Identification and control of Hammerstein systems via wireless networks

Abstract

This article investigates a systematic approach for the identification and control of Hammerstein systems over a physical IEEE 802.11b wireless channel. Three major factors which may affect system stability and stabilisation are concerned: wireless network-induced delays, nonlinearity and model mismatch. First the network-induced delays are characterised by an inverse Gaussian distribution model according to IEEE 802.11b protocol and a model-based compensation method is used to estimate the delayed samples. Then an inverse function of nonlinear part of the identified model is used to attenuate the influence of nonlinearity, while the model mismatch is regarded as disturbance which is then dealt with by H _∞ control approach. A sufficient condition for mean-square asymptotic stability is obtained and expressed by a set of linear matrix inequalities, enabling direct controller design. Finally, numerical simulation examples are used to confirm the efficacy of the proposed approach.

Keywords:

• wireless networked control
• system identification
• Hammerstein system
• linear matrix inequalities

Acknowledgements

This work was financially supported by the National Science Foundation of China under Grants 60834002, 61074032, 60904016, 61104089, the Research Councils UK under Grant No. EP/G042594/1, The Excellent Discipline Head Plan Project of Shanghai under Grant 08XD14018, the Project of Science and Technology Commission of Shanghai Municipality under Grant 11ZR1413100 and 10JC1405000, the Graduate Student Innovation Fund of Shanghai University under Grant SHUCX101016, Shanghai Key Laboratory of Power Station Automation Technology and The Mechatronics Engineering Innovation Group project from Shanghai Education Commission, Leading Academic Discipline Project MEE&AMA of Shanghai University.