Stabilization of pure unstable delay systems by the mirror mapping technique

In this note, a novel robust control design for a class of pure unstable systems with time delay was addressed. In the algorithm, the time delay was not neglected as usual and was approximated as a stable component using improved Pade technique. The unstable system was mirror mapped into a stable system and subsequently the closed-loop gain shaping algorithm is used to design the robust control law. The proposed controller was easy to tune which had only one adjustable parameter with engineering sense. By virtue of the Nyquist stability criterion, the exact stabilization analysis has been obtained for the closed-loop system. Simulation results show that the control effects can tackle the input load disturbances and the delay perturbation more effectively. The method has the advantages of simple and efficient design.