Table of Content

25 April 2014, Volume 25 Issue 8

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Singularity Robustness Algorithm for Robot Inverse Kinematics

Yang Zhen, Yang Wenyu, Zhang Xiaoping

2014, 25(8):  995-1000. 

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In order to solve the singularity problem of Jacobian matrix in the inverse kinematics numerical solutions, an algorithm for singular handling was proposed. Based on the damped least-square method, by Jacobi singular value decomposition, the second condition number k2 was made up as a new singular index, which compensated the deficiency of condition number k representing the singularity. Experiments verified the practicability and accuracy of k2. A new self-adaptive adjustment of the damped coefficient was proposed related to k2 and strengthened the singularity robustness of inverse kinematics algorithm. Experimental and simulation results were presented to verify the validity of the proposed algorithm. The contrast results show that the algorithm is stable near singular points, and that the continuity and stableness of the joints motion are guaranteed.

Fatigue Life Analysis of Gears Based on Ride Simulation Test

Zhang Jiancheng, Zhang Qingxia, Mao Zhiyong

2014, 25(8):  1001-1006. 

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Based on virtual prototype dynamic model, wheel box gears' load spectrum of different work sections was obtained through ride simulation test. Through three-dimensional contact stress analysis, stress-time-course of gear's dangerous section was acquired, interpolation method was applied to modify the simulation load under constant torque. The distribution regularity of random load was analyzed and two dimensional joint probability density function under multiple working conditions was synthesized with weight coefficient method. Thus full-life kilometer fatigue design load spectrum of wheel box gears was established. Two dimensional probability Miner rule was adopted to calculate fatigue life of the parts. Some relevant parameters which influenced gear life were analyzed, a new method of fatigue life analysis on wheel box gears was provided.

An Approach to Estimate Tool-chip Average Friction Coefficient Based on FEM Simulation Results and Turning Experiments

Bi Huangsheng, Xiong Liangshan, Huang Ruofeng, Mao Kuanmin

2014, 25(8):  1006-1009,1016. 

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The friction coefficient between chip and tool rake face has a significant impact on residual stress distribution on workpiece surface in FEM simulations, but general FEM softwares do not provide a method for determining the friction coefficient. As for this problem, a method for estimating the average tool-chip friction coefficient was proposed herein by using AdvantEdge FEM simulations, turning experimental results and the residual stress distribution. The residual stress distribution simulated by the friction coefficient which was calculated with the method mentioned above is closer to experimental residual stress distribution, compared with the AdvantEdge FEM default friction coefficient.

Adaptive Fuzzy Control of Nonholonomic Mobile Robots with Bounded Inputs

Ye Jinhua, Li Di, Ye Feng

2014, 25(8):  1010-1016. 

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A saturated adaptive fuzzy dynamics control approach for trajectory tracking of uncertain nonholonomic mobile robots with bounded torque inputs was proposed herein. By using this approach, the kinematics controller and dynamics controller were designed independently based on backstepping technology. The problem of control value jumps was solved by using the shunting control technology in the kinematics controller. And the dynamics controller contained a saturated controller and an adaptive fuzzy approximator, where the saturation function and the limited control parameters were employed to ensure the bounded torque inputs. The impact of unknown uncertainties on system which were hard to be solved by conventional means were eliminated effectively by the fuzzy logic system combined with the adaptive method. The convergence and asymptotic stability were proven by Lyapunov direct method, the high control performance and strong robustness of the proposed controller were verified by simulation results.

Impact of Stator's Inclination Angle on Pressure Signals of Positive Pulse Generator

Zhao Changqing, Liu Kai, Zhao Tong, Jia Sang, Ma Ying

2014, 25(8):  1017-1020. 

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To increase the signal strength of PP-MWD, considerable optimization of the inclination angle and defection characteristics were needed. Numerical simulation models for different inclination angles were developed by means of computational fluid dynamics techniques. Analysis was made to study the impacts of changing the inclination angles of stators on the amplitude and velocity of pressure signals of rotary valves. The reasonability of theoretical analysis was validated by experiments. The results show that the stator's flowing area influences on the pressure signal of logging tools by a large extent. As the inclination angles of stator decrease, the pressure signal amplitude gets smaller. The inclination at the both sides gets stronger pressure signals than unilateral inclination. Research results are instructive and meaningful to the design of rotary valves of PP-MWD.

Research on High-precision Positioning System of an Underwater Platform

Zeng Zhilin, Xu Guohua, Xu Bing, Zhao Chuncheng

2014, 25(8):  1021-1027. 

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A high precision underwater hydraulic position servo system with coarse and fine tune work mode was designed for quick diving and high precision leveling of an underwater experimental platform. The basic composition and principles of the hydraulic system were analyzed, and the positioning model was established. An adaptive backstepping control method was used to overcome the parametric uncertainty and nonlinear characteristics of the hydraulic system. In order to avoid the over-running load conditions of the hydraulic system during the diving and leveling processes, the “lowest point fixed” scheme called  “chase” was chosen. The simulation and experimental results indicate the robustness of designed controller, and the hydraulic system can realize high precision position servo control.

Design and Implementation of High Speed Motorized Spindle's Non-contact Electromagnetic Loading System

Qiu Ronghua, Liu Hongzhao

2014, 25(8):  1027-1032. 

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As the problems of high speed motorized spindle's contact loading, a non-contact loading equipment with electromagnet was designed. The equipment was mainly composed by loading disc with high permeability, direct current(DC) electromagnet, constant current source testing part. The electromagnetic force was produced on loading disc during interaction between the iron-nickel alloy loading disc with diameter of 80mm, thick of 40mm and DC air-gap magnetic field. The spindle load of cutting forces was simulated by the electromagnetic forces. And so non-contact loading on high speed motorized spindle could be realized. Using the presented equipment, loading experiments were done to the grinding motorized spindle with type of 170MD18Y16. And the results show that the value of loading and setting are accordant. The presented equipment can meet the requirements for the loading on high speed motorized spindle. The rotate speed of spindle and exciting current are main factors influencing non-contact electromagnetic loading during the air-gap unchanged.
 

Study on Piston Cushion Structure of High-speed Hydraulic Cylinder

Zhao Wei, Huang Yuzhao, Yu Zheqing, Ruan Jian

2014, 25(8):  1033-1036. 

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The theoretical analysis and experimental research for the cushion process of a high-speed hydraulic cylinder with a piston cushion structure was introduced. The whole cushion process was divided into two stages, the orifice throttle cushion and the tapered gap throttle cushion. A mathematical model of the cushion process was established, based upon the mathematical model, the influence of the structural parameters on the cushion velocity and the pressure of cushion chamber was analyzed. The experiment for the cushion process of two sets of prototypes with different structural parameters was done. The theoretical and experimental results are consistent with each other basically.

Research on New Multi-sectional Interval Codes Applied to Grating Measurements

Liu Xiangyang, Guo Tao

2014, 25(8):  1037-1041. 

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The encoding method of a linear encoder used in precision position measurement was described. Based on studying the traditional interval coding method, a new multi-sectional interval code was proposed as a new interval coding method for linear encoder. This encoding method allowed that any two consecutive distance among the three adjacent reference marks were unique. The absolute position was confirmed by judging two adjacent interval distance. The new multi-sectional interval codes were compared with the traditional interval codes using the software MATLAB. It is concluded that the new multi-sectional interval codes have obvious advantages.

Distributed Memory Mechanism in Parallel Multiprocessor Motion Control System

Cheng Xin, Wu Huachun, Hu Yefa, Zhou Yunfei

2014, 25(8):  1041-1046. 

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Towards the parallel multiprocessor computing architecture in high speed and high precision motion control system, this paper proposed a design of distributed memory mechanism, where every parallel node based on digital signal processing(DSP) was designed with its local memory. Message passing service based on user-defined internal bus was designed to realize automatic replication of shared data in different local memories, which meant that globally shared memory was set up based on physical distributed memory to optimize the data-exchange performance among each parallel computing nodes. The validity of this hardware-implemented memory mechanism was proved in actual applications.

Fault Diagnosis of Rolling Bearings Based on Morphological Component Analysis and Envelope Spectrum

Chen Xiangmin, Yu Dejie, Li Rong

2014, 25(8):  1047-1053. 

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When a rolling bearing was locally damaged, its vibration signals were often composed of harmonic components with system characteristics of the rolling bearing, impulse components with fault information and random noise. A new method for the fault diagnosis of rolling bearings was proposed based on the MCA and envelope spectrum. The harmonic components, impulse components and random noise components were separated from the vibration signals of a fault rolling bearing by using the improved MCA, the impulse components were then analyzed by using the Hilbert envelope demodulation analysis, and the fault diagnosis of rolling bearing was carried out according to the envelope spectrum. Simulation and application examples show that the proposed method is effective in extracting the fault characteristics from the vibration signals of local damaged rolling bearings.

Visualization Simulation in Air Separation Based on Particle System and Texture Mapping

Jin Binying, Xu Jinghua

2014, 25(8):  1053-1058. 

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The process of air separation system is complex, this causes the real fluid flow among the machines is difficult to simulate and express. For visualization of the key process of air separation system of adsorption, heating and distillation, a visualization simulation method for air separation equipment was proposed based on particle system and texture mapping. A key frame coordinate of recursive transformation was used to describe the position and motion of the particle flow source, custom particle flow source was adopted to simulate heating and mass transfer properties, and multi-scale texture mapping was applied to describe the flow trace of the machines. An interactive visualization platform for the development of integrated planar was developed. The key performance simulation and visualization of complex air separation equipment was complemented finally．

Navigation and Localization Strategy of Seeing Eyes Robot Using LF and UHF RFID Tags

Chen Chao, Jin Zuguang, Tang Jian

2014, 25(8):  1059-1064. 

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This paper presented a navigation and localization method combined LF and UHF of RFID tags for a seeing eyes robot. According to the relationship between the energy level of signal strength of RFID and distance, UHF tags were set at the target point in order to estimate the coordinate and the macro-straight path of the robot. LF tags were defined and set  at the inflection point with the purpose of correcting the interference errors caused by the UHF location, as well as reducing redundant or wrong actions produced by obstacle avoidance sensors which were commonly occurred at the point. Experimental results show that the proposed method can improve positioning accuracy and reduce redundant and repeat path for the seeing eyes robot in indoor environment. 

Manufacturing Information Model for Growth Design

Yang Jinyong

2014, 25(8):  1065-1070. 

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Aiming at the demands to control the decomposing granularity of function surface in the process of the growth design, function mode was used to express the product geometric structure information based on its geometric property, which was also used as the carrier to integrate product manufacturing process information. So the manufacturing information model was built based on function surface. The theory of information entropy was introduced to quantify the model information. The minimum value of conceptual product manufacturing information entropy was used as the control target of function surfaces decomposing granularity to determine whether to stop the growth of conceptual product or not. The correctness of the theory was verified through the specific product design experiments.

Study on Resonance Characteristics of Hydraulic Excited Flutter Device

Xing Tong, Li Xiuwu, Ma Hongjie, Jin Defeng, Du Xuewen

2014, 25(8):  1071-1074. 

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The vibration model of a single-acting hydraulic excited flutter device was established herein, and the resonance frequency was deduced. The modal analysis during the exciting vibration was done by ANSYS soft. Experimental studies find some interesting phenomenon during resonance, where amplitude increases significantly, waveform is better than that of non-resonance process. In addition, resonance frequency fells slightly and bandwidth of resonance is larger because of the fluid-structure interaction.

An Ant Colony Optimization Algorithm for Multi-objective Disassembly Line Balancing Problem

Zhu Xingtao, Zhang Zeqiang, Zhu Xunmeng, Hu Junyi

2014, 25(8):  1075-1079. 

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Combining the characteristics of disassembly line, a mathematical model was established for multi-objective DLBP where several optimization objectives were considered, such as minimizing the number of workstations, balancing idle time at each workstation, removing hazardous, high demand components as early as possible and minimizing the disassembly direction changes,then, an improved ant colony optimization algorithm was developed. In this algorithm, a hybrid search mechanism by comprehensively considering utilization, exploration and random search was constructed. The remove time, the harm and the demand of parts of DLBP were collaboratively considered and used for the heuristic information of the proposed algorithm. Finally, the computer experiments on different scale test instances were performed and the results indicate the feasibility and validity of the proposed algorithm.

Research on Motion Planning of Linear Motor Driven Piston Pump

Dong Wutao, Nie Songlin

2014, 25(8):  1080-1084. 

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To improve the flow rate properties of piston pump, the feasible motion planning of a linear motor driven piston pump was investigated systematically, which was easier to achieve constant flow rate. Through computation, it is finded that the solution of four double-acting motor driven piston pump in motion planning of triangular waves with phase difference of π/2 or incontinuous trapezoidal waves with phase difference of π/2 is the possible one with redundancy. The system model of four double-acting linear motor driven piston pump was established by the software of AMESim, using the feasible solution to achieve the constant flow of piston pump theoretically. Through simulation, the solution of triangular waves with phase difference of π/2 is the preferred motion planning, which has less actual flow pulsation.

A Novel Method of Constraint Expression and Handling for Complex Component Structural Intelligent Optimization

Hua Haiyan, Lin Shuwen, Shen Zhenhui

2014, 25(8):  1085-1091,1101. 

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To improve the efficiency of handling the constraints for complex mechanical components as well as to extract and utilize the deep implicit constraint knowledge, a novel method of constraint expression and handling for complex mechanical component structural optimization was proposed based on the dual evolution theory of cultural algorithm. A hierarchical constraint expression model was established and the hierarchical constraint intelligent handling mechanism was constructed with the guidance of task knowledge. Furthermore,the process for handling the deep implicit constraint knowledge in optimal process was proposed to realize the evolution of implicit constraint knowledge so as to guide the evolution of population space. Finally, structural optimization of an excavator boom was taken as an example to demonstrate the feasibility and effectiveness of this method.

Reliability Growth Evaluation Model of Binomial System Based on DGM(1,1)

Liu Jiefang, Liu Sifeng, Fang Zhigeng

2014, 25(8):  1092-1095. 

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For a binomial system that had several stages' informations, this paper introduced an Bayesian evaluation methods of reliability growth. The model first determined whether the system reliability grew according to the Laplace inspection. Then prior information could be obtained according to the reliability point estimation of each stage using DGM (1,1) model. And the similarity coefficient of prior information and field information were calculated. Finally, prior information and the field information were fused using the Bayesian method. The examples show the effectiveness of the proposed model.

Research on Simulation Method in Construction Vehicle Design Based on an Iterative Question-answer Driven Process

She Yini, Ning Xiaobin, Lin Qiong

2014, 25(8):  1096-1100. 

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In order to support a question-answer driven simulation process, a design process model was introduced, that was capable to describe problem statements, model specifications, simulation models and problem answers as separate objects. This enabled a granularity level of information that allowed traceability on an object-to-object level between the attributes in the requirement specifications and the estimated product properties. A methodology for an iterative question driven simulation process using this design process model was illustrated in a modeling and simulation scenario of an attachment in a large hydraulic excavators. The simulation model produced a number of 5120 different hinge point design programs according to Monte Carlo methods. Based on the principle of the large working range, the best working performance under lifting, digging and horizontal pushing operating conditions, the best hinge point design was chosen. The results demonstrate that it is a practical valid method for process modeling of complex products, and it can meet the design requirements and has excellent performance design program for the hydraulic excavator attachment.

Aero-engine Rotor-stator Rubbing Positions Identification Based on Casing Acceleration Signals

Yu Mingyue, Chen Guo, Jiang Guangyi, Li Chenggang, Feng Guoquan, Wang Deyou

2014, 25(8):  1102-1108. 

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A method of aero-engine rubbing positions identification based on casing acceleration signals was proposed. The rotor experimental rig of aero-engine was used to simulate rubbing faults of different radial rubbing positions. The normalized energy features of wavelet partial maximum modulus were used to input into support vector machine by comparison with directly extracted casing accelerate signal mean square features. The results show that the normalized energy features based on the wavelet partial maximum modulus are more effective than direct extracted casing acceleration signal mean square feature in rotor-stator rubbing positions identification.

Pulsed Eddy Current Testing Based on Gradient Magnetic Field Measurement

Qi Yong, Liu Xiangbiao, Li Yong, Chen Zhenmao, Li Weixin

2014, 25(8):  1108-1112,1135. 

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This paper proposed a new PECT technique by introducing GMFM which was intensively used in magnetic resonance imaging(MRI) and superconducting quantum interference devices(SQUID) to PECT in an effort to enhance the PECT sensitivity to surface cracks. The scanning results regarding PECT evaluation of surface cracks were intensively analyzed via simulations and experiments. It is found that the GMFM signals have higher sensitivity than that of the conventional PECT differential signals in evaluation of surface cracks, which verifies the validity of the proposed method.

Research on Dynamic Characteristics of Ultrasonic Squeeze Film and Its Influence Factors

Ma Xizhi, Hu Wei, Wang Ting

2014, 25(8):  1113-1117. 

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The present paper established the models of dynamic characteristics of squeeze gas film by means of compressible gas hydrodynamic lubricating theory, and  these models were solved by nonlinear value methods. In order to understand the regularities of dynamic characteristics of the squeeze film, some values of dynamic characteristics of squeeze film at some specific cases were provided. The influences of the stead film thickness, excitation amplitude and frequency on the coefficients of dynamic characteristics were discussed. It is found that these influences are very significant. At last, an experiment for measuring static stiffness coefficient of squeeze film was carried out. The results were compared with the theoretical values, it is shown that they are consistent in magnitude. The conclusion of this paper can be as the foundation of ultrasonic squeeze bearing design.

Analysis on Phase Transformation Stress after Pulse Current Discharging of  Metal Component with Buried Crack

Fu Yuming, Wang Junli, Zheng Lijuan

2014, 25(8):  1117-1121. 

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The circular buried crack of 40CrNiMo steel was arrested and strengthened by pulse discharging experiments. Comparative analysis with the changes in the macroscopic morphology, chemical composition and microhardness near the crack tip before and after the discharge was performed. Experimental results show that the microstructure and micro-hardness of transformation zone are improved greatly. The theoretical formula of phase transformation stress around crack tip is deduced using transient heat conduction equations, phase transformation kinetics and Eshelby equivalent inclusion. The compressive stress is generated in phase transformation zone, proving that electromagnetic heating effect plays a part in inhibiting crack propagation.

Arc-brazing of Aluminum Alloy to Brass

Dong Honggang, Zhang Xuchao, Yang Jicheng, Hu Wenjin

2014, 25(8):  1122-1125. 

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Aluminum alloy and brass sheets were lap joined by tungsten insert gas(TIG) arc welding using Zn-15%Al solid-cored filler wire. The mechanical properties of the joint,microstructure in the weld and distribution of major alloying elements in the intermetallic layer were examined. The test results display that the tensile strength of the as-welded joints reaches 164MPa, and that of post-weld heat treated joints is as 160MPa. The analysis results reveal that the dendrites further grow up during post-weld heat treatment, and some dendrites detach from the interface into the weld and worsen the joint performance. The intermetallic layer in the joints mainly consists of CuZn5 phases and grows into weld in the form of columnar crystals.

Research and Test on Pneumatics ABS Key Techniques

Huang Zhi, Liu Jian, Hu Kai, Liu Lipan

2014, 25(8):  1126-1130. 

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A practical adaptive algorithm for reference body velocity estimation was proposed to improve the performance of ABS controller based on logic threshold algorithm. Body deceleration was corrected by utilizing the information deduced from peak value of recovered wheel velocity at every control cycle. A controller based on logic threshold algorithm and ABS ECU was developed. The controller was tested on HIL simulation platform based on xPC Target system, and then road tests were carried out to validate the developed algorithms and calibrate control parameters. Experimental results show that ABS controller estimates the body deceleration quickly and correctly, the proposed reference body velocity algorithm is suitable for a variety of typical braking conditions, and slip rate is restrained to reasonable range by the logic threshold controller.

Study on Braking Rate of Disc Brake Unit RZS

Xia Demao, Xi Ying, Li Tao, Chen Zhe, Ye Qian

2014, 25(8):  1131-1135. 

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Firstly, the working principle of RZS disc brake unit was introduced including the service brake, parking brake and manual auxiliary release. Then, the DOF of RZS disc brake unit was studied and analyzed. According to the different initial conditions of the pad clearance, all the movement joint points of the unit were determined before and after the braking action. Static analysis of each component was performed and the relationship between the compressed air force acted on the piston and braking force was also deduced. At last, the braking rate and its change rules were also calculated and discussed before and after the pad clearance was adjusted respectively. It is found that: although a little change in the pad clearance, it will bring a large fluctuation in total braking force.