扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构

在进行理论分析证实可行性和模拟仿真优化参数后,利用非硅表面微加工方法中的牺牲层工艺制备了一种扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构.该双稳态结构尺寸为1.9mm×1.6mm×0.03mm,通过永磁力实现稳态姿态无功耗保持,通过对其单侧触点施加纵向驱动力使之达到30μm的纵向驱动位移,可以实现机构的双稳态姿态切换,可以通过控制永磁体磁片、悬臂梁和扭梁的尺寸来灵活调控稳态切换所需的驱动力矩.此双稳态机构可与电磁驱动、电热驱动和静电驱动等类型的微驱动器联用构成永磁双稳态MEMS微继电器.     

扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构

在进行理论分析证实可行性和模拟仿真优化参数后,利用非硅表面微加工方法中的牺牲层工艺制备了一种扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构.该双稳态结构尺寸为1.9mm×1.6mm×0.03mm,通过永磁力实现稳态姿态无功耗保持,通过对其单侧触点施加纵向驱动力使之达到30μm的纵向驱动位移,可以实现机构的双稳态姿态切换,可以通过控制永磁体磁片、悬臂梁和扭梁的尺寸来灵活调控稳态切换所需的驱动力矩.此双稳态机构可与电磁驱动、电热驱动和静电驱动等类型的微驱动器联用构成永磁双稳态MEMS微继电器.     

含非线性缺陷的光子晶体异质结构中的光学响应

为了得到非线性介质中的光学响应,考虑了光通过含有非线性缺陷的一维光子晶体异质结构的情况,对缺陷层的介电函数采取δ函数近似的方法,得到了具有非线性缺陷的一维光子晶体异质结构中的光学响应表达式。结果表明,非线性缺陷存在时,在光学响应中会出现双稳态、多稳态等特性。讨论了双稳态及其多稳态的形成条件,并与考虑缺陷层厚度时的结论进行了比较,为构造零阈值的激光器和非线性光学器件的初步设计提供了有益的理论参考。     

一种新型平面并联定位机构的误差建模与分析

当前IC行业的迅速发展使得研制新型高速精密定位机构成为十分迫切的任务.针对这种需要,提出了一种新型平面并联定位机构,它由直线电机直接驱动含有平行四边形支链的并联杆机构来实现末端平台平面内的平动.首先根据输入、输出关系微分法建立了机构的误差模型,并对影响末端位姿误差的各类几何误差源进行了敏感性分析,给出了误差源对末端精度的敏感系数;然后基于误差映射矩阵,推导了机构定位误差极值表达式,并给出了已知误差源精度水平下,平台定位误差在工作空间内的分布情况.上述误差建模与分析方法对高精度的定位机构的设计及误差补偿具有重要的指导意义.     

液晶(EBBA)光学双稳态及其温度关系

本文从理论和实验上研究了平行平面排列的向列型液晶在光场作用下的重取向及由其产生的非线性光学现象、光学双稳态和多稳态特性。观察了光通过液晶时产生的“光自聚焦”现象,并首次观察到“光自发散”现象,对二者进行理论解释,前者归结δε=ε∥-ε⊥>0,而后者为δε<0。     

一种新的混合型光学双稳器件与基本光逻辑门的实现

本文报导了一种用雪崩型异质结光晶体管和半导体激光器组成的新型光学双稳态器件。由于该器件利用光晶体管内部的光电双稳性,因此具有结构简单,调整方便,便于集成。文中讨论了该双稳器件稳态工作的四种工作模式。当其工作在光学双稳态模式时,最小临界触发光功率<10μW;高态输出     

双稳态孤子

对于具有一定形式非线性的薛定谔方程，存在单孤子解的多稳态，也就是说对于相同能量，单孤子具有不同的传输常数．本文以一非线住形式Ｌｉｎｅａｒ　Ｓｍｏｏｔｈ　Ｓｔｅｐ（ＬＳＳ）函数为例，对孤子的双稳态进行理论分析，并对其双稳态的光学转换进行数值模拟．     

一种新型球面并联分选机构运动学研究

提出一种新型3自由度并联机构来解决LED分选机的高速分选问题。首先研究了该机构自由度,该机构能提供3个方向上的纯转动;再结合自由度性质分析,建立了约束方程,进行运动学的正反解分析;使用Newton迭代的方法求得各位置点具体的运动参数,并分析了求解过程中的多解问题,及相关处理方法,最后给出相应的算例。通过实例分析数据可知:随着执行机构目标位置的变化,能实时求解出个各曲柄相对于基座的转角,且当2个曲柄转角增大时,第3个曲柄转角一定减小,符合实际的运动规律。     

白噪声激励下双稳态压电发电系统的响应分析

研究了白噪声激励下双稳态压电发电系统的响应特性。首先利用蒙特 卡罗法模拟高斯白噪声;然后利用数值模拟和实验的方法分别分析了噪声强度、负载阻抗和初始值对系统响应特性的影响。得到了噪声强度的增加会减少双稳态系统两个稳定平衡点之间的跳跃时间。通过给出大幅运动的吸引域说明初始值会影响系统的运动状态,从而影响输出功率,当电阻为19.1 kΩ时,输出功率最大。     

白噪声激励下双稳态压电发电系统的响应分析

研究了白噪声激励下双稳态压电发电系统的响应特性。首先利用蒙特-卡罗法模拟高斯白噪声;然后利用数值模拟和实验的方法分别分析了噪声强度、负载阻抗和初始值对系统响应特性的影响。得到了噪声强度的增加会减少双稳态系统两个稳定平衡点之间的跳跃时间。通过给出大幅运动的吸引域说明初始值会影响系统的运动状态,从而影响输出功率,当电阻为19.1kΩ时,输出功率最大。     

New polarized electromagnetic actuators as integrated mechatronic components — design and application

This paper presents an overview over the computer-aided design process of mechatronic devices and systems, especially the design of electrodynamic and electromagnetic drives using modern high-energy permanent magnetic materials like NdFeB and SmCo. This paper also presents some examples of such actuators. The first example is a miniaturized pneumatic valve for industrial applications. This valve has an integrated bi-stable polarized solenoid actuator. The second example is a polarized electromagnetic valve manufactured by modern batch technologies using photo-structurable glass material. The valve seat and the actuator coils are realized using this glass material. The third example is a gripping device with compliant mechanism and planar moving coil actuator.     

Design of Compliant Mechanisms: Applications to MEMS

Compliant mechanisms are single-piece flexible structures that deliver the desired motion by undergoing elastic deformation as opposed to jointed rigid body motions of conventional mechanisms. Compliance in design leads to jointless, no-assembly (Fig. 1), monolithic mechanical devices and is particularly suited for applications with small range of motions. The compliant windshield wiper shown in Fig. 1 illustrates this paradigm of no-assembly. Conventional flexural mechanisms employ flexural joints that connect relatively rigid links as depicted in Fig. 2. Reduced fatigue life, high stress concentration and difficulty in fabrication are some of the drawbacks of flexural joints. Our focus is on designing compliant mechanisms with distributed compliance which employs flexural links (see Fig. 3) and have no joints (neither pin nor flexural joints) for improved reliability, performance, and ease of manufacture. Distributed compliant mechanisms derive their flexibility due to topology and shape of the material continuum rather than concentrated flexion at few regions. This paper focuses on the unique methodology employed to design jointless mechanisms with distributed compliance. The paper also illustrates a compliant stroke amplification mechanism that was recently designed, fabricated and tested for MEMS application.     

Experimental validation of the kinematic design of 3-PRS compliant parallel mechanisms

In this paper, a procedure for the kinematic design of a 3-PRS compliant parallel manipulator of 3 degree of freedom is proposed. First, under the assumption of small displacements, the solid body kinematics of the 3-PRS has been studied, performing a comprehensive analysis of the inverse and forward kinematic problem, and calculating the rotations that the revolute and spherical flexure joints must perform. Then, after defining some design requirements and therefore the necessary displacements to fulfill, a design process based on the finite element calculations has been stablished, giving the necessary guidelines to reach the optimal solution on a 3-PRS compliant mechanism. Also, a prototype has been tested, using a coordinate measuring machine to verify its dimensions and the resulting displacements in the end effector and the actuated joints. Finally, those measurements have been compared with the FEM and the rigid body kinematics predictions, contrasting the validity of those two modelling approaches for the kinematic design of compliant mechanisms.     

Automated Characterization and Compensation for a Compliant Mechanism Haptic Device

Compliant mechanisms and voice coil motors can be used in haptic device designs to eliminate bearings and achieve smooth friction-free motion. The accompanying return-to-center behavior can be compensated using feedforward control if a suitable multidimensional stiffness model is available. In this paper we introduce a method for automatic self-characterization and compensation, and apply it to a planar haptic interface that features a five-bar compliant mechanism. We show how actuators and position sensors already native to typical impedance-type haptic devices can readily accommodate stiffness compensation. Although a portion of the motor torque is consumed in compensation, the device achieves smooth friction-free articulation with simple, low tolerance, and economic components. Empirical models built on self-characterization data are compared to standard empirical and analytical models. We produce a model by self-characterization that requires no inversion and is directly useable for compensation. Although our prototype compliant mechanism, which we fabricated in plastic using fused deposition modeling, exhibited hysteresis (which we did not compensate), the return-to-center behavior was reliably reduced by over 95% with feedforward compensation based on the self-characterized model.     

Dynamic trajectory planning study of planar two-dof redundantly actuated cable-suspended parallel robots

This paper analyzes a set of dynamic trajectories for planar two-dof redundantly actuated cable-suspended parallel mechanisms. In recent literature, the global dynamic trajectory planning problem of cable-suspended mechanisms was addressed and some of the characteristic properties of such robots were revealed. In this paper, actuation redundancy is introduced and the dynamic trajectory planning is addressed using a series of periodic trajectories (i.e. straight line and circular periodic trajectories) and the application of the antipodal theorem. The experimental results obtained show that introducing actuation redundancy increases the dynamic capabilities of the robots. Also, cable tensions acquired via tension sensors confirm that cables always remain taut during all experimental verifications at feasible frequencies and that they are consistent with the tension variations predicted by theory. Furthermore, special frequencies are specified that are similar to those encountered with non-redundant mechanisms. Additionally, an alternative architecture is proposed to deal with cable interferences and it is shown that the novel architecture leads to improved dynamic capabilities when compared to the original architecture.     

Singularity analysis of three-legged, six-DOF platform manipulators with URS legs

A special class of platform manipulators is the subject of this paper. These manipulators comprise two platforms connected by three legs, each being composed of one universal (U), one revolute (R) and one spherical (S) joints, which gives the manipulator six degrees of freedom. Hence, two actuators are required per leg. Under the assumption that the two R joints proximal to the fixed platform, and making up the U-joint, are actuated, we derive the differential kinematic relations between actuator joint rates and mobile-platform twist. This model comprises two Jacobian matrices, the forward- and inverse-kinematics Jacobians. These relations are then applied to the singularity analysis of the parallel manipulator developed at Singapore Institute of Manufacturing Technology and Nanyang Technological University.     

DBR微腔激光器典型参数的开关调制响应及控制

以微腔激光器的典型代表垂直腔面发射半导体激光器(VCSEL)为例，选择自发辐射因子为控制参数，数值模拟了大信号深度调制情形下VCSEL的非线性动力学特性，实现了类似于边缘发射激光器的分岔，周期加倍分岔，多稳和混沌状态的稳定控制，得到分岔点位置和周期轨道与控制参数的变化关系，以及相应地调制参量和自发辐射因子的取值范围，计算结果较好地拟合了文献实验结果。     

Development and hybrid force/position control of a compliant rescue manipulator

Performing search and rescue tasks in the ruins after disasters demand rescue robots with slender and compliant structure to accommodate the complicated configurations under debris. This paper presents the structural design and system composition of a novel tendon-sheath actuated compliant rescue manipulator with slender and flexible body. The proposed robot can drill into the narrow space where rescuers and traditional rigid robots cannot get in because of size limitation or toxic environment. The self-sensing calibration, dynamic modeling, and hybrid force/position control trajectory of the compliant gripper with integrated position and force monitoring capabilities are analyzed and discussed. With the aim of regulating the gripper displacement and clamping force during operation, a hybrid force/position control strategy is proposed based on a cascaded proportional-integral-derivative (PID) controller and a fuzzy sliding mode controller (FSMC). Experimental setups mainly consisting of servo motor, tendon sheath transmission components, compliant gripper, and real-time control system are established to calibrate the strain gauge sensors and identify the dynamic model parameters. Further experimental investigations involving force tracking experiments, position tracking experiments, and object grasping experiments are carried out. The experimental results demonstrate the effectiveness of the developed self-sensing approach and control strategies during rescue operation.     

硅片加工损伤机理的压痕、划痕研究

系统地分析了硅片的压痕、划痕的损伤机理,指出单晶硅压痕、划痕的损伤形式主要有微裂纹、位错、面缺陷、非晶及多晶相变等,材料的塑性去除和单晶硅的金属相变(Si-Ⅱ相)有关。该研究对分析单晶硅片机械加工过程中材料的损伤机理有重要的指导意义。     

Solder Volume Effects on the Microstructure Evolution and Shear Fracture Behavior of Ball Grid Array Structure Sn-3.0Ag-0.5Cu Solder Interconnects

The standoff height of ball grid array (BGA) structure solder joints has a significant influence on the formation and growth of interfacial intermetallic compounds (IMC). The results show that the thickness of the IMC layer at the solder/Cu interface of BGA structure Cu/Sn-3.0Ag-0.5Cu/Cu joints increases with decreasing standoff height after reflowing. The growth behavior of the total IMC layer is controlled by a diffusion process with the growth rate increasing with standoff height. Both the standoff height and isothermal aging time greatly influence the shear behavior of joints, the shear strength of which shows a parabolic trend with increasing standoff height, while the nominal shear strain decreases monotonically with increasing standoff height. The fracture location of BGA structure joints changed from the middle of the solder matrix to near the interface when the standoff height was increased. After undergoing isothermal aging at 125°C, the fracture mechanism of solder joints changed from ductile fracture to the mixed mode of brittle and ductile fracture with increasing standoff height.