Design and kinematic analysis of an amphibious spherical robot

Nowadays, microrobots are being widely researched in order to deal with complicated missions in limited spaces. But important abilities such as locomotion velocity and enduring time are usually sacrificed in order to realize compact sizes. To solve these problems, we proposed a mother-son multi-robots cooperation system, named GSL system, which included several microrobots as son robots, and a novel designed amphibious spherical robot as the mother robot. The mother robot, which was called GSLMom robot, was designed to be able to carry microrobots and provide power supply for them. This paper will mainly focus on the structure and mechanism of the GSLMom robot. The GSLMom robot, which was designed as an amphibious spherical one, was shaped by a fixed hemisphere hull, and two openable quarter ball hulls. The robot was equipped with a 4 unit locomotion system, and each unit consists of a water jet propeller and two servo motors. Each servo motor could rotate 90° in horizontal or vertical direction respectively. When moving in water, servo motors controlled the directions of water jet propellers and the 4 propellers worked to actuate the robot. With this mechanism, the robot could realize moving forward, backward, rotating, floating and sinking motion in water. In the ground situation, propellers were used as legs, and servo motors actuated these legs to realize walking mechanism, so that the robot could realize moving forward, backward, and rotating motions on the ground. After discussed structures, actuating strategies were proposed for the robot. And kinematic models of the robot were also built.