Control of a Five-axle, Three-steering Coupled-vehicle System and its Experimental Verification

This paper presents a new type of coupled-vehicle system: a five-axle, three-steering coupled-vehicle system consisting of two vehicles which are car-like mobile robots, two carriers, and a steering system, and presents its path-following feedback control method. We first show that, by assuming virtual mechanical elements, it is possible to convert the kinematical equation of the coupled-vehicle system into a three-chain, single-generator chained form in a new coordinate system where an arbitrary path whose curvature is two times differentiable is one coordinate axis and a straight line perpendicularly intersecting the tangent of the path is the other coordinate axis. Based on the chained form, we secondly derive the path-following feedback control method which enables the orientations of the two carriers relative to the tangent of the path to be controllable. By the feedback control method, it is possible to form the two carriers into a straight-bed carrier configuration or a V-bed carrier configuration and to cause them to maintain such configurations while performing a path-following operation thus enabling the two carriers to be configured in accordance with shapes of objects to be transported. The validity of the mechanical design of the coupled-vehicle system and its path-following feedback control method has been verified experimentally.