QUI - TRIWU

Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
PO-FESR Sicilia 2007-2013
CUP: G13F12000020004
An Early Warning System for
Structural Monitoring
in AAL Context
Bruno Andò, Vincenzo Marletta, Antonio Pistorio
University of Catania – Italy
May 19-22, 2015
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
OUTLINE
• The Traditional Monitoring of Structures
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
• The Developed System
• Experimental Characterization of the System
• A Wavelet Multiresolution Strategy
• Results and Conclusions
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
The Traditional Monitoring of Structures (1/2)
Definitions
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Multi-Sensor System. A multi-sensor system is a system in which the
information of several sensors contribute to define the knowledge of an
environment.
EWS. An early warning system is a multifunctional system including
sensors, signal processing and communication facilities aimed to timely
provide information useful to prepare resources and response actions to
minimize the impact of the incoming hazard.
SHM. The structural health monitoring is the process to detect damage
or changes to the material and/or geometric properties of a structural
system.
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
TRADITIONAL INSTRUMENTS
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
The Traditional Monitoring of Structures (2/2)
University of Catania - Italy
Kinemetrics EpiSensor
ES-T (for acceleration
measurements)
High Costs
High Power
Supply
Applied Geomechanics
mod. 702 (for tilt
measurements)
Quanterra Q330 (for
data acquisition and
storage)
Monitoring with
Low Spatial
Resolution
An Early Warning System for Structural Monitoring in AAL Context
OUTLINE
• The Traditional Monitoring of Structures
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
• The Developed System
• Experimental Characterization of the System
• A Wavelet Multiresolution Strategy
• Results and Conclusions
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
The Developed System (1/4)
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
GOAL. Development of a customized multi-sensor node
for the implementation of a distributed EWS for SHM,
based on a wireless sensor network.
The ability to monitor simultaneously both the seismic and tilt quantities, could
be a useful tool for the risk assessment of the population.
Specifications:
 Measure and analysis of acceleration
signals, with a resolution of 0.02 g;
 Measure and analysis of tilt signals, with a
resolution of 0.004 °;
 Observation of phenomena, having
frequency range [0.5 ÷ 10] Hz;
 Sampling frequency 200 Hz;
 Data storage;
 Wireless communication.
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
The Developed System (2/4)
Surveillance
Center
Master
Node
Sensor
Node #1
…
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Sensor
Node #n
Inclinometers
Sensor
Node #2
Triaxial
Accelerometer
Wireless SD Shield
Arduino Uno
Battery
XBee-PRO
Module
Schematization of the developed system for seismic
and tilt monitoring.
University of Catania - Italy
Commercial Off-the-Shelf (COTS) devices:
 low cost;
 low-power consumption.
Arduino Uno microcontroller board (based on
the ATmega328 microcontroller running at 16
MHz).
Wireless SD Shield by Arduino (to
communicate wirelessly through the XBee-PRO
module from MaxStream and to store data on
a micro SD card).
MEMS-based accelerometer MMA7361L by
Freescale Semiconductor to measure
accelerations along the x, y and z axis.
MEMS-based inclinometers SCA61T-FAHH1G
by Murata Electronics Oy for the monitoring of
the tilt.
An Early Warning System for Structural Monitoring in AAL Context
The Developed System (3/4)
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
a
c
b
Real views of the wireless multi-sensor node (a),
the master node (b),
and a panel of the GUI with experimental results
obtained during the first assessment survey (c).
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
The Developed System (4/4)
The context adaptive architecture
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Two operating mode
Acquisition
 Continuous data transfer (extract a
deep information; more complex
infrastructures; high power
consumptions).
 Event-triggered (fast generation of
early warnings; low power
consumptions; server free operations;
limited computational power): tradeoff
between low-power consumptions and
the extraction of deep informations.
University of Catania - Italy
Storage
Transmission
Techniques
-
Continuous data transfer:
TX Real-Time Vs Server
-
Event-triggered:
Alert/Messaging, TX RealTime Vs Server if suprathreshold signals are
detected
An Early Warning System for Structural Monitoring in AAL Context
OUTLINE
• The Traditional Monitoring of Structures
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
• The Developed System
• Experimental Characterization of the System
• A Wavelet Multiresolution Strategy
• Results and Conclusions
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Experimental Characterization of the System (1/2)
The 3 axis accelerometer
Vibration
Controller
Displacemente transducer
Shaker
Shake
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Conditioning
circuit
Mobile platform
Schematization of the experimental
set-up
Acquisition
board A/D
Actuator
Power amplifier
PC for data
Acquisition
Functions
generator
Real view of the experimental
set-up
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Experimental Characterization of the System (2/2)
The 3 axis accelerometer
0.01
acceleration [g]
Comparison between acceleration signals by the
reference sensor (solid) and the wireless multisensor node (dotted):
0.015
0.005
0
-0.005
-0.01
-0.015
0
acceleration [g]
(b) with a vertical solicitations of about 0.2 g @ 5 Hz.
0.5
1
Reference sensor
Wireless multi-sensor node
(b)
0
-0.5
0.25
0.5
0.75
time [s]
(c) Frequency response of the acceleration module
embedded in the multi-sensor node.
-10
0
(c)
10
0
10
frequency [Hz]
University of Catania - Italy
0.75
0.5
-1
0
Resolution @ 1 σ level = 0.007 g
Noise floor @ 1 Hz = 0.008 g/√Hz
0.25
time [s]
1
(a) without solicitations, and
Reference sensor
Wireless multi-sensor node
(a)
gain [dB]
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Amplitude: [0.01 - 1] g
Frequency: [0.5 - 17] Hz
1
1
An Early Warning System for Structural Monitoring in AAL Context
OUTLINE
• The Traditional Monitoring of Structures
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
• The Developed System
• Experimental Characterization of the System
• A Wavelet Multiresolution Strategy
• Results and Conclusions
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
A Wavelet Multiresolution Strategy (1/4)
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
A wavelet multiresolution strategy has been adopted to discriminate the structural
response to seismic sources from other exogenous inertial components.
The processing paradigm runs in the remote server collecting data from the WSN
implementing the monitoring system.
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
A Wavelet Multiresolution Strategy (2/4)
acceleration signal used to stimulate the
wireless multi-sensor node in the vertical
direction
time-frequency image of the vertical
acceleration signal acquired with the
wireless multi-sensor node after the
application of the mechanical
solicitations
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
A Wavelet Multiresolution Strategy (3/4)
The vertical component of the acceleration
signal provided by the multisensory node has
to be decomposed in an approximation level
and several details levels using the Discrete
Wavelet Transform (DWT).
Each detail level is compared with
amplitude/frequency modes typical of the
human activity.
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
A Wavelet Multiresolution Strategy (4/4)
candidate seismic sources
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
As a further step, detail levels showing a high
correlation with the typical environment
vibrations have to be removed.
Successively, the remaining components of
the vertical acceleration signal has to be
reassembled from the residual detail levels.
The latter is expected to be really informative
on possible seismic response of the structure.
By comparing such residuals with predetermined threshold, candidates anomalous
seismic response of the structure can be
highlighted.
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
OUTLINE
• The Traditional Monitoring of Structures
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
• The Developed System
• Experimental Characterization of the System
• A Wavelet Multiresolution Strategy
• Results and Conclusions
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Results and Conclusions
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
In this work a wireless multi-sensor architecture for a distributed monitoring of seismic
and tilt data for Early Warning in Structural Monitoring has been developed.
Acceleration
Tilt
Operating range: ±1.5 g
Resolution: 0.007 g
Operating range: ±30 °
Resolution: 0.004 °
Major outcomes of the proposed methodology:
“smart dust” approach (high resolution maps of the health status of the structures with a
high number of low cost wireless multi-sensor nodes).
Future work:
test the whole system performances in real environments for a long observation time.
ACKNOWLEDGMENT
This work is developed under the project “Attività di sviluppo sperimentale
finalizzata alla riduzione del rischio sismico nella Sicilia orientale”, CUP:
G13F12000020004, funded by the PO-FESR Sicilia 2007-2013 program
University of Catania - Italy
An Early Warning System for Structural Monitoring in AAL Context
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica
Installation: Protezione Civile (ME)
09 Apr 2015, 00.04.12 (GMT)
(“Terrazzo”)
University of Catania - Italy