Fatemeh Saeedizadeh - Mashhad Branch, Islamic Azad University, Iran
Naser Pariz - Ferdowsi University of Mashhad, Mashhad, Iran.
Seyyed Abed Hosseini - Research Center of Biomedical Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran.

A higher-order sliding approach to control a bioreactor model is proposed by non-commensurate fractional equations. The model outputs by the help of a controller reached the desired values and track them. According to existing conditions and chattering reduction, a high-order sliding mode has been chosen to design the controller. The purpose of the paper is to choose proper sliding surfaces. Here, for a better conclusion, a comparison has been made between the high-order sliding mode and the standard sliding mode. High-order sliding mode controllers have been taken in accordance with the structure of integer order system. Thus, in order for the system to apply more precise calculations, it should somehow turn to integer order. The sliding surfaces have been selected so appropriately that we can benefit from the structure of integer order controllers for fractional order system. The sliding surface in both controllers has also been the same so as to provide conditions for comparison. Finally, simulation results indicate that the high-order sliding mode controller has a great impact on chattering reduction.

bioreactor, Non-commensurate fractional equations, Chattering reduction, High- order sliding mode