Jesse Austin-Breneman

A Study of Student Design Team Behaviors in Complex System Design

Large-scale engineering systems require design teams to balance complex sets of considerations using a wide range of design and decision-making skills. Formal, computational approaches for optimizing complex systems offer strategies for arriving at optimal solutions in situations where system integration and design optimization are well-formulated. However, observation of design practice suggests engineers may be poorly prepared for this type of design. Four graduate student teams completed a distributed, complex system design task. Analysis of the teams’ design histories suggests three categories of suboptimal approaches: global rather than local searches, optimizing individual design parameters separately, and sequential rather than concurrent optimization strategies. Teams focused strongly on individual subsystems rather than system-level optimization, and did not use the provided system gradient indicator to understand how changes in individual subsystems impacted the overall system. This suggests the need for curriculum to teach engineering students how to appropriately integrate systems as a whole. [DOI: 10.1115/1.4007840]

DESIGN FOR MICRO-ENTERPRISE: AN APPROACH TO PRODUCT DESIGN FOR EMERGING MARKETS

Product design for emerging markets in the developing world is a rapidly growing field due to a steadily increasing market and an interest in profitably transforming consumer quality of life for this population. Economic and cultural barriers as well as other constraints present a daunting challenge for designers working in this area. This study documents current best practices and proposes a framework for future designers with a focus on creating products that foster micro-enterprise. These guidelines are drawn from existing literature and interviews with practicing designers of products for emerging markets. Four case studies are presented ranging across several product categories.

Changing Subsystem Information Strategies Using Weighted Objectives: Increasing Robustness to Biased Information Passing

Complex system design requires managing competing objectives between many subsystems. Previous field research has demonstrated that subsystem designers may use biased information passing as a negotiation tactic and thereby reach sub-optimal system-level results due to local optimization behavior. One strategy to combat the focus on local optimization is an incentive structure that promotes system-level optimization. This paper presents a new subsystem incentive structure based on Multi-disciplinary Optimization (MDO) techniques for improving robustness of the design process to such biased information passing strategies. Results from simulations of different utility functions for a test suite of multi-objective problems quantify the system robustness to biased information passing strategies. Results show that incentivizing subsystems with this new weighted structure may decrease the error resulting from biased information passing.Copyright

The autonomous underwater vehicle "Pipsqueak"

A team of freshman students was presented with the ambiguous challenge of designing an AUV (autonomous underwater vehicle) the size of a wallet. A Micro-AUV would be small enough to avoid many of the transport problems. Because of the potentially simple design of such an AUV, purchase and maintenance costs could be kept fairly low. An AUV such as Pipsqueak would likely be deployed into a lake river, where its size and the environment would allow it to investigate most efficiently. It could also be released in low current ocean areas, such as along beaches or coral reefs. In the future, we predict that as the Micro-AUVs develop and become more efficient and powerful, they might be used for deeper and more intense exploration. In this design, depth is sensed with a pressure gauge such as the Omega DPG1000. Temperature is measured with temperature sensors such as the Seabird 3Bfplus. Images of the surrounding environment would be useful in gathering scientific data. We specified using a CCD or CMOS camera that can interface with the micro controller and satisfy the volume requirements. There are large numbers of low cost, compact digital imaging cameras available today that can be readily incorporated into Pipsqueak. We propose to use the prebuilt RAMCAM from Spectronix. The dead reckoning, inertial based navigation system would be used for this vehicle. This system would have two rear facing horizontal thrusters, and one top facing vertical thruster, which will allow for turning as well as up and down motion.

Gaming the system: An agent-based model of estimation strategies and their effects on system performance

Parameter estimates in large-scale complex engineered systems affect system evolution yet can be difficult and expensive to test. Systems engineering uses analytical methods to reduce uncertainty, but a growing body of work from other disciplines indicates that cognitive heuristics also affect decision-making. Results from interviews with expert aerospace practitioners suggest that engineers bias estimation strategies. Practitioners reaffirmed known system features and posited that engineers may bias estimation methods as a negotiation and resource conservation strategy. Specifically, participants reported that some systems engineers “game the system” by biasing requirements to counteract subsystem estimation biases. An agent-based model simulation which recreates these characteristics is presented. Model results suggest that system-level estimate accuracy and uncertainty depend on subsystem behavior and are not significantly affected by systems engineers’ “gaming” strategy.