Intelligent Adaptive Learning and Control for Discrete-Time Nonlinear Uncertain Systems In Multiple Environments

2021 ◽  
Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Cong Wang ◽  
Wei Zeng ◽  
Shi-Lu Dai
Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Paolo Stegagno

Abstract In this paper, we propose a novel intelligent control scheme for a class of discrete-time nonlinear uncertain systems operating under multiple environments/control situations. First, based on the deterministic learning theory, artificial neural networks (NNs) are employed to accurately learn/identify the uncertain system dynamics under each individual environment. The learned knowledge is then utilized to: (i) achieve improved control performance by developing a family of experience-based controllers (EBCs), each of which is tailored to an individual environment; and (ii) determine real-time activation of the EBCs by developing a pattern recognition mechanism for online identifying the active control situation. In addition, a robust quasi-sliding mode controller is further designed and embedded in the overall control scheme to guarantee system stability during the transition process among multiple environments. The novelty of the proposed control scheme lies in its intelligent capabilities of knowledge acquisition and re-utilization in real-time control, enabling self-adaption to uncertain changing control environments. A simulation example is included to verify the effectiveness of the proposed results.


Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Paolo Stegagno

Abstract This paper addresses the problem of composite tracking control and adaptive learning for discrete-time nonlinear uncertain systems in a general normal form. This problem specifies a joint objective of stable tracking control and accurate learning/identifying the associated ideal control strategy simultaneously, in which the “ideal control strategy” is defined to be the tracking controller structure that is typically adopted when the controlled plant’s nonlinear dynamics are precisely known. To this end, a novel adaptive neural network (NN) learning controller is proposed based on the deterministic learning theory. Compared with existing adaptive NN control approaches, the proposed controller is capable of rendering not only stable tracking control, but also accurate learning/identifying the ideal tracking control strategy. Moreover, the learned knowledge can be effectively represented and stored as constant NN models, whose weights are guaranteed to converge to ideal/optimal values. Based on this, an experience-based controller is also constructed to achieve desired tracking control performance without online adaptation, leading to reduced computational cost and improved controlled performance. Numerical simulations have been conducted to demonstrate the effectiveness of the proposed approach.


2020 ◽  
Vol 390 ◽  
pp. 168-184
Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Cong Wang ◽  
Paolo Stegagno ◽  
Wei Zeng

2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Paolo Stegagno ◽  
Haibo He ◽  
Cong Wang

Author(s):  
Jingting Zhang ◽  
Chengzhi Yuan ◽  
Paolo Stegagno

Abstract This paper addresses the problem of small fault detection for discrete-time nonlinear uncertain systems. The problem is challenging due to (i) the considered system is subject to unstructured nonlinear uncertain dynamics; and (ii) the faults are considered to be “small” in the sense that system states and control inputs in faulty mode remain close to those in normal mode. To overcome these challenges, a novel adaptive dynamics learning based fault detection scheme is proposed. Specifically, an adaptive dynamics learning approach is first proposed to achieve the locally-accurate approximation of the system uncertain dynamics. Then, based on the learned knowledge, a novel residual system is designed by using the absolute measures of the change of the system dynamics resulting from the fault effect. An adaptive threshold is developed based on the residual system for real-time decision making, i.e., the fault is claimed to be detected when the associated residual signal becomes larger than the adaptive threshold. Rigorous analysis is performed to deduce the small fault detectability condition, which is shown to be significantly relaxed compared to those of existing fault detection methods. Extensive simulations have also been conducted to demonstrate the effectiveness and advantages of the proposed approach.


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