Stable iterative feedback tuning method for servo systems

This paper presents an Iterative Feedback Tuning (IFT) method to guarantee the control system stability throughout the iterations. The theoretical framework is based on the closed-loop stability testing in the context of coprime factor uncertainty for the controller, and it makes use of the small gain theorem for discrete-time systems. Bounds on the gain of the systems involved in the stability analysis are found from nonparametric models in frequency domain. A digitally simulated case study concerning the angular position control of a servo system is included to validate the new stable IFT method.