SALSART - Predictably Flexible and Reliable Real-Time Systems



Start date:


Predictability and flexibility have often been considered as contradicting requirements, in particular from the scheduling perspective. This strong exclusion, however, holds only for predictability on a very detailed level, which is not demanded in most scenarios. Our research identifies appropriate levels of predictability, extends algorithms and architectures to combine static and dynamic components, and enables designers to combine predictability and flexibility.

Real-time systems need to be reliable in order to be applicable in real-world environment. Our approach to reliability follows the lines of timeliness: Instead of providing for static solutions only, we provide for adaptive fault tolerance and self-evolving systems. Issues include scheduling, dynamic reconfigurations of hardware structures, and reliability measures.

In addition to these core areas we are extending our results in cooperation with our partners to other areas such as robotics, control, and multi-agent systems for real-time industrial automation. We are developing the SALSART tool-suite for distributed schedule design and analysis to support our research.

The following are the concrete projects in this area:

Flexible Reliable Timing Constraints

Funding: ARTES and MdH
Project description:
The goal of this project is to develop methods for the derivation, specification, and run-time execution of activities with constraints, which exploit inherent flexibility in temporal demands, e.g., on application level, instead of over-constraining specifications. We propose to use flexible timing constraints, which express feasibility information of activities rather than numbers demanded by common system models and scheduling algorithms. These will be scheduled by novel offline algorithms, which are capable of exploiting the expressed flexibility, while maintaining reliability requirements.

Self-evolving Dependable Real-Time Systems

Funding: Volvo Research Foundation and MdH
Project description:

A majority of real-time systems facesdemands for changes during their lifetime: environment and controlledprocesses undergo different operational modes and reliability requirements,process improvements necessitate modification of parts of the real-time systemsitself, equipment is repaired or upgraded. Totally pre-designed systems, as iscurrently prevalent, cannot address such changes in an effective way.

This project proposes a “self-evolvingsystems” approach to handle such changes. The approach is based on twobasic principles: evolutionary nature and separation between servicesand server. Services broadcast admission requests to servers, and assignthemselves to servers with positive reply. Service requests include processing,networking, and reliability demands. A server is added by connecting to thenetwork, listening, and accepting services. Should a server node be removed orfail, its services reassign themselves. In an initialization phase, aguaranteed core of services can be configured, allowing for a tradeoffbetween determinism and flexibility. As servers and services interact forassignment via service demands and local server admission, the system can be heterogeneous.
The system evolves and parts of the system and processes can be replaced or modified.

[Show all publications]

RTOS support for mixed time-triggered and event-triggered task sets (Dec 2012)
Martijn van den Heuvel , Damir Isovic, Reinder Bril , Johan Lukkien , Gowri Sankar Ramachandran
10th IEEE/IFIP International Conference on Embedded and Ubiquitous Computing

Towards RTOS support for mixed time-triggered and event-triggered task sets (Sep 2012)
Martijn van den Heuvel , Reinder Bril , Damir Isovic, Johan Lukkien , Gowri Sankar Ramachandran
Emerging Technologies and Factory Automation (ETFA 2012)

Integrated Global and Local Quality-of-Service Adaptation in Distributed, Heterogeneous Systems (Dec 2007)
Larisa Rizvanovic, Damir Isovic, Gerhard Fohler
International IFIP Conference on Embedded and Ubiquitous Computing (EUC-07)

Real-Time Control and Scheduling Co-Design for Efficient Jitter Handling (Aug 2007)
Moris Behnam, Damir Isovic
The 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications

Real-time issues of MPEG-2 playout in resource constrained systems (Jun 2005)
Damir Isovic, Gerhard Fohler, Liesbeth Steffens
International Journal of Embedded Systems

Pre-Scheduling (May 2005)
Weirong Wang , Al Mok , Gerhard Fohler
Real-Time Systems Journal

Gerhard Fohler, Professor