Dissertation Defense – Julia Filiberti Allen

Author: Julia Filiberti Allen

Date/Time: Monday, June 28th at 1pm

Examining Committee:
Professor Steven A. Gabriel, Chair, Dept. of Mechanical Engineering
Professor Dinesh Manocha, Dean’s Representative, Dept. of Computer Science
Professor Jin-Oh Hahn, Dept. of Mechanical Engineering
Professor Shapour Azarm, Dept. of Mechanical Engineering
Professor Jeffrey Herrmann, Dept. of Mechanical Engineering

Deep neural networks are naturally “black boxes”, offering little insight into how or why they make decisions.  These limitations diminish the adoption likelihood of such systems for important tasks and as trusted teammates.  We employ introspective techniques to abstract machine activation patterns into human-interpretable strategies and identify relationships between environmental conditions (why), strategies (how), and performance (result) on both a deep reinforcement learning two-dimensional pursuit game application and image-based deep supervised learning obstacle recognition application. Pursuit-evasion games have been studied for decades under perfect information and analytically-derived policies for static environments.  We incorporate uncertainty in a target’s position via simulated measurements and demonstrate a novel continuous deep reinforcement learning approach against speed-advantaged targets.  The resulting approach was tested under many scenarios and performance exceeded that of a baseline course-aligned strategy.  We manually observed separation of learned pursuit behaviors into strategy groups and manually hypothesized environmental conditions that affected performance.  These manual observations motivated automation and abstraction of conditions, performance and strategy relationships.  Next, we found that deep network activation patterns could be abstracted into human-interpretable strategies for two separate deep learning approaches.  We characterized machine commitment by the introduction of a novel measure and revealed significant correlations between machine commitment, strategies, environmental conditions, and task performance.  As such, we motivated online exploitation of machine behavior estimation for competency-aware intelligent systems.  And finally, we realized online prediction capabilities for conditions, strategies, and performance.  Our competency-aware machine learning approach is easily portable to new applications due to its Bayesian nonparametric foundation, wherein all inputs are compactly transformed into the same compact data representation.   In particular, image data is transformed into a probability distribution over features extracted from the data. The resulting transformation forms a common representation for comparing two images, possibly from different types of sensors.  By uncovering relationships between environmental conditions (why), machine strategies (how), & performance (result) and by giving rise to online estimation of machine competency, we increase transparency and trust in machine learning systems, contributing to the overarching explainable artificial intelligence initiative.