Kinematics modeling and analyses of articulated rovers

This paper describes a general approach to the kinematics modeling and analyses of articulated rovers traversing uneven terrain. The model is derived for full 6DOF (6-degree-of-freedom) motion, enabling movements in the x,y, and z directions, as well as pitch, roll, and yaw rotations. Differential kinematics is derived for the individual wheel motions in contact with the terrain. The resulting equations of the individual wheel motions are then combined to form the composite equation for the rover motion. Three types of kinematics, i.e., navigation, actuation, and slip kinematics are identified, and the equations and application of each are discussed. The derivations are specialized to Rocky 7, a highly articulated prototype Mars rover, to illustrate the developed methods. Simulation results are provided for the motion of the Rocky 7 over several terrains, and various motion profiles are provided to explain the behavior of the rover.

I. Introduction

Articulated all-terrain rovers (ATRs) are a class of mobile robots that have sophisticated mobility systems for enabling their traversal over uneven terrain. These robots are being used increasingly in such diverse applications as planetary explorations [1], rescue operations, mine detection and demining [2], agriculture [3], military missions, inspection, and cleanup operations of hazardous waste storage sites, remote ordinance neutralization, search and recovery, security, and fire fighting.