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Title: Design of sliding mode-based nonlinear control systems with nonlinear full-order state observers for underactuated coupled systems
Author: Firdaus, Ahmad Riyad
ISNI:       0000 0004 7233 8553
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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This thesis presents the development of new nonlinear control algorithms with full-order state observers to overcome the control challenges encountered with nonlinear and underactuated systems. Quadcopter unmanned aerial vehicles are good example of underactuated systems, and this is selected in this research for validating the developed control and observer systems. It is shown through review of the literature that sliding mode control and sliding mode observer have many advantages over other control and observer methods in dealing with nonlinearity, underactuation, and coupled systems. However, the chattering phenomenon noted in such approaches can degrade the overall performance of the system. In this work, new methods to tackle the issue are proposed by employing sliding mode-based interval type-2 fuzzy control and sliding mode-based interval type-2 fuzzy observer. Moreover, in terms of control system, set-point weighting function and integral term are proposed and incorporated into the control system to improve the overall performance of the system. Furthermore, the weighting and integral terms are utilized to design further sliding mode-based control systems, including: quasi-sliding mode control, super-twisting algorithm of sliding mode control, and dynamic sliding mode control. In terms of observer, for the purposes of performance comparison, other nonlinear observer approaches are designed including: quasi-sliding mode observer, super-twisting algorithm of sliding mode observer, high order sliding mode observer, and extended Kalman filter. All designed control and observer methods are evaluated and compared their performances based on predefined performance criteria through numerical simulations. Wellperforming control and observer methods in simulated exercises are selected for further analysis and validation with real-time experimental investigations. From the simulation results obtained, overall set-point integral quasi-sliding mode control and quasi-sliding mode observer have performed better than other methods. The proposed methods of employing set-point weighting function and integral term to sliding mode-based control systems have performed very well in reducing overshoot, rise time, and steady-state errors. Meanwhile, in terms of experimental validations, set-point integral super-twisting algorithm of sliding mode control has shown better ability than set-point integral quasi-sliding mode control, and the observer method of quasi-sliding mode observer has yielded 2nd - order state well.
Supervisor: Tokhi, M. Osman Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available