Play-back buffers in networked control systems: Evaluation and design

The networked environment presents many new challenges for the design of feedback control systems. A specific problem is that networked control systems (NCSs) are subject to the performance-degrading effects of time-varying, random loop delays. Model predictive controllers are a well-known method for delay compensation, but often exhibit poor performance under these types of loop delay. This paper investigates the use of play-back buffers to remove the uncertainty in the delay. First we study the value of removing all delay uncertainty with comparisons to unbuffered PID control using a bounded- interval delay distribution, and then we explore optimal playback buffer design for bounded-interval and heavy-tailed delay distributions.