Actively coordinated wheeled vehicle systems /

Abstract

ABSTR A C T This research effort is directed towards actively coordinated wheeled vehicle systems, a class o f advanced mobility systems that are suited for operation on unstructured terrain.Actively coordinated vehicles refer to vehicles that possess the ability to influence the contact forces at the vehicle-terrain contact locations, and the ability to vary their configuration to accommodate to terrain obstacles.Unlike legged locomotion systems, wheeled systems do not possess omni-directional motion capability.This leads to nonholonomic kinematic constraints that cause unique complications in wheeled systems.This dissertation addresses the issues o f force planning, motion planning, dynamic simulation, and autonomous navigation of actively coordinated w heeled systems operating on uneven terrain.The work also includes design, fabrication, and preliminary experimental testing o f the W heeled A ctively Articulated V ehicle (W AAV) in a laboratory environment.Even though this research effort is primarily directed towards actively coordinated wheeled vehicles, some results obtained during the course o f this work are also applicable to other actively coordinated mechanisms.Inertial sensing is used in robotic systems to obtain orientation and the angular rates o f the vehicle body for control purposes, and to obtain absolute vehicle position on the terrain for the purpose o f guidance.In the absence of accurate maps o f the environment, inertial sensing systems can possess significant drift errors.In this work, a drift-free star sensor based navigation scheme is investigated, and its relative advantages and disadvantages as compared to existing systems are studied.