UBC Theses and Dissertations
Design evolution of engineering systems through modeling, on-line monitoring, and evolutionary optimization Campos, Jesus Ramon
This work develops a framework of design evolution to support and automate the generation and evaluation of optimal multi-domain engineering designs. It integrates a Machine Health Monitoring System (MHMS), a Model Generation System (MGS), a Design Expert System (DES) and an Evolutionary Design Optimization System (EDOS) for aiding engineers through the redesign of an existing engineering system. First, the MHMS, while maintaining the engineering system in an operable condition by anticipating possible failures, indicates subsystems for possible design improvement. Second, the MGS which provides the capability of system modeling through the Linear Graphs approach enables representation of the current version of the system that is being designed. Third, the integration of a DES to the evolutionary framework provides automatic incorporation of expert suggestions into the system. Fourth, the EDOS automatically evolves mechatronic designs represented by Linear Graphs using Genetic Programming (GP). In addition, the Mechatronic Design Quotient has been proposed as the fitness function of the evolutionary process, as it provides an intelligent way to represent the quality of design using various design indices. Also it has proven to be a good approach to meet design constraints and do not violate the feasibility of implementation. The experimental system (Iron Butcher) is an automated industrial fish processing machine that already has a MHMS. Development of the DES is an on-going project of other researchers in our laboratory. The present thesis primarily focuses on the modeling using Linear Graph and design optimization using Genetic Programming. An algorithm which integrates GPLAB, a MATLAB toolbox for Genetic Programming, with the powerful modeling and simulation tool of Simscape is developed. Both the scheme and the design alternatives generated by the algorithm are validated using computer simulations and physical experimentation on a realistic environment. For this purpose, a state-space model of the electromechanical conveying system of the Iron Butcher is developed using Linear Graph modeling. Results show that under normal operating conditions, the response of the machine satisfactorily matches that of the state-space model. Also it is found that the new mechatronic engineering designs automatically evolved through the developed design framework successfully met the design requirements.
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