Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-06T10:13:46.062Z Has data issue: false hasContentIssue false

Experimental evaluation of multivariable rotor control schemes

Published online by Cambridge University Press:  04 July 2016

G. J. Mullen
Affiliation:
National Flying Laboratory CentreCollege of AeronauticsCranfield University, UK
P. R. Brinson
Affiliation:
GKN Westland HelicoptersYeovil, UK

Abstract

The performance and robustness of a classical multivariable controller and one H compensator are assessed on a model rotor rig. Both control schemes are subjected to sinusoidal and step input tests in the pitch and roll axes under a range of operating conditions and configurations. A brief description of the characteristics of the rotor mathematical model is provided, followed by a summary of the design assessment criteria. Following a description of the two control law design techniques, the performance of each controller is verified on the mathematical model prior to evaluation on the rotor rig. In absolute terms, there is a poor correlation between the simulated and experimental values of the design assessment criteria for both controllers. However, in relative terms, the H control law achieves higher levels of damping and lower cross-couplings than the classical scheme although the measured improvements are not as substantial as predicted. In experimental frequency response tests at increasing advance ratios and various rotorspeeds, the H scheme again consistently achieves the lowest levels of cross-coupling. In summary, the results show that although there are practical performance and robustness benefits to be gained by employing more complex control algorithms, model uncertainty will substantially reduce the predicted benefits.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 1999 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Walker, D. and Postlethwaite, I. Full authority active control system design for a high performance helicopter, 16th European Rotorcraft Forum, London, 1990.Google Scholar
2. Yue, A. and Postlethwaite, I. Improvement of helicopter handling qualities using H-infinity optimisation, IEE Proceedings Part D, 1990, 137, (3).Google Scholar
3. Takahashi, M.D. Rotor-state feedback in the design of flight control laws for a hovering helicopter, J Amer Heli Soc, 1994, 39, (1).Google Scholar
4. Francis, B.A. A Course in H-infinity Control Theory, Springer-Verlag, 1987.Google Scholar
5. Maciejowski, J.M. Multivariable Feedback Design, Addison-Wesley, 1989.Google Scholar
6. Padfield, G.D. A theoretical model of helicopter flight mechanics for Memo 81048, 1981.Google Scholar
7. Brinson, P.R. Experimental Investigation of helicopter coupled rotor/body control, 17th European Rotorcraft Forum, Berlin, 1991.Google Scholar
8. Ellenrieder, T.J. Investigation of the Dynamic Wake of a Model Rotor, PhD thesis, Department of Aerospace Engineering, University of Bristol, 1996.Google Scholar
9. Mullen, G.J. Experimental Evaluation of the Performance and Robustness of Advanced Rotor Control Schemes, PhD thesis, Department of Aerospace Engineering, University of Bristol, 1999.Google Scholar
10. Howrrr, J., Howell, S.E., Brinson, P.R., Mullen, G.J., Woodrow, I. and Hayhurst, C. Experimental evaluation of high bandwidth helicopter flight control system designs exploiting rotor state feedback, 23rd European Rotorcraft Forum, Dresden, 1997.Google Scholar
11. Brinson, P.R., Mullen, G.J., Woodrow, I. and Howitt, J. Experimental evaluation of control system design methods for helicopters, 21st European Rotorcraft Forum, St. Petersburg, 1995.Google Scholar
12. Tischler, M.B. System identification requirements for high-bandwidth rotorcraft flight control system design, J Cuid, Cont Dyn, 1990, 13, (5).Google Scholar
13. Curtiss, H.C. Stability and control modelling, Vertica, 1988, 12, (4).Google Scholar
14. Padfield, G.D., McCallum, A.T., Haverdings, H., Dequin, A.M., Haddon, D., Kampa, K., Basset, P.M. and Vongrunhagen, W. Predicting rotorcraft flying qualities through simulation modelling, a review of key results from Garteur AG606, 22nd European Rotorcraft Forum, Brighton, 1996.Google Scholar
15. Glover, K. and Mcfarlane, D. Robust stabilisation of normalised coprime factor plant descriptions with H-infinity bounded uncertainty, IEEE Trans Auto Con, 1989, 34, (8).Google Scholar
16. Sefton, J. and Glover, K. Pole/zero cancellations in the general H-infinity problem with reference to a two block design, Sys Con Letters, 1990, 14.Google Scholar
17. Hyde, R.A. The Application of Scheduled H-infinity Controllers to a VSTOL Aircraft, PhD thesis, University of Cambridge, 1991.Google Scholar
18. Walker, D. and Postlethwaite, I. Advanced helicopter flight control using two-degree-of-freedom H-infinity optimisation, J Guid, Con Dyn, 1996,19,(2).Google Scholar
19. Baillie, S.W. and Murray-Morgan, J. Practical experiences in control system design using the NCR Bell 205 airborne simulator, AGARD CP-560, Active Control Technology: Applications and Lessons Learned, Published 1995.Google Scholar
20. Multivariate frequency domain toolbox user's guide, Version 2.4, Cambridge Control/ The Mathworks, 1993.Google Scholar
21. Mu-analysis and synthesis toolbox user's guide, Version 2.0, The Math-works, 1993.Google Scholar