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DINAME2019
DINAME2019
Orientation Control of a Pan-Tilt Camera Mechanism For Tracking a Moving Target
Submission Author:
Alessandro Zachi , RJ
Co-Authors:
Alessandro Zachi, Daniela Azevedo, Antonio C. Leite, Josiel Gouvêa, Cristiano Carvalho
Presenter: Alessandro Zachi
doi://10.26678/ABCM.DINAME2019.DIN2019-0121
Abstract
In this work, an algorithm based on visual feedback is developed to control the orientation of a pan-tilt camera. The scheme is applied to a servo system consisting of a single fixed-base monocular camera. The key idea is to set the camera orientation automatically, commanding the pan and tilt angles of its base so that a desired (fixed) image point remains focused on the projection of a moving target of interest. The approach focuses attention on designing control laws to drive the DC motors that perform the adequate pan and tilt movements to track the target on-line. To deal with the parametric uncertainties that may occur in the dynamical equations of the system camera-motors, a modified version of the Active Disturbance Rejection Control Method- ADRC is developed. The proposed methodology is used in the mathematical formulation of an output feedback controller whose closed-loop stability analysis can be performed using classical formalism. From a theoretical point of view, the efficiency of the control algorithm is guaranteed by the demonstration of local stability properties and the asymptotic convergence of position errors to a small residual set around zero. In addition, it is demonstrated that the proposed control law does not require the measurements of the pan and tilt angles of the motors and does not depend on the exact knowledge of the intrinsic parameters of the camera-motors mechanism. From a practical point of view, it is believed that the proposed scheme has an attractive advantage for the experimental setup since the implementation of the algorithm does not require neither additional sensors nor the calibration of the camera parameters. The efficiency of the closed-loop visual servoing algorithm is verified through computational simulations.
Keywords
visual servoing, Pan-Tilt camera, Orientation control, ADRC method
