3D dynamic modeling of spherical wheeled self-balancing mobile robot
Author
İnal, Ali Nail
Advisor
Morgül, Ömer
Date
2012Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
In recent years, dynamically stable platforms that move on spherical wheels, also
known as BallBots, gained popularity in the robotics literature as an alternative
locomotion method to statically stable wheeled mobile robots. In contrast to
wheeled platforms which do not have to explicitly be concerned about their balance,
BallBot platforms must be informed about their dynamics and actively try
to maintain balance. Up until now, such platforms have been approximated by
simple planar models, with extensions to three dimensions through the combination
of decoupled models in orthogonal sagittal planes. However, even though
capturing certain aspects of the robot’s motion is possible with such decoupled
models, they cannot represent inherently spatial aspects of motion such as yaw
rotation or coupled inertial effects due to the motion of the rigid body.
In this thesis, we introduce a novel, fully-coupled 3D model for such spherical
wheeled balancing platforms. We show that our novel model captures important
spatial aspects of motion that have previously not been captured by planar
models. Moreover, our new model provides a better basis for controllers that
are informed by more expressive system dynamics. In order to establish the expressivity
and accuracy of this new model, we present simulation studies in dynamically
rich situations. We use circular paths to reveal the advantages of the
new model for fast maneuvers. Additionally, we introduce new inverse-dynamics
controllers for a better attitude control and investigate within simulations the
capability of sustaining dynamic behaviors. We study the relation between circular
motions in attitude angles and associated motions in positional variables
for BallBot locomotion.
Keywords
Dynamic ModelingBalancing Mobile Robots
Underactuated Systems
Dynamic System Control
Attitude Control