Adverse rotorcraft pilot couplings¿Past, present and future challenges

Abstract Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and suppressing these inadvertent and sustained aircraft oscillations, known as aircraft (rotorcraft)-pilot couplings (A/RPCs) is a challenging problem for the designers. The goal of the present paper is to give an overview on the state-of-the-art in RPC problem, underlining the future challenges in this field. It is shown that, exactly as in the case of fixed wing APCs, RPCs existed from the beginning of rotorcraft development and that the problem of eliminating them is not yet solved: the current rotorcraft modelling for RPC analysis is rather limited to the particular case analysed and there is a lack of quantitative pilot behavioural models to analyse RPCs. The paper underlines the importance of involuntary pilot control actions, generally attributed to biodynamic couplings in predicting RPCs in rotorcraft. It is also shown that recent experiences demonstrate that modern rotorcraft seem to embed tendencies predisposing the flight control system FCS system towards dangerous RPCs. As the level of automation is likely to increase in future designs, extending to smaller aircraft and to different kinds of operation, the consequences of the pilot ‘fighting’ the FCS system and inducing A/RPCs needs to be eradicated. In Europe, the ARISTOTEL project (2010–2013) has been launched with the aim of understanding and predicting modern aircraft's susceptibility to A/RPC. The present paper gives an overview of future challenges to be solved for RPC-free design and some new solutions herein.

[1]  Ralph H Smith,et al.  A Theory for Longitudinal Short-Period Pilot Induced Oscillations. , 1977 .

[2]  Gareth D. Padfield,et al.  The birth of flight control: An engineering analysis of the Wright brothers’ 1902 glider , 2003, The Aeronautical Journal (1968).

[3]  Mario Hamers,et al.  Increasing Handling Qualities and Flight Control Performance using an Air Resonance Controller , 2008 .

[4]  Ch. Kessler,et al.  Active rotor control for helicopters: individual blade control and swashplateless rotor designs , 2011 .

[5]  G. Reichert,et al.  Helicopter vibration control: a survey , 1980 .

[6]  R. E. Smith,et al.  An in-flight investigation of pilot-induced oscillation suppression filters during the fighter approach and landing task , 1982 .

[7]  Giuseppe Quaranta,et al.  Adverse rotorcraft-pilot coupling: The construction of the test campaigns at the University of Liverpool , 2008 .

[8]  Kevin,et al.  A Method to Determine Maximum Flight Control Authority Through Hardover Failure Testing , 2009 .

[9]  Rogers E Smith.  Effects of Control System Dynamics on Fighter Approach and Landing Longitudinal Flying Qualities. (Volume I). , 1978 .

[10]  Ronald A. Hess,et al.  Unified Theory for Aircraft Handl!ng Qualities and Adverse Aircraft-Pilot Coupling , 2022 .

[11]  A. Tustin,et al.  The nature of the operator's response in manual control, and its implications for controller design , 1947 .

[12]  Peter M. T. Zaal,et al.  Estimation of Time-Varying Pilot Model Parameters , 2011 .

[13]  Andrea Zanoni,et al.  Rotorcraft Pilot Impedance From Inverse Dynamics-Based Biomechanical Model , 2012 .

[14]  Walden,et al.  A Retrospective Survey of Pilot-Structural Coupling Instabilities in Naval Rotorcraft , 2007 .

[15]  David G. Mitchell,et al.  Development of Methods and Devices to Predict and Prevent Pilot-Induced Oscillations (CD-ROM) , 2000 .

[16]  G. Ferreres,et al.  Nonlinear analysis in the presence of parametric uncertainties , 1998 .

[17]  Wim de Boer,et al.  Flight Control Design - Best Practices , 2000 .

[18]  W. A. Kuczynski,et al.  The Influence of Engine/Fuel Control Design on Helicopter Dynamics and Handling Qualities , 1979 .

[19]  Joost Venrooij,et al.  Biodynamic feedthrough is task dependent , 2010, 2010 IEEE International Conference on Systems, Man and Cybernetics.

[20]  John Vorwald,et al.  Dynamics Workshop On Rotor Vibratory Loads Prediction , 1998 .

[21]  G. Iooss,et al.  Elementary stability and bifurcation theory , 1980 .

[22]  R. Fortenbaugh,et al.  Advanced Flight Control Development for Single-Pilot Attack Helicopters , 1986 .

[23]  G. Höhne.  Roll Ratcheting: Cause and Analysis , 2001 .

[24]  Duane T. McRuer,et al.  Analysis of nonlinear control systems , 1962 .

[25]  Roger Douglas Connor.  Wrecked Rotors: Understanding Rotorcraft Accidents, 1935-1945 , 2010 .

[26]  Michael Jump,et al.  Investigation of the Flare Maneuver Using Optical Tau , 2006 .

[27]  Mark B. Tischler,et al.  Assessment of Digital Flight-Control Technology for Advanced Combat Rotorcraft , 1989 .

[28]  David N. Lee,et al.  Sensory and intrinsic coordination of movement , 1999, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[29]  Jorge Tierno,et al.  Describing Function Analysis in the Presence of Uncertainty , 1997 .

[30]  C. J. Ockier.  Pilot Induced Oscillations in Helicopters - Three Case Studies. , 1996 .

[31]  George E. Cooper,et al.  The use of pilot rating in the evaluation of aircraft handling qualities , 1969 .

[32]  Ronald A. Hess.  A Preliminary Study of Human Pilot Dynamics in the Control of Time-Varying Systems , 2011 .

[33]  Ina Niewind,et al.  Investigations on boundary avoidance tracking and pilot inceptor workload , 2011 .

[34]  Daan M. Pool,et al.  Objective Evaluation of Flight Simulator Motion Cueing Fidelity Through a Cybernetic Approach , 2012 .

[35]  Victor Rodchenko,et al.  Handling Qualities Criteria for Roll Control of Highly Augmented Aircraft , 2003 .

[36]  Gareth D. Padfield,et al.  Helicopter Flight Dynamics , 2000 .

[37]  Ralph H Smith,et al.  Handling Quality Requirements for Advanced Aircraft Design: Longitudinal Mode , 1979 .

[38]  Maurice I. Young,et al.  A Theory of Rotor Blade Motion Stability in Powered Flight , 1964 .

[39]  Linghai Lu,et al.  Tau guidance in boundary-avoidance tracking: new perspectives on pilot-induced oscillations , 2012 .

[40]  Ezra S. Krendel,et al.  Mathematical Models of Human Pilot Behavior , 1974 .

[41]  A. Rantzer,et al.  System Analysis via Integral Quadratic Constraints. Part II , 1997 .

[42]  G. Sell,et al.  The Hopf Bifurcation and Its Applications , 1976 .

[43]  Brian Stadler,et al.  Simulation investigation of Category I and II PIO , 1999 .

[44]  Gary Clark,et al.  How long do pilots look forward? Prospective visual guidance in terrain hugging flight , 2007 .

[45]  Gareth D. Padfield,et al.  Handling qualities degradation in tilt-rotor aircraft following flight control system failures , 2004 .

[46]  David G. Mitchell.  Identifying the Pilot in Pilot-Induced Oscillations , 2000 .

[47]  Brack,et al.  The Arrival of the Tiltrotor , 2005 .

[48]  W. Johnson,et al.  Nonlinear Behavior of an Elastomeric Lag Damper Undergoing Dual-Frequency Motion and its Effect on Rotor Dynamics , 1987 .

[49]  Randy D. Warren,et al.  An Investigation of the Effects of Boundary Avoidance on Pilot Tracking , 2012 .

[50]  Anubhav Datta,et al.  Validation and Understanding of UH-60A Vibratory Loads in Steady Level Flight , 2002 .

[51]  David G. Mitchell,et al.  A PIO Case Study - Lessons Learned Through Analysis , 2005 .

[52]  James Planeaux,et al.  Bifurcation analysis of a model fighter aircraft with control augmentation , 1990 .

[53]  Joost Venrooij,et al.  Robust Stability Analysis: a Tool to Assess the Impact of Biodynamic Feedthrough on Rotorcraft , 2012 .

[54]  Gareth D. Padfield,et al.  The making of helicopter flying qualities: a requirements perspective , 1998, The Aeronautical Journal (1968).

[55]  Marion A. Eppler,et al.  Development of Visually Guided Locomotion , 1998 .

[56]  Ronald A. Hess.  A unified theory for aircraft handling qualities and adverse aircraft-pilot coupling , 1997 .

[57]  Pavel,et al.  Capturing the switch between point tracking and boundary avoiding pilot behaviour in a PIO event , 2008 .

[58]  A. Rantzer,et al.  System analysis via integral quadratic constraints , 1997, IEEE Trans. Autom. Control..

[59]  Giuseppe Quaranta,et al.  Experimental and numerical helicopter pilot characterization for aeroelastic rotorcraft–pilot coupling analysis , 2013 .

[60]  Graham H. Watson,et al.  Multiresolution analysis using adaptive wavelets , 1994, Defense, Security, and Sensing.

[61]  D. L. Key,et al.  Assessment of simulation fidelity using measurements of piloting technique in flight , 1984 .

[62]  Moshe Idan,et al.  EFFECTS OF BIODYNAMIC COUPLING ON THE HUMAN OPERATOR MODEL , 1990 .

[63]  Massimo Gennaretti,et al.  Adverse rotorcraft-pilot coupling: Recent research activities in Europe , 2008 .

[64]  John Hodgkinson,et al.  Aircraft Handling Qualities , 1999 .

[65]  K H Hohenemser.  Hingeless Rotorcraft Flight Dynamics , 1974 .

[66]  James B. Dryfoos,et al.  An Approach to Reducing Rotor-Body Coupled Roll Oscillations on the RAH-66 Comanche Using Modified Roll Rate Feedback , 1999 .

[67]  John W. Smith,et al.  Biomechanically Induced and Controller Coupled Oscillations Experienced on the F-16XL Aircraft During Rolling Maneuvers , 1996 .

[68]  Michael Jones,et al.  Tau Coupling Investigation Using Positive Wavelet Analysis , 2013 .

[69]  Ezra S. Krendel,et al.  The human operator as a servo system element , 1959 .

[70]  Michael Jump,et al.  Adverse Rotorcraft-Pilot Couplings - Prediction and Suppression of Rigid Body RPC , 2008 .

[71]  Eileen A Bjorkman.  Flight test evaluation of techniques to predict longitudinal pilot induced oscillations , 1986 .

[72]  Peter Eberhard,et al.  The Second Joint International Conference on Multibody System Dynamics – IMSD 2012 – Was Held May 29 to June 1, 2012 at the University of Stuttgart, Germany , 2013 .

[73]  Duane T. McRuer,et al.  Analysis of nonlinear control systems , 1962 .

[74]  Gregory J. Wilson,et al.  Test Approaches To External Sling Load Instabilities , 1968 .

[75]  Mark B. Tischler,et al.  Applications of flight control system methods to an advanced combat rotorcraft , 1989 .

[76]  Gareth D. Padfield.  Rotorcraft Handling Qualities Engineering: Managing the Tension between Safety and Performance 32nd Alexander A. Nikolsky Honorary Lecture , 2013 .

[77]  Ronald A. Hess,et al.  Study of Helicopter Roll Control Effectiveness Criteria. , 1986 .

[78]  Ryan D. Blake,et al.  Boundary Avoidance Tracking: Consequences (and Uses) of Imposed Boundaries on Pilot-Aircraft Performance , 2009 .

[79]  S. Mallat.  A wavelet tour of signal processing , 1998 .

[80]  Mohammad M. Lone,et al.  Review of pilot modelling techniques , 2010 .

[81]  David G. Mitchell,et al.  Identifying a PIO Signature - New Techniques Applied to an Old Problem , 2006 .

[82]  Gareth D. Padfield,et al.  How do helicopter pilots know when to stop, turn or pull up? , 2001 .

[83]  Stphane Mallat,et al.  A Wavelet Tour of Signal Processing, Third Edition: The Sparse Way , 2008 .

[84]  Giuseppe Quaranta,et al.  Coupled Bioaeroservoelastic Rotorcraft-Pilot Simulation , 2013 .

[85]  Gloria K. Yamauchi,et al.  A Status of NASA Rotorcraft Research , 2009 .

[86]  David G. Mitchell,et al.  Evolution, Revolution, and Challenges of Handling Qualities , 2004 .

[87]  Kenneth H. Landis,et al.  Handling Qualities Evaluation of the ADOCS Primary Flight Control System , 1986 .

[88]  John C. Doyle.  Analysis of Feedback Systems with Structured Uncertainty , 1982 .

[89]  Holger Duda.  Effects of Rate Limiting Elements in Flight Control Systems - A New PIO-Criterion. , 1995 .

[90]  Duane T. McRuer,et al.  Pilot-Induced Oscillations and Human Dynamic Behavior , 1995 .

[91]  G. Padfield,et al.  Optical Tau in Boundary Avoidance Tracking - A New Perspective on Pilot Induced Oscillations , 2010 .

[92]  John J. Rieser,et al.  Action as an organizer of learning and development , 2005 .

[93]  Ingrid Daubechies,et al.  Ten Lectures on Wavelets , 1992 .

[94]  Donald A. Johnson.  Suppression of Pilot-Induced Oscillation (PIO) , 2002 .

[95]  Giuseppe Quaranta,et al.  An Investigation of Aeroelastic Rotorcraft-Pilot Interaction , 2011 .

[96]  W. S. Hindson,et al.  Influence of high-order dynamics on helicopter flight-control system bandwidth , 1986 .

[97]  David G. Mitchell,et al.  Development of Handling Qualities Criteria for Rotorcraft with Externally Slung Loads , 2006 .

[98]  Massimo Gennaretti,et al.  A finite-state aeroelastic model for rotorcraft pilot-assisted-oscillations analysis , 2012 .

[99]  Duane T. McRuer,et al.  A Review of Quasi-Linear Pilot Models , 1967 .

[100]  Robert M. Taylor,et al.  From Safety Net to Augmented Cognition: Using Flexible Autonomy Levels for On-Line Cognitive Assistance and Automation , 2003 .

[101]  McDonnell Douglas Helicopter Systems,et al.  Longbow Apache Flight Control System Development and Flight Test , 1996 .

[102]  M. D. Pavel,et al.  New Insights Into Pilot Behaviour During Hazardous Rotorcraft Pilot Induced Oscillations , 2006 .

[103]  Richard W. Pew,et al.  More Than 50 Years of History and Accomplishments in Human Performance Model Development , 2008, Hum. Factors.

[104]  David G. Mitchell,et al.  Proposed Incorporation of Mission-Oriented Flying Qualities into MIL-STD-1797A. , 1994 .

[105]  Graham H. Watson,et al.  Positive Wavelet Representation of Fractal Signals and Images , 1993 .

[106]  David G. Mitchell,et al.  Recommended Practices for Exposing Pilot-Induced Oscillations or Tendencies in the Development Process , 2004 .

[107]  Mark B. Tischler,et al.  System Identification Requirements for High-Bandwidth Rotorcraft Flight Control System Design , 1990, 1991 American Control Conference.

[108]  William G. Bousman,et al.  High Load Conditions Measured on a UH-60A in Maneuvering Flight , 1998 .

[109]  Robert G. Loewy,et al.  Helicopter Vibrations: A Technological Perspective , 1984 .

[110]  Matthias Heller,et al.  Enhancement of the Nonlinear OLOP-PIO-Criterion Regarding Phase-Compensated Rate Limiters , 2008 .

[111]  R. E. Magdaleno,et al.  Experimental validation and analytical elaboration for models of the pilot's neuromuscular subsystem in tracking tasks , 1971 .

[112]  Duane T. McRuer,et al.  AVIATION SAFETY AND PILOT CONTROL: UNDERSTANDING AND PREVENTING UNFAVORABLE PILOT-VEHICLE INTERACTIONS , 1997 .

[113]  Randall E. Bailey,et al.  A quantitative criterion for pilot-induced oscillations - Time domain Neal-Smith criterion , 1996 .

[114]  P. Fabre,et al.  Probabilistic neural detector of pilot induced oscillations (PIO) , 2001 .

[115]  Michael Jump,et al.  Prediction of Rotorcraft Pilot-Induced Oscillations Using the Phase-Aggression Criterion , 2013 .

[116]  David G. Mitchell,et al.  A critical examination of PIO prediction criteria , 1998 .

[117]  H. C. Curtiss,et al.  Rotorcraft Stability and Control: Past, Present, and Future – The 20th Annual Alexander A. Nikolsky Lecture , 2003 .

[118]  Ch. Kessler,et al.  Active rotor control for helicopters: motivation and survey on higher harmonic control , 2011 .

[119]  B-dul Iuliu Maniu,et al.  Trigger event - a key factor in adverse Aircraft/Rotorcraft Pilot Couplings , 2012 .

[120]  P.M.T. Zaal.  Pilot Control Behavior Discrepancies Between Real and Simulated Flight Caused by Limited Motion Stimuli , 2011 .

[121]  R. E. Smith,et al.  PIO: A Historical Perspective , 1995 .

[122]  M. A. Diftler,et al.  Helicopter Simulation Development By Correlation With Frequency Sweep Flight Test Data , 1989 .

[123]  George E. Tucker,et al.  Flying quality analysis and flight evaluation of a highly augmented combat rotorcraft , 1991 .

[124]  Peter,et al.  Use of Wavelet Scalograms to Characterize Rotorcraft Pilot-Vehicle System Interactions , 2010 .

[125]  Hafid Smaili,et al.  Present and Future Trends in Rotorcraft Pilot Couplings (RPCs) - A Retrospective Survey of Recent Research Activities Within the European Project ARISTOTEL , 2011 .

[126]  Giuseppe Quaranta,et al.  Aeroservoelastic Analysis of Rotorcraft-Pilot Coupling: a Parametric Study , 2010 .

[127]  Mark B. Tischler,et al.  Digital Control of Highly Augmented Combat Rotorcraft. , 1987 .

[128]  Robin Lantzsch,et al.  Handling qualities studies into the interaction between active sidestick parameters and helicopter response types , 2013 .

[129]  Syed Firasat Ali.  A Low Cost Simulation System to Demonstrate Pilot Induced Oscillation Phenomenon , 1997 .

[130]  W H Levison.  Model for human controller performance in vibration environments. , 1978, Aviation, space, and environmental medicine.

[131]  Hafid Smaili,et al.  A Retrospective Survey of Adverse Rotorcraft Pilot Couplings in European Perspective , 2012 .

[132]  Rogers E. Smith,et al.  A Flying Qualities Criterion for the Design of Fighter Flight-Control Systems , 1971 .

[133]  Christian B Allen,et al.  48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition , 2010 .

[134]  David A. Hinton,et al.  The effects of display and autopilot functions on pilot workload for Single Pilot Instrument Flight Rule (SPIFR) operations , 1987 .

[135]  A. Tits,et al.  Robustness in the presence of mixed parametric uncertainty and unmodeled dynamics , 1991 .

[136]  Giuseppe Quaranta,et al.  Aeroelastic and Biodynamic Modelling for Stability Analysis of Rotorcraft-Pilot Coupling Phenomena , 2008 .

[137]  Jason D. Dotter.  An Analysis of Aircraft Handling Quality Data Obtained from Boundary Avoidance Tracking Flight Test Techniques , 2012 .

[138]  Michael Jones,et al.  Using the phase-aggression criterion to identify rotorcraft pilot coupling events , 2012 .

[139]  A. Halanay,et al.  Hopf bifurcations through delay in pilot reaction in a longitudinal flight , 2010 .

[140]  Alberto Cavallo,et al.  Robust flight control systems - A parameter space design , 1992 .

[141]  David G. Mitchell,et al.  Real-Time Detection of Pilot-Induced Oscillations , 2004 .

[142]  Jex Hr,et al.  Biomechanical models for vibration feedthrough to hands and head for a semisupine pilot. , 1978 .

[143]  Robert R. Bitmead.  Helicopter Vibration Control , 2002 .

[144]  William H. Levison,et al.  Biomechanical and Performance Response of Man in Six Different Directional Axis Vibration Environments , 1977 .

[145]  J. M. Bilger,et al.  Results of Structural Dynamic Testing of the XV-15 Tilt Rotor Research Aircraft , 1981 .

[146]  Juergen Kaletka,et al.  Frequency-Domain Identification of BO 105 Derivative Models with Rotor Degrees of Freedom. , 1991 .

[147]  D T McRuer,et al.  Small perturbation dynamics of the neuromuscular system in tracking tasks. NASA CR-1212. , 1968, NASA contractor report. NASA CR. United States. National Aeronautics and Space Administration.

[148]  Sikorsky Aircraft Division,et al.  Handling Qualities of the SH-60B Seahawk , 1981 .

[149]  Boeing Helicopters,et al.  Flying Qualities Evaluation of the V22 Tiltrotor , 1991 .

[150]  David G. Mitchell,et al.  The measurement and prediction of pilot-in-the-loop oscillations , 1994 .

[151]  Frans C. T. van der Helm,et al.  A practical biodynamic feedthrough model for helicopters , 2013 .

[152]  Raymond W. Prouty,et al.  Helicopter performance, stability, and control , 1986 .

[153]  Holger Duda.  Flight control system design considering rate saturation , 1998 .

[154]  D. Scheeres,et al.  New Solar Radiation Pressure Force Model for Navigation , 2010 .

[155]  Gareth D. Padfield,et al.  Handling-Qualities Analysis of the Wright Brothers' 1902 Glider , 2003 .

[156]  N. Goto,et al.  H/sub /spl infin//-model of the human pilot controlling unstable aircraft , 1995, 1995 IEEE International Conference on Systems, Man and Cybernetics. Intelligent Systems for the 21st Century.

[157]  William Gray,et al.  Boundary Avoidance Tracking: A New Pilot Tracking Model , 2005 .

[158]  Dennis P. McGuire,et al.  Fluidlastic Dampers and Isolators for Vibration Control in Helicopters , 1994 .

[159]  H. Jex,et al.  Manual Control Performance and Dynamic Response during Sinusoidal Vibration , 1973 .

[160]  P. G. Hamel.  Rotorcraft-Pilot Coupling. A Critical Issue for Highly Augmented Helicopters? , 1996 .

[161]  H. Duda.  Prediction of Pilot-in-the-Loop Oscillations Due to Rate Saturation , 1997 .

[162]  J. G. Jones,et al.  Analysis of atmospheric turbulence measurements by spectral and discretegust methods , 1989, The Aeronautical Journal (1968).

[163]  Chris L. Blanken,et al.  Investigation of the effects of bandwidth and time delay on helicopter roll-axis handling qualities , 1994 .

[164]  Gareth D. Padfield,et al.  Understanding the peculiarities of rotorcraft, pilot, couplings , 2008 .

[165]  Jean-Marc Biannic,et al.  Robustness analysis of flexible structures: practical algorithms , 2003 .

[166]  J. I. Elkind.  A SURVEY OF THE DEVELOPMENT OF MODELS FOR THE HUMAN CONTROLLER , 1964 .

[167]  Gareth D. Padfield.  Rotorcraft Handling Qualities Engineering Managing Tension between Safety and Performance , 2012 .

[168]  Joost Venrooij,et al.  Measuring biodynamic feedthrough in helicopters , 2011 .