Multi-loop control structures can enhance inherent disturbance rejection capacity of classical closed loop control loops: While the classical closed loop PID control loop (inner loop) deals with stability and set-point control, the additional model reference control loop of MIT rule (outer loop) can improve the disturbance rejection control performance without degrading the optimal set-point control performance. Such adaptive disturbance rejection, which is not influencing the set-point control performance, can be achieved by selecting reference models as transfer functions of PID control loops (with ignorable time delay)
 Alagoz, B. B., Tepljakov, A., Petlenkov, E., & Yeroglu, C. (2020). Multi-Loop Model Reference Proportional Integral Derivative Controls: Design and Performance Evaluations. Algorithms, 13(2), 38.  Alagoz, B.B., Kavuran, G., Ates, A., Yeroglu, C., Alisoy, H. (2019). Multi-loop model reference adaptive PID control for fault-tolerance. Balkan Journal of Electrical and Computer Engineering, 7(3), 276-285.  Tepljakov, A., Alagoz, B. B., Gonzalez, E., Petlenkov, E., & Yeroglu, C. (2018). Model reference adaptive control scheme for retuning method-based fractional-order PID control with disturbance rejection applied to closed-loop control of a magnetic levitation system. Journal of Circuits, Systems and Computers, 27(11), 1850176.  Alimohammadi, H., Alagoz, B. B., Tepljakov, A., Vassiljeva, K., & Petlenkov, E. (2020). A NARX Model Reference Adaptive Control Scheme: Improved Disturbance Rejection Fractional-Order PID Control of an Experimental Magnetic Levitation System. Algorithms, 13(8), 201.
Find the treasures in MATLAB Central and discover how the community can help you!Start Hunting!