A dissertation submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements
for the degree of Master of Science in Engineering.
Johannesburg, April 2016 / A Rotary Wing Unmanned Aerial Vehicle (RW UAV) as a platform and its payload
consisting of sophisticated sensors would be costly items. Hence, a RW UAV in the
500 kg class designed to fulfil a number of missions would represent a considerable
capital outlay for any customer. Therefore, in the event of an engine failure, a means
should be provided to get the craft safely back on the ground without incurring
damage or causing danger to the surrounding area. The aim of the study was
to design a controller for autorotative landing of a RW UAV in the event of engine
failure. In order to design a controller for autorotative landing, an acceleration model
was used obtained from a study by Stanford University. FLTSIM helicopter flight
simulation package yielded necessary RW UAV response data for the autorotation
regimes. The response data was utilized in identifying the unknown parameters
in the acceleration model. A Differential Dynamic Programming (DDP) control
algorithm was designed to compute the main and tail rotor collective pitch and the
longitudinal and lateral cyclic pitch control inputs to safely land the craft. The
results obtained were compared to the FLTSIM flight simulation response data.
It was noted that the mathematical model could not accurately model the pitch
dynamics. The main rotor dynamics were modelled satisfactorily and which are
important in autorotation because without power from the engine, the energy in
main rotor is critical in a successful execution of an autorotative landing. Stanford
University designed a controller for RC helicopter, XCell Tempest, which was deemed
successful. However, the DDP controller was designed for autonomous autorotative
landing of RW UAV weighing 560 kg, following engine failure. The DDP controller
has the ability to control the RW UAV in an autorotation landing but the study
should be taken further to improve certain aspects such as the pitch dynamics and
which can possibly be achieved through online parameter estimation. / MT 2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/23516 |
| Date | January 2016 |
| Creators | Matlala, Puseletso |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (xvi, 126 leaves), application/pdf, application/pdf |
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