UTILIZING MAGNETIC FIELD BASED NAVIGATION
First Claim
1. An indoor location estimation and/or tracking system, comprising a cellular phone and a database server, each comprising at least one processor and at least one memory including a computer program code, wherein the respective at least one memory and the respective computer program code are configured, with the respective at least one processor, to cause the respective apparatus to perform specific actions,wherein the cellular phone is caused to:
- perform Earth'"'"'s magnetic field, EMF, vector measurements in a building, wherein the EMF vector represents magnitude and direction of the earth'"'"'s magnetic field affected by the local structures of the building; and
cause transmission of the measured EMF vectors to the database server wirelessly, wherein the database server stores an indoor EMF map comprising EMF vector strength and direction at any given location in the building, andwherein the database server is caused to;
determine a location estimate of the cellular phone in the building on the basis of the received EMF vectors and the indoor EMF map; and
communicate the location estimate to the cellular phone, thereby initializing the cellular phone with the location estimate.
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Accused Products
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.
15 Citations
13 Claims
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1. An indoor location estimation and/or tracking system, comprising a cellular phone and a database server, each comprising at least one processor and at least one memory including a computer program code, wherein the respective at least one memory and the respective computer program code are configured, with the respective at least one processor, to cause the respective apparatus to perform specific actions,
wherein the cellular phone is caused to: -
perform Earth'"'"'s magnetic field, EMF, vector measurements in a building, wherein the EMF vector represents magnitude and direction of the earth'"'"'s magnetic field affected by the local structures of the building; and cause transmission of the measured EMF vectors to the database server wirelessly, wherein the database server stores an indoor EMF map comprising EMF vector strength and direction at any given location in the building, and wherein the database server is caused to; determine a location estimate of the cellular phone in the building on the basis of the received EMF vectors and the indoor EMF map; and communicate the location estimate to the cellular phone, thereby initializing the cellular phone with the location estimate. - View Dependent Claims (5, 6, 7, 8, 10, 11)
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2. The indoor location estimation and/or tracking system of claim wherein the database server is caused to:
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acquire motion estimate of the cellular phone from at as one motion sensor coupled to the cellular phone; and determine a motion model on the basis of the motion estimate; and apply the motion model for at least one location hypothesis of the cellular phone in order to determine the location estimate of the cellular phone.
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3. The indoor location estimation and/or tracking system f claim wherein the database server is caused to:
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acquire motion data of the cellular phone from at least one motion sensor coupled to the cellular phone, wherein the cellular phone has an arbitrary three-dimensional orientation; perform orientation adjustment of the cellular phone from the frame of reference of the cellular phone to a predetermined frame of reference, wherein the adjustment is based at least partly on the known direction of the gravitational force and the received motion data; and correct the received EMF vector on the basis of the orientation adjustment, wherein the received EMF vector is originally measured in the frame of reference of the cellular phone having the arbitrary three-dimensional orientation.
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4. The indoor location estimation and/or tracking system of claim wherein the database server is further caused to:
determine the amount of rotation about the orthogonal horizontal coordinate axes by applying the known direction of the gravitational force and the motion data.
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9. The indoor location estimation and/or tracking system of lain wherein the database server is further caused to:
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determine a bias and/or a scaling factor of the received EMF vector based on the difference between the received magnetic field vector and the true magnetic field vector at the location or location hypothesis of the cellular phone, wherein the true magnetic field vector is obtained from the EMF map of the building; and apply the determined bias and/or the scaling factor in location estimation and or tracking of the cellular phone.
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12. A cellular phone for use in an indoor location estimation and/or tracking system, the cellular phone 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, with the at least one processor, to cause the cellular phone to:
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perform Earth'"'"'s magnetic field, EMF, vector measurements in a building, wherein the EMF vector represents magnitude and direction of the earth'"'"'s magnetic field affected by the local structures of the building; cause transmission of the measured EMF vectors to the database sever wirelessly, wherein the database server stores an indoor EMF map comprising EMF vector strength and direction at any given location in the building; and cause reception of a location estimate from the database server, thereby initializing the cellular phone with the location estimate.
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13. A database server for use in an indoor location estimation and/or tracking system, the database server 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, with the at least one processor, to cause the database server to:
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receive Earth'"'"'s magnetic field, EMF, vectors measured by a cellular phone in a building, wherein the EMF vector represents magnitude and direction of the earth'"'"'s agnetic field affected by the local structures of the building; determine a location estimate of the cellular phone in the building on the basis of the received EMF vectors and an indoor EMF map, wherein the database server stores the indoor EMF map comprising EMF vector strength and direction at any given location in the building; and communicate the location estimate to the cellular phone, thereby initializing the cellular phone with the location estimate.
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Specification