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The Development of Neural Network Based System Identification ...

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2.1 INTRODUCTION 17<br />

• Inefficient flight dynamics: lower maximum speed, shorter mission range.<br />

• More accurate and complicated navigation sensor requirement.<br />

• Inherently unstable and relatively poorly known dynamics. Difficult control system<br />

design.<br />

Typical helicopters or rotorcraft based UAS are classified into five categories that<br />

differ on several characteristics [Kendoul, 2012, Eisenbeiss, 2004]. Figure 2.1 shows<br />

the classification <strong>of</strong> helicopter UAS based on attributes such as the total weight <strong>of</strong> the<br />

aircraft, payload, range, service ceiling and endurance. Most unmanned aerial vehicle<br />

platforms available at the University <strong>of</strong> Canterbury consist <strong>of</strong> rotorcraft based UAS<br />

from Category 3 and 4. <strong>The</strong> UAS from Category 3 is based on commercially available<br />

remote control (RC) helicopter and requires considerable amount <strong>of</strong> work to integrate<br />

the autopilot system into the aerial platform. Nevertheless, the aerial platform used in<br />

this research was selected from Category 3 UAS which <strong>of</strong>fers larger payload capacity and<br />

longer endurance than Category 4 or 5. Thus, better payload capacity and endurance<br />

would make the selection <strong>of</strong> Category 3 UAS much more suitable for longer monitoring<br />

and surveillance applications such as aerial mapping, cinematography, high structure<br />

inspection and natural disaster damage assessment.<br />

A helicopter based UAS requires three main autonomy elements such as guidance,<br />

navigation and control (GNC) to enable them to execute above-mentioned missions<br />

autonomously. <strong>The</strong> overview <strong>of</strong> autonomous system components for helicopter based<br />

UAS is given in Figure 2.2. As described in Kendoul [2012], the navigation function for<br />

helicopter UAS involves the process <strong>of</strong> acquisition and analysis <strong>of</strong> sensory data and how<br />

to use them to infer the vehicle’s state informations (position, orientation, velocity).<br />

<strong>The</strong> navigation process also includes the capabilities to build an internal model <strong>of</strong><br />

the surrounding environments within UAS operation using perception techniques such<br />

as mapping, object recognition, obstacle and target detection. <strong>The</strong>se capabilities are<br />

essential for operating a UAS to ensure that it can successfully complete an assigned<br />

mission. <strong>The</strong> guidance function for a helicopter based UAS demonstrate the high level<br />

planning and decisions making process to enable successful missions or goal execution.

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