Coursework
ECE 598 NV: Distributed Algorithms for Wired and Wireless Networks (Fall 2009)
Project Report: Failures in Hybrid Distributed Systems <pdf (slides on reference paper)>
This work set out to cover a rather broad range of material from control theory and distributed computing regarding failures, by first examining the available literature and then particularly examining the consensus problem in each community. The main result accomplishes an initial look in this direction by creating an observer in the control theoretic sense which has the capability to diagnose failures, which relies on a failure detector oracle service constructed using a history of messages that have been sent between agents in the system.
ECE 586 DL: Hybrid Systems and Control (Fall 2009)
Project Presentation: A Discrete-Time Switched System for Safe Flocking <pdf (slides)>
This project presents a discrete-time switched system that solves the safe flocking problem, which is that a group of agents starting from a safe initial condition form a roughly equi-spaced formation (flocking) while moving towards some goal, all while avoiding collisions (safety).
GE 525: Control of Complex Systems (Spring 2009)
Project Report: Simulations of Flocking Problem with Saturation and Feedback Delays
<pdf, source code>
The flocking problem has been studied for some time, and is thought to be a good way to perform distributed control for swarms of multi-agent systems, such as UAVs. The majority of these studies have not placed real-world limitations on the distributed control system that would be experienced. For example, delays and asynchrony due to wireless network transmission of state information and limited actuator operating range are infrequently analyzed. This project studies through simulation the flocking problem as a group of particles with double integrator dynamics moving from some initial condition towards a non-stationary objective, analyzing stability (convergence to a flock and convergence to the waypoint) while comparing a variety of real-world constraints: (a) with and without state (velocity) saturation, (b) with and without actuator saturation, (c) delayed state feedback, and (d) combinations of these. The future work section presents a hybrid system model being investigated for the formal analysis of these systems in the presence of another real-world constraint, failures.
ECE 528: Analysis of Nonlinear Systems (Spring 2009)
CS 524: Concurrent Programming Languages (Spring 2009)
ECE 515: Control System Theory and Design (Fall 2008)
ECE 598 SM1: Modeling and Verification of Real-Time and Hybrid Systems (Fall 2008)
Project Report: Stability Analysis of Simplex Architecture Controlled Inverted Pendulum
<pdf, source code>
Switched controllers are being used frequently for control of complex systems. However, they introduce new challenges for verification of stability, of which a great deal of work in the hybrid systems domain has been formalizing recently. This work is a stability case study of the classical inverted pendulum, in this case controlled using the Simplex architecture, a state-dependent switching controller. The main result shown uses small-gain theorems to prove stability of the system with regards to measurement delays.