Department of Control Engineering, Faculty of Electrical Engineering, K.N. Toosi University of Technology, P.O. Box 16315-1355, Tehran, Iran.
Industrial Control Center of Excellence, Faculty of Electrical Engineering, K.N. Toosi University of Technology, Tehran, Iran.
ISA Trans. 2015 May;56:28-41. doi: 10.1016/j.isatra.2014.11.014. Epub 2014 Dec 17.
In this paper, a novel adaptive hierarchical fuzzy control system based on the variable structure control is developed for a class of SISO canonical nonlinear systems in the presence of bounded disturbances. It is assumed that nonlinear functions of the systems be completely unknown. Switching surfaces are incorporated into the hierarchical fuzzy control scheme to ensure the system stability. A fuzzy soft switching system decides the operation area of the hierarchical fuzzy control and variable structure control systems. All the nonlinearly appeared parameters of conclusion parts of fuzzy blocks located in different layers of the hierarchical fuzzy control system are adjusted through adaptation laws deduced from the defined Lyapunov function. The proposed hierarchical fuzzy control system reduces the number of rules and consequently the number of tunable parameters with respect to the ordinary fuzzy control system. Global boundedness of the overall adaptive system and the desired precision are achieved using the proposed adaptive control system. In this study, an adaptive hierarchical fuzzy system is used for two objectives; it can be as a function approximator or a control system based on an intelligent-classic approach. Three theorems are proven to investigate the stability of the nonlinear dynamic systems. The important point about the proposed theorems is that they can be applied not only to hierarchical fuzzy controllers with different structures of hierarchical fuzzy controller, but also to ordinary fuzzy controllers. Therefore, the proposed algorithm is more general. To show the effectiveness of the proposed method four systems (two mechanical, one mathematical and one chaotic) are considered in simulations. Simulation results demonstrate the validity, efficiency and feasibility of the proposed approach to control of nonlinear dynamic systems.
本文针对一类存在有界干扰的 SISO 典型非线性系统，提出了一种基于变结构控制的新型自适应分层模糊控制系统。假设系统的非线性函数完全未知。在分层模糊控制方案中加入切换面以确保系统的稳定性。模糊软切换系统决定了分层模糊控制系统和变结构控制系统的工作区域。通过从定义的李雅普诺夫函数推导出的自适应律来调整位于分层模糊控制系统不同层的模糊块的结论部分中的非线性出现的参数。与普通模糊控制系统相比，所提出的分层模糊控制系统减少了规则的数量，从而减少了可调参数的数量。所提出的自适应控制系统可实现整个自适应系统的全局有界性和所需的精度。在本研究中，自适应分层模糊系统用于两个目的；它可以作为基于智能-经典方法的函数逼近器或控制系统。证明了三个定理来研究非线性动态系统的稳定性。所提出的定理的重要之处在于，它们不仅可以应用于具有不同分层模糊控制器结构的分层模糊控制器，也可以应用于普通模糊控制器。因此，所提出的算法更加通用。为了展示所提出方法的有效性，在仿真中考虑了四个系统（两个机械系统、一个数学系统和一个混沌系统）。仿真结果验证了所提出的非线性动态系统控制方法的有效性、效率和可行性。
