Joao Edgar Chaves Filho

DSVerifier: A Bounded Model Checking Tool for Digital Systems

This work presents the Digital-Systems Verifier DSVerifier, which is a verification tool developed for digital systems. In particular, DSVerifier employs the bounded model checking technique based on satisfiability modulo theories SMT solvers, which allows engineers to verify the occurrence of design errors, due to the finite word-length approach employed in fixed-point digital filters and controllers. This tool consists in an additional module for the efficient SMT-based context-bounded model checker and presents command-line and graphical user interface GUI versions. Indeed, the GUI version is essential for reporting property violations, together with associated counterexamples. DSVerifier is implemented in C/C

Formal Non-Fragile Stability Verification of Digital Control Systems with Uncertainty

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Designing an extension API for bridging Ginga iDTV applications and home services

and uses JavaFX for providing GUI support.

SMT-based Verification Applied to Non-convex Optimization Problems

Among the most promising applications provided by interactive digital television systems (iDTV) are the ones that enable TV-sets to work as the central processing unit of a house. This is supported by the extending of iDTV common functionalities making use of its processing power not only to deal with image and audio but also to execute interactive software applications. This paper proposes a new infrastructure that allows the exchange of data from the iDTV to home automation devices, such as sensors, mobile devices, and so on. The integration process among the involved technologies as well as each element in the proposed infrastructure is described in details. This model is supported by open services gateway initiative (OSGi), as a framework for networked devices, and the Brazilian reference middleware, Ginga. Thus it is possible to use devices services in OSGi-based home networks, through the digital TV. In order to prove the model functionalities, we created validating scenarios of service management involving iDTV interaction with mobile phones and electronic sensor devices using WiFi and Bluetooth technologies.

Robust decentralized controller for minimizing coupling effect in single inductor multiple output DC-DC converter operating in continuous conduction mode

A verification methodology is described and evaluated to formally determine uncertain linear systems stability in digital controllers with considerations to the implementation aspects. In particular, this methodology is combined with the digital-system verifier (DSVerifier), which is a verification tool that employs Bounded Model Checking based on Satisfiability Modulo Theories to check the stability of digital control systems with uncertainty. DSVerifier determines the control system stability, considering all the plant interval variation set, together with the Finite Word-length (FWL) effects in the digital controller implementation; DSVerifier checks the robust non-fragile stability of a given closed-loop system. The proposed methodology and respective tool are evaluated considering non-fragile control examples from literature. Experimental results show that the approach used in this study is able to foresee fragility problems in robust controllers, which could be overlooked by other existing approaches due to underestimating of FWL effects.

Counterexample guided inductive optimization based on satisfiability modulo theories

Digital controllers have several advantages with respect to their flexibility and designs simplicity. However, they are subject to problems that are not faced by analog controllers. In particular, these problems are related to the finite word-length implementation that might lead to overflows, limit cycles, and time constraints in fixed-point or floating-point processors. This paper proposes a new method to detect designs errors in fixed-point digital controllers using a state-of-the art bounded model checker based on satisfiability modulo theories. The experiments with a commercial plant demonstrate that the proposed method can be effective in finding errors in digital controllers than other existing approaches, which are based on traditional simulations tools. The verification results are conclusive in 93.5% of the benchmarks, determining the absence or occurrence of errors.

Dynamic and automated product derivation for consumer electronics software applications

This paper presents the implementation process for an API that integrates interactive digital TV (iDTV) applications and home network (HN) services, mainly concerning issues of the Brazilian iDTV model. The research in this field is important because it represents current trends on the use of iDTV opening many business opportunities. With the convergence of service providers, modern communication technologies and consumer electronics devices at home, new iDTV applications have emerged, particularly those that use the set-top-boxes (or digital TV sets) processing power to provide additional services, which extends the possibilities of interaction between the user and the connected home. To implement this platform, a known model, which considers aspects of the Ginga middleware and the Open Services Gateway Initiative (OSGi) framework, was used. The idea behind the API model is to export service objects from one side to another, allowing the development of two types of applications: the first one on the Ginga-J machine and the last one on the Ginga-NCL machine. The main goals of this paper are (i) presenting the use of free tolls to perform such integration and (ii) showing the most relevant aspects in the core of the two models. Finally, a basic step-by-step process is shown in order to build integrated iDTVHN real applications using this platform.

Using a random restart hill-climbing algorithm to reduce component assembly time in printed circuit boards

This paper presents a novel, complete, and flexible optimization algorithm, which relies on recursive executions that re-constrains a model-checking procedure based on Satisfiability Modulo Theories (SMT). This SMT-based optimization technique is able to optimize a wide range of functions, including non-linear and non-convex problems using fixed-point arithmetic. Although SMT-based optimization is not a new technique, this work is the pioneer in solving non-linear and non-convex problems based on SMT; previous applications are only able to solve integer and rational linear problems. The proposed SMT-based optimization algorithm is compared to other traditional optimization techniques. Experimental results show the efficiency and effectiveness of the proposed algorithm, which finds the optimal solution in all evaluated benchmarks, while traditional techniques are usually trapped by local minima.