Using formal methods to model hybrid manufacturing processes

Research on a planning method for switching moments in hybrid manufacturing processes

Formal methods encompass a wide choice of techniques and tools for the specification, development, analysis, and verification of software and hardware systems. Formal methods are widely applied in industry, in activities ranging from the elicitation of requirements and the early design phases all the way to the deployment, configuration, and runtime monitoring of actual systems. Formal methods allow one to precisely specify the environment in which a system operates, the requirements and properties that the system should satisfy, the models of the system used during the various design steps, and the code embedded in the final implementation, as well as to express conformance relations between these specifications. We present a broad scope of successful applications of formal methods in industry, not limited to the well-known success stories from the safety-critical domain, like railways and other transportation systems, but also covering other areas such as lithography manufacturing and cloud security in e-commerce, to name but a few. We also report testimonies from a number of representatives from industry who, either directly or indirectly, use or have used formal methods in their industrial project endeavours. These persons are spread geographically, including Europe, Asia, North and South America, and the involved projects witness the large coverage of applications of formal methods, not limited to the safety-critical domain. We thus make a case for the importance of formal methods, and in particular of the capacity to abstract and mathematical reasoning that are taught as part of any formal methods course. These are fundamental Computer Science skills that graduates should profit from when working as computer scientists in industry, as confirmed by industry representatives.

The aim of the study is to develop a theoretical approach for determining the parameters of a vibration device with asymmetric oscillations intended for hybrid manufacturing processes that combine additive wire deposition and conventional machining. An additional objective is to determine the optimal ratio of the components of the driving force acting in the directions of useful motion and idle motion using Fourier series coefficients obtained from the decomposition of a piecewise-smooth function. Materials and methods. The study employs analytical mathematical modeling methods based on Fourier series theory to describe polyharmonic vibration processes. A piecewise-smooth function representing the shape of a force impulse in a vibration system was used as the base function. The function was decomposed into a Fourier series with the determination of coefficients for trigonometric components. Subsequently, the inverse problem of synthesizing the total vibration signal with a minimal number of harmonic components was solved. Based on the obtained coefficients, a calculation procedure for the parameters of the vibration device was developed, including determination of the amplitudes of driving forces, rotational speeds of imbalance shafts, and masses of eccentric elements for individual vibration stages. Results and discussion. It was established that the use of asymmetric oscillations makes it possible to generate vibration effects with a specified asymmetry coefficient of the driving force, ensuring different amplitudes of force impulses acting in the directions of useful work and idle motion. The synthesis of oscillations based on Fourier series enables the formation of a total driving force in the form of a polyharmonic impulse composed of several synchronized vibration stages. Numerical parameters of vibration devices with different numbers of stages were obtained, allowing the implementation of the required asymmetry coefficient values. The proposed methodology makes it possible to determine the design parameters of vibrators, including imbalance masses, eccentricities, and rotational frequencies. Conclusion. The conducted research confirmed the feasibility of designing vibration devices with asymmetric oscillations using analytical synthesis of force impulses based on Fourier series coefficients. The proposed approach allows the formation of a predetermined ratio of the driving force components and determination of the structural parameters of vibration systems intended for hybrid manufacturing technologies. Proposals for practical application and direction of future research. The developed method can be applied in the design of vibration systems used in additive and hybrid manufacturing processes, including wire deposition, machining, and vibration-assisted material transport. Future research will focus on experimental validation of the proposed methodology, optimization of asymmetric oscillation parameters for various technological regimes, and the development of adaptive control systems for vibration devices.

Formal methods in Computer Science are a particular kind of mathematically-based techniques for the specification, development and verification of software and hardware systems. Among them, Petri Nets have been widely used because of their high expressive power and accurate description capabilities. On the other hand, Dynamical Systems theory has not been used for these purposes so far. In this paper we present the first use of Discrete Dynamical Systems under the aim to better analyze Concurrent Computing Systems. In order to do that, Petri Nets, PNs, are properly encoded into DDSs, so defining the corresponding Phase Space with its metric structure and the evolution operator of the system.

Iterative hybrid manufacture of a titanium alloy component

Abstract. This review or research paper is illustrated to analytically assess and address one of potential industrial revolutions, which is Wire Arc Additive Manufacturing (WAAM). WAAM is classified from Hybrid Manufacturing (HM) processes. Thus, one of the Hybrid Manufacturing ultimate goals has always been to transcend the limitation aspects associated with the tradition process. As Artificial Intelligence (AI) has evolved and expanded all over the globe, Additive Manufacturing (AM) has been gradually developed and introduced to the world to be one of a distinguished innovative impact in the history of manufacturing. Additive Manufacturing (AM) has been improved over the conventional methods in the manufacturing world due to its advanced complexity, consistency, quality of work, and various advantages and contribution that satisfy the costumers needs and requirements. Various applications in the industry have proven the AM applicability to replace the conventional processes such as casting and machining as it can deal with very coplex shapes [3]. In spite of the fact that there are numerous materials that can be manufactured in the modern technologies of AM, such as polymers, metals, ceramic, and composites, the contribution of Metal Additive Manufacturing (MAM) arguably has been a significant influence in the industries in comparison to the others [1]. In this review paper the detailed deliverable information and materials which will be established and communicated in this paper will concentrate on the history of (WAAM) including its pros and cons, latest contribution to the industries, AM classifications, materials, and primary materials and practices in industry.

Many critical control systems are developed using formal methods. When software applied to such systems is developed, the employment of formal methods in the software requirements specification and verification will provide increased assurance for such applications. Earlier error of overlooked requirement specification can be detected using formal specification method. Also the testing and full verification to examine all reachable states using model checking to undertake formal verification are able to be completed. In this paper, we proposed an eclectic approach to incorporate Z(Zed) formal language and ‘Statemate MAGNUM’ which is formal method tools using Statechart. Also we applied the proposed method to safety-critical railway signaling systems for the formal requirement specification and analyzed the specification results.

This document is intended to contribute to the area of validation and verification of communicating real time systems, with emphasis put on parametric reachability analysis of systems modeled using timed automata.Reachability analysis is a crucial aspect of validation and verification of software and hardware systems. The reachability analysis for real time systems is area that is studied by many researchers in academic and industrial communities. However, not much work has been done for systems, where time constraints are expressed using parameters. This is serious disproportion with real world, where specifications of most of the communication protocols or embedded software and hardware systems are indeed parameterized.This thesis presents a complete framework for forward and backward parametric reachability analysis. The solution presented here can be used as a base of algorithms for validation and verification of software and hardware real-time systems, modeled as timed automata with parameters. The results of the thesis can be easily applied to model checking or test generation tools and algorithms.The core idea of the thesis is a concept of Extended Difference Bound Matrix (EDBM). This is a data structure that stores relations between all system"s clocks and parameters. In contrast to Parametric DBM, that is the state-of-the-art data structure for parametric analysis, EDBM does not require storing constraints on clocks and constraints on parameters separately. This leads to significant benefits regarding memory consumption and time necessary to perform basic operations for symbolic analysis.The maturity of the solution was proven by implementation of a proof-of-concept tool and by experiments performed with modern communication protocol. The results show that even complex systems can be efficiently handled by the framework.

My new colleague has artificial muscles: a DEA based approach for inherently compliant robotic systems

Nanometer-scale structures suitable for computing have been investigated by several research groups in recent years. A common feature of these structures is their dynamic evolution through cascaded local interactions embedded on a discrete grid. Finding configurations capable of conducting computations is a task that often requires tedious experiments in laboratories. Formal methods—though used extensively for the specification and verification of software and hardware computing systems—are virtually unexplored with respect to computational structures at atomic scales. This paper presents a systematic approach toward the application of formal methods in this context, using techniques like abstraction, model-checking, and symbolic representations of states to explore and discover computational structures. The proposed techniques are applied to a system of CO molecules on a grid of Copper atoms, resulting in the design of a complete library of combinational logic gates based on this molecular system. The techniques are also applied on (more general) systems of cellular automata that employ an asynchronous mode of timing. The use of formal methods may narrow the gap between Physical Chemistry and Computer Science, allowing the description of interactions of nanometer scale systems on a level of abstraction suitable to devise computing devices.

This research introduces a low-cost, single-platform hybrid manufacturing process for realizing canonical and wideband antenna structures. This work outlines the printing processes of thick dielectrics & thin metallic geometries in coordination with selective removal of planar copper structures and provides a proof-of-concept demonstration of the first hybrid manufactured RF structures. Using the outlined processes, demonstration of a 6 GHz inset feed patch antenna and a Vivaldi antenna array prototype are presented first of their kind approach to realizing RF passives.

This volume contains the proceedings of Infinity'12, the 14th International Workshop on Verification of Infinite-State Systems, which was held in Paris, France on the 27th of August 2012 as a satellite event of FM'12. The aim of the INFINITY workshop is to provide a forum for researchers interested in the development of formal methods and algorithmic techniques for the analysis of systems with infinitely many states, and their application in automated verification of complex software and hardware systems.

The verification of control system software is critical to a host of technologies and industries, from aeronautics and medical technology to the cars we drive. The failure of controller software can cost people their lives. This book provides control engineers and computer scientists with an introduction to the formal techniques for analyzing and verifying this important class of software. Too often, control engineers are unaware of the issues surrounding the verification of software, while computer scientists tend to be unfamiliar with the specificities of controller software. The book provides a unified approach that is geared to graduate students in both fields, covering formal verification methods as well as the design and verification of controllers. It presents a wealth of new verification techniques for performing exhaustive analysis of controller software. These include new means to compute nonlinear invariants, the use of convex optimization tools, and methods for dealing with numerical imprecisions such as floating point computations occurring in the analyzed software. As the autonomy of critical systems continues to increase—as evidenced by autonomous cars, drones, and satellites and landers—the numerical functions in these systems are growing ever more advanced. The techniques presented here are essential to support the formal analysis of the controller software being used in these new and emerging technologies.

Sustaining weapons system hardware and software represents a significant and ever-increasing portion of total system cost. Hardware components are becoming obsolete much sooner while weapons system lifetimes are increasing, We must identify more cost-effective solutions to engineering and reengineering these subsystems. Verifying and validating weapons systems are two of the most costly parts of either engineering process. Traditionally, hardware validation and verification is done by simulation and testing, In the past few years, math- and logic-based formal methods tools have begun to scale up to and be applied successfully to real-world problems. Incorporating formal verification methods into engineering and reengineering processes will cost-effectively and significantly improve the level of trust and the quality of our weapons systems. Formal methods are especially well suited for redesigning current weapon systems which have become unsupportable due to component obsolescence because they help minimize the astronomical costs of rigorously reverifying the reengineered components. We believe that formal methods are an important tool for effective engineering of future weapon systems.

Formal methods tools have greatly influenced our ability to increase the reliability of software and hardware systems by revealing errors and clarifying critical concepts. In this article, we show how a rich specification language and a theorem prover for it have contributed to the design and implementation of verifiably correct adaptive protocols. The protocol-building team included experts in formal methods who were able to use the theorem prover to help guide protocol construction at the pace of implementation that is not formally assisted. This example shows that formal methods can have a large impact when being engaged at the earliest stages of design and implementation, because they add value to all subsequent stages, including the creation of informative documentation needed for the maintenance and evolution of software.