Thanh-Hung Nguyen

Rigorous Component-Based System Design Using the BIP Framework

An autonomous robot case study illustrates the use of the behavior, interaction, priority (BIP) component framework as a unifying semantic model to ensure correctness of essential system design properties.

D-Finder: A Tool for Compositional Deadlock Detection and Verification

D-Finder tool implements a compositional method for the verification of component-based systems described in BIP language encompassing multi-party interaction. For deadlock detection, D-Finder applies proof strategies to eliminate potential deadlocks by computing increasingly stronger invariants.

Runtime verification of component-based systems

Verification of component-based systems still suffers from limitations such as state space explosion since a large number of different components may interact in an heterogeneous environment. Those limitations entail the need for complementary verification methods such as runtime verification based on dynamic analysis and prone to scalability. In this paper, we integrate runtime verification into the BIP (Behavior, Interaction, and Priority) framework. BIP is a powerful component-based framework for the construction of heterogeneous systems. Our method augments BIP systems with monitors checking a user-provided specification. This method has been implemented in RV-BIP, a prototype tool that we used to validate the whole approach on a robotic application.

D-finder 2: towards efficient correctness of incremental design

D-Finder 2 is a new tool for deadlock detection in concurrent systems based on effective invariant computation to approximate the effects of interactions among modules. It is part of the BIP framework, which provides various tools centered on a component-based language for incremental design. The presented tool shares its theoretical roots with a previous implementation, but was completely rewritten to take advantage of a new version of BIP and various new results on the theory of invariant computation. The improvements are demonstrated by comparison with previous work and reports on new results on a practical case study.

Runtime verification of component-based systems in the BIP framework with formally-proved sound and complete instrumentation

Verification of component-based systems still suffers from limitations such as state space explosion since a large number of different components may interact in a heterogeneous environment. These limitations entail the need for complementary verification methods such as runtime verification. Runtime verification is a dynamic analysis technique and is prone to scalability. In this paper, we integrate runtime verification into the BIP (Behavior, Interaction and Priority) framework. BIP is a powerful and expressive component-based framework for the formal construction of heterogeneous systems. Our method augments BIP systems with monitors to check specifications at runtime. This method has been implemented in RV-BIP, a prototype tool that we used to validate the whole approach on a robotic application.

Efficient deadlock detection for concurrent systems

Concurrent systems are prone to deadlocks that arise from competing access to shared resources and synchronization between the components. At the same time, concurrency leads to a dramatic increase of the possible state space due to interleavings of computations, which makes standard verification techniques often infeasible. Previous work has shown that approximating the state space of component based systems by computing invariants allows to verify much larger systems then standard methods that compute the exact state space. The approach comes with the drawback, though, that not all of the reported specification violations may be reachable in the system. This paper deals with that problem by combining the information from the invariant with model checking techniques and strategies for reducing the memory footprint. The approach is implemented as post processing step for generating the exact set of reachable specification violations along with traces to demonstrate the error.

Component-based verification using incremental design and invariants

We propose invariant-based techniques for the efficient verification of safety and deadlock-freedom properties of component-based systems. Components and their interactions are described in the BIP language. Global invariants of composite components are obtained by combining local invariants of their constituent components with interaction invariants that take interactions into account. We study new techniques for computing interaction invariants. Some of these techniques are incremental, i.e., interaction invariants of a composite hierarchically structured component are computed by reusing invariants of its constituents. We formalize incremental construction of components in the BIP language as the process of building progressively complex components by adding interactions (synchronization constraints) to atomic components. We provide sufficient conditions ensuring preservation of invariants when new interactions are added. When these conditions are not satisfied, we propose methods for generating new invariants in an incremental manner by reusing existing invariants from the constituents in the incremental construction. The reuse of existing invariants reduces considerably the overall verification effort. The techniques have been implemented in the D-Finder toolset. Among the experiments conducted, we have been capable of verifying safety properties and deadlock-freedom of sub-systems of the functional level of the DALA autonomous robot. This work goes far beyond the capacity of existing monolithic verification tools.

A 3-D point clouds scanning and registration methodology for automatic object digitization

Abstract The article presents a robot 3-D scanning system for generation of 3-D point clouds of an object by using multi-view 3-D scanning and novel data registration. Our approach mainly comprises two important elements in the determination of next best probe pose and multiple-view point clouds registration. A novel technique is proposed to register 3-D object scene with overlapped or stacked condition. Under this scenario, conventional registration methods such as the iterative closest point algorithm usually fail to converge to a global minimum when a good initial estimate for image registration does not exist. Our proposed technique uses a 3-D scanner to be mounted on a six degree of freedom-articulated industrial robot. It keeps moving probe continuously in the working range against the object and autonomously varying the probe with various gestures required for complete object scanning and for achieving best 3-D sensing accuracy. The robot scanning path is determined through a proposed algorithm using information from the latest scanning data and registered result of the object. The developed method has been verified through experimental tests for its feasibility test. It confirms that the registration accuracy with one standard deviation can be controlled within 0.323 mm when the objects underlying reconstruction are in range of hundreds of millimeters.

Current medical product development for diagnosis, surgical planning and treatment in the areas of Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery in Vietnam

With the population of 86 million and good GDP growth in recent decades, the medical market in Vietnam is growing fast. However, most of the medical technology products are imported, and the number of locally manufactured ones is limited and they do not have the high competition capability in term of quality, quantity and types. In this paper, the current product development in Vietnam for diagnosis, surgical planning and treatment in the areas of Rehabilitation, Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery is presented. A roadmap for medical technology development in Vietnam is proposed.

Safe Incremental Design of UML Architectures.

IDF is an Incremental Development Framework which supports the development and the verification of UML models for concurrent and reactive systems. IDF offers refinement and extension techniques the goal of which is to check the preservation of liveness properties during the model developments. Here, we improve the framework in order to analyze models from a safety point of view. Some techniques such as refinement maintain safety properties, however, extension does not maintain such properties. For this purpose, we associate IDF with the experienced tools of safety analysis based on the BIP language by translating UML models into BIP. We demonstrate on a basic example the comple-mentarity of liveness and safety analyses.