An estimator to characterize varying time delays based on cross‐correlation function for the tuning of IP network‐based small DC motor speed control

Internet protocol (IP) network‐based control systems have recently attracted interest. There is, however, the problem such that varying time delays and packet losses in the networks induce performance degradation. Therefore, it is important how the traffic conditions are characterized. Conventional methods have characterized varying time delays based on round trip times (RTTs). In this paper, we propose an estimator to characterize the delays based on the cross‐correlation function. The tuning of the proportional‐integral (PI) controller is done using the estimator, and speed control experiments of the system for a small DC motor are done. As a result, it has been confirmed that the estimator is usable for tuning. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.