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Recently, the size of raw glass has been greatly increased in the new generation Liquid Crystal Display (LCD) technology. To handle bigger and heavier glasses, it is necessary to develop a large scale LTR (LCD Transfer Robot) to support various complicated LCD fabrication processes. This adjustment will result in difficult design problems such as vibration, handling accuracy deterioration, and high stress due to heavier dynamic loads. In turn, these will result in inaccurate transfer motion and fatigue cracks.In this paper, the dynamic simulation technique is introduced to validate a baseline design and to propose new and improved designs for the best performance of heavy-scaled LCD transfer robots. The dynamic models and analysis results were verified by real experiments including strain measure test and motor power test. Using the verified simulation model, some dynamic situations such as the robot's emergency stop and free fall situation, which were not impossible to test using the real proto robot, were analyzed and predicted using the simulation model.

In this paper, a computer aided analysis method is proposed for a durability assessment in the early design stages using the Modal Stress Recovery (MSR) and the linear damage rule. From a dynamic analysis of the OHT vehicle system with some flexible bodies, modal displacement time histories of vehicle structure components are calculated. From finite element analysis of components, modal stresses are calculated. With the modal displacement time history and the modal stress of the component, the dynamic stress time history at the critical location is produced using the superposition principle. Using the linear damage rule and the cycle counting method, the fatigue life is predicted from the dynamic stress time history. The process of predicting the fatigue life using the proposed computer models in this paper may be applied to structures of various dynamic systems.