Helicopter Simulator Research Articles

The Effectiveness of Sensor Visualizations and Graphic Augmentations for Detecting Vertical Obstacles

Slow or failed detection of low‐salience vertical obstacles and associated wires is one of today’s leading causes of fatal helicopter accidents. The risk of collisions with such obstacles is likely to increase as advanced aerial mobility and broadening drone activity promises to increase the density of air traffic at low altitudes, while growing demand for electricity and communication will expand the number of vertical structures. The current see‐and‐avoid detection paradigm relies on pilots to spend much of their visual attention looking outside for obstacles. This method is inadequate in low‐visibility conditions, cluttered environments, and given the need for pilots to engage in multiple competing visual tasks. With the expected growing number of hazards and an increased traffic volume, the current approach to collision avoidance will become even less tenable. A human‐in‐the‐loop helicopter simulator study was conducted to assess the effectiveness of sensor visualizations (image intensification or thermal imaging) and graphic augmentations (a bounding box around a tower and a circle surrounding the base of the tower) for supporting fast and reliable detection of vertical structures. Graphic augmentations resulted in faster tower detection time when ambient visibility and illumination were reduced close to the limit for visual flight. Bounding boxes around towers were detected first in all conditions but tended to mask the obstacle they were meant to highlight. Sensor visualization affected tower detection time only at night, where night vision goggles were more effective than the infrared thermal sensor.

Black Hawk 70i Helicopter Crew Simula- tion Training

Over the past several decades, fl ight simulators have played an important role in pilot training for both civilian and military aircraft. There are fi nancial considerationsbehind the production or purchase of fl ight simulators. Although the initial fi nancial contribution is high, in the long run the use of simulation systems is more cost-effective than real-world pilot training. Furthermore, the service’s limited fi nancial resources may cause it to halt or limit the amount of real-world training it receives. The cost of aviation fuel causes drastic reductions in training time for helicopter crews (police, military or civilian). Consequently, alternative methods of training personnel using aircraft have become the focus of the search for new solutions. One example being built is the Helicopter Simulator for Police Aviation. The implementation of the Police Aviation Helicopter Simulator into the police training system will enable the proper preparation of Police Aviation crews and counterterrorism units of the Police to perform their tasks profi ciently and effectively. The information presented in thisarticle is the result of analysis of the source data obtained from the design documentation of the “Helicopter Simulator for Police Aviation” No. DOB-BIO10/07/01/2019. One undeniable research limitation was the inability to provide in this study a detailed description of the simulator due to reservations related to protection of Intellectual Property Rights, which were included in the contracts for the execution and fi nancing of the project.

VAST as a generic, modular aeromechanics code for wind turbine simulation

In order to leverage the full potential wind energy, more research is needed both in the field and numerically. At DLR, the need for simulation competencies is expected to be met by the in-house developed generic and highly flexible multi-physics code VAST. While initially aimed at low- to medium-fidelity simulations of helicopter aeromechanics, the code is applicable to other problems like wind turbine computations. The goal of this paper is to present the general concept of VAST and briefly introduce the available physics models. Next to examples of successful application to helicopter simulation problems, first results in the field of wind energy are shown. The well-known IEA 15 MW reference wind turbine is used as a basis to compare VAST — both with a BEMT and a vortex theory inflow model — to other tools with similar and higher-fidelity physics modeling. For the rigid turbine, blade loads are compared with results of other tools using engineering models as well as CFD, showing good overall agreement. A more detailed evaluation of aerodynamic quantities like the angle of attack and the induced velocity field is presented for VAST and the CFD results. An outlook on the ongoing VAST developments is given.

Helicopter Pilot Performance and Workload in a Following Task in a Degraded Visual Environment.

BACKGROUND: In this study, we investigated the impact of a loss of horizon due to atmospheric conditions on flight performance and workload of helicopter pilots during a low-altitude, dynamic flight task in windy conditions at sea. We also examined the potential benefits of a helmet-mounted display (HMD) for this specific task.METHODS: In a fixed-based helicopter simulator, 16 military helicopter pilots were asked to follow a maneuvering go-fast vessel in a good visual environment (GVE) and in a degraded visual environment (DVE). DVE was simulated by fog, obscuring the horizon and reducing contrast. Both visual conditions were performed once with and once without an HMD, which was simulated by projecting head-slaved symbology in the outside visuals. Objective measures included flight performance, control inputs, gaze direction, and relative positioning. Subjective measures included self-ratings on performance, situation awareness, and workload.RESULTS: The results showed that in DVE the pilots perceived higher workload and were flying closer to the go-fast vessel than in GVE. Consequently, they responded with larger control inputs to maneuvers of the vessel. The availability of an HMD hardly improved flight performance but did allow the pilots to focus their attention more outside, significantly improving their situation awareness and reducing workload. These benefits were found in DVE as well as GVE conditions.DISCUSSION: DVE negatively affects workload and flight performance of helicopter pilots in a dynamic, low-altitude following task. An HMD can help improve situation awareness and lower the workload during such a task, irrespective of the visual conditions.Ledegang WD, van der Burg E, Valk PJL, Houben MMJ, Groen EL. Helicopter pilot performance and workload in a following task in a degraded visual environment. Aerosp Med Hum Perform. 2024; 95(1):16-24.

Comparison of vestibular input statistics during natural activities and while piloting an aircraft.

The present study investigates the statistics and spectral content of natural vestibular stimuli experienced by healthy human subjects during three unconstrained activities. More specifically, we assessed how the characteristics of vestibular inputs are altered during the operation of a complex human-machine interface (a flight in a helicopter simulator) compared with more ecological tasks, namely a walk in an office space and a seated visual exploration task. As previously reported, we found that the power spectra of vestibular stimuli experienced during self-navigation could be modeled by two power laws but noted a potential effect of task intensity on the transition frequency between the two fits. In contrast, both tasks that required a seated position had power spectra that were better described by an inverted U shape in all planes of motion. Taken together, our results suggest that 1) walking elicits stereotyped vestibular inputs whose power spectra can be modeled by two power laws that intersect at a task intensity-dependent frequency; 2) body posture induces changes in the frequency content of vestibular information; 3) pilots tend to operate their aircraft in a way that does not generate highly nonecological vestibular stimuli; and 4) nevertheless, human-machine interfaces used as a means of manual navigation still impose some unnatural, contextual constraints on their operators.NEW & NOTEWORTHY Building upon previously published research, this study assesses and compares the vestibular stimuli experienced by healthy subjects in natural tasks and during the interaction with a complex machine: a helicopter simulator. Our results suggest the existence of an anatomical filter, meaning that body posture shapes vestibular spectral content. Our findings further indicate that operators control their machine within a constrained operating range such that they experience vestibular stimulations that are as ecological as possible.

Spatial Disorientation Scenarios for the AW159 Helicopter Within a Synthetic Training Environment

BACKGROUND: Spatial disorientation (SD) remains a stubborn and formidable challenge among rotary wing (RW) aircrews, particularly during times of high workload and deceptive visual cues. With tri-Service agreement, British RW Forces employ a layered training approach that now includes simulator-based immersive scenarios.METHODS: Ten bespoke RW SD training scenarios were developed for the AW159 Wildcat helicopter simulator by a multidisciplinary team. Scenarios were embedded within advanced training packages that were not solely focused on SD. A voluntary, anonymous survey instrument was distributed post-SD sortie to assess hazard awareness, training effectiveness, role and mission relevance, and perceived ability to respond to future SD threat. A corresponding assessment from the simulator instructor was used for independent determination if the crew became disoriented during the training.RESULTS: Over a 6-mo training cycle, 69 surveys were completed. Seven-point Likert-scale assessments yielded elevated median scores (6.0, respectively) across all four categories, suggesting favorable aircrew perceptions of training objective success. Elevated scoring of previous SD training received suggests good penetrance among the RW community surveyed. Of all sorties flown, the majority of aircrew (68%) became disoriented at some point during the sortie.DISCUSSION: This report provides limited evidence in support of bespoke SD training scenarios within a synthetic training environment. The merits include flexible ability to address root causes, provision of an interactive and immersive environment, and compatibility with extant tactics and mission configurations. SD simulator-based training can serve as an important component of a layered, multimodal approach.Bushby AJR, Gaydos SJ. Spatial disorientation scenarios for the AW159 helicopter within a synthetic training environment. Aerosp Med Hum Perform. 2023; 94(5):377-383.

Visual augmentation of deck-landing-ability improves helicopter ship landing decisions

When attempting to land on a ship deck tossed by the sea, helicopter pilots must make sure that the helicopter can develop sufficient lift to be able to safely touchdown. This reminder of affordance theory led us to model and study the affordance of deck-landing-ability, which defines whether it is possible to land safely on a ship deck depending on the helicopter's available lift and the ship’s deck heave movements. Two groups of participants with no piloting experience using a laptop helicopter simulator attempted to land either a low-lifter or a heavy-lifter helicopter on a virtual ship deck by either triggering a pre-programmed lift serving as the descent law if it was deemed possible to land, or aborting the deck-landing maneuver. The deck-landing-ability was manipulated by varying the helicopter's initial altitude and the ship's heave phase between trials. We designed a visual augmentation making visible the deck-landing-ability, and thus enabling participants to maximize the safety of their deck-landing attempts and reduce the number of unsafe deck-landing. The visual augmentation presented here was perceived by participants as a means of facilitating this decision-making process. The benefits were found to have originated from the clear-cut distinction it helped them to make between safe and unsafe deck-landing windows and the display of the optimal time for initiating the landing.

Functional Assumptions “Helicopter Simulator for Polish Police Aviation”

The analysis of the training needs for the crews of police multi-purpose Black Hawk S70i helicopters serving in Polish Police Forces has been an impulse to attempt the construction of the simulation system within the research and development project financed by the National Centre for Research and Development entitled “Helicopter Simulator for Police Aviation” consisting of three components, i.e. a training stand for a pilot (cockpit), a stand for a cargo handler, a training stand for the police officers practicing the air drop operations. The simulator is supposed to provide an opportunity to drill various emergency situations, which consequently will allow to prepare the crews and technical personnel in the full range to perform the tasks as far as theoretical knowledge and practical skills are concerned. Replacing real exercises by the training held in virtual environment will contribute to the decreased costs to be incurred by Police and increased safety for any persons participating in the actions remaining the subject matters of the said trainings. The article presents the designing assumptions resulting, among other things, from multidisciplinary research performed over the determination of the detailed training needs and equipment requirements with regards to the Full Flight Simulator. The said research was conducted in collaboration with the officers of the Police Aviation Board in the High Command of the Police Headquarters as well as the operators of the counter terrorism sub-units of Polish Police Forces.

Tilt perception is different in the pitch and roll planes in human.

Neurophysiological tests probing the vestibulo-ocular, colic and spinal pathways are the gold standard to evaluate the vestibular system in clinics. In contrast, vestibular perception is rarely tested despite its potential usefulness in professional training and for the longitudinal follow-up of professionals dealing with complex man-machine interfaces, such as aircraft pilots. This is explored here using a helicopter flight simulator to probe the vestibular perception of pilots. The vestibular perception of nine professional helicopter pilots was tested using a full flight helicopter simulator. The cabin was tilted six times in roll and six times in pitch (-15°, -10°, -5°, 5°, 10° and 15°) while the pilots had no visual cue. The velocities of the outbound displacement of the cabin were kept below the threshold of the semicircular canal perception. After the completion of each movement, the pilots were asked to put the cabin back in the horizontal plane (still without visual cues). The order of the 12 trials was randomized with two additional control trials where the cabin stayed in the horizontal plane but rotated in yaw (-10° and +10°). Pilots were significantly more precise in roll (average error in roll: 1.15 ± 0.67°) than in pitch (average error in pitch: 2.89 ± 1.06°) (Wilcoxon signed-rank test: p< 0.01). However, we did not find a significant difference either between left and right roll tilts (p= 0.51) or between forward and backward pitch tilts (p= 0.59). Furthermore, we found that the accuracies were significantly biased with respect to the initial tilt. The greater the initial tilt was, the less precise the pilots were, although maintaining the direction of the tilt, meaning that the error can be expressed as a vestibular error gain in the ability to perceive the modification in the orientation. This significant result was found in both roll (Friedman test: p< 0.01) and pitch (p< 0.001). However, the pitch trend error was more prominent (gain=0.77 vs gain=0.93) than roll. This study is a first step in the determination of the perceptive-motor profile of pilots, which could be of major use for their training and their longitudinal follow-up. A similar protocol may also be useful in clinics to monitor the aging process of the otolith system with a simplified testing device.

Development of an MUM-T Integrated Simulation Platform

In this paper, we present a platform that can simulate Manned-UnManned Teaming (MUM-T) situations using various hardware and software being integrated. MUM-T, which combines unmanned aerial vehicles (UAVs) with an existing manned vehicle (MV), is growing into an indispensable strategy thanks to enormous advantages it provides. In order to test this indispensable strategy which involves flight control algorithms being applied for various MUM-T situations, it is certainly needed to run and evaluate three-dimensional (3D) MV-UAVs combined simulations in realistic environments. However, there is no such simulator that enables such 3D MUM-T simulations as well as the Human Interface (HI) for both MV pilot and the mission manager at a ground station. In this paper, we propose an MUM-T integrated simulation platform (MUM-T ISP) that combines a single full-scale helicopter simulator (for MV simulation) and multiple Iris/PX4-Autopilot (for UAVs simulation), along with specially developed HI devices (TM and TV). Tactical Monitor (TM), one of the HI devices, is a touchable tablet which allows the MV pilot to interact with UAVs by simple actions (e.g. touching a button), and the other HI device called Tactical Viewer (TV) allows the mission manager at a ground station to closely monitor the MUM-T situation via realistic 3D displays of MV and UAVs. The proposed MUM-T ISP is tested on several mission scenarios and then evaluated by actual pilots and the mission manager based on sensible criteria. It is expected that the proposed simulation platform may serve well as a training tool for prospective MV pilots working with UAVs, and also as a research tool for flight engineers developing control algorithms that make MV and UAVs work together.

To the problem of simulation modelling of abnormal and emergency flight situations in the process of Mi-8MTV helicopter pilot simulation training

The article examines a method of obtaining the required initial data for adequate mathematical modelling of nonstationary processes in the Mi-8MTV helicopter computer and flight simulators. The principle of the method is as follows: the video fixation of non-stationary modes of the power plant operation in a real flight and the computation of the obtained dependencies according to the known formulas of mechanics, aerodynamics, the theory of gas turbine aircraft engines, etc. are analysed. Moreover, by juxtaposing the computed dependencies and the obtained video fixation, the parameter values, that determine the helicopter power plant behaviour (the inertia moment of the helicopter main rotor system, etc.) in the non-stationary modes, are found. These parameters allow us to solve the problem by modelling a complete picture of the helicopter power plant behaviour in abnormal and emergency situations, under which, it is impossible to formulate an objective verdict without violating flight safety requirements. Given the circumstances, the feasibility of an advantageous and reliable solution to the problem is considered using mathematical modelling of the transient power plant operation modes both in non-stationary conditions and in abnormal and emergency situations. A simulation of these scenarios and responsive actions is carried out using helicopter simulators. In a real flight, a helicopter crew monitors the functional systems status and the development of abnormal and emergency situations relying on readings from dial instruments, digital indicators, annunciators, and other computer-aided facilities in the cockpit, not only by the parameter values, but also by dynamics of their variation in flight. Within this timespan, the pilot must assess an abnormal situation and decide on required actions.

Passive sound detection of the helicopter in the far-field with a spectral coherence decomposition method

Helicopter detection is an important part of the safety and security during flight. Most of the aerodynamic noise of modern helicopters comes from the main rotor, the main rotor aerodynamic noise thus can be used for helicopter detection. However, the Signal-to-Noise Ratio (SNR) of the measurement noise has always been quite small while the helicopter is flying over long distance away from the microphone. The current passive detection methods are not robust enough in the presence of substantial interference. A robust passive sound detection method is proposed to detect the far-field helicopter based on the cyclostationarity of the main rotor noise. The Sparsity-Enhanced Spectral Coherence (SESC) is derived from the spectral coherence decomposition to improve the detection robustness at far distances and low SNR. Furthermore, a global detector is constructed to detect helicopters adaptively by fusing the detection of multiple orders of BPF, which can be performed on the calculated SESC. More accurate and robust detection of the far-field helicopter can be obtained by the proposed SESC detector. The effectiveness of the proposed detection approach is demonstrated and contrasted by using simulation and far-field flight test measurements of the ROBINSON R22 helicopter.

A Turbulence Model for Flight Simulation and Handling Qualities Analysis Based on a Synthetic Eddy Method

A turbulence model based on a synthetic eddy method (SEM) has been adapted for flight simulation purposes and coupled with a FLIGHTLAB helicopter simulation model. The SEM is based on the generation of a random distribution of turbulence-generating eddies within a control volume surrounding the simulated aircraft. Eddies are displaced by the flow and regenerated at the inflow as they leave the simulation domain. The model allows adjustment of turbulence intensity and frequency spectra, allowing for a more realistic representation of broadband turbulence. Compared to other random turbulence models, preserving the location of the eddies in the control volume automatically ensures that turbulence across different aircraft locations is automatically correlated. Off-line and piloted flight simulation assessments have been conducted to test the viability of the SEM concept in flight simulation. Results show that the turbulence model generates upsets in all aircraft axes resulting in higher workload requirements for the pilot.

FUNCTIONAL ASSUMPTIONS FOR THE “HELICOPTER SIMULATOR FOR POLICE AVIATION”

An analysis of training needs for the crews of police multi-purpose Black Hawk S70i helicopters serving in Polish Police Forces has been an impulse to attempt the construction of the simulation system within the research and development project financed by the National Centre for Research and Development entitled “Helicopter Simulator for Police Aviation” consisting of three components, i.e. a training stand for a pilot (cockpit), a stand for a cargo handler, a training stand for the police officers practicing the air drop operations. The simulator is supposed to provide an opportunity to drill various emergency situations, which consequently will allow preparing the crews and technical personnel in the full range to perform the tasks as far as theoretical knowledge and practical skills are concerned. Replacing real exercises by training held in a virtual environment is expected to contribute to a decrease in costs to be incurred by Police and enhanced safety for any persons participating in the actions remaining the subject of the said trainings. The article presents the design assumptions that arise, among other things, from multidisciplinary research performed over the determination of the detailed training needs and equipment requirements with regards to the Full Flight Simulator. The said research was conducted in collaboration with the officers of the Police Aviation Board in the High Command of the Police Headquarters as well as the operators of the counter terrorism sub-units of Polish Police Forces.

Vibration Control of a Helicopter Rescue Simulator on a Flexible Base.

The vibration compensation control of a hovering helicopter rescue simulator mounted on a crane beam is studied in this research. A Stewart platform is used as the motion generator of the helicopter simulation cabin and the vibration compensation device of the beam, simultaneously. This study describes how the dynamic model of the Stewart platform with consideration of the beam vibration is established. To determine the interference of the Stewart platform motion control in the special application of a large component flexible base requiring large-scale movement, a hybrid vibration controller composed of a feed-forward compensation module and a PD (proportional-derivative) feedback control module is designed. The experimental results show that this method can effectively compensate for the beam vibration and improve the accuracy of the motion reproduction of a helicopter simulation cabin.

Piloted Simulation of the Rotorcraft Wind Turbine Wake Interaction during Hover and Transit Flights

Helicopters are used for offshore wind farms for maintenance and support flights. The number of helicopter operations is increasing with the expansion of offshore wind energy, which stresses the point that the current German regulations have not yet been validated through scientific analysis. A collaborative research project between DLR, the Technical University of Munich, the University of Stuttgart and the University of Tübingen has been conducted to examine the sizes of the flight corridors on offshore wind farms and the lateral safety clearance for helicopter hoist operations at offshore wind turbines. This paper details the results of piloted helicopter simulations in a realistic offshore wind farm scenario. The far-wake of rotating wind turbines and the near-wake of non-rotating wind turbines have been simulated with high-fidelity computational fluid dynamics under realistic turbulent inflow conditions. The resulting flow fields have been processed by superposition during piloted simulations in the research flight simulator AVES to examine the flight corridors in transit flights and the lateral safety clearance in hovering flights. The results suggest a sufficient size for the flight corridor and sufficient lateral safety clearance at the offshore wind turbines in the considered scenarios.

Configuration system design and longitudinal flight simulation verification of variable stability helicopter

For in-flight simulation of variable stability helicopter, how to have the ability to change a wide range of response characteristics and ensure flight safety is an important design problem. This paper proposes configuration design technology of the variable stability helicopter, which purpose is to safely change steady-state and dynamic response characteristics of the variable stability helicopter, and make the pilot feel good or poor helicopter response characteristics. The configuration control system of the variable stability helicopter is designed theoretically, and the configuration switch logic is studied from the perspective of flight safety. The numerical simulation test of the longitudinal configuration control law was carried out, and the configuration control law and configuration switch logic were added to the ground closed-loop test to verify. The results show that the expected response characteristics of the helicopter are obtained by applying the configuration system design technology.

Multi-screen dynamic viewpoint system for helicopter simulator

Multi-screen dynamic viewpoint system for helicopter simulator

Flying a helicopter with the HoloLens as head-mounted display

We describe the flight testing and the integration process of the Microsoft HoloLens 2 as head-mounted display (HMD) with DLR’s research helicopter. In the previous work, the HoloLens was integrated into a helicopter simulator. Now, while migrating the HoloLens into a real helicopter, the main challenge was the head tracking of the HoloLens, because it is not designed to operate on moving vehicles. Therefore, the internal head tracking is operated in a limited rotation-only mode, and resulting drift errors are compensated for with an external tracker, several of which have been tested in advance. The fusion is done with a Kalman filter, which contains a non-linear weighting. Internal tracking errors of the HoloLens caused by vehicle accelerations are mitigated with a system identification approach. For calibration, the virtual world is manually aligned using the helicopter’s noseboom. The external head tracker (EHT) is largely automatically calibrated using an optimization approach and therefore, works for all trackers and regardless of its mounting positions on vehicle and head. Most of the pretests were carried out in a car, which indicates the flexibility in terms of vehicle type. The flight tests have shown that the overall quality of this HMD solution is very good. The conformal holograms are almost jitter-free, there is no latency, and errors of lower frequencies are identical with the performance that the EHT can provide, which in combination greatly improves immersion. Profiting from almost all features of the HoloLens 2 is a major advantage, especially for rapid research and development.

Novice and experienced hoist operators in a helicopter hoist virtual reality simulator

ABSTRACT Virtual reality (VR) simulation training for helicopter search and rescues (SAR) hoist operators is very uncommon in comparison to the availability of pilot simulation training. SAR hoist operators control winch systems for hoisting objects or people during helicopter flight. Using a rear crew helicopter VR training simulator we sought to quantify hoist operator performance and validate this system by showing that experienced SAR hoist operators and novices hoist differently. We recruited 12 military SARs and 11 persons without hoisting experience and examined their performance in moderate wind conditions over two landscapes, ocean and land. Experienced operators were not affected by environment, completed missions faster than novices, made fewer velocity adjustments, and demonstrated better cable management. These variables can now be used as sources of feedback to train novice hoist operators. Since there were differences between performances of experienced and novice hoist operators we have established construct validity of the simulator.