DE102020206032A1 - Method for determining a position of a mobile device within a building and mobile device, location device and system for carrying out the method - Google Patents

Abstract

The invention relates to a method for determining a position of a mobile device (2) within a building, the mobile device (2) having a clock (23) and a magnetometer (21), comprising the transmission of a radio signal that carries time information; Receiving a first position information determined from the radio signal; Receiving information on a magnetic map of the building; Measuring a magnetic field at the position of the mobile device (2) by means of the magnetometer (21); Determining a second position specification from the measured magnetic field and the magnetic mapping of the building; Determining a corrected position specification from the first position specification and the second position specification. The invention also relates to a mobile device, a locating device and a system.

Description

The present invention relates to a method for determining a position of a mobile device within a building as well as a mobile device, a locating device and a system for carrying it out.

State of the art

Buildings in developed countries can be large and easily lost. In addition, people spend more and more time indoors, so that there is a need for solutions for indoor navigation and location.

While the possibilities of outdoor navigation have found their way into almost every mobile and smart device, solutions for the indoor area can be expanded further. No technology has yet been able to establish itself across the board in the indoor area. For example, the position of a receiver cannot be determined with sufficient accuracy for some applications using the existing WiFi infrastructure.

In the US 2014/148196 A1 discloses a method for determining the position of a mobile device in an indoor area, in which two different types of position determination are used. The first type can be traced back to the WiFi infrastructure already mentioned. Messages are exchanged via “wireless tags”, the distance information of which is known and which are arranged within an interior space, which enables a user's position to be determined with regard to a subset of the “wireless tags”. As already explained above, the accuracy of such a position determination is limited. The second type is that the "wireless tags" send a signal that is measured by fixed "beacons" and evaluated with regard to signal strength in order to determine the position. This type of position determination is also limited in terms of accuracy.

US 2018/027386 A1 discloses that a mobile device detects other physical measured variables in addition to the WiFi signal, such as a magnetic field, but does not provide a solution in order to thereby significantly increase the accuracy of the measurement.

EP 3 330 891 A1 discloses a 4G or 5G communication system in which the transmission of magnetic fields from a mobile device, the transmission of the transmitted signal strength and the measurement of magnetic fields are used to determine the position.

Disclosure of the invention

According to the invention, methods for determining a position of a mobile device within a building as well as a mobile device, a locating device and a system for carrying it out are proposed with the features of the independent claims. Advantageous refinements are the subject matter of the subclaims and the description below.

According to one aspect of the invention, it is proposed to determine a position of a mobile device within a building both by transmitting a radio signal to enable a transit time measurement and by determining a position information from a measured magnetic field and a magnetic mapping and to use these two position information to provide a corrected position information determine. This is carried out in particular by the mobile device, so that self-location takes place.

In this way, a very precise, in particular centimeter-precise, position determination within a building is possible. The accuracy compared to the prior art can be improved many times over. Inaccuracies in determining the position from the magnetic field measurement due to magnetic materials in the room can be corrected by determining the position from the radio signal. Conversely, inaccuracies in determining the position from the radio signal due to wall reflections can be corrected by determining the position from the magnetic field measurement.

The first position information and / or the information about the magnetic mapping are preferably called up and received from a network to which the mobile device is wirelessly connected. In particular, it can be a WiFi connection or a cellular connection. The source of the first position indication and the information about the magnetic mapping can be the same source. However, they can also be different sources. This is advantageous because network connections are usually available anyway.

The corrected position information is expediently determined by forming a weighted mean value from the first and second position information. The two weights with which the first and the second position information are weighted and whose sum expediently results in 1.0 can be determined from an inaccuracy of the respective position information. The higher the inaccuracy, the lower the weight is set for this position specification. The inaccuracy can can be determined by determining the position redundantly, ie with more measurements than necessary (with three coordinates, for example, at least four measurements), and evaluating how the position determination changes if only the minimal systems (ie as many measurements as necessary) are used Position determination are evaluated. If the position information changes only a little, then the error due to reflections on the wall or distortion of the magnetic mapping is small.

According to a second aspect of the invention, a mobile device is proposed which has a clock and a magnetometer and is set up to carry out a method according to the invention. This mobile device is advantageously able to determine its own position very precisely.

In an advantageous embodiment, the clock is designed as an atomic clock. In particular, the clock is designed as an atomic clock with rubidium, or abbreviated Rb, atoms and is set up to use the hyperfine transition of the Rb atoms as a frequency standard. This is advantageous because with such a clock a very precise time determination is possible in the smallest of spaces.

The magnetometer of the mobile device expediently has a crystal body with color centers. This is advantageous because it enables very precise magnetic field measurements.

Color centers such as nitrogen vacancy centers in a crystal body, in particular in a diamond or diamond lattice, also referred to as NV centers (NV stands for “Nitrogen Vacancy”), can be used to measure magnetic fields. By exciting such NV centers with light, in particular green light, and microwave radiation, a magnetic field-dependent fluorescence of the same can be observed. Other examples of such color centers are defect centers in SiC or SiV in diamond. The NV centers have the specific advantages of ultra-high sensitivity (sometimes <1 pT / √Hz), vector magnetometry (i.e. determining the direction of the magnetic field), a high measuring range (> 1 T), linearity (via the Zeeman effect) and that Absence of degradation, since the measurement is based on quantum mechanical states (similar to the hydrogen atom, in which the Rydberg constant is a fixed energy that is a constant that is independent of location and time for all atoms).

In order to read a sensor based on NV centers, the magnetic resonance of the triplet of the ground state can be detected optically (ODMR, optically detected magnetic resonance). For this purpose, the NV center can be stimulated with a green light. The red-shifted fluorescent light shows a characteristic dip in the energetic position of the electron spin resonance. Due to the Zeeman effect, the position is linearly dependent on the magnetic field. This enables a highly sensitive magnetic field sensor to be constructed.

Preferably the magnetometer is an optically pumped magnetometer. This is advantageous because optically pumped magnetometers allow precise magnetic field measurements in a small space.

A typical optically pumped magnetometer has a cell in which two different alkali metal gases are provided. Furthermore, a pump light source is provided which is set up to radiate circularly polarized pump light with a first wavelength into the cell in order to polarize the spins of the first alkali metal. The spins of both alkali metals interact with each other. A measuring light source is set up to radiate linearly polarized light into the cell, which has a wavelength that differs from the first wavelength and is set up to change its polarization direction depending on the spin polarization of the second alkali metal gas. In this way, if, for example, the direction of the pump light and the measurement light coincide, a static magnetic field can be measured perpendicular to the direction of the two light beams. By applying a bias magnetic field in the direction of the light beam, it is also possible in this way to determine an alternating magnetic field perpendicular to the direction of the light beam. Since an atomic clock also has a cell with gaseous alkali metal atoms, synergies can be used in the construction and operation of the magnetometer and clock with an optically pumped magnetometer.

The mobile device expediently also has one or more artificial neural networks which are trained to calculate an optimal corrected position information from deviations between the first position information and the second position information. This is advantageous since the correlation between the corrections can be relatively complex. Artificial neural networks can automatically recognize patterns based on real correction values and in this way calculate the best possible corrected position information. For the training of the neural network, the wearer of the mobile device is requested, e.g. when entering the room, to visit a few reference points or to set up the mobile device there. When entering the room again, the system recognizes that training data is already available for this, so that no new training is necessary, but the neural network parameterized for this room can be used directly.

According to a further aspect of the invention, a so-called head-mounted display (HMD), that is to say a visual output device to be worn on the head, with a mobile device according to the invention is proposed. Typical representatives of HMDs are video and data glasses, such as so-called virtual or augmented reality glasses. The invention can be used advantageously for determining the position of HMDs in a building. In particular when an HMD is connected to a brain-machine interface, the invention is particularly advantageous since brain-machine interfaces are usually already equipped with magnetic field sensors that are provided for measuring brain activities. These can then also be used to determine your position. A position determination by means of a radio signal can thus be advantageously combined with a position determination by means of magnetic field measurement. HMDs can also already be equipped with magnetic field sensors (for example so-called proximity sensors) in order to detect magnetic warning fields in the vicinity of walls, for example.

According to a further aspect of the invention, it is proposed to determine a position of a mobile device within a building by receiving a radio signal from at least three radio signal receivers, determining a first position of a transmitter of the radio wave and transmitting the determined first position, with magnetic fields also being transmitted are generated by at least three magnetic field generators in such a way that a point within the room can be clearly assigned to each magnetic field or certain measured values of the resulting magnetic field generated by the superposition of the magnetic fields of the three magnetic field generators can be assigned to each point in the room, and information about the magnetic mapping of the room is provided. In this way, the same advantages can be achieved as in the method according to the invention according to the first aspect.

The first position determined and / or the information about the magnetic mapping are preferably sent via a network to which the mobile device whose position is to be determined is connected. This is advantageous because in this way no separate data transmission method needs to be set up.

According to a further aspect of the invention, a locating device is proposed which has at least three radio signal receivers with clocks and at least three magnetic field generators, the clocks of the receivers being synchronized with one another, which is also set up to carry out a method according to the third aspect. This locating device is advantageously able to determine a position of a mobile device within a room with centimeter accuracy.

In an advantageous embodiment, the clocks are designed as atomic clocks, in particular as atomic clocks with Rb atoms, which are set up to use the hyperfine transition of the Rb atoms as a frequency standard. This is advantageous because in this way very exact time measurements can be guaranteed in a small space.

According to a further aspect of the invention, a system is proposed which is composed of a location device according to the fourth aspect and a mobile device according to the second aspect. This system enables a very precise position determination of the mobile device within a building through an interaction between the location device and the mobile device.

The clocks of the radio signal receivers and the clock of the mobile device are expediently synchronized with one another. In this way, the accuracy of the position determination can be further improved.

Further advantages and embodiments of the invention emerge from the description and the accompanying drawing.

The invention is shown schematically in the drawings using an exemplary embodiment and is described below with reference to the drawings.

Figure list

• 1 shows a system for determining a position of a mobile device within a building according to a preferred embodiment of the invention in a schematic representation;
• 2 shows a flowchart for a preferred embodiment of a method according to the invention.

Embodiment (s) of the invention

In 1 A preferred embodiment of a system for determining a position of a mobile device within a building is shown and designated by 100. The system 100 is arranged, for example, in a room of a building, the wall of which is denoted by 1.

The system 100 has a mobile device 2 on. The mobile device 2 For example, it can be a smartphone whose position in space needs to be determined with a precision of a few centimeters. It has a clock 23 and a magnetometer 21 . Both the clock 23 and the magnetometer are preferably miniaturized and each have a volume of a few mm ³ . The mobile device 2 still has a radio transmitter 22nd on. It is set up to send out a radio signal, for example in the GHz range.

The system 100 furthermore has a locating device. In this embodiment, the locating device has three radio signal receivers 12A , 12B , 12C with clocks 11A , 11B , 11C and three magnetic field generators 13A , 13B , 13C on. In this embodiment the clocks are 11A , 11B , 11C the recipient with the watch 23 of the mobile device.

That from the mobile device 2 The transmitted radio signal travels at (essentially) the speed of light to the three radio signal receivers 12A , 12B , 12C the end. The one with the clock 23 in the mobile device 2 synchronized clocks of the radio signal receivers 11A , 11B , 11C are set up to measure the transit time of the signal, from which the distance between the mobile device and the respective radio signal receiver is determined 12A , 12B , 12C can be calculated. This means that, in principle, a navigation accuracy of a few centimeters can be achieved. This calculated first position information is then preferably sent to the mobile device via a network, for example WiFi or cellular radio 2 sent.

Due to possible reflections on the walls 1 or objects in the room can lead to incorrect positioning. This is why the so-called TOF navigation system (“time of flight”) is supplemented by a magnetic position determination.

Therefore, the location device has several stationary points around space that corresponds to the location of the stationary radio signal receiver 12A , 12B , 12C can match, one magnetic field generator each 13A , 13B , 13C on. These are set up to generate magnetic fields. The superposition of the fields is chosen so that a clear magnetic mapping of the room is achieved, ie that the position within the room or building can be determined on the basis of the magnetic field prevailing at the position. By precisely measuring the magnitude and direction of the magnetic field at the location of the mobile device 2 by means of the magnetometer 21 In principle, position determination is also possible with centimeter accuracy. Magnetic materials in the room that change their location can, however, lead to incorrect results when determining the position, so that the TOF triangulation can be used as a correction and vice versa.

A flowchart showing the position determination process is shown in FIG 2 shown.

With S101 the TOF position determination is called. With S102 is called the magnetic position determination. In one step S103 the first position information from the TOF position determination and the second position information from the magnetic position determination are related to one another and an error correction is determined. This can, for example, have been learned in advance by means of an artificial neural network and then be determined according to this method.

A higher accuracy of the measurement is achieved, for example, by using redundant systems, i.e. with three coordinates x, y, z by using four or more radio signal receivers or magnetic field generators. The redundancy helps to make the system less susceptible to failure and at the same time increases the accuracy of the position determination.

Let system A be the system that determines the position by measuring the transit time, and system B the system that determines the position by means of a magnetic card.

To the position of the mobile device 2 In space, ie to determine the coordinates x, y and z with system A, at least three transit time measurements are necessary. When the mobile device 2 For example, if a radio pulse is isotropically emitted into the room, at least 3 receivers are required at different points in the room in order to determine the position.

If there are more than three, the system is redundant and the redundancy helps to make the system less susceptible to failure and at the same time increases the accuracy of the position determination. If one only analyzes for both systems how the accuracy changes when a redundant system, but only the minimum necessary, is used, one can infer which system has greater inaccuracy in determining the position. It is the system in which the discrepancy between the minimum system and the redundancy system is greater. The position information can then be weighted according to the accuracy so that minimal systems can also be used during operation.

In step S104 the corrected result is then output. This is particularly advantageous since the correction relationships are often very complex. The patterns of the relationships can be recorded automatically by means of the artificial neural networks.

As explained, is the number of radio signal receivers 12A , 12B , 12C not limited to three. The number of magnetic field generators 13A , 13B , 13C just as little. The generation of the magnetic field can be generated both by permanent magnets and by current-carrying coils, in the latter case both constant currents and alternating currents of different frequencies can be used.

erfasst werden. Alternativ kann zur Messung des Magnetfeldes auch ein optisch gepumptes Magnetometer verwendet werden. Solche Magnetometer sind in US 9 946 609 beschrieben.The clock 23 in the mobile device as well as the clocks 11A , 12A , 13A in the receivers of radio signals 11B , 12B , 13B are preferably atomic clocks with a chip size of less than 2 mm. Such watches are in U.S. 8,624,682 A described. For the magnetometer 13A , 13B , 13C the optically detected magnetic resonance of NV centers in diamond is preferably used (ODMR), which is shown in U.S. 9,851,418 A is described. Thus, magnetic fields with a resolution of up to $1\text{pT /}\sqrt{Hz}$

are recorded. Alternatively, an optically pumped magnetometer can be used to measure the magnetic field. Such magnetometers are in U.S. 9,946,609 described.

The miniaturized atomic clock in the mobile device can be used as a frequency standard for an ODMR measurement to detect the magnetic field.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2014148196 A1 [0004]
• US 2018027386 A1 [0005]
• EP 3330891 A1 [0006]
• US 8624682 A [0043]
• US 9851418 A [0043]
• US 9946609 [0043]

Claims (15)

A method for determining a position of a mobile device (2) within a building, the mobile device (2) having a clock (23) and a magnetometer (21), comprising the steps of: - Sending a radio signal that carries time information; - Receiving a first position information determined from the radio signal; Receiving information on a magnetic map of the building; - Measuring a magnetic field at the position of the mobile device (2) by means of the magnetometer (21); - Determination of a second position specification from the measured magnetic field and the magnetic mapping of the building; - Determination of a corrected position specification from the first position specification and the second position specification. Procedure according to Claim 1 , wherein the first position information and / or the information about the magnetic mapping are called up and received from a network to which the mobile device (2) is wirelessly connected. Procedure according to Claim 1 or 2 , the corrected position information being determined by forming a weighted average value from the first position information and the second position information, weights for forming the weighted average being determined in particular from an inaccuracy of the respective position information. Mobile device (2) which has a clock (23) and a magnetometer (21) and is set up to carry out a method according to one of the preceding claims. Mobile device (2) according to Claim 4 , wherein the clock (23) is designed as an atomic clock, preferably as an atomic clock with Rb atoms, which is set up to use the hyperfine transition of the Rb atoms as a frequency standard. Mobile device (2) according to one of the Claims 4 or 5 whose magnetometer (21) has a crystal body with color centers. Mobile device (2) according to one of the Claims 4 or 5 wherein the magnetometer (21) is an optically pumped magnetometer. Mobile device (2) according to one of the Claims 4 until 7th , which also has one or more artificial neural networks that are trained to calculate an optimal corrected position information from deviations between the first position information and the second position information. Head-mounted display with a mobile device (2) according to one of the Claims 4 until 8th . Method for determining a position of a mobile device (2) within a building, at least three radio signal receivers (12A, 12B, 12C) with clocks (11A, 11B, 11C) and at least three magnetic field generators (13A, 13B, 13C) being arranged within the building are, the clocks of the receivers are synchronized with each other, comprising the steps: - When a radio signal is received by the radio signal receivers (12A, 12B, 12C), determining a first position of a transmitter of the radio signal; - Sending the determined first position; - Generating magnetic fields by the at least three magnetic field generators (13A, 13B, 13C) in such a way that a second position within the building can be determined on the basis of the magnetic field prevailing at the second position; - Providing information about the magnetic mapping of the building. Procedure according to Claim 10 , wherein the determined first position and / or the information about the magnetic mapping are sent over a network. Locating device which has at least three radio signal receivers (12A, 12B, 12C) with clocks (11A, 11B, 11C) and at least three magnetic field generators (13A, 13B, 13C), the clocks of the receivers being synchronized with one another, the locating device being set up for this purpose , a method according to one of the Claims 10 or 11th perform. Location device according to Claim 12 , wherein the clocks (11A, 11B, 11C) are designed as atomic clocks, in particular as atomic clocks with Rb atoms, which are set up to use the hyperfine transition of the Rb atoms as a frequency standard. System (100) comprising a location device according to one of the Claims 12 or 13th and a mobile device (2) according to one of the Claims 4 until 8th having. System (100) according to Claim 14 wherein the clocks (11A, 11B, 11C) of the radio signal receiver and the clock (23) of the mobile device (2) are synchronized with one another.

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