# US 8,751,151 B2 · System and method for localizing a trackee at a location and mapping the location using inertial sensor information

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- Number: US 8,751,151 B2
- Document ID: US8751151B2
- Status: Granted
- Kind: B2
- Application number: 13/852,649
- Filed: 2013-03-28
- Published: 2013-12-12
- Granted: 2014-06-10
- Earliest claimed: 2012-06-12
- Assignees: Trx Systems, Inc.
- Applicants: TRX Systems, Inc
- Inventors: Benjamin E. Funk; Jared Napora; Kamiar Kordari; Ruchika Verma; Amrit Bandyopadhyay; Carole Teolis
- Web page: https://patentgrep.com/patent/US8751151B2

## CPC

- G01C 21/206: {specially adapted for indoor navigation}
- G01C 21/1652: {with ranging devices, e.g. LIDAR or RADAR}
- G01C 21/1654: {with electromagnetic compass}
- G01C 21/1656: {with passive imaging devices, e.g. cameras}
- G01C 21/3844: {Data obtained from position sensors only, e.g. from inertial navigation}
- G01C 21/3848: {Data obtained from both position sensors and additional sensors}
- G01S 5/012: {Identifying whether indoors or outdoors}
- G01S 5/014: {Identifying transitions between environments}
- G01S 5/015: {between indoor and outdoor environments}
- G01S 19/13: Receivers
- G01S 19/39: the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A system and method for recognizing features for location correction in Simultaneous Localization And Mapping operations, thus facilitating longer duration navigation, is provided. The system may detect features from magnetic, inertial, GPS, light sensors, and/or other sensors that can be associated with a location and recognized when revisited. Feature detection may be implemented on a generally portable tracking system, which may facilitate the use of higher sample rate data for more precise localization of features, improved tracking when network communications are unavailable, and improved ability of the tracking system to act as a smart standalone positioning system to provide rich input to higher level navigation algorithms/systems. The system may detect a transition from structured (such as indoors, in caves, etc.) to unstructured (such as outdoor) environments and from pedestrian motion to travel in a vehicle. The system may include an integrated self-tracking unit that can localize and self-correct such localizations.

## Claims

### Claim 1

A computer-implemented method of localizing a trackee at a location and generating or updating a map of the location based on inertial sensor information, the method being implemented on a computer system that includes one or more physical processors programmed by one or more modules, the method comprising:
identifying, by a feature detection module, at least one sensor feature based on inertial sensor information that includes a plurality of measurements that measure a motion of the trackee at the location, the at least one sensor feature being identified based on a first subset of the plurality of measurements;
identifying, by the feature detection module, a structural feature of the location using only the at least one sensor feature;
determining, by a localization and mapping module, a location estimate that estimates a location of the trackee based on at least a second subset of the plurality of measurements that is the same as or different from the first subset of the plurality of measurements, wherein a position of the structural feature is determined based on the location estimate; and
generating or updating, by the localization and mapping module, a map of the location based on the structural feature.

### Claim 2 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
recognizing, by the feature detection module, the at least one sensor feature based on at least a portion of a second plurality of measurements that was obtained in relation to a re-visit to the structural feature;
obtaining, by the localization and mapping module, the position of the structural feature;
determining, by the localization and mapping module, a second location estimate that estimates a location of the trackee based on at least a first subset of the second plurality of measurements; and
updating, by the localization and mapping module, the second location estimate based on the position of the structural feature.

### Claim 3 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
generating, by a feature message module, a feature message that describes the structural feature, wherein generating or updating the map of the location comprises generating or updating, by the localization and mapping module, the map of the location based on information related to the structural feature conveyed by the feature message.

### Claim 4 (depends on 1)

The computer-implemented method of claim 1, wherein correlating the at least one sensor feature with a structural feature of the location comprises:
determining, by the feature detection module, that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) linear and horizontal within a threshold range, and (ii) does not change in elevation; and
correlating, by the feature detection module, the at least one sensor feature with a hallway of a building based on the indicated path.

### Claim 5 (depends on 1)

The computer-implemented method of claim 1, wherein correlating the at least one sensor feature with a structural feature of the location comprises:
determining, by the feature detection module, that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) vertical that changes in elevation, and (ii) includes no horizontal movements or horizontal movements below a threshold value; and
correlating, by the feature detection module, the at least one sensor feature with an elevator based on the indicated path.

### Claim 6 (depends on 1)

The computer-implemented method of claim 1, wherein correlating the at least one sensor feature with a structural feature of the location comprises:
determining, by the feature detection module, that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) vertical that changes in elevation, and (ii) includes horizontal movements above a threshold value; and
correlating, by the feature detection module, the at least one sensor feature with a stairwell based on the indicated path.

### Claim 7 (depends on 1)

The computer-implemented method of claim 1, wherein correlating the at least one sensor feature with a structural feature of the location comprises:
determining, by the feature detection module, that at least a first portion of the plurality of measurements related to the motion indicates a first path that is: (i) linear and horizontal within a threshold range, and (ii) does not change in elevation;
correlating, by the feature detection module, the at least one sensor feature with a hallway of a building based on the indicated path, wherein the method further comprises:
determining, by the feature detection module, that at least a second portion of the plurality of measurements related to the motion indicates a second path that is: (i) vertical that changes in elevation, and (ii) includes no horizontal movements or horizontal movements below a threshold value;
correlating, by the feature detection module, the at least one sensor feature with an elevator based on the second path;
determining, by the feature detection module, that at least a first portion of the plurality of measurements related to the motion indicates a third path that is: (i) vertical that changes in elevation, and (ii) includes horizontal movements above a threshold value; and
correlating, by the feature detection module, the at least one sensor feature with a stairwell based on the third path.

### Claim 8 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
detecting, by a location transition module, a transition from inside a structure to outside the structure or outside the structure to inside the structure based on sensor information that indicates a difference between inside the structure and outside the structure; and
generating or updating, by the localization and mapping module, the map of the location based on the transition.

### Claim 9 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
identifying, by the feature detection module, at least one second sensor feature based on sensor information that is not inertial sensor information;
correlating, by the feature detection module, the at least one second sensor feature with a second structural feature of the location, wherein the second structural feature is the same as or different from the structural feature, wherein generating the map comprises generating, by the localization and mapping module, the map based on the second structural feature.

### Claim 10 (depends on 9)

The computer-implemented method of claim 9, wherein the structural feature and the second structural feature are the same feature such that at least two different types of sensors are used to identify the structural feature.

### Claim 11 (depends on 9)

The computer-implemented method of claim 9, wherein the structural feature is different from the second structural feature such that different structural features are identified by respective different types of sensors.

### Claim 12 (depends on 1)

The computer-implemented method of claim of claim 1, the method further comprising:
communicating, by the feature detection module, the sensor information to a remote device for further localization and mapping at the remote device.

### Claim 13

A system for localizing a trackee at a location and generating or updating a map of the location based on inertial sensor information, the system comprising:
one or more processors configured to execute computer program modules, the computer program modules comprising:
a feature detection module programmed to:
identify at least one sensor feature based on inertial sensor information that includes a plurality of measurements that measure a motion of the trackee at the location, the at least one sensor feature being identified based on a first subset of the plurality of measurements;
identify a structural feature of the location using only the at least one sensor feature; and
a localization and mapping module programmed to:
determine a location estimate that estimates a location of the trackee based on at least a second subset of the plurality of measurements that is the same as or different from the first subset of the plurality of measurements, wherein a position of the structural feature is determined based on the location estimate; and
generate or update a map of the location based on the structural feature.

### Claim 14 (depends on 13)

The system of claim 13, wherein the feature detection module is further programmed to:
recognize the at least one sensor feature based on at least a portion of a second plurality of measurements that was obtained in relation to a re-visit to the structural feature, and wherein the localization and mapping module is further programmed to:
obtain the position of the structural feature;
determine a second location estimate that estimates a location of the trackee based on at least a first subset of the second plurality of measurements; and
update the second location estimate based on the position of the structural feature.

### Claim 15 (depends on 13)

The system of claim 13, the computer program modules further comprising:
a feature message module programmed to generate a feature message that describes the structural feature, wherein the map of the location is generated based on information related to the structural feature conveyed by the feature message.

### Claim 16 (depends on 13)

The system of claim 13, wherein the feature detection module is further programmed to:
determine that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) linear and horizontal within a threshold range, and (ii) does not change in elevation; and
correlate the at least one sensor feature with a hallway of a building based on the indicated path.

### Claim 17 (depends on 13)

The system of claim 13, wherein the feature detection module is further programmed to:
determine that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) vertical that changes in elevation, and (ii) includes no horizontal movements or horizontal movements below a threshold value; and
correlate the at least one sensor feature with an elevator based on the indicated path.

### Claim 18 (depends on 13)

The system of claim 13, wherein the feature detection module is further programmed to:
determine that at least a first portion of the plurality of measurements related to the motion indicates a path that is: (i) vertical that changes in elevation, and (ii) includes horizontal movements above a threshold value; and
correlate the at least one sensor feature with a stairwell based on the indicated path.

### Claim 19 (depends on 13)

The system of claim 13, wherein the feature detection module is further programmed to:
determine that at least a first portion of the plurality of measurements related to the motion indicates a first path that is: (i) linear and horizontal within a threshold range, and (ii) does not change in elevation;
correlate the at least one sensor feature with a hallway of a building based on the indicated path, wherein the method further comprises:
determine that at least a second portion of the plurality of measurements related to the motion indicates a second path that is: (i) vertical that changes in elevation, and (ii) includes no horizontal movements or horizontal movements below a threshold value;
correlate the at least one sensor feature with an elevator based on the second path;
determine that at least a first portion of the plurality of measurements related to the motion indicates a third path that is: (i) vertical that changes in elevation, and (ii) includes horizontal movements above a threshold value; and
correlate the at least one sensor feature with a stairwell based on the third path.

### Claim 20 (depends on 13)

The system of claim 13, the computer program modules further comprising:
a location transition module programmed to detect a transition from inside a structure to outside the structure or outside the structure to inside the structure based on sensor information that indicates a difference between inside the structure and outside the structure, wherein the map of the location is generated based further on the transition.

### Claim 21 (depends on 14)

The system of claim 14, wherein the feature detection module is further programmed to:
identify at least one second sensor feature based on sensor information that is not inertial sensor information;
correlate the at least one second sensor feature with a second structural feature of the location, wherein the second structural feature is the same as or different from structural feature, wherein the map is generated based on the second structural feature.

### Claim 22 (depends on 21)

The system of claim 21, wherein the structural feature and the second structural feature are the same feature such that at least types of sensors are used to identify the structural feature.

### Claim 23 (depends on 21)

The system of claim 21, wherein the structural feature is different from the second structural feature such that different structural features are identified by respective different types of sensors.

### Claim 24 (depends on 13)

The system of claim of claim 13, wherein the feature detection module is further configured to communicate the sensor information to a remote device for further localization and mapping at the remote device.

### Claim 25

A computer readable storage media comprising executable code for localizing a trackee at a location and generating or updating a map of the location based on inertial sensor information, the computer executable code, when executed by one or more processors, causing the one or more processors to:
identify at least one sensor feature based on inertial sensor information that includes a plurality of measurements that measure a motion of the trackee at the location, the at least one sensor feature being identified based on a first subset of the plurality of measurements;
identify a structural feature of the location using only the at least one sensor feature;
determine a location estimate that estimates a location of the trackee based on at least a second subset of the plurality of measurements that is the same as or different from the first subset of the plurality of measurements, wherein a position of the structural feature is determined based on the location estimate; and
generate or update a map of the location based on the structural feature.