#### Transcript Structural Control II - Smart Structures Technology Laboratory

Asia-Pacific Student Summer School on Smart Structures Technology KAIST, Daejeon, Korea August 1, 2008 Day 2. Lecturers: H.-J. Jung, H. Myung, KAIST, Korea Assistants: S.H. Park, D.D. Jang, KAIST, Korea Lab. Schedule Time 8/1 (Fri) 13:00-17:00* Topics 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 2 MR Damper-based Semiactive Control System Experimental Setup 3 MR Damper-based Semiactive Control System Control Algorithm: Modal Neuro Control 4 MR Damper-based Semiactive Control System Experimental Test Results 5 MR Damper-based Semiactive Control System Experimental Test Results 6 Active Control Using PiezoActuator Experimental Setup PZT actuator PZT sensor Notebook DAQ Terminal block Power Amplifier 7 Active Control Using PiezoActuator Experimental Setup 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) 8 Active Control Using PiezoActuator Sample Control Algorithm: PPF Control The equation of motion of the beam: My Cy Ky Lu where, (1) 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). M q C q K q Lu → T M q T C q T K q T Lu Since, it is orthogonal among the modes, the equation of motion can be written as follows: qi 2 ii qi i2 qi Leui where, , : damping ratio and natural frequency of the beam. (2) 9 Active Control Using PiezoActuator Sample Control Algorithm: PPF Control The control input u is generated by the PPF control scheme as u H ̂ Where, ̂ (3) is the output vector from a set of PPF filters described as ˆ 2 ccˆ c2ˆ c2 q where, (4) c , c : the PPF filter frequency and damping ratio. Then, the equation (2) can be rewritten as qi 2 ii qi i2 qi Le Hˆ Since, Le H is square matrix, let’s define a new signal gi2 Le Hˆ where, g is the control gain. (5) , which satisfies (6) 10 Active Control Using PiezoActuator Sample Control Algorithm: PPF Control The resultant closed-loop system can be written as qi 2 ii qi i2 qi gi2 (7) 2 cc c2 c2 q (8) qi 2 ii qi qi 0 2 i g qi structure 2 i c2 2 cc c2 0 compensator < The block diagram of PPF controller > 11 Active Control Using PiezoActuator MATLAB Simulink Block for Experiment 1 Analog Input 2 Analog Input National Instruments DAQCard-6062E [auto] PZT sensor -K- x' = Ax+Bu y = Cx+Du control gain 4 PPF control 3 5 PZT actuator Sine Wave1 0 Constant Analog Output 0 Clock3 0 Clock2 0 Clock1 Analog Output Switch3 National Instruments DAQCard-6062E [auto] Switch2 Sine Wave Switch1 6 12 Active Control Using PiezoActuator MATLAB Simulink Block for Experiment 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 ③, else sine wave1 voltage will be provided. ⑤ If time ≤ 60s, the voltage determined by ④, else the voltage calculated by PPF controller will be provided. ⑥ The voltage determined by ⑤ will provided to the PZT actuator through the DAQ card. 13 14 Asia-Pacific Student Summer School on Smart Structures Technology KAIST, Daejeon, Korea July 28-August 16, 2008 Student Competition Project 1: Structural Monitoring Lecturers: J.-J. Lee, Sejong Univ., K.Y. Koo, KAIST, Korea Assistants: H.J. Park, H.J. Kim, KAIST, Korea Student Competition Project 1: Structural Monitoring Problem Description Problems Prob. 1 Prob. 2 Description Damage 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. Monitoring 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 16 Student Competition Project 1: Structural Monitoring Evaluation Criteria* Problems Prob. 1 (50%) Evaluation Criteria 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 * Final evaluation criteria will be announced on 8/6 (Wed). 17 Asia-Pacific Student Summer School on Smart Structures Technology KAIST, Daejeon, Korea July 28-August 16, 2008 Student Competition Prjoect 2: Structural Control Lecturers: H.-J. Jung, H. Myung, KAIST, Korea Assistants: S.-H. Park, D.-D. Jang, KAIST, Korea Student Competition Project 2: Structural Control Problem Description Problems Prob. 1 Prob. 2 Description Vibration 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. Vibration control of cantilever beam using piezo-actuator - Any control algorithm can be used - Neuro-control and fuzzy control are recommended * New specimens for student competition will be distributed on 8/6 (Wed). 19 Student Competition Project 2: Structural Control Evaluation Criteria* Problems Prob. 1 (40%) Evaluation Criteria 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 * Final evaluation criteria will be announced on 8/6 (Wed). 20