Kinematic Analysis of a Omnidirectional Robot with the Active-caster Robotic Drive with a Ball Transmission

This paper presents a holonomic omnidirectional mobile robot using an active-caster robotic drive with a single-layer ball transmission (ACROBAT-S). This robot can move and turn indipendently in 3DOF and the number of motors is not redundant. The proposed mechanism includes a unique drive train with a ball-roller traction system to drive the active-caster omnidirectional wheel system. The proposed ball transmission contributes to simplify a control system since it needs no angle sensor and complicated calculations for cooperative motor control. To realize this concept, we analyze the kinematics of the proposed mechanism. The results show that the robot can achieve holonomic omnidirectional movement with simple control of three motors. Finally, we design this robot and show its appearance.