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Tracking control for lower limb rehabilitation robots based on polynomial nonlinear uncertain models
Author(s) -
Li Ying,
Ke Jin,
Zeng Jianping
Publication year - 2021
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.5381
Subject(s) - control theory (sociology) , nonlinear system , robot , trajectory , polynomial , tracking (education) , computer science , explained sum of squares , observer (physics) , controller (irrigation) , control engineering , control (management) , mathematics , engineering , artificial intelligence , psychology , mathematical analysis , pedagogy , physics , quantum mechanics , astronomy , machine learning , agronomy , biology
This paper aims to propose a novel idea for the modeling and trajectory tracking control of a lower limb rehabilitation robot. A polynomial nonlinear uncertain model is established to deal with the difficulty of accurate modeling for the lower limb rehabilitation robot with complex dynamic characteristics. A high‐order nonlinear disturbance observer (HONDO) is utilized to estimate the lumped disturbance with fast time‐varying and the corresponding observer gain matrix is obtained by H ∞ performance. Then an HONDO‐based composite tracking controller is designed to achieve good tracking performance of the lower limb rehabilitation robot. In addition, all solvability conditions can be directly handled by sum of squares programming, effectively avoiding the calculation problem. Finally, numerical simulations are conducted to verify the validity of the proposed method.