Document Type : Original Research Paper

Authors

Shiraz University of Technology, Shiraz, Iran

Abstract

Background and Objectives: Nowadays, because of accuracy, speed, cost, and flexibility of digital control laws, control systems are implemented by computers, microprocessors or DSP chips. Therefore, many investigators have recently focused on the design of discrete-time controllers and computer-based control.
Methods: In this paper, a sliding mode controller based on the disturbance estimation is designed for a class of discrete-time nonlinear affine systems. Based on two disturbance compensator schemes, static and dynamic, procedures of sliding mode controller design are proposed for the discretetime system.
Results: In the case of measurable state variables, the instantaneous value of disturbances can be estimated based on the value of states and control signals. In two proposed control laws, there is no switching expression to induce the problem of chattering. Moreover, based on the necessary and sufficient quasi-sliding mode condition proposed by Sarpturk, boundedness and robustness of the proposed controllers is evaluated. In the case of constant or slowly time-varying disturbances, the quasi-sliding mode band converges asymptotically to zero and in this case, the proposed method is converted to the ideal sliding mode. Finally, two examples are provided to verify the proposed control laws and to compare the performance of the proposed controllers.
Conclusion: In this paper, a sliding mode controller based on the disturbance estimator was designed for a discrete-time nonlinear affine system. Due to the effectiveness of disturbance estimators in the performance of controllers, two kinds of disturbance estimators were considered. 


======================================================================================================
Copyrights
©2018 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.
======================================================================================================

Keywords

Main Subjects


LETTERS TO EDITOR

Journal of Electrical and Computer Engineering Innovations (JECEI) welcomes letters to the editor for the post-publication discussions and corrections which allows debate post publication on its site, through the Letters to Editor. Letters pertaining to manuscript published in JECEI should be sent to the editorial office of JECEI within three months of either online publication or before printed publication, except for critiques of original research. Following points are to be considering before sending the letters (comments) to the editor.


[1] Letters that include statements of statistics, facts, research, or theories should include appropriate references, although more than three are discouraged.

[2] Letters that are personal attacks on an author rather than thoughtful criticism of the author’s ideas will not be considered for publication.

[3] Letters can be no more than 300 words in length.

[4] Letter writers should include a statement at the beginning of the letter stating that it is being submitted either for publication or not.

[5] Anonymous letters will not be considered.

[6] Letter writers must include their city and state of residence or work.

[7] Letters will be edited for clarity and length.

CAPTCHA Image