Exploração de ambientes não estruturados através de manipulador robótico implementando controlador de impedância com parâmetros variáveis

Abstract

FERNANDES. G, Unstructured environment exploration using robotic manipulator performing impedance control with variable parameters. 2013. Thesis (Master) -Sao Carlos School of Engineering, Sao Paulo University, Sao Carlos, 2013.Robotic manipulation in unstructured environments is a major challenge to the research community. Great efforts are being directed to computational vision systems development and incredible outcome has been achieved. However, the information retrieved from vision systems is often incomplete, noisy or inaccurate due to technical limitations linked to the sensors used in such systems or the positioning of the system in the environment. Furthermore, few attention is been delivered to the application of tactile information to increase the information quality about the environment. This work presents an experimental study about the environment exploration using stable contact and impedance controlled manipulators. A framework for robotic manipulation is presented and this work is positioned in such framework in a tasks and subtasks style. The detailed information about the manipulator system and the implementation is also outlined including all the control levels and communication layers is also outlined. The work describes a series of experimental tests where the manipulator performs physical contact to the environment. The impedance control parameters are than changed aiming to analyse and determine their influence into the observed results. The contact stability and the following error are used as performance indicators. Following such experimental series, four impedance control parameter change strategies are proposed, tested and analysed when performing a task of touching the environment. The results are also compared to the results obtained from the fix parameter tests. The strategies objective is improve the contact stability ensuring a accurate measurement of the environment position. The results show a real improvement of the environment position measurement towards the same measurement when using fixed impedance control parameters. Finally, results from a repeatability test for the results of environment position measurement using the best approach proposed where presented. Such results are compared from the results achieved from vision systems and show a greater performance for the tactile environment exploration approach.