Method to determine the orientation of the azimuth direction of a navigation apparatus

The invention relates to a method for determining the orientation of a defined azimuthal main direction of a navigation device located in a closed or open space, which receives radiation in the space emitted by electromagnetic waves or ultrasound waves and evaluates them in this regard.

Various methods and systems for finding directions are known from radio navigation technology, in particular for aviation.

For example, from Brockhaus: "Naturwissenschaften und Technik", (special edition), volume 1, A-Ek, 1989, ISBN 3-7653-0451-4, Mannheim, page 23 (keyword: ADF) and volume 2, El-In , ISBN 3-7653-0452-2, page 160 (keyword: radio direction finder) known radio direction finding method (ADF; Automatic Detection Finding) a high-frequency carrier oscillation is emitted by a ground station as a so-called radio beacon. This can be unmodulated or contain an identifier for the beacon. An on-board receiver determines its orientation using a so-called cross antenna. The angle between a defined main axis of the antenna and the incoming beam is determined. The disadvantage of this method is that the on-board receiver can determine in which azimuthal direction the emitting ground station is, but it is not made known to him from the direction finding result in which direction the north is. Similar bearing methods are also from R. Grabau, K. Pfaff: "Funkpeiltechnik", 1989, Franckh'sche Verlaghandlung, W. Keller & Co., Stuttgart, ISBN 3-440-05991-X, pages 97 to 99 and pages 344 to 347.

In the case of the radio beacon process (VOR; VHF Omnidirectional Radio Range), which is also mainly used in aviation, for example in Brockhaus: "Naturwissenschaften und Technik", (Special Edition), Volume 5, So-Z, 1989, ISBN 3-7653-0455-7, Mannheim, page 220 (keyword: VOR), a VOR transmitter emits its radiation on two frequencies. On the one hand it sends a short signal in all directions all around (omnidirectional) and then on the other frequency it emits a signal with a directed beam in a north direction, which rotates slowly clockwise. An on-board receiver placed on this system can now measure the time that elapses from the reception of the omnidirectionally transmitted signal to the reception of the directionally transmitted signal. From this time period and the rotational speed, the space sector in which the on-board receiver is currently located can be determined in the on-board receiver. However, there is the disadvantage that the on-board receiver learns nothing about its own orientation in space. The north direction must be determined by himself.

The VOR method and the ADF method both have the disadvantage that they are methods in analog technology from aviation. Accordingly, they work poorly under indoor conditions, since reflections of the transmitter radiation on the walls have bad effects on the necessarily narrow-band signals. The use of these known methods in indoor areas is therefore very critical. These two methods also have in common that they are not suitable for determining the north direction. However, since they are used in aviation, where a magnetic or gyro compass is common, this is not a serious problem. These beacons are used as "flyover points" on airways, so that it is usually sufficient to know the course of the beacon.

DE 35 26 564 A1 describes a method for determining the current location of container vehicles within a storage area. In this method, two stationary transmitters are used, each of which emits bundled wave energy in the form of a transmission beam continuously sweeping over the storage area. Each of the two transmission beams is embossed with direction information which characterizes its current direction of radiation. In each container vehicle, the two transmission beams are received by means of a receiver accommodated therein, and the direction information contained in the two received transmission beams is determined, so that the position line and the current position of the container vehicle in question can be calculated from these two direction information items using a position calculator. It is of essential importance here that two separate, spaced-apart transmission stations must be provided and that an intersection point calculation analogous to the principle of cross bearing is used to determine the vehicle position. The determination of the cardinal directional orientation of a defined azimuthal main direction of the vehicle, container or a navigation device possibly contained therein, that is to say a compass function, is by no means possible with this known method and is therefore not sought.

The GPS (Global Positioning System) compass is also known as a navigation device. Here, a receiver determines the location of at least two antennas, which are mounted at a fixed distance from each other. He can therefore find the north direction. A disadvantage of this is that at least four satellites must be visible. This is not possible for indoor use. Therefore, at least four pseudo radiation sources would have to be installed in the room, which causes considerable effort and considerable associated costs. GPS compass receivers are described, for example, in EP 0 587 954 A1, US-A-4 384 293 and US-A-4 881 080.

The object of the invention is to provide a direction detection method which enables a navigation device receiving the electromagnetic radiation or ultrasound radiation of a transmission station in a closed or open space, not only the angular position with respect to this transmission station, but also to a defined geographical direction, preferably the north direction. This is particularly to ensure that a person carrying the navigation device in a room within a building can always reliably recognize the azimuth-directional position of the navigation device in the room via the local position communicated to it by the transmitting station, the navigation device using a mobile device used as part of a travel planning system wireless information device can be.

According to the invention, which relates to a method of the type mentioned, this object is achieved in that, on the one hand, an omnidirectional radiation is emitted by a transmitting station, which is emitted by a direction finding device of the receiving navigation device for determining the angle δ between the main direction and the Direction to the transmitting station is used so that a directional radiation is emitted from the same transmitting station to the other in the azimuth plane, which contains the start of a function indicating its current orbital angle position in a defined geographical direction and is used in the receiving navigation device by evaluating this function to determine the angle α at which the distance between the location of the receiving navigation device and the transmitting station is relative to the fixed geographical direction, and that by combining the two angles δ and α using the mathematical relationship<maths id="math0001" num=""><math display="block"><mrow><mtext>γ = α + δ - 180 °</mtext></mrow></math><img file="EP1102084A2_D0001.tif" /></maths> it is determined at what angle γ the defined main direction of the receiving navigation device is relative to the defined geographical direction. The defined geographical direction in which the function of the directional radiation of the transmitting station begins is preferably the north direction.

The signals emitted omnidirectionally by the transmitting station are advantageously imprinted with data signals which can be used to determine the position in the receiving navigation device (so-called beacon function).

The receiving navigation device can expediently be a mobile wireless information device used in the context of a travel planning system, which is carried by a person, is used for planning and the process of a trip and, for this purpose, records and processes position data, in addition to those in the room, the bearing serving transmitting stations can also come from other position determining devices that provide a navigation service.

When using such travel planning systems, the method according to the invention enables a directional instruction to be output to a person by the wireless information device, since not only its position but also its azimuthal orientation in space is then known. Directional instructions such as "go right" are then possible to reach a local destination.

The further position detection devices mentioned can be beacons that are operated with the computer operating program “Jini®” and / or beacons that are accommodated in lamps. Such beacons then work in combination in determining the position of the information device in the context of a travel planning system with the transmitting stations also used for direction finding.

If electromagnetic waves are used in the method according to the invention, high-frequency radio waves, in particular in the frequency range of the centimeter waves, and waves in the infrared range are considered.

A first form of implementation of the method according to the invention is that a CDMA (Code Division Multiple Access; code division multiplex) code word is periodically emitted by the transmitting station through the omnidirectional radiation. In this case, data can also be impressed on the CDMA code word, which are used in particular to determine the position in the receiving navigation device (beacon function).

In this form of implementation, a second CDMA code word is emitted simultaneously by the directional radiation, the beginning of the two CDMA code words always being time-synchronous.

The directional radiation is carried out in such a way that the beam always points towards the beginning of the code word in the direction of the defined geographical direction, i.e. preferably in the north, and rotates once through 360 degrees until the next beginning of the code word, as a result of which the function for determining the angle that specifies the current circumferential angle position α is formed. The second CDMA code word emitted by the directional radiation is advantageous orthogonal to the CDMA code word emitted periodically by the omnidirectional radiation. The receiving navigation device, which has previously synchronized the carrier of the omnidirectional radiation, despreads the CDMA signal contained in the directional radiation by correlation and thus determines the angle α, at which the distance between the location of the receiving navigation device and the transmitting station is related on the defined geographical direction, that is, preferably the north direction.

Instead of the transmission with CDMA code words, a transmission with FDMA (Frequency Division Multiple Access; frequency division multiplex), TDMA (Time Division Multiple Access; time division multiplex), SDMA (Space Division Multiple Access; space division multiplex) or combinations thereof can also be carried out.

In order to determine the position of the receiving navigation device, a cross bearing with two transmitting stations can advantageously be carried out.

When using radio waves, the angle δ between the main direction of the receiving navigation device and the direction to the transmitting station can advantageously be determined by means of a cross antenna or an intelligent antenna. When radio waves are used, the directional radiation is expediently formed in the transmitting station by means of a rotatable directional antenna or a so-called smart antenna.

A second embodiment of a method according to the invention is designed such that the infrared radiation from the transmitting station is emitted by means of luminescent diodes, ie LEDs, which are active in the infrared range and emit in different spatial directions. The luminescent diodes effective in the infrared range can send different CDMA code words to simplify the direction determination in the individual spatial directions. The infrared radiation coming from the transmitting station is advantageously received via a dome which is attached to the receiving navigation device and is permeable to infrared radiation and which images the upper hemisphere in one plane, the direction of incidence of the infrared radiation coming from the transmitting station then being determined by means of a dome segmented sensitive semiconductor field is determined, which is located under the permeable dome.

The invention is explained below with reference to the accompanying drawings. Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>1 shows a diagram to illustrate the bearing of the north direction that can be carried out with the aid of the method according to the invention,</dd><dt>Fig. 2</dt><dd>1 shows a schematic side view of a device for carrying out the method according to the invention which works with infrared direction finding,</dd><dt>Fig. 3</dt><dd>a schematic view of the device of Figure 2 from above, and</dd><dt>Fig. 4</dt><dd>is a schematic side view of a transparent to infrared radiation, used in the device of Figures 2 and 3 dome for receiving either LEDs or detectors.</dd></dl>

The principle of the method for radio waves is described with reference to FIG. A transmitting station S in a room within a building periodically radiates omnidirectionally a CDMA code word, which can also be imprinted with data to fulfill a beacon function for position determination purposes. The radiation is advantageously carried out with a high carrier frequency, for example at 20 GHz, so that the signals are damped as quickly as possible by the air absorption. Likewise, such waves cannot usually penetrate the walls of a room. A receiving navigation device E can determine the angle δ with the aid of a cross antenna or an intelligent antenna. In the navigation device E, the angle δ is the angle between a defined main direction H of this navigation device E and the direction R of the route to the transmitting station S.

The receiving navigation device E can be a mobile wireless information device used in the context of a travel planning system, which is carried by a person, is used for planning and the process of a trip and, for this purpose, records and processes position data, which is provided by the transmitting stations located in the room and used for bearing can also come from other position determination devices that provide a navigation service.

Simultaneously with the CDMA code word mentioned, the transmitting station S emits a second code word, which is as orthogonal as possible, with a directional antenna in a manner similar to that of the VOR rotary beacon. The beginning of the two code words is always synchronous. This directional radiation from the transmitting station S occurs in that the beam always points north at the beginning of the code word. It rotates once through 360 degrees until the next code word begins. This directional beam rotation can be realized with a rotatable directional antenna or a so-called smart antenna.

The receiving navigation device E, which has already synchronized the omnidirectional carrier, can spread the directed beam by correlation and thus determine which space segment it is in. The navigation device E thus determines the angle α that exists between the north direction N and the direction R of the route connecting the navigation device E and the transmitting station S. A combination of the angles δ and α can be used in the navigation device E to determine the angle γ at which the main direction H of the navigation device E to the north direction N is held by a person at the moment. In this way, a real compass function is implemented in the navigation device E, apart from the possibility of determining the position. The mathematical connection is as follows:<maths id="math0002" num=""><math display="block"><mrow><mtext>γ = α + δ - 180 °.</mtext></mrow></math><img file="EP1102084A2_D0002.tif" /></maths>

In the implementation form explained below with reference to FIGS. 2 to 4, radio waves are not used, but infrared emitters. The principle of operation is, however, in principle similar to the implementation method previously described with reference to FIG. 1 using radio waves.

The transmitter station S attached, for example, to the ceiling D of a room here preferably consists of luminescent diodes L designed for emitting infrared radiation, which are also known as “LEDs” and which radiate in different spatial directions. Such a design in transmission segments A, which are accommodated under a dome K that is transparent to infrared radiation, is particularly advantageous since such a transmission station S is extremely inexpensive and easy to implement. Designs are also possible in which the luminescence diodes send different code words in the individual spatial directions and thus simplify the direction determination by a navigation device E receiving the infrared radiation.

Mounted on the mobile receiving navigation device E is a dome K which is transparent to infrared radiation and which images the upper hemisphere in one plane. Under this dome there is a semiconductor sensitive to infrared radiation, which is divided all around into receiving segments B with infrared detectors and can thus determine the direction of incidence. Spreading the signal by means of CDMA code words also results in good usability in the indoor area and good suppression of the background radiation.

4 shows a dome K which is transparent to infrared radiation and which can either be used for the transmitting station S and then includes infrared luminescent diodes L arranged in transmitting segments A or which can be used in an externally identical form for the receiving navigation device E. and in this case encloses infrared detectors F made of semiconductor material arranged in receiving segments B. The lines drawn in dashed lines correspond to transmission segments A and reception segments B.

Reference list

<dl id="dl0002" compact="compact"><dt>A</dt><dd>Broadcast segments</dd><dt>B</dt><dd>Reception segments</dd><dt>D</dt><dd>ceiling</dd><dt>E</dt><dd>Receiving navigation device</dd><dt>F</dt><dd>Infrared detector</dd><dt>H</dt><dd>Main direction of navigation equipment</dd><dt>K</dt><dd>dome</dd><dt>L</dt><dd>Luminescent diodes (LEDs)</dd><dt>N</dt><dd>North direction</dd><dt>R</dt><dd>Direction to the transmitting station</dd><dt>S</dt><dd>Transmitter station</dd><dt>α, δ, γ</dt><dd>angle</dd></dl>