Some approximation methods for estimation and control of large scale systems

The paper presents several methods for approximate estimation and control of large scale systems, mostly based on the notions of aggregation and disaggregation. After introducing the notions for static systems in Section II, aggregation and disaggregation in dynamic systems are discussed in Section III. The condition for perfect aggregation is relaxed in two ways. One is to restrict the class of dynamic systems and the other is to restrict the state space. These two approaches are shown to provide useful approximation to the more restrictive notions of perfect aggregation and disaggregation. Section IV is devoted to improving performance measures for large scale systems.