The Control Server Model for Co-Design of Real-Time Control Systems
Anton Cervin, Johan Eker · 2006
The paper presents the control server, a real-time scheduling mechanism tai-lored to control and signal processing applications. A control server creates the ab-straction of a control task with a specified period and a fixed input-output latency shorter than the period. Individual tasks can be combined into more complex com-ponents without loss of their individual guaranteed fixed-latency properties. I/O occurs at fixed predefined points in time, at which inputs are read or controller out-puts become visible. The control server model is especially suited for codesign of real-time control systems. The single parameter linking the scheduling design and the controller design is the task utilization factor. The proposed server is an exten-sion of the constant bandwidth server, which is based on the earliest-deadline-first scheduling algorithm. The server has been implemented in a real-time kernel and has also been validated in control experiments on a ball and beam process. 1