Seminar Details
2012-11-13 (14.00) : Dissipative Systems Theory and Distributed Control of Interconnected Processes
At Euler building
Organized by Mathematical Engineering
Speaker :
Nicolas Hudon (UCL)
Abstract :
In recent years, as energy and mass integration of chemical processes have been introduced from a process design perspective, many researchers recognized the need for new methods to analyze the dynamics and to design controllers for interconnected chemical process units. On the other hand, the emergence of cheap and reliable communication networks gave a new perspective for the design of distributed controllers, using all information available to increase interconnected processes performance. However, for chemical processes described by nonlinear dynamics, the design and coordination of distributed controllers is still an open problem.
In this talk, we consider an approach to analyze and control interconnected chemical processes. Using a general representation, we use dissipative systems theory as a tool for both the analysis of the global process and for the design of decentralized state and output feedback controllers. The principal objective of the proposed approach is to design distributed feedback controllers to achieve plant-wide stability for a given interconnection structure. At a plant-wide level, extensions of classical results on the stability of large-scale interconnected systems lead to input-output dissipativity constraints for each subsystems, encoded as supply rates from input to output interconnecting ports. Then, for each subsystem, a parameterized nonlinear feedback controller is designed using nonlinear dissipative inequalities to ensure that the aforementioned dissipativity constraints are met in closed-loop. The key advantage of using parameterized controller is the possibility to balance local and global objectives.
This talk also briefly covers new results on the construction of storage functions for control affine systems, as a generalization of physics-based approaches to dissipative systems theory. In particular, it is shown, under a convexity condition, that an approximate storage function candidate can be constructed using a decomposition of the drift vector field. Finally, we discuss some dynamic feedback and robust design extensions obtained recently along those lines. Some open problems around the themes of optimization over networks and analysis of time-varying interconnection structures are discussed within that context.