基于改进Smith预估器的显微视觉伺服

针对视觉延迟的问题,提出采用改进的Smith预估器(MSP)来改善视觉伺服系统的控制品质。在对基于位置的动态"look-and-move" 视觉伺服系统特性分析的基础上,建立了基于MSP视觉伺服系统的结构,同时建立了视觉伺服系统的分时模型。在微操作机器人平台上进行了点到点、抗干扰和微齿轮的跟踪抓取实验。结果表明,与只有PID控制器的视觉伺服系统相比,带MSP的视觉伺服系统具有更好的控制品质。克服了由于图像采集、传输和处理导致的视觉伺服延迟而严重影响控制系统的品质局限,并克服了传统方法通过减小系统增益来增强系统的鲁棒性,但同时降低了系统响应特性的缺点。     

激光微束对球状介质粒子光阱力的计算与仿真分析

基于几何光学原理,以射线光学计算模型为基础,对几何尺寸远大于光波长的米氏球状粒子所受轴向光阱力进行了计算。在给定参量条件下,进行了数值仿真,并根据仿真结果,讨论了光束束腰半径、相对折射率、激光波长及功率等系统主要参量与光阱品质特性的关系。这些参量都是由显微镜和其他一些光学部件的特性所决定的。针对不同介质粒子合理选择上述参量,以得到较大光阱力和光阱刚度。这些仿真结果为各仪器参量的选择提供了理论依据。     

阵列光镊的发展

介绍了光镊的原理及近年来发展起来的各种阵列光镊技术,探讨了阵列光镊技术在不同学科领域的应用.     

Biomechanical properties of single chondrocytes and chondrons determined by micromanipulation and finite-element modelling

A chondrocyte and its surrounding pericellular matrix (PCM) are defined as a chondron. Single chondrocytes and chondrons isolated from bovine articular cartilage were compressed by micromanipulation between two parallel surfaces in order to investigate their biomechanical properties and to discover the mechanical significance of the PCM. The force imposed on the cells was measured directly during compression to various deformations and then holding. When the nominal strain at the end of compression was 50 per cent, force relaxation showed that the cells were viscoelastic, but this viscoelasticity was generally insignificant when the nominal strain was 30 per cent or lower. The viscoelastic behaviour might be due to the mechanical response of the cell cytoskeleton and/or nucleus at higher deformations. A finite-element analysis was applied to simulate the experimental force-displacement/time data and to obtain mechanical property parameters of the chondrocytes and chondrons. Because of the large strains in the cells, a nonlinear elastic model was used for simulations of compression to 30 per cent nominal strain and a nonlinear viscoelastic model for 50 per cent. The elastic model yielded a Young''s modulus of 14 ± 1 kPa (mean ± s.e.) for chondrocytes and 19 ± 2 kPa for chondrons, respectively. The viscoelastic model generated an instantaneous elastic modulus of 21 ± 3 and 27 ± 4 kPa, a long-term modulus of 9.3 ± 0.8 and 12 ± 1 kPa and an apparent viscosity of 2.8 ± 0.5 and 3.4 ± 0.6 kPa s for chondrocytes and chondrons, respectively. It was concluded that chondrons were generally stiffer and showed less viscoelastic behaviour than chondrocytes, and that the PCM significantly influenced the mechanical properties of the cells.     

Micropositioning and microscopic observation of individual picoliter-sized containers within SU-8 microchannels

We describe the fabrication and application of a bioanalytical chip, made of SU-8 photoresist, comprising integrated, high aspect-ratio microfluidic channels, suitable to manipulate and investigate vesicles, cell fragments and biological cells. A central micrometer-sized aperture allows electrical particle counting and planar membrane experiments, microfluids allow (sub)micrometer-sized objects to be transported and addressed with different chemicals. Here we show how lipid vesicles are positioned with micrometer precision within the micro-channels by means of pressure and electrophoretic movement. Our approach is suited for controlling and investigating (bio)chemical synthesis and cellular signalling processes in ultrasmall individual vesicles by electro-optical techniques.     

基于规范化谱主成份分析的微操作深度信息提取

针对微操作工具在测试窗口内（X-Y平面）大范围移动时，采集到的模糊图像差异较大的问题，提出了一种新的不变量特征提取方法――规范化谱图像，将其应用于深度估计可提高系统的鲁棒性。同时，利用主成份分析方法可降低数据的维数并抑制噪声的影响，使得系统的实时性和精度得到较大改善。实验结果验证了上述方法的有效性。     

微操作中力的检测及控制

微操作过程中,操作对象的特征尺寸通常小于1 mm。由于尺度效应和表面效应,操作对象本身的重力和惯性力不再起主导作用,粘附力作用成为影响微操作成败的关键因素。这就导致了单靠宏观上的操作技术不能充分解决微观领域操作问题。该文在论述微操作过程中粘附力作用机理的基础上给出了一些微操作过程中有关力的检测、控制的可行方法。     

集成式五维微力/力矩传感器的研究

五维微力 /力矩传感器应用于微装配机器人操作末端的微力觉感知 ,能够同时测量三个方向的微力Fx、Fy、Fz 和两个方向的微力矩Mx 和My;测力量程± 1N ,测力矩量程± 0 .0 5N·m ;放大电路集成在传感器的本体中。应用力学理论对本体进行理论分析 ,推导出计算公式 ,求出本体的应变 ;并采用有限元分析软件进行仿真 ,分析应变 ,确定了一种适用的静态非线性标定方法     

组合式微夹持器控制系统的研制

将微直线电机宏动机构与双晶片压电悬梁微动机构结合,研制高精度、大范围的组合式微夹持器．针对宏微结合的结构形式,设计组合式微夹持器宏微控制系统。采用仿人智能PI控制方法,提高了控制精度。测试实验表明,闭环控制系统取得较好效果．     

Physical,structural, and mechanical characterization of calcium–shellac microspheres as a carrier of carbamide peroxide

Calcium–shellac microspheres with encapsulated carbamide peroxide (CP) were made by emulsification to generate an emulsion including shellac ammonium salt aqueous solution with soluble CP dispersed in sunflower oil with calcium chloride powders, followed by gelation between shellac and calcium. The effects of formulation and processing conditions on the encapsulation efficiency of CP, the physical, structural, and mechanical properties of calcium–shellac microspheres, including size, inner structure, and mechanical strength, were investigated. The sizes of the prepared microspheres were in the range of 10–100 μm, depending on the agitation speed used in the emulsification process. The morphology of calcium–shellac microspheres was characterized using scanning electron microscopy and image analysis. Their inner structure was evaluated using X‐ray microcomputed tomography, and their mechanical strength was determined by a micromanipulation technique. The structure and mechanical strength of the microspheres were compared with those bigger calcium–shellac beads (1–3 mm in diameter) made by extrusion followed by gelation (Xue and Zhang, J Microencapsul 2008, 25, 523), and clear contrast in the properties between the two preparation methods has been found. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009