Utilizing magnetic field based navigation

• US 8,798,924 B2
• Filed: 01/04/2013
• Issued: 08/05/2014
• Est. Priority Date: 01/11/2012
• Status: Active Grant

• Current Assignee: IndoorAtlas Oy
• Original Assignee: IndoorAtlas Oy
• Inventors: Haverinen, Janne
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): Bendidi, Rachid
• Application Number:
  US13/734,365
• Publication Number:
  US 20130179074A1
• Time in Patent Office: 578 Days
• Field of Search: 701/400, 701/408, 701/525, 301/1, 301/2, 301/6, 301/8, 301/12, 301/14, 301/15, 301/17, 301/23, 301/25, 301/26, 301/29, 301/32, 301/33, 301/34, 301/35, 301/39, 301/40, 301/42, 301/230, 297/44, 297/40, 297/38, 297/36, 296/09, 294/192, 29/250.1
• US Class Current: 701/500
• CPC Class Codes: G01C 21/08 involving use of the magnetic field of the earth
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00
• CPC Class Codes: H04W 4/024 Guidance services
• CPC Class Codes: H04W 4/026 using orientation information, e.g. compass
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

There is provided a solution comprising detecting that a positioning device is within a predetermined control area associated with a building, acquiring a first sequence of magnetic field measurements carried out by the positioning device, wherein the first sequence represents at least one of the magnitude and the direction of Earth'"'"'s magnetic field; determining that an operational environment of the positioning de-vice has changed between an indoor environment and an outdoor environment when a at least one predetermined criterion with respect to the first sequence is met; and causing actuation of a predetermined software function in or with respect to the positioning device when the operational environment of the positioning device has changed.

Claims

1. An apparatus, comprising:

at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to;

detect that a positioning device is within a predetermined control area associated with a building;

upon detecting that the positioning device is within the predetermined control area, start acquiring a first sequence of magnetic field measurements carried out by the positioning device, wherein the first sequence represents at least one of the magnitude and the direction of Earth'"'"'s magnetic field;

determine that an operational environment of the positioning device has changed between an indoor environment and an outdoor environment when at least one predetermined criterion with respect to at least part of the first sequence is met, wherein the at least one predetermined criterion comprises a predetermined similarity between the first sequence and at least one second magnetic field sequence, wherein each second sequence is determined beforehand and represents a true magnetic field sequence for a path comprising a change of operational environment;

compare the first magnetic field sequence and the at least one second true magnetic field sequence in order to obtain at least one path hypothesis for the positioning device, wherein each path hypothesis is associated with a probability that the positioning device has traversed the path corresponding to the second magnetic field sequence; and

automatically cause a predetermined operation of an application in or with respect to the positioning device when the operational environment of the positioning device has changed, wherein the operation to be performed is based on the probabilities of the path hypotheses.

2. The apparatus of claim 1, wherein the apparatus is further caused to:

cause activation of either an application employing an indoor magnetic field based positioning system or an application employing an outdoor positioning system in the positioning device when the operational environment of the positioning device has changed, wherein the application employing the indoor magnetic field uses an indoor magnetic field map representing at least one of magnitude and direction of Earth'"'"'s magnetic field affected by the local structures of the building at a given location inside the building.

3. The apparatus of claim 1, wherein the apparatus is further caused to:

detect that the positioning device is within the control area on the basis of positioning information obtained from the outdoor positioning system and/or from the magnetic field based positioning system.

4. The apparatus of claim 1, wherein the apparatus is further caused to:

determine the direction of a true magnetic field vector for at least one position hypothesis of the positioning device, wherein the direction of the true magnetic field vector for the at least one position hypothesis is based on a predetermined magnetic field map at the at least one location corresponding to the at least one position hypothesis of the positioning device, and wherein the predetermined magnetic field map is defined in a frame of reference of the floor plan of the building; and

adjust the measured magnetic field vector direction from a frame of reference of the positioning device to the frame of reference of the floor plan the building at least partly on the basis of the direction of the true indoor magnetic field vector, wherein the measured magnetic field vector is originally defined in the frame of reference of the positioning device having an arbitrary three-dimensional orientation.

5. The apparatus of claim 1, wherein the apparatus is further caused to:

acquire motion estimate of the positioning device from at least one motion sensor coupled to the positioning device; and

apply the acquired motion estimate in order to represent the first magnetic field sequence as a function of distance with respect to the motion of the positioning device.

6. The apparatus of claim 1, wherein the at least one criterion is a predetermined change in a property derivable from the first sequence.

7. The apparatus of claim 1, wherein the apparatus is further caused to:

acquire the second true magnetic field sequence, for at least one predetermined path based on magnetic field measurements carried out by at least one measuring device, wherein each predetermined path comprises an entry to the building;

compare the first magnetic field sequence and the second true magnetic field sequence in order to obtain a path hypothesis for the positioning device; and

determine which of the at least one predetermined path the positioning device has traversed on the basis of the comparison.

8. The apparatus of claim 1, wherein the apparatus is further caused to:

detect that the operation environment of the positioning device has changed from the outdoor environment to the indoor environment;

identify the indoor location of the positioning device on the basis of a low range data transfer performed by the positioning device, wherein the low range data transfer applies at least one of the following;

a radio frequency identification technique, a Bluetooth communication protocol, a machine readable bar code, a IEEE 802.15.4 communication protocol; and

cause initialization of the positioning device with the indoor location estimate corresponding the identified location.

9. The apparatus of claim 1, wherein the apparatus is further caused to:

detect that the operation environment of the positioning device has changed from the outdoor environment to the indoor environment;

acquire information on a path the positioning device is expected to traverse and information on an expected indoor magnetic field sequence for the path, wherein the expected sequence is based on an indoor magnetic field map for the path;

acquire information on a measured indoor magnetic field based on magnetic field measurements carried out by the positioning device in the building during movement of the positioning device along the path;

determine whether the positioning device has deviated from the expected path based on a comparison between the measured indoor magnetic field and the expected indoor magnetic field sequence; and

cause actuation of a software application in or with respect to the positioning device when at least one predetermined criterion with respect to the comparison result is met.

10. The apparatus of claim 1, wherein the apparatus is further caused to:

determine a bias or a scaling factor of the measured magnetic field vector based on the difference between the measured magnetic field vector and the true magnetic field vector at the location/location hypothesis of the positioning device, wherein the true magnetic field vector is obtained from the indoor magnetic field map of the building; and

apply the determined bias in location estimation/tracking of the positioning device.

11. A method, comprising:

detecting, by a database server or by a positioning device, that the positioning device is within a predetermined control area associated with a building;

upon detecting that the positioning device is within the predetermined control area, start acquiring a first sequence of magnetic field measurements carried out by the positioning device, wherein the first sequence represents at least one of the magnitude and the direction of Earth'"'"'s magnetic field;

determining that an operational environment of the positioning device has changed between an indoor environment and an outdoor environment when a at least one predetermined criterion with respect to the first sequence is met, wherein the at least one predetermined criterion comprises a predetermined similarity between the first sequence and at least one second magnetic field sequence, wherein each second sequence is determined beforehand and represents a true magnetic field sequence for a path comprising a change of operational environment;

comparing the first magnetic field sequence and the at least one second true magnetic field sequence in order to obtain at least one path hypothesis for the positioning device, wherein each path hypothesis is associated with a probability that the positioning device has traversed the path corresponding to the second magnetic field sequence; and

automatically causing a predetermined operation of an application in or with respect to the positioning device when the operational environment of the positioning device has changed, wherein the operation to be performed is based on the probabilities of the path hypotheses.