Two Degrees-of-Freedom Fractional-Order Proportional–Integral–Derivative-Based Temperature Control of Fermentation Process

Abstract

Temperature is one of the essential parameter in a fermentation process, which affects the thermal movement of cells. The temperature range for such processes is very tight and must be maintained precisely for efficient operation. Therefore, in this work combination of fractional calculus and two degrees-of-freedom proportional–integral–derivative (2DOF-PID) controller is proposed for desired temperature control of bioreactor. The 2DOF-PID controller incorporates an extra control loop, whereas fractional operator offers additional tractability for alteration in system dynamics. In order to achieve efficient execution of the control strategies, design parameters are optimized with the help of nondominated sorted genetic algorithm-II (NSGA-II) and Cuckoo search algorithm (CSA). NSGA-II-tuned controllers perform better than the CSA-tuned controllers. Further, the results show that the proposed controller regulates the temperature of bioreactor in a more robust and efficient manner in comparison to other designed controllers.