Slip Analysis for a Wheeled Mobile Manipulator

Abstract

A method is presented for slip analysis of a wheeled mobile manipulator. The said system consists of an industrial manipulator mounted on a mobile platform performing aircraft manufacturing tasks. Unlike tracked/legged mobile robots that may slip when negotiating slopes or climbing stairs, a wheeled mobile manipulator may slip resulting from the manipulator movement or the forces from the end-effector during fastening. Slip analysis is crucial to ensure pose accuracy for operation. In this study, first a universal friction constraint is used to derive the slip condition of the system. Three cases are considered, with the first case considering the reaction force in relation to the stand-off distance between the mobile manipulator and the workpiece. The second case deals with the joint speeds to investigate the effect of coupling terms including centrifugal forces and gyroscopic moments on slip. The third case deals with the joint accelerations to investigate the effect of inertia forces and moments on slip. Simulations and experiments are carried out to verify the proposed method.