Umut Durak

Situation aware UAV mission route planning

This paper outlines an agent based approach for UAV (Unmanned Air Vehicles) mission route planning problem. In this context, mission route planning can be defined as finding the “best” set of waypoints for the UAV that will enhance its probability of success in its mission. Mission route planning may be carried out either in premission or in mission time. It may be done either by an onboard control system or by a ground mission planning system. Regardless of these considerations, a problem solving agent for UAV mission route planning problem is proposed in this research. Mission Route Planning Agent in UAV mission route planning context needs to perceive the elements in its environment and comprehend the meaning of this situation to compute a route. In other words, it will use target, threat, terrain and air space restrictions to compute the “best” route for that UAV mission. In a dynamic replanning environment, it will compute its new route again and again each time the situation has changed. To compute the “best” route, an A* based graph search algorithm is used. For a node, while real cost is computed using fuel and threat costs with determined weightings, heuristic cost is selected as the geometric distance. Network is constructed in the search time. Consecutive nodes are determined by spanning range and azimuth with determined increments. The values of weightings for fuel and threat costs and the increments used to construct the network have a great effect on the resulting route and the computation time. While common practice is to use default or user defined values for those, this paper presents a situation aware UAV Mission Route Planning Agent that uses the tactical situation to determine these values.

An ontology for trajectory simulation

From the concept exploration for a weapon system to training simulators, from hardware-in-the-loop simulators to mission planning tools, trajectory simulations are used throughout the life cycle of a weapon system. A trajectory simulation can be defined as a computational tool to calculate the flight path and flight parameters of munitions. There is a wide span of trajectory simulations differing widely with respect to their performance and fidelity characteristics, from simple point-mass simulations to six-seven degrees of freedom hardware-in-the-loop missile simulations. From our observations, it is a common practice in the industry that developments of these simulations are carried out as isolated projects although they rely on the same body of knowledge. We envision an ontology that will capture the common knowledge in trajectory simulation domain and make domain knowledge available for reuse. Trajectory simulation ontology, dubbed TSONT, is being developed to realize this vision

Formal Scenario Definition Language for Aviation: Aircraft Landing Case Study

Although the importance of scenarios in modeling and simulation has long been well known, there still exists a lack of common understanding and standardized practices in simulation scenario development. This paper proposes a Domain-Specific Language (DLS) to provide a standard scenario specification that will lead to a common mechanism for verifying and executing aviation scenarios, effective sharing of scenarios among various simulation environments, improve the consistency among different simulators and simulations, and even enable the reuse of scenario specifications. Following DSL design practices, the proposed Aviation Scenario Definition Language (ASDL) will provide a well-structured definition language to formally specify complete aircraft landing scenarios. In order to capture the necessary constructs for a simulation scenario, Simulation Interoperability Standards Organization (SISO) Base Object Model (BOM) is adopted as the baseline metamodel. This baseline is extended using the fundamentals of aircraft landing that cover all the domain-related concepts and terminology as constructs. By taking a formal approach in defining aviation scenarios, ASDL aims at providing consistency and completeness checking, and model-to-text transformations capabilities for various targets in the aviation scenario definition domain. The results of this work will be used to develop a graphical modeling environment and automatic means to transform scenario models into executable scenario scripts. The work presented here is the first stepping stone in formal scenario definition in aviation domain.

ONTOLOGY-BASED DOMAIN ENGINEERING FOR TRAJECTORY SIMULATION REUSE

We apply an ontology based knowledge and software reuse methodology adhering to domain engineering principles. Our domain is trajectory simulation. A trajectory simulation is a piece of software to...

Graphical Specification of Flight Scenarios with Aviation Scenario Defintion Language (ASDL)

The Aviation Scenario Definition Language (ASDL) has been proposed as a domain-specific language providing a well-structured definition language to specify departure, enroute, re-route, and landing scenarios. Exploiting the capabilities of Eclipse Modeling Framework (EMF), ASDL provides a holistic conceptual metamodel construct to define all entities, attributes, and relationships needed to specify a complete flight scenario. Representing scenario models graphically, increases effectiveness of communication by providing fast, easy, and accurate method of transferring information among interested parties. It is well known that graphical diagrams are more effective than text in the communication between end-users and or domain experts. As such, models are majorly delivered graphically and supported by graphical design and editing tools. In order to provide an easy-to-use drag and drop framework to construct flight scenario models, here we present a graphical modeling and editing interface to ASDL. The proposed graphical scenario specification tool is developed using EMF Forms within EMF which provides a rapid mechanism to develop tools for modelling languages. The effort presented here will provide a graphical modeling and editing tool to specify ASDL flight scenarios while automatically validating user input and providing consistency and completeness checking. Backed by model-driven approach, the graphical modeling interface will hide all the ASDL language development details, making the tool suitable for non-developers such as pilots and air traffic controllers. This paper will include details on building the graphical framework with Eclipse Modeling Framework. We provide the detailed components of the generated GUI, highlighting the tool’s capabilities and user’s interactions. As a case-study, we also provide an example flight scenario model built using the presented tool.

Model integration workflow for keeping models up to date in a research simulator

Flight simulators can be categorised as research simulators, engineering simulators and training simulators. Research simulators can be introduced as both test beds for flight simulator research and computational tools for flight systems and human factors research. While engineering simulators are utilised for systems development, training simulators are used for flight training. The models that are used in training simulators and also in engineering simulators are more mature and stable. On the other hand, the models in research simulators are subject to a constant change. While Model Based Design and Software Development has brought us agile model development workflows, so that modellers can update their models more easily, it came up with some serious systems integration and testing problems, so systems developers need to establish mechanisms to tackle frequent behaviour and interface changes. DLRs Institute of Flight Systems (FT) has a long tradition in flight research and simulation of various flight vehicles. Currently a modern research simulator facility is being operated at DLR Braunschweig - AVES (Air Vehicle Simulator). AVES is designed such that interchangeable cockpits of rotorcraft (EC135) and airplanes (A320) can be operated on motion and fixed-base platforms according to the particular needs. 2Simulate is the enabling real-time simulation infrastructure of the AVES. This paper presents 2Simulate model integration workflow based on Mathworks Simulink Coder.

Ontology-Based Trajectory Simulation Framework

Trajectory simulations are tools to compute the flight path and flight parameters of munitions. We present an ontology-based object-oriented reuse infrastructure and discuss the underlying model driven development methodology. The strategic objective is to make domain knowledge and software reusable across a wide variety of trajectory simulation projects.

Using System Entity Structures to Model the Elements of a Scenario in a Research Flight Simulator

While any simulation study starts with a scenario, scenario development is usually conducted in an unstructured and ad hoc manner. In order to streamline scenario development, a formal approach is envisioned in the research flight simulator facility of German Aerospace Center (DLR), namely Air Vehicle Simulator (AVES). System Entity Structure (SES) which is a high level ontology that was introduced to specify a set of system structures and parameter settings is proposed as the foundations. The paper outlines a model-based methodology for scenario development. SES is exploited for metamodeling in order to capture all possible elements of a scenario that can be simulated in AVES. Then a scenario modeling methodology is built upon this metamodel.

Model-based testing methodology using system entity structures for MATLAB/Simulink models

The increasing complexity of systems entails an increasing complexity of simulation models. Likewise, heterogeneity in system components corresponds to heterogeneous simulation models. Cyber physical systems (CPS) represent an emerging class of technical systems characterized by their complexity and heterogeneity. Developing simulation models for CPS brings various challenges, one of which is determining the simulation fidelity. Fidelity evaluation can be introduced as the degree to which a simulation model matches the characteristics of the system it represents. Due to the growth of system complexity in CPS, the number of test cases required to reach admissible coverage to assure adequate simulation fidelity is very high. Along with that, heterogeneity in system components comes on top as another challenge. Therefore, adaptability, flexibility and automation can be identified as the key characteristics of a fidelity evaluation approach that determines its success. Model-based testing (MBT) advocates the use of models for the specification of test cases and proposes workflows for automatic test case generation. This paper presents an MBT approach for objective fidelity evaluation of complex, modular simulation models. The methodology implies that appropriate data for fidelity evaluation are available. Each test model is represented according to the formal structure of experimental frame (EF). For generating an executable EF for a model under test (MUT), configurable basic models are provided by a model base (MB). In the same manner, configurable basic models for composing various MUTs are stored in the MB. The system entity structure (SES) ontology is used for the specification of a family of MUT and test model designs on an abstract level. This means that the SES describes a set of various MUT and test model structures and parameter settings. Using the SES and MB, a specific executable model consisting of an MUT and a test model can be generated. Based on these ideas an infrastructure implementation for automated fidelity evaluation of complex, modular simulation models within MATLAB/Simulink is proposed in this paper.

Scenario development: A Model-Driven Engineering perspective

Scenario development starts with capturing scenarios from the users and leads to the design and the development of the simulation environment to execute these scenarios. This paper proposes a scenario development process adopting a Model-Driven Engineering (MDE) perspective. It takes scenario development and the use of scenarios in simulation environment development put forth in IEEE Recommended Practice for Distributed Simulation Engineering and Execution Process (DSEEP) as a starting point. It then constructs a basic vocabulary including the definitions of operational, conceptual, and executable scenarios. Following MDE principles, scenario development is viewed as a series of model transformations. Operational scenarios, mostly defined in a natural language, are first transformed into conceptual scenarios, which conform to a formal metamodel. Then conceptual scenarios can be transformed into executable scenarios specified using a specific scenario definition language. Furthermore, it is also possible to generate the constructs of simulation environment design and development using model transformations. In this regard, a conceptual scenario metamodel is proposed adopting the Base Object Model metamodel as an example. Then this metamodel is used to present the proposed process with a sample operational scenario and conceptual scenario excerpts. Samples are shown how model transformation can be employed for developing a Federation Object Model and an executable scenario file.