Analysis Of Real-time Properties Research Articles

Modeling and Analysis of Real-time Properties of Open Architecture Computerized Numerical Control Systems

A novel modeling method called timed transition model/all-time real-time temporal logic(TTM/ATRTTL) for specifying open architecture CNC(OAC) systems is proposed.TTM/ATRTTL provides full support for specifying hard real-time property and feed-back characteristics needed for modeling OAC systems.The formal method is used to model OAC systems from different aspects by specifying the TTM structure of an open-loop OAC,a system-level logic controller,and task communication and synchronization,and obtain the closed-loop OAC TTM with scheduling mechanism is given,which is the foundation of the verification framework.Finally,a verification framework is proposed and implemented with STeP and SF2STeP.In the verification,several problems are solved including rewrite rule,verification rule,state explosion problem,and time bound restriction when STeP is used for verification,and then experiments are conducted for verifying an OAC system for dead-lock and system time bound checking.The results show that the method can effectively model and verify OAC systems.

Predictable real-time software synthesis

Formal theories for real-time systems (such as timed process algebra, timed automata and timed petri nets) have gained great success in the modeling of concurrent timing behavior and in the analysis of real-time properties. However, due to the ineliminable timing differences between a model and its realization, synthesizing a software realization from a model in a predictable way is still a challenging research topic. In this article, we tackle this problem by solving a set of sub-problems. The solution is based on the theoretical results for property prediction proposed in Huang et al. (2003, Real-time property preservation in approximations of timed systems. In: Proceedings of 1st ACM and IEEE international conference on formal methods and models for codesign. IEEE Computer Society, Los Alamitos, pp 163–171) and Huang (2005, Predictability in real-time system design. PhD thesis, Eindhoven University of Technology, The Netherlands), where quantitative property relations are established between two absolute/relative “close” real-time systems. This theory basically implies that if two systems are “close”, they enjoy “similar” properties. These results cannot be directly applied in practice though, because a model and its realization typically have infinitely large absolute and relative timing differences. We show that this infinite time gap can be bridged through a sequence of carefully constructed intermediate time domains. Then the property-prediction results can be applied to any pair of adjacent time domains in the sequence. Consequently, real-time properties of the implementation can be predicted from the model. We propose two parameterized hypotheses to characterize the timing differences in the sequence and to guide a correctness-preserving design process. It is shown that these hypotheses can be incorporated in a concrete tool set. We demonstrate the feasibility of the predictable synthesis approach through the design of a railroad crossing system.

Analysis of real-time properties and rules for setting protocol parameters of MAP networks

This paper reports on an evaluation of real-time properties of MAP (Manufacturing Automation Protocol) networks by analytical considerations and measurements. Based on a model of the time schedule of a communication cycle figures for response times (transport system) and message delays (MAC layer) are given. The influence of some options for handling acknowledgments within the transport layer is shown. The message delay at MAC layer is separated into an implementation-dependent and a protocol-dependent protion, and an upper bound is derived. Rules for selecting protocol parameters affecting real time behavior are given. Aspects for improved implementations of communication controllers for MAP networks are discussed.