Design of robust controllers for a 3-input 3-output supersonic aircraft powerplant using ICD

Controllers are designed for a 3-input 3-output supersonic aircraft powerplant using individual channel design (ICD). The system to be controlled is initially checked for decoupling for design purposes using a decoupling theorem. One channel of the system is very weakly coupled; hence the 3-input 3-output multivariable design task reduces to a SISO design problem and a 2-input 2-output design problem. The possibility of such a decoupling for design purposes is indicated by multivariable structure functions Γ_i. The cross-coupling of the closed-loop system is very unbalanced but is rectified using a simple precompensator