Design and analysis of a deployable tetrahedron-based mobile robot constructed by Sarrus linkages

Abstract

In this paper, a novel deployable tetrahedron-based mobile robot constructed by Sarrus linkages with eight degrees of freedom (DOFs) is proposed. The robot is composed of a core tetrahedron and four branch tetrahedrons with a total of eight nodes and 18 planar RRR chains (R denotes revolute joint), and each node and any two branch chains connected to it is a Sarrus linkage. Referring to the kinematics of the general-type Sarrus linkage, the kinematics of the robot is analyzed in detail. Based on it, two non-impact rolling gaits of rolling in Direction I/II and rolling in Direction III are discussed, then the continuous non-impact rolling locomotion is elaborated. Besides, two folding modes of folding as an umbrella shape and deploying in radially reciprocating motion are developed. Finally, a prototype is manufactured, the rolling experiments indicate that the robot can roll in any direction for arbitrary distance with the trajectory of a series of triangles, and the two additional folding modes increase the convenience of storage and transportation of the robot.