Title: Improved reaching law-based sliding mode controller for free flight autopilot system

Authors: K.B. Devika; Susy Thomas

Addresses: Department of Electrical Engineering, National Institute of Technology, Calicut, India ' Department of Electrical Engineering, National Institute of Technology, Calicut, India

Abstract: This paper addresses the suitability of sliding mode control as a control strategy for free flight autopilot system. When used for practical applications, chattering which is an inherent limitation of SMC has to be mitigated adequately. Reaching law approaches for SMC design are being investigated in-order to identify an appropriate strategy that can ensure chattering-free operation for autopilot system. It is found that conventional reaching law-based SMC methodology leads to shortened sliding mode phase, slow system response and/or unbounded control action. Hence, each of the conventional reaching law methods are investigated not only for their efficacy in providing chattering free operation but also for sufficient sliding mode motion, fast response and bounded control action. Since it is observed that the conventional reaching laws fail in achieving these attributes concurrently, the authors propose an improved reaching law, viz., power rate exponential reaching law that can satisfy all the aforesaid desired attributes.

Keywords: air traffic control; ATC; chattering reduction; free flight; reaching law; sliding mode control; SMC.

DOI: 10.1504/IJAAC.2018.092847

International Journal of Automation and Control, 2018 Vol.12 No.3, pp.361 - 380

Received: 08 Nov 2016
Accepted: 03 Dec 2016
Published online: 01 Jul 2018 *

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