Robust control of distributed systems with sequentially semi-separable structure

We consider the problem of designing robust controllers for uncertain spatially-varying interconnected systems distributed in one spatial dimension. Previous work has shown that the matrix structure of such systems can be exploited to allow fast analysis and design of centralized controllers with simple distributed implementations, and this paper seeks to extend these techniques to robust analysis and synthesis. Iterative algorithms are provided for robustness analysis, and controller-scaling iterations for robust design. Methods for `pulling out´ distributed uncertainties, including those in subsystem interconnections, are explained. The computational accuracy of the algorithms incorporating these techniques are demonstrated on an example.