Performance limitations imposed by sensor time delays in a general 2-DOF control scheme

This paper extends previous work on performance limitations for discrete-time single-input single-output control systems containing sensor time delays. The areas of extension are the addition of more performance metrics (specifically, measures of disturbance rejection and sensor noise rejection), and the ability to derive performance limitations for unstable plants. The paper analyzes various control topologies and derives performance limitations for a general two degree-of-freedom control scheme; the performance bounds all worsen as the length of the sensor delay increases. The results in this paper are fundamental in that they apply to any linear time-invariant discrete-time controller