Omnidirectional mobile robots (OMRs) are capable of arbitrary motions in arbitrary directions without changing the direction of wheels since they perform 3-DOF (degree of freedoms) motions on a plane. Various omnidirectional wheels including the continuous alternate wheel (CAW) with passive rollers for OMRs have been researched. The CAW has been developed for the purpose of minimizing vibration. The CAW has alternating inner and outer rollers around the wheel which makes nearly continuous contact with the ground. The ideal CAW reduce vibration for certain; however, the real CAW fail to do so due to various errors. In this regard, more research is needed to bring vibration under acceptable tolerance. In this paper, vertical vibration characteristics of the real CAW with tolerance are researched. Simulation models of CAWs are implemented using flexible body dynamics of Recurdyn. To verify vibration characteristics of the model, simulation results are compared with experimental results from the improved CAW with five rollers set (CAW5). Vertical vibration is affected by various factors: geometry errors, the gap, the thickness of flexible body, the angular velocity, the alignment angle, the load and the elasticity of flexible body, etc. To efficiently analyze the effects of various factors, dynamic simulations are conducted using Taguchi method. As a result, it is found that the main factors which affect vibration are the angular velocity and the alignment angle followed by the geometry errors, the load, the elasticity of flexible body, the thickness of flexible body and the gap. This process can be applied to the analysis of the other omnidirectional wheels with passive rollers.
['Young Kyun Park', 'Pilgu Lee', 'Jong Kap Choi', 'Kyung Seok Byun']
Analysis of factors related to vertical vibration of continuous alternate wheels for omnidirectional mobile robots