Title: An immersion and invariance-based speed observer for visual servoing

Authors: Bo Yang; Hui-Guang Li; Xiao-Peng Sha; Nuan Shao

Addresses: Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China. ' Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China. ' Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China. ' Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China

Abstract: In visual servoing, joint speeds of the robot are required for feedback control. However, most robots are not equipped with the angular velocity sensors. This paper deals with a speed observer for a visual servoing system based on the immersion and invariance (I&I) technique. The visual servoing system, a new binocular stereo visual model (BSVM) is considered, which 3-dimension image information is obtained directly, that we need not to estimate the depth information. We have considered the visual servoing system that contained the non-linear robot dynamics, an image-based controller and a speed observer. It will make the stabilisation analysis of the closed-loop system very difficult. A controller is designed so that the robot visual servoing system is transformed into a port-controlled Hamiltonian (PCH) system. It will simplify the stabilisation analysis. For the PCH system, firstly, a speed observer is designed by the technical of I&I. Secondly, a visual servo controller is designed to satisfy the visual servoing performance. Simulation experiments illustrate the theory and show the effectiveness of the proposed designs.

Keywords: speed observer; Hamiltonian; robot manipulators; immersion; invariance; robot visual servoing; joint speeds; robot joints; feedback control; robot control; binocular stereo vision; robot dynamics; image based controllers; controller design; servo control; simulation.

DOI: 10.1504/IJMIC.2012.049688

International Journal of Modelling, Identification and Control, 2012 Vol.17 No.3, pp.212 - 222

Published online: 17 Dec 2014 *

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