Dead reconing system based on locally measured movement

Patent metadata

Field	Value
Publication number	US-9602974-B2
Application number	US-201414268993-A
Country	US
Kind code	B2
Filing date	May 2, 2014
Priority date	Dec 28, 2012
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A Global Navigation Satellite System (GNSS) chipset embedded within the cellular device is accessed. The GNSS chipset calculates raw pseudoranges. The raw pseudoranges are extracted from the GNSS chipset for processing elsewhere in the cellular device outside of the GNSS chipset. A position fix is calculated based on the raw pseudoranges. At a first point in time, a first image, and at a second point in time, a second image are obtained with an image capturing device that is in a known physical relationship with the cellular device. An estimate of a distance that the cellular device moved from the first point in time to the second point in time is calculated by processing image data collected from the first point in time to the second point in time. The position fix is processed based on the estimate of the distance.

First claim

What is claimed is:

1. A method of improving position determination of a cellular device using locally measured movement, the method comprising:
accessing a Global Navigation Satellite System (GNSS) chipset embedded within the cellular device, wherein the GNSS chipset calculates raw pseudoranges;
extracting the raw pseudoranges from the GNSS chipset for processing elsewhere in the cellular device outside of the GNSS chipset;
calculating a position fix based on the raw pseudoranges;
obtaining, at a first point in time, a first image with an image capturing device that is in a known physical relationship with the cellular device;
obtaining, at a second point in time, a second image with the image capturing device;
calculating an estimate of a distance that the cellular device moved from the first point in time to the second point in time by processing image data collected for a time frame from the first point in time to the second point in time; and
processing the position fix based on the estimate of the distance,
wherein the accessing, the extracting, the calculating of the position fix, the obtaining the first image, the obtaining the second image, the calculating of the estimate, and the processing of the position fix are performed by one or more hardware processors located in the cellular device and outside of the GNSS chipset.

2. The method as recited by claim 1 , wherein the estimate is a first estimate and wherein the method further comprises:
obtaining, at the first point in time, first accelerometer data from an accelerometer that is part of the cellular device;
obtaining, at the second point in time, second accelerometer data from the accelerometer;
calculating a second estimate of the distance based on the first accelerometer data and the second accelerometer data; and
determining a third estimate by blending the first estimate and the second estimate using a filter,
wherein the obtaining of the first accelerometer data, the obtaining of the second accelerometer data, the calculating of the second estimate and the determining of the third estimate are performed by the one or more hardware processors.

3. The method as recited by claim 1 , wherein the processing of the position fix further comprises:
determining whether to discard the position fix based on the estimate of the distance; and
if the position fix is discarded,
interpolating a new position fix based on the distance and two or more position fixes that precede the discarded position fix; and
replacing the discarded position fix with the new position fix,
wherein the determining whether to discard, the interpolating and the replacing are performed by the one or more hardware processors.

4. The method as recited by claim 3 , wherein the raw pseudoranges are current raw pseudoranges, wherein the position fix is a current position fix at the second point in time, and wherein the method further comprises:
extracting previous raw pseudoranges from the GNSS chipset, wherein the previous raw pseudoranges are extracted before the current raw pseudoranges are extracted;
determining a previous position fix, for the first point in time, based on the previous raw pseudoranges;
determining a position fix distance that is a difference between the current position fix and the previous position fix;
determining a second difference between the estimate of the distance and the position fix distance; and
if the second difference exceeds a metric threshold, discarding the current position fix,
wherein the extracting of the previous raw pseudoranges, the determining of the previous position fix, the determining of the position fix distance, the determining of the second difference and the discarding of the current position fix are performed by the one or more hardware processors.

5. The method as recited by claim 4 , wherein the position fix is a current position fix of the cellular device and wherein the interpolating of the new position fix further comprises:
determining a trajectory of movement of the cellular device based on two or more position fixes, which are previous to the current position fix, of the cellular device; and
interpolating the new position fix based on the estimate of the distance and the trajectory.

6. The method as recited by claim 1 , wherein the calculating of the estimate of the distance that the cellular device moved from the first point in time to the second point in time by processing image data collected for the time frame from the first point in time to the second point in time further comprises:
replacing a set of image data related to at least five key-points included in the first image with a set of image data related to at least five same key-points included in the second image.

7. The method as recited by claim 1 , wherein the obtaining, at the first point in time, of the first image with the image capturing device further comprises:
calibrating the image capturing device to correct the image for lens distortion, the lens distortion selected from a group consisting of a principal distance distortion, a focal length, a principal point offset, a radial distortion, and a tangential distortion.

8. The method as recited by claim 1 , wherein the calculating the estimate of the distance that the cellular device moved from the first point in time to the second point in time by processing image data collected for the time frame from the first point in time to the second point in time further comprises:
calculating the estimate of the distance that the cellular device moved from the first point in time to the second point in time by processing image data collected for the time frame from the first point in time to the second point in time using a sequential rolling bundle adjustment algorithm.

9. The method as recited by claim 1 , wherein the position fix is a current position fix of the cellular device and wherein the method further comprises:
obtaining a set of images 1 to n using the image capturing device from at least the first point in time to the second point in time, each image of the set of images 1 to n includes a set of image data and images 1 to n−1 has at least one respective subsequent image and images 2 to n has at least one respective previous image;
calculating position fix estimates of positions of the cellular device between the first point in time and the second point in time by replacing a set of image data included in an image with a set of image data included in a respective subsequent image;
determining a previous position fix, based on previous raw pseudoranges, wherein the previous position fix correlates with a position of the cellular device at a time that is less than or equal to the second point in time; and
determining the estimate of the distance based on the previous position fix and at least one of the position fix estimates.

10. A system for improving position determination of a cellular device using locally measured movement, the system comprising:
accessing logic that accesses a Global Navigation Satellite System (GNSS) chipset embedded within the cellular device, wherein the GNSS chipset calculates raw pseudoranges;
extracting logic that extracts the raw pseudoranges from the GNSS chipset for processing elsewhere in the cellular device outside of the GNSS chipset;
position fix determining logic that calculates a position fix based on the raw pseudoranges;
image capturing device movement information accessing logic that obtains, at a first point in time, a first image with an image capturing device that is in a known physical relationship with the cellular device and that obtains, at a second point in time, a second image with the image capturing device; and

Assignees

• Trimble Navigation Ltd
• Trimble Inc

Inventors

• Rudow Richard
• Wold Robert
• Kasirajan Venkateswaran
• Talbot Nicholas C
• Loomis Peter Van Wyck
• Weisenburger Shawn D
• Janky James M

Classifications

• G01S19/09

  providing processing capability normally carried out by the receiver · CPC title

• G01S19/43

  using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry · CPC title

• H04W4/027

  using movement velocity, acceleration information · CPC title

• H04W4/023

  using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds · CPC title

• H04W64/00

  Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management · CPC title