Computation of equivalent size for tractor-trailer wheeled mobile robot

Equivalent size (ES) of tractor-trailer wheeled mobile robot (TTWMR) is used to enlarge obstacles in static workspace so as to plan path effectively for this kind of robot. We analysed motion characteristics of the trailers when the tractor moved along a circular path, and considered the deviation between the paths followed by the tractor and the trailers respectively. A new method for computing ES was proposed by means of the relation between the steady deviation and the transient one. Then how to use ES in path planning and mechanism constructing was discussed. Finally, a simulation example of our super-hero tractor-trailer robot was presented. The experiment results show the validity of our method.

I. Introduction

Tractor-trailer wheeled mobile robot is a kind of nonholonomic and nonlinear system, which consists of a tractor and multiple trailers as shown in Fig. 1. It can be categorized into standard link and nonstandard link according to the position of link point. The standard form is defined that the link point lies on the midpoint on rear axle of the former body, and the nonstandard one is that the link point lies on the intersection of two connecting rods. In Fig. 1, the bodies are linked with nonstandard form, while the system becomes standard form. Fig. 1 The tractor-trailer mobile robot with N trailers