Improved Robustness and Finite Time Convergence for a Multivariable Process using Integral Terminal Sliding Mode Controller via Multilevel Switching

Abstract

<span style="font-size:9.0pt;background:white;mso-bidi-font-style:italic" lang="EN-GB">This paper discusses the control of non-linear multivariable process named as Completely Modified Quadruple Tank Process (CMQTP) operating in Minimum Phase (MP). Initially PI (Proportional Integral) controller is designed to control the level of bottom two tanks. Then Sliding Mode Controller (SMC) strategy is designed with relative degree two. In order to reduce the control input effort, Back stepping Sliding Mode Controller (BSMC) is introduced. For a finite settling time and robust performance, Terminal Sliding Mode Controller (TSMC) is used. To improve the controller performance, integrality property is added to TSMC which leads to Integral Terminal Sliding Mode Controller (ITSMC). The undesirable chattering effect is reduced by introducing a novel Multi level switching algorithm. The complexities in CMQTP is discussed and compared with Quadruple Tank Process (QTP) through mathematical analysis. All the above mentioned controllers are compared using MATLAB simulation. From the simulated responses, the performance of proposed ITSMC is elucidated with good robustness, better servo tracking and disturbance rejection along with improved performance indices.

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