PLEASE NOTE THAT THE TIME FOR THIS WEEK’S SEMINAR IS DIFFERENT THAN THE USUAL. PLEASE MAKE A NOTE OF THE TIME.

What do UAVs in GPS-Denied Environments Have in Common with E. Coli Bacteria?

Professor Miroslav Krstic

Department of Mechanical and Aerospace Engineering

University of California – San Diego

Abstract:

In the absence of GPS-based position awareness (such as underwater, in buildings and caves, etc.), vehicles have to rely on solving real-time optimization problems based on other signals that might be available for measurement, such as acoustic, electomagnetic, thermal, or concentration of chemical agents. I will discuss the use of extremum seeking as a tool for navigating UAVs in GPS-denied environments. The challenge in this problem is that it violates the standard assumptions of asymptotic stability of the plant in the classical theory of extremum seeking and introduces nonholonomic kinematic constraints. Using averaging we characterize the complex almost periodic attractors that our vehicles converge to. We illustrate the utility of the approach for several applications: tracking of a moving source of diffusive contaminant, source seeking extensions to 3D and to a model of fish locomotion, experimental results with mobile robots, and a stochastic extremum seeking algorithm that conjectures what strategy might be used by bacteria (such as the flagella-actuated E. Coli) to climb food gradients. The last in this list of applications reveals the close connection between extremum seeking and the methods of "stochastic approximation."

Friday, November 2, 2007

3:00 – 4:00 p.m.

Rm. 1500 EECS