Toward Automatic Synthesis of Schedulable Real-Time Controllers

This paper presents an automatic approach to synthesizing schedulable timing constraints for real-time control systems. Given the performance speciications and schedulability constraints of a real-time control system, the approach derives task-level timing constraints which can guarantee these requirements. The control performance is speciied in terms of control output responses such as steady state error, maximum overshoot, settling time, and rise time, and the task-level timing constraints include task periods and deadlines. The approach consists of two components with a clean interface. The rst component translates the performance speciications into a set of system-level timing constraints such as loop processing periods and input-to-output latency, via control theoretic modeling and optimization. The second then derives task-level timing constraints from the intermediate system-level timing constraints optimizing the system schedulability using period calibration method 4, 17, 9]. Our approach contributes to both the control and real-time areas: (1) it allows control engineers to take into consideration the eeect of task scheduling at the early stage of system design; and (2) it makes it possible to streamline the design of real-time control systems, since timing constraints are derived in an automatic manner.