Kristina Shea

Computer-Based Design Synthesis Research: An Overview

One of the hallmarks of engineering design is the design synthesis phase where the creativity of the designer most prominently comes into play as solutions are generated to meet underlying needs. Over the past decades, methodologies for generating concepts and design solutions have matured to the point that computation-based synthesis provides a means to explore a wider variety of solutions and take over more tedious design tasks. This paper reviews advances in function-based, grammar-based, and analogy-based synthesis approaches and their contributions to computational design synthesis research in the last decade.

A Shape Annealing Approach to Optimal Truss Design With Dynamic Grouping of Members

A shape annealing approach to truss topology design is presented that considers the tradeoff between the mass of the structure and the grouping of members, where all members of a group are given the same size. The problem of optimal grouping involves finding a structural design with an optimal number of groups and the optimal sizes for each group. In this paper cross-sectional area is considered as the measure of group size. Designs incorporating multiple members with the same cross-sectional area are advantageous when considering the cost of purchasing and fabricating materials. The shape annealing method is used as an approach to solve this problem by incorporating a method for dynamic grouping of members based on cross-sectional area that creates a tradeoff between mass and the number of groups through a weighted objective function that includes a group penalty function. This method is demonstrated on transmission tower and general truss problems.

The Cognitive Factory

The automation of processes and production steps is one of the key factors for a cost effective production. Fully automated production systems can reach lead times and quality levels exceeding by far those of human workers. These systems are widely spread in industries of mass production where the efforts needed for setup and programming are amortized by the large number of manufactured products. In the production of prototypes or small lot sizes, however, human workers with their problem solving abilities, dexterity and cognitive capabilities are still the single way to provide the required flexibility, adaptability and reliability. The reason is that humans have brains, computational mechanisms that are capable of acting competently under uncertainty, reliably handling unpredicted events and situations and quickly adapting to changing tasks, capabilities, and environments. The realization of comparable cognitive capabilities in technical systems, therefore, bears an immense potential for the creation of industrial automation systems that are able to overcome today’s boundaries. This chapter presents a new paradigm of production engineering research and outlines the way to reach the Cognitive Factory, where machines and processes are equipped with cognitive capabilities in order to allow them to assess and increase their scope of operation autonomously.

The design of novel roof trusses with shape annealing: assessing the ability of a computational method in aiding structural designers with varying design intent

A study of roof truss designs conceived by architects and civil engineers as well as those generated with shape annealing, a computational design method for structural configuration, is presented. The purpose of this study is to assess the capabilities of shape annealing in (1) meeting the needs of designers with varying intent, and (2) presenting spatially intriguing, yet functional, structures that expand the range of designs considered in the conceptual design stage. An advantage of shape annealing for conceptual design is unbiased, directed exploration of the design space. The conclusion of this study is that shape annealing generates alternatives that appeal to designers with different purposes while providing insight into relations between structural form and function.

Artificial Cognition in Production Systems

Todays manufacturing and assembly systems have to be flexible to adapt quickly to an increasing number and variety of products, and changing market volumes. To manage these dynamics, several production concepts (e.g., flexible, reconfigurable, changeable or autonomous manufacturing and assembly systems) were proposed and partly realized in the past years. This paper presents the general principles of autonomy and the proposed concepts, methods and technologies to realize cognitive planning, cognitive control and cognitive operation of production systems. Starting with an introduction on the historical context of different paradigms of production (e.g., evolution of production and planning systems), different approaches for the design, planning, and operation of production systems are lined out and future trends towards fully autonomous components of an production system as well as autonomous parts and products are discussed. In flexible production systems with manual and automatic assembly tasks, human-robot cooperation is an opportunity for an ergonomic and economic manufacturing system especially for low lot sizes. The state-of-the-art and a cognitive approach in this area are outlined. Furthermore, introducing self-optimizing and self-learning control systems is a crucial factor for cognitive systems. This principles are demonstrated by a quality assurance and process control in laser welding that is used to perform improved quality monitoring. Finally, as the integration of human workers into the workflow of a production system is of the highest priority for an efficient production, worker guidance systems for manual assembly with environmentally and situationally dependent triggered paths on state-based graphs are described in this paper.

Languages and semantics of grammatical discrete structures

Applying grammatical formalisms to engineering problems requires consideration of spatial, functional, and behavioral design attributes. This paper explores structural design languages and semantics for the generation of feasible and purposeful discrete structures. In an application of shape annealing, a combination of grammatical design generation and search, to the generation of discrete structures, rule syntax, and semantics are used to model desired relations between structural form and function as well as control design generation. Explicit domain knowledge is placed within the grammar through rule and syntax formulation, resulting in the generation of only forms that make functional sense and adhere to preferred visual styles. Design interpretation, or semantics, is then used to select forms that meet functional and visual goals. The distinction between syntax used in grammar rules to explicitly drive geometric design and semantics used in design interpretation to implicitly guide geometric form is shown. Overall, the designs presented show the validity of applying a grammatical formalism to an engineering design problem and illustrate a range of possibilities for modeling functional and visual design criteria.

Developing Intelligent Tensegrity Structures with Stochastic Search

Reference IMAC-CONF-2002-021doi:10.1016/S1474-0346(02)00003-4View record in Web of Science Record created on 2007-08-14, modified on 2016-08-08

A Computational Product Model for Conceptual Design Using SysML

The importance of the concept development phase in product development is contradictory to the level and amount of current computer-based support for it, especially with regards to mechanical design. Paper-based methods for conceptual design offer a far greater level of maturity and familiarity than current computational methods. Engineers usually work with software designed to address only a single stage of the concept design phase, such as requirements management tools. Integration with software covering other stages, e.g. functional modeling, is generally poor. Using the requirements for concept models outlined in the VDI 2221 guideline for systematic product development as a starting point, the authors propose an integrated product model constructed using the Systems Modeling Language (SysML) that moves beyond geometry to integrate all necessary aspects for conceptual design. These include requirements, functions and function structures, working principles and their structures as well as physical effects. In order to explore the applicability of SysML for mechanical design, a case study on the design of a passenger car’s luggage compartment cover is presented. The case study shows that many different SysML diagram types are suitable for formal modeling in mechanical concept design, though they were originally defined for software and control system development. It is then proposed that the creation and use of libraries defining generic as well as more complicated templates raises efficiency in modeling. The use of diagrams and their semantics for conceptual modeling make SysML a strong candidate for integrated product modeling of mechanical as well as mechatronic systems.Copyright

Design-to-fabrication automation for the cognitive machine shop

To meet the rising demands for pure customization of products, new approaches for automated fabrication of customized part geometry are needed, on both the software and hardware side, that balance flexibility, robustness and efficiency. This is a great challenge since today it requires significant human expertise supported, only partially, by computer-aided approaches. This paper introduces a new approach and framework for an autonomous design-to-fabrication system that integrates cognitive capabilities, such as reasoning from knowledge models and autonomous planning, and embeds these in the machines themselves to automatically fabricate customized parts. The framework integrates into a common process automatic workpiece selection using an ontology, generative CNC machining planning using shape grammars and automated fixture design, based on a novel flexible fixture device hardware. Initial results are given for the machining planning approach applied to 2.5D parts with a defined approach direction and the prototyped fixture device is presented. The advantages and potential of the framework stem mainly from applying the principles of cognitive technical systems to a fabrication system to develop an integrated and on-line approach. The methods are developed specifically for use on the machine shop floor to take advantage of the possibility to update and extend knowledge models to reflect current fabrication capabilities and to adapt to changes in the environment and re-plan during operation. Finally, future directions, including integrating on-line perception and learning, are discussed, which are required to create a truly flexible and cognitive fabrication system.

Multicriteria optimization of paneled building envelopes using ant colony optimization

Definition of building envelopes is guided by a large number of influences including structural, aesthetic, lighting, energy and acoustic considerations. There is a need to increase design understanding of the tradeoffs involved to create optimized building envelope designs considering multiple viewpoints. This paper presents a proof-of-concept computational design and optimization tool aimed at facilitating the design of optimized panelized building envelopes for lighting performance and cost criteria. A multicriteria ant colony optimization (MACO) method using Pareto filtering is applied. The software Radiance is used to calculate lighting performance. Initial results are presented for a benchmark and project-motivated scenario, a media center in Paris, and show that the method is capable of generating Pareto optimal design archives for up to 11 independent performance criteria. A preliminary GUI for visualizing the Pareto design archives and selecting designs is shown. The results illustrate that for desired values of lighting performance in different internal spaces, there is often a range of possible panel configurations and costs.