Day 2.

Lecturers: H.-J. Jung, H. Myung, KAIST, Korea

Assistants: S.H. Park, D.D. Jang, KAIST, Korea

Asia-Pacific Student Summer School on Smart Structures TechnologyKAIST, Daejeon, Korea

August 1, 2008

2

Lab. Schedule

Time Topics

8/1 (Fri)13:00-17:00*

Demonstration: MR damper-based semi-active

control Lab.: Active control using piezo-actuator Introduction to student competition:

Project II: Structural Control

*Group 1: 13:00-15:00 Group 2: 15:00-17:00

MR Damper-based Semi-active Control System

3

Experimental Setup

4

Control Algorithm: Modal Neuro Control

MR Damper-based Semi-active Control System

5

MR Damper-based Semi-active Control System

Experimental Test Results

6

Experimental Test Results

MR Damper-based Semi-active Control System

Active Control Using Piezo-Actuator

Experimental Setup

7

Notebook DAQ Terminal block

Power Amplifier

PZT actuator

PZT sensor

Structure Cantilever beam made of aluminum (500(L) ⅹ 50(W) ⅹ 0.8(t) (mm))

Sensor, Compensator & Exciter Piezoceramic patch

Data Acquisition & Real Time Control Hardware: NI DAQCard-6062E for PCMCIA & Terminal Block

BNC-2110 Software: MATLAB Real Time Workshop

Other Equipments Power Amplifier (or High Voltage Amplifier)

Control Algorithm for active control Positive Position Feedback (PPF) Control (sample controller)

Active Control Using Piezo-Actuator

8

Experimental Setup

9

The equation of motion of the beam:

where, M, C, K : mass, damping, stiffness matrix of the beam

y(x,t) : displacement at the position y and time t

u : control input L: the location defining vector for u

The y(x,t) can be rewritten as the product of mode shape φ(x) and modal coordinate q(t).

→

Since, it is orthogonal among the modes, the equation of motion can be written as follows:

where, : damping ratio and natural frequency of the beam.

LuKyyCyM

LuqKqCqM LuqKqCqM TTTT

ieiiiiii uLqqq 22

,

(1)

(2)

Active Control Using Piezo-Actuator

Sample Control Algorithm: PPF Control

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The control input u is generated by the PPF control scheme as

Where, is the output vector from a set of PPF filters described as

where, : the PPF filter frequency and damping ratio.

Then, the equation (2) can be rewritten as

Since, is square matrix, let’s define a new signal , which satisfies

where, g is the control gain.

Hu

qcccc22 ˆˆ2ˆ

cc ,

(3)

(4)

ˆ2 2 HLqqq eiiiiii (5)

HLe ˆ2 HLg ei (6)

Active Control Using Piezo-Actuator

Sample Control Algorithm: PPF Control

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The resultant closed-loop system can be written as(7)

(8)

222 iiiiiii gqqq qcccc

222

02 2 iiiiii qqq

structure2c

02 2 ccc

compensator

2ig

iq

< The block diagram of PPF controller >

Active Control Using Piezo-Actuator

Sample Control Algorithm: PPF Control

12

-K-

control gain

Switch3

Switch2

Switch1

Sine Wave1

Sine Wave

PZT sensor

PZT actuator

x' = Ax+Bu y = Cx+Du

PPF control

0

Constant 0

Clock30

Clock20

Clock1

AnalogOutput

Analog OutputNational Instruments

DAQCard-6062E [auto]

AnalogInput

Analog InputNational Instruments

DAQCard-6062E [auto]

1

3

4

5

6

2

Active Control Using Piezo-Actuator

MATLAB Simulink Block for Experiment

13

① The voltage generated by PZT sensor is acquired through the DAQ card.

② PPF controller, which calculates the required control voltage.

③ If 0≤ time ≤ 20s, sine wave, else zero voltage will be provided.

④ If time ≤ 45s, the voltage determined by , else sine wave1 voltage will be provided.③

⑤ If time ≤ 60s, the voltage determined by , else the voltage calculated by PPF controller ④

will be provided.

⑥ The voltage determined by will provided to the PZT actuator through the DAQ card.⑤

Active Control Using Piezo-Actuator

MATLAB Simulink Block for Experiment

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Student CompetitionProject 1: Structural

Monitoring

Lecturers: J.-J. Lee, Sejong Univ., K.Y. Koo, KAIST, Korea

Assistants: H.J. Park, H.J. Kim, KAIST, Korea

Asia-Pacific Student Summer School on Smart Structures TechnologyKAIST, Daejeon, Korea

July 28-August 16, 2008

Student CompetitionProject 1: Structural

Monitoring

16

Problems Description

Prob. 1Damage detection on a steel beam

- All data sets including baseline and 3 unknown states will be provided. - Identify damage existence, location and severity if possible. - You CAN use ANY algorithm and software, not limited to the peak-picking method and IDIS.

Prob. 2Monitoring of model structures

- Make each team’s own structure using pieces of steel beams which are provided. - Establish monitoring strategies fit to each structure. - Introduce damages - Perform vibration tests and damage identification

Problem Description

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Problems Evaluation Criteria

Prob. 1(50%)

Damage identification results for 3 unknown data sets Programming skills for demonstration New methodologies (probably) will get additional points

Prob. 2(50%)

Novelty of problem definition (structure, damage type,

algorithms, etc.) Completeness of procedures Presentation/Demonstration skills Teamwork

Evaluation Criteria*

* Final evaluation criteria will be announced on 8/6 (Wed).

Student CompetitionProject 1: Structural

Monitoring

Student Competition

Prjoect 2: Structural Control

Lecturers: H.-J. Jung, H. Myung, KAIST, Korea

Assistants: S.-H. Park, D.-D. Jang, KAIST, Korea

Asia-Pacific Student Summer School on Smart Structures TechnologyKAIST, Daejeon, Korea

July 28-August 16, 2008

Student CompetitionProject 2: Structural

Control

19

Problems Description

Prob. 1Vibration control of cantilever beam using

piezo-actuator - Strain-rate feedback (SRF) control algorithm - SRF control algorithm can be obtained by slightly modifying PPF control algorithm.

Prob. 2Vibration control of cantilever beam using

piezo-actuator - Any control algorithm can be used - Neuro-control and fuzzy control are recommended

Problem Description

* New specimens for student competition will be distributed on 8/6 (Wed).

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Problems Evaluation Criteria

Prob. 1(40%)

Damping ratio (50%) Settling time (5% of the initial value) (30%) Overshooting (20%)

Prob. 2(40%)

Completeness of control algorithm (40%) Damping ratio (30%) Settling time (5% of the initial value) (20%) Overshooting (10%)

Presentation(20%)

Presentation and demonstration skills Teamwork

Student CompetitionProject 2: Structural

Control Evaluation Criteria*

* Final evaluation criteria will be announced on 8/6 (Wed).