Generalized normal forms and disturbance rejection: a symbolic approach

The paper employs a symbolic approach, making use of the computer algebra system MAPLE and the NONCON package, to compute (1) a generalized normal form for systems without a well-defined relative degree using the zero dynamics algorithm and (2) a state feedback that achieves disturbance rejection or decoupling with an implementation of an algorithm for the maximal controlled invariant distribution. A few examples illustrate the power of the approach, but only for rather simple problems. Due to the complexity of the (implementation of the) algorithms it seems unlikely that large scale problems are efficiently solvable symbolically.