173 research outputs found
Hybrid Cfd-Nnarx Modelling Of Single Mrf Valve For Visual Servoing.
Magnetorheological fluid (MRF) actuator emerged in the last decade as a
potential system to replace electro-hydraulic servo system in precision applications. A
complete closed-loop control system is necessary to support the accuracy of the
system. Modelling of the valve is a crucial task in developing an optimal control
system for the valve, but the knowledge of fluid behaviour inside the valve channel
remains scarce. This research aims to develop a plant model of MRF actuator using
the system identification approach, where the Computational Fluid Dynamics (CFD)
result is used as an input. The plant model is then used to design a closed-loop control
system for the MRF actuator. To achieve this objective, a 3D CFD model was
developed, and a steady state analysis was run to study fluid behaviours in the channel.
Transient analysis with dynamic input was further performed to study the correlation
between the current input and the volume flow rate as an output. Neural network
nonlinear autoregressive network with exogenous inputs (NNARX) used data from the
CFD to identify the plant model of an MRF valve. The result acquired from the CFD
simulation and plant model gave good agreement with the experimental result with an
error of less than 3%. The velocity in the MRF valve reduced 85% when the current
varied from 0 to 0.8A. The hybrid CFD-NNARX model shows a small deviation from
the experimental result with an average error of 4%. As a conclusion, the hybrid CFDNNARX
has been proven useful in modelling the MRF actuator. The main
contribution of this work is the plant model of an MRF actuator, which can be utilised
as an input in controller design process of MRF actuator
Brake Steer Torque Optimized Corner Braking of Motorcycles
This thesis deals with the Brake Steer Torque (BST) induced stand-up tendency of Powered Two Wheelers (PTW) and measures to lower the associated risk for running wide on curve accidents with sudden, unforeseen braking. Focus is set on the BST Avoidance Mechanism (BSTAM), a chassis design that eliminates the BST through lateral inclination of the kinematic steering axis. A simple mathematical model is used to identify its main influences on the driving behavior and derive an optimized system layout. Its theoretical potential is evaluated against the standard chassis using different cornering adaptive brake force distributions and riding styles. For the first time ever, a motorcycle with state-of-the-art brake system (Honda CBR 600 RR, C-ABS) is equipped with a BSTAM and tested in corner braking experiments. Compared to the baseline, it is significantly reducing BST related disturbances and improving directional control. The gained insights can be stepping stones to enhance PTW safety by enabling future assistance systems with autonomous corner braking
Sensitivity analysis and optimal design of conventional and magnnetorheological fluid brakes
Mechanical and electrical brakes have dominated the braking industry for many years and will most likely continue to do so for the foreseeable future due to their low cost and adequate operating performance, wide range of applications, vehicle engineering, civil engineering, and biomedical engineering. Simple mechanical drum brake and magnetorheological (MR) fluid brake have presented in the current work. The main objective of this work is to increase braking torque, and to develop a new optimal design of MR fluid brake with better design and design control of the MR fluid design. To do so, four important steps have been accomplished. In the first step, a mathematical modeling of the conventional frictional brake and MR fluid brake has been developed to study and specify all design parameters. In the second step, a nondimensional, closedform analysis and a Taylor series expansion have used to examine the effects of perturbing dimensionless design parameters on the overall brakes performance. In the third step, two optimal designs for MR fluid brakes have been developed by taking advantage of sensitivity analysis and the design of experiments method also known as the Taguchi method. In the fourth step, controlling a MR fluid brake is performed by using two parallel PI controls for controlling the magnetic current and MR fluid thickness simultaneously. It was concluded that sensitivity analysis is a good method for identifying the parameters that have the greatest impact on brake performance and can be used as one method for the designer to obtain an optimal design. Four nondimensional design parameters were successfully used to describe the conventional frictional brake and seven nondimensional design parameters for MR fluid brake. Only two parameters for the conventional brake and five parameters for the MR fluid brake affect the performance and the others can be neglected. Two new designs for the MR fluid brake are presented and shown to be very simple in design, low in cost by removing a lot of additional auxiliaries for the frictional brake, and easy for control. By simultaneously controlling the MR fluid thickness and the electric current, a large range of brake torque is achieved without increasing the radial envelop for the brake, and saturation conditions in one controller are compensated for by the other controller. High angular velocities of the brake are primarily controlled by increasing the MR fluid thickness, while low angular velocities are primarily controlled by increasing the electric current. Good transient responses for regulating a constant speed (high, moderate, and low), and good stability while seeking to track a sinusoidal input have been achieved. In summary, the proposed control system for the MR fluid brake has demonstrated good controllability for the MR fluid brake.Includes bibliographical reference
A Framework for Life Cycle Cost Estimation of a Product Family at the Early Stage of Product Development
A cost estimation method is required to estimate the life cycle cost of a product family at the early stage of product development in order to evaluate the product family design. There are difficulties with existing cost estimation techniques in estimating the life cycle cost for a product
family at the early stage of product development. This paper proposes a framework that combines a knowledge based system and an activity based costing techniques in estimating the life cycle cost of a product family at the early stage of product development. The inputs of the framework are the product family structure and its sub function. The output of the framework is the life cycle cost of a product
family that consists of all costs at each product family level and the costs of each product life cycle
stage. The proposed framework provides a life cycle cost estimation tool for a product family at the early stage of product development using high level information as its input. The framework makes it possible to estimate the life cycle cost of various product family that use any types of product structure. It provides detailed information related to the activity and resource costs of both parts and
products that can assist the designer in analyzing the cost of the product family design. In addition, it can reduce the required amount of information and time to construct the cost estimation system
Definition and verification of a set of reusable reference architectures for hybrid vehicle development
Current
concerns
regarding
climate
change
and
energy
security
have
resulted
in
an
increasing
demand
for
low
carbon
vehicles,
including:
more
efficient
internal
combustion
engine
vehicles,
alternative
fuel
vehicles,
electric
vehicles
and
hybrid
vehicles.
Unlike
traditional
internal
combustion
engine
vehicles
and
electric
vehicles,
hybrid
vehicles
contain
a
minimum
of
two
energy
storage
systems.
These
are
required
to
deliver
power
through
a
complex
powertrain
which
must
combine
these
power
flows
electrically
or
mechanically
(or
both),
before
torque
can
be
delivered
to
the
wheel.
Three
distinct
types
of
hybrid
vehicles
exist,
series
hybrids,
parallel
hybrids
and
compound
hybrids.
Each
type
of
hybrid
presents
a
unique
engineering
challenge.
Also,
within
each
hybrid
type
there
exists
a
wide
range
of
configurations
of
components,
in
size
and
type.
The
emergence
of
this
new
family
of
hybrid
vehicles
has
necessitated
a
new
component
to
vehicle
development,
the
Vehicle
Supervisory
Controller
(VSC).
The
VSC
must
determine
and
deliver
driver
torque
demand,
dividing
the
delivery
of
that
demand
from
the
multiple
energy
storage
systems
as
a
function
of
efficiencies
and
capacities.
This
control
component
is
not
commonly
a
standalone
entity
in
traditional
internal
combustion
vehicles
and
therefore
presents
an
opportunity
to
apply
a
systems
engineering
approach
to
hybrid
vehicle
systems
and
VSC
control
system
development.
A
key
non-‐functional
requirement
in
systems
engineering
is
reusability.
A
common
method
for
maximising
system
reusability
is
a
Reference
Architecture
(RA).
This
is
an
abstraction
of
the
minimum
set
of
shared
system
features
(structure,
functions,
interactions
and
behaviour)
that
can
be
applied
to
a
number
of
similar
but
distinct
system
deployments.
It
is
argued
that
the
employment
of
RAs
in
hybrid
vehicle
development
would
reduce
VSC
development
time
and
cost.
This
Thesis
expands
this
research
to
determine
if
one
RA
is
extendable
to
all
hybrid
vehicle
types
and
combines
the
scientific
method
with
the
scenario
testing
method
to
verify
the
reusability
of
RAs
by
demonstration.
A
set
of
hypotheses
are
posed:
Can
one
RA
represent
all
hybrid
types?
If
not,
can
a
minimum
number
of
RAs
be
defined
which
represents
all
hybrid
types?
These
hypotheses
are
tested
by
a
set
of
scenarios.
The
RA
is
used
as
a
template
for
a
vehicle
deployment
(a
scenario),
which
is
then
tested
numerically,
thereby
verifying
that
the
RA
is
valid
for
this
type
of
vehicle.
This
Thesis
determines
that
two
RAs
are
required
to
represent
the
three
hybrid
vehicle
types.
One
RA
is
needed
for
series
hybrids,
and
the
second
RA
covers
parallel
and
compound
hybrids.
This
is
done
at
a
level
of
abstraction
which
is
high
enough
to
avoid
system
specific
features
but
low
enough
to
incorporate
detailed
control
functionality.
One
series
hybrid
is
deployed
using
the
series
RA
into
simulation,
hardware
and
onto
a
vehicle
for
testing.
This
verifies
that
the
series
RA
is
valid
for
this
type
of
vehicle.
The
parallel
RA
is
used
to
develop
two
sub-‐types
of
parallel
hybrids
and
one
compound
hybrid.
This
research
has
been
conducted
with
industrial
partners
who
value,
and
are
employing,
the
findings
of
this
research
in
their
hybrid
vehicle
development
programs
Acta Universitatis Sapientiae - Electrical and Mechanical Engineering
Series Electrical and Mechanical Engineering publishes original papers and surveys in various fields of Electrical and Mechanical Engineering
Power transmission systems: from traditional to magnetic gearboxes
L'abstract è presente nell'allegato / the abstract is in the attachmen
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