Drift-free velocity estimation for multirotor systems and localization thereof

Patent metadata

Field	Value
Publication number	US-11525683-B2
Application number	US-201916254303-A
Country	US
Kind code	B2
Filing date	Jan 22, 2019
Priority date	Sep 21, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

Embodiments of the present disclosure provide systems and methods to eliminate (or filter) drift for dynamics model based localization of multirotors. The dynamics equations require drag modelling, which is dependent on velocity, to generate vehicles' acceleration along the body axis. The present disclosure considers the drag contribution, at velocity level, as a low frequency component. Incorrect or nonmodelling of this low frequency component leads to drift at velocity level. This drift can then be removed through a high pass filter to obtain drift free velocity data for pose estimation and better localization thereof.

First claim

What is claimed is:

1. A processor implemented method, comprising:
receiving, via one or more hardware processors, gyroscope data pertaining to a multirotor system ( 302 ), wherein the gyroscope data comprises Euler angles indicative of orientation of the multirotor system; computing via the one or more hardware processors, using Euler angles, acceleration data based on a multirotor dynamics model ( 304 );
estimating, via the one or more hardware processors, velocity based on the acceleration data ( 306 ) to obtain velocity data;
determining, via the one or more hardware processors, frequency of drift caused due to inexact or non-modelling of drag force in the estimated velocity by transforming the velocity data to a frequency domain through a Fast Fourier Transform (FFT) to obtain a cut off frequency that separates a drift from the velocity in the frequency domain, wherein the cut off frequency is obtained from a frequency of a received data stream synchronized in time through a ROS (Robot Operating System) message filter with messages including pose data consisting of a position and the orientation of the multirotor system taken as input at a fixed frequency, wherein the frequency of output messages from the ROS message filter is changed to a synchronous frequency that is synchronous with similar messages obtained from a system, wherein the cut off frequency is 0.1% of the synchronous frequency, and wherein the drag force is identified as a low frequency component ( 308 ); and
eliminating, using a band pass filter, the drift from the velocity by applying the band pass filter on the drag force identified as the low frequency component, to obtain drift-free velocity data ( 310 ).

2. The processor implemented method of claim 1 , further comprising regenerating, using the drift-free velocity data, a pose of the multirotor system and localization thereof ( 312 ).

3. A system ( 100 ), comprising:
a memory ( 102 ) storing instructions;
one or more communication interfaces ( 106 ); and
one or more hardware processors ( 104 ) coupled to the memory ( 102 ) via the one or more communication interfaces ( 106 ), wherein the one or more hardware processors ( 104 ) are configured by the instructions to:
receive, gyroscope data pertaining to a multirotor system, wherein the gyroscope data comprises Euler angles indicative of orientation of the multirotor system;
compute, using Euler angles, acceleration data based on a multirotor dynamics model;
estimate velocity based on the acceleration data to obtain velocity data;
determine frequency of drift caused due to inexact or non-modelling of drag force in the estimated velocity by transforming the velocity data to a frequency domain through a Fast Fourier Transform (FFT) to obtain a cut off frequency that separates a drift from the velocity in the frequency domain, wherein the cut off frequency is obtained from a frequency of a received data stream synchronized in time through a ROS (Robot Operating System) message filter with messages including pose data consisting of a position and the orientation of the multirotor system taken as input at a fixed frequency, wherein the frequency of output messages from the ROS message filter is changed to a synchronous frequency that is synchronous with similar messages obtained from a system, wherein the cut off frequency is 0.1% of the synchronous frequency, and wherein the drag force is identified as a low frequency component; and
eliminate, using a band pass filter, the drift from the velocity by applying the band pass filter on the drag force identified as the low frequency component, to obtain drift-free velocity data.

4. The system of claim 3 , wherein the one or more hardware processors are further configured to regenerate, using the drift-free velocity data, a pose of the multirotor system and localize thereof.

5. One or more non-transitory machine readable information storage mediums comprising one or more instructions which when executed by one or more hardware processors cause:
receiving, via the one or more hardware processors, gyroscope data pertaining to a multirotor system, wherein the gyroscope data comprises Euler angles indicative of orientation of the multirotor system;
computing via the one or more hardware processors, using Euler angles, acceleration data based on a multirotor dynamics model;
estimating, via the one or more hardware processors, velocity based on the acceleration data to obtain velocity data;
determining, via the one or more hardware processors, frequency of drift caused due to inexact or non-modelling of drag force in the estimated velocity by transforming the velocity data to a frequency domain through a Fast Fourier Transform (FFT) to obtain a cut off frequency that separates a drift from the velocity in the frequency domain, wherein the cut off frequency is obtained from a frequency of a received data stream synchronized in time through a ROS (Robot Operating System) message filter with messages including pose data consisting of a position and the orientation of the multirotor system taken as input at a fixed frequency, wherein the frequency of output messages from the ROS message filter is changed to a synchronous frequency that is synchronous with similar messages obtained from a system, wherein the cut off frequency is 0.1% of the synchronous frequency, and wherein the drag force is identified as a low frequency component; and
eliminating, using a band pass filter, the drift from the velocity by applying the band pass filter on the drag force identified as the low frequency component, to obtain drift-free velocity data.

6. The one or more non-transitory machine readable information storage mediums of claim 5 , wherein the instructions further cause: regenerating, using the drift-free velocity data, a pose of the multirotor system and localization thereof.

Assignees

• Tata Consultancy Services Ltd

Inventors

• Rustagi Vishvendra
• Ludhiyani Mohit
• Sinha Arnab
• Dasgupta Ranjan

Classifications

• B64U2201/10

  autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] · CPC title

• B64U2101/30

  for imaging, photography or videography · CPC title

• G01P15/14

  by making use of gyroscopes (gyroscopes per se G01C19/00) · CPC title

• G01C21/183 Primary

  Compensation of inertial measurements, e.g. for temperature effects · CPC title

• G06F17/16

  Matrix or vector computation {, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization (matrix transposition G06F7/78)} · CPC title