Electrical and Computer Engineering ETDs

Publication Date

2-1-2016

Abstract

The purpose of this thesis is to outline the development of a high-performance quadrotor control system for an AscTec Hummingbird quadrotor using direct motor speed control within a Vicon motion capture system environment. A Ground Control Station (GCS) acts as a user interface for selecting flight patterns and displaying sensor values. An on-board Intel Edison embedded Linux computer acts as the quadrotor's controller. The Vicon system measures the quadrotor's position and orientation, while the Hummingbird's stock AscTec Autopilot board provides inertial measurements and receives motor speed commands. Based on the flight pattern set by the GCS, smooth and di erentiable trajectories are generated. A control program was written for the Edison to obtain measurements, receive flight pattern commands, perform state estimation, calculate control laws, send motor speed commands to the Autopilot board, and log values. The program was written as a multithreaded C++ program for increased performance. A feedback linearization of the quadrotor's dynamics was performed to account for its nonlinearities. A controller structure designed to ensure exponential Lyapunov stability was applied to the input-output linearized dynamics. The simplex method was used to aid the controller in pushing the Hummingbird's actuators for aggressive maneuvers within set input limitations. The Edison's Wi-Fi capabilities enable it to contact the Vicon server directly for position and orientation measurements. Accelerations and angular velocities are measured by the Autopilot's inertial measurement unit (IMU). A quick state estimation process was implemented to filter the measured states, and state prediction was used to compensate for latency in the system. A custom circuit board and communication framework was designed and assembled for interfacing the Edison with the Autopilot. The custom communication framework allowed for a 16 times speed improvement over the default settings while bypassing the stock wireless communication's inherently unreliable timing. The Hummingbird's physical properties, such as propeller performance and rotational inertias, were characterized via static and step response experiments. The control system's flight performance was evaluated through simulation and experimental tests.

Keywords

Quadrotor, Control, Feedback Linearization, State Estimation, AscTec Hummingbird

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Abdallah, Chaouki

Second Committee Member

Poroseva, Svetlana

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