Schedulability issues in complex embedded control systems

The design of embedded control systems should be addressed in both the controller definition and its implementation. While the design of the controller is based on control theory, the implementation is designed by assuming the principle that control loops can be modeled and implemented as periodic activities. Periodic activities that can be organise attending to different implementation criteria. Recently, the authors have introduced the concept of control kernel dealing with the essential control activities to guarantee the safe behaviour of the complete system. For this purpose, we propose a control arrangement in different layers. At the level of the OS, activities to closing the loop and driving the system to a safe position should be included. At the top level, the control system may include several on-line controller options as well as supervising and optimising activities. This part should be independent of both the particular implementation and the resources availability. In this paper we propose an implementation and a scheduling scheme to implement complex control applications.