REGULAR MOTION OF A TUBE-CRAWLING ROBOT IN A CURVED TUBE*

ABSTRACT The motion of an eight-legged tube-crawling robot through a curved (toroidal) tube is investigated in terms of kinematics. A class of regular gaits implementing such a motion is defined. In these gaits, the center of mass of the robot body moves by the same distance during each step, and, at the beginning and the end of each step, the center of mass of the robot body lies on the axis of the tube and, moreover, the axis of the robot is tangential to that of the tube. Each step consists of two half-steps. During each half-step the robot body performs a plane-parallel motion in the plane where the feet of the supporting legs lie. The parameters of the gait are calculated, and some qualitative features of the motion of the robot are analyzed. Computer simulation results are presented. The analysis of the motion of the robot in a toroidal tube is important for planning and control of the passage of the robot through turns of a pipeline. *Communicated by W. Book.