Design Optimization and Control of a Fully Actuated Hexrotor UAV for Use in Aerial Manipulation Applications
Jameson Yau Sung Lee · Digital Scholarship - UNLV (University of Nevada Reno) · 2020
This work addresses the issue of controller complexity in the application of a special class of multirotor in aerial manipulation tasks. Much of the current research concerning aerial manipulation involves the modeling and control of highly coupled multirotor and manipulator systems. This is a consequence of the platform's under-actuation condition. To accommodate the rejection of arbitrary wrench disturbances brought about by the environment, multirotor must perform deliberate attitude tracking to affect forward and lateral maneuvers mid-flight. The manipulator end-effector tracking is highly affected by this, thus, their performance in general aerial manipulation is limited. To address these limitations, a special class of fully-actuated hexrotor platform was developed in this work. First, a classification system for multirotor models was introduced, and the analytical solution for all multirotor classes capable of expressing a decoupled wrench was derived. Design metrics were developed based on non-dimensional comparisons of traditional multirotor of the same form-factor. In this way, a qualitative assessment of fully-actuated multirotor performance can be compared to traditional platforms. In addition, the constraint spaces for force production and general attitude production were developed. It was shown through analysis that wrench production is inherently dependent on direction of allocation, since there are a finite number of rotors in any given multirotor build. Lastly, nonlinear control and prototype development were discussed as they relate to firmware development. The compliance of the firmware with the existing ArduPilot Mega (APM) firmware, provide a reasonable justification for commercial use.