Brief paper: Output feedback adaptive control of a class of nonlinear discrete-time systems with unknown control directions

  • Authors:
  • Chenguang Yang;Shuzhi Sam Ge;Tong Heng Lee

  • Affiliations:
  • Social Robotics Lab, Interactive Digital Media Institute, and Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore;Social Robotics Lab, Interactive Digital Media Institute, and Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore;Social Robotics Lab, Interactive Digital Media Institute, and Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore

  • Venue:
  • Automatica (Journal of IFAC)
  • Year:
  • 2009

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Abstract

In this paper, output feedback adaptive control is investigated for a class of nonlinear systems in output-feedback form with unknown control gains. To construct output feedback control, the system is transformed into the form of the NARMA (nonlinear-auto-regressive-moving-average) model, based on which future output prediction is carried out. With employment of the predicted future output, a constructive output feedback adaptive control is given with the discrete Nussbaum gain exploited to overcome the difficulty due to unknown control directions. Under the global Lipschitz condition of the system functions, the boundedness of all the closed-loop signals and asymptotical output tracking are achieved by the proposed control. Simulation results are presented to show the effectiveness of the proposed approach.