Lanczos Eigensolver with Reverse Communication Interface

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					Wireless Structural Sensing and Feedback
   Control 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

                                                                    1
Outline


         Research Background

         Hardware and Software Design of the Wireless Structural
          Sensing System
         Validation Tests: Geumdang Bridge, Korea
               Laboratory Steel Frame at NCREE, Taiwan
               Gi-lu Bridge, Taiwan

         Hardware and Software Design of the Wireless Feedback
          Structural Control System
         Half-scale Laboratory Steel Frame with MR Damper at
          NCREE, Taiwan




                                                                    2
From Wire-based Sensing to Wireless Sensing

                                                      Traditional DAQ: Wire-based
   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
                                                      Future Wireless DAQ System
       (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                  Wireless SHM prototype
       installation.                                     system Jointly developed by
                                                        researchers in Stanford Univ.
                                                          and the Univ. of Michigan


                                                                                        3
Challenges in Wireless Structural Sensing



                                  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




                                                                         4
Functional Diagram of Wireless Sensing Unit




                                              5
Final Package of the Latest Prototype Unit

     Antenna Length:
     5.79” (14.7cm)

                                                           Container Dimension
                                                           4.02” 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)

                                                                                   6
Wireless Sensing Network


                                                 Server-side
                                                 computer software




                                                   Firmware for
                                                   wireless sensing
                                                   units


     Simple star topology network
     Near-synchronized and reliable data collection from all wireless
      sensing units
     Communication protocol design using state-machine concept

                                                                         7
Geumdang 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
                                     2o

   2.6 m
                            Elastomeric
                                Pad
            Accelerometer
              Location




           SECTION A-A




                                                                                     8
Wire-based System vs. Wireless System




                              PCB393 Piezoelectric   PCB3801 MEMS Capacitive
 Sensor Property
                              (Cabled System)        (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


                                                                               9
Comparison Between Two Systems
                                                                                                                               Accelerometer Location
                             Pier 4                  Pier 5                                             Pier 6
                                             1       2    3   4   5     6    7    8   9 10 11                   12        13
                                                                                                                                           Abutment
                                             14     17    19 26 25 24 15 23 22 21 20                            18        16

                                            36m                             46m                                           36m
                                                                                                                                                   N




                                Wire-based DAQ, Sensor #13                                                           FFT - Wire-based DAQ, Sensor #13
                      0.04
   Acceleration (g)




                                                                                            Magnitude
                      0.02                                                                              2
                        0
                                                                                                        1
               -0.02                                                                                                                               Frequency (Hz)
                                                                  Time(s)
               -0.04                                                                                    0
                   155       160    165 170 175 180 185                      190                            0                5           10                  15
                                   Wireless DAQ, Sensor #13                                                           FFT - Wireless DAQ, Sensor #13
                      0.04
   Acceleration (g)




                      0.02
                                                                                        Magnitude   0.8
                                                                                                    0.6
                        0
                                                                                                    0.4                                         Frequency (Hz)
               -0.02                                                                                0.2
                                                                      Time(s)
               -0.04                                                                                  0
                   155       160      165     170   175    180    185        190                            0                  5              10             15



                                                                                                                                                                    10
Functional Diagram with Sensor Signal Conditioning Module




                                                            11
Latest 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
  Printed circuit board of the
  signal conditioning module
         (5.0 × 6.5 cm)
                                                                   Accelerometer Location
              Pier 4             Pier 5                   Pier 6
                         1          2     3     4    5     6        7
                                                                                  Abutment
                         8          9     10   11    12   13        14

                        38m                    46m                 38m
                                                                                            N




           Sensor Allocation for Tests at Geumdang Bridge, Jul 2005



                                                                                                12
Comparison for Wireless DAQ with Signal Conditioning
                                               Wire-based DAQ                                                  FFT - Wire-based DAQ
        Acceleration (g)    0.02
                                                                                                 4




                                                                                     Magnitude
                               0
                                                                                                 2
                    -0.02
                                                                      Time (s)                                                    Frequency (Hz)
                    -0.04                                                                        0
                         15               20         25         30              35                   0           5            10            15
                                               Wireless DAQ                                                     FFT - Wireless DAQ
                            0.02
          Acceleration (g)




                                                                                                 4




                                                                                     Magnitude
                               0
                                                                                                 2
                    -0.02
                                                                      Time (s)                                                  Frequency (Hz)
                                                                                                 0
                                15        20          25        30              35                   0           5           10             15

                               Comaprison between Wire-based and Wireless DAQ                    Comparison between FFT to the Acceleration Data
                             0.02                                                                5
                                                              Wire-based                                  Wire-based
                                                              Wireless                                    Wireless
                             0.01                                                                4
         Acceleration (g)




                                                                                     Magnitude
                               0                                                                 3


                     -0.01                                                                       2


                     -0.02                                                                       1

                                                                     Time (s)                                                     Frequency (Hz)
                     -0.03                                                                       0
                          28            29       30        31        32         33               2.5       3         3.5    4         4.5      5


Prof. J.P. Lynch, University of Michigan. Presentation at 10:50 am, Tue. Session 3, Room: Sunset.                                                  13
 Laboratory 3-Story Structure on a 6-DOF Shaking Table
                                                                                    A1           A2
Collaboration with Prof. C. H. Loh, National Taiwan University &
                                                                                                       A3
National Center for Research on Earthquake Engineering (NCREE)
                                                                                          WSU6




                                                                                    A8           A4

                                                                                                       A5
                                                                                          WSU5




                                                                                    A12          A7

                                                                                                       A6
                                                                                          WSU4




                                                                        S44   S43
                                                                 WSU2               A9           A10

                                                                                                       A11
                                                                        S41   S42
                                                                                          WSU1
                                                                 WSU3



                                                                                                             14
Field Validation Tests at Gi-lu Bridge, Chi-chi, Taiwan
Prof. C.-H. Loh, National Taiwan University. Presentation at 9:20 am, Tue. Session 10, Room: Towne




                                                                                    Gi-lu Cable-Stayed
                                                                                     Bridge, Chi-chi,
                                                                                          Taiwan
                                                                                    Span: 120m (L) +
                                                                                       120m (R)




                                      Vertical Dir.


                                                                                      U8   U9
                                                                          U6   U7
                                                           U3   U4   U5
                                            U1        U2
                                                                                                Lu-Ku side

                             Chi-chi side




                                                                                                             15
Functional Diagram with Actuation Signal Generation Module




                                                             16
Control Signal Generation Module


       Digital Connections to                                          Integrated Switching
   ATmega128 Micro-controller                                          Regulator PT5022



                                                                       Command Signal
       Analog Connections to                                           Output
   ATmega128 Micro-controller


                                 Digital-to-Analog   Operational Amplifier
                                Converter AD5542     LMC6484


                                     Supply voltage: 5 VDC
                                     Output signal: -5 ~ 5 VDC
                                     Output settling time: 1 s
                                     Size: 5.5 x 6.0 cm

                                                                                              17
 Wireless 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
                                                            20 kN Magneto-Rheological (MR) Damper
   Inter-Story
      height: 3m
   Shaking table:
     5m x 5m




                                                                                                18
Wireless Sensing and Control System Overview


                                   Major Program Flow for a WiSSCon Laboratory Test
                              1. The server checks the
                              wireless sensing and control      2. The shaking table
                              units in the network through      starts an earthquake
                              the wireless transceiver T1       record

                                                                3. C1 broadcasts a beacon
                             4. S1 sends out sensor data to     signal to all the units in the
                             C 1 ; S 2 and S 3 back off a few   network, announcing that a
                             milli-seconds respectively,        new time step begins
                             and then send data to C1

                                                                5. C1 analyzes all the sensor
                             6. The server overhears all the    data, decides the control
                             wireless com m unication           signal and applies the signal
                             through T 1, and logs the data     to the structural controller
                             in the computer hard disk
                                                                    Loop at each time step




                                 Time step length:
                                 20 ms with 9XCite transceiver
                                 80 ms with 24XStream transceiver



                                                                                                 19
Embedded Computing (1)

  Discretized Linear Quadratic Regulator (LQR) Control Algorithm:

                                                                        x k 
                 z d k 1  Ad z d k   Bd ud k       z d k    d 
                                                                        x d k 
                                                                         

  Minimize index:
                                               k f 1
                             T Qz d k f   zd k T Qzd k   ud k T Rud k ,
            J u d   z d k f
                                                k 0
           where Q  0 and R  0


  Optimal control force:
                                   u d k   Gz d k 


       Real-time                   LQR Computing                           Desired
       sensor data                                                         control force

                                                                                           20
Embedded Computing (2)

  Modified Bouc-Wen MR damper model developed by researchers at NCREE:

            F (t )  F (t )  z (t )
                       d

                                    5

            z (k )  z (k  1)   i (k  1)i (k  1)dt
                                  i 1

            (k )  [ x(k ), x(k ) z (k ) 0 z (k ), x (k ) z (k ) 1 , x (k ) z (k ) 1 z (k ), x (k ) z (k ) 2 ]T
           
            Fd (t )  (0.0083V (t )  0.005)x(k )
           
           
           1  -13.2924V  22.9678V +1.0297 V - 1.0762
                                  3               2

           
              2  -161.6060V - 88.7154V - 389.2721
                                    2
           
             -5.0428V 2 -169.2379V-160.4490
            3
            4  -0.6433V 2 - 8.0282V- 0.7757
           
           5  0.3452V - 6.775V- 0.316
                               2
           

                                                                                   Appropriate
     Desired                     MR Damper Model
                                                                                   actuation voltage to
     control force                  Computing
                                                                                   the MR damper
                                                                                                                     21
Preliminary Structural Control Tests


                                      Maximum Inter-story Drifts
                      3
                              Damper Volt = 0V
                              Damper Volt = 1V
                              Wireless System
                              Wired System
                      2
              Floor




                      1




                      0
                          0   0.002    0.004      0.006      0.008   0.01   0.012
                                                 Drift (m)




                                                                                    22
Future 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




                                                                   23
Acknowledgement



     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




                                                                            24
The End




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