Robust Performance Issues in Tracking Control over Networks

This paper is concerned with the investigation of robust performance of linear tracking controllers affected by un-modelled delays acting in the loop. The incentive comes from the area of Networked Control System (NCS) where the inevitable network-induced (transmission) delays are either time-varying or constant. The main contribution (based on extensive simulation work rather than strict mathematical proof) is that the tracking performance of (typical or more sophisticated) linear tracking control laws is drastically reduced when applied to NCS. The provided simulation results (i) demonstrate the impact of the network-induced delays on the tracking performance of single-input single-output NCS, (ii) provide initial guidelines for the tuning of the controllers and (iii) pave the road for further work to be done.