A kinematic modeling of an amphibious spherical robot system

This paper presents a kinematic model of an amphibious spherical robot through the Denavit-Hartenberg parameters method which will allow us to describe the link to the next or the previous. Then it is going to allow us to precisely define the frames which are going to move with the links, but also allow us to connect with the base through the structure to the end-actuator. Based on the known position and orientation of the robot, a series of kinematics equations are deduced through homogeneous transformation matrix based on the kinematics model and the inverse kinematics and each joint angle can be obtained. The prototype of amphibious robot includes four water-jet propellers and eight servo motors, which can be capable of changing walking mode between water-jet system and quadruped walking system. The walking speed and direction of amphibious robot can be handled by controlling the PWM pulse duty ratio. At last, some gait experiments had been carried out on the flat floor. The results of experiments verified that the model can give important guidance to gait trajectory planning for amphibious spherical robot.