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Designing, Modeling and Control of a Tilting Rotor Quadcopter

Nemati, Alireza

Abstract Details

2016, PhD, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
The aim of the present work is to model, design, control, fabricate and experimentally study quadcopter with tilting propellers. A tilting quadcopter is an aerial vehicle whose rotors can tilt along axes perpendicular to their respective axes of rotation. The tilting rotor quadcopter provides the added advantage in terms of additional stable configurations, made possible by additional actuated controls, as compared to a traditional quadcopter without titling rotors. The tilting rotor quadcopter design is accomplished by using an additional motor for each rotor that enables the rotor to rotate along the axis of the quadcopter arm. Conventional quadcopters, due to limitation in mobility, belong to a class of underactuated robots which cannot achieve any arbitrary desired state or configuration. For example, the vehicle cannot hover at a defined point at a tilted angle. It needs to be completely horizontal in order to hover. An attempt to achieve any pitch or roll angle would result in forward (pitch) motion or lateral (roll) motion. This proposed tilting rotor concept turns the traditional quadcopter into an over-actuated flying vehicle allowing us to have complete control over its position and orientation. In this work, a dynamic model of the tilting rotor quadcopter vehicle is derived for flying and hovering modes. The model includes the relationship between vehicle orientation angles and rotor tilt-angles. Furthermore, linear and nonlinear controllers have been designed to achieve the hovering and navigation capability while having any desired pitch and/or roll orientation. In the linear approach, the four independent speeds of the propellers and their rotations about the axes of quadcopter arms have been considered as inputs. In order to start tracking a desired trajectory, first, hovering from the initial starting point is needed. Then, the orientation of the vehicle to the desired pitch or roll angle is obtained. Subsequently, any further change in pitch or roll angles, obtained using a linear controller, result in motion of the quadcopter along the desired trajectory. The dissertation then presents a nonlinear strategy for controlling the motion of the quadcopter. The overall control architecture is divided into two sub-controllers. The first controller is based on the feedback linearization control derived from the dynamic model of the tilting quadcopter. This controls the pitch, roll, and yaw motions required for movement along an arbitrary trajectory in space. The second controller is based on two Proportional Derivative (PD) controllers which are used to control the tilting of the quadcopter independently along the pitch and the yaw directions respectively. The overall control enables the quadcopter to combine tilting and movement along a desired trajectory simultaneously. Furthermore, the stability and control of tilting-rotor quadcopter is presented upon failure of one propeller during flight. On failure of one propeller, the quadcopter has a tendency of spinning about the primary axis fixed to the vehicle as an outcome of the asymmetry about the yaw axis. The tilting-rotor configuration is an over-actuated form of a traditional quadcopter and it is capable of handling a propeller failure, thus making it robust in one propeller failure during the flight. The dynamics of the vehicle once the failure accrued is derived and a controller is designed to achieve hovering and navigation capability. The dynamic model and the controller of the vehicle were verified with the help of numerical studies for diff erent flight scenarios as well as failure mode. Subsequently, two diff erent models of the vehicle were designed, fabricated and tested. Experimental results have validated the dynamical modeling and the flight controllers.
Manish Kumar, Ph.D. (Committee Chair)
Ali Minai, Ph.D. (Committee Chair)
Raj Bhatnagar, Ph.D. (Committee Member)
Kelly Cohen, Ph.D. (Committee Member)
Rui Dai, Ph.D. (Committee Member)
113 p.

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Citations

  • Nemati, A. (2016). Designing, Modeling and Control of a Tilting Rotor Quadcopter [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470672220

    APA Style (7th edition)

  • Nemati, Alireza. Designing, Modeling and Control of a Tilting Rotor Quadcopter. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470672220.

    MLA Style (8th edition)

  • Nemati, Alireza. "Designing, Modeling and Control of a Tilting Rotor Quadcopter." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470672220

    Chicago Manual of Style (17th edition)