US 9,068,843 B1Granted

Inertial sensor fusion orientation correction

AssigneeAmazon Technologies, Inc.

InventorsJung Bae Sohn, David William Devries

Life of this patent

Estimating the term…

Loading patent…

Abstract

A system for determining and correcting a calculated orientation of a computing device based on data from an accelerometer and a gyroscope. The system compares a predicted direction of gravity in a predicted frame of the device with a measured direction of gravity in a sensor frame of the device, and determines an angle of the difference between the directions. A correction is calculated to rotate the predicted frame around an axis by the angle relative to a sensor frame, the axis being perpendicular to both the predicted and measured directions of gravity. A predicted orientation of a reference “Earth” frame relative to the predicted frame is calculated based on the gyroscope data. A corrected orientation is determined by applying the correction to the predicted orientation, providing an orientation of the Earth reference frame relative to the sensor frame.

Claims20

Dependent claims

A computer-implemented method, comprising:

determining a first predicted change of orientation of a device over time by compounding a product of one-half times a previous corrected orientation with first rotational rate data based on first gyroscope data from a three-axis gyroscope of the device;
determining a first predicted orientation expressing an orientation of an Earth reference frame relative a first predicted frame of the device by adding the previous corrected orientation to a product of the first predicted change of orientation over time multiplied by a sampling rate of the three-axis gyroscope;
determining a first predictive unit vector representing a first predicted direction of gravity based on compounding a conjugate of the previous corrected orientation with a gravity vector and with the previous corrected orientation;
determining a first measured unit vector representing a first measured direction of gravity of the device based on first accelerometer data from a three-axis accelerometer of the device;
determining a first cross-product of the first predictive unit vector and the first measured unit vector, the first cross-product resulting in a first cross-product vector that is perpendicular to both the first predicted direction of gravity and the first measured direction of gravity;
determining a first angle corresponding to a difference between the first predicted direction of gravity and the first measured direction of gravity;
determining a first correction comprising a rotation of the first predicted frame of the device around the first cross-product unit vector in a sensor frame of the device by the first angle times an accelerometer jitter offset constant that is greater than zero and less than or equal to one, the accelerometer jitter offset constant set based on noise characteristics of the three-axis accelerometer;
and
determining a first corrected orientation of the device based on compounding the first predicted orientation with the first correction, the first corrected orientation expressing the Earth reference frame relative to the sensor frame.

6 more elements

A computing device comprising:

at least one processor;
a gyroscope;
an accelerometer;
a memory including instruction operable to be executed by the at least one processor to perform a set of actions to:
determine a first predicted change of orientation of the computing device based on a previous corrected orientation of the computing device and on first gyroscope data;
determine a first predicted orientation of a reference frame relative to a first predicted frame of the computing device based on the previous corrected orientation and on the first predicted change of orientation;
determine a first predicted acceleration direction of the computing device based on the previous corrected orientation of the computing device;
determine a first measured acceleration direction of the computing device based on first accelerometer data;
determine a first axis perpendicular to both the first predicted acceleration direction and the first measured acceleration direction;
determine a first angle corresponding to a first difference between the first predicted acceleration direction and the first measured acceleration direction;
determine a first correction corresponding to a first rotation of the first predicted frame of the computing device around the first axis relative to a sensor frame of the computing device based on the first angle;
and
determine a first corrected orientation expressing the reference frame relative to the sensor frame by applying the first correction to the first predicted orientation.

10 more elements

A method comprising:

determining a first predicted change of orientation of a computing device based on a previous corrected orientation of the computing device and on first gyroscope data;
determining a first predicted orientation of a reference frame relative to a first predicted frame of the computing device based on the previous corrected orientation and on the first predicted change of orientation;
determining a first predicted acceleration direction of the computing device based on the previous corrected orientation of the computing device;
determining a first measured acceleration direction of the computing device based on first accelerometer data;
determining a first axis perpendicular to both the first predicted acceleration direction and the first measured acceleration direction;
determining a first angle corresponding to a first difference between the first predicted acceleration direction and the first measured acceleration direction;
determining a first correction corresponding to a first rotation of the first predicted frame of the computing device around the first axis relative to a sensor frame of the computing device based on the first angle;
and
determining a first corrected orientation expressing the reference frame relative to the sensor frame by applying the first correction to the first predicted orientation.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/497,512Filed 26 Sep 2014
Granted: 30 Jun 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G01C 21/18
By integrating acceleration or speed, i.e. inertial navigation: stabilised platforms, e.g. by gyroscope
G06F 1/1694
Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675: the I/O peripheral…
G06F 3/03
Input arrangements or combined input and output arrangements for interaction between user and computer: arrangements for converting the position…
G06F 3/0346
Pointing devices displaced or positioned by the user , e.g. mice, trackballs, pens or joysticks; Accessories therefor: with detection of the…