| 1. |
- Andersson, Martin, et al.
(författare)
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Co-simulation of Mobile Wireless Networked Embedded Systems in Physical Environments
- 2005
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Ingår i: RTiS 2005 – Proceedings of Real Time in Sweden 2005, the 8th Biennial SNART Conference on Real-Time Systems (Skövde University Studies in Informatics). - 1653-2325. - 9163173492 ; 2005:1
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Konferensbidrag (refereegranskat)abstract
- Embedded systems are becoming increasingly networked and aredeployed in application areas that require close interaction withtheir physical environment. Examples include distributed mobileagents and wireless sensor/actuator networks. The complexity ofthese applications make co-simulation a necessary tool during systemdevelopment. This paper presents a simulation environment thatfacilitates simulation of computer nodes and communication networksinteracting with the continuous-time dynamics of the real world.Features of the simulator include interrupthandling, task scheduling, wired and wireless communication, localclocks, dynamic voltage scaling, and battery-driven operation.Two simulation case studies are presented: a simple communicationscenario and a mobile robot soccer game.
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| 2. |
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| 3. |
- Mohaqeqi, Morteza, et al.
(författare)
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On the problem of finding optimal harmonic periods
- 2016
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Ingår i: Proc. 24th International Conference on Real-Time Networks and Systems. - New York : ACM Press. - 9781450347877 ; , s. 171-180
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Konferensbidrag (refereegranskat)
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| 4. |
- Mohaqeqi, Morteza, et al.
(författare)
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Optimal harmonic period assignment: complexity results and approximation algorithms
- 2018
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Ingår i: Real-time systems. - : Springer. - 0922-6443 .- 1573-1383. ; 54:4, s. 830-860
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Tidskriftsartikel (refereegranskat)abstract
- Harmonic periods have wide applicability in industrial real-time systems. Rate monotonic (RM) is able to schedule task sets with harmonic periods up to 100% utilization. Also, if there is no release jitter and execution time variation, RM and EDF generate the same schedule for each instance of a task. As a result, all instances of a task are interfered by the same amount of workload. This property decreases the jitters that happen during sampling and actuation of the tasks, and hence, it increases the quality of service in control systems. In this paper, we consider the problem of optimal period assignment where the periods are constrained to be harmonic and the task set is required to be feasible. We study two variants of this problem. In the first one, the objective is to maximize the system utilization, while in the second one, the goal is to minimize the total weighted sum of the periods. First, we assume that an interval is determined a priori for each task from which its period can be selected. We show that both variants of the problem are (at least) weakly NP-hard. This is shown by reducing the NP-complete number partitioning problem to the mentioned harmonic period assignment problems. Afterwards, we consider a variant of the second problem in which the periods are not restricted to a special interval. We present two approximation algorithms with polynomial-time complexity for this problem and show that the maximum relative error of these algorithms is bounded by a factor of 1.125. Our evaluations show that, on the average, results of the approximation algorithms are very close to an optimal solution.
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| 8. |
- Aminifar, Amir, et al.
(författare)
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Control-Quality Driven Design of Cyber-Physical Systems with Robustness Guarantees
- 2013
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Ingår i: Design, Automation & Test in Europe (DATE 2013). - : IEEE. - 1530-1591. - 9781467350716 ; , s. 1093-1098
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Konferensbidrag (refereegranskat)abstract
- Many cyber-physical systems comprise several control applications sharing communication and computation resources. The design of such systems requires special attention due to the complex timing behavior that can lead to poor control quality or even instability. The two main requirements of control applications are: (1) robustness and, in particular, stability and (2) high control quality. Although it is essential to guarantee stability and provide a certain degree of robustness even in the worst-case scenario, a design procedure which merely takes the worst-case scenario into consideration can lead to a poor expected (average-case) control quality, since the design is solely tuned to a scenario that occurs very rarely. On the other hand, considering only the expected quality of control does not necessarily provide robustness and stability in the worst-case. Therefore, both the robustness and the expected control quality should be taken into account in the design process. This paper presents an efficient and integrated approach for designing high-quality cyber-physical systems with robustness guarantees.
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| 9. |
- Aminifar, Amir, et al.
(författare)
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Control-Quality Driven Design of Embedded Control Systems with Stability Guarantees
- 2018
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Ingår i: IEEE Design and Test. - : IEEE. - 2168-2356 .- 2168-2364. ; 35:4, s. 38-46
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Tidskriftsartikel (refereegranskat)abstract
- Today, the majority of control applications in embedded systems, e.g., in the automotive domain, are implemented as software tasks on shared platforms. Ignoring implementation impacts during the design of embedded control systems results in complex timing behaviors that may lead to poor performance and, in the worst case, instability of control applications. This article presents a methodology for implementation-aware design of high-quality and stable embedded control systems on shared platforms with complex timing behaviors.
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| 10. |
- Aminifar, Amir, et al.
(författare)
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Designing High-Quality Embedded Control Systems with Guaranteed Stability
- 2012
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Ingår i: 33rd IEEE Real-Time Systems Symposium (RTSS 2012. - 1052-8725. - 9781467330985
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Konferensbidrag (refereegranskat)abstract
- Many embedded systems comprise several controllers sharing available resources. It is well known that such resource sharing leads to complex timing behavior that degrades the quality of control, and more importantly, can jeopardize stability in the worst-case, if not properly taken into account during design. Although stability of the control applications is absolutely essential, a design flow driven by the worst-case scenario often leads to poor control quality due to the significant amount of pessimism involved and the fact that the worst-case scenario occurs very rarely. On the other hand, designing the system merely based on control quality, determined by the expected (average-case) behavior, does not guarantee the stability of control applications in the worst-case. Therefore, both control quality and worst-case stability have to be considered during the design process, i.e., period assignment, task scheduling, and control-synthesis. In this paper, we present an integrated approach for designing high-quality embedded control systems, while guaranteeing their stability.
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