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Chapter 18
Unicycle-like Robots with Eye-in-Hand
Monocular Cameras: From PBVS towards IBVS
Daniele Fontanelli, Paolo Salaris, Felipe A.W. Belo, and Antonio Bicchi
Abstract.
This chapter presents an introduction to current research devoted to the
visual servoing problem of guiding differentially driven robots, more specifically,
unicycle-like vehicles, taking into consideration limited field of view (FOV) con-
straints. The goal is to carry out accurate servoing of the vehicle to a desired pos-
ture using only feedback from an on-board camera. First, a position based scheme
is proposed, adopting a hybrid control law to cope with limited camera aperture.
This scheme relies on a localization method based on extended Kalman filter (EKF)
technique that takes into account the robot motion model and odometric data. To
increase the potentiality of the visual servoing scheme with respect to existing so-
lutions, which achieve similar goals locally (
i.e.
, when the desired and actual cam-
era views are sufficiently similar), the proposed method visually navigate the robot
through an extended visual map before eventually reaching the desired goal. The
map construction is part of the approach proposed here, which is then called vi-
sual simultaneous localization and mapping (VSLAM) for servoing. Position based
scheme accuracy are intrinsically related to the effectiveness of the localization pro-
cess, which is related to the estimation of 3D information on both the robot and the
environment. A shortcut overcoming the estimation process uses visual information
directly in the image domain. In this spirit, an image based scheme is presented. The
controller is devoted to constantly track desired image feature trajectories. Such tra-
jectories represent optimal (shortest) paths for the vehicle from the 3D initial posi-
tion towards the desired one. Optimal trajectories satisfies the additional constraint
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