We study the disturbance decoupling problem for linear time invariant descriptor
systems. We give necessary and sufficient conditions for the existence of a solution
to the disturbance
decoupling problem via a proportional and/or derivative feedback that also makes
the resulting closed-loop system regular and/or of index at most one. All results
are proved constructively based on condensed forms that can be computed using orthogonal
matrix transformations , i.e., transformations that can be implemented in a numerically
stable way.
Keywords :
Descriptor system, state feedback, disturbance decoupling, orthogonal matrix transformation