# US 10,371,516 B2 · Method and apparatus for determination of misalignment between device and pedestrian

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- Number: US 10,371,516 B2
- Document ID: US10371516B2
- Status: Granted
- Kind: B2
- Application number: 14/761,156
- Filed: 2014-01-21
- Published: 2015-12-10
- Granted: 2019-08-06
- Earliest claimed: 2013-01-21
- Assignees: InvenSense, Inc.
- Applicants: Trusted Positioning, Inc.
- Inventors: Abdelrahman Ali; Hsiu-Wen Chang; Jacques Georgy; Zainab Syed; Christopher Goodall
- Web page: https://patentgrep.com/patent/US10371516B2

## CPC

- G01B 21/24: for testing alignment of axes
- G01C 21/185: {for gravity}
- G01P 15/18: in two or more dimensions
- G06F 3/0346: with detection of the device orientation or free movement in a three-dimensional [3D] space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- 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)
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

The present disclosure relates to a method and apparatus for determining the misalignment between a device and a pedestrian, wherein the pedestrian can carry, hold, or use the device in different orientations in a constrained or unconstrained manner, and wherein the device comprises a sensor assembly. The sensors in the device may be for example, accelerometers, gyroscopes, magnetometers, barometer among others. The sensors have a corresponding frame for the sensors' axes. The misalignment between the device and the pedestrian means the misalignment between the frame of the sensor assembly in the device and the frame of the pedestrian. The present method and apparatus can work whether in the presence or in the absence of absolute navigational information updates (such as, for example, Global Navigation Satellite System (GNSS) or WiFi positioning).

## Claims

### Claim 1

A method for enhancing a navigation solution of a device and a pedestrian by determining misalignment between the device and the pedestrian, wherein the misalignment is a heading misalignment angle between a heading of the device and a heading of the pedestrian, wherein the heading of the pedestrian is a pedestrian direction of motion, wherein the device comprises a tri-axial accelerometer and at least one processor, and wherein the method is operable when the device is associated with the pedestrian in a constrained manner and when the device is associated with the pedestrian in an unconstrained manner, such that the device is tiltable to any orientation, the method comprising using the at least one processor to perform the steps of:
a) calculating a plurality of levelled accelerometer readings from readings of the tri-axial accelerometer by transforming the tri-axial accelerometer readings into a levelled vertical accelerometer reading component and first and second horizontal acceleration components;
b) generating a vertical acceleration component from the levelled vertical accelerometer reading component;
c) calculating an along-track angle based at least in part on the first and second horizontal acceleration components, wherein the along-track angle is one of a forward or a backward direction of the heading misalignment angle;
d) determining a use case of the device based at least in part on the levelled acceleration components, wherein the use case of the device represents how the device is associated with the pedestrian;
e) detecting if a 180 degrees error in the calculated along-track angle is present based on the determined use case, wherein one or more techniques for detecting if the 180 degrees error is present are selected from multiple techniques based on the use case; and
f) calculating a misalignment angle from the along-track angle and, if present, the 180 degrees error.

### Claim 2 (depends on 1)

The method of claim 1, wherein calculating an along-track angle comprises applying a maximum possible variance technique on the first and second horizontal acceleration components.

### Claim 3 (depends on 1)

The method of claim 1, wherein calculating an along-track angle comprises the steps of:
a) applying a Principal Component Analysis on the first and second horizontal acceleration components;
b) calculating an along-track angle using outputs of the Principal Component Analysis; and
c) transforming the horizontal acceleration components using the along-track angle to generate an along-track acceleration component and a cross-track acceleration component;
wherein step e) of claim 1 further comprises detecting if the 180 degrees error in the along-track angle is present based on the use case, the along-track acceleration component and the vertical acceleration component.

### Claim 4 (depends on 1)

The method of claim 1, wherein calculating an along-track angle comprises the steps of:
a) applying a Principal Component Analysis on the first and second horizontal acceleration components;
b) calculating an along-track angle using outputs of the Principal Component Analysis; and
c) transforming the horizontal acceleration components using the along-track angle to generate an along-track acceleration component and a cross-track acceleration component;
wherein step e) of claim 1 further comprises detecting if the 180 degrees error in the along-track angle is present based on the use case, the along-track acceleration component and the vertical acceleration component, or declaring no decision; and
wherein step f) of claim 1 further comprises calculating the misalignment angle, in case e) does not declare no decision, from the along-track angle and, if present, the 180 degrees error.

### Claim 5 (depends on 3)

The method of claim 3, wherein the detection if a 180 degrees error is present in the along-track angle is further based on one or more of the following components selected from: the cross-track acceleration component, the magnitude of the first and second horizontal acceleration components, or the magnitude of the first and second horizontal and the vertical acceleration components.

### Claim 6 (depends on 4)

The method of claim 4, wherein if the method declares no decision, then further using buffered information to calculate the misalignment angle.

### Claim 7 (depends on 4)

The method of claim 4, wherein the detection if a 180 degrees error is present in the along-track angle is further based on one or more of the following components selected from: the cross-track acceleration component, the magnitude of the first and second horizontal acceleration components, or the magnitude of the first and second horizontal and the vertical acceleration components.

### Claim 8

A device portable by a pedestrian for enhancing a navigation solution of a device and a pedestrian by determining misalignment between the device and the pedestrian, wherein the misalignment is a heading misalignment angle between a heading of the device and a heading of the pedestrian and wherein the heading of the pedestrian is a pedestrian direction of motion, the device comprising:
a) a tri-axial accelerometer; and
b) a processor, coupled to receive readings from the tri-axial accelerometer, and operative to determine the misalignment between the device and the pedestrian and wherein the processor is operable when the device is associated with the pedestrian in a constrained manner and when the device is associated with the pedestrian in an unconstrained manner, such that the device is tiltable to any orientation, wherein the processor is operative to:
i) calculate a plurality of levelled accelerometer readings from readings of the tri-axial accelerometer by transforming the tri-axial accelerometer readings into a levelled vertical accelerometer reading component and first and second horizontal acceleration components;
ii) generate a vertical acceleration component from the levelled vertical accelerometer reading component;
iii) calculate an along-track angle based at least in part on the first and second horizontal acceleration components, wherein the along-track angle is one of a forward or a backward direction of the heading misalignment angle;
iv) determine a use case of the device based at least in part on the levelled acceleration components, wherein the use case of the device represents how the device is associated with the pedestrian;
v) determine if a 180 degrees error in the calculated along-track angle is present based on the determined use case, wherein one or more techniques for determining if the 180 degrees error is present are selected from multiple techniques based on the use case; and
vi) calculate a misalignment angle from the along-track angle and, if present, the 180 degrees error.

### Claim 9 (depends on 8)

The device of claim 8, wherein the processor is operative to calculate an along-track angle by applying a maximum possible variance technique on the first and second acceleration components.

### Claim 10 (depends on 2, 3, 4, 5, 6)

The method of any one of claim 2, 3, 4, 5, 6, or 7, wherein the method further comprises at least one of: i) enhancing the misalignment angle using self-contained information; ii) enhancing the calculated misalignment angle from absolute navigational information; and iii) calculating a standard deviation for the calculated misalignment angle.