9309523 Teel The field of nonlinear control continues to see exciting breakthroughs yet such developments often have a difficult time finding their way into the realm of practical implementation. The objective of this research program is to elaborate on the theoretical power of nonlinear control while at the same time providing a more solid foundation for the use of nonlinear control tools in engineering applications. The former will be accomplished by furthering results on inherently nonlinear control systems and control solutions. The latter will be achieved by concurrently putting a premium on developing algorithms that are robust and efficient. This research will include further investigation employing time- varying feedback, saturation, hysteresis, dead-zones and sublinear feedback. Previous work with saturation functions has already proved very fruitful for globally stabilizing critically unstable linear systems with inputs subject to magnitude constraints, as well as for stabilizing challenging nonlinear systems. Important progress has also been made in the development of time-varying feedback for the stabilization of nonholonomic systems. This time the emphasis will be placed in robustness and practicality by focusing on output feedback solutions and by allowing for uncertainty and unmodeled dynamics. A premium will also be placed on performance, employing computer simulation at this stage to evaluate the design algorithms. ***
