PID tuning by a composed structure

This paper proposes a way to reduce the excessive overshoot produced by the tuning of Ziegler-Nichols method using a structure, called the composed structure, and by weighting the three actions of the PID controller by three factors (F_p, F_i, F_d ). These factors are determined as a function of system parameters so as to guarantee a specified overshoot in closed-loop. The usual parameters (K, T_i, T_d) of the PID are fixed by the tuning of Ziegler-Nichols method which provides a good rejection of the load disturbance