Digital implementation of a mixed objectives MIMO controller for a compact disc player using a multiprocessor system

Describes the implementation of an LMI-based mixed objectives MIMO controller on a digital multiprocessor system for the control of a CD player mechanism. In order to cope with the constraints imposed by real-time applications, several engineering choices have to be made. Firstly, model reduction has to be performed on the controller obtained from the LMI solver. Secondly, an appropriate choice of the sampling rate to discretize the continuous time controller has to be made. Both these steps, controller order reduction and discretization, contribute to a performance degradation. This is particularly critical in a mixed objectives design since, ideally, one would like to keep this degradation within acceptable bounds uniformly over all considered channels and performance indices. Thirdly, we have to choose a computation scheme for the controller that exploits as much as possible the parallelism of the processors. Our implementation allows relatively high controller orders and sampling rates with a computational delay that does not depend on the specific controller order. Finally, we present experimental results showing that the mixed objectives controller exhibits significant performance improvements if compared to a single-objective ℋ_∞ design