Discontinuous zigzag gait planning of a quadruped walking robot with a waist-joint

A method of discontinuous zigzag gait planning is presented for a quadruped walking robot with a waist-joint on even terrain. In contrast to a single rigid-body walking robot, the waist-joint that connects the rear and front parts of the body is used to move the body from side to side, thereby guaranteeing stable walking. First, the characteristics of a waist-jointed walking robot are described, followed by kinematic modeling of the robot with new parameters, such as the waist-joint position, and rotation angle of the front and rear body. An equation is then derived to describe the relation between the center of gravity of the robot and the waist-joint, and systematically analyze the gait. Thereafter, a method of discontinuous zigzag gait planning is proposed for a quadruped walking robot with a waist-joint. Finally, the superiority of a waist-jointed walking robot is demonstrated based on its extended stride and the increment of the gait stability margin. For a detailed description, the gait planning is simulated step by step. As a result, the proposed gait planning was found to create a walking posture similar to that of an animal. The proposed gait planning is also demonstrated using an experimental walking robot with a waist-joint, called ELIRO-II.