Research On Decision Support System For Combined Fixture Design And Its Implementation

Computer-Aided fixture design based case reasoning, whose critical technology is to obtain the design rules from a great deal of cases, plays an important role in improving product design efficiency and quality. Under this background, rough set theory is introduced to design combined fixture in the thesis, and design decesion support system is studied and developed.Firstly, the character and the assembly process of combined fixture are analyzed and summarized. Then, the decision support system structure is established, the architecture and function structure are designed, and also the design process is analyzed by using this system.Decision support database of combined fixture design is established in 3D environment. Generally, part model file in 3D includes only the geometrical information. To obtain a part with all informaiton needed such as material, technical requirement, part information model based feature is established and further on the database E-R model is set up. Also, the technology for part information read-in and getting-out in Pro/Engineer is studied.According to the characteristics of the fixture product,a case retrieval strategy in decision support system is proposed based on rough set. With the aid of rough set,case attributes are reduced and the importance sequence for attributes is obtained,which is employed to build case hierarchy tree and allocate attributes weights. The rules obtained are used to guide the design of fixtures. With reduction results,case base is organized as a hierarchical structure therefore the case retrieval space is reduced and the retrieval efficiency is improved by using the index allocated.On the basis of the above-mentioned theories and technology, a prototype system of combined fixture design decision support is developed in 3D Environment-Pro/Engineer.In the end, the work of this thesis is summarized and the further research orientations are pointed out.