Title: Dynamic analysis of flexible legged vehicles using the finite element method

Authors: E.M. Bakr, I. Gastouniotis, A.A. Shabana

Addresses: Department of Mechanical Engineering, University of Illinois at Chicago, P.O. Box 4348, Chicago, Illinois 60680, USA. ' Department of Mechanical Engineering, University of Illinois at Chicago, P.O. Box 4348, Chicago, Illinois 60680, USA. ' Department of Mechanical Engineering, University of Illinois at Chicago, P.O. Box 4348, Chicago, Illinois 60680, USA

Abstract: A method for the dynamic analysis of multibody walking vehicles that consist of interconnnected rigid and flexible components is presented. Flexible components in the legged vehicle are discretized using the finite element method. Mechanical joints between different components in the system as well as specified trajectories performed by the legs are formulated using a set of nonlinear algebraic constraint equations. The dependent coordinates are written in terms of the system degrees of freedom by partitioning the constraint Jacobian matrix. The system differential equations associated with the independent coordinates are identified and written in the state space formulation. The formulation presented is exemplified using a three-legged walking vehicle that consists of either interconnected rigid and flexible components. A simple computer-controlled strategy is developed to account for the change in the kinematic structure due to the leg-ground interaction and to ensure a precise and stable positioning of the feet. Numerical experimentations indicate that the effect of flexibility on the overall dynamic behaviour of the vehicle as well as on the system reaction forces is significant.

Keywords: dynamic analysis; finite element method; FEM; flexible legged vehicles; walking vehicles; legged locomotion; kinematic; walking robots.

DOI: 10.1504/IJVD.1989.061559

International Journal of Vehicle Design, 1989 Vol.10 No.1, pp.1 - 15

Published online: 26 May 2014 *

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