| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 96 === In this thesis, the kinematic structure of numerous folding mechanisms for baby carriages, obtained from patent search of the United States and domestic patent databases, is first classified with respect to the number of wheels, seats, and folds. From which the designs of single degree of freedom six bar linkage are identified for further investigations because of their simplicity and ease of use. The motion trajectory of the points on the links of these mechanisms corresponding to the center of the front and the rear wheels of the carriage are then analyzed. It is found that the trajectories of the Watt typeⅡ mechanism possessed certain advantages over that of the other types; therefore it is selected for the study of dimensional synthesis and design optimization. A procedure for computing the dimensions of the independent design variable is developed based on the method of two-point path generation. In order to achieve higher rigidity at the unfold position and reduce the storage space requirement at the folded position, dead-center configuration of the linkage are imposed on the two end-points as additional geometric constraints. In addition, an optimization method based on genetic algorithm is presented for synthesizing the optimal link dimensions, such that the synthesized linkage would not only achieve the maximum mechanical advantage at the initial folding state to facilitate the folding action, but also retain the minimum storage space at the folded position. Finally, an acrylic prototype of the synthesized mechanism is produced to verify the presented methods
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