Best Achievable Control Performance of Networked Systems Over Bandwidth-Constrained Channels

During data transmission, networked control systems (NCSs) are inevitably subject to constraints including bandwidth limitations, quantization effects, and time delays factors that exert a significant impact on the systems’ stability and control performance. This research explores the output tracking performance (OTP) of NCSs under the combined effects of uncertain time delays, bandwidth restrictions, and channel noise constraints. Through the adoption of first-order Pade approximation, all-pass factorization, and Youla parameterization techniques, the OTP bounds for single-degree-of-freedom systems and the modified performance limits for two-degree-of-freedom systems are derived analytically, yielding explicit formulations of the optimal performance. The results demonstrate that the OTP of NCSs is inherently associated with the intrinsic properties of the controlled plant and the parameters of the communication channel. Numerical simulations conducted on a metal rolling system further verify the theoretical predictions.