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A Methodology for Formal Requirements Validation and Automatic Test Generation and Application to Aerospace Systems

United Technologies Research Center-Orlando Ferrante, Simone Rollini, Luca Manica, Valerio Senni
UTC Aerospace Systems-Eelco Scholte, Rob North
Published 2018-10-30 by SAE International in United States
Automation on Validation and Verification (V&V) leveraging Formal Methods, and in particular Model Checking, is seeing an increasing use in the Aerospace domain. In recent years, Formal Methods have been used to verify systems and software and its correctness as a way to augment traditional methods relying on simulation and testing. Recent updates to the relevant Aerospace regulations (e.g. DO178C, DO331 and DO333) now have explicit provisions for utilization of models and formal methods. In a previous paper a compositional methodology for the verification of Aerospace Systems has been described with application to Electrical Power Generation and Distribution Systems. In this paper we present an expansion of the previous work in two directions. First, we describe the application of the methodology to the validation of Proximity Sensing Systems (PSS) requirements showing the effectiveness of the method to a new aerospace domain. Second, both the methodology and technology components have been expanded and applied to the PSS to enable automatic generation of test cases from the validated requirements models showing a novel application of formal models…
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Multi-Layer Framework for Synthesis and Evaluation of Heterogeneous System-of-Systems Composed of Manned and Unmanned Vehicles

United Technologies Research Center-Jeffrey R. Peters, Ebad Jahangir, Amit Surana, Zohaib Mian
Published 2018-10-30 by SAE International in United States
The advancement of both sensory and unmanned technology, combined with increased utilization of autonomous platforms in complex teaming scenarios, has created a need for practical design space exploration tools to aid in the synthesis of effective System-of-Systems (SoS). The presented work describes a modular, flexible, and extensible framework, referred to herein as the Technologies and Teaming Evaluation (TATE) framework, for straightforward identification of high-quality SoS, which may include both manned and autonomous elements, through quantitative evaluation of system-level and SoS-level attributes against a set of user-defined reference tasks. More specifically, TATE combines a top-down (goal-driven) approach, which systematically decomposes mission-level goals into a set of relevant technology and teaming options, with a two-layer bottom-up (technology-driven) approach that compares and selects effective components and configurations both for individual systems and the overall team. The TATE framework serves as an extension to existing design space exploration tools that focus on individual system design and do not readily scale to SoS. A canonical example is used to illustrate the use of the TATE framework for synthesis and evaluation…
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Novel Framework Approach for Model-Based Process Integration from Requirements to Verification Demonstrated on a Complex, Cyber-Physical Aircraft System

United Technologies Research Center-Hajer Saada, Luis Diogo Couto, Fabio Cremona, Gilberto Burgio
ESI ITI GmbH-Marcel Gottschall, Bastian Binder
Published 2018-10-30 by SAE International in United States
This paper presents a demonstrator developed in the European CleanSky2 project MISSION (Modelling and Simulation Tools for Systems Integration on Aircraft). Its scope is the development towards a seamless integrated, interconnected toolchain enabling more efficient processes with less rework time in todays, highly collaborative aerospace domain design applications.The demonstration described here, consists of an open, modular and multitool platform implementation, using specific techniques to achieve fully traceable (early stage) requirements verification by virtual testing. The most promising approach is a model based integration along the whole process from requirements definition to the verified, integrated (and certified) system. Extending previous publications in this series, the paper introduces the motivation and briefly describes the technical background and a potential implementation of a workflow suitable for that target. Applying novel methodologies like agility to the aerospace domain workflow requires a sophisticated way of managing the multidimensional integration of various engineering tools and processes usually used along the development cycle. The demonstrator relies on two open standards for connecting databases of the necessary information (models) with each other and…
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Framework for Modelling and Simulation of Multi-Physics Aircraft Systems with Distributed Electronic Controllers

United Technologies Research Center-Gilberto Burgio, Leonardo Mangeruca, Alberto Ferrari, Marco Carloni, Virgilio Valdivia-Guerrero, Laura Albiol-Tendillo, Parithi Govindaraju
ESI ITI GmbH-Marcel Gottschall, Olaf Oelsner
Published 2017-09-19 by SAE International in United States
Multi-physics interactions between structural, electrical, thermal, or hydraulic components and the high level of system integration, characteristic of new aircraft designs, is increasing the complexity of both design and verification processes. Therefore the availability of tools, supporting integrated modelling, simulation, optimization and testing across all stages of aircraft design remains a critical challenge.This paper presents some results of the project MISSION (Modelling and Simulation Tools for Systems Integration on Aircraft). It is a collaborative task being developed under the European Union Clean Sky 2 Program, which is a public-private partnership bringing together aeronautics industrial leaders and public research organizations based in Europe. The first levels of integration of different models and tools proposed in the MISSION framework will be presented, along with simulation results. The paper will highlight the workflow to perform the various stages of virtual testing and the proposed way to exchange artifacts within the modelling and analysis framework. The considered system under test is an electromechanical flight control actuator together with the related control logic. The plant system is natively a physical…
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Method for Analytical Calculation of Harmonic Content of Auto-Transformer Rectifier Units

United Technologies Research Center-Virgilio Valdivia-Guerrero, Daniel Diaz Lopez
RWTH Aachen University-Rolf Loewenherz
Published 2016-09-20 by SAE International in United States
Auto transformer rectifier units (ATRUs) are commonly used in aircraft applications such as electric actuation for harmonic mitigation due to their high reliability and relative low cost. However, those components and the magnetic filter components associated to it are the major contributors to the overall size and weight of the system. Optimization of the magnetic components is essential in order to minimize weight and size, which are major market drivers in aerospace industry today. This requires knowledge of the harmonic content of the current. This can be obtained by simulation, but the process is slow. In order to enable fast and efficient design space exploration of optimal solutions, an algebraic calculation process is proposed in this paper for multi-pulse ATRUs (e.g. 12-pulse and 18-pulse rectifiers), starting from existing solution proposed for 6 pulse rectifier in the literature. The method consists of mapping AC and DC sides of a balanced 6N-Pulse system into the sum of equivalent 6-Pulse systems. This problem can then be solved with available methods, and then the AC and DC currents are…
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Design Analysis of High Power Density Additively Manufactured Induction Motor

United Technologies Research Center-Beata I. Wawrzyniak, Jagadeesh Tangudu
Published 2016-09-20 by SAE International in United States
Induction machines (IM) are considered work horse for industrial applications due to their rugged, reliable and inexpensive nature; however, their low power density restricts their use in volume and weight limited environments such as an aerospace, traction and propulsion applications. Given recent advancements in additive manufacturing technologies, this paper presents opportunity to improve power density of induction machines by taking advantage of higher slot fill factor (SFF) (defined as ratio of bare copper area to slot area) is explored. Increase in SFF is achieved by deposition of copper in much more compact way than conventional manufacturing methods of winding in electrical machines. Thus a design tradeoff study for an induction motor with improved SFF is essential to identify and highlight the potentials of IM for high power density applications and is elaborated in this paper. A traction/propulsion motor application is considered due to its demanding requirements on power density, constant power to speed ratio and efficiency. The motor design space explores different number of poles, slots-per-pole-per-phase and slot fill factors while satisfying the stringent requirements.…
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Multi-Domain Modelling of 3 Phase Voltage Source Converters in Modelica Language

United Technologies Research Center-Francisco Gonzalez-Espin, Laura Albiol-Tendillo, Virgilio Valdivia-Guerrero, Ray Foley
RWTH Aachen University-Rolf Loewenherz
Published 2016-09-20 by SAE International in United States
This paper will present a multi-domain (electrical and thermal) model of a three phase voltage source converter and its implementation in Modelica language. An averaged model is utilised for the electrical domain, and a power balance method is used for linking the DC and AC sides. The thermal domain focuses in deriving the converter losses by deriving the analytical equations of the space vector modulation to derive a function for the duty cycle of each converter leg. With this, the conduction and switching losses are calculated for the individual switches and diodes, without having to model their actual switching behaviour. The model is very fast to simulate, as no switching events are needed, and allows obtaining the simulation of the electrical and thermal behaviour in the same simulation package..
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Energy Storage for Commercial Hybrid Electric Aircraft

United Technologies Research Center-Jonathan M. Rheaume, Charles Lents
Published 2016-09-20 by SAE International in United States
Energy storage options for a hybrid electric commercial single aisle aircraft were investigated. The propulsion system features twin Geared Turbofan™ engines in which each low speed spool is assisted by a 2,500 HP electric motor during takeoff and climb. During cruise, the aircraft is powered solely by the turbine engines which are sized for efficient operation during this mission phase. A survey of state of the art energy storage options was conducted. Battery, super-capacitor, and flywheel metrics were collected from the literature including Specific Energy (Wh/kg), Volumetric Energy Density (Wh/L), Specific Power (W/kg), Cost ($/kWh), and Number of Cycles. Energy storage in fuels was also considered along with various converters sized to produce a targeted quantity of electric power. The fuel and converters include fuel cells (both proton exchange membrane and solid oxide operating on hydrogen or on jet fuel) and a turbogenerator (jet fuel or LNG). The various energy storage options were compared across a range of stored energy on the basis of weight. The selection of a lightweight energy storage technology depends on…
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Topology Optimized End Winding for Additively Manufactured Induction Motor with Distributed Winding

United Technologies Research Center-Vijay Jagdale, Jagadeesh Tangudu
Published 2016-09-20 by SAE International in United States
It is desired to reduce stator end winding length and mass to reduce associated resistive losses, increase efficiency and power density of an induction motor. With recent advancements in additive manufacturing technology, it is possible to deposit copper conductive paths and insulation layers in a selective controlled manner. This enables more compact end winding designs. The objective of this paper is to present a topology optimization based approach for design of stator end winding to minimize its overall length, volume and mass. Design approach and parametric study results for a representative stator design are presented in this paper. By reducing length of end winding, efficiency and power density of the induction motor can be increased enabling benefit realization for weight critical aerospace applications, incorporation in electric vehicle market and potentially reducing rare-earth dependency.
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Design and Testing of a High Temperature Inverter

United Technologies Research Center-Shashank Krishnamurthy, Stephen Savulak
D.Y. Innovations-Yang Wang
Published 2016-09-20 by SAE International in United States
The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. The wide band gap devices in conjunction with silicon on insulator electronic components enable the realization of power converters that can operate at high ambient temperatures that are typically found in aerospace engine environments. This paper describes the design and test of a power electronic inverter that converts a fixed input DC voltage to a variable voltage variable frequency three phase output. The design of the key functional components such as the gate drive, power module, controller and communication will be discussed in this paper. Test results for the inverter at high temperature are also presented.
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