Rotorcraft Research at the NASA Vertical Motion Simulator

CEAS Aeronautical Journal, 2013

Good visual cues are necessary in the flight simulation of ship-borne helicopter operations. Operating in a degraded visual environment cues has a negative impact on pilot workload and task performance. However, the need for motion cues in piloted flight simulation is still a widely debated issue. This paper describes a preliminary piloted flight simulation study into the effects of visual and motion cues on the operation of ship-borne helicopters and pilot workload. Unsteady CFD airwakes have been computed and integrated into the FLIGHTLAB modelling and simulation environment with a simulated rotorcraft model, configured to be representative of an SH-60B helicopter. A series of ship-deck landing and hover manoeuvres have been conducted using the University of Liverpool's HE-LIFLIGHT-R motion-base flight simulator representing different visual and motion cues, for a range of ship airwakes and sea states (ship deck motions). The usable cue environment (UCE), handling quality and pilot workload ratings were assessed using visual cue ratings, handling quality rating and the Bedford workload rating scale and Deck Interface Pilot Effort Scale. This paper presents the results from simulation trials with two test pilots examining the effect of the simulation cueing on task performance and workload. Visual cues were found to have a significant impact both on the UCE ratings and pilot workload ratings. In degraded visual environments, the pilot's ability to make corrections in attitude and translational rates was reduced. Pilots experienced higher workload in terms of compensatory control inputs to complete the same mission task as compared to operations in a good visual environment. Analysis of the pilots' workload ratings and control activity show that motion cueing can cause differences in pilot perceived workload. For the simulation of ship-borne operations, the impacts of motion cueing are dependent on other simulation conditions, which include visual environments, airwake, sea states and ship deck motion. The effect of motion cueing on pilot workload and control activity was found to be more significant when the visual cueing was degraded. The variations in pilot workload ratings and control activities under different motion and visual cues indicate that the Ship Helicopter Operating Limits can be affected by the simulation cueing fidelity.

2009

Even though simulators are often used in flight training, the effects of the different motion components on pilot performance and control behaviour are still not fully understood. In most hexapod motion base simulators the translational motion needs to be reduced significantly to fit within the limited motion space, while the rotational motion might not need attenuation. This paper presents the results of an experiment that investigated the effects of simulator motion in a roll-lateral helicopter control task for both agile and inert helicopter dynamics. The experiment was performed in the MPI Motion Simulator, which has the unique ability of presenting the motion in this task 1-to-1. The results indicate that both roll and lateral motion are important for increasing performance in reducing the roll error. The lateral motion also significantly reduced the lateral tracking errors. Pilots increased their control activity, but had a lower performance in reducing the lateral error for the inert helicopter dynamics. These effects in performance and control activity were caused by a change in the pilots' control strategy as was observed from the multimodal pilot model parameters. The effects on pilot tracking performance were also apparent from a significant change in the disturbance and target open-loop characteristics.

2018

The UK’s Royal Navy and Royal Fleet Auxiliary regularly perform launch and recovery operations of helicopters to and from their ships. These operations are carried out in challenging conditions such as confined ship deck space, irregular ship motion, sea spray and unsteady airflows, posing a high risk to the helicopter, ship and the crew. Together these elements form the Helicopter Ship Dynamic Interface (HSDI) environment (Ref. 1). To determine the limitations of the safe operability of helicopters to ships, a safety envelope is constructed through First-of Class Flight Trials (FOCFT) for every combination of helicopter/ship, to determine Ship Helicopter Operating Limits (SHOL) (Ref. 2), which detail the safe environmental conditions for launch and recovery operations. FOCFTs are performed at sea and are inevitably very expensive, which can typically take weeks to construct a SHOL envelope and very often the required wind and sea conditions may not be available, resulting in the de...

2019

Confidence 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...

2010

Flight simulators are integral to the design/development, testing/qualification, training and research communities and their utilisation is expanding rapidly. The quantification of simulation fidelity underpins the confidence required for the use of flight simulation in design, to reduce real life testing, and to provide a safe environment for pilot training. Whilst regulatory simulator standards exist and new standards are in development, previous research has shown that current standards do not provide a fully quantitative approach for assessing simulation fidelity, even in a research environment. This paper reports progress on developments of the HELFLIGHT-R flight simulator at the University of Liverpool, and its subsequent use in a research project (Lifting Standards) aimed at creating new predicted and perceived measures of simulator fidelity, derived from handling qualities engineering. Results from flight tests on the National Research Council (Canada) Bell 412 ASRA research aircraft and HELIFLIGHT-R piloted simulation trials are presented to show the strong connection between handling qualities engineering and fidelity assessment. The issue of (pilot) perceived fidelity is examined and the development of new metrics discussed. NOTATION CP  CP  , CP  Roll, pitch yaw Control Power (°/s) Height rate (ft/s) p, p pk Roll rate, peak roll rate (°/s) Roll, pitch, yaw quickness (/s) q, q pk Pitch rate, peak pitch rate (°/s) r, r pk Yaw rate, peak yaw rate (°/s) r (1) , r (3) Yaw rate at 1s, 3s (°/s) T hdot Time constant (s) Xa Pilot lateral control (inch) Xb Pilot longitudinal control (inch) Xc Pilot collective control (inch) Xp Pilot pedal control (inch)   Damping  Pilot control deflection (nd) θ,ψ Pitch, roll, yaw attitude (°)  hdot Response delay time (s)  p  p   Roll, pitch, yaw phase delay (s)  p  p   Roll, pitch, yaw bandwidth (rad/s) ACRONYMS ACAH

Once the military helicopter pilot deploys aboard a naval vessel he leaves behind all training platforms, short of the actual aircraft, that present enough fidelity for him to maintain the highest levels of readiness. To that end, this thesis takes a preliminary step in creating a trainer that places the pilot in an immersive and familiar environment to exercise myriad piloting tasks as faithfully and as rigorously as in actual flight. The focus of this thesis it to assess the viability of an chromakeyed augmented virtual environment (ChrAVE) trainer embedded into a helicopter for use in maintaining certain perishable skills. Specifically this thesis will address the task of helicopter low-level land navigation. The ChrAVE was developed to substantiate the viability of having embedded trainers in helicopters. The ChrAVE is comprised of commercial off the shelf (COTS) equipment on a transportable cart. In determining whether a system such as the ChrAVE is viable as a laboratory for continued training in virtual environment, the opinion of actual pilots that were tasked with realistic workloads was used. Additionally, empirical data was collected and evaluated according to the subject pool’s thresholds for acceptable low-level navigation performance.

1992

The value of rotorcrafl simulators in providing increased safety, reduced operating/training cost, and enhanced mission training has been well documented in the past 20 years. Because of the increased emphasis on rotorcraft simulation, the FAA has launched a program to establish certification standards for rotorcrafl simulators. This program is aimed at updating both rotorcraft simulator standards and the methods of simulator validation through objective and subjective tests. No methodological and acceptance criteria currently exist for the performance and handling-qualities assessment of rotorcrafl simulators. In order to establish certification criteria, a planned research effort to quantify the system capabilities of "selective fidelity" simulators is required. This paper addresses the initial step toward that goal: the establishment of a method for defining the performance and

Modeling and Simulation Technologies Conference and Exhibit, 1999

The authors conducted further research with cueing algorithms for control of flight simulator motion systems. A variation of the so-called optimal algorithm was formulated using simulated aircraft angular velocity input as a basis. Models of the human vestibular sensation system, i.e. the semicircular canals and otoliths, are incorporated within the algorithm. Comparisons of angular velocity cueing responses showed a significant improvement over a formulation using angular acceleration input. Results also compared favorably with the coordinated adaptive washout algorithm, yielding similar results for angular velocity cues while eliminating false cues and reducing the tilt rate for longitudinal cues. These results were confirmed in piloted tests on the current motion system at NASA-Langley, the Visual Motion Simulator (VMS). Proposed future developments by the authors in cueing algorithms are revealed. The new motion system, the Cockpit Motion Facility (CMF), where the final evaluation of the cueing algorithms will be conducted, is also described.

The Aeronautical Journal, 2005

An advanced design process applicable to the specification of flight simulator cueing systems is presented in this paper. This process is based on the analysis of the pilot-vehicle control loop by using a pilot model incorporating both visual and vestibular feedback, and the aircraft dynamics. After substituting the model for the simulated aircraft, the analysis tools are used to adjust the washout filter parameters with the goal of restoring pilot control behaviour. This process allows the specification of the motion cueing algorithm. Then, based on flight files representative of the operational flight envelope, the required motion system space is determined. The motion-base geometry is established based on practical limitations, as well as criteria for the stability of the platform with respect to singular conditions. With this process the characteristics of the aircraft, the tasks to be simulated, and the missions themselves are taken into account in defining the simulator motion...

2019

Copyright © 2019 by the Vertical Flight Society. All rights reserved. This paper examines the trends in rotorcraft accident statistics, particularly regarding Loss of Control In-flight accidents (LOC-I), with the aim of stimulating interest in new research relevant to this area. Despite recent safety initiatives, LOC-I rotorcraft accidents have been identified as a significant and growing contribution to accident rates. The fixed-wing commercial airline community faced a similar situation starting in the late 1990s and, through a coordinated international effort, developed a new training program to help reduce accident rates. Lessons learned from the fixed-wing work are presented to highlight the need for improved rotorcraft modeling tools to reduce rotorcraft accidents through higher-quality, simulator-based training programs. The findings from previous and ongoing rotorcraft modeling and simulation research are presented, and areas for further research are identified. A proposal i...