POTENTIAL FIELD-BASED DECENTRALIZED CONTROL METHODS FOR NETWORK CONNECTIVITY MAINTENANCE By ZHEN KAN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy POTENTIAL FIELD-BASED DECENTRALIZED CONTROL METHODS FOR NETWORK CONNECTIVITY MAINTENANCE By Zhen Kan December 2011 Chair: Warren E. Dixon Major: Mechanical Engineering In cooperative control for a multi-agent system, agents coordinate and communicate to achieve a collective goal (e.g., flocking, consensus, or pattern formation). As agents move to perform a desired mission objective, ensuring the group remains close enough to maintain wireless communication (i.e., the group does not partition) is a great challenge in a decentralized control manner. The use of an artificial potential field is one approach that has been widely used in path planning for multi-agent systems, where an attractive potential is used to model the control objective and a repulsive potential is used to prevent collisions among the agents and obstacles. The focus of this dissertation is to develop potential field based decentralized controllers for a group of agents with limited sensing and communication capabilities to perform required mission objectives while preserving network connectivity. A two level control framework is developed in Chapter 2 for connectivity maintenance and cooperation of a multi-agent system. All agents are categorized as clusterheads or regular nodes. A high level graph is composed of all clusterheads while a low level graph is composed of all regular nodes. Artificial potential field based controllers are then developed to maintain existing links connected in both low and high level graphs and ensure that a group of agents switch from one connected configuration to another without disconnecting the underlying network in process.