Table of Content

    10 November 2023, Volume 34 Issue 21
    Yaw Rate Calculation and Vehicle Stability Control Considering Tire Nonlinearity
    MIN Delei, TONG Ruting, WEI Yintao
    2023, 34(21):  2521-2530.  DOI: 10.3969/j.issn.1004-132X.2023.21.001
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    Based on the nonlinear tire model, an accurate yaw rate calculation method was proposed to calculate the accurate yaw rate and applied to vehicle stability control. Tire nonlinearity was characterized by the brush model. The equivalent stability factor was obtained by perturbation analysis, and the accurate analytical solution of the yaw rate was obtained. The analysis of the existence of analytical solutions indicates that tire nonlinearity may impact vehicle stability. Real vehicle tests and control simulations based on vehicle models show that considering tire nonlinearity may effectively improve the calculation accuracy of the steady-state yaw rate as the target parameter, and improve the effect of vehicle stability control. 
    Adjustment of Thickness Uniformity for Precision Electroformed Mold Insert
    YANG Zhonghao, JIANG Bingyan, MA Zhigao, YANG Di, ZHANG Lu,
    2023, 34(21):  2531-2539.  DOI: 10.3969/j.issn.1004-132X.2023.21.002
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    In electroforming processes, the nonuniform distribution of electric field at cathode edge led to a higher deposition rate at the edge, which resulted in the nonuniform thickness of electroformed mold insert. A cathode fixture with side grooves on top of the shielding baffle was designed herein. The research results show that the nonuniformity is as 4.3% with the thickness of electrodeposited layer is as 0.1 mm, which is the 16.5% of the nonuniformity without shielding plate. The precision injection mold insert with a thickness of 1.1 mm and thickness nonuniformity less than 8% was successfully fabricated based on the cathode side groove and shielding baffle. 
    Design and Analysis of a Novel Weak-coupling Parallel Hip Exoskeleton with Large Angle of Rotation
    XU Jilong, LIU Fucai, NIU Yunzhan
    2023, 34(21):  2540-2547.  DOI: 10.3969/j.issn.1004-132X.2023.21.003
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    A novel bio-syncretic hip exoskeleton with large-angle and weak-coupling characteristics was proposed to solve the problems such as small workspace, difficult forward kinematics modeling, and complex control of parallel hip exoskeletons. The detailed structures of two-stage prismatic joint were designed, and the expression for calculating the slope of the groove was obtained. The man-machine complexs forward and inverse position solutions were derived by closing-vector-circle method. The inverse Jacobian matrix was obtained by taking the derivative of the inverse position solution equation. Performance analysis shows that the man-machine complex has the advantages such as large range motion, no internal singularities, good force transfer performance, and easy control.
    Research Advances in Chatter of Metal Cutting Systems Involving Time Delays
    REN Yongsheng, YAO Donghui, ZHANG Jinfeng
    2023, 34(21):  2548-2567,2576.  DOI: 10.3969/j.issn.1004-132X.2023.21.004
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    Metal cutting processes typically had distinct characteristics of delayed system.  Chatter phenomenon was a highly complex phenomenon which widely occured in various metal cutting processes.  Chatter prediction in cutting processes was the premise of chatter suppression.  The theoretical method for chatter prediction, in-process recognition techniques for chatter prediction, and influencing factors for metal cutting dynamics were reviewed.  Applications of machine tool structure materials were introduced.  Some problems and research directions in future were proposed. 
    Performance of Functional Gradient Explosion-proof Structures of Experimental Cabin under Explosive Loading
    CHEN Qinghua, LYU Ke, WANG Dejun, WANG Jiangang, WANG Jianye, FENG Peng
    2023, 34(21):  2568-2576.  DOI: 10.3969/j.issn.1004-132X.2023.21.005
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     In order to improve the explosion impact resistance of explosion-proof doors in large environmental experimental cabins, a new type of dual functional gradient core layer was designed based on a variable gradient negative Poissons ratio honeycomb core layer and the introduction of a tensile expansion concave hexagonal honeycomb structure. ABAQUS software was used to comprehensively analyze the impacts of different gradient core layers on the collapse mode and energy absorption characteristics of explosion-proof doors under impact loads, with a focus on exploring the changes in deflection and core layer compression of the front and rear panels under different explosion loads. The research results indicate that by properly configuring the directional gradient and concentric gradient, the specific energy absorption may be improved, and the core layer may achieve a more ideal deformation mode.  After optimization, the deflection of the front panel of the explosion-proof door was reduced by 23% to 26.7%, and the energy absorption capacity was increased by 64.6% to 83.6% compared to a single gradient core layer. 
    Topology Optimization Design of Flexible Parallel Microgrippers with Low Parasitic Displacements
    WANG Qiliang, LIU Tong, LI Yongqi, WEI Jianming, XU Meijuan, HONG Yongfeng
    2023, 34(21):  2577-2584,2591.  DOI: 10.3969/j.issn.1004-132X.2023.21.006
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    Aiming at the problems that piezo-driven flexible microgrippers were easy to rotate and slip during clamping, which were hard to keep stable clamping, a flexible microgripper was designed using continuum structure topology optimization method. The solid isotropic material penalty(SIMP) model topology description method was used herein, and the ratio of maximum output displacement to input displacement, minimum rotation angle, minimum parasitic displacement, and end stiffness were used as optimization objectives. The topology optimization problem was divided into two stages by hierarchical sequence method. The topology optimization design model of the flexible parallel microgrippers was developed and solved by the optimisation criterion(OC) method to obtain a flexible parallel microgripper with low parasitic displacements. The effectiveness of the algorithm was verified by simulation comparisons of the microgrippers without suppressing rotation angle and parasitic displacement. The designed microgrippers were machined and measured. The unit parasitic rotation and relative parasitic displacement is as 0.001 384 27 mrad/μm and 0.7%, respectively, The designed microgrippers have a low parasitic displacement and rotation angle, the microgrippers may realize parallel gripping, which verifies the validity of the design.
    Identification of Position-independent Geometric Errors for Rotary Axes of Five-axis Table-tilting Machine Tools
    LIANG Xiaobing, LU Yaoan, WANG Chengyong,
    2023, 34(21):  2585-2591.  DOI: 10.3969/j.issn.1004-132X.2023.21.007
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     PIGEs of rotary axes were the important factors that affected the machining accuracy of five-axis machine tools. Taking AC type five-axis table-tilting machine tools as an example, an identification method of PIGEs of rotary axes was proposed based on the differential evolution algorithm. Firstly, a mathematical model of PIGEs and length change of ball bar was established. The initial PIGEs may be identified by existing methods. Then, an optimization objective function was defined, and the PIGEs of the rotary axes were optimized as a whole by a differential evolution algorithm to improve the identification accuracy of the rotary axes PIGEs. The experimental and simulation results show that the proposed method may effectively improve the identification accuracy of the PIGEs of the rotary axes. 
    Hemodynamics Analysis of Interventional Robots in Diagnosis and Treatment Based on Fluid-structure Interaction
    ZHU Zongming, JI Suqiang, WANG Hao, TANG Puhua, LIANG Liang
    2023, 34(21):  2592-2599.  DOI: 10.3969/j.issn.1004-132X.2023.21.008
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    The blood flow characteristics of interventional robots in motion at different heights in blood vessel were studied, with a bi-directional FSI method considering blood flow and blood vessel deformation, and the fluid flow field measurement system for microrobots. The results show that in pulsatile blood flow, height of the interventional robots in blood vessel has a little impact on hemodynamics parameters such as blood flow streamline, blood pressure, and vessel wall shear stress, but they are much greater than those as no interventional robot in blood vessel. The hemodynamics parameters calculated by elastic vessel model are slightly smaller than those calculated by rigid vessel model. When the robot intervenes, the maximum blood flow velocity is as 0.48 m/s, and the maximum blood pressure is as 119.3 Pa. The distribution of the numerical results are similar to the experimental ones. 
    Compound Rules and Reinforcement Learning Based Scheduling Method for Mixed Model Assembly Lines
    GUO Jutao, LYU Youlong, DAI Zheng, ZHANG Jie, GUO Yu
    2023, 34(21):  2600-2606,2614.  DOI: 10.3969/j.issn.1004-132X.2023.21.009
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     A scheduling method was proposed based on compound rules and reinforcement learning for balancing and sequencing problems of mixed model assembly lines. A balancing rule set and a sequencing rule set were designed with the consideration of mathematical model, and a proximal policy optimization(PPO) algorithm featured with Actor-Critic training procedure and preferential experience learning mechanism was employed to regulate weighted parameters of these rules, in order to generate reasonable balancing and sequencing solutions. In comparative experiments, the proposed scheduling method demonstrates the effectiveness over other methods including PPO algorithm with single rule, compound rules, and a genetic algorithm.
    An Adaptive Robust Unscented Kalman Filter Localization Algorithm Based on Dynamic Residual
    XU Wan, CHENG Zhao, XIA Ruidong, CHEN Hancheng
    2023, 34(21):  2607-2614.  DOI: 10.3969/j.issn.1004-132X.2023.21.010
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     Aiming at the problems that the standard unscented Kalman filter(UKF) localization algorithm could not meet the high-precision localization requirements of mobile robots when moved on uneven ground, an ARUKF localization algorithm was proposed based on robust estimation theory. The ARUKF adaptively adjusted the predicted value of UKF according to the dynamic residual, reduced the influences of external interference on the predicted values of the systems, improved the accuracy and robustness of the system, speeded up the operation by reducing the computational complexity of the sampling processes, and improved the real-time performance of the system. The simulation and field test results show that the ARUKF algorithm may converge faster for the disturbance generated by uneven ground, and have better accuracy, robustness, and real-time performance, compared with the UKF algorithm and the improved UKF algorithm based on Sage-Husa. The average distance error is less than 2 mm, and the average angle error is less than 0.016 rad, which may meet more stringent requirements of the construction site. 
    Optimal Layout Method of 2D Irregular Parts under Complex Cutting Process Constraints
    WU Dianjian, ZHANG Sanqiang, YANG Guangyou,
    2023, 34(21):  2615-2621.  DOI: 10.3969/j.issn.1004-132X.2023.21.011
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     Aiming at the problems of low material utilization and low working efficiency in cutting production line of two-dimensional irregular parts(2DIP), an optimal layout method was proposed for the 2DIP under complex cutting process constraints. A mathematical model of the 2DIP cutting stock problem was established with the optimization goal of maximizing material utilization. The parts were positioned by a graphics collision algorithm which improved material utilization. The layout units were dynamically constructed by the translation, rotation, mirroring and other operations of part graphics to improve the efficiency of continuous cutting and automatic palletizing of parts. Feasibility and effectiveness of the method were verified by the comparative analysis of examples. 
    Machining Performance and Material Removal Mechanism of High-speed Milling of CFRP with Variable Angle under Minimal Quantity Lubrication
    ZHANG Lifeng, ZHANG Xiaoguang
    2023, 34(21):  2622-2628.  DOI: 10.3969/j.issn.1004-132X.2023.21.012
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     High-speed cutting performance of CFRP was investigated by a specially designed regular dodecagonal cutting trajectory method. Factors such as cooling and lubrication conditions, fiber cutting angles, cutting speed, and down/up milling were analyzed for their influence mechanism on the cutting performance of CFRP. Material removal mechanism under typical fiber cutting angles was analyzed. The results indicate that when PCD milling cutter mills unidirectional CFRP with a constant 30° angular difference, both of normal cutting force(Fn)and tangential cutting force(Ft) follows a specific pattern. Compared to down milling, Fn reduces 25% at least and Ft reduces 40% at least in up milling, while the surface roughness Sa reduces 10% to 35%. Compared to dry cutting, nanofluid for minimal quantity lubrication machining Ft reduces 20% approximately, and cutting temperature decreases around 40%.
    Fixed-angle Method for Examines Automatic Fiber Placement Based on Point Cloud Surfaces 
    JIANG Shikuo, WANG Xiaoping, WANG Kai, JIN Jiang
    2023, 34(21):  2629-2636,2645.  DOI: 10.3969/j.issn.1004-132X.2023.21.013
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     The examines automatic fiber placement on point cloud surfaces was researched. The direct projection method with moving least-squares projection technique was proposed to project the initial path. A point cloud slicing method was improved to propose a point cloud projection slicing method. A cubic B-spline interpolation algorithm was used to generate initial paths by fitting projection points, and an equidistant offset algorithm for chord length subdivision projections was proposed. Based on stretching the path splines end, a boundary processing method was proposed to solve the problem that the offsetting paths could not reach the surface boundary. Finally, the algorithm was visualized by reverse engineering module of CATIA, and the systematic relationship between the path planning algorithm and the 3D modelling software was established. 
    Fatigue Life Prediction of Flexible Lattice Structures Prepared by Digital Light Process
    WANG Wei, JI Xiaogang, FANG Chuang, NIU Guofa
    2023, 34(21):  2637-2645.  DOI: 10.3969/j.issn.1004-132X.2023.21.014
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     Based on Brown-Miller model for complex lattice structures, a fatigue life prediction method was proposed to solve the reliability problem of their damping capacity. The fatigue life for lattice structures of 3 cell arrays was predicted by numerical simulation and fatigue tests. The influence of unit cells configuration and relative density on power-law parameters was analyzed indepth, and a prediction model between relative density and fatigue strength was constructed. The results indicate that the S-N curves of lattice structures conform to a power-law relationship. The power-law coefficient is influenced by both unit cell configurations and relative density, while the power-law exponent is dependent on the unit cell configuration and unaffected by relative density.