RiskEcon® Lab for Decision Metrics @ Courant Institute

Comparative Analysis of Agent-Oriented Task Assignment and Path Planning Algorithms Applied to Drone Swarms (2021): Rohith Gandhi Ganesan, Samantha Kappagoda, Giuseppe Loianno, and David K.A. Mordecai. arXiv:2101.05161

Abstract: Autonomous drone swarms are a burgeoning technology with significant applications in the field of mapping, inspection, transportation and monitoring. To complete a task, each drone has to accomplish a sub-goal within the context of the overall task at hand and navigate through the environment by avoiding collision with obstacles and with other agents in the environment. In this work, we choose the task of optimal coverage of an environment with drone swarms where the global knowledge of the goal states and its positions are known but not of the obstacles. The drones have to choose the Points of Interest (PoI) present in the environment to visit, along with the order to be visited to ensure fast coverage. We model this task in a simulation and use an agent-oriented approach to solve the problem. We evaluate different policy networks trained with reinforcement learning algorithms based on their effectiveness, i.e. time taken to map the area and efficiency, i.e. computational requirements. We couple the task assignment with path planning in an unique way for performing collision avoidance during navigation and compare a grid-based global planning algorithm, i.e. Wavefront and a gradient-based local planning algorithm, i.e. Potential Field. We also evaluate the Potential Field planning algorithm with different cost functions, propose a method to adaptively modify the velocity of the drone when using the Huber loss function to perform collision avoidance and observe its effect on the trajectory of the drones. We demonstrate our experiments in 2D and 3D simulations.

Classification of Pathological and Normal Gait: A Survey (2020): Ryan C. Saxe, Samantha Kappagoda, and David K.A. Mordecai. arXiv:2012.14465

Abstract: Gait recognition is a term commonly referred to as an identification problem within the Computer Science field. There are a variety of methods and models capable of identifying an individual based on their pattern of ambulatory locomotion. By surveying the current literature on gait recognition, this paper seeks to identify appropriate metrics, devices, and algorithms for collecting and analyzing data regarding patterns and modes of ambulatory movement across individuals. Furthermore, this survey seeks to motivate interest in a broader scope of longitudinal analysis regarding the perturbations in gait across states (i.e. physiological, emotive, and/or cognitive states). More broadly, inferences to normal versus pathological gait patterns can be attributed, based on both longitudinal and non-longitudinal forms of classification. This may indicate promising research directions and experimental designs, such as creating algorithmic metrics for the quantification of fatigue, or models for forecasting episodic disorders. Furthermore, in conjunction with other measurements of physiological and environmental conditions, pathological gait classification might be applicable to inference for syndromic surveillance of infectious disease states or cognitive impairment.

Energy Disaggregation with Semi-supervised Sparse Coding (2020): Mengheng Xue, Samantha Kappagoda, and David K.A. Mordecai. arXiv:2004.10529

Abstract: Residential smart meters have been widely installed in urban houses nationwide to provide efficient and responsive monitoring and billing for consumers. Studies have shown that providing customers with device-level usage information can lead consumers to economize significant amounts of energy, while modern smart meters can only provide informative whole-home data with low resolution. Thus, energy disaggregation research which aims to decompose the aggregated energy consumption data into its component appliances has attracted broad attention. In this paper, a discriminative disaggregation model based on sparse coding has been evaluated on large-scale household power usage dataset for energy conservation. We utilize a structured prediction model for providing discriminative sparse coding training, accordingly, maximizing the energy disaggregation performance. Designing such large scale disaggregation task is investigated analytically, and examined in the real-world smart meter dataset compared with benchmark models.

Compressing Heavy-Tailed Weight Matrices for Non-Vacuous Generalization Bounds (2021): John Y. Shin. arXiv:2105.11025

Abstract: Heavy-tailed distributions have been studied in statistics, random matrix theory, physics, and econometrics as models of correlated systems, among other domains. Further, heavy-tail distributed eigenvalues of the covariance matrix of the weight matrices in neural networks have been shown to empirically correlate with test set accuracy in several works (e.g. [1]), but a formal relationship between heavy-tail distributed parameters and generalization bounds was yet to be demonstrated. In this work, the compression framework of [2] is utilized to show that matrices with heavy-tail distributed matrix elements can be compressed, resulting in networks with sparse weight matrices. Since the parameter count has been reduced to a sum of the non-zero elements of sparse matrices, the compression framework allows us to bound the generalization gap of the resulting compressed network with a non-vacuous generalization bound. Further, the action of these matrices on a vector is discussed, and how they may relate to compression and resilient classification is analyzed.