Reference Sliding Variable Based Chattering-Free Quasi-Sliding Mode Control

• Published in: IEEE access Vol. 8; pp. 133086 - 133094
• Main Author: Adamiak, Katarzyna
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Closed loop systems; Compensation; Continuous time systems; control design; control engineering; Control stability; Control theory; Controllers; Data systems; discrete time systems; disturbance compensation; Feedback control; Frequency control; reaching law approach; Robustness; sampled data circuits; Sampled data systems; Sliding mode control; Switches
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2020.3010900

The aim of this study is to design a new sliding mode controller with disturbance compensation for disturbed sampled data systems. As in such systems, the state measurements and control signal updates take place at the discrete time instants only, discrete time sliding mode analysis must be applied. Considering previous findings in this field, a new quasi-sliding mode controller, based on a reference sliding variable profile is developed. In order to eliminate the chattering problem, the reference is generated with a simple, nonswitching type reaching law. Next, the reference is incorporated into the control law for the real disturbed system. This approach limits the disturbance influence on the plant and results in an ultimate band width of <inline-formula> <tex-math notation="LaTeX">O(T) </tex-math></inline-formula> order. Furthermore, the proposed control strategy is extended with a disturbance compensation method, which allows to achieve the quasi-sliding mode band width of <inline-formula> <tex-math notation="LaTeX">O(T^{2}) </tex-math></inline-formula> order. Hence, the system's robustness improves with each reduction of the discretization period <inline-formula> <tex-math notation="LaTeX">T </tex-math></inline-formula>. The paper clearly shows that the proposed sliding mode controller guarantees stability of the closed-loop system and eliminates the chattering phenomenon.