Human-in-the-Loop Simulations by Ling Rothrock & S. Narayanan

Author:Ling Rothrock & S. Narayanan
Language: eng
Format: epub
Publisher: Springer London, London

(2) Point samplers, also referred to as attractors, are used to generate new sample points near a user-specified location in the trade space. The attractor is specified in the ATSV interface with a graphical icon that identifies an n-dimensional point in the trade space, and then new sample points are generated near the attractor—or as close as they can get to it. Unbeknownst to the user, the attractor generates new points using the differential evolution (DE) algorithm (Price et al. 2005), which assess the fitness of each new sample based on the normalized Euclidean distance to the attractor. The normalized Euclidean distance is used to avoid problems that would arise if the magnitude of the objectives varied widely. As the population evolves in DE, the samples get closer and closer to the attractor. An example is shown in Fig. 7.3 where the designer used an attractor to sample in the region where Obj1 is low and Obj3 is high, and ATSV generated additional samples as it explored the trade space in this region, filling in the “gap” that initially appeared in the plot.

Fig. 7.3Example of attractor used to explore a region in the trade space that initially had a “gap” after 100 points were generated (left); final points cluster tightly around the attractor (right)

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