A new neuro-FDS definition for indirect adaptive control of unknown nonlinear systems using a method of parameter hopping

  • Authors:

  • Yiannis Boutalis;Dimitris C. Theodoridis;Manolis A. Christodoulou

  • Affiliations:

  • Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece and Department of Electrical, Electronic and Communication Engineering, University of Erlangen-Nu ...;Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece and Department of Industrial Informatics, Technological Educational Institute of Kavala, Greece;Department of Electronic and Computer Engineering, Technical University of Crete, Chania, Crete, Greece

  • Venue:
  • IEEE Transactions on Neural Networks
  • Year:
  • 2009

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Abstract

The indirect adaptive regulation of unknown nonlinear dynamical systems is considered in this paper. The method is based on a new neuro-fuzzy dynamical system (neuro-FDS) definition, which uses the concept of adaptive fuzzy systems (AFSs) operating in conjunction with high-order neural network functions (FHONNFs). Since the plant is considered unknown, we first propose its approximation by a special form of an FDS and then the fuzzy rules are approximated by appropriate HONNFs. Thus, the identification scheme leads up to a recurrent high-order neural network (RHONN), which however takes into account the fuzzy output partitions of the initial FDS. The proposed scheme does not require a priori experts' information on the number and type of input variable membership functions making it less vulnerable to initial design assumptions. Once the system is identified around an operation point, it is regulated to zero adaptively. Weight updating laws for the involved HONNFs are provided, which guarantee that both the identification error and the system states reach zero exponentially fast, while keeping all signals in the closed loop bounded. The existence of the control signal is always assured by introducing a novel method of parameter hopping, which is incorporated in the weight updating law. Simulations illustrate the potency of the method and comparisons with conventional approaches on benchmarking systems are given. Also, the applicability of the method is tested on a direct current (dc) motor system where it is shown that by following the proposed procedure one can obtain asymptotic regulation.