Improved relay auto-tuning method for unstable TITO systems

In this paper, the relay auto-tuning method is improved by modifying the Zeigler-Nichols method to obtain the improved value of the controller gains of a TITO unstable system. The effect of the higher order harmonic terms are also taken into consideration while designing the controllers. The proposed method is simulated on two 2×2 unstable transfer function matrices. The implementation of the method does not need the knowledge of the transfer function matrix. The performance of the proposed method is compared with the conventional method of relay tuning. The present method gives improved response and reduced interactions. The present method is also robust.