Triangular decoupling with simultaneous disturbance rejection of general neutral time delay systems via measurement output feedback dynamic controllers

The problem of triangular decoupling with simultaneous disturbance rejection (TDDR) is studied for general neutral multi delay systems via a realizable dynamic multi delay controller feeding back measurable disturbances and the plant measurement outputs. The necessary and sufficient conditions for the problem to have a solution are established and the general analytical expression of the realizable multi delay dynamic controllers solving the problem is derived. The results are successfully applied to control an activated sludge process with varying dissolved oxygen concentration at the influent.