Period Assignment for Real-Time Cascade Control Tasks Under Stability and Schedulability Constraints

Existing results for cyber-physical systems have been proposed to merge the requirements associated to the stability of the physical components and the schedulability of the cyber components. Nevertheless, none of the existing results has studied these requirements for multiple real-time cascade control tasks where their periods choice are dependent and affect stability. In this paper, we propose a methodology to evaluate the periods of the real-time cascade control tasks that ensures stability of the physical components, then we present a co-design problem for the period choice that guarantees good performance of the physical components and schedulability of the cyber components under fixed-priority scheduling. We then evaluate this methodology on a real use-case of a drone system. Results show the importance of studying these requirements together as their relation has an impact on stable periods range.