Compensation of Time-Varying Delay in Networked Control System over Wi-Fi Network


  • Hyun-Chul Yi Pusan National University
  • Cheol-Jin An Pusan National University
  • Joon-Young Choi Pusan National University


networked control system (NCS), Wi-Fi network, time-varying delay, state predictor, rotary inverted pendulum


In this study, we design a state predictor-based output feedback controller that compensates for unavoidable time-varying network delays in networked control systems (NCSs) over Wi-Fi networks. We model time-varying network delays as timevarying input delays of NCSs over Wi-Fi networks. The designed controller consists of a linear quadratic regulator (LQR), a full-order observer, and a time-varying stepahead state predictor. The state predictor plays a key role in compensating for the time-varying input delay by providing the LQR with an estimation of future states ahead by the current network delay time. The time-varying network delays are acquired in real time by measuring the time differences between sent and received control data packets. We verify the stability and compensation performance of the designed controller by performing extensive experiments for an NCS in which a rotary inverted pendulum is controlled over Wi-Fi networks.

Author Biographies

Hyun-Chul Yi, Pusan National University

Department of Electronics Engineering

Cheol-Jin An, Pusan National University

Department of Electronics Engineering

Joon-Young Choi, Pusan National University

Department of Electronics Engineering


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