Helicopter Simulator Research Articles

FAA AC120-63 Level C급 KA-32T 비행 시뮬레이션 모델 개발

Flight simulation model for helicopter simulator is one of the most important models which affect flight performance and handling quality. It is typical to develop the model based on the raw data and models from the helicopter designers/manufacturers. The approaches in this study were to develop the basic model based on the available resources regarding helicopter operation/maintenance and to tune and validate it based on the flight test results. The basic model was developed with maintenance manuals, flight manuals, analyses, measurements, papers and so on considering that KA-32T data could not be obtained from the manufacturer. The flight test for KA-32T was performed and the reference data for the simulation validation tests were acquired. The flight simulation model was validated to have the fidelity compatible with level C of FAA AC120-63 after comparison and tuning with flight test results.

산불에 의한 열적상승유동 해석에 관한 연구

A study is made of thermal plume flow model for the development of helicopter simulator over the forest fire. For the numerical analysis, a line fire model with Boussinesq fluid approximation, which is idealized by the spreading shape of forest fire on the ground, is adopted. Comparing full 2-D and 3-D numerical solutions with 2-D similarity solution, it has been built a new model that is useful for temperature prediction along the symmetric vertical axis of fire model for both cases of laminar and turbulent flow.

Presagis to support development of Boeing next-generation helicopter simulator

Presagis to support development of Boeing next-generation helicopter simulator

Acute Lower Limb Ischemia Associated with Use of an Immersion Suit

External compression is a rare cause of acute lower limb ischemia. Workers required to wear immersion suits during helicopter simulation training are exposed to external compressive forces which can alter the hemodynamics in arterial bypass conduits. Herein a case of arterial thromboembolization to the lower limb following the wearing of an immersion suit, in a patient who had undergone arterial bypass surgery 13 yr previously is presented. The potential for this episode of acute leg ischemia being a direct result of the compressive forces exerted by the immersion suit and the possible implications for wearers of immersion suits following arterial graft surgery is discussed.

Prediction of the Necessary Degrees of Freedom for Helicotper Real-Time Simulation Models

DOI: 10.2514/1.34278 Thepurpose of this paperis toexamine the mathematical modelingof the helicopter flight dynamics for simulator qualification and to reveal new insights into the mathematical model’s response fidelity. The paper will focus on the qualification process of the simulator mathematical model as given by joint aviation requirement STD-1H, the European standard for helicopter simulator qualification. Using the joint-aviation-requirement tolerances, defined as acceptable differences between the model results, the flight test data, and the critical-pole-distance method developed at Delft University of Technology for predicting the necessary degrees of freedom of a simulation model, the paper will perform a sensitivity study on the pitch tolerances specified by the joint-aviation-requirement regulation, investigating how these tolerances might affect the model level of detail. It will be demonstrated that depending on the rotor system, the tolerances may or may not affect the helicopter flight dynamics behavior. For an articulated centrally hinged rotor, it will beshown that the tolerances havevery little effect on the level of detail used in the modeling; for a hingeless rotor, variations in the model from an uncoupled flap-body dynamics to a coupled flap-body result in large variation in the simulation results and handling-qualities characteristics.

CO-DESIGN OF A SAFE NETWORK CONTROL QUADROTOR

This paper deals with the co-design of a Network Control System (NCS) and its diagnosis. Residuals are shown to be affected by network packet losses. A new indicator, sensitive to packet losses is proposed and thus changes in the residuals due to faults or to packet losses can be differentiated. Results are exemplified through the simulation of a 4-rotor helicopter using the Matlab/Simulink standard. The network is simulated thanks to the TrueTime toolbox.

신경회로망을 이용한 무인헬리콥터의 적응출력피드백제어

Adaptive output feedback control technique using Neural Networks(NN) is proposed for uncertain nonlinear Multi-Input Multi-Output(MIMO) systems. Modified Dynamic Inversion Model(MDIM) is introduced to decouple uncertain nonlinearities from inversion-based control input. MDIM consists of approximated dynamic inversion model and inversion model error. One NN is applied to compensate the MDIM of the system. The output of the NN augments the tracking controller which is based upon a filtered error approximation with online weight adaptation laws which are derived from Lyapunov`s direct method to guarantee tracking performance and ultimate boundedness. Several numerical results are illustrated in the simulation of Van der Pol system and unmanned helicopter with model uncertainties.

헬리콥터 비행성 평가를 위한 모의비행시험 환경의 구현

For an access to specified helicopter simulator qualification`s level C or FTD(Flight Training Device) level 5 of FAA(Federal Aviation Administration) AC(Advisory Circular) 120-63, the mathematical model of a single rotor helicopter flight dynamics is investigated. From the rotorcraft simulation model validated by evaluation of its flight performance, the feasibility of the flight dynamic model that is selected for its effectiveness has been proved. Thereby the simulation environment for evaluation of helicopter flying quality is established with the development of FTD for training and testing the flight performance

요소 기반의 헬리콥터 시뮬레이션 프로그램 개발

Typical helicopter simulation programs rely on differential equations of a closed form. However, since these equations are derived using various assumptions, their usefulness is limited to small flight regions and specific model types. This paper presents a component based rotorcraft simulation program. The program adopts methods of multi-body dynamics and is written in an object-oriented programming language. The program was validated using an AH-1G helicopter simulation. The trim results are well matched with flight test data. It is also shown that program is capable of running in real-time on a desktop computer.

헬리콥터 시뮬레이터용 6자유도 전기식 운동구현장치의 개발

민간항공안전국 등급 2를 만족하는 헬리콥터 시뮬레이터에 사용되는 6자유도 운동구현장치 개발에 관해 기술하였다. 운동판과 제어 구동장치의 기구학적 및 구조적 해석을 통해 설계 제작된 운동구현장치의 시험 평가로부터 규정에 만족하는 결과를 보였고 이로부터 실제 헬리콥터 시뮬레이터로의 적용 타당성을 확보하였다. 또한 동품의 개발 결과로 인해 그간 유압 구동체계를 사용한 운동구현장치의 단점을 전기식 구동장치 적용을 통해 새롭게 개선함과 동시에 국내 최초로 10 톤급의 적재하중 능력을 보유한 6자유도 운동구현장치를 보급하게 되는 계기를 마련하였다. In this paper, the 6-dof electric motion platform system designed for the helicopter simulator satisfying the class of the CASA(Civil Aviation Safety Authority) level 2 is presented. From the kinematic, dynamic and structural analyses for motion base and electrical actuator systems, we show the feasibility of the developed motion platform system by producing the acceptable results of the test and evaluation according to the requirements specified in the CASA level 2. Furthermore through this development we suggest newly the adaptability of the electrical actuator system up to 10 ton class motion platform system, whose usage will be broaden rapidly, substituting with the advantage over the conventional hydraulic system.

Optimizing the Presentation of Uav Images in an Attack Helicopter Cockpit

Future Unmanned Aerial Vehicles (UAV) will collaborate more directly with military manned aircraft. TNO Defence, Security and Safety investigated how to present UAV sensor images in a fighter aircraft cockpit in order to maximize target identification and flying performance. Ten military pilots performed several Close Air Support missions in a helicopter simulator using four different display configurations. The orientation of the electronic map was either North-Up or Heading-Up. The UAV sensor image was either non-aligned (unadjusted image orientation: the image is presented as seen from the UAV viewpoint), or aligned with the orientation of the electronic map (adjusted image orientation, either resulting in a North-Up orientation or a Heading-Up orientation with respect to the helicopter, depending on the orientation of the electronic map). The pilots reported that they generally preferred the aligned UAV sensor image in combination with a Heading-Up map. This preference was reflected in their performance: targets were identified twice as fast, and the waypoint trajectory was flown more efficiently.

Image-Based Modeling of Urban Buildings Using Aerial Photographs and Digital Maps

A VR (virtual reality) simulator which is used for helicopter simulations requires a virtual environment of real world urban areas. However, real urban environments are continuously changing. It is necessary to develop a modeling method that makes direct use of GIS (geographical information system) data which is updated periodically. A flight simulation needs to visualize not only buildings in the near distance but also a large number of buildings in the far distance. We propose a method for modeling urban environments from aerial images and digital maps with relatively little manual work. An image-based method is applied to the urban modeling that considers the characteristics of Korean cities. Buildings in the distance can be presented without creating a large number of polygons. The proposed method consists of a pre-processing stage that prepares the model from the GIS data and a modeling stage that creates the virtual urban environment. The virtual urban environment utilizes the height map of buildings.

Implementation of a Free-Vortex Wake Model in Real-Time Simulation of Rotorcraft

Free-vortex wake models are capable of providing an accurate and physically detailed representation of the main rotor wake for flight dynamics simulation. Recent advances in computing power and efficient algorithms have made it feasible to use free wakes for real-time simulation. The CHARM free-vortex wake model was integrated with the GENHEL flight dynamics simulation of the UH-60A helicopter. A high fidelity wake model was defined by increasing the spatial and temporal resolution of the wake until a converged response was observed, but this baseline model could not execute in real-time. A parametric study was performed to find the best combination of wake parameters to achieve real-time execution with minimal deviation from the baseline model in terms of the frequency and time responses in the pitch and roll axes. A real-time model was found and showed reasonable agreement with the baseline model as compared to a simple finite-state inflow model. A parallel implementation of the free wake model was also investigated. An increase in computational efficiency could be achieved using a distributed processing approach with asynchronous communications.

Closed-Loop Aeromechanical Stability of Hingeless Rotor Helicopters with Higher Harmonic Control

The development of a state-space formulation for a multi-input/multi-output (MIMO) higher-harmonic-control (HHC) system is described. Results are also presented of a numerical investigation into closed-loop performance and stability of an HHC system, implemented in the rotating system, based on the simulation of a hingeless rotor helicopter. The results show that the HHC controller reduces the 4/rev accelerations at the center of gravity. The percentage reductions obtained in the simulations are in excess of 80-90 %. The vibration attenuation occurs within 5-7 s after the HHC system is turned on. This is equivalent to a frequency of around 1 rad/s, where flight control systems and human pilots tend to operate. Therefore, interactions and potential adverse effects on the stability and control characteristics of the helicopter should be explored. The HHC problem is intrinsically time periodic if the HHC inputs include frequencies other than the frequency one wishes to attenuate. This is true even if the rest of the model is assumed to be time invariant. In these cases, the closed-loop stability results obtained using constant coefficient approximations can be incorrect even at lower values of the advance ratio μ, where constant coefficient approximations of the open-loop dynamics are accurate.

FHS, the new research helicopter: Ready for service

The DLR Flying Helicopter Simulator (FHS) has been taken into service by the end of 2002. A standard EC135 helicopter was significantly modified. In particular, the mechanical control system was replaced by a full authority fly-by-light control system. A specific system architecture was defined consisting of a multiple redundant core system, meeting the highest safety level, and a simplex experimental system giving the flexibility for easy adaptations. These characteristics together with an extensive instrumentation make the FHS a suitable tool for various applications. The helicopter was developed and financed in a co-operative effort by the DLR, Eurocopter Germany, Liebherr Aerospace, and the German Ministry of Defence. It was designed to support national and international research and technology programs. It is operated by the DLR in Braunschweig, where also the FHS related ground stations are located: a ground based system simulator and transportable telemetry and data evaluation stations. The paper first concentrates on the presentation of the FHS system philosophy and design. It explains the FHS operational modes and presents the ground facilities. Then, it gives an overview on the present user programs and finally presents an outlook on future extensions of the FHS.

Muscle Oxygenation Changes Of Pilotʼs Trapezius Muscles During Military Day And Night-vision Helicopter Simulator Missions

Muscle Oxygenation Changes Of Pilotʼs Trapezius Muscles During Military Day And Night-vision Helicopter Simulator Missions

State-Space Representation of Vortex Wakes by the Method of Lines

The method of lines (MOL) is applied to the equations of helicopter rotor vortex wakes, and converts the governing partial differential equations into a system of ordinary differential equations (ODE). These ODE can then be coupled to other ODE modeling helicopter dynamics, for time-marching simulations or to extract linearized models. The MOL is applied to a simplified set of wake equations that has an analytical solution. Because these simplified equations neglect key wake physics, the study is only a first step toward applying MOL to realistic models. Therefore, the conclusions only apply to the simplified problem considered. The results show that the MOL is a suitable method to formulate vortex wake models in state-space form. The solutions are accurate and numerically stable. Refining the space discretization increases the stiffness of the ODE, but explicit solvers can still be used. Computational efficiency increases when the accuracies of space and time discretizations are matched, that is, the local error tolerance set for the time solver is matched with the order of accuracy of the space discretization. Formulas of several orders were used in the space discretization. In all cases, the explicit ODE solver used (DE/STEP) was much more computationally efficient than another, implicit ODE solver (DASSL). Linearized state-space wake models can be easily obtained. The MOL could also provide a systematic methodology to extract state-space models from computational fluid dynamics formulations, and therefore to increase the accuracy of helicopter simulation models.

Detection and Avoidance of Main Rotor Hub Moment Limits on Rotorcraft

There is interest in developing carefree maneuvering capability on future rotorcraft. This has driven the need for advanced algorithms that predict the onset of structural limits and cue the pilot using tactile feedback. A new method is presented for the detection and avoidance of static load limits on the main rotor hub. An algorithm was developed that uses linear models to estimate constraints on longitudinal and lateral cyclic stick positions that ensure the transient response of hub moments remain bounded within prescribed limits. The system was tested using a high-fidelity nonlinear simulation of a UH-60A helicopter (GENHEL). The system was shown to be successful in simultaneously constraining stick travel in both lateral and longitudinal axes to prevent hub moment limit violations. The most critical conditions occurred during control reversals, at which point the system effectively imposed rate limits on the stick motion. The algorithm was shown to be robust to changes in aircraft weight and c.g. location.

A Tactile Cockpit Instrument to Support Altitude Control

We tested the effect of a tactile torso display on keeping an instructed altitude during low level flight. The tactile instrument consisted of 64 vibrating elements attached to the torso, shoulders and thighs of the pilot. In a helicopter simulator, 12 student pilots flew under different conditions of vision (full vision and night vision) and the tactile instrument (none, a simple version and a complex version). The simple version presented the direction of the desired altitude. The complex version added the current motion direction. The participants performed an additional cognitive task during half of each scenario. We analyzed performance and subjective mental effort ratings. The results showed that the tactile instrument halved the altitude error without effecting the mental effort rating. This effect was present in full vision and in night vision conditions. There were no differences between both versions of the tactile instrument. We conclude that this emerging technology is a powerful support in a low-level flight without enlarging the pilot's mental effort.

Flight simulation in academia HELIFLIGHT in its first year of operation at the University of Liverpool

AbstractThe challenges of helicopter simulation are being tackled across a broad front as technology is developed to meet the needs of Industry. Traditionally, the strongest impetus has come from the training community and this is likely to continue for some time as simulation technology advances at increasing pace, raising fidelity standards. The development of PC-based simulation technologies is providing a significant spur in this development and lowering the cost, making complete simulation systems of reasonably high fidelity available to smaller organisations. This paper describes the first year of operation with such a system at the University of Liverpool – HELIFLIGHT. With its full motion, wide field-of-view visuals, programmable force-feel system and the comprehensive FLIGHTLAB modelling environment, we describe the HELIFLIGHT system as high fidelity and the first year of utilisation saw extensive use in a variety of handling qualities and pilot-vehicle technology research and teaching. Some of these are described in the paper and from a year of many highlights, the EU-funded programme to develop handling qualities for a civil tilt rotor aircraft is selected to demonstrate the versatility of the HELIFLIGHT system.