Title: New Results in the Design of Switched Feedback Controllers for Speaker: Keith Santarelli, Sandia National Laboratories Date/Time: Wednesday, March 31, 2010, 9:00 am Location: CSRI Building/Room 90 (Sandia NM) Brief Abstract: Feedback is an important concept that has shaped the development of modern science and engineering in innumerable ways. Within the Department of Energy, a few of the areas in which feedback plays a critical role are in the development of the power grid infrastructure on the micro- (wind turbines) and macro-scale (phase synchronization in distributed power); in basic energy sciences to control the shape and temperature of plasmas and to maintain stable operation of nuclear power plants; and in systems biology to model neural communication via spikes, and to design common engineering building blocks (e.g., clock generators and bistable latches) via biological components. In many ways, the design of modern systems is limited by our ability to design feedback controllers; the better we are at exploiting measured information to make “smart” decisions, the better performance we can achieve. The past 15 years has seen great advances in the study of hybrid systems and, in particular, switched feedback systems---systems whose dynamics switch between multiple forms of feedback control. While the study of switched systems originally stemmed from the use of relays for temperature control in the 1940s and 50s, the motivation behind current switched systems research has evolved into the following question: can we artificially introduce switching into systems design to increase performance? The tremendous amount of research that has been performed in this area illustrates that the answer is very case-specific. Indeed, it is common for many results in switched system design to carry with them a set of mathematical restrictions that constrains their applicability to broad classes of systems. In this talk, I will highlight some of my recent efforts in the design of switched feedback controllers for linear systems. After reviewing some basic trade-offs between two categories of switched system design methods---low order/phase portrait techniques vs. general order methods---I will present a new switched state feedback law that extends a control law previously developed for second order systems to linear systems of arbitrary dimension. The control law, which switches between two linear state feedback controllers to drive the state onto an n-1 dimensional hyperplane in an n-dimensional space, guarantees global exponential stability and is characterized by a simple set of conditions on eigenvalues. I will show how to design such controllers for two examples and will demonstrate their utility via an application to maximizing rate of convergence.CSRI POC: Danny Rintoul, 505-844-9592 |