Integrated metallic gauge in a piezoelectric cantilever

In this study, a self-sensitive piezoelectric cantilever with a new design for sensing is presented. Micro-cantilevers were actuated by a 120 nm-thick Lead Zirconate Titanate Oxide (PZT) layer. Detection was done by measuring the resistance of a metallic gauge integrated on the surface of the micro-piezoelectric cantilevers. Some metallic gauges were embedded in a Wheatstone bridge to improve the measured resistance accuracy. Devices with direct resistance measurement were also realized. Gauge resistance responses were compared with an optical measurement by a White Light Interferometer. By biasing the PZT between −5 V and 5 V, cyclic deflection of the cantilever was detected with both optical and metallic gauge resistance systems. The two measurements fit. This self-sensitive piezoelectric cantilever can be used for fatigue test with packaged devices.     

基于静电力的微液滴驱动芯片

为了精确操控微流体,设计并制作了一种基于静电力的微液滴驱动芯片.介绍了驱动原理和工艺流程,搭建了驱动检测实验平台.芯片采用开放式的结构,只需单层共平面控制电极,以硅作衬底,氧化硅和多晶硅作绝缘层,重掺杂多晶硅为驱动电极阵列,高质量Si3N4作介质层,碳氟聚合物为疏水层.实验表明:微液滴可在芯片上按程序设定方式在二维平面...     

微小尺度射流流量传感器的设计与仿真分析

在许多新型传感器和微系统中均存在微量流体自动、精确地驱动和控制问题,而这有赖于微小尺度下对流量的精确测量。基于射流振荡原理设计了一种新型的无反馈通道微小尺度流量传感器,采用计算流体动力学(CFD)方法对该流量传感器的测量特性进行了仿真研究。通过观测振荡腔内部流场,分析了振荡器内部流动形态和射流振荡过程。通过对监测点压力变化曲线的分析,获得了不同入口速度下流体振荡频率,建立了流体流速与振荡频率的函数关系。研究结果表明,该微小尺度射流振荡器振荡平稳,主射流切换灵活,在较宽的流速范围内,流速与振荡频率具有线性关系,具有0.3%的较低的相对压力损失并可达到较小的测量下限,易于加工成型。     

Design and testing of micro fluidic chemical analysis chip integrated with micro valveless pump

Micro fluidic analysis technology has been developed rapidly since the 1990s. The essentials of the technology are fabricating the micron structure (usually net channels, 20―100 μm wide and 10―30 μm deep) in chips by micro processing, and analyzing the fluids of samples or reagents chemically when they are controlled to flow and to be mixed in the micro structures. The occurrence of the technology makes the miniaturiza-tion, integration and portability of chemical detecting devices possibl…     

高精度压电步进直线驱动器

提出一种以压电叠堆为驱动动力源的新型精密直线驱动器方案。定子采用柔性铰链双侧对钳方式交替对动子起到钳位作用。对驱动器工作原理进行了分析研究,建立了机械系统的数学模型。采用MSC Patran/Nastran软件对机械结构进行了仿真分析,并对所开发的驱动器样机进行了实验测试。测试结果与理论分析结果基本相符,样机的运动速度可达1.52mm/m in、单步最小位移(运动分辨率)为3.35 nm。驱动器性能稳定可靠,可望在精密工程等相关领域得到应用。     

新型推挽激励的谐振式微机械静电场传感器

为了提高传感器的信噪比(signal-to-noise ratio,SNR),降低器件的耦合干扰,基于表面微机械工艺设计制作了一种新型推挽激励方案的谐振式微型静电场传感器.该传感器敏感结构主要包括静电梳齿激励电极、屏蔽电极和感应电极3部分.工作时,在该传感器敏感结构同一侧梳齿的固定端上加入反相相等的激励信号,实现差分激励,使屏蔽电极在谐振频率处振动,从而在感应电极上感应出差分电流信号,通过相关检测方式检测出传感器该输出信号的二次谐波分量,即可获得被测静电场强度大小.该传感器的新型结构设计和激励检测方案可获得最大电场响应灵敏度,并有效抑制了同频耦合串扰和共模噪声.常压室温(约25℃)测试结果表明,在量程(-15 kV/m～15 kV/m)内,只需要5 Vpp激励电压,其中线性度(端基线性度)达到了1.03%,分辨率优于200 V/m.     

小口径电子水表技术现状及发展趋势

该文描述与分析目前国内外小口径电子水表(如射流水表、超声水表、电磁水表等)产品的现状及特点,对电子水表的技术发展趋势作了研究与讨论,同时提出应关注电子水表传感与信号处理的共性关键技术与个性关键技术的同步发展、重视采用现代先进设计理念、方法与手段进行电子水表的研究与开发的观点。     

膝踝协调驱动的平面双足机器人短跑运动规划

本文采用虚拟力控制方法规划双足机器人动态稳定的短跑运动,以解决仅脚尖着地时无有效支撑域的问题.然而,脚尖着地的方式却给支撑腿引入了1个冗余关节,导致在虚拟力控制时支撑腿内部运动的不确定.为解决该问题,在分析身体虚拟力和支撑腿各关节做功的基础上,以最大化虚拟力总驱动功率为目标,提出膝关节和踝关节协调驱动的条件和实现方法.该方法通过均衡膝和踝的驱动负担,既解决了支撑腿内部运动的不确定问题,又充分发挥了踝关节的驱动能力.在腿部其他关节驱动能力不变的情况下,通过短跑运动方式可以有效提高双足机器人的运动速度.最后,通过仿真实验验证了本方法的有效性.     

Visualization of Fatigue Cracks at Structural Members Using a Pulsed Laser Scanning System

In this research, a noncontact nondestructive testing (NDT) method is proposed to detect the fatigue crack and to identify the location of the damage. To achieve this goal, Lamb wave propagation of a plate-like structure, which is induced by scanning laser source actuation system, is analyzed. A ND:YAG pulsed laser system is used to generate Lamb wave exerted at the multiple points of a steel coupon, and a piezoelectric sensor is installed to measure the structural responses. Multiple time signals measured by the piezoelectric sensor are aligned along the vertical and horizontal axes corresponding to laser impinging points so that 3-dimensional data can be constructed. Then, the 3-dimensional data is sliced along the time axis to visualize the wave propagation. The scattering of Lamb wave due to the damage can be described in the wave propagation image, and hence the damage can be localized and quantified. Damage-sensitive features, which are reflected wave from the damage, are clearly extracted by wave-number filtering based on the 3-dimensional Fourier transform of the visualized data. Structural members with fatigue cracks are investigated to verify the effectiveness and the robustness of the proposed NDT approach.     

Robust nonlinear control of a variable-pitch quadrotor with the flip maneuver

This paper presents robust nonlinear control of a variable-pitch quadrotor with the flip maneuver. Backstepping approach is chosen for nonlinear control design. A control allocation loop dynamically computes the blade pitch angle of each rotor. A systematic method to select controller gains is presented that ensures closed-loop stability. Detailed analysis of the flip maneuver in the presence of input saturation is presented for the first time. Performance of the proposed control law is first verified through simulation. This is then implemented on a PixHawk open source autopilot board and flight tests are performed on an off-the-shelf variable-pitch quadrotor frame.