Title: The FLEXnav precision dead-reckoning system

Authors: Lauro Ojeda, Giulio Reina, Daniel Cruz, Johann Borenstein

Addresses: The University of Michigan, Ann Arbor, MI 48109, USA. ' University of Lecce, Department of Innovation Engineering, 73100 Lecce, Italy. ' Oklahoma State University, School of Electrical and Computer Engineering, Advanced Technology Research Centre, Stillwater, OK 74078, USA. ' The University of Michigan, Ann Arbor, MI 48109, USA

Abstract: Research at the University of Michigan|s Mobile Robotics Lab aims at the development of an accurate Proprioceptive (i.e. without external references) Position Estimation (PPE) system for planetary rovers. Much like other PPE systems, ours uses an Inertial Measurement Unit (IMU) comprising three Fibre Optic Gyroscopes (FOGs) and a two-axes accelerometer, as well as odometry based on wheel encoders. Our PPE system combines data based on expert rules that implement our in-depth understanding of each sensor modality|s behaviour under different driving and environmental conditions. Since our system also uses Fuzzy Logic operations in conjunction with the Expert Rules for finer gradation, we call it Fuzzy Logic Expert navigation (FLEXnav) PPE system. The paper presents detailed experimental results obtained with our FLEXnav system integrated with our planetary rover clone, Fluffy and operating in a Mars-like environment. In addition, we compare the results of our FLEXnav system with the results obtained from a conventional Kalman Filter (KF). The paper also introduces new methods for wheel slippage detection and correction, along with comprehensive experimental results.

Keywords: fuzzy logic; inertial systems; kalman filters; redundant encoders; navigation systems; sensor fusion; slippage correction; vehicle autonomous systems; autonomous vehicles; dead-reckoning systems; position estimation; planetary rovers; expert systems; wheel slippage; space vehicles; current-compensated odometry.

DOI: 10.1504/IJVAS.2006.012206

International Journal of Vehicle Autonomous Systems, 2006 Vol.4 No.2/3/4, pp.173 - 195

Available online: 28 Jan 2007 *

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