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Unlike standalone embedded devices, behaviors of a cyber-physical system (CPS) are highly dynamic. Many parameter values (e.g., those related to nature environment and third party black box functions) are unknown offline. Furthermore, distributed sub-CPSs may exchange data online. In this article, we first propose the concept of parametric hybrid automata (PHA) to describe such complex CPSs. As some PHA parameter values are unknown until runtime, conventional offline model checking is infeasible. Instead, we propose to carry out PHA model checking online, as a fault prediction mechanism. However, this usage is challenged by the high time cost of state reachability verification, which is the conventional focus of model checking. To address this challenge, we propose that the model checking shall focus on online scenario reachability validation instead. Furthermore, we propose a mechanism to compose/decompose scenarios. Our scenario reachability validation can exploit linear programming to achieve polynomial time cost. Evaluations on a state-of-the-art train control system show that our approach can cut online model checking time cost from over 1 h to within 200 ms. [ABSTRACT FROM AUTHOR]

Networked robotics are a typical cyber–physical system (CPS). This paper presents the cyber physical interaction model to perform formation control and tracking in the presence of other robots and static obstacles. It discusses how such a model can be effectively utilized to deal with kinodynamic and operation range constraints. The cyber system is also responsible for feasible trajectory generation based upon regional path segments and to ensure that all the robots maneuver through obstacles in a safe manner. The introduction of virtual robot restructures the formation control problem into a tracking control problem between virtual reference robot and follower robots. A novel obstacle avoidance approach is proposed based upon the scaling of whole (partial) formation corresponding to centralized (distributed) framework. The involved CPS has network structure preserving properties that are key to effective distributed decision making. The novel formation control, obstacle avoidance, and trajectory tracking approaches facilitate networked robots to be effectively controlled through the cyber system. We also discuss efficient and optimal implementation of the proposed trajectory generator using computer-aided design for CPSs. Evaluation of the proposed approach is provided that demonstrate the formation control, trajectory tracking, and obstacle avoidance for multirobots using the proposed scheme. [ABSTRACT FROM AUTHOR]

Cyber-Physical Systems (CPS) integrate discrete-time computing and continuous-time physical-world entities, which are often wirelessly interlinked. The use of wireless safety-critical CPS requires safety guarantees despite communication faults. This paper focuses on one important set of such safety rules: Proper-Temporal-Embedding (PTE), where distributed CPS entities must enter/leave risky states according to properly nested temporal pattern and certain duration spacing. Our solution introduces hybrid automata to formally describe and analyze CPS design patterns. We propose a novel leasing based design pattern, along with closed-form configuration constraints, to guarantee PTE safety rules under arbitrary wireless communication faults. We propose a formal procedure to transform the design pattern hybrid automata into specific wireless CPS designs. This procedure can effectively isolate physical world parameters from affecting the PTE safety of the resultant specific designs. We conduct two wireless CPS case studies, one on medicine and the other on control, to show that the resulted system is safe against communication failures. We also compare our approach with a polling based approach. Both approaches support PTE under arbitrary communication failures. The polling approach performs better under severely adverse wireless medium conditions; while ours performs better under benign or moderately adverse wireless medium conditions. [ABSTRACT FROM AUTHOR]