Design, modeling and experimental evaluation of a legged, multi-vectored water-jet composite driving mechanism for an amphibious spherical robot

This paper designs a novel legged, multi-vectored water-jet composite driving mechanism (LMWCDM) for the amphibious spherical robot (ASRobot) and presents modeling and experimental evaluation of this composite driving mechanism. In order to crawl on land flexibly, the robot was designed in SolidWorks and simulated in ADAMS environment with the sit to stand motion and a crawling gait. Then the simulation results, such as driving torques, guided the selection of servomotors in different joints. In aquatic environment, the dynamic modeling of ASRobot was analyzed by synthesizing the propulsive vectors of four propellers in each workspace of legs. Simplistically, multiple underwater locomotion, such as longitudinal and lateral motion, rotary motion, sinking and floating motion and cruising motion, were proposed. Thus, using a six-axis force/torque sensor at the equivalent mass center, a force and torque measuring mechanism was developed to obtain the direct propulsive effect and validate the modeling of the driving system. To evaluate the robot design and selection of servomotors, experiments of the sit to stand motion and crawling motion were conducted. Underwater testing experiments of LMWCDM were carried out to verify the modeling of rotary motion, sinking and floating motion. Besides, underwater test of the robot prototype also proved the highly flexible and swift motion.