Rate-Adaptive Tasks: Model, Analysis, and Design Issues

In automotive systems, some of the engine control tasks are triggered by specific crankshaft rotation angles and are designed to adapt their functionality based on the angular velocity of the engine. This paper proposes a new task model for specifying such a type of real-time activities and presents an approach for analyzing the system feasibility under deadline scheduling for different scenarios. In particular, a feasibility test is derived for tasks under steady-state conditions (constant speed), as well as in dynamic conditions (constant acceleration). A design method is also discussed to determine the most suitable switching speeds for adapting the functionality of tasks without exceeding a desired utilization. Finally, a number of research directions are highlighted to extend the current results to more complex and realistic scenarios.