Design and Control of a Four Steered Wheeled Mobile Robot

This paper presents the kinematical analysis of AZIMUT-2, a four steered wheeled mobile robot. The utilization of a new wheel concept called the AZIMUT wheel allowed us to create an innovative omnidirectional non-holonomic robot. Novelty of this wheel concept resides in the non-conventional positioning of the steering axis and the wheel axis. We propose a kinematical model based on the geometrical constraints of these wheels. The degree of mobility, steerability and maneuverability are studied. Additionally, we describe a special design implementation of the wheel mechanism to overcome a hyper-motorization issue inherent to the wheel's geometrical properties. Finally, we describe AZIMUT-2's two operational and seven locomotion modes, along with a control algorithm based on the kinematical model of the robot