Implementation of an explicit reference governor in a nonlinear quadcopter system

Permanent URL: http://hdl.handle.net/2047/D20200246
Title:
Implementation of an explicit reference governor in a nonlinear quadcopter system
Creator:
de Quadros, Oliver (Author)
Contributor:
Sznaier, Mario (Advisor)
Sznaier, Mario (Committee member)
Shafai, Bahram (Committee member)
Sipahi, Rifat (Committee member)
Language:
English
Publisher:
Boston, Massachusetts : Northeastern University, 2015
Date Accepted:
December 2015
Date Awarded:
January 2016
Type of resource:
Text
Genre:
Masters theses
Format:
electronic
Digital origin:
born digital
Abstract/Description:
Quadcopters are inherently nonlinear systems but can be linearized over a small range of pitch (θ) and roll (φ) angles and therefore are able to use standard linear feedback controllers to minimize steady state errors and improve tracking performance. However, these controllers are usually subjected to saturation in order to keep the system in the linear region. The nonlinearities arising from these saturations are generally not acceptable since they can cause errors which do not converge and long settling times. In this thesis, we discuss and implement an Explicit Reference Governor (ERG) that attenuates the XY-references to the Quadcopter when constraint violations may occur in order to maintain stability. This is done by creating upper bounds on the value of the Lyapunov function from system constraints. These bounds are then enforced by changing the velocity of the reference command. This ERG is preferable due to its low computation times and because it provides a consistent closed-form control law regardless of system. The theory of the ERG is presented along with the nonlinear and linear models of the Quadcopter in which the constraints of the system are established. The ERG is then implemented in a simulation platform of the Quadcopter and is tested and compared to the Quadcopter model with and without saturation. The implemented ERG improved the settling time of the system by 15% compared to the saturated system and was able to stay within the allowable limits unlike the unsaturated system.
Subjects and keywords:
add-on controller
nonlinear control
quadcopter
quadrocopter
reference governor
UAV
Drone aircraft -- Control systems -- Mathematical models
Quadrotor helicopters -- Automatic control -- Mathematical models
Nonlinear control theory
Nonlinear theories
Linear systems
DOI:
https://doi.org/10.17760/D20200246
Permanent Link:
http://hdl.handle.net/2047/D20200246
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