Dynamic behaviour of a magnetically actuated floating liquid marble

This paper reports the dynamic behaviour of a magnetically actuated floating liquid marble by analysing the oscillation of the marble. A liquid marble is a liquid droplet coated with hydrophobic powder. Magnetite particles inside the marble make it magnetic. The marble floats on a carrier liquid that contains aqueous glycerol of various concentrations. A permanent magnet located under the carrier liquid drives the floating marble with the initial velocity. Stopping the magnet abruptly causes the marble to oscillate around its final position for a few seconds. The oscillation was recorded and analysed using customised image processing and evaluation software. The damped harmonic motion model was then applied to the data and tested. Subsequently, critical parameters of the system such as the initial displacement, friction correction factor, the apparent frequency and the spring constant were determined and discussed. The simple experimental set-up and convenient theoretical approach allow us to characterise the marble motion under the influence of a magnet with good accuracy.     

Design and simulation of a thermally actuated MEMS switch for microwave circuits

The design, modeling, and optimization of a novel, thermally actuated CMOS‐MEMS switch are presented in this article. This series capacitive MEMS switch solves the substrate loss and down‐state capacitance degradation problems commonly plaguing MEMS switches. The switch uses finger structure for capacitive coupling. The vertical bending characteristic of bimorph cantilever beams under different temperatures is utilized to turn the switch on and off. A set of electrical, mechanical, and thermal models is established, and cross‐domain electro‐thermo‐mechanical simulations are performed to optimize the design parameters of the switch. The fabrication of the switch is completely CMOS‐process compatible. The design is fabricated using the AMI 0.6 μm CMOS process and a maskless reactive‐ion etching process. The measured results show the insertion loss and isolation are 1.67 and 33 dB, respectively, at 5.4 GHz, and 0.36 and 23 dB at 10 GHz. The actuation voltage is 25 V and the power consumption is 480 mW. This switch has a vast number of applications in the RF/microwave field, such as configurable voltage control oscillators, filters, and configurable matching networks. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Wavelength converter sharing in a WDM optical packet switch: dimensioning and performance issues

This paper analyses the performance of an optical packet switch making use of fiber delay-lines to resolve output packet contentions and equipped with a set of tunable wavelength converters (TOWCs) shared among the input lines. The wavelength converters can shift optical packets to any wavelength of the output link which they are directed to. An analytical model is developed to evaluate the number of TOWCs needed to satisfy given performance requirements. Moreover, a sensitivity analysis with respect to both the optical packet switch parameters and the traffic load is carried out. The obtained results show that the number of converters needed to maintain the packet loss probability is much lower than that needed by the switches proposed in literature.     

Model predictive control of magnetically actuated mass spring dampers for automotive applications

Mechatronic systems such as those arising in automotive applications are characterized by significant non-linearities, tight performance specifications as well as by state and input constraints which need to be enforced during system operation. This paper takes a view that model predictive control (MPC) and hybrid models can be an attractive and systematic methodology to handle these challenging control problems, even when the underlying process is not hybrid. In addition, the piecewise affine (PWA) explicit form of MPC solutions avoids on-line optimization and can make this approach computationally viable even in situations with rather constrained computational resources. To illustrate the MPC design procedure and the underlying issues, we focus on a specific non-linear process example of a mass spring damper system actuated by an electromagnet. Such a system is one of the most common elements of mechatronic systems in automotive systems, with fuel injectors representing a concrete example. We first consider a linear MPC design for the mechanical part of the system. The approach accounts for all the constraints in the system but one, which is subsequently enforced via a state-dependent saturation element. Second, a hybrid MPC approach for the mechanical subsystem is analysed that can handle all the constraints by design and achieves better performance, at the price of a higher complexity of the controller. Finally, a hybrid MPC design that also takes into account the electrical dynamics of the system is considered.     

Numerical simulation and analysis of electrically actuated microbeam-based MEMS capacitive switch

The MEMS capacitive switch based on fixed-fixed microbeam has garnered significant attention due to their geometric simplicity and broad applicability. The accurate model which describes the multiphysical coupled-field of MEMS capacitive switch should be developed to predict their electromechanical behaviors. The improved macromodel of the fixed-fixed microbeam-based MEMS capacitive switch is presented to investigate the behavior of electrically actuated MEMS capacitive switch in this paper, the macromodel provides an effective and accurate design tool for this class of MEMS devices because of taking account into some effects simultaneously including fringing field effect, midplane stretching effect, residual stress and multiphysical coupled-field effect. The numerical analysis of mechanical characterizations of electrically actuated microbeam-based MEMS capacitive switch are performed by the finite element Newmark method, and the performances of static and dynamic of MEMS capacitive switch are obtained. The numerical results show that, with only a few nodes used in the computation, the FEM-Newmark gives the identical results to other numerical methods, such as the shooting method and experiments. Moreover, the proposed model can offer proper and convenient approach for numerical calculations, and promote design of MEMS devices.     

Design and nonlinear servo control of MEMS mirrors and their performance in a large port-count optical switch

In this paper, we demonstrate full closed-loop control of electrostatically actuated double-gimbaled MEMS mirrors and use them in an optical cross-connect. We show switching times of less than 10 ms and optical power stability of better than 0.2 dB. The mirrors, made from 10-/spl mu/m-thick single-crystal silicon and with a radius of 400-450 /spl mu/m, are able to tilt to 8/spl deg/ corresponding to 80% of touchdown angle. This is achieved using a nonlinear closed-loop control algorithm, which also results in a maximum actuation voltage of 85 V, and a pointing accuracy of less than 150 /spl mu/rad. This paper will describe the MEMS mirror and actuator design, modeling, servo design, and measurement results.     

新型埋入式长距离应变光纤传感器研制及性能研究

基于布里渊散射的分布式光纤传感技术可检测长距离光纤沿线的分布式应变和温度,非常适用于结构健康监测.但如何保证传感光纤在铺设及后期监测过程中的安全性是其应用于土木工程领域的关键问题.介绍了一种新型埋入式长距离光纤传感器的研制方法,首先在结构施工过程中根据监测网设计预埋微管,再通过气吹技术将传感光纤铺设至微管内部,最后利用...     

Tracking and disturbance rejection for fully actuated mechanical systems

In this paper, we solve the tracking and disturbance rejection problem for fully actuated passive mechanical systems. We assume that the reference signal r and its first two derivatives are available to the controller and the disturbance signal d can be decomposed into a finite superposition of sine waves of arbitrary but known frequencies and an arbitrary L² signal. We combine the internal model principle with the ideas behind the Slotine-Li adaptive controller. The internal model-based adaptive controller that we propose causes the closed-loop state trajectories to be bounded, and the tracking error and its derivative to converge to zero, without any prior knowledge of the plant parameters. An important part of our results is that we prove the existence and uniqueness of the state trajectories of the closed-loop system.     

新型光学加速度传感器动力学性能设计

针对一种新型光学加速度传感器设计了一种简单实用的微弹性机械结构,它是通过MEMS工艺在硅片上加工出来。通过能量法和有限元模拟法(ANSYS 8.0)对弹性臂的弹性系数和动力学振动系统的一阶固有频率进行了分析与模拟,根据传感器的性能要求选取了微弹性机械结构的参数,并对传感器的性能进行了分析模拟。结果表明:设计是合理可行的,根据参数确定传感器的量程约为±395 m/s2,测量频率约为1~4.5 kHz。     

Fabrication of a mechanical antireflection switch forfiber-to-the-home systems

We present the methods used to fabricate a micromechanical silicon optical modulator for use in a fiber-to-the-home applications. We emphasize the efforts made to realize a practical, robust, manufacturable, and easily packaged device. In addition, recent speed, temperature stability, and reliability results are presented. Rise and fall times of 132 and 125 ns, respectively, have been observed in response to a square wave drive signal. The device has been temperature cycled from -50°C to 90°C and shown greater than 10-dB optical contrast ratio over this temperature range. Finally, the device has been cycled at 500 kHz for a period of nearly two months (two-trillion cycles) without a noticeable loss in performance     

A review of magnetic actuation systems and magnetically actuated guidewire- and catheter-based microrobots for vascular interventions

Magnetic actuation techniques and microrobots have attracted considerable interest due to their potential applications in biomedicine. Interventional techniques have emerged as a minimally invasive approach to treat a wide range of vascular diseases. The current practice of interventional procedures is, however, limited by manual control of interventional devices and time-consuming procedures. Moreover, fluoroscopy is considered as an essential part of the procedure today despite posing many limitations for patients and physicians. Recently, various microrobotic solutions have been proposed for vascular interventions, including advances in magnetic navigation systems and magnetically steerable catheters and guidewires, which have shown potential benefits such as reduced radiation doses, improved access to difficult-to-reach and tortuous anatomy. This paper reviews the commercial magnetic actuation systems and magnetically actuated interventional microrobots that have been developed by academic research groups and medical companies worldwide, outlining their capability, applicability as well as limitations. We further address the challenges and future prospects of the research toward clinical acceptance of magnetic interventional technologies.

     

Design enhancement of a chevron electrothermally actuated microgripper for improved gripping performance

In this paper design modifications are proposed in microgripper design using two in-plane chevron electrothermal actuators. The design modifications are, converting free–free gripping arm into a clamped-free gripping arm and inclusion of the heat sinks in the shuttle. The modified design provides reduced temperature at the gripping jaws and higher gripping force. The proposed microgripper is modelled analytically and numerically using MEMS CAD tool CoventorWare. The performance of the microgripper such as displacement, force and temperature for the voltage range of 0–1.2 V is evaluated through numerical and analytical simulation. The results demonstrate the feasibility of fabrication. Further the gripper is made of polysilicon which allows operating the gripper at lower voltage.     

Linearization of electrostatically actuated surface micromachined2-D optical scanner

This paper presents an effective method of linearizing the electrostatic transfer characteristics of micromachined two-dimensional (2-D) scanners. The orthogonal scan angles of surface micromachined polysilicon scanner are controlled by using quadrant electrodes for electrostatic actuation. By using a pair of differential voltages over a bias voltage, we could improve the distortion of projected images from 72% to only 13%. A theoretical model has been developed to predict the angle-voltage transfer characteristics of the 2-D scanner. The simulation results agree very well with experimental data. Differential voltage operation has been found to suppress the crosstalk of two orthogonal scan axes by both experiment and theoretically. We have found that a circular mirror is expected to have the lowest angular distortion compared with square mirrors. Perfect grid scanning pattern of small distortion (0.33%) has been successfully obtained by predistorting the driving voltages after calibration     

新颖交流开关变换器的建模和仿真分析

开关电源是一个非线性系统,它的分析与设计一直是一个难题。本文对在开关电源方面应用较多的状态空间平均法进行了数学推导,结合MATLAB软件对新颖交流升降压变换器（Buck-Boost）建立了电路模型、数学模型和电路分析法模型,并进行了仿真对比,定量的讨论了状态空间平均法的适用条件,说明状态空间平均法的本质,并用其分析了开关频率对于输出电压纹波的影响。     

Motion and structure interpretation of an optical switch

This paper focuses on tracking, reconstruction and motion estimation of a well-defined MEMS optical switch from a microscopic view. For out-of-view reconstruction, a homography capable of transforming feature points and feature lines between a microscopic image and a CAD model of the switch is implemented. The homography between two sequential microscopic images is decomposed and factorized for motion estimation. Optical flow has also been explored to provide rough estimations of rotation centre and angle. The paper also illustrates motion parameter optimization principles to deal with uncertainty inherent in micro world. After non-linear optimization, estimation accuracy for rotation angle and rotation centre can reach 0.06° and pixel level, respectively.     

Research progresses of SOI optical waveguide devices and integrated optical switch matrix

1Introduction Dense wavelength division multiplexing(DWDM)is the most powerful method to upgrade the transmission capacity of the optical fiber transmission system.In DWDM system,the enormous available bandwidth is utilized by multiplexing laser beams with different wavelength in one single fiber.With DWDM technology,parallel transmission of data streams with different format leads to high speed information communication,thereby reduces the requirement for the high speed electronic device…     

Optical switch with auto-aligning fibers and latching micro-mirrors

This paper presents an innovative device for self-aligning in a V-groove and a self-latching vertical mirror on the suspension diaphragm using the out of plane fiber-optical switch array technique. The self-aligning offers integrating the optical fiber and mirror within the same optical switch. The self-latching vertical mirror is supported on the suspension diaphragm by four cantilever beams. The theoretical analysis includes a dynamic simulation using the ANSYS software and corner compensation using the IntelliCAD software. The fabrication process consists of wet etching micromachining, lithography, and excimer laser ablation. This proposed process is simpler than those proposed in other works. An electrostatic driving voltage is used to operate the optical switch. The mirror is made of a photoresist coating with gold film as the switching element. The reflectivity of the gold film mirror is higher than 85% using a wavelength of 1310 nm. The micro-optical switch has a maximum displacement of 48 m and the switching time is below 0.4 ms with a driving voltage of 100 VDC.This work was supported by the National Science Council (series no. NSC90-2218-E-005-005) and the Ministry of Economic Affairs of Taiwan. Thanks are due to the MIRLs colleagues at ITRI for preparing the etching solutions and operating the excimer laser.     

Numerical simulations on performance of MEMS-based nozzles at moderate or low temperatures

Performance of microelectromechanical systems (MEMS)-based nozzles at moderate and low temperatures is numerically analyzed using the direct simulation Monte Carlo method. Considering the intermolecular attractive potential caused by low temperature, the generalized soft sphere collision model is introduced. The Larsen–Borgnakke model for the generalized sphere model is used to model the energy exchange between the translational and internal modes. The results for nozzle flows at an initial temperature of 300 K show that the temperature behind the throat is quite low and the intermolecular attractive potential cannot be ignored. Different working conditions in two-dimensional (2D) nozzles are simulated using the present method, including exit pressure, inlet pressure, initial temperature, nozzle geometry, and gas species. The effects on the nozzle performance are analyzed. Simulations on flows in a three-dimensional (3D) low aspect ratio flat nozzle show that the increased surface-to-volume ratio, which leads to high viscosity dissipation, causes a much lower flow characteristic and performance comparing with the 2D case.     

A novel design and fabrication of a micro-gripper for manipulation of micro-scale parts actuated by a bending piezoelectric

In this study, a novel micro-gripper using a piezoelectric actuator was designed and improved by the design of experiments (DOE) approach. Using a bending PZT actuator connected to the micro-gripper by a rigid wedge can be considered as a novel approach in this field. Almost all of the similar grippers in this category were former actuated by a piezo-stack which has some limitations and difficulties like fabrication in MEMS proportions. The basic design was borrowed from compliant mechanisms that are suitable for MEMS application and easy to manufacture in micro-scale because of the intrinsic integration characteristic. Since stress concentration is common in flexure hinge compliant mechanisms, our focus was to consider strength as an important factor in our design. Finite element analysis tools were used to implement the DOE based on two criteria; minimizing stress concentration and maximizing the output displacement in the micro-gripper structure as much as possible with the consideration of the total size of the gripper. The experiment was performed to validate the simulation results and experiment results agreed well with the simulation one. The slight geometrical discrepancy in significant portions of structure like flexure hinges partially contributes to the accumulated error between the simulation and the experiments.