A Robust Docking Strategy for a Mobile Robot Using Flow Field Divergence

Date

2008

Authors

McCarthy , Christopher
Barnes, Nick
Mahony, Robert

Journal Title

Journal ISSN

Volume Title

Publisher

Institute of Electrical and Electronics Engineers (IEEE Inc)

Abstract

We present a robust strategy for docking a mobile robot in close proximity with an upright surface using optical flow field divergence and proportional feedback control. Unlike previous approaches, we achieve this without the need for explicit segmentation of features in the image, and using complete gradient-based optical flow estimation (i.e., no affine models) in the optical flow computation. A key contribution is the development of an algorithm to compute the flow field divergence, or time-to-contact, in a manner that is robust to small rotations of the robot during ego-motion. This is done by tracking the focus of expansion of the flow field and using this to compensate for ego rotation of the image. The control law used is a simple proportional feedback, using the unfiltered flow field divergence as an input, for a dynamic vehicle model. Closed-loop stability analysis of docking under the proposed feedback is provided. Performance of the flow field divergence algorithm is demonstrated using offboard natural image sequences, and the performance of the closed-loop system is experimentally demonstrated by control of a mobile robot approaching a wall.

Description

Keywords

Keywords: Control theory; Docking; Feedback; Flow fields; Flow of fluids; Mobile robots; Optical bistability; Optical flows; Robotics; Robust control; Rotation; Affine models; Close proximity; Closed-loop stability analysis; Closed-loop systems; Control laws; Ego-m Focus of expansion (FOE); Image motion analysis; Optical flow; Robot vision systems; Time-to-contact (TTC)

Citation

Source

IEEE Transactions on Robotics

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1109/TRO.2008.926871

Restricted until

2037-12-31