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Modified multirate output feedback based discrete sliding mode control for input chattering reduction

Ngadengon@Ngadungon , Rafidah (2017) Modified multirate output feedback based discrete sliding mode control for input chattering reduction. PhD thesis, Universiti Teknologi Malaysia.

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Abstract

An inverted pendulum system is known as a highly nonlinear and unstable system. In this thesis, a model of an inverted pendulum system involving uncertainties due to the presence of measurement error and external disturbance was formulated. A Sliding Mode Control (SMC) is an effective approach to control nonlinear uncertain systems caused by its inherent insensitivity property to parameter variations and external disturbances. A variant of the Discrete Sliding Mode Control (DSMC) known as Multirate Output Feedback (MROF) was chosen to design the proposed controller because the algorithm for MROF only makes use the output samples for designing the controller. Similar to conventional SMC, MROF also possesses undesirable chattering problem. Chattering leads to low control accuracy and high wear of moving mechanical components. Therefore, a new reaching law was developed to reduce the effect of chattering. By employing the new reaching law and knowing the bound values of the disturbance system parameters, a new MROF based DSMC was designed. Extensive simulations were performed and the results show that the proposed controller has performed well in reducing the chattering at the control input. The proposed reaching law generated better control performance with the percentage of the Quasi Sliding Mode Band (QSMB) was reduced to 44%. While the chattering in control input was reduced to 53%. Meanwhile the second controller used MROF with Discrete Integral Sliding Mode Control (DISMC). The upper and lower bounds of the disturbance is assumed to be unknown during the design of the controller. The findings demonstrated that the MROF based DISMC provided better system response as compared to the Discrete Linear Quadratic Regulator (DLQR) and discrete Proportional Integral Derivative (PID). The result for MROF based DSMC and DISMC showed that the width of the chattering was able to be reduced and it can achieve reachability condition even with the presence of uncertainties in the inverted pendulum system.

Item Type: Thesis (PhD)
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ212-225 Control engineering systems. Automatic machinery (General)
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 13 Aug 2018 03:27
Last Modified: 13 Aug 2018 03:27
URI: http://eprints.uthm.edu.my/id/eprint/10270
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