Table of Content

25 August 2021, Volume 32 Issue 16

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Research Progresses of Basic Equipment Manufacturing and High-grade Integrated CNC Machine Tools

HU Lai, ZHA Jun, ZHU Yongsheng, WEI Wenming, LI Dongya, LUO Ming, NIU Wentie, CHEN Yaolong

2021, 32(16):  1891-1903.  DOI: 10.3969/j.issn.1004-132X.2021.16.001

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In order to solve the key problems faced by the aerospace manufacturing fields and improve the service capability for the industries，the machine tool industry proposed to build an innovative capability platform for high-grade CNC machine tools in the field of aerospace manufacturing. The research progresses in four aspects of basic assembly manufacturing and high-grade CNC machine tools were summarized about the innovation platform, including: motorized spindle unit technology(dynamic analysis of high-speed spindle—tool handle—tool system, digital simulation and prototype modal verification analysis); machine tool design(rigid-flexible coupling—electromechanical coupling dynamics of linear axis feed system, verification and analysis of electromechanical coupling dynamic model of multi-axis linkage and high-speed five-coordinate hybrid machining equipment and swing/rotary feed system, innovative structural design of MTC1000 boring, milling and grinding composite machining center); machine tool control(verification and analysis of high-speed start-stop residual vibration suppression technology) and machine tool verification(analysis of field data acquisition, mapping and storage technology for high-speed machining of aerospace structural parts). Finally, the future research trends were prospected.

2DOF Internal Model Control for Steer-by-wire Systems with Time Delay

DU Wenlong, CHEN Li, LIU Wentong, CHEN Jun,

2021, 32(16):  1904-1911，1920.  DOI: 10.3969/j.issn.1004-132X.2021.16.002

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Aiming at the response time delay problems caused by signal transmission, mechanical clearance and friction of the SBW systems, a 2DOF IMC was designed to improve the angle tracking accuracy. The time delay model and the SBW model were established and combined as the nominal model. In order to avoid non-minimum phase terms, an all-pole approximation method was adopted to linearize the time delay model, so the tracking controller and the anti-interference controller might be solved. Compared with the 2DOF IMC without using a nominal model with time delay and the classical PID control, MATLAB/Simulink simulation results show the influences of time delay on the tracking performance of the three methods. The effects of time delay on the tracking performance of the 2DOF IMC using the all-pole, Taylor and Padé approximation methods were compared respectively. Finally, the bench test results of the SBW systems show that the 2DOF IMC based on the all-pole approximation has higher tracking accuracy and better adaptability to time delay.

Collaborative Design Optimization of Damping Layers and Stiffener Layout of Thin-walled Stiffened Plate Structures for Dynamics Performances

NIU Bin, YAN Jiaming, MAO Yuming, LIU Haiyang

2021, 32(16):  1912-1920.  DOI: 10.3969/j.issn.1004-132X.2021.16.003

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In order to reduce the vibrations of thin-walled stiffened plate structures in dynamic environment, a topology optimization method was proposed for designing the layout of reinforced ribs and damping layers. The penalization model of damping material and the ground structure approach were combined in the optimization. The density of stiffened rib and element density of the damping material were introduced as the independent design variables. Two constraints on the material used in the stiffened ribs and the damping layers were considered. The collaborative design optimization of damping layers and stiffening ribs was established with dynamic compliance as the objective function. The optimized topological design of stiffeners and damping materials was realized simultaneously. Several numerical examples of stiffened plate with different damping properties and various excitation frequencies were given to verify the effectiveness of the proposed method.

Kinematic Parameter Optimization of Workspace-based Generalized Spherical Parallel Robots for Ankle Joint Rehabilitation

LIU Xiuying, ZHANG Jianjun, LIU Chenglei, NIU Jianye, QI Kaicheng, GUO Shijie

2021, 32(16):  1921-1929.  DOI: 10.3969/j.issn.1004-132X.2021.16.004

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In order to solve the difficult problems for the existing ankle joint rehabilitation robots to completely fit the motion of the human ankle joints, a high-matching ankle joint motion series fitting model was developed based on bionics, and a new type of three degree of freedom generalized spherical parallel robot was proposed. In order to study the fitting ability of the parallel robots, the degree of freedom characteristics was analyzed based on the spiral theory. The kinematics model of the mechanisms was established, it was clarified that had partial decoupling characteristics based on inverse kinematics. According to the characteristics of the dual spherical centers of the robots, the moving sphere center and the working space of the moving platform were solved. Finally, taking the degree of matching between the working space of the ankle joint motion fitting model and the working space of the robots as the objective function, the genetic algorithm was used to optimize the kinematic parameters. The working space scatter plots of the robots and the model were compared and the effective working space ratios were obtained as 0.79 and 0.86 respectively. The results show that the optimized working space of the generalized spherical parallel robots may meet the motion requirements of the ankle joints. 

Design and Implementation of a Tilt-deformable Quadrotor

LIU Yanwei, PAN Hao, LIU Sanwa, LI Shujuan, LI Yan

2021, 32(16):  1930-1936.  DOI: 10.3969/j.issn.1004-132X.2021.16.005

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To meet the needs of narrow space flight in disaster rescue and military reconnaissance, a quadrotor with independent pitch attitude control was proposed. A tilting degree of freedom was added on the ordinary quadrotor, and using only one servo motor, the quadrotor's pitch attitude could be controlled independently, so that it might hover and fly within a specified pitch attitude. The aerodynamics simulation model of the quadrotor was established, and the influences of airflow interference among rotors on aerodynamics characteristics in tilting states was simulated and analyzed. A test platform for aerodynamics characteristics was built, and the effectiveness of the aerodynamics simulation model was verified by the tests. Finally, a prototype of the quadrotor was developed, and the tilting hover and tilting flight experiments were carried out. The experimental results demonstrate that the quadrotoris able to hover with a pitching angle nearly 90°, and it may achieve stable flight with a pitching angle of 60°, which verify the feasibility of the tilt-deformable quadrotor to fly through the narrow spaces.

Hierarchical Structure Topology Optimization Based on Substructure Method

FU Junjian, SUN Pengfei, DU Yixian, TIAN Qihua, GAO Liang

2021, 32(16):  1937-1944，1951.  DOI: 10.3969/j.issn.1004-132X.2021.16.006

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To avoid the separation of scales in the hierarchical structures topology optimization, and to maintain the connection between different cellular structures, a hierarchical structure topology optimization method was proposed based on the substructure method.  The topology optimization of cellular structures was divided into two hierarchies with the parametric level set method. The topology configuration of the cellular structure was optimized in meso-hierarchy. The spatial distribution of the cellular structure was optimized in macro-hierarchy. The relationship between macro-structure and meso-structure was established using the substructure method. The meso-structures was condensed into a super element, which was then used as the basic element of macro-structures for the structural analysis and optimization. Numerical examples show that the proposed method is effective for the 2D and 3D hierarchical structure topology optimization. The proposed method may effectively guarantee the connection between different cellular structures when considering multiple types of cellular structures in the hierarchical structure design.

Crack Nucleation Position and Propagation Direction of Single Abrasive Grain Scribing Gallium Oxide Crystal Surfaces

ZHOU Hai, ZHANG Jiequn, XU Yameng, SHEN Junzhou, HUANG Mengdie

2021, 32(16):  1945-1951.  DOI: 10.3969/j.issn.1004-132X.2021.16.007

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In order to analyze the crack nucleation position and propagation direction of the new-generation optoelectronic material gallium oxide crystal during ultra-precision grinding and lapping processes, a model of elastic stress field of gallium oxide(010) crystal plane was established by single abrasive grain, and the critical cutting depth of the brittle-plastic transition of gallium oxide(010) crystal plane was analyzed. The nucleation position and propagation direction of radial cracks on the surfaces were predicted during the scribing processes of gallium oxide crystals by MATLAB analysis. The analysis results show that when the cutting depth is less than the critical cutting depth, the radial crack nucleation position is behind the abrasive grain, and the angle between the crack propagation direction and the cutting direction is about 33°. When the cutting depth exceeds the critical cutting depth, the radial crack nucleation position further moves behind the abrasive grain, and the angle between the crack generation direction and the scoring direction is about 51°. In order to verify the theoretical analysis results, a nano-scoring test on gallium oxide crystals was performed. Comparative analysis show that the analytical results of the gallium oxide stress field are highly consistent with the experimental data. Under linear loading conditions, the radial crack deflection angle of the Cube diamond indenter on the gallium oxide crystal(010) crystal plane is between 33.37°and 51.45°.

Study on Patent Harmful Performance Knowledge Mining Based on Semantic Association

LIN Wenguang, LAI Rongshen, XIAO Renbin

2021, 32(16):  1952-1962.  DOI: 10.3969/j.issn.1004-132X.2021.16.008

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In order to provide abundant source of information and depth information for product innovation design, a method for mining patent harmful performance knowledge was proposed based on semantic association. First, harmful performances of the products were defined and classified, and the distribution and semantic characteristics of harmful performances in patents were analyzed accordingly. Second, combined with industrial patent full-text information, word2vec was employed to construct a text vector space model, then the sematic distances of words were calculated by cosine algorithm for merging synonyms. Third, part-of-speech and dependency syntax were introduced to obtain harmful performance keywords from technological background of the patents, and four classification rules were proposed to make association relationship among structural objects and harmful performances, then a database of product harmful performances was built. Finally, focusing on keywords of design scheme components, the related harmful performances were retrieved, and the occurrence probability of different harmful performances of the components was calculated using frequency formula. The domestic shower product patent was selected as an application case and compared with the other three algorithms to verify the feasibility and effectiveness of the proposed method.

Research and Implementation of Trajectory Planning Algorithm for Attacking Robots on Wind Tunnel

SUN Xiaojun, SONG Daiping, LIN Jingzhou, HAN Weihang

2021, 32(16):  1963-1971.  DOI: 10.3969/j.issn.1004-132X.2021.16.009

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 In order to increase the speeds of the robot arms tracking the target trajectory, the target trajectory of the robots was re-planned. By introducing path parameters, constraints such as joint velocity and force/moment were transformed into constraints on trajectory parameters in the trajectory planning algorithm. The maximum velocity curves of path parameters under joint velocity and force/moment constraints were obtained respectively. The maximum velocity curves with multiple constraints were obtained by calculating the intersection of the above maximum velocity curves. In order to improve the computational efficiency of the algorithm, the fuzzy inference method was used to discretize the target trajectory to reduce the optimization scales, and the maximum velocity curves of the joint force/torque constraint were replaced by the velocity curves of the zero value acceleration curves multiplied by the proportional coefficient. The planned trajectory was modified through the speed feature point algorithm and the modification-target algorithm to ensure that the modified target trajectory meets the constraints of joint speed and force/torque, and the velocity curve is smooth. The trajectory planning experimental results shows that the trajectory planning algorithm have better planning performance for target trajectories of different complexity, and may obtain continuous and smooth time approximate optimal trajectories.

Path Planning of Substation Inspection Robot under Road Network and Measurement Constraints

LU Hao, CHEN Yang, WU Huaiyu, CHENG Lei,

2021, 32(16):  1972-1982.  DOI: 10.3969/j.issn.1004-132X.2021.16.010

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The intelligence level of daily inspection tasks might be greatly improved by using robots to measure the temperature of high-voltage lines in substations, but the problems of road network limitation and energy consumed by frequent start-stops were encountered in robot inspection processes. And the mutual restriction between the optimal path and the specific temperature measurement location might be considered. In order to solve the above problems, the substation environment was modeled based on graph theory, and a path planning model with the goal of minimizing time consumption was established by analyzing the pose constraints of the camera when the robot measured the temperature of the target in the road network. Then, a path optimization method was proposed based on the improved ant colony algorithm and the method of selecting inspection stops was also presented based on greedy clustering. And the optimal inspection paths of the robots, the positions of the stops and the sets of temperature measurement points corresponding to each stops were iteratively obtained through ant colony algorithm. Finally, simulation cases were used to verify the feasibility and robustness of the algorithm, and the experimental results of the inspection robots show that the method may be used for substation inspection.

Intelligent Connected Vehicle PnP Networking Model and Decision Fusion Algorithm

ZHOU Xiaochun, LIANG Jun, CHEN Long, WANG Yafei, GONG Jinfeng

2021, 32(16):  1983-1993.  DOI: 10.3969/j.issn.1004-132X.2021.16.011

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To simplify the networking processes of ICVs before multi-sensor fusion, a networking model of self-search—self-identification—self-calibration(S-SIC) was proposed for a PnP environmental sensing sensor. The PnP sensors were searched and connected to ADAS domain by using the depth-first search planning algorithm. The PnP sensors were identified and initialized by using the broadcast messages. The PnP sensors were calibrated by the coordinate transformation matrix of the vehicle body coordinate system and compensation algorithm. Aiming at the incompatibility of ICV multi-sensor data-level and feature-level fusion, a K-m.AW decision-level fusion algorithm was proposed. The experimental results show that the S-SIC model search success rate reaches 92%, and the average search time is as 1.79 s. In the trajectory estimation of the preceding vehicle, the multi-scene fusion estimation based on K-m.AW algorithm is increased by 7.6% and 11.8% respectively compared with contrast algorithms.

Research on Safety Performance of Lane Keeping Assist Systems Based on Human-machine Cooperative Control

SUI Xin, LIU Chunyang, ZHAN Kun, WANG Zhangfei, ZHANG Yihui,

2021, 32(16):  1994-2001.  DOI: 10.3969/j.issn.1004-132X.2021.16.012

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The overlook of interference of drivers' behavior and environmental factors might cause human-computer conflicts during the transition from drive mode to assistance mode. A human-machine cooperative based lane keeping assist(LKA) control system was proposed to aid the issue, where a two degrees-of-freedom vehicle dynamics model was established and linear quadratic regulation lateral control algorithm was employed to determine vehicle's optimal front wheel angle. Vehicle deviation safety assessment model, torque control and safety exit strategy were implemented in the proposed LKA system to realize human-computer interaction and co-driving. A collaborative simulation was fulfilled in CarSim and  Simulink to validate the feasibility of LKA. As the feasibility was demonstrated, the LKA control system was further implemented on the JAC light truck to test the system safety performances. Both of the simulation and experimental results shows that better lane keeping and security performances are achieved with the proposed LKA system.

Fixed Abrasive Based Self-rotation Grinding for Single Crystal Sapphire

WU Ke, LU Xinming, MEHMOOD Awais, ZHOU Libo, YUAN Julong

2021, 32(16):  2002-2007，2015.  DOI: 10.3969/j.issn.1004-132X.2021.16.013

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A planarization method was presented for sapphire substrate with high quality and efficiency by applying fixed abrasive based diamond and chemo-mechanical grinding on self-rotation grinding platform. Diamond grinding wheel with different abrasive sizes was able to either obtain faster material removal rate or better surface quality. Then, high Cr2O3 abrasive concentrated wheel was developed, and chemo-mechanical grinding was applied for the planarization processes of sapphire substrate. Experimental result suggests that chemo-mechanical grinding is able to remove the surface and subsurface damages left by diamond grinding. The obtained sapphire substrate is with surface quality Ra less than 1 nm and no/little subsurface damages. Theoretical analysis to the grinding forces for single diamond particle reveals that particle size is the most influential factor on material removal rate and surface quality. The solid phase reaction between Cr2O3 and sapphire was demonstrated by XPS analysis.

Embedded Position Optimization of Cables in Cables-Carbon Fiber Reinforced Composite Integrated Components Based on Improved Response Surface Methodology

YANG Xu, ZHOU Dejian, ZHUANG Gongwei, SONG Wei, LIU Xiaolong, SHE Yulai

2021, 32(16):  2008-2015.  DOI: 10.3969/j.issn.1004-132X.2021.16.014

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Aiming at the problems that were difficult to determine the cable location parameters of cables-carbon fiber reinforced composite(CFRP) integrated components, the finite element analysis model and electromagnetic compatibility analysis model of the integrated components were established. An improved response surface method was proposed and used to solve the optimization problems of cables embedding location parameters. Finally, a set of high-quality cables embedding location parameters were predicted by considering the mechanics properties, EMC performances and manufacturing constraints. The verification results show that the integrated components obtained by using these parameters may meet all the constraints, the average error between the predicted and actual values of all responses is as 3%, and the embedded cables has little effect on the mechanics properties of CFRP matrix.