US-12625200-B2 - Navigation via magnetic field localization with pseudo-random data sequences

US12625200B2US 12625200 B2US12625200 B2US 12625200B2US-12625200-B2

Abstract

This application is directed to a local positioning system having a plurality of wire coils. Each wire coil includes one or more respective turns of wire that have a respective shape and a respective size and are arranged substantially in parallel with a respective wire plane. Each wire coil is configured to be electrically driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms according to a predefined bandwidth. For each wire coil, the respective train of pseudo-random waveforms includes a first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils. In some embodiments, a receiver system is coupled to, and measures, the magnetic field created by the wire coils during each waveform period. The location of the receiver system is determined based on measured magnetic data vectors of the magnetic field.

Inventors

Nikolai CHERNYY
Kimberly MOORE
Luca FERRARA
Andrew Ayomide Awoyemi SOSANYA

Assignees

SB Technology, Inc.

Dates

Publication Date: 20260512
Application Date: 20221012

Claims (20)

1 . A system for local positioning, comprising: a plurality of wire coils, each respective wire coil including one or more respective turns of wire, wherein: each wire coil is configured to be electrically driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms; and for each wire coil, the respective train of pseudo-random waveforms includes a first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils distinct from the respective wire coil; and a receiver system coupled to the plurality of wire coils via a magnetic field of the plurality of wire coils, wherein the receiver system is configured to: determine a respective magnetic data vector of the magnetic field in a receiver coordinate system during each waveform period, the first number of waveform periods corresponding to the first number of magnetic data vectors; obtain receiver conversion information for converting vectors in the receiver coordinate system into a reference coordinate system; obtain a local field map associating each of a plurality of locations in the magnetic field of the wire coils with a respective magnetic vector in a reference coordinate system, each location in the magnetic field of the wire coils including a respective distance and a respective direction represented with reference to the wire coils; and determine a relative location of the receiver system with reference to the plurality of wire coils using the local field map, a subset of the first number of magnetic data vectors, and the receiver conversion information.
2 . The system of claim 1 , wherein: for each wire coil, the one or more respective turns of wire have a respective shape and a respective size, and are arranged substantially in parallel with a respective wire plane; and the receiver system is configured to measure the magnetic field during each waveform period.
3 . The system of claim 1 , wherein the receiver system is configured to: determine a relative location of the receiver system with reference to the plurality of wire coils based on the magnetic field measured during each waveform period; obtain a base geographical location of the plurality of wire coils; and determine a geographical location of the receiver system based on the relative location of the receiver system and the base geographical location of the plurality of wire coils.
4 . The system of claim 1 , wherein the receiver system includes a plurality of receiver sensors configured to measure a plurality of magnetic components of the magnetic field in a receiver coordinate system having a plurality of receiver axes, and each magnetic data vector including the plurality of magnetic components projected onto the plurality of receiver axes.
5 . The system of claim 4 , wherein the receiver system further includes a reference sensor configured to identify the reference coordinate system, and the receiver conversion information includes a receiver conversion matrix for converting vectors in the receiver coordinate system to the reference coordinate system, and wherein a coil conversion matrix is used to convert vectors in a coil coordinate system to the reference coordinate system.
6 . The system of claim 4 , wherein the receiver system is configured to convert the subset of the first number of magnetic data vectors measured in the receiver coordinate system to a set of converted magnetic data vectors in the reference coordinate system using the receiver conversion information, and the relative location of the receiver system with reference to the plurality of wire coils is determined based on the set of converted magnetic data vectors in the reference coordinate system.
7 . The system of claim 1 , wherein the receiver system is configured to: convert the subset of the first number of magnetic data vectors measured in the receiver coordinate system to a set of converted magnetic data vectors in the reference coordinate system using the receiver conversion information; and identify the set of converted magnetic data vectors in the local field map, wherein the relative location of the receiver system is identified in the local field map using the set of converted magnetic data vector.
8 . The system of claim 1 , wherein a base station including the wire coils or a server system is configured to provide the local field map by, for each of a plurality of drive combinations of the wire coils: determining one or more magnetic field vectors at the plurality of locations in the magnetic field of the wire coils in a coil coordinate system; projecting the one or more magnetic field vectors to the reference coordinate system to generate a projected magnetic field vector; and determining the local field map associating each of a plurality of locations in the magnetic field of the wire coils with the respective magnetic field vector in the reference coordinate system.
9 . The system of claim 1 , wherein: the plurality of wire coils includes three identical wire coils having a same shape and a same size; for each wire coil, the one or more respective turns of wire are arranged substantially in parallel with a respective wire plane, and respective wire planes of the plurality of wire coils are perpendicular to each other and intersect at a common origin node; and respective dipole axes of the plurality of wire coils are perpendicular to each other and intersect at the common origin node.
10 . The system of claim 1 , wherein for each wire coil, the one or more respective turns of wire are arranged substantially in parallel with a respective wire plane, and at least two of the respective wire planes intersect with an angle that is not equal to 90 degrees.
11 . The system of claim 1 , wherein each of the plurality of wire coils is circular and has a predefined diameter.
12 . The system of claim 1 , wherein: at least one of the plurality of wire coils is configured to transmit a supplemental communication message; and the supplemental communication message is inserted between two repeated trains of pseudo-random waveforms.
13 . The system of claim 1 , wherein for each wire coil, the respective synchronous electric current is configured to the respective train of pseudo-random waveforms according to a predefined bandwidth that is below a frequency threshold.
14 . The system of claim 1 , further comprising a controller coupled to the plurality of wire coils, the controller configured to: determine an accuracy level of a global positioning system (GPS) in a region surrounding the plurality of wire coils; and in accordance with a determination that the accuracy level is lower than an accuracy requirement, enabling driving each of the plurality of wire coils with the respective synchronous electric current.
15 . The system of claim 1 , wherein each wire coil is configured to transmit integrity data with the respective train of pseudo-random waveforms.
16 . The system of claim 1 , wherein amplitudes of respective synchronous electric currents of the plurality of wire coils are set independently of each other.
17 . The system of claim 1 , wherein amplitudes of respective synchronous electric currents of the plurality of wire coils are equal to each other.
18 . The system of claim 1 , wherein the receiver system is configured to: convert the subset of the first number of magnetic data vectors measured in the receiver coordinate system to a set of converted magnetic data vectors in the reference coordinate system using the receiver conversion information; and identify in the local field map a set of mapping magnetic vectors, wherein the local field map does not include the set of converted magnetic data vectors, and the set of converted magnetic data vectors is substantially close to, and is interpolated from, the set of mapping magnetic vectors, wherein the relative location of the receiver system is interpolated from a set of relative locations corresponding to the set of mapping magnetic data vectors in the local field map.
19 . A method for providing a local positioning system, comprising: providing a plurality of wire coils, each respective wire coil including one or more respective turns of wire, wherein: each wire coil is configured to be electrically driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms; and for each wire coil, the respective train of pseudo-random waveforms includes a first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils distinct from the respective wire coil; and providing a receiver system coupled to the plurality of wire coils via a magnetic field of the plurality of wire coils, wherein the receiver system is configured to: determine a respective magnetic data vector of the magnetic field in a receiver coordinate system during each waveform period, the first number of waveform periods corresponding to the first number of magnetic data vectors; obtain receiver conversion information for converting vectors in the receiver coordinate system into a reference coordinate system; obtain a local field map associating each of a plurality of locations in the magnetic field of the wire coils with a respective magnetic vector in a reference coordinate system, each location in the magnetic field of the wire coils including a respective distance and a respective direction represented with reference to the wire coils; and determine a relative location of the receiver system with reference to the plurality of wire coils using the local field map, a subset of the first number of magnetic data vectors, and the receiver conversion information.
20 . A method for local positioning, comprising: at a receiver system coupled in a magnetic field of a plurality of wire coils: measuring the magnetic field during each waveform period of a first number of waveform periods; determining a respective magnetic data vector of the magnetic field in a receiver coordinate system during each waveform period, the first number of waveform periods corresponding to the first number of magnetic data vectors; obtaining receiver conversion information for converting vectors in a receiver coordinate system into a reference coordinate system; obtaining a local field map associating each of a plurality of locations in the magnetic field of the wire coils with a respective magnetic vector in the reference coordinate system, each location in the magnetic field of the wire coils including a respective distance and a respective direction represented with reference to the wire coils; and determining a relative location of the receiver system with reference to the plurality of wire coils using at least the local field map, a subset of the first number of magnetic data vectors, and the receiver conversion information; wherein the magnetic field is generated by the plurality of wire coils each of which is driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms, and for each respective wire coil, the respective train of pseudo-random waveforms includes the first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils distinct from the respective wire coil.

Description

TECHNICAL FIELD The disclosed embodiments relate generally to navigation technology, including methods and systems for navigating in a region using a local positioning system (LPS). BACKGROUND The Global Navigation Satellite System (GNSS) uses constellations of satellites to determine a receiver's location with respect to the satellites based on trilateration. Global Positioning System (GPS) is one type of GNSS that has been widely applied to provide geolocation and time information to military, civil, and commercial users around the world. Each GPS satellite continuously broadcasts a low-rate navigation message on two frequencies (i.e., 1.57542 GHz and 1.2276 GHz) at a rate of 50 bits per second. The satellite network applies a code-division multiple access (CDMA) spread-spectrum technique to encode the low-rate navigation message with a high-rate pseudo-random (PRN) sequence (i.e., Gold codes) that is different for each satellite. Satellite signals are associated with corresponding satellites based on the Gold codes, and decoded at the receiver. Despite its wide application, the GPS has a limited accuracy level in areas with poor satellite signals, and is susceptible to adversarial jamming or spoofing. As such, there is a critical need to develop positioning methods or systems that complement GPS and operate independently of GPS. SUMMARY Various embodiments of systems, methods and devices within the scope of the appended claims each have several aspects, no single one of which is solely responsible for the attributes described herein. After considering this disclosure, one will understand how the aspects of various embodiments are used for position localization in navigation operations. A base station transmitter is located at a known location and transmits to one or more distant receivers distinct actively-generated magnetic waveforms along a plurality of spatial axes (e.g., along three normal spatial axes). Properties of the corresponding magnetic field are measured and used to determine each receiver's location with respect to the base station transmitter. The magnetic waveforms are encoded using orthogonal pseudo-random sequences, and optionally transmitted with supplemental communication messages. The base station transmitter and one or more receivers form a local positioning system (LPS), which offers a desirable positioning range, signal-to-noise ratio, and synchronization performance. Such an LPS can be applied to localize a receiver system in areas having limited GPS signals to complement or replace GPS. Some embodiments of this application leverage orthogonal waveforms to drive a base station transmitter located at a known location and rely on solving for magnetic data vectors from a receiver to the base station transmitter to update the location of the receiver. In accordance with one aspect of the application, an LPS includes a plurality of wire coils. Each wire coil includes one or more respective turns of wire that have a respective shape and a respective size, and are arranged substantially in parallel with a respective wire plane. Each wire coil is configured to be electrically driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms according to a predefined bandwidth. In some embodiments, the respective synchronous electric current carries the respective train of pseudo-random waveforms according to a predefined phase. For each wire coil, the respective train of pseudo-random waveforms includes a first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils distinct from the respective wire coil. In another aspect, a method is implemented for providing an LPS. The method includes providing a plurality of wire coils. Each wire coil includes one or more respective turns of wire that have a respective shape and a respective size and are arranged substantially in parallel with a respective wire plane. Each wire coil is configured to be electrically driven by a respective synchronous electric current carrying a respective train of pseudo-random waveforms according to a predefined bandwidth. For each wire coil, the respective train of pseudo-random waveforms includes a first number of waveform periods and is orthogonal to each other train of pseudo-random waveforms of the wire coils distinct from the respective wire coil. In yet another aspect of the application, an LPS includes a receiver system located within the magnetic field of a plurality of wire coils. The receiver system is configured to measure the magnetic field during each waveform period of a first number of waveform periods and determine a respective magnetic data vector of the magnetic field during each waveform period. The first number of waveform periods corresponds to the first number of magnetic data vectors. The receiver system is configured to determine the relative location of the receiver system with reference to the pl