Attitude and Steering Control of the Long Articulated Body Mobile Robot KORYU

Abstract

Many types of mobile robots have been considered so far in the robotics community, including wheeled, crawler track, and legged robots. Another class of robots composed of many articulations/segments connected in series, such as “Snake-like robots”, “Train-like Robots” and “Multi-trailed vehicles/robots” has also been extensively studied. This configuration introduces advantageous characteristics such as high rough terrain adaptability and load capacity, among others. For instance, small articulated robots can tread through rubbles and be useful for inspection, search-and-rescue tasks, while larger and longer ones can be used for maintenance tasks and transportation of material, where normal vehicles cannot approach. Some ideas and proposal appeared in the literature, to build such big robots; many related studies concerning this configuration have been reported (Waldron, Kumar & Burkat, 1987; Commissariat A I’Energie Atomique, 1987; Burdick, Radford & Chirikjian, 1993; Tilbury, Sordalen & Bushnell, 1995; Shan and Koren, 1993; Nilsson, 1997; Migads and Kyriakopoulos, 1997). However, very few real mechanical implementations have been reported. An actual mechanical model of an “Articulated Body Mobile Robot” was introduced by Hirose & Morishima in 1988, and two mechanical models of articulated body mobile robot called KORYU (KR for short) have been developed and constructed, so far. KORYU was mainly developed for use in fire-fighting reconnaissance and inspection tasks inside nuclear reactors. However, highly terrain adaptive motions can also be achieved such as; 1) stair climbing, 2) passing over obstacles without touching them, 3) passing through meandering and narrow paths, 4) running over uneven terrain, and 5) using the body’s degrees of freedom not only for “locomotion”, but also for “manipulation”. Hirose and Morishima (1990) performed some basic experimental evaluations using the first model KR-I (a 1/3 scale model compared to the second model KR-II, shown in Fig. 1(a)-(c). Improved control strategies have been continuously studied in order to generate more energy efficient motions. This chapter addresses two fundamental control strategies that are necessary for long articulated body mobile robots such as KORYU to perform the many inherent motion capabilities cited above. The control issue can be divided in two independent tasks, namely 1) Attitude Control and 2) Steering Control. The underlying concept for the presented O pe n A cc es s D at ab as e w w w .ite ch on lin e. co m