Novel Approach to Rotorcraft Simulation Fidelity Enhancement and Assessment
Lead Research Organisation:
University of Liverpool
Department Name: Mechanical and Aerospace
Abstract
The vision for this research is to develop a novel toolset for flight simulation fidelity enhancement. This represents a step-change in simulator qualification, is well-timed making a significant contribution to the UoL initiated NATO STO AVT-296-RTG activity and will have an immediate impact through engagement with Industry partners.
High fidelity modelling and simulation are prerequisites for ensuring confidence in decision making during aircraft design and development, including performance and handling qualities estimation, control law development, aircraft dynamic loads analysis, and the creation of a realistic piloted simulation environment. The ability to evaluate/optimise concepts with high confidence and stimulate realistic pilot behaviour are the kernels of quality flight simulation, in which pilots can train to operate aircraft proficiently and safely and industry can design with lower risk.
Regulatory standards such as CS-FSTD(H) and FAA AC120-63 describe the certification criteria and procedures for rotorcraft flight training simulators. These documents detail the component fidelity required to achieve "fitness for purpose", with criteria based on "tolerances", defined as acceptable differences between simulation and flight, typically +/- 10% for the flight model. However, these have not been updated for several decades, while on the military side, the related practices in NATO nations are not harmonised and have often been developed for specific applications. Methods to update the models for improved fidelity are mostly ad-hoc and, without a strong scientific foundation, are often not physics-based.
This research will provide a framework for such harmonisation removing the barriers to adopting physics-based flight modelling and will create new, more informed, standards. In this research two aspects of fidelity will be tackled, predictive fidelity (the metrics and tolerances in the standards) and perceptual fidelity (pilot opinion). The predictive fidelity aspect of the research will use System Identification techniques to provide a systematic framework for 'enhancing' a physics-based simulation model. The perceptual fidelity research will develop a rational, novel process for task-specific motion tuning together with a robust methodology for capturing pilots' subjective assessment of the overall fidelity of a simulator. Extensive use will be made of flight simulation and real-world flight tests throughout this project in both the predictive and perceptual fidelity research.
High fidelity modelling and simulation are prerequisites for ensuring confidence in decision making during aircraft design and development, including performance and handling qualities estimation, control law development, aircraft dynamic loads analysis, and the creation of a realistic piloted simulation environment. The ability to evaluate/optimise concepts with high confidence and stimulate realistic pilot behaviour are the kernels of quality flight simulation, in which pilots can train to operate aircraft proficiently and safely and industry can design with lower risk.
Regulatory standards such as CS-FSTD(H) and FAA AC120-63 describe the certification criteria and procedures for rotorcraft flight training simulators. These documents detail the component fidelity required to achieve "fitness for purpose", with criteria based on "tolerances", defined as acceptable differences between simulation and flight, typically +/- 10% for the flight model. However, these have not been updated for several decades, while on the military side, the related practices in NATO nations are not harmonised and have often been developed for specific applications. Methods to update the models for improved fidelity are mostly ad-hoc and, without a strong scientific foundation, are often not physics-based.
This research will provide a framework for such harmonisation removing the barriers to adopting physics-based flight modelling and will create new, more informed, standards. In this research two aspects of fidelity will be tackled, predictive fidelity (the metrics and tolerances in the standards) and perceptual fidelity (pilot opinion). The predictive fidelity aspect of the research will use System Identification techniques to provide a systematic framework for 'enhancing' a physics-based simulation model. The perceptual fidelity research will develop a rational, novel process for task-specific motion tuning together with a robust methodology for capturing pilots' subjective assessment of the overall fidelity of a simulator. Extensive use will be made of flight simulation and real-world flight tests throughout this project in both the predictive and perceptual fidelity research.
Planned Impact
There will be many beneficiaries from this work including Universities, the simulation industry and research institutes.
In terms of the rotorcraft simulation industry, an immediate impact will be made via one of the project partners, Advanced Rotorcraft Technology (ART) who will use the outputs from the research to upgrade their FLIGHTLAB software. Other beneficiaries will be the wider rotorcraft simulation industry who will improve the quality and competitiveness of their products, through engagement with regular webinars and workshops. The outputs of the research will provide a stronger scientific basis for fidelity. It will also enable the adoption of improved certification metrics and tests in new standards. This pathway will lead to deeper industry and regulator understanding and the subsequent adoption of the proposed processes and practices in their operations. The methodology developed in the will provide the basis for model enhancement and informing future defence requirements for training devices and their certification, feeding into future aircraft clearance activities.
A problem-based-learning (PBL) workshop will be developed and held at the University of Liverpool. The workshop will involve rotorcraft simulation model development and validation, real time simulation and fidelity assessment by test pilots and will attract significant interest from the rotorcraft and flight simulator industries, together with test pilot/engineer schools and civil and military regulatory authorities and academia e.g. UK's Vertical Lift Network (VLN). The material from this activity will form the basis of a workshop that can be delivered at international conferences e.g. European Rotorcraft Fora (ERF) to ensure the knowledge and understanding gained from the project are made available to the broader rotorcraft community. Further dissemination of the research outputs will occur through conference (e.g. American Helicopter Society (AHS) Forum, ERF) and journal publications (e.g. Aeronautical Journal, Progress in Aerospace Sciences).
Academia will benefit from the research at both the collaborating Universities and at other institutions. The PBL workshop will be open to academia and the project will make accessible a large amount of flight and simulation data to other institutions for their own research needs, leading to new research opportunities. Outputs from the proposed research will be woven into the curricula and module specifications at both the institutes collaborating in the project.
The proposed research will contribute to the NATO STO AVT-296-RTG activity, "Rotorcraft Flight Simulation Model Fidelity Improvement and Assessment", (2018-20) and the follow-on research lecture series. The research lecture series, to be given in three NATO nations, is another key pathway to impact, delivering knowledge and best practices to industry, government and academia.
Schools will also be potential beneficiaries of the research as a programme of visits to school and school visits to the simulator will be developed showcasing the research.
In terms of the rotorcraft simulation industry, an immediate impact will be made via one of the project partners, Advanced Rotorcraft Technology (ART) who will use the outputs from the research to upgrade their FLIGHTLAB software. Other beneficiaries will be the wider rotorcraft simulation industry who will improve the quality and competitiveness of their products, through engagement with regular webinars and workshops. The outputs of the research will provide a stronger scientific basis for fidelity. It will also enable the adoption of improved certification metrics and tests in new standards. This pathway will lead to deeper industry and regulator understanding and the subsequent adoption of the proposed processes and practices in their operations. The methodology developed in the will provide the basis for model enhancement and informing future defence requirements for training devices and their certification, feeding into future aircraft clearance activities.
A problem-based-learning (PBL) workshop will be developed and held at the University of Liverpool. The workshop will involve rotorcraft simulation model development and validation, real time simulation and fidelity assessment by test pilots and will attract significant interest from the rotorcraft and flight simulator industries, together with test pilot/engineer schools and civil and military regulatory authorities and academia e.g. UK's Vertical Lift Network (VLN). The material from this activity will form the basis of a workshop that can be delivered at international conferences e.g. European Rotorcraft Fora (ERF) to ensure the knowledge and understanding gained from the project are made available to the broader rotorcraft community. Further dissemination of the research outputs will occur through conference (e.g. American Helicopter Society (AHS) Forum, ERF) and journal publications (e.g. Aeronautical Journal, Progress in Aerospace Sciences).
Academia will benefit from the research at both the collaborating Universities and at other institutions. The PBL workshop will be open to academia and the project will make accessible a large amount of flight and simulation data to other institutions for their own research needs, leading to new research opportunities. Outputs from the proposed research will be woven into the curricula and module specifications at both the institutes collaborating in the project.
The proposed research will contribute to the NATO STO AVT-296-RTG activity, "Rotorcraft Flight Simulation Model Fidelity Improvement and Assessment", (2018-20) and the follow-on research lecture series. The research lecture series, to be given in three NATO nations, is another key pathway to impact, delivering knowledge and best practices to industry, government and academia.
Schools will also be potential beneficiaries of the research as a programme of visits to school and school visits to the simulator will be developed showcasing the research.
Organisations
- University of Liverpool (Lead Research Organisation)
- Georgia Institute of Technology (Collaboration)
- Advanced Rotorcraft Technology Inc (Collaboration)
- Thales Group (Collaboration)
- German Aerospace Centre (DLR) (Collaboration)
- Penn State University (Collaboration)
- National Office for Aerospace Studies and Research (Collaboration)
- Lockheed Martin (United States) (Collaboration)
- Leonardo S.p.A. (Collaboration)
- CAE Inc (Collaboration)
- NRC Canada (Collaboration)
- Boeing (Collaboration)
- German Aerospace Center (Project Partner)
- National Research Council Canada (Project Partner)
People |
ORCID iD |
Mark White (Principal Investigator) | |
G D Padfield (Co-Investigator) |
Publications
Agarwal D.
(2019)
Rotorcraft simulation fidelity for low speed manoeuvring using 'additive' system identification
in 45th European Rotorcraft Forum 2019, ERF 2019
Taghizad A.
(2021)
Simulation model fidelity enhancement using corrective force and moment increments: Review of activity performed in NATO-AVT Panel 296
in 77th Annual Vertical Flight Society Forum and Technology Display, FORUM 2021: The Future of Vertical Flight
Pavel M.D.
(2021)
Simulation fidelity assessment for rotorcraft - Methods and metrics: Sketches from the work of NATO AVT-296
in 77th Annual Vertical Flight Society Forum and Technology Display, FORUM 2021: The Future of Vertical Flight
Roscoe J.
(2022)
Rotorcraft Pitch-Surge Motion Cueing Requirements for a Simulated Offshore Approach Task
in 78th Vertical Flight Society Annual Forum and Technology Display, FORUM 2022
Cameron N.
(2021)
Appraisal of handling qualities standards for rotorcraft lateral-directional dynamics
in AIAA Scitech 2021 Forum
White M
(2021)
Review of flight simulation fidelity requirements to help reduce 'rotorcraft loss of control in-flight' accident rates
in CEAS Aeronautical Journal
Agarwal D
(2021)
Rotorcraft Lateral-Directional Oscillations: The Anatomy of a Nuisance Mode
in Journal of the American Helicopter Society
Lu L
(2023)
A New Heuristic Approach to Rotorcraft System Identification
in Journal of the American Helicopter Society
Memon W
(2021)
Helicopter Handling Qualities: A study in pilot control compensation
in The Aeronautical Journal
Agarwal D
(2022)
The use of augmented rotor inflow to predict rotorcraft responses in hover and low-speed manoeuvres
in The Aeronautical Journal
Description | The research developed new methodoliges for updating flight simualtion models using a pyhsics based approach. A large database of real-world flight test and flight simulator data is now avaialble for the rotorcraft research community to use in future research. The project contributed to a NATO activity on flight simulation model fidelity assessment and improvements using seven case stuies for rotorcraft from the scale of UAVs to large transport helictopters. Together with 2 international lectures for industry, academia and research laboratories, this material will serve as a valuable reference source for flight simulation practitioners. |
Exploitation Route | Reference material in the form of a NATO final report, recorded presentations and conference and journal papers have been produced which are available to the international community for their future research and development needs. |
Sectors | Aerospace Defence and Marine Government Democracy and Justice Transport |
Description | The work was used as part of a new lecture series aimed at up-skilling rotorcraft modelling and simulation practitioners. |
First Year Of Impact | 2021 |
Sector | Aerospace, Defence and Marine |
Impact Types | Policy & public services |
Description | NATO AVT-296 |
Organisation | Advanced Rotorcraft Technology Inc |
Country | United States |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Boeing |
Country | United States |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | CAE Inc |
Country | Canada |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Georgia Institute of Technology |
Country | United States |
Sector | Academic/University |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | German Aerospace Centre (DLR) |
Department | DLR Braunschweig |
Country | Germany |
Sector | Public |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Leonardo S.p.A. |
Country | Italy |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Lockheed Martin |
Country | United States |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | NRC Canada |
Country | Canada |
Sector | Public |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | National Office for Aerospace Studies and Research |
Department | ONERA Salon-de-Provence Center |
Country | France |
Sector | Public |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Penn State University |
Country | United States |
Sector | Academic/University |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | NATO AVT-296 |
Organisation | Thales Group |
Country | France |
Sector | Private |
PI Contribution | I am the Vice Chair of this NATO activity. My team is providing flight simulation models to the activity and also new numerical techniques for assessing flight simulation mode fidelity. |
Collaborator Contribution | The partner are providing access to flight test data and numerical methods in support of this activity. |
Impact | The AVT is working on a final report and also a training activity that will follw the collaboration. Conference papers are currently under preparation. |
Start Year | 2018 |
Description | Support for Flight Testing |
Organisation | NRC Canada |
Country | Canada |
Sector | Public |
PI Contribution | The Liverpool team have been working with the NRC to validate the existing flight simulation models. |
Collaborator Contribution | The Flight Research Laboratory have undertaken a number of ground based measurements and rotor tests to help validate information in Liverpool's flight simulation model. They have also started to gather flight test data in support of the research and continue to provide technical support. |
Impact | A paper has been accepted for the 75th Vertical Flight Society Forum which will be submitted in March for presentation in May 2019. |
Start Year | 2018 |
Description | NATO AVT-296 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | Rotorcraft flight dynamics simulation models require high levels of fidelity to be suitable as prime items in support of life cycle practises, particularly vehicle and control design and development, and system and trainer certification. On the civil side, both the FAA (US) and EASA (Europe) have documented criteria (metrics and practises) for assessing model and simulator fidelity as compared to flight-test data although these have not been updated for several decades. Methods to update the models for improved fidelity are mostly ad-hoc and lack a rational and methodical approach. Modern rotorcraft system identification (SID) and inverse simulation methods have been developed in recent years that provide new approaches well suited to pilot-in-the-loop fidelity assessment and systematic techniques for updating simulation models to achieve the needed level of fidelity. To coordinate efforts and improve the knowledge in this area, STO Applied Vehicle Technology Panel Research Task Group (STO AVT-296 RTG) was constituted to evaluate update methods used by member nations to find best practises and suitability for different applications including advanced rotorcraft configurations |
Year(s) Of Engagement Activity | 2018,2019,2020,2021 |
Description | Rotorcraft Flight Simulation Model Fidelity Improvement and Assessment - Lecture Series |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | The AVT-365 Research Lecture Series (RLS) disseminated the AVT-296's achievements and provided the new knowledge available to the beneficiaries within NATO, to include over 250 operators, government and research institutions and industry |
Year(s) Of Engagement Activity | 2021 |
Description | Rotorcraft Simulation Fidelity (RSF) Workshop on the Simulation Fidelity Rating (SFR) Scale |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | The RSF project has been making in-roads to further examine, understand and quantify pilot control compensation [1] and, by extension, pilot control adaptation. There is significant interest in this topic in the helicopter community e.g., VFS papers, RoCS and RSF projects [2-6]. In the Lifting Standards project , in addition to the development of 'preliminary' pilot control adaptation metrics [7], the Simulation Fidelity Rating (SFR) scale was produced [8], together with an initial user guide [9]. The development of an updated SFR user guide is the focus of a workshop planned to be held in-person at UoL (and online for attendees unable to travel), engaging organisations who have previously and are currently contributing to the RSF/RoCS projects. The objectives (O) of the workshop are: 1. To inform the development of an updated SFR user guide for distribution to the user community for comment 2. To review the development and application of the SFR scale and obtain participant feedback on the process and its usage 3. To define the semantics used in the SFR scale 4. To review and recommend objective metrics for comparative performance and task strategy adaptation 5. To identify case studies for use in the SFR guidance material 6. To identify the user community across rotorcraft training, pre-certification design and development, certification and regulation 7. To identify opportunities for inclusion of the SFR in emerging modelling and simulation standards The workshop closed with a round table discussion to highlight the key themes that emerged and to capture the actions. The main themes were: 1. There needs to be clear definitions of words such as "equivalent" and "similar" and examples provided of their use. 2. A clear definition, and examples, of "compensation" needs to be provided. 3. Case studies for a range of SFR applications needs to be included in the guidance material. 4. Any fidelity assessments should conducted by people trained in the use of the SFR scale. The assessment should be conducted by a team of at least two proficient in the use of the scale and requires a clear definition of the task and the related performance measures. |
Year(s) Of Engagement Activity | 2022 |