Real time implementation of Modified Repetitive Control Strategy in a DC motor

In this paper the Modified Repetitive Control Strategy (MRCS) is designed and implemented in a DC motor. The MRCS incorporates the idea of repetitive control strategy (RCS) which accomplishes perfect asymptotic set point tracking in this process, provided that the period length used in the control formulation matches the actual period of the reference/disturbance signal exactly. The DC motor system is approximated into a First Order Plus Time Delay (FOPTD) model by step testing method. RCS is incorporated in the DC motor control loop of proportional (P) mode. The proportional controller parameter is obtained using Ziegler-Nichols Tuning Rule (ZNTR). The proposed MRCS is also integrated to a DC motor system. A periodic input signal of sine wave is generated and real time runs of the DC motor system are carried out for the periodic reference tracking with MRCS based P mode control loop. A similar run is also carried out with both RCS based P mode and conventional P-mode control structure in the loop. The experimental results show that the MRCS demonstrated good tracking performance. A robustness of the MRCS is also validated.