Title: Modelling and design of tracked mobile climbing robots on non-planar surfaces

Authors: Stephen L. Canfield; Padmanabhan Kumar; Joshua E. Qualls

Addresses: Department of Mechanical Engineering, Brown Hall 224, 115 W. 10th Street, Cookeville, TN 38505, USA ' Department of Mechanical Engineering, Brown Hall 224, 115 W. 10th Street, Cookeville, TN 38505, USA ' Department of Mechanical Engineering, Brown Hall 224, 115 W. 10th Street, Cookeville, TN 38505, USA

Abstract: This paper presents an analysis of a tracked-based skid steer mobile robot following a defined path on a class of non-planar surfaces. The analysis will define a method to approximate the position and orientation of each track on a climbing surface in a manner that ensures opposing, symmetric components of the robot are geometrically even in their positioning relative to the base surface. The analysis will assume the robot chassis travels along the path with an orientation defined by the vectors tangent to the path and normal to the climbing surface, and that the centerline distance and longitudinal displacements between the tracks units are fixed. It will be shown that for general paths, three rotational degrees of freedom are required between the tracks to maintain line contact with the surface along the length of the track. This implies that the tracks do not remain parallel while following paths on non-planar surfaces. It will further be shown that relative lateral slipping between the left and right tracks result when traversing non-planar surfaces. Two subsets of paths are shown to require one rotational degree of freedom only and avoid lateral slipping. The model will then be used to define the required relative motion between the tracks which can be used to design a kinematic arrangement for connecting track modules to a central chassis in a manner to minimise slip and maximise surface contact when climbing on non-planar surfaces.

Keywords: climbing; mobile robot; non-planar; skid steer; tracks.

DOI: 10.1504/IJMRS.2017.087348

International Journal of Mechanisms and Robotic Systems, 2017 Vol.4 No.1, pp.24 - 42

Received: 17 Jul 2016
Accepted: 14 Mar 2017
Published online: 13 Oct 2017 *