Iterative model and controller reduction using closed-loop balancing, with application to a Compact Disc mechanism

The standard configuration for model-based control design is reformulated into a twin feedback configuration with the model and controller written in separate feedback loops. Closed-loop balanced reduction is developed in this framework. A scheme with alternating model reduction, optimal control synthesis and controller reduction steps is designed to find high-performance low-order controllers. CD-player tracking controllers with orders below 10 have been found starting from a 120th-order model.