slides in pdf

Transcript

slides in pdf

Dipartimento di
Elettronica e
Informazione
Applicazioni elettroottiche dedicate per l'industria
Michele Norgia
Sommario
• Misure di vibrazioni:
• vibrometro selmix per bilanciatura
• vibrometro a triangolazione per saldatori a ultrasuoni
• Misure biomedicali:
• misuratore di flusso di sangue (self-mixing)
• misuratore del flusso di flebo a infusione
• Misure meccaniche:
• misura del flusso waterjet a 900 m/s
• sensore per molatura di turbine (in funzione presso Ansaldo-ENergia)
•Applicazioni di largo consumo:
• triangolatore dedicato per misura dell'angolo di rollio di moto (testato da
Ducati in moto-GP)
• chitarra laser (con sensori multipli di distanza a triangolazione)
Dipartimento di Elettronica e Informazione
PROGETTO E REALIZZAZIONE DI UN
VIBROMETRO LASER
A LARGA BANDA
Interferometria a self mixing
S0
Sm
PD
Sorgente
Laser, E0
Er
s(t)
Iph
Fattore di retroiniezione:
Potenza emessa dal laser:
F(Φ) funzione di
periodo 2π
Interferometria a self mixing
0<C≤0.1
retroiniezione
molto debole
AdÆogni
salto di
0.1<C<1
Æ retroiniezione
frangia
corrisponde debole
1<C<4.6
Æ retroiniezione
uno spostamento
del moderata
C>4.6bersaglio
Æ retroiniezione
pari a λ/2forte
Segnale di comando del bersaglio
C=0.01
C=0.7
C=3
Principio di funzionamento
• Aggancio a metà frangia
•
•
•
•
Trasduzione lineare del
segnale utilizzando la
pendenza della frangia
Massima dinamica ±λ/4
Pendenza lineare: almeno
moderata retroiniezione
(C>1)
Necessità di un anello di
retroazione per operare
l’aggancio
Principio di funzionamento
Circuito vibrometro
Vout
Circuito di alimentazione
laser
Stadio adel
transimpedenza
• Retroazione interna
per controllo
• Guadagno:
Z=10potenza
kΩ
• Trimmer per regolazione
la potenza
• Adattamento
in AC
Circuito vibrometro
Circuito di compensazione
Ramo chiusura
anello
di controllo
• fp=71.9
kHz regolabile
• Trimmerin
perAC
regolazione guadagno e polo fp
• Accoppiamento
• Alimentato tra massa e +5 V
• Trimmer per regolazione valore @Lf del Gloop
Comportamento in frequenza
Indipendenza, ad alta
frequenza, della
sensibilità OUT1/Δs
dalla distanza s0
s0= 50 cm
s0= 5 cm
s0= 1 m
Realizzazione vibrometro
• 31 mm x 42 mm
MISURATORE DI VIBRAZIONI PER
SALDATORI A ULTRASUONI
Ultrasonic welding
Welding method particularly
suited for non ferrous metals
(aluminum)
The two elements are
compressed and then relatively
moved at ultrasonic frequency
Advantages:
Low working temperature
(∼50% of the fusion temperature)
Minimum energy consumption
13
Vibration Normal force
materials
Ultrasonic welder under test
Welder model “Albatros 20” by STAPLA Ultrasonic
Piezo‐actuator, booster and sonostrode
Piezo-actuator
Sonotrode
Nodes
Anti-nodes
• Oscillation frequency: 20 kHz
• Maximum vibration p‐p amplitude: 50 μm
14
System requirements
15
The required instrument should measure istantaneous
vibration amplitude and frequency, in order to control the correct welder working
• High bandwidth (B > 100 kHz)
• High resolution (Δx < 1 µm)
• Low measurement range (∼1 mm)
• Low cost (< 100 $)
• Compactness (few cm)
Measurement technique
Interferometry
16
A custom‐made low‐cost self mixing interferometer has been s
developed
LASER
MONITOR PD
REMOTE
TARGET
Very difficult to develop a low-cost
acquisition and elaboration system
Interferometric signal
Reconstructed displacement
Optical triangulator – working principle
17
The target distance L is measured by the position x of the spot on the photodetector :
L
Laser
ΔL
A
D
Target
frec
B
x
Δx
Photodetector:
PSD or linear CCD
Optical triangulator - PSD
18
PSD (Position Sensitive Detector)
Made by a photodiode with two anode contacts and high resistance.
Low-cost analog device, with a good linearity.
Optical beam
Ir
L
x
Il
Iph
The two photo-generated currents
depend on the optical spot position
Optical triangulator - Project
19
Problems:
•
Typical triangulator are pulsed (few kHz), in order to cancel
ambient light contribution (by a high-pass filtering)
Difficult to find 100 kHz bandwidth
•
Resolution Δx < 1 µm
•
Low cost (< 100 $)
Solutions:
•
No need for pulsed modulation: the signal itself is at high
frequency (20 kHz)
Easy to reach 100 kHz bandwidth
•
Custom geometrical project
•
Analog elaboration and a simple low-frequency microcontroller
Optical triangulator – Block Scheme
20
PSD
Double
Trans‐impedance
amplifier
Sum and difference
circuits
Analog
divider
LED indicators
HP filter
Microcontroller
Peak measurement
Display Analog
output
Optical triangulator – First prototype
21
Optical triangulator – Characterization
22
Static characterization: good linearity over a range ±0.5 mm Vout [V]
y = 0,0117x
0,4
0,347
0,3
0,287
Sensitivity
0,230
0,2
0,174
0,115
0,1
0,065
0,0
-35
-30
-25
-20
-15
-10
-5
-0,004
0
-0,071
-0,113
-0,1
5
10
15
20
30
35
Spostamento [ μm]
Displacement
-0,168
-0,2
-0,243
-0,301
25
-0,3
-0,355
-0,4
Resolution
Δx ≅ 0.5 µm
Measurement results
Vibration measurement
23
Pre‐burst time
Sonotrode
separation
40
20
-20
-40
-60
-80
5
-100
0
-120
0
0.5
1
1.5
Time [s]
Amplitude [μm]
Amplitude [μm]
0
Sonotrode fall
-5
-10
2
2.5
-15
-20
-25
-30
1.0499
1.05
1.0501 1.0502 1.0503 1.0504
Time [s]
Measurement results
Example of non-correct welding
Amplitude decreased during the welding process
24
Conclusions
25
• The realized optical triangulator has demonstrated the requested performances:
• High bandwidth (B = 150 kHz)
• High resolution (Δx ≅ 1 µm)
• 1 mm measurement range
• Low cost (about 50 $)
• Compactness (few cm)
• Available outputs : • display (frequency and amplitude)
• Analog displacement
• Serial communication (RS‐232)
Future development:
• Realization of an engineered instrument
• Application of the instrument for the real‐time welder control
Dipartimento di
Elettronica e
Informazione
Optical Flowmeter for Blood
Extracorporeal Circulators
Michele Norgia, Alessandro Pesatori : Politecnico of Milano
Luigi Rovati: University of Modena and Reggio Emilia
Objectives
•
Laser based sensor
•
Low cost
•
Simple implementation
•
Good accuracy (∼2%)
•
Wide range of measurement (till to 0.4 m/s)
•
Measurements of velocities in different
media (blood, water, milk, etc…)
State of art
4/18
Doppler effect based sensors (ultrasonic sensors)
Sensible to thermal dilatation
and vibration
Mechanical mounting
complexity
Time of flight based sensors (ultrasonic sensors)
Tube must be always filled of
fluid
Not always good accuracy
High cost of calibration for
different media
Measurement principle
8/18
Self-mixing interferometry:
Doppler shift for displacement in laser direction.
Interferometric signal shows this behavoiur:
s(t) = sin(2kvt)
2ks = 2π
2 (2π/λ) (v sin(α)) = 2πf
Interferences fringes
λ
1
v =f ⋅ ⋅
2 sin(α )
Flow = v × Area
Setup design
9/18
Self-mixing interferometer setup:
LENS 1
f = 8 mm
MONITOR
PHOTODIODE
LENS 2
f = 8 mm
α
LASER
DIODE
8 mm
flux
8 mm
Laser and
photodiode
Electronic scheme
Two lenses
focalization setup
vm = vf × sin(α)
Transimpedance
amplifier
Setup design
peristaltic pump
(max v = 45 cm/s)
10/18
intralipid filled tube
interferometer
Experimental results
11/18
Spectra measurements acquired for fluid (Intralipid)
at different velocities (α = 25°)
-35
stop
11 cm/s
17.5 cm/s
21 cm/s
31.5 cm/s
37.5 cm/s
45 cm/s
-40
Amplitude [dBm]
-45
-50
-55
-60
-65
-70
-75
0
200
400
600
800
Frequency [kHz]
1000
1200
Setup design
Doppler spectrum → PDF of the velocity distribution
∞
∫ p( f ) fdf ∑S( f ) f
f=
≅
∑S( f )
p
(
f
)
df
∫
0
∞
0
Implementation of weighted filters:
Photodiode
signal
High pass
Low pass
Band pass
Band pass
-
Bank of filters
10 kHz
80 kHz
180 kHz
400 kHz
Estimated
frequency
Flow
calculation
Experimental results
16/18
Measured velocities on Intralipid with weighted analog filters
50
45
A1 ⋅V12 ⋅ f1 + A2 ⋅V22 ⋅ f 2 + A3 ⋅V32 ⋅ f3 + A4 ⋅V42 ⋅ f 4
f =
V12 +V22 +V32 +V42
Measured Velocity [cm/s]
40
35
30
25
λ
1
v =f ⋅ ⋅
2 sin(α )
20
15
10
10
15
20
25
30
35
Real Velocity [cm/s]
40
45
50
A1, A2, A3, A4 parameters calculated after calibration
Conclusions
18/18
Conclusions
•An optical flowmeter was designed and realized and
experimentally tested
•The instrument is capable of measure every type of liquid
calibrating weighting values
•Accuracy of measurement of 2% over a dynamic of
measurement till 0.4 m/s
•Very low cost implementation
Future development
•Analog filters and velocity calculation will be implemented digitally in a
DSP system with bubble detection feature
MISURATORE VOLUMETRICO
PER FLEBOCLISI
Tesi di Laurea di
Simone SUARIA
matr. 708556
Tecniche di infusione
•
•
Sistemi di pompaggio
Infusione per gravità
morsetto
diversità delle gocce
• velocità, temperatura, viscosità, peso
specifico
Sistema di infusione che coniughi semplicità di
regolazione, costi contenuti ed elevata precisione.
Stima del volume: analisi teorica
variazione intensità
luminosa
raggio del cilindro
velocità di caduta
altezza del cilindro
Sistema di lenti
Singolo fascio, due barriere luminose
barriera meccanica sui fotodiodi
Circuito di rilevazione
fHPF = 200 Hz
GOPA = 4
Tensioni rilevate
2.4
2.2
tensione (V)
2
1.8
1.6
1.4
ΔT
1.2
0
5
OUT 1
OUT 2
10
15
tempo (ms)
20
25
Oscuramento
7
raggio della goccia (mm)
6
5
4
3
2
1
0
oscuramento percentuale
0
0.1
0.2
0.3
0.4
0.5
0.6
oscuramento percentuale
r = f(oscuramento%)
0.7
0.8
0.9
1
Stima della velocita’
• Prima stima: goccia ~ corpo rigido
1
25
0.95
Stima del volume
0.9
0.85
Velocità media su cui effettuare integrazione
20
s (mm)
15
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
10 0.35
0.3
0.25
0.2
5 0.15
0.1
Stima della velocità
0.05
0
0
0
V reale
V misurata
Appr. lineare
0
0.05
0.1
0.01
0.15
0.2
0.25
0.3
0.02
0.35
0.4
0.45 0.5
0.55 0.6
Velocità misurata (m/s)
0.03
0.04
0.65
dipendenza da lG
t(s)
0.7
0.75
0.05
0.8
0.85
0.9
0.06
0.95
1
0.07
Stima della velocita’
• Seconda stima: goccia ~ particelle scorrelate
v[0] = vmis
v[i] = vmis + gt[i]
• Algoritmo implementato
v’[i] = v[i] • C
C = 0.6 ~ 0.8
h[i] = v’[i] • dt
Programma LabVIEW
Prototipo realizzato e taratura
CT = 0.94
Distribuzione misure 1ml
30
frequenza di ripetizione
25
μ1 = 1.01 ml
σ1 = 0.04 ml
N = 100
20
15
10
5
0
0.8
0.85
0.9
0.95
1
volume stimato (ml)
CT‘ = 0.93
1.05
1.1
1.15
1.2
Distribuzione misure 2 ml
20
18
μ2 = 2.00 ml
σ2 = 0.05 ml
N = 50
16
frequenza di ripetizione
14
12
10
8
6
4
2
0
1.9
1.95
2
volume stimato (ml)
2.05
limite urel = 1% per V > 10 ml
2.1
Conclusioni
• Principio di funzionamento semplice
• Rispettate le specifiche di progetto
Accuratezza minore 5%
Costo contenuto: circa 5 €
• Ipotizzato funzionamento con gocciolatore in plastica
lo strumento di misura realizzato è in grado di
competere, in termini di prestazioni e accuratezza,
con gli strumenti di infusione farmacologica
attualmente presenti sul mercato.
MISURAZIONE DI VELOCITÀ DI APPARATI WATERJET MEDIANTE TECNICHE DI LASER DOPPLER VELOCIMETRY
L’IMPIANTO DI TAGLIO WATERJET
TRAMOGGIA
ABRASIVO
ACCUMULATORE
INTENSIFICATORE
TESTA DI TAGLIO
TRATTAMENTO ACQUA
Componenti principali:
WATERJET: Tecnologia
che permette tramite
getto ad alta velocità il
taglio e la lavorazione di
diverse
tipologie
di
materiali.

Impianto di trattamento dell’acqua
Sistema di intensificazione della pressione
Accumulatore
Tubazioni dell’alta pressione
Testa di taglio
Sistema di adduzione dell’abrasivo
IL SISTEMA DI MISURA LASER DOPPLER VELOCIMETRY
Parametri costanti:
Distanza getto d’acqua - beamsplitter L
Distanza specchio - beamsplitter s
Lunghezza d’onda del laser λ

Componenti del sistema di misura Laser Doppler Velocimetry:

FotodiodoeGPIB
Interfaccia
Oscilloscopio
Lente
- USB - B
Specchio
Laser
beamsplitter
Frange: piani orizzontali
luogo dei punti in cui i due
fasci si sommano tra loro
con interferenza costruttiva.
λ⋅L
f ⋅D
6
velocità del
d’acqua
vale: V = D vale:
D
≅
⋅
10
= 0,05 mm
[
m/s
]
La distanza
tra getto
le frange
d’interferenza
−3
s
10
dove:
dove:
D = distanza tra le frange [mm]
nota
λ = 787,5 nm lunghezza d’onda laser
f = frequenza di attraversamento delle frange [MHz]
acquisita
L = 2250 mm distanza getto - beamsplitter
s = 35 mm distanza specchio - beamsplitter
LE PARTICELLE DI SCATTER ED IL SEGNALE ACQUISITO
Generazione del segnale affidata al
fenomeno
di scattering (formazione di
• In frequenza,
qualora
un su muovano
segnale
luminoso)
le particelle
’attraversamento
delle frange.
tutte a all
velocit
à v, il
• Il singolo
profilo
del segnale
segnale siè
presenta
come un
ancora
gaussiano
seno modulato da una
•gaussiana
La risoluzione migliora
con il numero delle
• Il attraversate
segnale
frange
complessivo
è
la
•somma
Particelledeicentrali
le
singoli
pi
ù idonee acongenerare
sommati
fasi
un
buon segnale
casuali
CIRCUITI ELETTRONICI PER LA FOTORIVELAZIONE
Il segnale in uscita
transimpedenza:
dal
• Necessita di amplificazione
in quanto troppo debole per
essere
elaborato
correttamente
• Richiede un filtraggio per
impedire al rumore a bassa
frequenza di divergere
56
ANALISI DELLE MISURE SPERIMENTALI
Obiettivi:
RICERCA DELLA
CURVA MATEMATICA
CHE DESCRIVE
I DATI SPERIMENTALI
(fitting)
CONFRONTO FRA LE
CURVE DI REGRESSIONE
CON E SENZA FILTRAGGIO
57
Curva di regressione Lorentziana su ugello SP
•
•
•
A
pressione
minima
(100MPa) la distribuzione
Lorentziana ben si addice
ai risultati della misura
Simmetria nell’intorno del
picco
Valida
approssimazione
cilindrica del getto
Minima dispersione delle
particelle
d’acqua
più
esterne per attrito con l’aria
SPECIAL 15mm 100MPa
-60
-70
-80
Amplitude [dB]
•
-90
-100
-110
-120
5
10
15
Frequency [Mhz]
20
58
25
Curva di regressione Gaussiana su ugello SP
•
•
Allargamento Gaussiano
dovuto alla strumentazione
elettronica
di
misura
(attraversamento di un
numero limitato di frange)
Curva Gaussiana segue i
dati
sperimentali
solo
nell’intorno del picco
Allargamento Lorentziano
proprio
del
sistema
WaterJet
SPECIAL 15mm 100MPa - Gaussian Fitting
-60
-65
-70
-75
Amplitude [dB]
•
-80
-85
-90
-95
-100
-105
-110
-115
2
4
6
8
10
12
Frequency [Mhz]
14
59
16
18
20
MISURA CON WEBCAM DELLA DISTANZA FRA LE FRANGE
Risultati dell’analisi con webcam
•
•
Grafico
dell’andamento
dell’intensità luminosa su
una
linea
verticale
dell’immagine
Il programma cerca le
frequenze di interesse, ne
fa la trasformata ed estrae
il valore più ripetuto
Infine tramite trigonometria
si risale alla distanza
cercata (51μm)
FFT didiuna
intensità
unariga
rigaverticale
verticale
180
7000
160
6000
140
intensità
luminosa
modulo intensità
•
5000
120
4000
100
3000
80
2000
60
1000
40 0
00
50
100
0.005 150
200
300
0.01 250 0.015
n°
pixel
frequenza spaziale
350
400
0.02
450 0.025
500
CONCLUSIONI E SVILUPPI FUTURI
Conclusioni
•
•
•
•
Il sistema produce risultati
ripetibili e stabili
Il sistema presenta una
buona riproducibilità delle
misure
Incertezza teorica molto
piccola
Velocità ricavata inferiore a
quella teorica sebbene ne
rispecchi l’andamento
Prospettive future
Sistema robusto e stabile ma
ulteriori
migliorie
potrebbero
coinvolgere:
• Il sistema di generazione dei
fasci (utilizzo di laser più potenti)
• Una elettronica di ricezione più
sensibile
Tuttora in svolgimento lo studio
teorico
delle
analogie
fra
allargamento Lorentziano della
distribuzione di velocità e natura
61
fisica del getto
62
Dipartimento di
Elettronica e
Informazione
Optical Instrument for Real Time Monitoring
of Steam Turbine Grinding
Alessandro Pesatori
Michele Norgia
Cesare Svelto
STEAM TURBINE
Numeric
control
Palette radial length
measurement
Mechanical
translator
Grinder
Length 13 m
Diameter 4 m
turbogas
turbine
OBJECTIVES
Measurements requirements from Ansaldo ENergia:
• Relatively quick measurement
• Real-time measurement during grinding process
•Different shape and material palette measurement
• Measurement accuracy of 20 μm
• High repeatability
• Allowing measurement while turbine rotating at
10 round/min
Measurement technique choice
laser
optical beam
mechanical
translator
turbine
electronic
interface
palette
four quadrant
photodiode
System block diagram
worker
Working principles
Palette
Sout (V)
Optical barrier
direction of
work
Minimum
uncertainty
point
Four qudrant photodiode
Position (µm)
costant
Mechanical project
Mechanical
structure
realized
OBJECTIVES
• Mechanical requirements:
• High stiffness structure
Precision mechanical
translator
• Aerodynamic and not
vibrating due to palette
rotation
• Weight inferior to 2,5 kg
Measurement
system
• Compatibility with precision
mechanical translator
Feeler pin
Electronic project
Readout electronic from four quadrant photodiode
Laser diode
Trans-impedance
Four quadrant
photodiode
Circuit realized
Electronic project
Electronic elaboration
manage
four quadrant signal
and
activate
the
mechanical arm stop
command in turbine
machine PLC
Back panel of
electronic
elaboration that
interface
SAFOP PLC
+
AL
4PD
IN
-
Diagnostic
OUT
+
SP
-
WAR
+
-
LEV
+
-
/LEV
+
-
CAB
+
-
SYNC
+
-
POWER MAX 10W
Line voltage range
AC 220-240 ~
Preliminary results
System transfer function and error
Accuracy lower then 2 µm over 50 µm
(estimated over 100 points for measurement)
Results at Ansaldo
Results at Ansaldo
Measurements done real-time at Ansaldo ENergia
1.1
200
0
0.8
-200
0.7
0.6
0
-50
displacement (um)
0.9
displacement (um)
voltage (V)
1
-400
-600
0.5
-100
-150
-200
1.08
1.09
-800
1.1
1.11
1.12
1.13
1.14
1.15
1.16
1.17
1.18
time (min)
-250
-1000
0
0.5 1.06
1.07 1
1.08
1.09
1.11
1.5 1.1
2
time (min)
time (min)
1.12
1.13
2.5
1.14
Results at Ansaldo
Conclusions
•An optical barrier was designed and realized
For palette radial measurement
•The instrument is capable of measure every type
(shape and material) palette
•Accuracy of measurement of 10 μm over a range of
450 μm dominated by mechanical arm error
•Repeatability of 5 μm
Future development
An automated system through Pc will be realized in
order to obtain a more accurate control of process
Dipartimento di
Elettronica e
Informazione
Characterization of Optical Sensors for Real-Time
Measurement of Motorcycle Tilt Angles
Michele Norgia
Cesare Svelto
Ivo Boniolo
Mara Tanelli
Sergio Savaresi
Motorcycle attitude
roll-pitch-yaw angles
77
In a motorcycle, the attitude is
described referring to a
moving frame centred in the
vehicle center of mass G.
The attitude of the vehicle is represented by the roll-pitchyaw angles:
•the roll angle φ measures the rotation around the x axis
•the pitch angle θ that around the y axis
•the yaw angle ψ that around the z axis
Measurement system
78
Roll and pitch angle measurement by distance measurement - 1
PITCH
Measurement
points
ROLL
Three measurement
points are enough for
calculating the roll
and pitch angles
Measurement system
79
Roll and pitch angle measurement by distance measurement - 2
θ Y
φ
d1 = H 0 + L/ 2 ⋅ tan (ϕ )
X
d 2 = H 0 − L/ 2 ⋅ tan (ϕ )
⎛ d1 − d 2 ⎞
ϕ = arctan ⎜
⎟
⎝ L ⎠
Measurement system
Low-cost optical triangulator - 1
For this specific application,
the best solution seems to be
an optical triangulator, also
available at very low cost.
80
Linear CCD or PSD
A
B
TARGET
• Very small
• Low cost
• Low weight: <10 g
• Variable range depending
on the mounting conditions
• Not-high performances
B
A
OPTICAL SOURCE
Measurement system
Low-cost optical triangulator - 2
Static calibration curve
To avoid ambient light
disturbances, the optical
source is pulsed at 1 kHz
10% duty cycle
Δd ≅ 1 mm
Output Voltage [V]
81
Δd ≅ 1 cm
Target Distance [cm]
•
•
•
•
•
•
•
Vin: 5 V
Iin: 30 mA
Vout: 0.5 – 2.8 V
Range: 5 – 80 cm
Resolution 20 mV
Delay time: 40 ms
Poptical: 0.5 mW average
Measurement system
Measurement accuracy
82
The mounting parameters H0 and L should be determined so to
minimize the uncertainty in the measurement.
Andamento
incertezza
di rollio con parametri
ottimi
Roll
angle
accuracy
< 1°
Pitch
angle
< 0.2°
Andamento
incertezza accuracy
di beccheggio con parametri
ottimi
0.2
0.18
0.8
Pitch uncertainty [°]
Roll uncertainty [°]
1
0.6
0.4
0.2
60
0.16
0.14
0.12
0.1
0.08
60
10
40
5
20
Roll angle [°]
-5
5
20
0
0
10
40
Pitch angle [°]
Roll angle [°]
0
0
-5
Pitch angle [°]
Trial sessions
Sensors mounting
83
Sensors with range 5-50cm
under the keel
Sensors with range 12-100 cm
Trial sessions
Acquired signals
84
• Some problems appear at high motorcycle speed with solar lighting.
• A significant optical interference phenomenon exists, due to a
combination of high vehicle speed and strong solar lighting, but also
depending on the asphalt roughness.
30
Solar ligth - 10 km/h
0
5
10
15
20
Time [s]
25
30
30
35
40
Distance [cm]
20
10
Shadow - 70 km/h
25
20
15
10
20
10
0
5
10
Time [s]
15
20
35
0
5
10
15
20
Time [s]
25
30
30
35
40
Solar ligth - 70 km/h
20
10
Solar ligth - High roughness - 70 km/h
30
Distance [cm]
Distance [cm]
Distance [cm]
Distance [cm]
35
0
5
10
15
20
Time [s]
25
30
35
40
Solar ligth - Low roughness - 70 km/h
30
25
20
15
10
0
5
10
Time [s]
15
20
Trial sessions
Asphalt roughness measurement
85
Asphalt profilometry measured by means of a high precision optical
laser sensor, in a test carried out at constant vehicle speed v=3 km/h
1
20
high frequency
optical disturbances
15
10
0.5
1
0
10
20
25
Time [s]
50
0
40
1 km/h
0.5
0
0
500
1000
1500
Frequency [Hz]
2000
2500
PSD
magnitude
1
30
-0.5
20
10
0
5
10
15
15
20
25
30
Horizontal distance [cm]
20
35
40
15 km/h
0.5
0
25
Time [s]
0
500
1000
1500
Frequency [Hz]
2000
2500
1
PSD
magnitude
Distance [cm]
15
PSD
magnitude
5
Roughness [cm]
Speed [km/h]
25
50 km/h
0.5
0
0
500
1000
1500
Frequency [Hz]
2000
2500
Low-cost optical solution
86
PROBLEM SOLUTION:
increase signal-to-noise ratio, without increasing cost and complexity
•LASER emitter
(in substitution to the LED, directly supplied by a current shunt)
• → signal power increased of a factor 50
•Optical low-cost plastic filter (attenuating visible light)
• → disturb power divided by a factor 5
Measurement system
Block scheme of the elaboration algorithm
Distance
OUTLIERS
ELIMINATION
Voltage
measured
(RAW)
Non linear
filtering
Data processing for
spikes avoiding
87
Attitude
Angle
Distance
FILTERED
Linear
filtering
15 Hz filtering stage
for noise reduction
Attitude
angles
measurement
Computation of the
roll angle
Measurements on urban road
Algorithm test
88
40
Roll angle - RAW
Roll angle - NL FILTER
Roll- angle
- RAW
Roll angle
L FILTER
Roll angle - NL FILTER
Roll angle - L FILTER
40
30
30
20
20
10
0
A ngle [°]
Angle [°]
10
0
-10
-10
-20
-20
-30
-40
-30
0
20
-40
0
40
5
60
80
10
100
15
Time [s]
120
20
Time [s]
140
25
160
30
180
35
200
40
Measurement on a racetrack (Misano, Italy)
Reconstruction of one lap
89
The signal on the racetrack asphalt is very good,
even for speed of 300 km/h!
Curve number
1
3
4
8
9
10 11
60
Roll Angle
40
8
6
5
20
9
7
Angle [°]
4
13
3
2
12
1
6
0
-20
10
-40
11
-60
0
10
2
20
30
5
40
7
50
60
Time [s]
70
80
90
100
12 13
110
Measurement on a racetrack (Misano, Italy)
Reconstruction of seven laps
90
60
Giro 1
Giro 2
Giro 3
Giro 4
Giro 5
Giro 6
Giro 7
40
Angle [°]
20
0
-20
-40
-60
0
10
20
30
40
50
60
Time [s]
70
80
90
100
110
Measurement on a racetrack (Qatar)
Reconstruction of ten laps
91
The wear and tear on tires (at the last laps)
80
60
40
Angle [°]
20
0
-20
-40
-60
-80
40
60
80
100
Time [s]
120
140
160
92
93
Dipartimento di
Elettronica e
Informazione
Optical Instrument for Real-Time
Guitar Measurements
Michele Norgia
Measuring the fingers position
95
Optical triangulator – working principle
96
The target distance L is measured by the position x of the
spot on the photodetector :
L
Laser
ΔL
A
D
Target
frec
B
x
Δx
Photodetector:
PSD
Evaluation of a single triangulator range
97
as a function of the distance between the laser and the PSD
The distance range is calculated by the Signal to Noise ratio and the geometry, in
order to reach a resolution of 1 mm (blue), 2 mm (green) or 3 mm (black).
(black)
The PSD dimension is 3.5 mm.
The distance between the lens and the PSD (equal to the focal lens) is 2 or 3 cm.
The calculation is based on some assumptions on the laser power, finger reflectivity,
electronic and PSD noise, with 10 averages for each measurement (pulses freq. 60 kHz ),
considering the worst-case.
WORST-CASE CALCULATION
100
100
Focal length 2 cm
80
80
70
70
60
60
50
40
30
50
40
30
20
20
Res=1mm
Res=2mm
Res=3mm
10
0
Focal length 3 cm
90
Distance [cm]
Distance [cm]
90
1
2
3
4
5
Triangulator Arm [cm]
6
Res=1mm
Res=2mm
Res=3mm
10
7
0
1
2
3
4
5
Triangulator Arm [cm]
6
7
Design of the multiple laser-receiver system
98
4 Detectors
Position Sensing Detectors
3.5 cm
Alternatively pulsed
laser beams
3 cm
4 cm
3.5 cm
Legend: yellow - good measurement
blue – no measurement
black – not useful (triangulator arm too short)
Finger
Examples of critical cords
99
Legend:
yellow - good measurement
blue – no measurement
black – not useful (triangulator arm too short)
Test of the measurement technique
First design
Electronic reading circuit
DAQ card
Electronic supply
100
Electronic circuits
Laser pulsed supply
101
Data Acquisition: LabVIEW program
102
Calibration coefficients
Acquired signals:
Sum and Difference
Calculated
Finger Distance
Proof of concept:
mechanical realization
103
lens
LASER
Proof of concept:
performance characterization on the guitar
104
70
Analytical model:
D=
Distance [cm]
60
1
c1 + c2 S + c3 S 2 + c4 S 3
50
40
30
D = finger distance
20
-0.8
S = PSD output
2
-0.6
-0.4
-0.2
0
Out PSD
0.2
0.4
0.6
0.8
Error [mm]
1
0
-1
-2
-3
20
Model error
Standard deviation
30
40
50
Distance [cm]
60
70
Proof of concept: real-time MIDI output
Distance acquired in real-time
(10 measurements/second)
converted in a MIDI output
SOUND
105
Conclusion
106
The realized proof of concept, with 1 string measurement, exhibits:
•
Resolution <1 mm
(limited by noise and disturbances)
•
Absolute accuracy <3 mm
(limited only by the mechanical stability of the first prototype)
•
Speed 10 meas./second: real-time sound

•
•
•
(limited by PC acquisition and elaboration time)
Optical laser power 0.5 mW
Laser wavelength 980 nm (infrared)
Battery operation
Final Design