Fractional order [PI] Controller and Smith-like Predictor Design for A Class of High Order Systems
For control engineers dealing with high-order systems, this work offers an incremental improvement by extending Smith predictor and PI control to fractional order, with demonstrated benefits over integer-order methods.
This paper proposes a fractional order PI controller and Smith-like predictor for high-order systems of the form K/(Ts+1)^n, demonstrating zero steady-state error and disturbance rejection. Simulations using MO-GA show that choosing the fractional order ≤1 improves control performance and reduces control signal energy compared to integer-order predictors.
To handle the control difficulties caused by high-order dynamics, a control structure based on fractional order [proportional integral] (PI) controller and fractional order Smith-like predictor for a class of high order systems in the type of K/(Ts+1)n is proposed in this paper. The analysis of the tracking and disturbance rejection is illustrated based on the terminal value theorem and shows that the proposed control structure can ensure that the closed-loop system converges to the set point without static error and the closed-loop system recovers to its original state when the input disturbance occurs. Then, simulations about the influence on the control performance and control signal with different are carried out based on multi-objective genetic algorithm (MO-GA). The results show that the control performance can be improved and the energy of the control signal can be reduced simultaneously when the order is chosen no more than one. This can verify that the fractional order Smith-like predictor with has an advantage over that of the integral order Smith-like predictor.