Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
In this paper, two different piezoelectric microactuator designs are studied. The\ncorresponding devices were designed for optimal in-plane displacements and different high\nflexibilities, proven by electrical and optical characterization. Both actuators presented two\ndominant vibrational modes in the frequency range below 1 MHz: an out-of-plane bending and an\nin-plane extensional mode. Nevertheless, the latter mode is the only one that allows the use of the\ndevice as a modal in-plane actuator. Finite Element Method (FEM) simulations confirmed that the\ndisplacement per applied voltage was superior for the low-stiffness actuator, which was also\nverified through optical measurements in a quasi-static analysis, obtaining a displacement per volt\nof 0.22 and 0.13 nm/V for the low-stiffness and high-stiffness actuator, respectively. In addition,\nelectrical measurements were performed using an impedance analyzer which, in combination with\nthe optical characterization in resonance, allowed the determination of the electromechanical and\nstiffness coefficients. The low-stiffness actuator exhibited a stiffness coefficient of 5 Ã?â?? 104 N/m, thus\nbeing more suitable as a modal actuator than the high-stiffness actuator with a stiffness of 2.5 Ã?â?? 105\nN/m....
A linear piezoelectric actuator based on the stick-slip principle is presented and tested\nin this paper. With the help of changeable vertical preload force flexure hinge, the designed linear\nactuator can achieve both large travel stick-slip motion and high-resolution stepping displacement.\nThe developed actuator mainly consists of a bridge-type flexure hinge mechanism, a compound\nparallelogram flexure hinge mechanism, and two piezoelectric stacks. The mechanical structure\nand motion principle of the linear actuator were illustrated, and the finite element method\n(FEM) is adopted. An optimal parametric study of the flexure hinge is performed by a finite\nelement analysis-based response surface methodology. In order to investigate the actuatorâ��s\nworking performance, a prototype was manufactured and a series of experiments were carried out.\nThe results indicate that the maximum motion speed is about 3.27 mm/s and the minimum stepping\ndisplacement is 0.29 �¼m. Finally, a vibration test was carried out to obtain the first natural frequency\nof the actuator, and an in situ observation was conducted to investigate actuatorâ��s stick-slip working\ncondition. The experimental results confirm the feasibility of the proposed actuator, and the motion\nspeed and displacement are both improved compared with the traditional stick-slip motion actuator....
Numbers and locations of sensors and actuators play an important role in cost and control performance for active vibration control\nsystem of piezoelectric smart structure. This may lead to a diverse control system if sensors and actuators were not configured\nproperly. An optimal location method of piezoelectric actuators and sensors is proposed in this paper based on particle swarm\nalgorithm (PSA). Due to the complexity of the frame structure, it can be taken as a combination of many piezoelectric intelligent\nbeams and L-type structures. Firstly, an optimal criterion of sensors and actuators is proposed with an optimal objective function.\nSecondly, each order natural frequency and modal strain are calculated and substituted into the optimal objective function.\nPreliminary optimal allocation is done using the particle swarm algorithm, based on the similar optimization method and the\ncombination of the vibration stress and strain distribution at the lower modal frequency. Finally, the optimal location is given.\nAn experimental platform was established and the experimental results indirectly verified the feasibility and effectiveness of the\nproposed method....
To improve the phase-shifting accuracy, this paper presents a novel integrated framework\nfor design, control and experimental validation of the piezoelectric actuated phase shifter with a\ntrade-off between accuracy and cost. The piezoelectric actuators with built-in sensors are adopted\nto drive the double parallel four-bar linkage flexure hinge-based mechanisms. Three mechanisms\nform the tripod structure of the assembled phase shifter. Then, a semi-closed loop controller with\ninner feedback and outer feedforward loops via the external laser interferometer is developed for\naccurate positioning of the phase shifter. Finally, experiments related with travel range, step response,\nlinearity and repeatability are carried out. The linearity error is 0.21% and the repeatability error of\n10 �¼m displacement is 3 nm. The results clearly demonstrate the good performance of the developed\nphase shifter and the feasibility of the proposed integrated framework....
Nowadays, the haptic effect is used and developed for many applicationsââ?¬â?particularly\nin the automotive industry, where the mechanical feedback induced by a haptic system enables the\nuser to receive information while their attention is kept on the road and on driving. This article\npresents the development of a vibrotactile button based on printed piezoelectric polymer actuation.\nFirstly, the characterization of the electro-active polymer used as the actuator and the development\nof a model able to predict the electromechanical behavior of this device are summarized. Then,\nthe design of circular membranes and their dynamic characterization are presented. Finally, this work\nis concluded with the construction of a fully functional demonstrator, integrating haptic buttons\nleading to a clear haptic sensation for the user....
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