Stability and Worst-Case Performance Analysis of Sampled-Data Control Systems with Input and Output Jitter

When a feedback controller is implemented in a networked embedded system, the computations and communications induce delays and jitter, which may destabilize the control loop. The majority of previous work on analysis of control loops with time-varying delays has focused on output (actuation) jitter. In many embedded systems, input (sampling) jitter is also an issue. In this paper, we analyze the combined effect of input and output jitter on the stability and performance of linear sampled-data control systems. The analysis is performed via a loop transformation involving two time-varying uncertainties. We show how the input-output gains of the linear part of the transformed system can be computed using a fast-sampling/fast-hold approximation. At the same time, we reduce the conservativeness of a previous stability theorem for pure output jitter.