1Faculty of Engineering and Surveying

Abstract: The performance of a networked control system (NCS) is affected directly and indirectly by time delays generated in network communication. This paper addresses these time delays, their effects on system performance, and the measures taken in an NCS design. For a time delay which is random but less than one sampling interval T, we model the system as a time-invariant control system with constant time delay T. For a time delay which is random and greater than one sampling interval T, we consider the system as a control system with packet drop and model it as a jump linear control system. Based on the above models, we propose a systematic method to improve the control system quality of performance by choosing a proper sampling interval to reduce data transmission, optimally scheduling to minimize packet loss and optimizing controller design in case of packet loss. The simulation results in lab experiments demonstrate that the design method results in high performance in networked real-time control system. Key words: Real-time system, networked control system, time delay, packet drop, optimal control