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Stavros Tripakis - One of the best experts on this subject based on the ideXlab platform.
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mechanically proving determinacy of hierarchical Block diagram translations
Verification Model Checking and Abstract Interpretation, 2019Co-Authors: Viorel Preoteasa, Iulia Dragomir, Stavros TripakisAbstract:Hierarchical Block Diagrams (HBDs) are at the heart of embedded system design tools, including Simulink. Numerous translations exist from HBDs into languages with formal semantics, amenable to formal verification. However, none of these translations has been proven correct, to our knowledge.
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Type Inference of Simulink Hierarchical Block Diagrams in Isabelle
2017Co-Authors: Viorel Preoteasa, Iulia Dragomir, Stavros TripakisAbstract:Simulink is a de-facto industrial standard for embedded system design. In previous work, we developed a compositional analysis framework for Simulink, the Refinement Calculus of Reactive Systems (RCRS), which allows checking compatibility and substitutability of components. However, standard type checking was not considered in that work. In this paper we present a method for the type inference of Simulink models using the Isabelle theorem prover. A Simulink diagram is translated into an (RCRS) Isabelle theory. Then Isabelle’s powerful type inference mechanism is used to infer the types of the diagram based on the types of the basic Blocks. One of the aims is to handle formally as many Diagrams as possible. In particular, we want to be able to handle even those Diagrams that may have typing ambiguities, provided that they are accepted by Simulink. This method is implemented in our toolset that translates Simulink Diagrams into Isabelle theories and simplifies them. We evaluate our technique on several case studies, most notably, an automotive fuel control system benchmark provided by Toyota.
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compositional semantics and analysis of hierarchical Block Diagrams
International Symposium on Model Checking Software, 2016Co-Authors: Iulia Dragomir, Viorel Preoteasa, Stavros TripakisAbstract:We present a compositional semantics and analysis framework for hierarchical Block Diagrams (HBDs) in terms of atomic and composite predicate transformers. Our framework consists of two components: (1) a compiler that translates Simulink HBDs into an algebra of transformers composed in series, in parallel, and in feedback; (2) an implementation of the theory of transformers and static analysis techniques for them in Isabelle. We evaluate our framework on several case studies including a benchmark Simulink model by Toyota.
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Efficient distribution of Triggered Synchronous Block Diagrams on asynchronous platforms
2015 International Conference on Embedded Computer Systems: Architectures Modeling and Simulation (SAMOS), 2015Co-Authors: Yang Yang, Stavros Tripakis, Alberto Sangiovanni-vincentelliAbstract:As the complexity of embedded systems rapidly increases in terms of both scale and functionality, there has been a strong interest in design languages and methodologies that facilitate the use of formal methods. These languages and methodologies are mostly based on a synchronous paradigm that, while satisfies the need for formalization, often results in an inefficient implementation requiring substantial overhead when compared to approaches that do not enforce synchronicity on the execution platform. Therefore, the interest is high for techniques that on one hand, maintain the formal properties of synchronous models, and on the other hand, enable the use of asynchronous and distributed execution platforms with little overhead. In this paper, we propose an approach for efficient distribution of Triggered Synchronous Block Diagrams (SBDs) on asynchronous platforms while preserving the correct semantics. Compared to previous work that utilizes trigger elimination, our approach aims to reduce the unnecessary communication overhead and thus improve the efficiency of the implementation. We consider both general Triggered SBDs where the values of triggers are dynamically computed, as well as Timed SBDs where triggers are statically known and usually specified by (period, initial phase) pairs.
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efficient distribution of triggered synchronous Block Diagrams
2011Co-Authors: Yang Yang, Stavros Tripakis, Alberto SangiovannivincentelliAbstract:Abstract : Most of the design challenges for complex cyber-physical systems, where a digital controller governs a multiphysics plant, relate to the distributed nature of the systems to be controlled. Cars, airplanes, and power distribution grids are well-known examples. The characteristics of the communication network that connects the system components affect the derivation of the control law and the verification of design correctness. For this reason, there has been a strong interest in using languages and methodologies that facilitate the use of formal methods. These languages and methodologies are mostly based on a synchronous paradigm that, while satisfies the need for formalization, often results in an inefficient implementation requiring substantial overhead when compared to approaches that do not enforce synchronicity on the execution platform. Therefore, the interest is high for techniques that on one hand maintain the formal properties of synchronous models, and on the other hand, enable the use of asynchronous and distributed execution platforms with little overhead. In this paper we address the problem of automatic synthesis, and in particular automatic and semantics-preserving implementation of Triggered Synchronous Block Diagrams (SBDs) on distributed, asynchronous execution platforms. This problem was studied for pure SBDs (where all Blocks are triggered in every synchronous step) in [23]. The method of [23] can be adapted to Triggered SBDs by using trigger elimination [16], where triggers are transformed to standard inputs. However, this often results in unnecessary communication overhead. In this paper we propose methods to minimize this overhead, thus improving the efficiency of the approach. We consider both general Triggered SBDs where the values of triggers are dynamically computed and are thus not known a-priori, as well as Timed SBDs where triggers are statically known, usually specified by (period, initial phase) pairs.
G Wszolek - One of the best experts on this subject based on the ideXlab platform.
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vibration analysis of the excavator model in grafsim program on the basis of a Block diagram method
Journal of Materials Processing Technology, 2004Co-Authors: G WszolekAbstract:Abstract In this article a numerical vibration analysis of the excavator model is presented. This model with a discrete distribution of the parameters, shown in three working positions, is attracted to kinematic and dynamic excitations. The analysis is made in GRAFSIM program, which was intended and prepared for projecting and analysing 2D and 3D mechanical systems with linear couplings. The program works on the basis that the algorithm transforms matrix hybrid graph model structures into Block Diagrams structures [G. Wszolek, Hybrid graphs and Block Diagrams in analysing mechanical systems with control, Doctoral Thesis, Silesian University of Technology, Gliwice, Poland, 2002 (in polish); J. Świder, G. Wszolek, Graphs application in computer analysis of mechanical systems, Monograph, Silesian University Publishing Company, Gliwice, Poland, 2002 (in polish)]. The time and frequency responses from the examined mechanical system are presented.
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vibration analysis software based on a matrix hybrid graph transformation into a structure of a Block diagram method
Journal of Materials Processing Technology, 2004Co-Authors: J świder, G WszolekAbstract:Abstract In this article a program called GRAFSIM, implemented in the MATLAB-SIMULINK software environment, is presented. It realises a transformation of matrix hybrid graphs to a Block Diagrams method and enables to prepare comprehensive and complex analysis of two- and three-dimensional mechanical systems with lineal couplings.
Pieter J Mosterman - One of the best experts on this subject based on the ideXlab platform.
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extensible discrete event simulation framework in simevents
Winter Simulation Conference, 2016Co-Authors: Ramamurthy Mani, Pieter J MostermanAbstract:A simulation framework is introduced that facilitates hierarchical definition and composition of discrete-event systems. This framework enables modelers to flexibly use graphical Block Diagrams, state charts, and MATLAB textual object-oriented programming to author custom domain-specific discrete-event systems. The framework has been realized in an implementation that spans multiple software simulation tools including SimEvents, Stateflow, Simulink and MATLAB.
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stream and state based semantics of hierarchy in Block Diagrams
IFAC Proceedings Volumes, 2008Co-Authors: Ben Denckla, Pieter J MostermanAbstract:Abstract Block Diagrams are often used in embedded system design for modeling both plant and controller, typically with continuous and discrete modeling, respectively. Though easy to use, advanced users and implementers of these languages often run afoul of subtle semantic problems these seemingly simple languages can have. Based on the stream- and state-based approaches, this paper discusses how the specialized state-based semantics of continuous-time Block Diagrams can interoperate hierarchichally with discrete-time Block Diagrams. The languages presented may serve as a reference of sorts, helping to clarify some of the underlying choices in Block diagram language design, and in the process shedding light on the differences between, and limitations of, existing Block diagram languages.
Liudong Xing - One of the best experts on this subject based on the ideXlab platform.
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formal semantics and verification of dynamic reliability Block Diagrams for system reliability modeling
International Conference on Software Engineering, 2007Co-Authors: Liudong XingAbstract:With the rapid advances in computer science and technology, critical computer-based systems, such as those in aerospace, military, and power industries exhibit more complex dependent and dynamic behaviors, which cannot be fully captured by existing reliability modeling tools. In this paper, we introduce a new reliability modeling tool, called dynamic reliability Block Diagrams (DRBD), for modeling dynamic relationships between components, such as state dependency and redundancy. We give formal semantics for some key DRBD constructs using Object-Z formalism. In order to verify and validate the correctness of a DRBD model, we propose to convert a DRBD model into a colored Petri net (CPN), and use an existing Petri net tool, called CPN Tools, to analyze and verify dynamic system behavioral properties. Our case study and experimental results show that DRBD provides a powerful tool for system reliability modeling, and our proposed verification approach can effectively ensure the correct design of DRBD reliability models for complex and large-scale computer-based systems.
Denis Royston Towill - One of the best experts on this subject based on the ideXlab platform.
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a discrete transfer function model to determine the dynamic stability of a vendor managed inventory supply chain
International Journal of Production Research, 2002Co-Authors: Stephen Michael Disney, Denis Royston TowillAbstract:This paper considers a well-established production and distribution scheduling algorithm, called the Automatic Pipeline, Inventory and Order Based Production Control System (APIOBPCS) within a Vendor Managed Inventory (VMI) supply chain. It develops a transfer function model of the system using causal loop Diagrams, Block Diagrams, difference equations and z -transforms. Important insights into the VMI supply chain are derived from the mathematical model pertaining to the stability and robustness of the VMI system. Analysis confirmed by dynamic simulation clearly demonstrates instability arising from poor design. We also demonstrate its avoidance via our recommended parameter settings for tuning the two feedback loops within the supply chain for a specific production delay. The procedure is readily extended for other production delays and distributions.
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a discrete transfer function model to determine the dynamic stability of a vendor managed inventory supply chain
International Journal of Production Research, 2002Co-Authors: Stephen Michael Disney, Denis Royston TowillAbstract:This paper considers a well-established production and distribution scheduling algorithm, called the Automatic Pipeline, Inventory and Order Based Production Control System (APIOBPCS) within a Vendor Managed Inventory (VMI) supply chain. It develops a transfer function model of the system using causal loop Diagrams, Block Diagrams, difference equations and z -transforms. Important insights into the VMI supply chain are derived from the mathematical model pertaining to the stability and robustness of the VMI system. Analysis confirmed by dynamic simulation clearly demonstrates instability arising from poor design. We also demonstrate its avoidance via our recommended parameter settings for tuning the two feedback loops within the supply chain for a specific production delay. The procedure is readily extended for other production delays and distributions. View Full Text Article
