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Meeting	ACGS Committee Meeting 92 - Dayton - October 2003
Agenda Location	6 SUBCOMMITTEE C – AVIONICS AND SYSTEM INTEGRATION 6.3 FHS and ARTIS – DLR Rotorcraft Demonstrator for Manned and Unmanned Flight
Title	FHS and ARTIS – DLR Rotorcraft Demonstrator for Manned and Unmanned Flight
Presenter	Frank Thielecke
Affiliation	German Aerospace Center, Institute of Flight System
Available Downloads*	none
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Abstract	FHS – Flying Helicopter Simulator In November 2002 the German Aerospace Center (DLR) received its new in-flight simulator, the Flying Helicopter Simulator (FHS). It was planned and developed in a joint effort of the DLR, Eurocopter Deutschland (ECD), and Liebherr Aerospace Lindenberg (LLI). Funding was provided by these organizations and by the German Ministry of Defence (BMVg). The development of the FHS was started in 1996. As basic aircraft, the Eurocopter EC135 was selected. However, the conversion of the original EC135 helicopter into the FHS research platform required significant modifications. The general guideline was to design a vehicle with a high application oriented flexibility, i.e. to cover a wide range of user requirements in order to support the various national and international research and technology programs. There are two major areas in the spectrum of user needs: Airborne simulation gives the possibility to modify the dynamic characteristics of the basic helicopter in the way, that the pilot has the impression to fly a different vehicle. Such modifications range from the variation of a single parameter, like increase of a time delay between pilot input and actuator response - used to demonstrate PIO tendencies - up to the simulation of a different helicopter that may not even exist in reality but can still be in a design phase. In comparison to ground based simulators, the pilot is in a true airborne environment with real sight and motion cues. The airborne simulation is not only an excellent tool for basic and applied research in handling qualities, controls, displays and human factors. It will assist in the design and development of new helicopters and it allows detailed evaluation of their future characteristics before the actual vehicles exist. This avoids later expensive modifications in the development process of a real helicopter. For fast changes required in the research environment, a high degree of flexibility must be provided for the airborne simulation role. The second key area for the FHS is the development, integration and qualification of new technologies, like active control components, new flight control laws, and new cockpit systems. These applications also need a high flexibility in system changes to implement both hardware and software modifications. Technology demonstration encompasses evaluating and proving the functionality and operational benefit of new technologies up to the point of certification. To meet the future requirements a completely new control system and system architecture were developed. The original mechanical control system was removed and replaced by a full authority digital fly-by-light system. Major emphasis in the design was placed on two essential factors: high safety standard, according to the stringent civil certification requirements and at the same time, maximum flexibility for configuration changes due to user needs. The FHS had its first flight with the fly-by-light control system in January 2002. After extensive ground and flight testing under the responsibility of ECD the helicopter was delivered to the DLR in November 2002. It is operated by the DLR research center in Braunschweig, where also ground support elements are located, which complete the FHS system: a ground based system simulator and two ground facilities, a telemetry station and a data evaluation station. As these stations are installed in two transportable containers the FHS can be used in other locations without major external support. This first part of the presentation will at first concentrate on the FHS helicopter itself. Emphasis is placed on the design philosophy, safety considerations, and handling of the control system by the pilots. Then the main features of the ground simulator and the ground stations are addressed. Finally, an overview of the present use of the FHS is given and the potential for future user programs is outlined. ARTIS – Autonomous Rotorcraft Testbed for Intelligent Systems The DLR-Institute of Flight Systems is developing a technology demonstrator for autonomous VTOL flight. The Autonomous Rotorcraft Testbed for Intelligent Systems (ARTIS) is designed to be an inexpensive multi-purpose research platform. The presentation gives an overview of the rotorcraft UAV design, as well as introduces the research agenda for the ARTIS project and thus will provide an outlook on planned areas of UAV related research at DLR. Design requirements for the VTOL testbed are to keep operational costs to a minimum and to guarantee a maximum payload of 6kg. Encouraged by similar successful unmanned rotorcraft programs, a commercially available acrobatic helicopter with a rotor diameter of 1,80 m was selected for the ARTIS program. A multi-sensor navigation system based on commercial-of-the-shelf components is being integrated, resulting in an autonomy-enabling avionics suite with a total weight about 3kg, leaving another 3kg of payload for experiments. The first experimental payload for ARTIS will be an intelligent multi-sensor vision system for use in object recognition, collision avoidance, automatic decision making, multi-agent planning and control algorithms. Biologically inspired approaches like stereo vision and the analysis of optical flow as a measure for distance are under investigation. The imitation of the behavior of a fly which passes obstacles in a safe distance by keeping the optical flow constant seems to be a possible method to implement a generic obstacle avoidance system on an aerial vehicle. The machine vision system will also be used for a relative position hold system to hover over a moving object and to study similar vision-based methods for guidance and navigation as an alternative means to satellite based augmentation. Similar functions have been demonstrated by DLR on a man-carrying helicopter earlier3 and now have to be modernized and adapted to UAV applications. An important area of research also covered by using ARTIS is the evaluation of methods for robust and adaptive operation in uncertain environments. The required high level of autonomy will be achieved by an automated on-board decision and planning system. The evolving system will be extended to support the development and comparison of algorithms for co-operation of multiple vehicles. Co-operation and information flow in a multi-vehicle environment, which includes co-operative path planning and collision avoidance algorithms, are going to be flight tested by using multiple ARTIS helicopters. In the field of flight controls, ARTIS will be used to experiment and evaluate advanced flight control methods for unmanned helicopters in order to improve the number of possible missions for this vehicle category. In the far term, the Flying Helicopter Simulator (FHS), a modified Eurocopter EC135 with fly-by-light controls and an interface for experimental flight control systems. is planned to be used for demonstrations of autonomous functions, which are first to be developed and evaluated on the smaller scale ARTIS UAV. Initial flight tests with the small helicopter have recently been conducted. This second part of the presentation covers also the results and lessons learned of the first flight test campaign. The current project timeline aims for autonomous operation of the vehicle with waypoint navigation by the end of 2003. First research results as well as demonstrations of vision based functions, more powerful guidance and flight control algorithms are scheduled for 2004.