System and method of multirotor dynamics based online scale estimation for monocular vision

Patent metadata

Field	Value
Publication number	US-10748299-B2
Application number	US-201916580403-A
Country	US
Kind code	B2
Filing date	Sep 24, 2019
Priority date	Sep 24, 2018
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

Robotic vision-based framework wherein an on-board camera device is used for scale estimation. Unlike conventional scale estimation methods that require inputs from more than one or more sensors, implementations include a system and method to estimate scale online solely, without any other sensor, for monocular SLAM by using multirotor dynamics model in an extended Kalman filter framework. This approach improves over convention scale estimation methods which require information from some other sensors or knowledge of physical dimension of an object within the camera view. An arbitrary scaled position and an Euler angle of a multirotor are estimated from vision SLAM (simultaneous localization and mapping) technique. Further, dynamically integrating, computed acceleration to estimate a metric position. A scale factor and a parameter associated with the multirotor dynamics model is obtained by comparing the estimated metric position with the estimated arbitrary position.

First claim

What is claimed is:

1. A processor-implemented method of estimating online scale for a monocular SLAM, comprising:
estimating, using a monocular camera, an arbitrary scaled position of a multirotor based on a vision SLAM (simultaneous localization and mapping) technique in an inertial frame;
inputting, to a multirotor dynamics-based predictor, an Euler angle estimated from the vision SLAM technique to compute an acceleration of the multirotor;
dynamically integrating the computed acceleration to estimate a metric velocity and a metric position;
comparing the estimated metric position with the estimated arbitrary position from the vision SLAM technique; and
estimating a scale factor and a parameter associated with a multirotor dynamics model, wherein the parameter associated with the multirotor dynamics model is a drag coefficient.

2. The processor-implemented method of claim 1 , wherein the scale factor is estimated based on a resultant error occurred during comparison between the estimated metric position with the estimated arbitrary position.

3. The processor-implemented method of claim 1 , wherein the estimated arbitrary scaled position differs from the estimated metric position by the scale factor.

4. A multirotor system comprising:
a memory storing instructions;
one or more communication interfaces; and
one or more hardware processors coupled to the memory via the one or more communication interfaces, wherein the one or more hardware processors are configured by the instructions to:
estimate, using a monocular camera, an arbitrary scaled position of a multirotor based on a vision SLAM (simultaneous localization and mapping) technique in an inertial frame;
input, to a multirotor dynamics-based predictor, an Euler angle estimated from the vision SLAM technique to compute an acceleration of the multirotor;
dynamically integrate the computed acceleration to estimate a metric velocity and a metric position;
compare the estimated metric position with the estimated arbitrary position from the vision SLAM technique; and
estimate a scale factor and a parameter associated with a multirotor dynamics model, wherein the parameter associated with the multirotor dynamics model is a drag coefficient.

5. The multirotor system of claim 4 , wherein the scale factor is estimated based on a resultant error occurred during comparison between the estimated metric position with the estimated arbitrary position.

6. The multirotor system of claim 4 , wherein the estimated arbitrary scaled position differs from the estimated metric position by the scale factor.

Assignees

• Tata Consultancy Services Ltd

Inventors

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

Classifications

• B64U2101/30

  for imaging, photography or videography · CPC title

• B64U10/14

  with four distinct rotor axes, e.g. quadcopters · CPC title

• G06T7/73 Primary

  using feature-based methods · CPC title

• G06T7/70 Primary

  Determining position or orientation of objects or cameras (camera calibration G06T7/80) · CPC title

• G01C21/20

  Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) · CPC title