Object-oriented design methods for human-centered engineering design

Any theory or method of design for technical systems (man-made artifacts with significant engineering components) must consider the cognitive factors of human designers. The research work aims at providing object-oriented methods to improve the engineering design process by reducing the influence of human cognitive limitations, particularly bounded rationality, interpretation, focusing and biases.;The second part of the work concerns externalization and visualization of design tasks/information addressing the concerns of human interpretation and focusing processes. An object-oriented standard modelling method assisted by set of visual modelling languages (as structured concept maps) is proposed to model technical systems, and to support externalization and visualization of design tasks/information in the design process. The contribution from this part is aimed at reducing interpretation errors, enhancing focusing and facilitating designers to communicate part of their design behaviours and design information. The externalized and visualized design tasks/information by a designer of a technical system can be seamlessly used by the designer of the computer software tool for aiding the technical system design.;Third part of the work is the design and development of object-oriented methods addressing the concerns of designer's creativity and efficiency in the design process affected by the cognitive factors. Object-oriented methods for using recurrent best design practices, also known as design patterns, are described. The methods could possibly remove a set of design biases such as affective bias and conative bias. Application of object-oriented design patterns in both descriptive and prescriptive modes is discussed. The descriptive mode helps synthesizing design solutions efficiently. The prescriptive mode could trigger design creativity in function modelling. A software prototype has been developed to demonstrate the prescriptive mode of using object-oriented design patterns. This demonstration also serves a guideline about creating a network of design patterns called design pattern language.;Fourth part of the work demonstrates a case study involving the aforementioned object-oriented methods in the three parts of work for a particular design case. A prototype software system and a set of visual modelling languages - the Unified Modelling Language (UML) and the System Modelling Language (SysML)- are used together to demonstrate the methods following the standard design procedure (for a technical system) described in the Part 1 work. It is demonstrated that the three methods applied together can have significant impact on improving design and designer's performance. The software also provides a platform for testing the effect of designer's cognitive coupling and design biases in the technical system design and can serve as an experimental tool for testing on designers as subjects. The description of the object-oriented methods can be used towards developing a computer-based design support system for the conceptual design of a technical system. The research is expected to make contributions in the area of human-centered design process of a technical system design at a conceptual stage.;The first part of the work provides the method based on the assumption of human bounded rationality and cognitive limitations. The result of the method is a multi-perspective object-oriented framework for engineering design. The multi-perspective framework simulates human cognitive coupling in design and assesses design artifact from different perspectives. The perspectives are represented by objects encapsulating the subset of laws, the subset of properties of the design artifact and the subset of properties of the design environment. It is demonstrated that the same design artifact exhibits different sets of behaviours under a set of perspectives applied by the designer. Additionally, the method addresses issues of design biases (also known as psychological inertia in the design research literature) when the designer performs function modelling from different perspectives. It is demonstrated that design biases may get introduced from any perspective, and the application of the multi-perspective method, at least to some degree, removes such design biases. A software prototype has been developed to demonstrate the application of the method to a specific design case study.;Keywords: Design methods; cognitive factors; object-orientation; externalization and visualization; design pattern and design pattern language...