• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.154-157
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• 2000

Distributed piezoelectric sensor and actuator system has been designed for the active vibration control of shell structure. PVDF is used for the materials of sensor/actuator. To prevent the adverse effect of spillover, distributed modal sensor/actuator system is established. Although shell structure is three-dimensional structure, the PVDF sensor/actuator system can be treated as two-dimensional Finite element programs are developed to consider curved structures having PVDF modal sensor/actuator. The nine-node Mindlin shell element with five nodal degree of freedoms is used for finite element discretization. The electrode patterns and lamination angle of PVDF sensor/actuator are optimized to design the modal sensor/actuator system Genetic algorithm is used for optimization. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and second modes of singly curved cantilevered shell structure are designed using mentioned methods. Discrete LQG method is used as a control law. Experimental demonstrations of the active vibration control with designed sensor/actuator system have been performed successfully.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.587-592
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair, because the sensor-actuator pair has strictly positive real (SPR) property. In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB sho robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a 'skyhook' damper, but the point sensor-distributed actuator pair with DVFB acts as a 'skyhook' rotational dmaper pair.ational dmaper pair.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.619-625
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.106-117
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• 2006

The active vibration control of composite shell structure has been performed with the optimized sensor/actuator system. For the design of sensor/actuator system, a method based on finite element technique is developed. The nine-node Mindlin shell element has been used for modeling the integrated system of laminated composite shell with PVDF sensor/actuator. The distributed selective modal sensor/actuator system is established to prevent the effect of spillover. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Continuous electrode patterns are discretized according to finite element mesh, and orientation angle is encoded into discrete values using binary string. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and the second mode vibration control of singly curved cantilevered composite shell structure are designed with the method developed on the finite element method and optimization. For verification, the experimental test of the active vibration control is performed for the composite shell structure. Discrete LQG method is used as a control law.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.413-417
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• 1997

Distributed piezoelectric sensor and actuator have been designed for efficient vibration control of a cantilevered beam. Both PZT and PVDF are used in this study, the former as an actuator and the latter as a sensor for our integrated structure. For the PZT actuator, the position and size have been optimized. Optimal electrode shape of the PVDF sensor has been determined. For multi-mode vibration control, we have used two PZT actuators and a PVDF sensor. Electrode shading of PVDF is more powerful for modal force adjustment than the sizing and positioning of PZT. Finite element method is used to model the structure that includes the PZT actuator and the PVDF sensor. By deciding on or off of each PZT segment, the length and the location of the PZT actuator are optimize. Considering both of the host structure and the optimized actuators, it is designed that the active electrode width of PVDF sensor along the span of the beam. Actuator design is based on the criterion of minimizing the system energy in the control modes under a given initial condition. Sensor is designed to minimize the observation spill-over. Modal control forces for the residual(uncontrolled) modes have been minimized during the sensor design. Genetic algorithm, which is suitable for this kind of discrete problems, has been utilized for optimization. Discrete LQG control law has been applied to the integrated structure for real time vibration control. Performance of the sensor, the actuator, and the integrated smart structure has been demonstrated by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.778-783
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• 2003

The problem considered in this paper is about the collocation of sensor and actuator for the active control of sound and vibration. It is well-known that a point collocated sensor-actuator pair offers an unconditional stability with very high performance when it is used with a direct velocity feedback (DVFB) control, because the pair has strictly positive real (SPR) property. In order to utilize this SPR characteristics, a matched piezoelectric sensor and actuator pair is considered, but this pair suffers from the in-plane motion coupling problem with the out-of$.$plane motion due to the piezo sensor and actuator interaction. This coupling phnomenon limits the stability and performance of the matched pair with DVFB control. As a new alternative, a point sensor and piezoelectric actuator pair is also considered, which provides SPR property in all frequency range except at the first resonance in very low frequency. This non-SPR resonance could be minimized by applying a phase lag compensator.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.6
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• pp.169-174
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• 2001

Optimization of the collocated piezoceramic sensor/actuator placement is investigated numerically and verified experimentally for vibration control of laminated composite plates. The finite element method is used for the analysis of dynamic characteristics of the laminated composite plates with the piezoceramic sensor/actuator. The structural damping index(SDI) is defined from the modal damping(2$\omega$ζ) . It is chosen as the objective function for optimization. Weights for each vibrational mode are taken into account in the SDI calculation. The gradient method is used for the optimization. Optimum location of the piezoceramic sensor/actuator is determined by maximizing the SDI. Numerical simulation and experimental results show that the optimum location of the piezoceramic sensor/actuator is dependent upon the outer layer fiber orientations of the plate, and location and size of the piezoceramic sensor/actuator.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.253-263
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• 2004

The problem considered in this paper is about the collocation of sensor and actuator for the active control of sound and vibration. It is well-known that a point collocated sensor-actuator pair offers an unconditional stability with very high performance when it is used with a direct velocity feedback (DVFB) control, because the pair has strictly positive real (SPR) property. In order to utilize this SPR characteristics, a matched piezoelectric sensor and actuator pair is considered. but this pair suffers from the in-plane motion coupling problem with the out-of-plane motion due to the piezo sensor and actuator interaction. This coupling phnomenon limits the stability and performance of the matched pair with DVFBcontrol. As a new alternative, a point sensor and distributed piezoelectric actuator pair is also considered, which provides SPR property in all frequency range when the pair is implemented on a clamped-clapmed beam. The use of this sensor-actuator pair is highly expected for the applications to more practical active control of sound and vibration systems with the DVFB control strategy.

• Journal of KSNVE
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• v.7 no.6
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• pp.967-974
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• 1997

Distributed piezoeletric sensor and actuator have been designed for efficient vibration control of a cantilevered beam. Both PZT and PVDF have been used in this study, the former as an actuator and the latter as a sensor for the integrated structure. We have optimized the position and the size of the PZT actuator and the electrode shape of the PVDF sensor. Finite element method is used to model the structure and the optimized actuators, we have designed the active electrode width of the PVDF sensor along the span of the beam. Actuator design is based on the criterion of minimizing the system energy in the control modes under a given initial condition. Model control forces for the residual (uncontrolled) modes have been minimized during the sensor design to minimize the observation spill-over. Genetic algorithm and sequential quadratic programming technique have been utilized as an optimization scheme. Discrete LQG control law has been applied to the integrated structure for real time vibration control. Performance of the sensor, the actuator, and the integrated smart structure has been demonstrated by experiments.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.228-231
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• 2000

The active vibration control of laminated composite shell has been performed with the optimized sensor/actuator system. PVDF film is used fur the material of sensor/actuator. Finite element method is utilized to model the whole structure including the piezoelectric sensor/actuator system, The distributed selective modal sensor/actuator system is established to prevent the adverse effect of spillover. In the finite element discretization process, the nine-node shell element with five nodal degrees of freedoms is used. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator profiles are optimized for the first and the second modes suppression of singly curved cantilevered composite shell structure. Discrete LQG method is used as a control law. The real time vibration control with profile optimized sensor/actuator system has been performed. Experimental result shows successful performance of the integrated structure for the active vibration control.