Modelling and simulation of the drivetrain of an omnidirectional mobile robot

The main contribution of this paper is to present the state-space model of an omnidirectional drivetrain (Kiwi drive) for mobile robots. Holonomy or omnidirectional movement of mobile robots is important in applications where navigation through tight space is required. Besides the already available literature regarding either dynamic or kinematic models, this paper presents the complex analysis of a mechatronic system and shows a coherent model that takes into account both the kinematics and the dynamics of a coupled electromechanical system. The model was developed based on two holonomic mobile robots: the Festo Robotino (R) and the MOGI Ethon. A simulation software developed by the authors is also presented for numerical evaluation of the model. The simulation results qualitatively confirm the model by fulfilling the empirical requirements. Both the model and the simulation software are expandable in order to improve the accuracy of the model describing actual mobile robots. Compared to other models which are based only on the kinematics of the Kiwi drivetrain, in accordance to one's technical instinct, the presented model shows that there is a cross effect between the motors of the drivetrain, where the motors affect each other.