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 simplify ing the control and scheduling codesign problem. The model combines timetriggered I/O and intertask communication with dynamic, reservationbased task scheduling. To facilitate short inputoutput latencies, a task may be divided into several seg ments. 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 schedula bility 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 realtime kernel and validated in a realtime control application. 1