J. S. Chui

Bio: J. S. Chui is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Piezoelectricity & Piezoelectric accelerometer. The author has an hindex of 1, co-authored 1 publications receiving 12 citations.

Dither-motor design with concurrent sensing and actuating piezoelectric materials (Ring laser gyroscope)

Abstract: The authors present an analytical model to predict the model parameters of a dither-motor structure in a ring laser gyroscope in which the piezoelectric sensor and actuator are employed as driving mechanisms to avoid the problem of so-called lock-in effects It is shown that the natural frequency of a dither motor is strongly influenced by: (1) the inertia and stiffness of piezoelectric elements and bonding layers, (2) the location of piezoelectric elements, and (3) the interaction between structural vibration and piezoelectric actuation Conventionally piezoelectric elements are used for sensor and actuator independently A technique for utilizing each of the piezoelectric elements concurrently for dither rate sensing and dither motion actuation is also developed Experimental results show that the system performance and reliability can be significantly increased by accurately predicting the fundamental structural frequency and by implementing the concurrent sensing/actuating technique

Interaction of structure vibration and piezoelectric actuation

Abstract: A stepped beam model is developed to predict analytically the natural frequencies and mode shapes at different piezoelectric sensor/actuator locations The modal solution obtained by including the inertia and stiffness of the surface-bonded piezoelectric materials is applied to investigate the interaction of structure vibration and piezoelectric actuation under closed circuit condition It is shown that a generalized stiffness from electromechanical coupling is induced by the interaction The generalized stiffness is a function of structure mode shapes and piezoelectric sensor/actuator locations, thus either softening or stiffening system stiffness is achievable in closed circuit condition All analytical predictions are validated by modal testing

Mathematical modeling of actively controlled piezo smart structures: a review

Abstract: This is a review paper on mathematical modeling of actively controlled piezo smart structures. Paper has four sections to discuss the techniques to: (i) write the equations of motion (ii) implement sensor-actuator design (iii) model real life environmental effects and, (iv) control structural vibrations. In section (i), methods of writing equations of motion using equilibrium relations, Hamilton`s principle, finite element technique and modal testing are discussed. In section (ii), self-sensing actuators, extension-bending actuators, shear actuators and modal sensors/actuators are discussed. In section (iii), modeling of thermal, hygro and other non-linear effects is discussed. Finally in section (iv), various vibration control techniques and useful software are mentioned. This review has two objectives: (i) practicing engineers can pick the most suitable philosophy for their end application and, (ii) researchers can come to know how the field has evolved, how it can be extended to real life structures and what the potential gaps in the literature are.

Structural vibration suppression by concurrent piezoelectric sensor and actuator

Abstract: An electromechanical model is developed to predict the natural frequencies of a structural system with a piezoelectric sensor and actuator. Analysis shows that a generalized stiffness is induced in the closed-circuit condition and it is a function of the structure dimensions, the location of the piezoelectric elements, and the piezoelectric constant. The sensor and actuator equation derived from the electromechanical model shows that a single piezoelectric element can be employed concurrently in sensing and actuation. Experimental verifications of structural vibration suppression are conducted on a beam structure with surface-bonded piezoelectric elements as well as on two composite laminated structures - and - with embedded piezoelectric sensors and actuators. Compared with previous studies of vibration suppression by separate piezoelectric sensor(s) and actuator(s), the concurrent sensing and actuation technique offers the advantages of improved performance and reliability as each piezoelectric element can be employed as sensor and actuator simultaneously.

Self-Sensing Compounding Control of Piezoceramic Micro-Motion Worktable Based on Integrator

Abstract: The displacement of micro-motion worktable driven by piezoceramic actuator can be measured by self-sensing method in the absence of independent sensor. And a displacement self-sensing control system is made. The free charges on the wafers of piezoceramic actuator contain displacement information. So a displacement self-sensing method of piezoceramic actuator based on integrator is presented. Integrator circuit is designed for gathering free charges on the wafers of actuator. It is convenient to adjust the circuit and easy to acquire sensitive signal using this method. And the impedance mismatching problem met in bridge method is overcome. In order to improve the static and dynamical performance of the piezoceramic micro-motion worktable, the compounding control method by combining feedforward control and feedback control is designed. The self-sensing displacement is the feedback signal of control system of piezoceramic micro-motion worktable. The availability of the self-sensing compounding control is validated by experiment. Comparison experiments among such kind of control, feedforward control, general PID feedback control with independent sensor and compound control with independent sensor are took. The experimental results show that self-sensing compounding control has the same good performance of compounding control with independent sensor.

Parametric design of mechanical dither with bimorph piezoelectric actuator for ring laser gyroscope

Abstract: This paper presents a mathematical model and a finite element model to investigate the model parameters of me- chanical dither in a ring laser gyroscope in which the bimorph piezoelectric actuator are employed as driving mechanisms to avoid the problem of so-called lock-in effects. The validity and efficiency of the mathematical model and finite element model are conformed by comparing with the sinusoidal experimental results, and the errors are 3.14% and 1.79% respectively. Moreover, the parametric design for the geometric dimensions of mechanical dither and the bimorph piezoelectric actuators is easily achieved through finite element model. It is shown that careful selection of the structural parameters allows the resonant frequency to be suitable. These results are important for the mechanical dither design and improvement of high accuracy ring laser gyroscopes and inertial navigation system.