Simple integral-action controllers for SISO and MIMO systems

A simple low order controller synthesis is developed for certain classes of linear, time-invariant, multi-input multi-output plants. The order of these controllers depends on the number of right-half plane plant poles rather than the order of the plant to be stabilized. Furthermore, the controller´s poles and zeros are all in the stable region with the exception of one pole at the origin for the integral-action design requirement. The integral-action in the controller achieves asymptotic tracking of step input references with zero steady-state error. The freedom available in the design parameters may be used for additional performance objectives although the only goal here is stabilization and tracking of constant references.