连续热镀锌生产线的简化与数学建模

为研究气刀处的带钢大幅抖动原因,试对带钢连续热镀锌系统进行动力学建模。整个镀锌生产线是一个复杂的大系统,动力学建模时必须对其进行适当简化,以得到一个仅包含热张紧辊、退火段带钢、沉没辊、出锌锅上行段带钢、塔顶辊、下行段带钢、转向辊和八个弹簧支承的比较简单的混杂系统力学模型。先将简化后的混杂系统分成多个子模型,用带钢张力和附加惯性载荷代替边界条件,然后基于牛顿第二定律对这些子模型进行建模,以期得到整个系统的控制方程。此项研究可为混杂系统建模提供一种新参考。     

A re-configurable cross-sectional imaging system for reverse engineering based on a CNC milling machine

This paper presents a novel reverse engineering digitizing system for full part geometry, which is based on a cross-sectional imaging device built in a NC milling machine. The system successively captures a picture for each planar cross-section contour of the part by end-milling and CCD imaging, and builds the geometry for both external and internal surfaces of the complex 3D part based on a set of the vectored cross-sectional contours. The system mainly consists of three components: a NC milling machine, a cross-sectional imaging device and a computer control unit. Some issues involving the principle and process flow of the system, encasing materials, cross-sectional imaging and NC code generation, etc. are described in detail. Built on an existing NC milling machine, a portable device for capturing the cross-sectional images is designed, which includes an isolated light source, a digital camera, a protective case, a rigid arm and a robust tripod. The device, connected to a computer control unit, serves as a highly flexible accessory for the NC milling machine, constructing the cross-sectional imaging system for reverse engineering. Furthermore, the error analysis and accuracy assessment of the system are also addressed. A typical case is discussed in detail to illustrate the applications of the system. Such a re-configurable digitizing system for reverse engineering offers a number of advantages, such as the functional extension of an existing NC milling machine, low costs, and rapid construction. As a result, this system provides a feasible and useful scheme for many enterprises to construct their own reverse measuring system based on existing equipment to aid in rapid product development and extend the function of existing equipment.     

Fiber optic pressure sensor based on a single-mode fiber F–P cavity

In this paper, we propose and experimentally demonstrate a pressure sensor based on birefringent single-mode fiber F–P cavity using optical heterodyne. The proof of concept device consists of a light source, a polarizer controller, a modulator, a RF generator, a single-mode fiber Fabry–Perot cavity, a strain inspector, an erbium doped fiber amplifier, a filter, a polarizer, an optical spectrum analyzer, and a digital communication analyzer. The dynamic range of the proposed sensor is explored. The results demonstrate the new concept of fiber pressure sensors and the technical feasibility for pressure measurements.     

电控单体泵燃油喷射系统耦合仿真

以某一典型的电控单体泵供油单元、可压缩高压油管以及机械式一级弹簧喷油器组成的燃油喷射系统为原型,建立了电控单体泵燃油喷射系统和喷油正时控制策略的耦合仿真模型,为多学科领域复杂系统建模仿真提供了解决方案和系统工程设计的完整平台.     

Three DOF parallel link mechanism utilizing smooth impact drive mechanism

For a wide range of purposes, a compact and smart positioning stage is in strong demand. Our final goal is to fabricate a positioning mechanism that possesses multi-degrees of freedom, a wide movable area, dexterity, rigidity, and high speed. To meet most of requirements, i.e., except that of a wide movable area, a parallel mechanism is superior to a serial link mechanism. However, a lack of smart actuators has previously resulted in a large and complicated construction of a parallel mechanism.A purpose of this paper is to propose a new parallel link that utilizes a smart actuator called smooth impact drive mechanism (SIDM), and to verify its advantage for a smart and compact positioning stage. The SIDM actuator is an interesting mechanism that achieves a long stroke with fine positioning resolution. This paper treats a three DOF stage containing three SIDM actuators and a two-dimensional positioning sensor. The first operation test was carried out, and it was confirmed that a position control was successful. The average deviation was 18.6 μm and the standard deviation was 9.31 μm. As another trial, a circle 3.0 mm in diameter was successfully drawn. These values were insufficient for the SIDM actuator that has potentially nanometer-level resolution. The rough positioning resolution seems to be due to inferior driving method and mechanical ricketiness of the joints. In the near future, high speed and accurate positioning control could be realized with overcoming these problems.     

套式钻模的应用研究

在各种长度和直径的圆柱体或空心圆柱体的外圆柱面上沿横截面圆周方向钻削,有较高的位置精度要求且呈多层均匀分布或多层非均匀分布或螺旋均匀分布或螺旋非均匀分布的孔和螺纹孔的方法进行了研究,重点介绍了长度与外径比＆gt;5的圆柱体或空心圆柱体。研究发现,目前常见的固定式钻模、回转分度式钻模、移动式钻模、翻转式钻模和盖板式钻模都不是最佳选择,因为它们的钻模板均为长方体,与圆柱面不能完全配合,导致夹紧元件和定位元件的结构复杂,形式单一且制造周期长,成本高,夹紧钻模的方式单一。套式钻模的钻模板为空心圆柱体,空心圆柱体的独特之处是使套式钻模可与圆柱面完美配合,夹紧元件和定位元件的结构简单,形式灵活且制造周期短,成本低,夹紧钻模的方式灵活,从而使其成为在各种长度和直径的圆柱体或空心圆柱体的外圆柱面上钻削各种排列组合方式的孔和螺纹孔的最佳选择。     

A highly integrated FPGA-based nuclear magnetic resonance spectrometer

The digital circuits required for a nuclear magnetic resonance (NMR) spectrometer, including a pulse programmer, a direct digital synthesizer, a digital receiver, and a PC interface, have been built inside a single chip of the field-programmable gate-array (FPGA). By combining the FPGA chip with peripheral analog components, a compact, laptop-sized homebuilt spectrometer has been developed, which is capable of a rf output of up to 400 MHz with amplitude-, phase-, frequency-, and pulse-modulation. The number of rf channels is extendable up to three without further increase in size.     

Robust scene recognition using a GA and real-world raw-image

This paper presents a new concept of scene recognition by a genetic algorithm (GA), using the 2-D gray-scale image of a working space, termed here as raw-image, and a model shaping the 2-D top-surface of a target object. In fact here, the problem of object recognition in the raw-image is changed into an optimization problem of a model-based evaluation function. We make use in this research of a GA, as a search and optimization method. This GA employs a model-based fitness function as its objective function to perform the search of a target in the raw-image. In this research, three object models, namely a frame model, a surface model, and a surface-strips model are investigated in order to determine which one is the best for scene recognition in a noisy environment. Also, in order to appraise the recognition performance of each model, a comparative study is performed by analyzing the answers to the following criteria questions: sensitivity, reliability, and speed. The effectiveness of the method has been verified through experiments using real-world raw-images, and the method has shown its robustness of object recognition with the surface-strips model, in spite of the noises in the scene.     

没有针轮的摆线变速机

在摆线针轮减速机中,针轮是由针齿壳、针齿销、套3种精密零件组成;在摆线曲面的线形探索中,找到了摆线的法线运动规律,设计出摆线的法向导杆机构,用普通圆柱铣刀和砂轮沿法向导杆进给和切削,准确地创成加工各种摆线及其等距曲线.从而可以制造出纯滚动啮合的外齿和内齿摆线轮,使得由十几以致上百个零件组成的针轮只需一个内齿摆线轮取代,进而制造没有针轮的摆线减速机,使减速机的效率显著提高,单级的最大减速比由现在的87提高到200以上.     

Actuation of a robotic fish caudal fin for low reaction torque

In this paper, a novel caudal fin for actuating a robotic fish is presented. The proposed caudal fin waves in a vertical direction with a specific spatial shape, which is determined by a so-called shape factor. For a specific shape factor, a traveling wave with a vertical phase difference is formed on a caudal fin during fin motion. It will be shown by the analysis that the maximum reaction torque at the joint of a caudal fin varies depending on the shape factors. Compared with a conventional plate type caudal fin, the proposed fin with a shape factor of 2π can eliminate the reaction torque perfectly, while keeping the propulsion force unchanged. The benefits of the proposed fin will be demonstrated by experiments.