11 Wireless Structural Sensing and Feedback Control with Embedded Computing Yang Wang, Prof. Kincho...
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Wireless Structural Sensing and Feedback Wireless Structural Sensing and Feedback Control with Embedded ComputingControl with Embedded Computing
Yang Wang, Prof. Kincho H. Law
Department of Civil and Environmental Eng., Stanford Univ.
Andrew Swartz, Prof. Jerome P. Lynch
Department of Civil and Environmental Eng., Univ. of Michigan
Kung-Chun Lu, Prof. Chin-Hsiung Loh
Dept. of Civil Eng., National Taiwan Univ.
SPIE. San Diego, CA. Feb 27, 2006
22
OutlineOutline
Research BackgroundResearch Background
Hardware and Software Design of the Hardware and Software Design of the Wireless Structural Wireless Structural SensingSensing System System
Validation Tests: Geumdang Bridge, KoreaValidation Tests: Geumdang Bridge, KoreaLaboratory Steel Frame at NCREE, TaiwanLaboratory Steel Frame at NCREE, TaiwanGi-lu Bridge, TaiwanGi-lu Bridge, Taiwan
Hardware and Software Design of the Hardware and Software Design of the Wireless Feedback Wireless Feedback Structural ControlStructural Control System System
Half-scale Laboratory Steel Frame with MR Damper at Half-scale Laboratory Steel Frame with MR Damper at NCREE, TaiwanNCREE, Taiwan
33
From Wire-based Sensing to Wireless SensingFrom Wire-based Sensing to Wireless Sensing
DISADVANTAGES OF WIRED CHANNELS
E. G. Straser, and A. S. Kiremidjian (1998): Installation of wired system can take about 75% of testing time for large structures
M. Celebi (2002): Each sensor channel $5,000, half of the cost on installation (cabling, labor, etc.)
I. Solomon, J. Cunnane, P. Stevenson (2000): over 1000 sensors on Tsing Ma Bridge, Kap Shui Mun Bridge, and Ting Kau Bridge. 36 km of copper cable and 14 km of fiber optic cable. 1 year installation.
Traditional DAQ: Wire-based
Future Wireless DAQ System
Wireless SHM prototype system Jointly developed by researchers in Stanford Univ.
and the Univ. of Michigan
44
CHALLENGES
Limited power consumption
Restricted wireless communication range, bandwidth, reliability
Difficulty for data synchronization and real-time data delivery
SYSTEM DESIGN PRINCIPLES
Judicious hardware component selection
Simple, efficient, and robust software design
Challenges in Wireless Structural SensingChallenges in Wireless Structural Sensing
55
Sensor SignalDigitization
4-channel 16-bitAnalog-to-Digital
Converter ADS8341
Computational Core
WirelessCommunication
Wireless Transceiver:20kbps 2.4GHz
24XStream, or 40kbps900MHz 9XCite
StructuralSensors
128kB ExternalSRAM
CY62128B
8-bit Micro-controller
ATmega128
SPIPort
ParallelPort
UARTPort
Wireless Sensing Unit
Functional Diagram of Wireless Sensing UnitFunctional Diagram of Wireless Sensing Unit
66
Final Package of the Latest Prototype UnitFinal Package of the Latest Prototype Unit
Antenna Length: 5.79” (14.7cm)
Container Dimension4.02” x 2.56” x 1.57”(10.2 x 6.5 x 4.0 cm)
Total power consumption with MaxStream 9XCite modem
75 – 80 mA when active; 0.1 mA standby. (5 VDC)
Wireless communication MaxStream transceiver
9XCite: 90 m indoor, 300 m outdoor, 38.4 kbps
24XStream: 150 m indoor, 5 km outdoor, 19.2 kbps
Total unit cost using off-the-shelf components
$130 for small quantity assembly (2004)
77
Wireless Sensing NetworkWireless Sensing Network
Simple star topology network
Near-synchronized and reliable data collection from all wireless sensing units
Communication protocol design using state-machine concept
Firmware for wireless sensing units
Server-side computer software
88
Geumdang Bridge Test, KoreaGeumdang Bridge Test, Korea
Collaboration with Prof. Chung Bang Yun, Prof. Jin Hak Yi, and Mr. Chang Geun Lee, Korea Advanced Institute of Science and Technology (KAIST)
12.6 m
2.6 m
2o
SECTION A-A
ElastomericPad
AccelerometerLocation
99
Wire-based System vs. Wireless SystemWire-based System vs. Wireless System
Sensor PropertyPCB393 Piezoelectric(Cabled System)
PCB3801 MEMS Capacitive(Wireless System)
Maximum Range 0.5g 3g
Sensitivity 10 V/g 0.7 V/g
RMS Resolution (Noise Floor) 50 g 500 g
Minimal Excitation Voltage 18 VDC 5 VDC
Sampling Frequency 200Hz 200Hz / 70Hz
1010
Comparison Between Two SystemsComparison Between Two Systems
155 160 165 170 175 180 185 190-0.04
-0.02
0
0.02
0.04Wire-based DAQ, Sensor #13
Time(s)Acc
eler
atio
n (g
)
155 160 165 170 175 180 185 190-0.04
-0.02
0
0.02
0.04Wireless DAQ, Sensor #13
Time(s)Acc
eler
atio
n (g
)
0 5 10 150
1
2
FFT - Wire-based DAQ, Sensor #13
Frequency (Hz)Mag
nitu
de
0 5 10 150
0.2
0.4
0.6
0.8
FFT - Wireless DAQ, Sensor #13
Frequency (Hz)
Mag
nitu
de
Accelerometer Location
Abutment
Pier 5 Pier 6Pier 4
14
1 13
16
12
1817
2
19
3
26
4
25
5
24
6
15
7
23
8
22
9
21
10
20
11
36m 36m46m
N
1111
Sensor SignalDigitization
4-channel 16-bitAnalog-to-Digital
Converter ADS8341
Computational Core
WirelessCommunication
Wireless Transceiver:20kbps 2.4GHz
24XStream, or 40kbps900MHz 9XCite
StructuralSensors
128kB ExternalSRAM
CY62128B
8-bit Micro-controller
ATmega128
SPIPort
ParallelPort
UARTPort
Wireless Sensing Unit
Sensor SignalConditioning
Amplfication, Filtering,and Voltage-offsettng
Functional Diagram with Sensor Signal Conditioning ModuleFunctional Diagram with Sensor Signal Conditioning Module
1212
Latest Bridge Tests with Sensor Signal ConditioningLatest Bridge Tests with Sensor Signal Conditioning
Mean shifting: any analog signal to 2.5V mean
Amplification: 5, 10 or 20
Anti-alias filtering: band pass 0.02Hz – 25Hz
Sensor Allocation for Tests at Geumdang Bridge, Jul 2005
Abutment
Pier 5 Pier 6Pier 4
8 10 1211
1
13
2 3 4
9
5 6
14
7
38m 38m46m
Accelerometer Location
N
Printed circuit board of the signal conditioning module
(5.0 × 6.5 cm)
1313
0 5 10 150
2
4
FFT - Wire-based DAQ
Frequency (Hz)Mag
nitu
de
0 5 10 150
2
4
FFT - Wireless DAQ
Frequency (Hz)
Mag
nitu
de
15 20 25 30 35-0.04
-0.02
0
0.02Wire-based DAQ
Time (s)
Acc
eler
atio
n (g
)
15 20 25 30 35
-0.02
0
0.02Wireless DAQ
Time (s)Acc
eler
atio
n (g
)
Comparison for Wireless DAQ with Signal Conditioning Comparison for Wireless DAQ with Signal Conditioning
28 29 30 31 32 33-0.03
-0.02
-0.01
0
0.01
0.02Comaprison between Wire-based and Wireless DAQ
Time (s)
Acc
eler
atio
n (g
)
Wire-basedWireless
2.5 3 3.5 4 4.5 50
1
2
3
4
5Comparison between FFT to the Acceleration Data
Frequency (Hz)
Mag
nitu
de
Wire-basedWireless
Prof. J.P. Lynch, University of Michigan. Presentation at 10:50 am, Tue. Session 3, Room: Sunset.
1414
Collaboration with Prof. C. H. Loh, National Taiwan University &
National Center for Research on Earthquake Engineering (NCREE)
Laboratory 3-Story Structure on a 6-DOF Shaking TableLaboratory 3-Story Structure on a 6-DOF Shaking Table
WSU6
A3
A2A1
WSU5
A5
A4
WSU4
A6
A7
WSU1
A11
A10
A8
A12
A9WSU2
WSU3
S41 S42
S43S44
1515
Field Validation Tests at Gi-lu Bridge, Chi-chi, TaiwanField Validation Tests at Gi-lu Bridge, Chi-chi, Taiwan
Gi-lu Cable-Stayed Bridge, Chi-chi,
Taiwan
Span: 120m (L) + 120m (R)
Prof. C.-H. Loh, National Taiwan University. Presentation at 9:20 am, Tue. Session 10, Room: Towne
Vertical Dir.
Chi-chi side
Lu-Ku sideU1 U2 U3 U4 U5
U6 U7 U8 U9
1616
Sensor SignalDigitization
4-channel 16-bitAnalog-to-Digital
Converter ADS8341
Computational Core
WirelessCommunication
Wireless Transceiver:20kbps 2.4GHz
24XStream, or 40kbps900MHz 9XCite
StructuralSensors
128kB ExternalSRAM
CY62128B
8-bit Micro-controller
ATmega128
SPIPort
ParallelPort
UARTPort
Wireless Sensing Unit
Sensor SignalConditioning
Amplfication, Filtering,and Voltage-offsettng
Actuation SignalGeneration
16-bitDigital-to-Analog
Converter AD5542
SPIPort
StructuralActuators
Functional Diagram with Actuation Signal Generation ModuleFunctional Diagram with Actuation Signal Generation Module
1717
Integrated Switching Regulator PT5022
Command Signal Output
Digital Connections to ATmega128 Micro-
controller
Analog Connections to ATmega128 Micro-
controller
Digital-to-Analog Converter AD5542
Operational Amplifier LMC6484
Control Signal Generation ModuleControl Signal Generation Module
Supply voltage: 5 VDC
Output signal: -5 ~ 5 VDC
Output settling time: 1 s
Size: 5.5 x 6.0 cm
1818
20 kN Magneto-Rheological (MR) Damper
Wireless Feedback Structural Control TestsWireless Feedback Structural Control Tests
Collaboration with Prof. C. H. Loh, National Taiwan University &
National Center for Research on Earthquake Engineering (NCREE)
Floor: 3m x 2m
Floor weight: 6,000 kg
Inter-Story height: 3m
Shaking table: 5m x 5m
1919
S3
S2
S1
C1
Ci: wireless control unit
Si: wireless sensing unit
Ti: wireless transceiver
T1
Lab experimentcommand server
Actuator
Wireless Sensing and Control System OverviewWireless Sensing and Control System Overview
Time step length:
20 ms with 9XCite transceiver
80 ms with 24XStream transceiver
4. S1 sends out sensor data toC1; S2 and S3 back off a fewmilli-seconds respectively,and then send data to C1
Major Program Flow for a WiSSCon Laboratory Test
1. The server checks thewireless sensing and controlunits in the network throughthe wireless transceiver T1
2. The shaking tablestarts an earthquakerecord
3. C1 broadcasts a beaconsignal to all the units in thenetwork, announcing that anew time step begins
5. C1 analyzes all the sensordata, decides the controlsignal and applies the signalto the structural controller
6. The server overhears all thewi re les s c om m un i c a t i onthrough T1, and logs the datain the computer hard disk
Loop at each time step
2020
kuBkzAkz ddddd 1
kx
kxkz
d
dd
0 and 0 where
,1
0
RQ
kRukukQzkzkQzkzuJfk
kd
Tdd
Tdfd
Tfdd
kGzku dd
Embedded Computing (1)Embedded Computing (1)
Discretized Linear Quadratic Regulator (LQR) Control Algorithm:
Minimize index:
Optimal control force:
LQR ComputingReal-time sensor data
Desired control force
2121
5
1
0 1 1 2
3 21
2
( ) ( ) ( )
( ) ( 1) ( 1) ( 1)
( ) [ ( ), ( ) ( ) ( ), ( ) ( ) , ( ) ( ) ( ), ( ) ( ) ]
( ) (0.0083 ( ) 0.005) ( )
-13.2924V 22.9678V +1.0297 V - 1.0762
-161
d
i ii
T
d
F t F t z t
z k z k k k dt
k x k x k z k z k x k z k x k z k z k x k z k
F t V t x k
2
23
24
25
.6060V - 88.7154V - 389.2721
-5.0428V -169.2379V-160.4490
-0.6433V - 8.0282V- 0.7757
0.3452V - 6.775V- 0.316
Embedded Computing (2)Embedded Computing (2)
Modified Bouc-Wen MR damper model developed by researchers at NCREE:
MR Damper Model Computing
Desired control force
Appropriate actuation voltage to the MR damper
2222
0 0.002 0.004 0.006 0.008 0.01 0.0120
1
2
3
Drift (m)
Flo
or
Maximum Inter-story Drifts
Damper Volt = 0VDamper Volt = 1VWireless SystemWired System
Preliminary Structural Control TestsPreliminary Structural Control Tests
2323
Future Research in Wireless Sensing and ControlFuture Research in Wireless Sensing and Control
Collaboration with Prof. C. H. Loh, National Taiwan University &
National Center for Research on Earthquake Engineering
Explore more wireless communication technologies
Multiple MR dampers
Decentralized Control
2424
AcknowledgementAcknowledgement
Prof. Chung Bang Yun, Prof. Jin Hak Yi, and Mr. Chang Geun Lee, Korea Advanced Institute of Science and Technology (KAIST)
Prof. Anne Kiremidjian from Civil Engineering, and Prof. Ed Carryer from Mechanical Engineering at Stanford University
National Science Foundation CMS-9988909 and CMS-0421180
Office of Naval Research Young Investigator Program awarded to Prof. Lynch at University of Michigan.
The Office of Technology Licensing Stanford Graduate Fellowship
2525
The EndThe End