The control server: a computational model for real-time control tasks

The paper presents a computational model for real-time control tasks, with the primary goal of simplifying the control and scheduling codesign problem. The model combines time-triggered I/O and inter-task communication with dynamic, reservation-based task scheduling. To facilitate short input-output latencies, a task may be divided into several segments. Jitter is reduced by allowing communication only at the beginning and at the end of a segment. A key property of the model is that both schedulability and control performance of a control task will depend on the reserved utilization factor only. This enables controllers to be treated as scalable real-time components. The model has been implemented in a real-time kernel and validated in a real-time control application.