Flippers-based turning analysis and implementation of a dolphin robot

Abstract

This paper studies three typical median and/or paired fin (MPF)-based turning patterns for dolphin robots including turning with only unilateral flipper, turning with braking, and pivot steering. These turning patterns are developed based on the asymmetric driving of the flippers. According to the authors' knowledge, little literature has theoretically and experimentally evaluated and compared turning maneuverability for these three turning patterns. Firstly, to accomplish the three patterns on the same robotic platform, a bevel gear set is utilized to expand the movable range of the flippers from 180° to 360°. Secondly, in terms of the slave movement control system, a Central Pattern Generator (CPG)-based controller is then built to govern the smooth locomotion of the robot. Moreover, a three-dimensional (3-D) dynamic model is derived to analytically assess the relationship between characteristic parameters and turning performance. Finally, extensive experiments including turning maneuvers and heading control are conducted to analyze the pros and cons of each pattern. This study demonstrates that these three typical turning patterns can meet different turning demands, which lay the groundwork for real-world applications.