Papers by Keyword: Microactuator

Abstract: A friction-free planar motor, which is composed of piezoelectric elements (piezos), is proposed. The motor is based on the principle of an inchworm using levitation mechanisms. The vertical vibration of the piezo generates the levitation force of the motor. The horizontal deformation of the piezo causes the thrust force of the motor. These piezos realizes three degree-of-freedom motion on a flat surface. We measure the displacement in the vertical and horizontal direction of the levitation mechanism. The feasibility of the inchworm using levitation mechanisms is described.

Abstract: A novel piezoelectrically actuated scanning micromirror integrated with angle sensors is presented. The mirror with large size of 3×3mm² locates in the center of the device, and piezoelectric actuators are symmetrically placed on both sides of the mirror. They are connected through torsion bars in which piezoelectric angle sensors are integrated. In order to obtain large deflection angle at a low operation voltage, the new actuator consisting of several parallel piezoelectric cantilevers is adopted. The machematical models of the mirror and piezoelectric actuator are given, and the piezoelectric angle sensors are designed to obtain high sensitivities. The simulation results indicate that the maximum mechanical deflection angle of the micromirror is 12.4° at an operation voltage of 25V, and the maximum output voltage of the angle sensor is 164.3mV. The resonant frequency associated with the torsional mode is 960Hz. The sensitivity of the angle sensor is 13.3mV/° without amplifying. The Scanning miromirror is suitable for optical scanning systems such as the microscope, the micro-spectrometer, the medical imaging, the barcode reader and so on.

Abstract: The giant magneto-strain effect is particularly attractive for actuator applications in micro- and nanometer dimensions as it enables contact-less control of large deformations, which can hardly be achieved by other actuation principles in small space. Two different approaches are being pursued to develop ferromagnetic shape memory (FSMA) microactuators based on the magnetically induced reorientation of martensite variants: (1) the fabrication of free-standing epitaxial Ni-Mn-Ga thin film actuators in a bottom-up manner by magnetron sputtering, substrate release and integration technologies and (2) the top-down approach of thickness reduction of bulk Ni-Mn-Ga single crystals to foil specimens of decreasing thicknesses (200 – 40 μm) and subsequent integration. This review describes the fabrication technologies, procedures for thermo-mechanical training adapted to the quasi-two-dimensional geometries of film and foil specimens as well as the performance characteristics of state-of-the art actuators after processing and training.

Abstract: The main purpose of active flow control research is to develop a cost-effective technology that has the potential for inventive advances in aerodynamic performance and maneuvering compared to conventional approaches. It can be essential to thoroughly understand the flow characteristics of the formation and interaction of a synthetic jet with external crossflow before formulating a practicable active flow control strategy. In this study, the theoretical model used the transient three-dimensional conservation equations of mass and momentum for compressible, isothermal, turbulent flows. The motion of a movable membrane plate was also treated as the moving boundary by prescribing the displacement on the plate surface. The predictions by the computational fluid dynamics (CFD) code ACE+® were compared with measured transient phase-averaged velocities of Rumsey et al. for software validation. The CFD software ACE+® was utilized for numerical calculations to probe the time evolution of the development process of the synthetic jet and its interaction within a turbulent boundary layer flow for a complete actuation cycle.

Abstract: A microactuator with long-travel and high-resolution based on the principle of tribology is presented, which stroke is up to 300mm and displacement resolution is 0.01μm. It resolves the contradiction of large-stroke and high-resolution in macro/micro drive successfully. The dynamic model of the microactuator is set up. The theory analysis on the dynamic character of the system is carried out based on Karnopp “stick-slip” friction model. The physical and mathematical model of the drive part and transmission part are set up respectively by the method of modularization. The transfer function of the system is attained. The tacking simulation is carried out based on fuzzy control with speed change integral, the result is proved that error is 0.004μm.

Abstract: The hysteresis in piezoelectric actuator is the main factor that affects its displacement accuracy, the hysteresis model is set up by using the theory of preisach, and the research on open-loop control of piezoelectric actuator is carried out based on inverse preisach model. The result shows that the model can describe successfully the hysteresis in piezoelectric actuator, predict the displacement after a series of random voltage path perfectly, and improve the hysteresis of displacement effectively, decrease the nonlinear error of system, increase control precision. A new microactuator with high-resolution and large-stroke based on piezoelectric is presented, and the open-loop control is investigated based on inverse preisach model, its stroke is 300mm, the position accuracy is about 0.03μm, the displacement resolution is up to 0.02μm.

Abstract: Dynamic actuation properties of two types of high-speed microactuators utilizing Ti-Ni-based thin films were investigated. One type is a microactuator utilizing a Ti-Ni-Pd thin film which has high transformation temperatures. Cooling rate of a microactuator increases with increasing temperature difference between transformation and atmosphere temperatures, thus the increase in transformation temperature is effective to increase the actuation response. The other type is a microactuator using R-phase transformation of a Ti-Ni thin film which has a narrow transformation temperature hysteresis. The narrow transformation temperature hysteresis of the R-phase transformation is effective to increase the actuation response. Both types of actuators are promising for high response applications. The working frequency of the microactuators reached 100Hz in the two types of microactuators utilizing the martensitic transformation of the Ti-Ni-Pd thin film and the R-phase transformation of the Ti-Ni thin film.