any satellite that is present in theoretical group, the method comprises a step of enabling the satellite to the existing additional filters since the advent of the satellite in theoretical group.

Thus, satellite, appearing in theoretical group include existing additional filters, without waiting for detection of the satellite main filter. Therefore, this inclusion can be carried out with the load distribution calculations.

Preferably, the position used to determine theoretical groups receive from the main filter.

In this case, certain theoretical group exactly matches the vehicle position on the route, even if the destination or points of passage of the vehicle has changed during the PU and repetition.

Preferably, when the satellite disappears from theoretical group at any point of the path, the method includes a step of waiting a predetermined period of time before you can remove the additional filter excluding the satellite.

It is of particular interest in the case of temporary disappearance of the satellite from theoretical group.

Preferably, disappeared when the satellite appears in theoretical group, the method includes a step of waiting convergence of filters before creating an additional filter excluding this satellite, and re-enable the satellite to the existing additional filters.

This avoids re-enable additional filters companion, who has not detected a fault in the time of his disappearance from the group and may distort adjusted position.

Other features of the invention will be more apparent from the following description of non-restrictive private option of carrying out the invention.

Brief description of drawings

This description is presented with reference to the accompanying drawings, on which:

figure 1 - schematic view in perspective of a group of satellites that are present above the horizon of the aircraft;

figure 2 - schematic view of the on-Board navigation system of the aircraft.

Detailed description of the invention

As is evident from the drawings, the method in accordance with the present invention described in this case in connection with the application for the aircraft 1, containing on-Board navigation system 10 that uses the data coming from the satellites 2, 3, 4, 5 and 6, rotating in orbit around the Earth 100, and data received from the onboard inertial counter 7 current coordinates of the aircraft 1.

Inertial counter 7 current coordinates in itself known on the basis of readings of sensors mounted on an aircraft 1, issue-specific data, in particular, to the position of the aircraft 1 in the air, its speed, and so on

The satellites 2, 3, 4, 5, 6 are part of a whole satellites in geostationary orbit around the Earth and belonging to a satellite localization system like GPS. Each satellite continuously emits a signal that contains information about its location and the time of radiation of the signal. Of course, the invention can also be applied to other satellite localization systems, such as GALILEO, when she stepped into the building.

The navigation system 10 includes a block 11 calculations connected with the inertial counter 7 and the receiver 8 of the signals coming from the satellites. As is known, the calculation block 11 contains processors and remember what their device which enable it to calculate pseudoresistance separating aircraft 1 from each satellite, a signal which is captured by the receiver 8, and concatenate these pseudoresistance and data received from the inertial counter 7 to determine, inter alia, the position of the aircraft 1.

As is well known, the Association carried out using the main filter R, which takes into account data obtained from the satellites that are present above the horizon of the aircraft 1 and which are visible in the sense that their emitted signals are received by the receiver 8. In this case, these satellites are satellites 2, 4, 5, 6, forming the visible satellites and the satellite 3 in this case, the hidden mountain.

Unit 11 calculation also uses additional filters a, b, C, D, E, each of which excludes the satellite to obtain the adjusted position when the excluded satellite is identified as faulty. In this case, an additional filter excluding this satellite replaces the main filter, and other filters are initialized from the new main filter. Manage filters is provided by the calculation block 11, which contains a computer program for the control of filters and description which follows.

The main filter R s the et system satellites as as the receiver 8 receives data from them. In this case, the main filter R includes the satellites 2, 4, 5, 6. If one of these satellites in the future is hidden, this companion is just not available, but it is not erased from the main filter R.

To create additional filters a, b, C, D, E unit 11 calculation determines theoretical group of satellites that are present above the horizon of the aircraft, on the basis of the provisions of this aircraft received from the main filter. This definition in itself is relatively easy, because the position of the satellites is known. For example, suppose that the first definition of theoretical group shows that the satellites 2, 4, 5, 6 are above the horizon. The computing unit generates four additional filter a, b, C, D, each of which eliminates one of the satellites 2, 4, 5, 6. Additional filter And includes the satellites 2, 4, 5; additional filter includes satellites 2, 4, 6; additional filter includes satellites 2, 5, 6; additional filter D includes the satellites 4, 5, 6, and, thus, each additional filter is based on the data received from all satellites, except for one.

Further theoretical definition of the group shows that the satellite 3, though hidden aircraft 1, is above the horizon. In this case, the unit 1 calculation creates an additional filter, excluding the satellite 3 and including satellites 2, 4, 5, 6, and updates the additional filters a, b, C, D, including the satellite 3. In this case, an additional filter And includes the satellites 2, 3, 4, 5; additional filter includes satellites 2, 3, 4, 6; additional filter includes satellites 2, 3, 5, 6; additional filter D includes the satellites 3, 4, 5, 6. While Sputnik 3 remains hidden, the main filter P includes only the satellites 2,4, 5, 6.

If at some time of the flight, the satellite disappears from theoretical group, the method includes a step of waiting a predetermined period of time before removing the additional filter excluding this satellite. This satellite is not erased from additional filters. At the end of the waiting period, the memory space occupied by this satellite for additional filters will be released. Thus, avoid re-creating an additional filter, if the disappearance of the satellite is only temporary.

Upon completion of the waiting period, if the satellite appears in theoretical group, the method includes a step of waiting convergence of filters before creating an additional filter excluding this satellite, and re-enable the satellite to the existing additional filters.

Of course, the invention is not limited to the described variant execution and covers uboy option not beyond the scope of the invention defined by the attached claims.

In particular, can be carried out, including a new satellite in the existing additional filters when it is detected by the receiver 8. However, this assumes a higher load calculations than in the described embodiment.

In addition, a theoretical group can be defined in advance for the access points of the vehicle during transit, if it is known in advance and if there is confidence that the vehicle will actually follow this path.

Periods of waiting, mentioned in the described embodiment, are optional.

1. The way to control additional filters (a, b, C, D, E) in the navigation system (10), which is equipped with the vehicle (1) and which receives data from a system of satellites, while the navigation system during transit of the vehicle generates at least one position of the vehicle using the main filter (B) combining the data coming from the visible group of satellites (2, 4, 5, 6) of the specified system present on the horizon of the vehicle, with each additional filters to exclude data from one of the satellites, to obtain adjusted is the provisions in the event of the failure of the excluded satellite, characterized in that it contains the following stages:
on the basis of the position of the vehicle determine theoretical group of satellites(2, 3, 4, 5, 6) this system present above the horizon relative position of the vehicle,
for any satellite that is present in theoretical group, create and maintain additional filter excluding the satellite.

2. The method according to claim 1, containing for any satellite that is present in theoretical group(2, 3, 4, 5, 6), the step of enabling the satellite to the existing additional filters (a, b, C, D, E) since the advent of the satellite in theoretical group.

3. The method according to claim 1, in which the position used to determine theoretical group(2, 3,4, 5, 6), receive from the main filter (R).

4. The method according to claim 1, wherein, when the satellite disappears from theoretical group(2, 3, 4, 5, 6) in any point of the path, the method includes a step of waiting a predetermined period of time before you can remove the additional filter (a, b, C, D, E), excluding the satellite.

5. The method according to claim 4, in which, disappeared when the satellite appears in theoretical group(2, 3, 4, 5, 6), the method includes a step of waiting convergence of filters (a, b, C, D, E), before you can create an additional filter (a, b, C, D, E), excluding the satellite, and again to enable this companion who is concerned more filters.

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1 dwg

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