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Unformatted text preview: MODELING OF AN ANTI-TILTING OUTDOOR MOBILE ROBOT Danielle Sami Nasrallah 1 Jorge Angeles 1 Hannah Michalska 2 1 Department of Mechanical Engineering, 2 Department of Electrical & Computer Engineering & Centre for Intelligent Machines McGill University, Montreal, Canada [email protected] [email protected] [email protected] ABSTRACT This paper reports on the modeling of an anti-tilting outdoor mobile robot moving on an uneven terrain that is modeled as a warped, smooth surface. The dynamics has been derived using the natural orthogonal complement, and takes into account the terrain geometry, which has not been investigated before. The Euler-Rodrigues parameters have been chosen to describe the orientation of bodies in space because of their robustness. Sim- ulation of the robot moving on distinct types of terrain are pro- vided. INTRODUCTION Mobile robots for planetary exploration are currently at- tracting increasing interest worldwide. In January 2004, the rovers Spirit and Opportunity landed successfully on Mars, and are still operating, confirming once again the feasibility of un- manned missions for planetary exploration. Other outdoor robots have been designed recently and serve for: planetary exploration ; surveying agricultural fields ; exploring volcanic environ- ments ; and general outdoor applications [4–5]. In most cases the modelling has been limited to the kinematics, without devel- opment of the associated dynamics. The dynamics of a robot moving on an uneven road profile while taking into account its geometry was reported in , but the motion is restricted to a vertical plane. This paper introduces an Anti-Tilting Outdoor Mobile Robot, ATOM, whose mission is to move across uneven terrain and un- known environments. The terrain geometry enters the dynamics of the model explicitly via the normal vectors to the ground at the contact points of the wheels with the terrain. Ours is believed to be the first development of a dynamics model of a vehicle whose motion is constrained to a warped, smooth surface. Simulations of the robot moving on distinct types of terrain: ( i ) a horizontal plane, ( ii ) an inclined plane, ( iii ) a spherical surface, and ( iv ) a general warped surface are discussed here. The novelty of the work resides in the derivation of the dynamics model that fully takes account of the terrain geometry. The modeling technique adopted here can serve as a general method in approaching the formulation of models for yet more sophisticated dynamical sys- tems on manifolds. GENERAL DESCRIPTION OF ATOM Figure 1. A SKETCH OF ATOM, THE ANTI-TILTING OUTDOOR MO- BILE ROBOT 1 Copyright c 2005 by ASME Proceedings of IDETC/CIE 2005 ASME 2005 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference September 24-28, 2005, Long Beach, California USA DETC2005-8 5098 ATOM is composed of three rigid bodies: the central body, a cylinder, carrying measurement equipment and the actuators,...
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This note was uploaded on 02/07/2011 for the course MECH 646 taught by Professor Danielnassrallah during the Fall '10 term at American University of Beirut.
- Fall '10