Interoperability is a central problem in digitization and sos engineering, which concerns the capacity of systems to exchange information and cooperate. The task to dynamically establish interoperability between heterogeneous cps at run-time is a challenging problem. Different aspects of the interoperability problem have been studied in fields such as sos, neural translation, and agent-based systems, but there are no unifying solutions beyond domain-specific standardization efforts. The problem is complicated by the uncertain and variable relations between physical processes and human-centric symbols, which result from, e.g., latent physical degrees of freedom, maintenance, re-configurations, and software updates. Therefore, we surveyed the literature for concepts and methods needed to automatically establish sos with purposeful cps communication, focusing on machine learning and connecting approaches that are not integrated in the present literature. Here, we summarize recent developments relevant to the dynamic interoperability problem, such as representation learning for ontology alignment and inference on heterogeneous linked data; neural networks for transcoding of text and code; concept learning-based reasoning; and emergent communication. We find that there has been a recent interest in deep learning approaches to establishing communication under different assumptions about the environment, language, and nature of the communicating entities. Furthermore, we present examples of architectures and discuss open problems associated with ai-enabled solutions in relation to sos interoperability requirements. Although these developments open new avenues for research, there are still no examples that bridge the concepts necessary to establish dynamic interoperability in complex sos, and realistic testbeds are needed.

Interoperability in systems-of-systems is a difficult problem due to the abundance of data standards and formats. Current approaches to interoperability rely on hand-made adapters or methods using ontological metadata. This dataset was created to facilitate research on data-driven interoperability solutions. The data comes from a simulation of a building heating system, and the messages sent within control systems-of-systems. For more information see attached data documentation.

The data comes in two semicolon-separated (;) csv files, training.csv and test.csv. The train/test split is not random; training data comes from the first 80% of simulated timesteps, and the test data is the last 20%. There is no specific validation dataset, the validation data should instead be randomly selected from the training data. The simulation runs for as many time steps as there are outside temperature values available. The original SMHI data only samples once every hour, which we linearly interpolate to get one temperature sample every ten seconds. The data saved at each time step consists of 34 JSON messages (four per room and two temperature readings from the outside), 9 temperature values (one per room and outside), 8 setpoint values, and 8 actuator outputs. The data associated with each of those 34 JSON-messages is stored as a single row in the tables. This means that much data is duplicated, a choice made to make it easier to use the data.

The simulation data is not meant to be opened and analyzed in spreadsheet software, it is meant for training machine learning models. It is recommended to open the data with the pandas library for Python, available at https://pypi.org/project/pandasOpens in a new tab.

The data file with temperatures (smhi-july-23-29-2018.csv) acts as input for the thermodynamic building simulation found on Github, where it is used to get the outside temperature and corresponding timestamps. Temperature data for Luleå Summer 2018 were downloaded from SMHI. 

Datasetet innehåller simulerad servicedata för system-av-system interoperabilitetsforskning. För mer information se bifogad dokumentation och den engelska katalogsidan.

Data kommer i två semikolonseparerade (;) csv-filer, training.csv och test.csv. Träning/testfördelningen är inte slumpmässig; träningsdata kommer från de första 80 % av de simulerade tidsstegen och testdata är de sista 20 %. Det finns ingen specifik valideringsdatauppsättning, valideringsdatan bör istället väljas slumpmässigt från träningsdatan. Simuleringen körs i lika många tidssteg som det finns tillgängliga utetemperaturvärden. De ursprungliga SMHI-data samplar bara en gång i timmen, som linjärt interpolerar för att få ett temperaturprov var tionde sekund. Data som sparas vid varje tidssteg består av 34 JSON-meddelanden (fyra per rum och två temperaturavläsningar utifrån), 9 temperaturvärden (ett per rum och utanför), 8 börvärden och 8 ställdonutgångar. Data som är associerade med vart och ett av dessa 34 JSON-meddelanden lagras som en enda rad i tabellerna. Detta innebär att mycket data dupliceras, ett val som görs för att göra det lättare att använda datan.

Simuleringsdata är inte avsedd att öppnas och analyseras i kalkylprogram, det är avsett att träna maskininlärningsmodeller. Det rekommenderas att öppna data med pandas-biblioteket för Python, tillgängligt på https://pypi.org/project/pandasÖppnas i en ny tabb.

Datafil med temperaturer (smhi-july-23-29-2018.csv) för termodynamisk simulering avsedd som input vid simulering gällande utomhustemperatur och tidsmarkör. Temperaturdata från Luleå sommaren 2018 var nedladdade från SMHI. 

Interoperability in systems-of-systems is a difficult problem due to the abundance of data standards and formats.Current approaches to interoperability rely on hand-made adapters or methods using ontological metadata.This dataset was created to facilitate research on data-driven interoperability solutions.The data comes from a simulation of a building heating system, and the messages sent within control systems-of-systems. 

Industrial automation is transforming by ongoing digitalization efforts to create a flexible industrial internet of things, turning manufacturing facilities into large-scale systems of cyber-physical systems. This development requires addressing the challenging issue of making heterogeneous systems, data models, and standards interoperable, a core problem in designing sustainable service-oriented automation frameworks. This thesis reviews the problem of automatically establishing the interoperability of services exchanging heterogeneous message data. A machine-learning architecture is developed, where the optimization of message transcoders and the system of systems utility are mechanisms for establishing interoperability. By optimizing the transcoders using both service- and metadata, the aim is to ground the learned latent representations in the physical environment to improve generalization. Two physical simulation experiments were performed to investigate and evaluate the architecture by generating heterogeneous JSON messages from multiple heating and air conditioning services. The first experiment focuses on unsupervised learning via back-translation for transcoding engineered features of service messages, reaching a maximum translation accuracy of 49%. The second experiment focuses on supervised learning and a modular neural network (JSON2Vec) for automated encoding of the heterogeneous JSON messages, which enables correct message interpretation in terms of the expected system of systems behavior. These results suggest that machine learning is a viable direction in interoperability automation research which can benefit from both symbolic metadata and message data for reliable generalization and adaptation. Appropriate open datasets are required to consolidate the envisioned development and the migration of solutions to automation systems.

We formulate the challenging problem to establish information interoperability within a system of systems (SoS) as a machine-learning task, where autoencoder embeddings are aligned using message data and metadata to automate message translation. An SoS requires communication and collaboration between otherwise independently operating systems, which are subject to different standards, changing conditions, and hidden assumptions. Thus, interoperability approaches that are based on standardization and symbolic inference will have limited generalization and scalability in the SoS engineering domain. We present simulation experiments performed with message data generated using heating and ventilation system simulations. While the unsupervised learning approach proposed here remains unsolved in general, we obtained up to 75% translation accuracy with autoencoders aligned by back-translation after investigating seven different models with different training protocols and hyperparameters. For comparison, we obtain 100% translation accuracy on the same task with supervised learning, but the need for a labeled dataset makes that approach less interesting. We discuss possibilities to extend the proposed unsupervised learning approach to reach higher translation accuracy.

Modern large-scale automation systems integrate thousands to hundreds of thousands of physical sensors and actuators. Demands for more flexible reconfiguration of production systems and optimization across different information models, standards and legacy systems challenge current system interoperability concepts. Automatic semantic translation across information models and standards is an increasingly important problem that needs to be addressed to fulfill these demands in a cost-efficient manner under constraints of human capacity and resources in relation to timing requirements and system complexity. Here we define a translator-based operational interoperability model for interacting cyber-physical systems in mathematical terms, which includes system identification and ontology-based translation as special cases. We present alternative mathematical definitions of the translator learning task and mappings to similar machine learning tasks and solutions based on recent developments in machine learning. Possibilities to learn translators between artefacts without a common physical context, for example in simulations of digital twins and across layers of the automation pyramid are briefly discussed.

Increasingly flexible and efficient industrial processes and automation systems are developed by integrating computational systems and physical processes, thereby forming large heterogeneous systems of cyber-physical systems. Such systems depend on particular data models and payload formats for communication, and making different entities interoperable is a challenging problem that drives the engineering costs and time to deployment. Interoperability is typically established and maintained manually using domain knowledge and tools for processing and visualization of symbolic metadata, which limits the scalability of the present approach. The vision of next generation automation frameworks, like the Arrowhead Framework, is to provide autonomous interoperability solutions. In this thesis the problem to automatically establish interoperability between cyber-physical systems is reviewed and formulated as a mathematical optimisation problem, where symbolic metadata and message payloads are combined with machine learning methods to enable message translation and improve system of systems utility. An autoencoder based implementation of the model is investigated and simulation results for a heating and ventilation system are presented, where messages are partially translated correctly by semantic interpolation and generalisation of the latent representations. A maximum translation accuracy of 49% is obtained using this unsupervised learning approach. Further work is required to improve the translation accuracy, in particular by further exploiting metadata in the model architecture and autoencoder training protocol, and by considering more advanced regularization methods and utility optimization.

Semantic interoperability is the ability of systems to exchange information with unambiguous meaning. This is an outstanding challenge in the development of Industry 4.0 due to the trend towards dynamic re-configurable production processes with increasingly complex automation systems and a diversity of standards, components, tools and services. The cost of making systems interoperable is a major limiting factor in the adoption of new technology and the envisioned development of production industry. Therefore, methods and concepts enabling efficient interoperation of heterogeneous systems are investigated to understand how the interoperability problem should be addressed. To support this development, we survey the literature on interoperability to identify automation approaches that address semantic interoperability, in particular in dynamic cyber-physical systems at large scale. We find that different aspects of the interoperability problem are investigated, some based on a conventional bottom-up standardization approach, while others consider a goal-driven computational approach; and that the different directions explored are related to open questions that motivates further research. We argue that a goaldriven machine learning approach to semantic interoperability can result in solutions that are applicable across standardization domains and thus is a promising direction of research in this era of the industrial internet of things.

With the increased use of Android smartphones, the Android Pattern Lock graphical password has become commonplace. The Android Pattern Lock is advantageous in that it is easier to remember and is more complex than a five digit numeric code. However, it is susceptible to a number of attacks, both direct and indirect. This fact shows that the Android Pattern Lock by itself is not enough to protect personal devices. Other means of protection are needed as well.

In this thesis I have investigated five methods for the analysis of biometric data as an unnoticable second verification step of the Android Pattern Lock. The methods investigated are the euclidean barycentric anomaly detector, the dynamic time warping barycentric anomaly detector, a one-class support vector machine, the local outlier factor anomaly detector and a normal distribution based anomaly detector. The models were trained using an online training strategy to enable adaptation to changes in the user input behaviour. The model hyperparameters were fitted using a data set with 85 users. The models are then tested with other data sets to illustrate how different phone models and patterns affect the results.       

The euclidean barycentric anomaly detector and dynamic time warping (DTW) barycentric anomaly detector have a sub 10 \% equal error rate in both mean and median, while the other three methods have an equal error rate between 15 \% and 20 \% in mean and median. The higher performance of the euclidean and DTW barycentric anomaly detector is likely because they account for the time series nature of the data, while the other methods do not. Each user in the data set have provided each pattern at most 50 times, meaning that the long-term effects of user adaptation could not be studied.