The autonomous blimp project of LAAS-CNRS:: Achievements in flight control and terrain mapping

In this paper we provide a progress report of the LAAS-CNRS project of autonomous blimp robot development, in the context of field robotics. Hardware developments aimed at designing a generic and versatile experimental platform are first presented. On this base, the flight control and terrain mapping issues, which constitute the main thrust of the research work, arc presented in two parts. The first part, devoted to the automatic control study, is based on a rigorous modeling of the airship dynamics. Considering the decoupling of the lateral and longitudinal dynamics, several flight phases are identified for which appropriate control strategies are proposed. The description focuses on the lateral steady navigation. In the second part of the paper, we present work on terrain mapping with low-altitude stereovision. A simultaneous localization and map building approach based on an extended Kalman filter is depicted, with details on the identification of the various errors involved in the process. Experimental results show that positioning in the three-dimensional space with a centimeter accuracy can be achieved, thus allowing the possibility to build high-resolution digital elevation maps.