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The application of continuous integration and test methodologies to rotorcraft HUMS
No full textContinuous Integration and Test (CIT) is a mature technique used to support Agile software development practices and it has seen increasing adoption for avionics software development over the last 10 - 15 years. However, point solutions are usually adopted for avionics CIT as standard frameworks for implementing it do not exist. Test PASS, developed by The Warsaw Institute of Aviation (WIA) in collaboration with General Electric Company Polska (GECP) is proposed as a framework for CIT in an embedded, safety critical environment. Its application to GE’s next generation HUMS is described as a challenging use case that fully demonstrates the framework’s flexibility and capabilities. The challenges of implementing a CIT approach for HUMS are presented as are the solutions enabled by Test PASS. The benefits to the GE’s next generation HUMS product including improved robustness and development effort efficiencies are described
Optimization based inverse simulation method for helicopter pull up maneuver
No full textThe aim of this work is to perform helicopter Pull Up maneuver with inverse simulation methodology. This method is based on the combination of Broyden-Fletcher-Goldfarb-Shanno (BFGS) and line search optimization algorithms. By using the inverse simulation method, unsteady maneuvers can be performed automatically by changing the control inputs of the helicopter. In addition, maneuverability, agility and performance limits can also be determined. In the conventional methods, trial-error is being performed in order to achieve the maneuver. However, inverse simulation method not only saves time due to trial-error but also increases the accuracy of the aimed maneuver. In the inverse simulation numerical optimization problem, pilot control inputs are defined as the design variables. By changing the pilot inputs, objective function which defines the target maneuver is minimized. The algorithm is used to perform a Pull Up maneuver at maximum achievable load factor for a large category rotorcraft within the available engine power and rotor control limits. Flightlab® software is used for the flight simulations. In mathematical model, blades are modelled as rigid and flow is modelled as uniform inflow. Nonlinear transient Pull Up simulation have been performed and maximum 3.5g is obtained
Flight evaluation of advanced Sbas point-in-space helicopter procedures facilitating Ifr access in difficult terrain and dense airspaces
No full textThis paper describes the work performed within the framework of the SESAR2020 project “Enhanced Arrival and Departures” (PJ.01 EAD). The Solution PJ.01-06 within Project PJ01 assessed and validated the benefit of advanced Point in Space (PinS) rotorcraft flight procedures. Advanced PinS, which use curved segments and straight segments in the construction of IFR routes, are key enablers for the simultaneous non-interfering concept, noise abatement approaches, and helicopter access in difficult terrain. Three exercises were conducted to demonstrate and analyze the benefits two different enabling technologies. Exercises one and two integrated a synthetic vision system (SVS), a flight management system (FMS) together with a Helmet-Mounted Display (HMD) supporting manual flight that can increase the safety and reliability of rotorcraft operations through dedicated symbology for specific rotorcraft operations, especially during arrival and departure operations including visual segments. The third exercise used an IFR-certified avionics suite (Helionix®), including a flight management system (FMS) and a 4 axis autopilot to automatically fly an advanced PinS approach with different descent profiles. This paper describes the entire validation process, starting with the design of the PinS procedures for Braunschweig and Donauwörth heliport, the hardware integration of both the helmet-mounted display system and flight management system into DLR’s Generic Cockpit Simulator (GECO) and research helicopter ACT/FHS (Active Control Technology / Flying Helicopter Simulator), as well as the implementation of real-time simulation and flight tests at Braunschweig and Donauwörth. The results of these validations and a conclusion based on them are also presented
Analysis of rotorcraft pilot couplings from the flight control system modes perspective
No full textThis paper investigates Rotorcraft Pilot Coupling (RPC) with different Flight Control System (FCS) modes. A generic 16DOF nonlinear helicopter model configured with Rate Command Attitude Hold (RCAH), Attitude Command Attitude Hold (ACAH) and Translational Rate Command (TRC) mode has been developed to run simulations on triggering PIO. In addition, ROVER has been extended to multi-axis ROVER to detect PIO. The control mode sensitivity and tolerability to pilot time delay, actuator saturation, actuator rate limit, control authority of the Stability and Control Augmentation System (SCAS) and sensor dynamics are studied. Results show that: 1) the tolerance to the pilot time delay is highest for the TRC mode, followed by ACAH and RCAH; 2) inner vehicle trigger factors (actuator saturation, actuator rate limit, control authority and sensor dynamics) play a more important role than external trigger factors (pilot time delay) in triggering PIO; 3) inner vehicle trigger factors make the RCAH, ACAH and TRC mode more sensitive to pilot time delay; 4) the tolerability of different control modes to abnormal actuator saturation is the same; 5) for actuator rate limit and control authority, the TRC mode has the highest tolerance, followed by ACAH and RCAH; 6) TRC mode and RCAH mode have the same tolerability to abnormal sensor dynamics while the tolerability of ACAH is lower. These findings offer guidance for designing pilot-in-the-loop simulator experiments that will further investigate RPCs related to different control modes
Preventing dynamic rollover in brownout
Get PDFThe Institute of Flight Systems at the DLR (German Aerospace Center) site in Braunschweig, Germany is trying to find ways to improve the safety of helicopter operations. One very dangerous type of operation that is the landing of a helicopter. Loss of situational awareness can lead to unwanted contact with objects or a dynamic rollover when touching the ground. This paper presents research with optical navigation methods that has been conducted towards minimizing the danger of a dynamic rollover in bad visual conditions. Optical navigation is a method that is often used for navigating small unmanned aircraft. However, the so far conducted research in that field usually focuses on undegraded visual environment. Most of the optical navigation methods are designed to work with images that can fully be evaluated. In this paper, a set of existing optical navigation methods is tested towards the ability to work in degraded visual environment. Further, a self-developed method is presented that has been designed to be abe to work in scenarios where most parts of an image cannot be evaluated. The methods are tested on recorded flight test data. These flight test data are modified with a set of masks that simulate a visibility impairment. The conducted tests show that existing optical navigation methods do struggle when the complete image area cannot be evaluated. The evaluation of the self-developed method shows that it is not affected by impaired sight. However, its performance in situations with non-restricted sight shows to be behind the performance of some of the existing methods
Actuation requirements of an active tendon concept in rotorcraft
Get PDFThe paper introduces the actuation requirements of an active tendon concept that is being developed under the Horizon 2020 SABRE project (Shape Adaptive Blades for Rotorcraft Efficiency). The basic idea of the concept is to incorporate a tensile structural member (referred to as a tendon) into a rotorcraft blade to introduce a means of controlling the blade’s effective stiffness and hence its dynamic properties. This control mechanism should ensure that potentially harmful rotor resonances in various flight regimes are effectively and adaptively avoided. In previous studies, free vibration analysis for the blade-tendon system was conducted numerically and validated against non-rotating experiments. The resulting models are used here to support conceptual design and sizing of the tendon loading system. The actuation requirements in terms of the actuator force, stroke, power and other measures are discussed for simplified representations of the Bo105, Lynx XZ170 and EH101 helicopter rotor blades. It is shown that electro-mechanical linear actuator technology offers realizable loading approach and nominal peak loads of around 6 kN allow adaptive decrease of the in-plane and out-of-plane bending natural frequencies between 0.05/rev and 0.2/rev
Visual-vestibular motion cueing assessment in maritime rotorcraft flight simulators
Get PDFConfidence in the Modelling and Simulation (M&S) tools used in flight simulators depends upon the identification of the fidelity requirements for a particular application. The critical M&S elements integrated into the helicopter-ship dynamic interface simulation environment are motion and visual cueing, the flight dynamics model, unsteady ship’s airwake and deck motion. The paper reports the results of a piloted flight simulation experiment conducted in a full-motion simulator, to study the effects of varying the visual and vestibular motion cueing fidelity on the pilot’s perception, task performance and workload. Three different motion tuning sets were tested in three visual cueing scenarios for a representative SH-60B ‘Seahawk’ helicopter landing on a naval single-spot destroyer at different wind and sea-state conditions. It was found that when high-fidelity vestibular motion was provided to the pilot, the dependency on the visuals to capture aircraft state information was reduced. Similarly, when the high-fidelity visual cueing was provided, the pilot perceived balanced and synchronised overall motion cues leading to reduced workload and improved task performance. Moreover, the individual and combined effect of visual-vestibular fidelity was found to be more noticeable at higher wind and sea conditions, for which an ‘Optimised’ vestibular motion tuning set and a High Visual Cueing scenario combination was obtained, this led to reduced pilot workload and improved simulated maritime helicopter operational capability
Design evaluation and performance assessment of rotorcraft technology by 2050
Get PDFThe extended Clean Sky Joint Technology Initiative (JTI) within the EU Horizon 2020 Framework Programme [Ref. 1] proposes to introduce a number of concept aircraft and rotorcraft to replace reference technology counterparts at different time scales (2020/2035/2050). This Clean Sky 2 (CS2) promotes the importance of those concept configurations and their application in the future. An increasing global demand within and outside the European Union (EU) for an efficient air mobility and transportation system (i.e. more flexible, resilient, effective and affordable), and future projected growth for its application, will lead to the requirement for development of highly optimised transportation solutions. Within CS2, the project DEPART2050 (Design Evaluation and Performance Assessment of Rotorcraft Technology by 2050) aims to undertake the environmental and socio-economic assessments for two fast rotorcraft technologies, being the tilt rotor aircraft and the compound rotorcraft under development by the Original Equipment Manufacturers (OEMs), the NGCTR and the Racer. Such fast rotorcraft with improved capabilities (higher payload, range and speed) will have an inherent advantage. This will enable the utilisation of smaller airports (as they can operate from shorter runways) and optimally located heliports. The objectives of the project work will be to undertake at airport level and at Air Transport System (ATS) level, assessments of environmental (emissions and noise) and mobility (connectivity and productivity) improvements that may be accrued through replacement of reference helicopter technology over the designated time scales. The assessments will be made for a selected number of mission scenarios: Search and Rescue, Oil and Gas, Emergency Medical Service, Passenger Air Transport and Cargo Transport. To widen the scope of the DEPART2050 project, additional assessments will be performed for two generic fast rotorcraft: a tilt rotor aircraft and a compound rotorcraft. These generic rotorcraft, having been defined by the DEPART2050 project partners, are different from and do not represent the ones under development by the OEMs within CS2 (NGCTR and Racer). Within the DEPART2050 project so far, the rotorcraft configurations have been defined and the models set up. The assessment metrics and missions have been further detailed. Initial assessments have been performed for fuel consumption, exhaust gas emissions, noise impact and mobility impact, showing that the set-up is viable and that results are in line with expectations. Considerable reductions have been found for fast rotorcraft relative to conventional helicopters, both in fuel consumption and CO2 emission per passenger-kilometre, as well as in absolute travel time. But it also has become clear that more work is required to come to actual and final conclusions. The project will run till late 2021 and more results will become available in due time
Helicopter forward-looking warning method based on image matching for urban low-altitude flight
Get PDFAiming at the unique geographical characteristics of urban environment, combined with image matching aided navigation and forward-looking warning technology, the helicopter forward-looking warning method based on image matching is studied. Based on precise navigation and positioning, dangerous obstacles are predicted and warnings are generated. Firstly, the image matching algorithm applied to helicopter forward-looking warning is studied, and a normalized cross-correlation matching algorithm based on variable step-size second-order difference fast search strategy is proposed. Then, the principle and algorithm of helicopter forward-looking warning algorithm are given, and the warning boundary is determined based on helicopter escape trajectory. A test example is built to verify the algorithm. The simulation results show that compared with the conventional warning method, the ground proximity warning algorithm based on image matching can effectively correct the navigation error and improve the success rate of the warning, especially suitable for low-altitude anti-collision warning in urban environment. The proposed fast search strategy of variable step-size second-order difference method can effectively improve the speed of the algorithm
Increasing helicopter flight safety in maritime operations with a head mounted display
Get PDFTo increase flight safety and operational availability for helicopters, the potential benefits of helmet mounted displays (HMD) are investigated, with a focus on maritime operations. Helicopters have long downtimes, due to harsh weather conditions or other visual impairments, especially in maritime scenarios. Flying in these poor conditions can drastically reduce flight safety. It is often difficult to recognize the horizon due to sea fog, and the absence of reference objects can complicate the maritime flight. These conditions and especially the downtimes cost money or, at worst, life’s. Therefore, DLR integrated the augmented reality glasses Microsoft HoloLens into DLR’s simulator AVES to use it as HMD for pilots. Subsequently, displays and symbolism were developed and evaluated. To carry out a piloted simulator study, a maritime scenario was created to measure changes in the pilots’ performance with the HMD, like workload or situational awareness. The paper focuses (a) on the integration of the HoloLens into the simulator with its challenges, solutions and findings, (b) on the symbolism and (c) on the piloted simulator study. Both the quality of the HoloLens as HMD and the study results are very positive. The pilots rated high usability, reduced workload, increased situational awareness and increased safety