基于DSP的主动光学力促动器控制系统设计

针对步进电机型力促动器,设计了一种基于DSP的力促动器控制系统,并进行了测试.系统以TMS320F28069型DSP作为主控制器,采用ADS1259高精度A/D转换器采集传感器LoadCell输出力信号,通过DSP片上PWM模块输出电机控制脉冲给电机细分驱动芯片TMC389,驱动步进电机转动,形成力控制闭环.系统软件采用PID控制算法来校正力促动器输出偏差,并给出了控制程序流程图.实验测试结果表明:该控制系统具有良好的响应特性和较强的抗干扰能力,满足主动光学实验系统的要求.     

空间望远镜主镜的主动支撑面形校正分析

大型空间望远镜的主镜由于受重力、温度和装配等因素的影响,会产生面形误差,影响光学系统的成像效果。为了提高空间望远镜主镜对重力、温度的适应性,采用400mm弯月镜进行了主动支撑面形校正研究。主动支撑方案由3个固定支撑和7个主动支撑构成,利用Zernike系数和最小二乘法计算力促动器的校正力大小。使用有限元仿真软件分析了镜子在重力工况和稳态温度工况下,校正前后的面形结果。分析结果显示,采用本文的主动支撑方案,各工况下被校正后的主镜面形精度达到均方根(RMS)值<λ/20的设计指标,面形质量有明显的提高。同时,在重力工况中引入了实际装调中可能存在的安装误差等因素,仿真结果显示装配误差对校正结果影响较小,说明主动支撑系统具有较高稳定性。     

小口径离轴抛物面反射镜挠性支撑设计分析

关于反射镜支撑稳定性优化设计问题,离轴抛物面反射镜作为空间光学遥感器的重要光学元件,面形精度直接影响遥感器性能。针对反射镜所处环境,组件一阶频率要求高,设计了一种反射镜背部中心单点挠性支撑结构,并利用拓扑优化技术对反射镜进行了轻量化设计。为了结构设计的合理性,采用有限元技术对反射镜组件进行了模态分析、结构强度分析、谐响应分析及热环境分析。分析结果表明:反射镜在重力作用下最大面形误差RMS=1.16nm;在±10℃温度载荷作用下最大面形误差RMS=11.46nm;反射镜组件一阶频率为574.19Hz。使挠性支撑结构具有良好的静、动态特性和热尺寸稳定性,满足反射镜面形要求。     

基于Labview的主动光学力促动器PID控制系统

为了在400mm口径主动光学实验系统中,实现对12个力促动器输出压力值的精确控制,在Labview环境下,利用PID控制箱,配合PCI-6284采集卡等相应硬件开发了力促器闭环控制系统。实验结果表明,通过闭环,各促动器的精度达到了±0．05N,满足实验要求。该系统运行稳定,控制精度高,可应用于大型望远镜的主动支撑。     

空间光学微位移促动器的定位测控研究

为解决大口径空间光学镜面在轨组装技术的高精度定位需求,设计了一种微位移促动器,并对单促动器和多促动器六自由度平台分别进行了定位测控研究。通过建立单促动器的运动学方程、多促动器六自由度平台的运动学方程,解决了微位移促动器的高精度定位问题。搭建了实验硬件系统,编写了软件控制程序,对单促动器分别进行了小步长测试和大步长测试,并对多促动器六自由度平台进行了定位测试。实验结果表明,设计的微位移促动器与多促动器六自由度平台的定位精度满足设计指标。     

振动对反射镜胶连接的影响分析与试验

在空间相机反射镜连接优化的研究中,胶连接是空间相机反射镜连接常用的连接方式之一。在相机振动试验、发射等力学环境作用下胶接连接状态、胶接力可能会发生变化。胶连接状态的变化使反射镜镜面面形发生变化,导致相机成像质量变差。目前尚无直接测量反射镜胶接力在振动力学试验前后变化的方法,直接采用完成镜面加工的反射镜进行振动试验,势必增加了反射镜研制风险。为了研究振动对反射镜胶连接的影响,采用设计胶接试验件的验证方法,将检测胶连接状态的变化转换为光学测量镜面面形的变化,解决了直接测量的胶连接变化难的问题。振动试验前通过有限元的方法仿真分析了力胶接试验件的动力学特性,为力学试验条件制定提供了参考。通过对比振动试验前后胶接试验件面形RMS值,胶接试验件面形最大变化为1.26nm,在设计和光学测量误差变化允许范围内,表明改进的反射镜胶连接方法有一定可行性,为验证振动对胶连接的影响提供一种新方法。     

基于图像识别的二次反射镜面形质量检测方法

针对二次反射技术中二次反射镜空间尺度较大、表面反射率高的特点,利用周期性分布的彩色编码板和图像识别方法获得彩色色块虚像的分布情况,通过与理想色块虚像分布的对比计算实际矢量与理想矢量的偏差角,再根据反射定律计算反射法线偏差角分布用于评估待测二次反射镜面形质量。通过仿真实验与样品试验进行验证,结果表明该方法能够实现高精度的、高效的二次反射镜面形质量检测,为二次反射聚光效率评估提供有效的数据支持,保证光热发电站的发电效率。     

目标跟踪系统自校正解耦融合Wiener平滑器

针对带未知模型参数和噪声的多传感器目标跟踪系统,为了解决信号的平滑问题,分别利用系统辨识及相关方法得到未知模型参数和噪声方差的局部估值,并对这些局部估值求平均值作为它们的融合估值。然后将具有高可靠性的在线融合估值代入到基于现代时间序列的最优解耦融合Wiener平滑器中即可得自校正解耦融合,使自校正融合Wiener平滑器收敛于相应的最优融合Wiener平滑器,并具有渐近最优性。从而证明自校正平滑器能够很好地解决未知模型参数和噪声统计系统的平滑问题。最后利用Matlab软件仿真验证了该自校正解耦融合Wiener平滑器算法的有效性。     

使用最小二乘迭代相移方法测量透明元件

为了更精确地测量透明平板前后两个面的面形相位发布,提出了一种基于最小二乘迭代的相移算法。通过一次最小二乘相移算法后,可以得到相应的透明平板面形图,但是由于初始得到的相位值存在误差,因此得到的面形图精度并不会很高。因此需要通过得到的面形图推导出准确的相位值,本算法通过最小二乘发多次迭代的方法,计算出较准确的初始相移值。对该方法进行仿真实验后,可知此算法的测量精度较高且抗噪能力比较好,仿真得到面形图的PV值与RMS值误差值均小于0.006λ。在实际测量结果中,得到测量结果的PV值误差小于0.09λ,RMS误差小于0.02λ。测量到的面形与物体真实面形接近,测量精度较高。     

连续子空间预测控制方法及其应用

针对工业过程中常见的连续时间系统,提出一种新型的连续子空间预测控制方法。首先,利用拉格朗日滤波器对连续时间系统模型进行转换,得到子空间预测输出;然后,对构造的输入输出和拉格朗日矩阵进行QR分解得到子空间预估器,将子空间预估器用于构造增量型未来预测输出值,进而设计出连续子空间预测控制器;最后,通过工业蒸发器系统过程控制仿真实验,验证了所提出控制方法的有效性。     

Computation of static shapes and voltages for micromachineddeformable mirrors with nonlinear electrostatic actuators

In modeling micromachined deformable mirrors with electrostatic actuators whose gap spacings are of the same order of magnitude as those of the surface deformations, it is necessary to use nonlinear models for the actuators. In this paper, we consider micromachined deformable mirrors modeled by a membrane or plate equation with nonlinear electrostatic actuator characteristics. Numerical methods for computing the mirror deformation due to given actuator voltages and the actuator voltages required for producing the desired deformations at the actuator locations are presented. The application of the proposed methods to circular deformable mirrors whose surfaces are modeled by elastic membranes is discussed in detail. Numerical results are obtained for a typical circular micromachined mirror with electrostatic actuators     

Miniature Pneumatic Curling Rubber Actuator Generating Bidirectional Motion with One Air-Supply Tube

Soft actuators driven by pneumatic pressure are promising actuators for mechanical systems in medical, biological, agriculture, welfare fields and so on, because they can ensure high safety for fragile objects from their low mechanical impedance. In this study, a new rubber pneumatic actuator made from silicone rubber was developed. Composed of one chamber and one air-supply tube, it can generate curling motion in two directions by using positive and negative pneumatic pressure. The rubber actuator, for generating bidirectional motion, was designed to achieve an efficient shape by nonlinear finite element method analysis, and was fabricated by a molding and rubber bonding process using excimer light. The fabricated actuator was able to generate curling motion in two directions successfully. The displacement and force characteristics of the actuator were measured by using a motion capture system and a load cell. As an example application of the actuator, a robotic soft hand with three actuators was constructed and its effectiveness was confirmed by experiments.     

Modeling of pneumatic muscle with shape memory alloy and braided sleeve

Pneumatic muscle (PM) of flexible actuators used in bionic robot is an active area of recent research. A novel PM with shape memory alloy (SMA) braided sleeve is proposed in this paper, and SMA is used to improve PM working characteristics. Based on the principle of virtual work, output force model of PM and relationship with braided wire inner-stress are established, and analysis of PM deformation has shown that braided wire length is the key factor of output force characteristic. Based on the crystal structure transitions, the relationship of temperature with wire shrinkage is derived. Then, the synthetic dynamics of novel PM is established. A physical prototype of PM with SMA braided sleeve is developed, and test platform that is built for the experiment. Experiment and simulation test of static isometric-length, static isobaric-pressure, and dynamic characteristics are done. The experimental results are compared with the simulation of theoretical model. Moreover, based on experiment, model of output force was improved by adding a correction factor to deal with the elastic force of rubber tube. The results analysis demonstrates that the established models are correct, and SMA wires can reinforce PM and make PM working characteristics adjustable. PM proposed in this paper has greater output force and is beneficial to achieve more accurate control that is useful for manipulating fragile things.     

Development of copper based miniature electrostatic actuator using WEDM with low actuation voltage

Fabricating electrostatic micro actuator, such as comb-drive actuator, is one of the demanding areas of the MEMS technology because of the promising applications in modern engineering, such as, micro-switches, attenuators, filters, micro-lenses, optical waveguide couplers, modulation, interferometer, dynamic focus mirror, and chopper. For the fabrication, most of the cases silicon monocrystalline wafers are used through complex process. To etch the silicon substrates, researchers often use deep reactive-ion etching or anisotropic wet etching procedure which are time consuming and unsuitable for batch fabrication process. Again, resent research shows that comb-drive actuators need comparatively high voltage for actuation. In solving these problems, the study presents a copper based electrostatic micro actuator with low actuation voltage. Using wire electrical discharge machine (WEDM), the actuator is fabricated where a light weight flexible spring model is introduced. Capacitor design model is applied to present a voltage controlling electronic circuit using Arduino micro controller unit. The experimental result shows that the actuator is able to produce 1.38 mN force for 15 V DC. The experiment also proves that coper based actuator design using WEDM technology is much easier for batch processing and could provide the advantages in rapid prototyping.     

Thin-Film Piezoelectric Unimorph Actuator-Based Deformable Mirror With a Transferred Silicon Membrane

This paper describes a proof-of-concept deformable mirror (DM) technology, with a continuous single-crystal silicon membrane reflecting surface, based on$ PbZr _0.52 Ti_0.48 O _3$(PZT) unimorph membrane microactuators. A potential application for a terrestrial planet finder adaptive er is also discussed. The DM comprises a continuous, large-aperture, silicon membrane “transferred” onto a 20$,times,$20 piezoelectric unimorph actuator array. The actuator array was prepared on an electroded silicon substrate using chemical-solution-deposited 2-$mu m$-thick PZT films working in a$d _31$mode. The substrate was subsequently bulk-micromachined to create membrane structures with residual silicon acting as the passive layer in the actuator structure. A mathematical model simulated the membrane microactuator performance and aided in the optimization of membrane thicknesses and electrode geometries. Excellent agreement was obtained between the model and the experimental results. The resulting piezoelectric unimorph actuators with patterned PZT films produced large strokes at low voltages. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/silicon thickness and design showed a deflection of 5.7$~mu m$at 20 V. A DM structure with a 20-$mu m$-thick silicon membrane mirror (50 mm$times,$50 mm area) supported by 400 PZT unimorph actuators was successfully fabricated and optically characterized. The measured maximum mirror deflection at 30 V was approximately 1$~mu m$. An assembled DM showed an operating frequency bandwidth of 30 kHz and an influence function of approximately 30%. 1738     

激光拾音头力矩器数学模型的研究

通过力矩器的结构分析，采用自动控制理论推导出一个动态数学模型。在此基础上。运用Matlab提出一种力矩器的非线性回复力模型实验仿真拟合的方法并对某种力矩器进行了实验仿真。这种方法可以方便和有效地使用于大部分光学头，但是由于非线性的存在。对大的动态范围仿真拟合的精度较差。     

A new method for actuating parallel manipulators

This paper presents a new technique of actuating a parallel platform manipulator using shape memory alloy (SMA). This is a type of smart materials that can attain a high strength-to-weight ratio, which makes them ideal for miniature application. The work is mainly to develop a new SMA actuator and then incorporating the actuator in building the parallel manipulator prototype. The SMA used in this study is a commercial NiTi wire. The SMA wire provides an actuating force that produces a large bending and end displacement. A 3-UPU (universal–prismatic–universal) parallel manipulator using linear SMA actuators was developed. The manipulator consists of a fixed platform, a moving platform and three SMA actuators. The manipulator workspace was specified based on the restrictions due to actuator strokes and joint angle limits. System identification techniques were used to model both heating and cooling processes. An ON/OFF control was performed and the results showed closeness in simulation and experimental results. This study showed that shape memory alloy actuated beam can successfully be used to provide linear displacement. The built prototype indicates the feasibility of using SMA actuators in parallel manipulators.     

A hybrid surface tension seal for pneumatic and hydraulic microactuators

Recent research revealed that microactuators driven by pressurized fluids are able to generate high power and force densities at microscale. One of the main technological barriers in the development of these actuators is the fabrication low friction seals. This paper presents a novel scalable seal technology, which resists the actuation pressure relying on a combination of a clearance seal and a surface tension seal. This approach allows to seal pressures of more than 800 kPa without leakage. The seal is tested on an actuator with a bore of 0.8 mm2 and a length of 13 mm, which was able to generate forces up to 0.32 N.