Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: A strategy for the design of an effective, practically feasible, robust, computationally efficient
autopilot for three dimensional manoeuvre flight control of Unmanned Aerial Vehicles is
presented. The core feature of the strategy is the design of attitude independent inner loop
acceleration controllers. With these controllers implemented, the aircraft is reduced to a point
mass with a steerable acceleration vector when viewed from an outer loop guidance
perspective. Trajectory generation is also simplified with reference trajectories only required
to be kinematically feasible. Robustness is achieved through uncertainty encapsulation and
disturbance rejection at an acceleration level.
The detailed design and associated analysis of the inner loop acceleration controllers is carried
out for the case where the airflow incidence angles are small. For this case it is shown that
under mild practically feasible conditions the inner loop dynamics decouple and become
linear, thereby allowing the derivation of closed form pole placement solutions. Dimensional
and normalised non-dimensional time variants of the inner loop controllers are designed and
their respective advantages highlighted. Pole placement constraints that arise due to the
typically weak non-minimum phase nature of aircraft dynamics are developed.
A generic, aircraft independent guidance control algorithm, well suited for use with the inner
loop acceleration controllers, is also presented. The guidance algorithm regulates the aircraft
about a kinematically feasible reference trajectory. A number of fundamental basis trajectories
are presented which are easily linkable to form complex three dimensional manoeuvres.
Results from simulations with a number of different aircraft and reference trajectories illustrate
the versatility and functionality of the autopilot.
Key words: Aircraft control, Autonomous vehicles, UAV flight control, Acceleration control,
Aircraft guidance, Trajectory tracking, Manoeuvre flight control. / AFRIKAANSE OPSOMMING: ’n Strategie vir die ontwerp van ’n effektiewe, prakties haalbaar, robuuste, rekenkundig
effektiewe outoloods vir drie dimensionele maneuver vlugbeheer van onbemande vliegtuie
word voorgestel. Die kerneienskap van die strategie is die ontwerp van oriëntasie-onafhanklike
binnelus-versnellingbeheerders. Hierdie beheerders stel die navigasie buitelus in staat om die
voertuig as ’n puntmassa met ’n stuurbare versnellingsvektor te beskou. Trajekgenerasie is ook
vereenvoudig deurdat verwysingstrajekte slegs kinematies haalbaar hoef te wees. Robuustheid
word verkry deur onsekerhede en versteuringsverwerping op ’n versnellingsvlak te hanteer.
Die gedetaileerde ontwerp en saamhangende analise van die binnelus versnellingsbeheerders
word uitgevoer vir die geval waar die invalshoeke klein is. Dit word aangetoon dat, onder
praktiese omstandighede, die binnelus dinamika ontkoppel kan word en lineêr word, wat die
afleiding van geslotevorm poolplasingoplossings toelaat. Dimensionele en genormaliseerde,
nie-dimensionele tydvariante van die binnelusbeheerders word ontwerp en hul onderskeidelike
voordele word uitgewys. Poolplasing beperkings, wat ontstaan as gevolg van die tipiese
geringe nie-minimum fasegedrag van voertuigdinamika, word ontwikkel.
’n Gepaste generiese, voertuig onafhanklike navigasiebeheer algoritme vir gebruik saam met
die binnelus-versnellingsbeheerders word voorgestel. Die voertuig word om ’n kinematies
haalbare verwysingstrajek deur hierdie navigasie algoritme gereguleer. ’n Aantal fundamentele
trajekte word voorgestel wat maklik gekombineer kan word om komplekse drie dimensionele
maneuvers te vorm. Die veelsydigheid en funksionaliteit van die outoloods word deur
simulasieresultate met ’n verskeidenheid voertuie en verwysingstrajekte gedemonstreer.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/44331 |
| Date | 12 1900 |
| Creators | Peddle, Iain K. |
| Contributors | Jones, T., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xv, 264 p. : ill. |
| Rights | Stellenbosch University |
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