Feedback control of a shape memory alloy actuator for control surface deflection
Ehlers, Righardt Frederick (2012-03)
ENGLISH ABSTRACT: The successful design, implementation and testing of a feedback control system for
tab-deflection control of a shape memory alloy (SMA) based control surface actuator
is presented. The research is performed as part of the Control Surfaces in Confined
Spaces (CoSICS) research project conducted at Stellenbosch University. The research
group investigates ways to provide control surface actuation in size-restricted spaces
in commercial aircraft such as the Airbus A320 and A330. This is achieved by investigating
the concept of trailing edge tabs to reduce the required torque load, resulting
in reduced actuator requirements enabling the use of smaller actuators. This thesis
contributes to the project by investigating the possibility of using SMA-based actuators
in reduced hinge moment requirement applications.
An SMA-based tab actuator demonstrator design is presented. Mathematical models
are derived for the SMA material, thermodynamics and actuator geometry. The models
are combined to formulate an SMA-based control surface actuator model. The model is
utilised in four tracking feedback controller designs; two based on linear and two based
on non-linear control techniques.
The manufactured prototype is presented along with the incorporated hardware for
controller implementation. System identification follows and validates the three mathematical
Practical verification of the model and two of the controllers is conducted. The unimplemented
controllers are implemented through a validated model simulation. Controller
evaluation, based on the dynamic controller performance, is conducted. The results
validate the concept of using an SMA actuator for tab-deflection control and indicate
important limitations for the intended application.
AFRIKAANSE OPSOMMING: Die tesis behels die ontwerp, implementering en toetsing van ’n terugvoer beheerstelsel
vir hulpvlak defleksie beheer van ’n vorm-geheue allooi (SMA) gebaseerde aktueerder.
Die navorsing vorm deel van die Beheervlakke in Begrensde Ruimtes (CoSICS) navorsingsprojek
by Stellenbosch Universiteit. Die CoSICS navorsing behels ’n ondersoek na
beheervlak aktueering in beknopte spasies in kommersiële vliegtuie soos die Airbus
A320 en A330. Die probleem word aangespreek deur ’n ondersoek na aerodinamiese
hulpvlakke wat ’n vermindering in skarnier moment tot gevolg het en sodoende die
aktueerder vereistes verminder.
Hierdie tesis dra by tot die projek deur die moontlikheid van die gebruik van SMAgebaseerde
aktueerders in verminderde skarnier moment vereiste toepassings te ondersoek.
‘n SMA gebaseerde hulpvlak demonstrasie aktueerder ontwerp word voorgelê. Wiskundige
modelle vir die SMA materiaal, termodinamika en prototipe geometrie is geformuleer
en gekombineer om ‘n SMA gebaseerde beheervlak aktueerder model te ontwikkel.
Die model word in vier beheerder ontwerpe toegepas. Twee ontwerpe is op
liniëre en twee op nie-liniëre beheer tegnieke gebaseer.
Die prototipe en nodige hardeware vir beheerder implementasie is voorgedra. Stelsel
identifikasie is toegepas en verifieer die drie wiskundige modelle.
Praktiese verifikasie van die model en twee beheerders is gedoen. Die ongeïmplementeerde
beheerders is deur die geverifieerde aktueerder model gesimuleer. ‘n Beheerder
evaluasie gebaseer op die dinamiese beheerder gedrag word toegepas. Die
evaluasie beklemtoon kritiese aspekte en beperkinge in verband met SMA aktueering.
Die resultate regverdig die gebruik van ‘n SMA aktueerder vir hulpvlak defleksie beheer
en beklemtoon belangrike beperkinge ten opsigte van die voorgestelde toepassing.
Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/19977