Stochastic analysis and control of real-time systems with random time delays

The paper discusses modeling and analysis of real-time systems subject to random time delays in the communication network. A new method for analysis of existing schemes is presented. The method is used to evaluate diierent suggested schemes from the literature. A new scheme for handling the random time delays is then developed and successfully compared with previous schemes. The new scheme is based on stochastic control theory and a separation property is shown to hold for the optimal controller. 1. INTRODUCTION Many real-time systems are implemented as distributed control systems, where the control loops are closed over a communication network. There will inevitably be time delays in the communication net. As long as the sampling periods are long compared with these delays there is no need to consider the innuence of the delays. As the demand on the control system increases it will be more and more important to take the delays into account in the analysis and the design of the control system. While inaccuracies, disturbances, etc, have been extensively studied in the control literature the timing problems in real-time systems have just recently attracted attention, and in the communication literature the feedback control aspect has not been treated extensively. This is thus an area where much can be gained by combining ideas from the two elds of control and real-time systems. Several problem formulations have been suggested by previous authors. A general setup would involve a dis