Detc 2013 - 12401 Kinematic Modeling , Analysis and Conrol of Highly Reconfigurable

The Articulated Wheeled Vehicle (AWV) paradigm examines a class of wheeled vehicles where the chassis is connected via articulated chains to a set of ground-contact wheels. Activelyor passivelycontrolled articulations can help alter wheel placement with respect to chassis during locomotion, endowing the vehicle with significant reconfigurability and redundancy. The ensuing ‘leg-wheeled’ systems exploit these capabilities to realize significant advantages (improved stability, obstacle surmounting capability, enhanced robustness) over both traditional wheeledand/or legged-systems in a range of uneven-terrain locomotion applications. In our previous work, we exploited the reconfiguration capabilities of a planar AWR to achieve internal shape regulation, secondary to a trajectory-following task. In this work, we extend these capabilities to the full 3D case – in order to utilize the full potential of kinematicand actuationredundancy to enhance rough-terrain locomotion. INTRODUCTION Articulated Wheeled Vehicles (AWVs) consist of a principal vehicle-chassis connected to a set of wheels with ground contact via activelyor passively-articulated chains. The presence of the so-called ‘articulated leg-wheel’ chain endows reconfigurability, by allowing relocation of the wheel with respect to the chassis. The AWV paradigm offers immense possibilities for enhanced locomotion-performance of autonomous mobile robots while assuring the reliability of the system. For instance, the articulated-suspensions permit the vehicle to change the location of center of mass by adjusting the linkages/joints ,so as to avoid the rollover when passing the uneven terrains [1, 2]. Similarly, the vehicle can reduce its footprint to pass narrow doorways or expand the wheelbase when stability is required. The resulting class of Leg-Wheel Vehicles (as the AWVs are also called) have many potential applications (ranging from planetary exploration [3, 4], agriculture [5, 6] to military and rescue operations) due to their advantages over traditional wheeled systems. Figure 1: Schematic of Wheeled-Legged Actively Articulated Vehicles. In most applications, the wheels of an AWR are considered to be rigid discs with a single point-of-contact with the terrain. The wheel velocities are governed by a set of non-holonomic constraints, which permit rolling along the disk-plane without allowing lateral side-slip. However, potentially, these velocitylevel constraints can be violated, but is undesirable since this results in slipping and skidding. Minimization of slipping and skidding is usually desired – both from the perspective of Aliakbar Alamdari Mechanical and Aerospace Engineering, SUNY at Buffalo Buffalo, NY, 14260 [email protected] Xiaobo Zhou Mechanical and Aerospace Engineering, SUNY at Buffalo Buffalo, NY, 14260 [email protected] Venkat N. Krovi Mechanical and Aerospace Engineering, SUNY at Buffalo Buffalo, NY, 14260 [email protected]