Study on general theory of kinematics and dynamics of wheeled mobile robots.

Abstract

This paper proposes a general theory for kinematics and dynamics of wheeled mobile robots (WMRs) . This study has two features: 1) The proposed method can deal with various WMR system ranging from typical three or four-wheeled mobile robot to multi-WMR systems where multiple WMRs are connected by joints. A WMR is regarded as a planar linkage mechanism with several ends: wheels correspond to the ends. Generally, a WMR system has active joints such as steering axis, passive joints such as casters and couplers, and driven/non-driven wheels. A model of WMR system called tree structure link covering these configurations is proposed. 2) This theory deals with kinematics and dynamics of WMR including slip of wheels. WMR dynamics is derived regarding frictional force between wheels and the ground as an external force which is a function of the slip speed. When no slip is assumed in wheels, WMR's motion is expressed by kinematics. In this manner, the proposed method is applied systematically on the kinematics when slip can be neglected and the dynamics when slip exists. Furthermore, velocity input dynamics is proposed which gives the motion of WMR when the velocity commands are inputs to active joints and wheels under the condition that wheels slip.