QRONOS

Quality-aware Co-Design of Responsive Real-Time Control Systems

(Own Funds)

Project leader: ,
Project members: , ,
Start date: 1. September 2015
End date: 30. September 2021
Acronym: QRONOS
URL: https://www4.cs.fau.de/Research/qronOS/

Abstract:

A key design goal of safety-critical control systems is the verifiable compliance with a specific quality objective in the sense of the quality of control. Corresponding to these requirements, the underlying real- time operating system has to provide resources and a certain quality of service. However, the relationship between real-time performance and quality of control is nontrivial: First of all, execution load varies considerably with environmental situation and disturbance. Vice versa, the actual execution conditions also have a qualitative influence on the control performance. Typically, substantial overestimations, in particular of the worst-case execution times, have to be made to ensure compliance with the aspired quality of control. This ultimately leads to a significant over-dimension of resources, with the degree disproportionately increasing with the complexity and dynamics of the control system under consideration. Consequently, it is to be expected that pessimistic design patterns and analysis techniques commonly used to date will no longer be viable in the future. Examples of this are complex, adaptive and mixed-critical assistance and autopilot functions in vehicles, where universal guarantees for all driving and environmental conditions are neither useful nor realistic. The issues outlined above can only be solved by an interdisciplinary approach to real-time control systems. This research project emanates from existing knowledge about the design of real-time control systems with soft, firm and hard timing guarantees. The basic assumption is that the control application's performance requirement varies significantly between typical and maximum disturbance and leads to situation-dependent reserves, correspondingly. Consequently, the commonly used pessimistic design and analysis of real-time systems that disregards quality-of- control dynamics is scrutinized. The research objective is the avoidance of pessimism in the design of hard real-time systems for control applications with strict guarantees and thus the resolution of the trade-off between quality-of-control guarantees and good average performance. This proposal pursues a co-design of control application and real-time executive and consists of the following three key aspects: model-based quality-of-control assessment, adaptive and predictive scheduling of control activities, and a hybrid execution model to regain guarantees.

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