Approximate decoupling and asymptotic tracking for MIMO systems

This paper studies approximate input output decoupling of nonlinear MIMO systems, for those systems which exhibit numerical ill posedness or nearly singular behavior in the exact decoupling algorithms. Although the systems considered are regular so that the exact decoupling algorithms are applicable in this case, they require inversion of an ill conditioned matrix, and yield high gain feedback solutions which may result in actuator saturation. The approximate algorithms are numerically robust, and provide solutions which do not cancel far off right half plane zeros. This latter characteristic is especially valuable when some of the far off right half plane zeros are unstable. The algorithms are inspired by and are generalizations of some examples in the flight control literature