DETC2002/CIE-xx SUPPORTING DESIGN REFINEMENT IN MEMS DESIGN

ABSTRACT We present a framework to support design refinement during the virtual prototyping of microelectromechanical systems (MEMS). By instantiating MEMS components and connecting them to each other via ports, the designer can both configure complex systems and simulate them. We examine design refinement in the context of ease of use and representation of the virtual prototype. We propose the use of a common, formal grammar representation for the design entities in the virtual prototypeMEMS components, behavioral models and CAD models. We show that the formal grammar approach leads to easy creation of virtual prototypes. In this paper, we focus on portsthe fundamental building blocks of a virtual prototype. Ports mediate all interactions within and between aspects of the virtual prototype. For even moderately complex designs, there can be many interactions present. The representation and organization of all possible ports is important in the context of design refinement. We provide a set-theoretic formalism that defines the algebra of ports. We present a formal grammar for ports that represents a port as a set of attributes, and provide a design refinement mechanism that involves adding or modifying attributes in the port. We illustrate our framework with a MEMS example. We demonstrate that the MEMS designer can evaluate multiple design alternatives quickly and accurately with our framework. KEYWORDS Design methodology, MEMS, Simulation-based design, attribute grammars, port-based modeling, Modelica INTRODUCTION AND MOTIVATION Virtual prototyping can shorten the design cycle of MEMS products by reducing the need for expensive and timeconsuming physical prototyping. The designer can evaluate more design alternatives to obtain a better quality design. In this paper, we propose to support the process of virtual prototyping of multi-disciplinary MEMS systems. We focus our attention on those aspects of virtual prototyping that are particularly important in the context of design refinement. Specifically, we further the current state-of-the-art with respect to representation and ease of use. The system-level design process is usually top-down. The designer begins with a high-level functional description that he decomposes into sub-functions. These sub-functions are assigned to a system architecture as a configuration of components that contain both design specifications and simulation models. When further decomposition or component assignment is not desired, the designer composes the components to create a system-level configuration that is evaluated to verify the function. In this process, there are three recurring themes: composition, or combining subcomponents to create a compound component; reuse, or replacing a componen

DETC2006-99486 CONSIDERING THE INFO-GAP APPROACH TO ROBUST DECISIONS UNDER SEVERE UNCERTAINTY IN THE CONTEXT OF ENVIRONMENTALLY BENIGN DESIGN

ABSTRACT Information-Gap Decision Theory (IGDT), an approach to robust decision making under severe uncertainty, is considered in the context of a simple life cycle engineering example. IGDT offers a path to a decision in the class of problems where only a nominal estimate is available for some uncertain life cycle variable that affects performance, and where there is some unknown amount of discrepancy between that estimate and the variable's actual value. Instead of seeking maximized performance, the decision rule inherent to IGDT prefers designs with maximum immunity (info-gap robustness) to the size that the unknown discrepancy could take. This robustness aspiration is subject to a constraint of achieving better than some minimal requirement for performance. In this paper, an automotive oil filter selection design example, which involves several types of severe uncertainty, is formulated and solved using an IDGT approach. Particular attention is paid to the complexities of assessing preference for robustness to multiple severe uncertainties simultaneously. The strengths and limitations of the approach are discussed mainly in the context of environmentally benign design and manufacture

Designing Fault Tolerant Manipulators: How Many Degrees-of-Freedom?

One of the most important parameters to consider when designing a manipulator is the number of degrees-of-freedom (DOFs). This article focuses on the question: How many DOFs are necessary and sufficient for fault tolerance and how should these DOFs be distributed along the length of the manipulator? A manipulator is fault tolerant if it can complete its task even when one of its joints fails and is immobilized. The number of degrees-of-freedom needed for fault tolerance strongly depends on the knowledge available about the task. In this article, two approaches are explored. First, for the design of a General Purpose Fault Tolerant Manipulator, it is assumed that neither the exact task trajectory, nor the redundancy resolution algorithm are known a priori and that the manipulator has no joint limits. In this case, two redundant DOFs are necessary and sufficient to sustain one joint failure as is demonstrated in two design templates for spatial fault tolerant manipulators. In a second ap..

Fault tolerant task execution through global trajectory planning

Whether a task can be completed after a failure of one of the degrees-of-freedom of a redundant manipulator depends on the joint angle at which the failure takes place. It is possible to achieve fault tolerance by globally planning a trajectory that avoids unfavorable joint positions before a failure occurs. In this article, we present a trajectory planning algorithm that guarantees fault tolerance while simultaneously satisfying joint limit and obstacle avoidance requirements.

An Information Economic Approach for Model Selection in Engineering Design

ABSTRACT An important element of successful engineering design is the effective management of resources to support design decisions. Design decisions can be thought of as having two phases- INTRODUCTION Engineering design is a sequential and iterative process, consisting of the phases of product planning, clarification of task, conceptual design, embodiment design, and detail desig