Structure Design and Dynamical Modelling of a Spherical Robot Driven by Omnidirectional Wheels

In this paper, our work focused on designing a novel spherical robot driven by omnidirectional wheels and developing an under-actuated dynamical model for the system. The robot consists of four parts: the running spherical shell (1P), the supporting platform (1P), the driving omnidirectional wheels (3P) and the bearing ball wheels (3P). Considering the noholonomic constrains aroused from the contacts of the shell with the omnidirectional wheels, and the shell with ground, we derived a dynamical model for the system by Chaplygin dynamics. The model illustrated that the robot was an under-actuated system of six DOF (degree of freedom) and three driving-torque inputs. finally, we performed an inverse dynamics simulations of S-curve trajectory to show the effectiveness of the model.