Design, modelling and simulation of 2 novel 6 DOF hybrid machines.
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Date
2012
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Abstract
Industrial robot arms are an essential part of automated manufacturing, and perform tasks
such as component assembly, welding, light machining, spray painting, etc. They are highly
repeatable, can be calibrated to be sufficiently accurate and they eliminate human error. The
serial robot architecture is by far the most ubiquitous in modern day manufacturing, as the
technology is highly refined in its current state; the machine architecture provides great
dexterity and it has a large useful workspace. This architecture however does have some
problems, one of which is a large machine moving mass. The primary reason for this lies in
the location of its motors and gearboxes. Due to the robot's significant inertia it utilizes a
large amount of energy.
This thesis focused on the mechanical design, mathematical modelling and simulation of 2
robotic arm designs which had a hybrid nature. They were classified as hybrid due to the fact
that their architectures departed from both the classic definitions of serial kinematics
manipulators/machines (SKMs) and parallel kinematics manipulators/machines (PKMs). The
primary design goal was to merge some of the advantages of both architectures, i.e. a large
workspace to footprint ratio and high end-effector dexterity which was found in serial robots,
combined with the low inertia of a parallel robot for improved dynamics. Serial and parallel
robots were complementary, and these design goals could not co-exist in a single purist robot
architecture. The designs had a full complement of 6 DOFs (degrees of freedom), 3 DOFs for
spatial position of the wrist and 3 DOFs for orientation of that wrist. They also had a lower
machine moving mass, a fact that was thought to improve speed and energy usage. A major
contribution of this research PhD project was a comparative energy usage study, which was
performed against the serial robot as a measure. This was done for both hybrid designs as
well as another model which represented 2 existing patented designs. The purpose of that
was to determine if lowering the machine moving mass would improve energy efficiency, and
to determine which design was best.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.
Keywords
Robots, Industrial., Robots--Kinematics., Robots--Motion., Automatic machinery., Theses--Mechanical engineering.