Modeling and real time control of Internet-distributed control system

Internet-based control system (IBCS) is being widely researched for its novel function of allowing any user to teleoperate any Internet-connected device via Internet. But the realization on the system's topology is too superficial to discover its characters and advantages. Moreover, even some successful applications have shown it is possible to use the Internet for the real time remote control, research on the feasibility are so scarce that there is not a scale for the sense of the designs of real-time control over Internet. And the problem of real-time control caused by variable unpredictable time delay and package loss of Internet is still a primary hamper in the progress of IBCS, mainly because the model of the IBCS is not studied adequately. In this paper we firstly bring forward the concept of the Internet-distributed control system (IDCS) and its topology while two useful characters, self-organization and robustness, are introduced. The IDCS combining the Internet as a part of the control system is the general model of the IBCS. Then through a mathematical model of the IDCS, we show it is a nonlinear time-variable system with random character. Furthermore we prove that in an IDCS the requirement of real-time control with a sampling interval can not be satisfied completely and the feasibility of the requirement equals the real-time-ability of the control loop. According to this theory and considering the heterogeneous character of the IDCS, we propose a cooperative stream control scheme for multiple control streams called control streams manager (CSM), which is located at each component of IDCS and provides a cooperative stream control among multiple control streams.