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Real-time hybrid testing of civil structures represents a grand challenge in the emerging area of cyber-physical systems. Hybrid testing improves significantly on either purely numerical or purely empirical approaches by integrating physical structural components and computational models. Actuator dynamics, complex interactions among computers and physical components, and computation and communication delays all hamper the ability to conduct accurate tests. To address these challenges, this paper presents initial work towards a Cyber-physical Instrument for Real-time hybrid Structural Testing (CIRST). CIRST aims to provide two salient features: a highly configurable architecture for integrating computers and physical components; and system support for real-time operations in distributed hybrid testing. This paper presents the motivation of the CIRST architecture and preliminary test results from a proof-of-concept implementation that integrates a simple structural element and simulation model. CIRST will have broad impacts on the fields of both civil engineering and real-time computing. It will enable high-fidelity real-time hybrid testing of a wide range of civil infrastructures, and will also provide a high-impact cyber-physical application for the study and evaluation of real-time middleware.

Abstract

Abstract. Scheduling the execution of multiple concurrent tasks on shared resources such as CPUs and network links is essential to ensuring the reliable operation of many autonomic systems. Well known techniques such as rate-monotonic scheduling can offer rigorous timing and preemption guarantees, but only under assumptions (i.e., a fixed set of tasks with well-known execution times and invocation rates) that do not hold in many autonomic systems. New hierarchical scheduling techniques are better suited to enforce the more flexible execution constraints and enforcement mechanisms that are required for autonomic systems, but a rigorous foundation for verifying and enforcing concurrency and timing guarantees is still needed for these approaches. The primary contributions of this paper are: (1) a scheduling policy design technique that can use different decision models across a wide range of systems models, and an example of how a specific (Markov Decision Process) decision model can be applied to a basic multi-threaded system model; (2) novel model checking techniques that can evaluate the behavior of the system model when it is placed under the control of the resulting scheduling policy; and (3) an evaluation of those scheduling policy design and model checking techniques for a simple but representative example of the kinds of execution scenarios that can arise in autonomic systems.

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