Steering Limitations for a Vehicle Pulling Passive Trailers

Motion control of articulated vehicles composed of a nonholonomic tractor and several passive trailers is a difficult underactuated problem. This paper proposes the application of steering limitations to the tractor to avoid inter unit collision during forward motion. This method can be used for systems that combine any type of on-axle and off-axle joints. We propose an algorithm to compute curvature bounds based on the analysis of steady and transient responses. These limitations can be introduced at the path tracking and path planning levels for autonomous navigation. Thus, the tractor can be controlled to follow admissible paths much in the same way as when it does not tow any trailer. The method has been validated experimentally with an off-axle two-trailer setup attached to the tracked mobile robot Auriga-alpha.