A new method for controlling the plant in networked control systems (NCSs) is proposed. Network time delay and packet loss are two major drawbacks in data communication networks which make NCSs unstable. Unlike previous related research works, this new proposed rotating PI controller based method has the advantage of considering time delay and packet loss effects simultaneously. Time delay is estimated online and then used for tuning the PI controller by rotating the phase plane, while packet loss sequences are modeled by Markov chain. This novel method improves the performance compared to other methods, especially when packets are dropped consecutively and network time delays are large. In fact, the results show that with the network time delay as large as 600 ms, and packet loss occurring evenly, the index of the rotating PI controller performance will be improved by approximately two and a half times compared to the performance index of classical Smith predictor. This ratio will be improved by approximately eight and a half times compared to the performance index of PI controller. Furthermore, in the case that the packet loss occurs consecutively, the results show a ratio improvement of approximately three and ten for our suggested method in comparison to Smith predictor and PI controller, respectively.
Digital Object Identifier (DOI)
Hajebi, Pooya and Mohammad Taghi AlModarresi, Seyed
"Online Rotating PI Controller for NCS Over Communication Constraints,"
Applied Mathematics & Information Sciences: Vol. 10
, Article 24.
Available at: https://dc.naturalspublishing.com/amis/vol10/iss5/24