Cyber-Physical Systems (CPS) are widely deployed in critical applications which are subject to strict timing constraints. To ensure correct timing behavior, much of the effort has been dedicated to the development of validation and verification methods for CPS (e.g., system models and their timing and schedulability analysis). As CPS is becoming increasingly complex, there is an urgent need for efficient optimization techniques that can aid the design of large-scale systems. Specifically, techniques that can find good design options in a reasonable amount of time while meeting all the timing and other critical requirements are becoming vital. However, the current mindset is to use existing schedulability analysis and optimization techniques for the design optimization of time-critical CPS. This has resulted in two issues in today's CPS design: 1) Existing timing and schedulability analysis are very difficult and inefficient to be integrated into well-established optimization frameworks such as mathematical programming; 2) New system models and timing analysis are being developed in a way that is increasingly unfriendly to optimization. Due to these difficulties, existing practice for optimization mostly relies on meta or ad-hoc heuristics, which suffers either from sub-optimality or limited applicability. In this dissertation, we seek to address these issues and explore two new directions for developing optimization algorithms for time-critical CPS. The first is to develop {em optimization-oriented timing analysis}, that are efficient to formulate in mathematical programming framework. The second is a domain-specific optimization framework. The framework leverages domain-specific knowledge to provide methods that abstract timing analysis into a simple mathematical form. This allows to efficiently handle the complexity of timing analysis in optimization algorithms. The results on a number of case studies show that the proposed approaches have the potential to significantly improve upon scalability (several orders of magnitude faster) and solution quality, while being applicable to various system models, timing analysis techniques, and design optimization problems in time-critical CPS. / Doctor of Philosophy / Cyber-Physical Systems (CPS) tightly intertwine computing units and physical plants to accomplish complex tasks such as control and monitoring. They are often deployed in critical applications subject to strict timing constraints. For example, many control applications and tasks are required to finished within bounded latencies. To guarantee such timing correctness, much of the effort has been dedicated to studying methods for delay and latency estimation. These techniques are known as schedulability analysis/timing analysis. As CPS becomes increasingly complex, there is an urgent need for efficient optimization techniques that can aid the design of large-scale and correct CPS. Specifically, techniques that can find good design options in reasonable amount of time while meeting all the timing and other critical requirements are becoming vital. However, most of the existing schedulability analysis are either non-linear, non-convex, non-continuous or without closed form. This gives significant challenge for integrating these analysis into optimization. In this dissertation, we explore two new paradigm-shifting approaches for developing optimization algorithms for the design of CPS. Experimental evaluations on both synthetic and industrial case studies show that the new approaches significantly improve upon existing optimization techniques in terms of scalability and quality of solution.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/96520 |
| Date | 20 January 2020 |
| Creators | Zhao, Yecheng |
| Contributors | Electrical and Computer Engineering, Zeng, Haibo, Hsiao, Michael S., Jung, Changhee, Ravi, Sekharipuram Subramaniam, Ravindran, Binoy |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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