Motion-based calibration of an aerial device

Patent metadata

Field	Value
Publication number	US-12481074-B2
Application number	US-202217875850-A
Country	US
Kind code	B2
Filing date	Jul 28, 2022
Priority date	Mar 18, 2022
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

A calibration of an unmanned aerial vehicle is performed without the use of a magnetometer. The unmanned aerial vehicle generates a first acceleration vector in a navigation frame of reference and a second acceleration vector in a GPS frame of reference. The unmanned aerial vehicle estimates a heading of the unmanned aerial vehicle based on the first acceleration vector and the second acceleration vector. The unmanned aerial vehicle performs a calibration based on the estimated heading of the unmanned aerial vehicle.

First claim

What is claimed is:

1 . An unmanned aerial vehicle (UAV) comprising:
an accelerometer configured to generate acceleration signals; a gyroscope configured to generate angular rate signals; a global positioning system (GPS) sensor configured to detect GPS signals; and a processor configured to:
continually determine a global heading based on sensor data obtained from at least one of the accelerometer, the gyroscope, or the GPS sensor, wherein the global heading is a heading of the UAV in a GPS frame of reference that is based on latitude, longitude, and attitude of the UAV, and wherein the global heading includes an uncertainty value that is based on a standard deviation of measured angles of azimuth and that is continuously determined with the global heading;
determine that the uncertainty value is less than a threshold value, wherein the threshold value is a confidence value of the measured angles of azimuth;
responsive to determining that the uncertainty value is less than the threshold value:
initialize an extended Kalman filter to perform a state estimation of the UAV based on the sensor data, wherein the state estimation includes a position of the UAV, a velocity of the UAV, and an orientation of the UAV; and
calibrate at least one of the gyroscope, the accelerometer, or the GPS sensor based on the global heading.

2 . The UAV of claim 1 , wherein the measured angles of azimuth range from −180 degrees to +180 degrees.

3 . The UAV of claim 1 , wherein the processor is configured to obtain the acceleration signals from the accelerometer, the angular rate signals from the gyroscope, and the GPS signals from the GPS sensor until the uncertainty value is less than the threshold value.

4 . The UAV of claim 1 , wherein the threshold value is a measured angle of azimuth that is 15 degrees or less.

5 . The UAV of claim 1 , wherein the processor is further configured to:
generate a notification when the uncertainty value is less than the threshold value.

6 . The UAV of claim 5 , wherein the processor is further configured to:
transmit the notification to a remote device for causing a visual, audible, or haptic notification via the remote device.

7 . The UAV of claim 5 , wherein the notification comprises one or more of: a visual notification, an audible notification, and a haptic notification.

8 . The UAV of claim 7 , wherein the visual notification comprises a text display or a light emitting diode (LED) illumination.

9 . A non-transitory computer-readable medium storing instructions which, when executed by an on-board computer of an unmanned aerial vehicle (UAV), causes the on-board computer to:
obtain acceleration signals from one or more acceleration sensors and angular rate signals from one or more gyroscope sensors; fuse the acceleration signals and the angular rate signals in a complementary filter to obtain a combined signal; estimate an orientation of the UAV based on the combined signal; determine a first acceleration vector in a navigation frame of reference; determine a velocity from a global positioning system (GPS) signal; determine a second acceleration vector in a GPS frame of reference; and estimate a heading for the UAV based on the first acceleration vector and the second acceleration vector.

10 . The non-transitory computer-readable medium of claim 9 , wherein executing the instructions by the on-board computer of the UAV causes the on-board computer to:
obtain a time window of acceleration data; and perform a batch optimization to refine the estimated heading.

11 . The non-transitory computer-readable medium of claim 9 , wherein the navigation frame of reference is based on data from the one or more acceleration sensors and the one or more gyroscope sensors.

12 . The non-transitory computer-readable medium of claim 9 , wherein the combined signal is an average of the acceleration signals and the angular rate signals.

13 . The non-transitory computer-readable medium of claim 9 , wherein determining the second acceleration vector includes applying a low pass filter.

14 . The non-transitory computer-readable medium of claim 9 , wherein estimating the heading for the UAV includes recursively running a histogram filter.

15 . The non-transitory computer-readable medium of claim 14 , wherein the histogram filter provides an uncertainty value.

16 . The non-transitory computer-readable medium of claim 9 , wherein estimating the heading for the UAV includes aligning the first acceleration vector and the second acceleration vector.

17 . A method for use in an unmanned aerial vehicle (UAV), the method comprising:
obtaining acceleration signals from one or more acceleration sensors and angular rate signals from one or more gyroscope sensors; fusing the acceleration signals and the angular rate signals in a complementary filter to obtain a combined signal that is output by the complementary filter; estimating an orientation of the UAV based on the combined signal, wherein the combined signal is an average of the acceleration signals and the angular rate signals, and wherein the combined signal is tuned by assigning weights to the acceleration signals and the angular rate signals; determining a first acceleration vector in a first frame of reference based on the orientation of the UAV; determining a velocity from a global positioning system (GPS) signal; determining a second acceleration vector in a second frame of reference; and estimating a heading for the UAV based on the first acceleration vector and the second acceleration vector.

18 . The method of claim 17 , wherein the first frame of reference is a navigation frame of reference, and wherein the second frame of reference is a GPS frame of reference.

19 . The method of claim 17 , wherein determining the second acceleration vector includes applying a low pass filter.

20 . The method of claim 17 , further comprising:
obtaining a time window of acceleration from the first acceleration vector and the second acceleration vector; and refining the heading that is estimated based on the time window.

Assignees

• Skydio Inc

Inventors

• Dang Anh Tung
• Henry Peter Benjamin
• Martirosyan Hayk
• Holtz Kristen Marie
• Pattison Dominic William

Classifications

• G01S19/421

  by combining or switching between position solutions or signals derived from different satellite radio beacon positioning systems; by combining or switching between position solutions or signals derived from different modes of operation in a single system · CPC title

• G01C21/1654

  with electromagnetic compass · CPC title

• G01S19/48

  by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system · CPC title

• G01S19/52

  Determining velocity · CPC title

• G01S19/39

  the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO · CPC title