Memoryless input-output encoding for networked systems with unknown constant time delay

Communication time delay in a networked control system (NCS) degrades the performance and may lead to instability. The time delay value depends on the network configuration, e.g. number of nodes and is not exactly known during the controller design stage. Based on a novel delay-independent input-output approach the problem of unknown constant time delay is addressed in this paper. The plant and the controller input and output are encoded by a memoryless transformation into new variables which are transmitted over the communication channel. Thereby finite gain L₂stability is achieved. The performance of the memoryless encoding approach, validated in simulations and experiments, is superior over two other approaches, the standard small gain and a lead-lag control approach