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Unknown input observer‐based robust adaptive funnel motion control for nonlinear servomechanisms
Author(s) -
Wang Shubo,
Na Jing,
Ren Xuemei,
Yu Haisheng,
Yu Jinpeng
Publication year - 2018
Publication title -
international journal of robust and nonlinear control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.361
H-Index - 106
eISSN - 1099-1239
pISSN - 1049-8923
DOI - 10.1002/rnc.4368
Subject(s) - control theory (sociology) , funnel , nonlinear system , sliding mode control , controller (irrigation) , variable structure control , observer (physics) , tracking error , adaptive control , computer science , mathematics , engineering , control (management) , artificial intelligence , physics , mechanical engineering , agronomy , quantum mechanics , biology
Summary In this paper, an unknown input observer is proposed for servomechanisms with unknown dynamics (eg, nonlinear friction, parameter uncertainties, and external disturbance). An unknown input observer is developed by introducing auxiliary filtered variables in terms of first‐order low‐pass filters, where only one constant (filter parameter) needs to be tuned. A modified funnel variable is developed by using the tracking error to replace the scaling factor to improve the transient and steady‐state performance of the control systems. Then, a sliding mode surface with the new transformed error is defined and used to design a funnel nonsingular terminal sliding mode controller to achieve finite‐time convergence. In addition, the proposed funnel nonsingular terminal sliding mode controller method avoids the singularity problem in the conventional sliding mode control via modifying the terminal sliding manifold. Finally, experimental results are given to illustrate the effectiveness of the suggested control scheme.