introduction demonstration dp
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1
Introduction demonstration DPUsing models for MT218 Mechatronics in MT
H.T. GrimmeliusAssistant professor (lecturer) Marine EngineeringDelft University of Technology
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Lecture content
• A little background• Description of hard- and software• Some theory• Goal this afternoon
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Mechatronics
• Mechatronica is de naadloze combinatie van verschillende complementaire technologieën, die op een integrale wijze met elkaar samenwerken
(Federatie Hydrauliek en Pneumatiek)
• Mechatronics is the combination of MECHAnical systems with elecTRONics and informatICS
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Mechatronics
• Main components:• The actual system or process• Actuators to move or exert a force• Sensors to measure actual state• Controls to maintain required state or change
state
• Additionally required: data acquisition system
Mechatronics
•Measurements•Network theory•Digital signal-processing
•Filtering
•Digital real-time control
•Mechanics•Dynamics•Hydro
•Sensors•Actuators
project
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Available hard- & software
• System: model ship• Actuators: propulsors and servo’s• Sensors: position (x-y), heading and shaft
speeds• Controls: Simulink based system for “weather
vaning”• Data acquisition through PC
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Available hard- & software
• “COTS” equipment:• Model: standard kit• Actuators: all motors, speed controls and
servo’s• Communication: PC with standard I/O board
• Not “COTS”:• Sensors: developed for this application• Controls: Simulink based programme with
GUI
Commercial Of The Shelf
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• Wished:• Several possibilities for Weather vaning DP• Affordable and maintainable
• Implementation:• Two azimuthing thrusters (4 degrees of freedom)• Bow thruster (1 degree of freedom)• COTS• Controlled with PW signal
Actuators
t [ms]
U [V
]
10 2012
max min
~0
~5
t [ms]
U [V
]
10 2012
max min
~0
~5
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Location sensor
• Wished:• Affordable location sensor• Clear & simple working principle• Suitable to be used in towing tank
• Implementation:• Telescopic rod with angular (SITW: Stiff Inverted Taut Wire)
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Speed sensor
• Wished:• Shaft speed feedback of both thrusters• Clear & simple working principle• Accurate also at low rpm
• Implementation• Optical pick-up• Disc with 15 holes• Signal conversion (pulse DC)
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Communications
• Wished:• Continuous• Possibility for high resolution• Everything from within Matlab/Simulink• Good support
• Implementation:• Real time I/O card MF614 by HumoSoft• Digital: 8 in/8 out; analogue 8 in/4 out + 4 PWM
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Control system
• DP control• Only X-Y position controlled, heading is free• Two decoupled PID controllers with anti-wind
up
• Other controllers• Shaft speed controllers• Very suitable for application of Ziegler &
Nichols
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• Simulink models generated automatically• Three working environments
• On-line for actual sailing (closed loop)• On-line for testing harware (open loop)• Off-line simulation environment
Control system
• Graphical user interface within Matlab
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Control system: on-line
Controller Power configuration
Positiontransformation
Position error
Required
forced
Actuator
settings
Position data
Real-timeoutput
PWMsignals
Real-timeinput
Measured
voltages
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Control system: on-line testing
• On-line testing gives the possibility to directly control the actuators and read the sensor signals
Actuator
settings
Position data
Real-timeoutput
PWMsignals
Real-timeinput
Measured
voltages
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Control system: off-line
• For off-line simulation all hardware should be available in software modulesController Power
configurationPosition
transformation
Position error
Required
forced
Actuator
settings
Position data
Simulatedactuators
Simulatedship
Simulatedsensors
ForcesPosition
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Possible configurations
One thruster, full control Combined
Two thrusters, fixed relative angle
Combined
First thruster forward, second thruster lateral
First Second
One thruster forward, bow thruster
thruster
Bow thruste
r
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Education
• Two deliverables• Test: does it work• Report: why did it work
• Student reaction‘Thought we could do full DP, but problems
were already big enough now ...’
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Research projects
• thruster interaction: angles• thruster interaction: rpm• thruster – hull interaction
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Demonstration & publicity
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Manoeuvring & wind modelling
• Manoeuvring modelling• Wind modelling
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Equations of motion
pqIIrINrpIIqIMqrIIpIK
qupwwmZpwruvmY
rvqwumX
yyxxzz
xxzzyy
zzyyxx
)()()(
)()()(
Body with 6 degrees of freedom
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Reducing degrees of freedomAssumptions• no waves• no change in total mass during manoeuvre• no change in distribution of mass during manoeuvre• rotation around y-axis does not influence motion in
x-y plane
rIMruvmYrvumX
zz
)()( only forces and moments
in the x-y plane influence manoeuvring behaviour
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Hull forces
• Forces depend on:• Speed of the ship through the water• Rate at which this velocity changes• Shape of the hull• Characteristic of the water
• No confinements present (deep water, open sea)
• No waves( , , , , , )HULLF f u v r u v r
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Hull forces
• From Taylor expansion to the third power:
• Which leads for X to:
2 212!
3 2 2 313!
( , ) ( , ) [ ( , ) ( , )][( ) ( , ) 2 ( , ) ( ) ( , )][( ) ( , ) 3( ) ( , ) 3( ) ( , ) ( ) ( , )] ...
x y
xx xy yy
xxx xxy yyx yyy
f x x y y f x y x f x y y f x y
x f x y x y f x y y f x y
x f x y x y f x y y x f x y y f x y
02 2 21
2!3 3 3 2 21
3!2
[ ][ ... 2 2 ... 2 ][ ... 3 3 ..3 6 6 ... 6
hull u v r u v r
uu vv rr uv ur vr
uuu vvv rrr uuv uur
rrv uvr uvu uvr
X X X u X v X r X u X v X rX u X v X r X uv X ur X vrX u X v X r X u v X u rX r v X uvr X uvu X
]uvr
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Hull forces
• Simplification by Inoue( ) ( )hull x y vrX m u m X vr X u
22 ( ' ' ' ' ' ' ' ' ' ' ' ' ')hull y x v r v v v r r rY m v m ur LTU Y v Y r Y v v Y v r Y r r
2 22 ( ' ' ' ' ' ' ' ' ' ' ' ' ' ' ')hull zz v r vvr vrr r rN J r LTU N v N r N v v r N v r r N r r
212
212
2 212
2 2
'
'
'
XXLTUYYLTUNNLTU
U u v
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Hull forces
• Coefficients estimated based on L, B, T and cB
2
3 2
' 4' 1.42' 0.435 1.7 (1 )
' 0.472 (1 )'' 0.54
' 25.34 4.66 0.44 0.098
' 0.44 0.065
' 34197
r
bb
br b
rr b
r
b b brr
brr
br
Y k
C BY kL
TY CB
TY CB
N kN k k
B C B C B CNL L L
C TNBB CN
L
4 3 2
18941 3909 353.8 11.9b b bB C B C B CL L L
gyrrk
L
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Hull forces
• Other parameters to be estimated• Hydrodynamic mass in x and y direction• Hydrodynamic mass moment of inertia I• Straight line resistance
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Hull forces
• For low Fr and large β:• No longer valid
because of Munk’smoment
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Wind forces
• Calculated with wind speed only (ship speed very low)
2
2
2
( ) 2( ) 2( ) 2
wind X wind lat wind
wind Y wind front wind
wind N wind lat wind
X C A U
Y C A U
N C A L U
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Source of constants
• Brix:• Semi emperical
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AD converter
time
ampl
itude
time
ampl
itude
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AD converter: resolution
• Number of values = 2bits
• 8 bits: 256 levels• 10 bits: 1024 levels• 12 bits: 4096 levels
• Error1 Full Scale2b
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Aliasing
time
amplitude
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Anti-aliasing
• Sample at at least twice the highest frequency• Filter out high frequency components before
sampling
• Highest frequency: closed loop gain > 3 dB• Use bode plot!
• Rule of thumb: 2 to 4 samples during rise time of step response
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High frequency aliasing
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DA converter
-
+
U 1
Uo = ?
R2
R1
R1U 2
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DA converter
01 01 01 01 01 01 01 01
B7 B6 B5 B4 B3 B2 B1 B0
Ub
-+
Rt
Uu1K 2K 4K 8K 16K 32K 64K 128K
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Goal of today
• Checkout system• Set controller variables• Check results
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