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For actuation of high lift surfaces in modern airplanes, complex mechanical shaft transmission systems powered by central drive units are deployed. The design of mechanical actuation systems, which have a major share in the weight of secondary flight controls, is a complex and challenging engineering task. Especially for specification of essential component and system design parameters within the preliminary design phase, engineering skill and experience are of significant importance owing to many uncertainties in component data and boundary conditions. Extensive trade-offs, as well as an evaluation of the system requirements and constraints lead to an iterative and time-consuming design process. Utilizing an integrated design assistance tool, mathematical functions and constraints can be modeled on system and component level and formalized as a constraint satisfaction problem (CSP). Thus, automated consistency checking and pruning of the solution space can be achieved.

This paper focuses on the virtual integration and test approach used for the evaluation of an automation system developed for the multifunctional operation of fuel cells in commercial aircraft. In order to accomplish the virtual integration a model of the overall automation system is linked with a dynamic model of the complete fuel cell system. For this purpose a modeling approach for complex physical systems is described in this paper. During virtual testing various simulation runs are executed based on automatically generated test cases, which cover a complete flight mission. For this reason a flight mission is modeled as a Statechart that includes next to time- based flight phases also potential events and malfunctions (e.g. engine flame-out, cargo fire). An algorithm is described, which can find all possible state combinations including parallel event sequences.

Simulation of avionics equipment is essential due to the complex nature of its development and integration process. Throughout the development process, executable component models are used to demonstrate the feasibility and the compliance of the system design with respect to its functional requirements. In later development phases, there is the need for system integration tests where a mix of real and simulated equipment is used to verify the overall system behavior. Since Boeing 777 and Airbus A380 programs, IMA1 technology has entered several civil aircraft systems. In recent programs like Boeing 787 and Airbus A350 the number of IMA components has significantly increased. In this paper we present a simulation model for a new IMA component - the common Remote Data Concentrator (CRDC)2, which is developed by Thales-Diehl for the Airbus A350 XWB. Building simulation models of IMA components is in general a challenging task due to their complexity on both software and hardware level.

This paper presents a methodology to develop, optimize and evaluate fuel cell system architectures. The main focus is placed on the sizing and optimization process which uses the simulation tool Matlab/Simscape. A model library is introduced which contains parametric behavior models. The benefit of this is that the size of the components is not fixed by the parameters. The size of the components is driven by the energy and mass flows of each component. Thus the implicit sizing and optimization process is easy to handle and numerically robust. Illustrative results are shown for a fuel cell system.

In the paper at hand a model-based development approach for a diagnostic system for a multifunctional fuel cell system architecture will be presented. The approach consists primarily of four parts. The first part is a description of general steps needed to build an accurate component-based model of the system using a state of the art model-based diagnostic reasoning tool. As a first result there will be a static simulation model for nominal system behavior. The second part of the approach deals with the identification of safety critical failure conditions (SCFC) at a system level, e.g. low Power. The SCFCs are then mapped into the model. This means that categorized physical quantities and monitoring executives are chosen, that are appropriate for representing the specific SCFCs, e.g. low voltage at outlet of DC-DC converter module. According to step two there will be conflicts, meaning discrepancies between the simulated nominal and the mapped behavior.

Friction induced vibrations in brakes are a topic of major interest and concern for the automotive industry. The structural vibrations that may occur, as well as the audible noise that can be related to them, may lead to consequences as diverse as driver discomfort, maintenance requirements, and even safety issues. Although friction induced vibrations are known already since the beginnings of friction brake design, a generally accepted consensus on many aspects, like fundamental mechanisms or generic solution approaches, seems still to be debated. The present paper attempts to shed some light on the reasons for these persisting difficulties. A review of the different classes of phenomena appearing is given, which could be understood as an attempt to limit the scope of phenomena considered as friction induced. Research topics and disciplines involved will be identified and a clarification of achievements and unanswered questions will be attempted.

Strong market growth, upcoming global competition and the impact of customer-requirements in aerospace industry demand for more productive, flexible and cost-effective machining systems. Industrial robots have already demonstrated their advantages in smart and efficient production in a wide field of applications and industries. However, their use for machining of structural aircraft components is still obstructed by the disadvantage of low absolute accuracy and adverse reaction to process loads. This publication demonstrates and investigates different methods for performance assessment and optimization of robot-based machining systems. For conventional Cartesian CNC machining systems several methods and guidelines for performance assessment and error identification are available. Due to the attributes of a common 6-axis-robot serial kinematics these methods of decoupled and separated analysis fail, especially concerning optimization of the system.

For an “end-to-end passenger experience that is secure, seamless and efficient” the International Air Transport Association (IATA) proposes Near Field Communication (NFC) and a single token concept to be enablers for future digital travel. NFC is a wireless technology commonly utilized in Portable Electronic Devices (PEDs) and contactless smart cards. It is characterized by the following two attributes: a tangible user interface and secured short range communication. While manufacturers are currently adapting PED settings to enable NFC in the flight mode, the integration and use of this technology in aircraft cabins still remains a challenge. There are no explicit qualification guidelines for electromagnetic compatibility (EMC) testing in an aircraft environment available and there is a lack of a detailed characterization of NFC equipped PEDs.

Development for the Integrated Modular Avionics (IMA) platform is complex owing to the variety of equipment, vendors and non-uniform tools. The development should be simplified by a model-based harmonized tool environment by means of an integrated set of tools of different type, origin and purpose. Eclipse's flexible and modular architecture seems adequate as a framework for such a harmonized IMA development environment. This article evaluates how Eclipse could practically be utilized for this purpose. The IMA process and development requirements like concurrency, different process roles, and multiple tools are mapped to the Eclipse framework. In addition, open-source extensions for model-based engineering and application development are integrated in the tools chain. In order to test the performance, openness and compatibility of Eclipse and the tools from the IMA development process, six current and future tools are integrated into a prototype of a common Eclipse instance.

This paper presents a model-based design and verification approach, which is used to develop a complex state-based fuel cell control system. The architecture of the control system is organized in a hierarchical manner with one supervisory controller and several system controllers. The used development approach considers the systematic design of this hierarchical concept and enables the integration of requirements. The single modules of the control system are modeled as Statecharts. During the design process a method based on Petri Nets is used to analyze and verify the state-based structure of the supervisory controller. The verification of the control system functionalities is finally realized by a black box test approach. The required test sequences are systematically specified on the basis of the state transition graph of the supervisory controller.

The integration of fuel cell systems as an independent energy source (Auxiliary Power Unit, APU) requires enhanced aircraft cooling architectures. New environmental control systems and systems with an increased cooling demand are investigated in various research projects. Cooling system architectures can be designed which benefit from similar requirements, e.g. by using the same cooling loops. Additionally, an increased cooling demand makes the investigation of alternative heat sinks necessary. For detailed system investigations simulation studies are used. A model library has been created in Dymola/Modelica containing the necessary component models to simulate cooling systems. The used modeling approaches and main model information are presented in this article. In order to understand the basic system behavior a Design of Experiment (DOE) is useful. If only two or three parameters are considered, simulation studies can be performed for each possible parameter combination.

This paper presents a model-based approach for the multi-objective design of optimized diagnosis functions for high lift actuation systems. These systems are used to augment lift at low speed during takeoff and landing, and are safety critical. This demands requirements to the detection of failures and the isolation of root causes in order to provide a high availability at low risk. Dedicated functions cover the determination of features, the detection of symptoms and the isolation of root causes by means of inference and resolution. The aim of the design approach is to provide these functions in an optimal manner with respect to multiple objectives. In order to be clear and traceable the approach consists of separate consecutive steps. These are arranged by using systems engineering principles. With respect to requirements, models of different levels of detail are developed and used to design stepwise all required functions.

This paper describes the conceptual design of a variable-speed fixed-displacement electric motor pump for aircraft hydraulic systems. In contrast to today's approaches, the pump controls the constant system pressure by adapting the motor speed rather than the pump displacement or both. This concept might increase the pump's part load efficiency significantly. The paper starts with introducing and analyzing the dynamic requirements of aircraft hydraulic pumps and evaluating different pump concepts. The concept of an internal gear pump driven by a permanent magnet synchronous motor is selected. For this concept an experimental prototype is developed. The electric motor pump is modeled and a pressure controller is designed. The prototype is set up and tested on an experimental test bench regarding dynamics, efficiencies and noise emissions. The overall concept is evaluated regarding secondary power demand, system heat load, wear, reliability, noise, and mass.

Aircraft are high value-adding and long-living assets, while aircraft cabins are expensive consumer products tailored to each customer. Vastly changing requirements and needs force aircraft holders regularly to instruct modifications in order to remain attractive on the market. Adaptations, modifications, and development of innovations are handled by multiple organizations, not by a central one like the aircraft’s manufacturer or owner. Although the Continuing Airworthiness Management Organization manages all aircraft instance-specific documents as required by aviation regulations, their format and types of management differ. Besides, not all information that arises during a parts design phase is included. That means, overall, the consistent model-based maintenance of data within all phases of PLM up to disposal is not guaranteed.

The demand for higher production rates in aircraft industry requests more flexible manufacturing solutions. A bottleneck in production is the machining of large components by vast portal machines. Time-consuming referencing processes result in non-satisfying cost-effectiveness of these high-invest-machines. Mobile robot-based solutions are able to operate simultaneously which increases the productivity significantly. However, due to the limited workspace of robots, machining tasks have to be divided and long trajectories are separated in single overlapping segments. Thus high-accuracy referencing strategies are required to achieve desired production tolerances. In this publication different advanced optical reference strategies will be discussed taking the inhomogeneous behavior of a mobile robotic machining system into account.

Due to their unique and favorable properties as well as high strength to weight ratio, composite materials are finding increasing applications in automotive, aircraft and other vehicle manufacturing industries. High demand, production rates and increasing part complexity, together with design variations require fast, flexible and fully automated assembly techniques. In automotive and aircraft manufacturing, widely used bonding and sealing processes are automated using industrial robots due to their speed, flexibility and large working volume. However, there are limitations in achieving complete automation of these processes due to the inherent inaccuracies of the industrial robots, workpiece positioning and process tolerances. Currently, the robot programs are generated in CAD/CAM environment and are adjusted manually according to the actual workpiece.

Due to a shift of the major aviation concerns to focus on enhancements of the successful programs instead of pushing their successors, the need for new methodologies for aircraft system architecture design emerges. Challenging the existing requirements and reconsidering the functions and their allocation could help to dissolve the system specific development paradigm and lead to beneficial architecture concepts. To help understand the mechanisms and boundary conditions of developing fault-tolerant systems, the first part of the paper gives an overview of the successive process of architecture design. The significant architectural design decisions and the concurrent safety assessment process are discussed. One crucial step in the design space exploration of future aircraft system architectures is the allocation of the consumers to the available power sources. Within the paper a methodology for the optimization of the power allocation for flight control systems is proposed.

The paradigm shift to focus on an enhancement of existing aircraft systems raises the question which of the many possible incremental improvements results in an advantageous solution still considering all existing requirements. Hence, new methodologies for aircraft system design are a prerequisite to cope with such huge and complex design spaces. In the case of flight control system optimization, major design variables are the control surface configuration and actuation as well as their functional allocation. Possible architecture topologies have to be verified inter alia with respect to system safety requirements. In this context, flight dynamic characteristics and handling qualities of the fully operational as well as of several degraded system states of each topology have to be evaluated and checked against common specifications. A model-based verification of the requirements is favorable, resulting in a rapid reduction of the design space.

The continuous need for improved high lift performance motivates the evaluation of innovative high lift systems. Single flap drive systems are possible solutions to implement novel functionalities for aerodynamic performance optimization. The previously mechanical coupling needs to be replaced by approved equivalent means. This directly results in high demands on control and monitoring of the multiple single drive systems in order to preserve a safe operation. In the context of the national German research project SysTAvio, strategies for a new concept of a multifunctional high lift system are investigated and presented in this paper. The conceptual system comprises four single flap surfaces, each driven by a local transmission system and powered by a local power control unit. This architecture requires an innovative control strategy for a safe operation of a single drive system as well as synchronous movement of multiple systems.

For the shift to more-electric aircraft systems, the system specific design paradigm has to be dissolved and the allocation of functions has to be reconsidered. Including more degrees of freedom within the architecture design process for aircraft systems could lead to beneficial architecture concepts. However, new methods for conceptual systems design are required, to cope with the significantly increasing number of potential architecture variations to be evaluated. Within this paper, the GENESYS methodology enabling the design and evaluation of numerous architecture variations will proposed. The methodology consists of several modules, each dedicated to a specific process step of conceptual aircraft system design. Initially, a method for the design-independent analysis of the aircraft level functions and the identification of requirements for the aircraft systems will be illustrated.