Air Vehicle Simulator Research Articles

Design and Assessment of Fighter Pilot Assistance Systems for Air-to-Air Refuelling with Probe-and-Drogue-Equipment

Air-to-air refuelling (AAR) with a probe-and-drogue system is a highly demanding process for fighter pilots. In the frame of the project “Future Air-to-Air Refuelling” (F(AI)2R) the German Aerospace Center (DLR) is designing concepts for assistance systems to support fighter pilots during this manoeuvre. The AAR process was examined using a hierarchical task analysis (HTA) based on a literature review and semi-structured interviews with Eurofighter-, Tornado- and test pilots. “Situation Awareness Requirements” (SAR), which represent relevant parameters for the situation awareness of the fighter pilot were derived from the HTA and rated by pilots according to their relevance. The collected data was then used to design different concepts of pilot assistance systems using a morphological box and a decision matrix. The concepts were visualised as storyboards, assessed by test pilots of the “Wehrtechnische Dienststelle 61” (WTD 61) and optimized based on their feedback. In this paper, the used methodology as well as the results of the HTA and SAR analysis are presented. Besides that, storyboards for pilot assistance systems displaying the overtake speed “German Patent No. 10.2022.110.505” and the “Contact Assistance, Status and Warning System” (CASWS) “German Patent No. 10.2022.123.653” are described. Additionally, the planned implementation using a HoloLens 2 is explained and the strategy for the subsequent simulator study on the DLR fighter aircraft simulator “Military AiR vehicle Simulator – Fast Integration Testbed” (MARS-FIT) is described.

Implementation of a toolbox for the generation of flight profiles for use in simulator studies

Motion sickness is a phenomenon which can produce various symptoms in affected individuals. During development of new aircraft types and cabin layouts, it is important to consider this phenomenon early on, to reduce resulting effects. For research on this topic, German Aerospace Center uses the simulator environment Air Vehicle Simulator together with the Advanced Future Cabin. The Air Vehicle Simulator is a full flight simulator with an interchangeable cockpit module. One of those modules is the Advanced Future Cabin, a realistic replica of an aircraft cabin. Good standardization of the test conditions is required to ensure objectivity and reliability of motion sickness studies in this simulator environment. A specialized software infrastructure is used to replay pre-recorded flight profiles, which are then reproduced by the simulator’s motion, visual and audio systems. Using this replay approach, complete flight profiles can be reproduced very well. However, when parts of the flight profile need exact reproduction within a flight profile or across multiple flight profiles, the approach to record pilot-in-the-loop simulation sessions becomes problematic, as flying the exact same twice is almost impossible. As an improved approach, a toolbox has been implemented, which automates the generation of flight profiles, enabling easier and more precise research on motion sickness in the simulator. The toolbox replaces the pilot-in-the-loop simulation with an automated control of the underlying aircraft simulation model. This leads to greatly improved accuracy of inputs to the simulation model and thus very good reproducibility even of flight profile segments. In this manuscript, details of the toolbox implementation and its validation are discussed.

Evaluation of a real-time simulation environment for helicopter air-to-air refuelling investigations

AbstractThe ability to perform air-to-air refuelling (AAR) can dramatically extend the utility of helicopters, through effectively providing unlimited range. For helicopters, AAR is typically performed utilising the probe-and-drogue aerial refuelling method. This is a complex manoeuver, where normally both the helicopter and tanker aircraft are operating at the limits of their flight envelopes. In addition, the wake flow from the tanker aircraft can cause a significant disturbance on the refuelling helicopter. This paper presents the initial evaluation of an AAR scenario constructed within DLR’s flight simulator, the Air Vehicle Simulator (AVES), based on current procedures and pilot interviews. A mission task was defined to assess the scenario in AVES and results are subsequently discussed. For pilots unfamiliar to formation flight or HAAR, the results show the difficulty of the flying task itself at the given cueing. Measures for improvement in future investigations are suggested.

Using augmented reality to reduce workload in offshore environments

In the offshore environment helicopters are widely used to transport crew and material from and to maritime wind farms. Due to unforeseeable and often inclement weather situations and challenging tasks these missions put a high workload on the helicopter pilots. In this paper two test campaigns are described which assess the utility of an affordable commercial-off-the-shelf (COTS) head-mounted display (HMD) to reduce workload for commercial maritime operations. The HMD system was implemented within the air vehicle simulator (AVES) at the German Aerospace Center (DLR). Three missions were flown with experienced offshore pilots, performed in a realistic scenario. Independent subjective assessments of both workload and situational awareness were obtained. Results from the studies show that the overall workload for all missions decreased and situational awareness increased when using the HMD. Opinions regarding overall benefit and advantages of the system were found to vary between pilots and missions.

Individual differences in the temporal progression of motion sickness and anxiety: the role of passengers’ trait anxiety and motion sickness history

The objective of the study is to show that trait anxiety and motion sickness history are responsible for different temporal progressions of sickness in passengers. The level of inflight anxiety and inflight sickness severity was monitored for 124 passengers in a full-motion cabin simulator during a short-haul flight with four different flight segments. Four groups with different characteristics in trait anxiety and motion sickness susceptibility showed different profiles of inflight sickness development. High trait anxiety was responsible for high inflight anxiety and a constantly high level of motion sickness, while passengers with just a motion sickness history showed an increase in motion sickness severity over time. We suggest that trait anxiety and motion sickness susceptibility interact and have an impact on the temporal progression of inflight sickness severity. The analysis of temporal developments of anxiety and sickness are fruitful for understanding the origins of motion sickness, research and individual treatments. Practitioner summary: In a full-motion cabin simulator study with 124 passengers the level of inflight anxiety and inflight sickness severity was monitored. Trait anxiety and motion sickness history were found to have different impacts on the temporal progression of individual sickness severity. Abbreviations: ANOVA: analysis of variance; AVES: air vehicle simulator; hiA/hiM: group with high anxiety and high motion sickness susceptibility; hiA/loM: group with high anxiety and low motion sickness susceptibility;MSSQ: motion sickness susceptibility scale; loA/hiM: group with low anxiety and high motion sickness susceptibility; loA/loM: group with low anxiety and low motion sickness susceptibility; SPSS: statistical package for the social sciences; SSQ-TS: total score from the simulator sickness questionaire; STAI: state trait anxiety inventory

Integration and use of an augmented reality display in a maritime helicopter simulator

Operating a helicopter in offshore wind parks with degraded visual environments from clouds or fog can endanger crew and material due to the presence of unseen obstacles. Utilizing on-board sensors such as LIDAR or radar, one can sense and record obstacles that could be potentially dangerous. One major challenge is to display the resulting raw sensor data in a way that the crew, especially the pilot, can make use of it without distracting them from their actual task. Augmented reality and mixed reality applications play an important role here. By displaying the data in a see-through helmet-mounted display (HMD), the pilot can be made aware of obstacles that are currently obscured by degraded visual conditions or even parts of the helicopter. This can be accomplished in one HMD. No attention sharing between the outside view and a head-down instrument is necessary. The German Aerospace Center (DLR) is continuously aiming at testing and evaluating both flight-proof and consumer grade HMDs. One particular widely known system is the Microsoft HoloLens. DLR will integrate this low-cost HMD into their experimental helicopter. For this, as a first step, a Microsoft HoloLens was integrated into DLR’s Air Vehicle Simulator (AVES). The integration process is detailed. The simulation capabilities are described, especially for conformal, open-loop LIDAR sensor data. Furthermore, first concepts of the display format are shown, and strengths and drawbacks of the HoloLens in a cockpit environment are discussed.

Motion cueing optimisation applied to rotorcraft flight simulation

Achieving good motion cueing in rotorcraft flight simulation is a long-standing challenge in the simulation community. The current reliance upon subjective opinion leads to a wide range of motion configurations, which almost certainly do not offer the optimal level of vestibular cueing. Furthermore, without the understanding of the optimal motion settings, objective criteria are difficult to apply. This paper presents a new method designed to optimise and evaluate the response of any motion platform, based upon the input to the system and the given motion system constraints. The method is utilised to tune the motion platform of the air vehicle simulator. Results show promise for the use of the optimisation, as good fidelity is shown through pilot subjective comments and ratings.

Impact of turbulence and degraded visual environment on pilot workload

Offshore helicopter operations are frequently conducted in both turbulent and degraded visual environments (DVE). This investigation assesses the combined influence of turbulence and DVEs on pilot workload to identify first limits for safe operations. Flight tests using a simulation model of the research helicopter ACT/FHS (active control technology/flying helicopter simulator) flight mechanics model were conducted in the air vehicle simulator (AVES) at DLR Braunschweig. Tests were completed using four pilots, and results show the effects on pilot workload, task performance and control input activity. It was found that DVE and turbulence increase the workload and reduce task performance, but each in a different manner. Furthermore, the impact on control activity and pilot-induced oscillation tendencies are shown to have dependency upon the environmental conditions.

Handling qualities evaluation of an automatic slung load stabilization system for rescue hoist operations

The Handling Qualities (HQs) of a helicopter can be adversely affected through the presence of an externally slung load. Helicopter stability margins may be reduced, due to the additional dynamics of the load system, which can subsequently increase pilot workload, and reduce the operational envelope. An Automatic Load Damping System (ALDS) has been designed and has been successfully tested in flight. This system, alongside slung load scenarios, has been implemented within a piloted simulation in DLR’s Air Vehicle Simulator. In this article, the results from a simulated test campaign to observe the influence of the stabilization system on the vehicle HQs are presented. The system is assessed using three Mission Task Elements, modified for hoist operations. Results show that a conflict between pilot control and commanded inputs from the ALDS can cause unstable slung load oscillations and degradation in HQs in hover. However, it is shown that when the stabilization system is used only when required, both the HQs of the helicopter are conserved, and load oscillations are reduced. The results in this paper are intended to motivate future flight tests using DLR’s Active Control Technology/Flying Helicopter Simulator.

Imperfect Diagnostic Automation: An Experimental Examination of Priorities and Threshold Setting

Diagnostic automation, such as alarms, alerts, or automatic target recognition systems can vary in their reliability and threshold setting, the latter influencing the balance between misses and false alarms. This experiment examined the implications of both of these, when the system detected military targets in parallel with the human operator in an unmanned air vehicle simulator. Unlike previous investigations of this paradigm in a dual task setting, the automation diagnosis task was very difficult, and priority between this task and a concurrent task was explicitly varied, along with the threshold setting. The results revealed that: (a) reliability as low as 0.6 aided human performance. (b) the effects of the automation threshold shift could be partially modeled in terms of the classic reliance-compliance dimensions of automation dependence, at both task priority settings. (c) The priority effects were more pronounced with miss-prone automation. (d) directing attention to false-alarm prone automation actually degrades human-system performance.

Psychophysiologically Determined Classification of Cognitive Activity

Psychophysiological measures and artificial neural networks were used to determine how well higher levels of cognitive activity, such as executive function, spatial and verbal working memory and global workload, could be assessed. A complex uninhabited air vehicle simulator was used in which subjects were responsible for four vehicles simultaneously. The subjects had to evaluate visual images and maintain the status of the vehicles. The results showed that the cognitive states, derived from subjective reports, could be accurately classified. These results have application in human factors environments which demand higher level cognitive processing and may be useful when implementing adaptive aiding in these systems.