Sep 2006, Volume 1 Issue 3

  • Select all
  • ZOU Hui-jun, ZHANG Long, ZHANG Qing
    Since 1982, the symposiums on mechanism in China has been held fifteen times. In the past 24 years, Chinese mechanism has experienced a phenomenal development. Generally, fundamental research on traditional mechanisms is enhanced; mechanism and creative design of products are closely combined; modern mechanism with advanced and new technology is opened up; and mechanism is promoted to modernization. These are manifested in the following aspects: theory research on analysis and synthesis of traditional mechanism is deeply developed; computer-aided design on mechanisms is realized vigorously; conceptual design of mechanism system and mechanical products is energetically pushed; research on robot mechanisms and its industrial application is deeply developed; research on analysis and synthesis of controllable mechanisms and compliant mechanisms are energetically carried out; research on the dynamics of mechanisms and machines is vigorously developed; and reformation of teaching contents and system of mechanism is energetically carried out. Through the above-mentioned aspects of theory research and practical application, the theoretical and academic levels of Chinese mechanism can be considered at the advanced international level. However, there are not many original and breakthrough research achievements of fundamental research in China. In the meantime, there is a larger gap in the aspect of practical application of mechanism in the country compared with advanced countries in the world.
  • YAN Han, WANG Xian-kui, DUAN Guang-hong
    The model of a precision linear motor drive device (PLMDD) and its control requirements are analyzed. In order to enhance the tracking and anti-disturbance performance of the system, its third-order model is established, and disturbance-observer based input revising feedforward error compensation robust control algorithm, combined with integral-separated proportional integral derivative (PID) control algorithm is proposed. This includes feedback control algorithm and feedforward control algorithm. The feedback controller improves system tracking performance and suppresses load and mechanical disturbance while the feedforward controller compensates phase hysteresis introduced by feedback control. Theoretical analyses, simulations and experiments show that this control method increases the tracking precision of PLMDD from ±5 μm to ±2 μm and dramatically improves its anti-disturbance ability.
  • SHANG De-guang, SUN Guo-qin, DENG Jing, YAN Chu-liang
    On the basis of the continuum fatigue damage theory, a nonlinear uniaxial fatigue cumulative damage model is first proposed. In order to describe multiaxial fatigue damage characteristics, a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach. The proposed model can consider the multiaxial fatigue limit, mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters. The recurrence formula of fatigue damage model was derived under multilevel loading, which is used to predict multiaxial fatigue life. The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner s rule.
  • CHEN Hao-sheng, CHEN Da-rong, WANG Jia-dao, LI Yong-jian
    To analyze the effects of non-Newtonian lubricants and surface roughness in journal bearing lubrication, a modified Reynolds equation is derived. In the equation, differential viscosity and the first normal stress function are defined to specify the rheological properties of non- Newtonian medium. Flow factors are used to specify the effect of surface roughness. The modified Reynolds equation is numerically calculated using super over relaxation method. Numerical results of the lubrication show that the differential viscosity is the principal non-Newtonian property affecting the lubrication, it is determined by the material parameters of the lubricant and is affected by the shearing rate. Under its effect, the load capacity of non-Newtonian lubricants is not always higher or lower than that of Newtonian lubricants . The effect of the first normal stress difference increases under the conditions of dynamic loading. Surface roughness shows an obvious effect on load capacity when it is greater than one-tenth of the film thickness, and the surface with longitudinal pattern affects the load capacity most. However, surface roughness has less effect on lubrication results than lubricants  non-Newtonian property.
  • HU You-min, YANG Shu-zi, DU Run-sheng
    As manufacturing becomes increasingly decentralized, flexible and reconfigurable, more research needs to be done on monitoring and diagnosis technology that accommodate these new trends. The distributed condition monitoring and diagnosis technology based on the flexible and reconfigurable  concept is studied here. A condition monitoring diagnosis model based on the distributed flexible and reconfigurable idea is proposed in this paper. The component makeup and functions of this model are discussed in detail. The model can fulfill in most instances the manufacturing system requirements for changing the configuration of the monitoring diagnosis system according to different manufacturing system configurations. This model also realizes the flexibility and reconfigurability of the monitoring diagnosis system in some degree. The model has already spawned a successful prototype for monitoring a chemical plant in accomplishing monitoring and control of the production process and equipment. Finally, some future research work is pointed out.
  • CHENG Jian, FAN Xiu-min, XU An, HONG Xin, HUANG Wei-dong
    This paper describes a manned maneuvering unit (MMU) virtual reality system. Based on the dynamics/kinematics model of an astronaut equipped with an MMU, a disturbance model of the astronaut s arms under zero gravity conditions is developed. After measuring three initial-position information, the astronaut s arms tracking information is inputted by some tracker setting on an operator using real-time emendation and correction. Finally, the paper presents two different results between loading and unloading the disturbance model within the progress of simulation. From the different results, we find that the motion of an astronaut s arms has greater influence over space walking with the same control mode. The MMU virtual reality provides a new method for the simulation of real space walking, and also a perfect method for developing prototype MMU.
  • YANG Jin-tang, KONG Jian-yi, XIONG He-gen, JIANG Guo-zhang, LI Gong-fa
    Based on the mechanical features of the controlled driving component and the characteristics of controlled mechanism of two degrees of freedom, a circle fitting optimization model of controlled mechanism that accurately realizes the multi-point track, has been established. The generalized inverse method for solving compensation movement displacement has been presented.
  • LI Wei-hua, SHI Tie-lin, YANG Shu-zi
    To deal with pattern classification of complicated mechanical faults, an approach to multi-faults classification based on generalized discriminant analysis is presented. Compared with linear discriminant analysis (LDA), generalized discriminant analysis (GDA), one of nonlinear discriminant analysis methods, is more suitable for classifying the linear non-separable problem. The connection and difference between KPCA (Kernel Principal Component Analysis) and GDA is discussed. KPCA is good at detection of machine abnormality while GDA performs well in multi-faults classification based on the collection of historical faults symptoms. When the proposed method is applied to air compressor condition classification and gear fault classification, an excellent performance in complicated multi-faults classification is presented.
  • CHAO Dai-hong, LIU Rong, WU Yue-min, SHI Long, ZONG Guang-hua
    In the fields of micro/nanopositioning application, error analysis is an effective way to enhance the precision of micromanipulators. Manufacturing imperfections, which are inevitable, are the most important factors influencing the accuracy. Therefore, various manufacturing imperfections were studied by taking a planar 3 degrees of freedom (3-DOF) flexure hinge based microrobot as a case. By formulating static stiffness of the robot, mapping between manufacturing imperfections and end-effector positioning accuracy was obtained. Using the theoretical calculation and finite element method (FEM), effects of various machining imperfection types on end-effector positioning accuracy were evaluated. The results showed that errors of the radium of the hinges and angular differences of the centerline of the hinges were dominant factors resulting in output errors. Conclusions drawn from the experiments can be used to instruct the design of compliant parallel mechanisms by distributing various manufacturing differences of configurable parameters to guarantee precision in the positioning of the end-effector within the required range; they may also be helpful while calibrating this kind of manipulator.
  • LU Chun-guang, MENG Li-li
    It is extremely important for procedure of process design and management of process data for product life cycle in Computer Aided Process Planning (CAPP) system, but there are many shortcomings with traditional CAPP system in these respects. To solve these questions, application of workflow technology in CAPP system based on web-integrated Bill of Material (BOM) tree is discussed, and a concept of integrated BOM tree was brought forward. Taking integrated BOM as the thread, CAPP systematic technological process is analyzed. The function, system architecture, and implementation mechanism of CAPP system based on Browser/Server and Customer/Server model are expatiated. Based on it, the key technologies of workflow management device were analyzed. Eventually, the implementation mechanism of integrated BOM tree was analyzed from viewpoints of material information encoding, organization node design of integrated BOM tree, transformation from Engineering BOM (EBOM) to Process BOM(PBOM), and the programming implementation technology.
  • JIANG Kai, CHEN Hai-xia, YUAN Sen-miao
    It is a very important task to automatically fix the number of die in the image recognition system of a fully automatic die bonder. A multiobjective image recognition algorithm based on clustering Genetic Algorithm (GA), is proposed in this paper. In the evolutionary process of GA, a clustering method is provided that utilizes information from the template and the fitness landscape of the current population. The whole population is grouped into different niches by the clustering method. Experimental results demonstrated that the number of target images could be determined by the algorithm automatically, and multiple targets could be recognized at a time. As a result, time consumed by one image recognition is shortened, the performance of the image recognition system is improved, and the atomization of the system is fulfilled.
  • WANG Xuan-ze, YANG Lian-gen, ZHONG Yu-ning
    The equivalent circuit of inductance sensor is analyzed. Amplitude-displacement and phase-displacement equations are deduced for non-ideal carrier wave and inductance parameters. Simulation computation shows the corresponding digital curves. Considering that the traditional process method is an approximate one, a new method is presented to simultaneously obtain the amplitude and phase of output signal of sensor by simultaneity A/D and ellipse fit arithmetic. According to the characteristic of the amplitude-displacement and phase-displacement curves, we obtain displacement by phase and amplitude respectively when the sensor is close to the zero point position and away from other positions on the basis of the experiment. The experiment showed that this method can improve precision of measurement, and it can also work for the whole linear range of sensors even if the magnification is very high.
  • LIU Ya-xiong, ZONG Xue-wen, TANG Yi-ping, LU Bing-heng
    The traditional slicing method of reverse engineering has been used in product measure from time immemorial. This method however has the disadvantage of low contrast of the cross-sectional pictures of an object. In order to overcome the said shortcoming, a new slicing method of reverse engineering, based on the principle of refraction and reflection of a prism, has been propounded. According to the reflectivity of the object, one of the illuminating methods  straight illuminating or inclined illuminating  is adopted. These methods can enable one to obtain the image of the cross-section of a bright object with a dark background or the opposite. Experiments have proved to show the advantages of this new slicing method for high contrast of the cross-sectional pictures. To eliminate geometrical distortions caused by the refraction and reflection of the prism, a mathematical transformation model can be set up to correct the image by using relevant software. Eventually, a RP model of a temporomandibular joint fabricated according to its slicing pictures is illustrated.
  • FEI Yue-nong, Wu Qing-hua
    This paper presents a robot manipulator tracking controller based on output feedback linearization. A sliding mode perturbation observer (SPO) is designed to estimate unmeasurable states and system perturbations that involve system nonlinearities, disturbances and unmodelled dynamics. The use of SPO allows to input/output linearize and decouple the strongly coupled nonlinear robot manipulator system merely by the feedback of joint angles. The controller design does not need an accurate model of the robot manipulator. Simulation studies are undertaken based on a two-link robot manipulator to evaluate the proposed approach. The simulation results show that the proposed controller has more superior tracking control performance, with payload changing in a wide range, in comparison with a sliding mode controller (SMC) designed based on state feedback linearization with full states available.
  • FU Yi-li, JIN Bao, LI Han, WANG Shu-guo
    A fuzzy robot motion planning approach is proposed in unknown environments for three-degree industrial robots. The proposed planning system is composed of several separate fuzzy units, which control individually each manipulator joint. Each unit combines a repelling influence, which is related to the nearby obstacle, with the attracting influence produced by the final manipulator configuration, to generate actuating command for each link. Effectiveness of the proposed approach is verified through simulation.
  • JIAO Jing-pin, HE Cun-fu, WU Bin, FEI Ren-yuan, WANG Xiu-yan
    For wave propagation in dispersive media, the arrival time of the acoustic emission signal to the sensor is dependent on the setting of the threshold voltage, which results in the inaccuracy of the acoustic emission location. Based on the wavelet transform and the theory of modal acoustic emission, a new method is proposed to improve the accuracy of acoustic emission source location. It is believed that the acoustic emission signal propagation in the structure has the characteristics of multi-mode and dispersion, and the acoustic emission source location should use the arrival time to sensors obtained from the output signals not only at the same mode but also at the same frequency. The wavelet transform is used to resolve the problem. By utilizing the time-frequency data of the wavelet, the frequency-dependent arrival time traveling is easily obtained; by numerical computation of the wave s propagation in structure, the group velocity of the guided mode is also obtained, therefore the accuracy source location is realized. The acoustic emission source location experiments were conducted in a thin steel plate and results show that the technique is an effective tool for acoustic emission source location.
  • QIU Bai-jing, QIAN Guo-hong, XIANG Zhong-ping, LI Zuo-peng
    Due to complicated barriers, it is difficult to track the path of the mowing robot and to avoid barriers. In order to solve the problem, a method based on distance-measuring sensors and fuzzy control inputs was proposed. Its track
  • YUAN Feng, WANG Tai-yong, NIE Hui-juan
    Function and principle innovation is the ultimate innovation of a product. To achieve Function and principle innovation design of mechanical products, a new process model of function and principle solving is proposed, based on TRI
  • GUO Wei-dong, GUO Xin, ZHANG Yu-ru
    Reverse driving character plays an important role in evaluating the performance of a haptic device, and it is the primary rule in the mechanical design. This article mainly investigates the problem of 2-DOF haptic device design f
  • FU Zhuang, ZHAO Yan-zheng, LIU Ren-qiang, DONG Zhi
    A space solar cell bonding robot system which consists of a three-axis Cartesian coordinate s robot, coating device, bonding device, orientation plate, and control subsystem was studied. A method, which can control the thickness o
  • CHEN Xiao-xia, YONG Jun-hai, CHEN Yu-jian
    How to obtain intersection of curves and surfaces is a fundamental problem in many areas such as computer graphics, CAD/CAM, computer animation, and robotics. Especially, how to deal with singular cases, such as tangency or superposi
  • WANG Xin-jie, BAI Shao-xian, HUANG Ping
    A new mathematical model for thin film lubrication is established by taking into account the effect of an electric double layer. In the present paper, experiments are carried out on a self-made tester. With a composite block and a