This three-year award supports continuation of a US-France cooperative research project involving Stephen L. Campbell, North Carolina State University, Francois Delebecque and Ramine Nikoukhah, at the French National Institute for Research in Information Science and Applied Mathematics (INRIA), Rocquencourt and Rennes, France. The objectives of this project are to develop algorithms for implicitly modeled dynamical systems and a computer environment employing symbolic, graphic and numerical software for analysis of the algorithms. The current project extends previous work on stabilization, optimization and trajectory tracking of constrained mechanical systems. The new research focuses on design, failure detection, estimation and fault isolation in control systems. These are important issues for industry. The US investigator brings to this collaboration expertise in numerical and analytical mathematics. This is complemented by French expertise in computer design, control and failure detection.