Dynamics Modeling of A Three-Drive Eccentric Pendulum Spherical Robot

This paper presents the dynamic equations of a three-drive eccentric pendulum spherical robot. The robot has two motors to drive the eccentric pendulum to swing around the long axis and the short axis respectively, and the third motor can drive the pendulum to rotate around the axis vertical to the ground, so that the robot can roll according to the principle of center of mass offset and conservation of angular momentum. Compared with other mechanisms, the three-drive has stronger fault-tolerant performance, and the robot can still achieve omnidirectional rolling if any joint fails, with higher reliability. At the same time, the introduced dynamic recursion method from the inside to the spherical shell has good scalability and can be used for the robot dynamic recursion based on the sphere. The presented dynamic model was verified by simulation.