simulating actuator energy demands of an aircraft in flight

431 Pages·2014·18.17 MB·English

CRANFIELD UNIVERSITY
Michael Anthony Cooper
SIMULATING ACTUATOR ENERGY
DEMANDS OF AN AIRCRAFT IN FLIGHT
SCHOOL OF ENGINEERING
Department of Aerospace Engineering
Ph.D. THESIS
Academic Year: 2014
Supervisor: Dr Craig Lawson
February 13, 2014

Cranfield University
School of Engineering
Department of Aerospace Engineering
Ph.D. THESIS
Academic Year: 2014
Michael Anthony Cooper
Simulating Actuator Energy Demands of an
Aircraft in Flight
Supervisor: Dr Craig Lawson
February 13, 2014
This thesis is submitted in partial fulfilment of the requirements for the
degree of Doctor of Philosophy
©
Cranfield University 2014. All rights reserved. No part of this publication
may be reproduced without the written permission of the copyright owner.

Abstract
This thesis contributes towards the discipline of whole aircraft simula-
tion; modelling flight dynamics and airframe systems simultaneously. The
objective is to produce estimates of the dynamic power consumption char-
acteristics of the primary flight control actuation system when executing
manoeuvres. Three technologies are studied; the classic hydraulic actuators
and the electromechanical and electro-hydrostatic types that are commonly
associated with the more electric aircraft.
Models are produced which represent the flight dynamics of an aircraft;
these are then combined with low frequency dynamic functional models of
the three actuator technologies and flight controllers. The result is a model,
capable of faster than real time simulation, which produces estimates of ac-
tuator power consumption as the aircraft follows predefined trajectories.
The model is used to quantify the energy consumption as a result of
different manoeuvre rates when executing banked turns. The result from an
actuation system point of view alone is that the lower the turn rate, the lower
the overall energy used. The tradeoff is that the turn radius becomes larger.
The use of the model can be extended to assist with additional design
challenges such as actuator design and specification. Using methods to size
actuators based on stall force and no load speed properties leads to oversizing
of the control system. Performing dynamic analyses is usually a combined
task of laboratory based actuator test rigs stimulated by input data gathered
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during flight tests. The model in this work provides a method of generating
data for preliminary design; therefore reducing the amount of flight testing
required in a design and certification programme.
The major results discovered using the tools developed in this thesis are
that a hydraulically powered aileron uses 4.23% more energy to achieve a
turn at a heading rate of 0.03 rad/s compared to a 0.005 rad/s manoeuvre
in the same conditions. The electromechanical actuator (EMA) uses 1.67%
more and the electrohydrostatic actuator (EHA) uses 1.54% more to achieve
the same turns. It implies reduced turn rate turns would have the largest
benefit for reducing energy consumption in current hydraulically powered
actuation systems, compared to electrical actuators.
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Acknowledgement
This thesis has consumed more days, nights and weekends than I would
wish to put a number on. A student working towards a doctorate will find
themselves‘intheoffice’atmosttimesoftheday; whetherbehindacomputer
or at home with work on the mind. Those that have not suffered it will not
understand it, but those that have; will never regret it.
Me, I find my forehead slightly flattened from the number of times head
has met desk; as I cried for Matlab’s prowess at producing undecipherable
error messages. I reminisce of solving the umpteenth ‘one more problem’
while friends and family suggested much more exciting events than wearing
the lettering off my keyboard. Indeed, it was pointed out early on that while
asupervisorisimperativefortechnicalguidance; agoodpartoftheirpurpose
is to maintain the sanity of their students on the lonely journey.
Unfortunately,Icannotsaythesameforthosetwokeyboardsthatdecided
to part ways with me in the process; but my supervisor did a marvellous job
of balancing support, guidance and leaving the student to their own devices
(and providing the odd sanity check). To him I offer my greatest thanks;
both for the support and the opportunity.
Academia aside, I loathe to think where I would be without the personal
support that has endured the last four years with me. My partner Claire
has smiled and nodded through countless boring descriptions of the finer
points of aileron behaviour. She knew when to give me space (during the
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aforementioned head-meeting-desk periods) and when to provide support.
MyhousemateShakeelprovidedseeminglyendlessdiscussiononthetopicsof
simulation, flight dynamics, actuator mechanics, aerodynamics and generally
anything too geeky to be mentioned in general society.
A document such as this would probably be most appropriately measured
by mass or volume, rather than word counts or pages. A publication of this
mass can hardly go without gratitude towards my parents, who have pushed
me, supported me and criticised me when appropriate.
Cranfield itself has provided a raft of support which does not fit anywhere
else in this acknowledgement; the Clean Sky team, Daniele, Usman, Ravinka
and Shinkafi for discussions on the sponsoring industrial project and other-
wise. Barry Walker who, quite frankly, the experimental work would not
have been possible without.
Unwittingly, those that have made work at Cranfield more difficult also
deserve thanks; you bestow upon people the experience of what is inevitable
in professional life, thus you allow us to grow.
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Contents
Abstract i
Acknowledgement iii
Table Of Contents v
List Of Figures x
List Of Tables xviii
Nomenclature xxi
Acronyms xxvii
1 Introduction 1
1.1 Overview and Motivation . . . . . . . . . . . . . . . . . . . . . 1
1.2 Research Novelty and Publications . . . . . . . . . . . . . . . 4
1.3 Thesis Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Literature Review 7
2.1 The Case for Optimisation . . . . . . . . . . . . . . . . . . . . 7
2.2 Combined Aircraft and Systems Simulation . . . . . . . . . . . 10
2.3 Actuation Systems . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.1 Current Actuator Trends and the More Electric Aircraft 12
2.3.2 Hydraulic Actuators . . . . . . . . . . . . . . . . . . . 17
2.3.2.1 Description . . . . . . . . . . . . . . . . . . . 17
2.3.2.2 Development Programmes . . . . . . . . . . . 19
2.3.2.3 Robust Design . . . . . . . . . . . . . . . . . 21
2.3.2.4 Component Specification . . . . . . . . . . . . 22
2.3.3 Electromechanical Actuators . . . . . . . . . . . . . . . 25
2.3.3.1 Description . . . . . . . . . . . . . . . . . . . 25
2.3.3.2 Flight Test and Development Programmes . . 27
2.3.3.3 Robust Design . . . . . . . . . . . . . . . . . 32
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2.3.3.4 Regeneration . . . . . . . . . . . . . . . . . . 38
2.3.3.5 Component Specification . . . . . . . . . . . . 40
2.3.4 Electro-hydrostatic Actuators . . . . . . . . . . . . . . 50
2.3.4.1 Description . . . . . . . . . . . . . . . . . . . 50
2.3.4.2 Flight Test and Development Programmes . . 52
2.3.4.3 Robust Design . . . . . . . . . . . . . . . . . 61
2.3.4.4 Regeneration . . . . . . . . . . . . . . . . . . 63
2.3.4.5 Component Specification . . . . . . . . . . . . 63
2.3.5 Power Loss Modelling . . . . . . . . . . . . . . . . . . 64
2.4 Aircraft Modelling . . . . . . . . . . . . . . . . . . . . . . . . 73
2.4.1 Coordinate Frames . . . . . . . . . . . . . . . . . . . . 74
2.4.2 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . 74
2.4.2.1 Translational Velocity . . . . . . . . . . . . . 74
2.4.2.2 Rotational Velocity . . . . . . . . . . . . . . . 75
2.4.3 Rigid Body Dynamics . . . . . . . . . . . . . . . . . . 76
2.4.3.1 Translational Motion . . . . . . . . . . . . . . 76
2.4.3.2 Rotational Motion . . . . . . . . . . . . . . . 78
2.4.4 Equations of Motion . . . . . . . . . . . . . . . . . . . 83
2.4.5 External Forces and Moments . . . . . . . . . . . . . . 83
2.4.5.1 Gravitational Forces . . . . . . . . . . . . . . 84
2.4.5.2 Aerodynamic Forces and Moments . . . . . . 85
2.4.5.3 Propulsive Forces and Moments . . . . . . . . 88
2.4.6 Aerodynamic Load Estimation . . . . . . . . . . . . . . 89
2.5 Flight Control and Guidance . . . . . . . . . . . . . . . . . . . 91
2.5.1 Classic Single Input - Single Output flight control al-
gorithms . . . . . . . . . . . . . . . . . . . . . . . . . . 92
2.5.1.1 SISO Overview . . . . . . . . . . . . . . . . . 92
2.5.1.2 SISO Implementation . . . . . . . . . . . . . 95
2.5.2 Total Energy Control System . . . . . . . . . . . . . . 96
2.5.2.1 TECS Overview . . . . . . . . . . . . . . . . 96
2.5.2.2 TECS Implementation . . . . . . . . . . . . . 101
2.5.2.3 Performance Demonstration . . . . . . . . . . 106
2.5.3 Total Heading Control System . . . . . . . . . . . . . . 109
2.5.3.1 THCS Overview . . . . . . . . . . . . . . . . 109
2.5.3.2 THCS Implementation . . . . . . . . . . . . . 109
2.5.3.3 Performance Demonstration . . . . . . . . . . 113
2.5.4 Guidance Algorithm . . . . . . . . . . . . . . . . . . . 116
2.5.4.1 Performance Demonstration . . . . . . . . . . 123
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