Design of tracking servo control system for holographic data storage

Holographic data storage is a strong candidate for the next generation archive storage device. However, disturbances such as external shock, vibration, flutter and eccentricity of the disk affects the holographic data storage device. Thus, tracking servo control is necessary in order to enhance the signal noise ratio and reduce the bit error rate and retrieve the data accurately. It is also inevitable to face track overlapping problem if there is no datum to apply servo control during the recording process. In this research, we suggest a method forming a holographic servo track to detect the tracking error signal continuously without using any additional laser diode or pre-format layer. The tracking servo controller is designed to improve the track following performance, and the validity of the proposed method is confirmed through experiments on our holographic data storage system.     

Minimax LQ stochastic tracking and servo problems

It is proved that the separation between feedback and feedforward of the two-degree-of-freedom linear quadratic (LQ) stochastic controller reported by E. Mosca and G. Zappa (ibid., vol.34, p.240-2, 1989) can be suitably extended, when a linear controller is postulated, to the minimax LQ stochastic tracking and servo problems. Besides the relevance of the results, the authors show that in some problems the Wiener and the H_∞ approaches can play a fruitful complementary role     

基于舵机的户用太阳自动跟踪装置

采用全电路控制双轴光电跟踪方式,并以舵机连锁作为机械驱动机构,设计了一种小型的户用太阳自动跟踪装置。本装置机械结构简单,便于安装;跟踪灵敏度高,成本很低;装有西限位开关,使跟踪装置在傍晚光线变暗时自动返回到初始状态,便于次日跟踪。实际使用及测试结果表明,安装本装置可使太阳能电池板平均发电效率提高38.7%。     

基于DSP与FPGA的跟踪伺服运动控制器设计

在分析光电跟踪伺服系统特点的基础上,以TI公司DSP芯片TMS320F2812作为主控制芯片,采用FPGA进行逻辑时序控制,设计了基于DSP和FPGA的多轴伺服运动控制器。给出了该控制器的功能和硬件结构以及软件流程设计。实验结果表明,该控制器具有高集成度、灵活性、实时性、模块化的特点,完全满足了在复杂环境下对伺服系统控制的要求。     

Homography-based visual servo tracking control of a wheeled mobile robot

A visual servo tracking controller is developed in this paper for a monocular camera system mounted on an underactuated wheeled mobile robot (WMR) subject to nonholonomic motion constraints (i.e., the camera-in-hand problem). A prerecorded image sequence (e.g., a video) of three target points is used to define a desired trajectory for the WMR. By comparing the target points from a stationary reference image with the corresponding target points in the live image and the prerecorded sequence of images, projective geometric relationships are exploited to construct Euclidean homographies. The information obtained by decomposing the Euclidean homography is used to develop a kinematic controller. A Lyapunov-based analysis is used to develop an adaptive update law to actively compensate for the lack of depth information required for the translation error system. Experimental results are provided to demonstrate the control design.     

基于自适应模糊PID控制的太阳光跟踪伺服系统

针对太阳光跟踪伺服系统中传统PID控制过程中的一些问题,通过对自适应模糊PID控制系统的分析,设计了一种双轴跟踪伺服系统自适应模糊PID控制器,同时在Simulink环境中建立了方位角跟踪传动机构仿真模型并完成了仿真。仿真结果表明,太阳光跟踪伺服系统自适应模糊PID控制器较传统PID控制器具有较强的稳定性、适应性与鲁棒性,在太阳光跟踪伺服系统控制领域具有重要的实用价值与应用空间。     

Real-time dynamic gesture recognition and hand servo tracking using PTZ camera

Multimedia Tools and Applications - A technology of real-time dynamic gesture recognition and hand tracking using a Pan-Tilt-Zoom (PTZ) camera was presented in this study. It was aimed to achieve...     

End-effector trajectory tracking of flexible link parallel robots using servo constraints

Multibody System Dynamics -     

基于DSP与CAN总线的跟踪伺服控制器设计

在分析跟踪伺服系统特点的基础上,以TI公司DSP芯片TMS320F2812作为主控制芯片,采用CAN总线与上位机通信,设计了基于DSP与CAN总线的多轴跟踪伺服运动控制器。给出了该控制器的功能和硬件结构,以及软件流程设计。实验结果表明,该控制器具有高集成度、灵活性、实时性、模块化的特点。     

基于DSP和ARM的光电跟踪系统伺服控制器设计及实现

针对光电跟踪系统伺服控制高精度、高实时性的要求,设计了一种基于TMS320F2812DSP和LPC2214ARM嵌入式微处理器的双CPU伺服控制器,利用LPC2214完成外设数据的采集和预处理、外设的管理、系统时序协调、人机接口等功能,DSP实现电机控制算法.详细介绍了控制器结构和主要硬件模块,并给出了软件设计流程.野外跟踪试验结果表明设计系统能够快速准确地跟踪预定运动目标,达到了系统的设计要求.     

A new improved continuous variable structure controller for accurately prescribed tracking control of BLDD servo motors

A new improved robust variable structure controller is presented to provide an accurately prescribed tracking performance for brushless direct drive (BLDD) servo motors (SM) under uncertainties and load variations. A special integral sliding surface suggested for removing the reaching phase problems can define its ideal sliding mode and virtual ideal sliding trajectory from an initial position of SM. The tracking error caused by the nonzero value of the sliding surface is derived. A corresponding continuous control input with the disturbance observer is suggested to track a predetermined virtual ideal sliding trajectory within a prescribed value under all the uncertainties and load variations. The usefulness of the proposed algorithm is demonstrated through the comparative simulations for a BLDD SM under load variations.     

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.     

High-aspect-ratio photolithography for MEMS applications

High-aspect-ratio photolithography using a commercially available positive photoresist and a conventional contact mask aligner with standard UV light source is described. A multiple coating process is developed to obtain a photoresist thickness up to 23 μm while maintaining a smooth photoresist surface. Intimate contact between the mask and wafer is found to be most critical for high-resolution photolithography. Vacuum contact is found to be well-suited for this purpose. Additionally, edge bead removal is found to be of significant importance for intimate contact between the mask and the substrate. Prebake, exposure, and development conditions are optimized for resolution and aspect ratio. Maximum prebake temperature still allowing the photoresist to be developed is found to be the optimal temperature for obtaining high resolution. Prebake time distribution is optimized for avoiding residual stress in the photoresist, as well as maintaining high resolution, when multiple coating is applied. Minimum linewidth and spacing of 3.5 μm and 2.5 μm, respectively, and a maximum aspect ratio of 7.7 have been achieved in a photoresist thickness of 23 μm. Postbake improves the chemical resistance to subsequent processes, for example, electroless nickel plating using the photoresist as a mold. However, postbake also causes pattern distortion, which can be severe at times. Therefore, optimal process and design conditions for minimizing the pattern distortion have been studied     

Multi-robot multiple hypothesis tracking for pedestrian tracking

In this paper the problem of tracking walking people with multiple moving robots is tackled. For this purpose we present an adaptation to the Multiple Hypothesis Tracking method, which unlike classic MHT, allows for one-to-many associations between targets and measurements in each hypothesis production cycle and is thus capable of operating in a scenario involving multiple sensors. Derivation of hypotheses probabilities accounts for the continuously changing overlapping areas in fields of view of the robots sensors and for detection uncertainty. In the context of three experiments involving people walking among moving robots, the successful integration of our tracking algorithm to a real-world setup is assessed.     

直线伺服同步传动的H∞控制

研究直线伺服系统位置同步传动的H∞控制问题,以2台直线电机作为高速度、高精度龙门移动式镗铣床的龙门柱纵向进给的传动机构为应用背景,提出一种同步传动H∞控制方案.该方案将同步传动的2台电机看作一个整体被控对象,由H∞反馈控制器保证同步精度.仿真结果表明了所提出方案的合理性和有效性.     

Dynamic meniscus models for MEMS elements

The dynamics of a liquid meniscus bridge between solid surfaces were analyzed based on the continuum lubrication theory assuming a small vibration of the spacing. The geometry of the meniscus considered in this study was the finite meniscus ring. The following two meniscus models were considered: (1) the fixed boundary position of the meniscus and variable contact angle (VCA) model and (2) the fixed contact angle and variable boundary position (VBP) model. The time-dependent Reynolds equation was solved under the boundary condition considering the Laplace pressure, assuming that the mass of the liquid in the meniscus is conserved. It was found by linearization that the pressures and the load-carrying capacities of both models have three terms, i.e., a time-dependent squeeze term due to the viscosity of the liquid, a spring term due to the dynamic Laplace pressure and a static meniscus force term. The comparisons between these models and experimental results were also presented.     

Flip chip packaging for MEMS microphones

We have developed a microphone package using flip chip technology instead of chip and wire bonding to create smaller MEMS microphones. With this new packaging technology the transducer chip and an ASIC chip are flip chip bonded on a ceramic substrate. The package is sealed by a polymer foil laminated over the chips and by a metal layer. The sound port is on the bottom side in the ceramic substrate. In this paper the packaging technology is explained in detail and results of electro-acoustic characterization and reliability testing are presented. We will also explain the way which has led us from the packaging of Surface Acoustic Wave (SAW) components to the packaging of MEMS microphones.     

Hybrid postprocessing etching for CMOS-compatible MEMS

A major limitation in the fabrication of microstructures as a postCMOS (complimentary metal oxide semiconductor) process has been overcome by the development of a hybrid processing technique, which combines both an isotropic and anisotropic etch step. Using this hybrid technique, microelectromechanical structures with sizes ranging from 0.05 to ~1 mm in width and up to 6 mm in length were fabricated in CMOS technology. The mechanical robustness of the microstructures determines the limit on their dimensions. Examples of an application of this hybrid technique to produce microwave coplanar transmission lines are presented. The performance of the micromachined microwave coplanar waveguides meets the design specifications of low loss, high phase velocity, and 50 Ω characteristic impedance. Various commonly used etchants were investigated for topside maskless postmicromachining of 〈100〉 silicon wafers to obtain the microstructures. The isotropic etchant used is gas-phase xenon difluoride (XeF₂), while the wet anisotropic etchants are either ethylenediamine-pyrocatechol (EDP) or tetramethylammonium hydroxide (TMAH). The advantages and disadvantages of these etchants with respect to selectivity, reproducibility, handling, and process compatibility are also described