An experimental HIL study on the jitter sensitivity of an adaptive control system

It has been widely accepted that real-time implementations of feedback control systems can be susceptible to timing jitters which may be caused by the underlying real-time and/or embedded implementation architecture. Previous experimental studies aimed at quantifying the levels of degradation that may be observed have mainly concentrated upon relatively simple fixed-gain feedback control schemes (e.g. PID) and time-invariant plant. Although some degradation has been observed, most systems have been shown to be surprisingly robust unless driven to extreme limits. In this paper, we study the jitter sensitivity of a real-time embedded implementation of a digital parameter-adaptive control system. The purpose of the study was two-fold; primarily, to obtain empirical data related to jitter sensitivity (as measured by a quadratic performance metric), and secondarily to explore the potential impact of the underlying scheduler choice on system behavior. The findings indicate that the adaptive controller was heavily influenced by sampling jitter, and that the choice of task scheduler had a role to play.