Table of Content

25 February 2019, Volume 30 Issue 04

Previous Issue    Next Issue

A New Gravity Compensation Method of Space-borne Perimeter Truss Deployable Reflectors

2019, 30(04):  379-384. 

Asbtract ( )   HTML   PDF (647KB) ( )  

References | Related Articles | Metrics

To solve the problems of the deviation of slings and the deficiency of vertical force caused by non plumb-bob effects of slings in the experiments of perimeter truss deployable reflectors in space orbit, a gravity compensation method was proposed herein with active horizontal positioning and moving slings. Firstly, the relationships between the horizontal displacement of truss nodes and truss deployment angles were obtained by kinematic analyses of the deployment processes, so that the positions of the truss nodes could be followed in deployment processes accurately. Furthermore, static mechanics analyses of the deployment processes were carried out to determine the masses of counterweights. Finally, the rationality and correctness of the proposed method were verified by comparing with the hanging wire counterweight method based on ADAMS.

Energy Dissipation Analysis of Forging Manipulator Hydraulic Systems in Stretching Processes

YAO Jing1,2,3;LI Yao3;ZHAI Fugang3;ZHU Hanyin3;ZHANG Yin4

2019, 30(04):  385-392. 

Asbtract ( )   HTML   PDF (796KB) ( )  

References | Related Articles | Metrics

For the purposes of providing guidance for optimization of hydraulic control systems and energy saving control methods for forging manipulators, the model of energy flow and calculation model of energy for forging manipulators were extended, and the control characteristics and energy dissipation characteristics of forging manipulator hydraulic systems were analyzed under stretching processes. The distribution laws of energy dissipation in hydraulic systems were found out, and the key points of low energy efficiency were analyzed. The results show that the energy dissipation characteristics of the forging manipulator hydraulic systems have following features. The energy transfer efficiency of clamp lifting and rotation may be higher than 60%. The energy transfer efficiency of walking motion of cart is only 17%. When the clamp drops, the gravitational potential energy is almost converted to the throttling losses of the lift control valves. If single system pressure driving mode does not match different loads of multi actuator reasonably, there will be huge throttling losses.

Lane Detection Algorithm Based on Projection Statistics and Hyperbolic Fitting

WANG Qidong1,2;WEI Zhenya1;WANG Naihan1;CHEN Wuwei1;XIE Youhao3

2019, 30(04):  393-399. 

Asbtract ( )   HTML   PDF (772KB) ( )  

References | Related Articles | Metrics

A lane detection algorithm was proposed based on projection and hyperbolic fitting. Firstly, the collected images were preprocessed, and the feature points of lane marks were extracted by the informations such as the widths of lane lines. Secondly, the vanishing points were located according to the positions and the direction angles of feature points, lanes of near field were extracted based on the vanishing points, and then supplemented the lane. Finally, lanes of near field information and hyperbolic fitting were used to find the best lanes where there were a crooked road. The experimental results show that the algorithm proposed herein may effectively detect the lanes with different curvatures, and the proposed lane detection method has high accuracy rate. The algorithm exhibits high robustness under various environments.

Design and Optimization of Electropermanent Magnet Suckers in Horizontal Well Tractors

CHANG Xu1;YANG Dongchao1;SUN Keping1;ZHANG Fuxing2;LI Hongjun2

2019, 30(04):  399-405. 

Asbtract ( )   HTML   PDF (847KB) ( )  

References | Related Articles | Metrics

Most tractors used two motors to control, and led to high energy consumption, large heat release and complex control. Due to these problems, an electropermanent magnet sucker was designed to provide enough normal forces between wheels and the pipe walls. So, the tractor might be drived by only one motor. The finite element method was used to simulate the electropermanent magnet suckers, which analyzed the impacts of various size parameters on the magnetization and demagnetization performances. Based on the simulation results, a group of reasonable size parameters was selected. The errors between the actual values and the simulated values are less than 15% by the experiments of the electropermanent magnet sucker, and the well tractor with electropermanent magnet sucker may drag over 3 000N.

Bearing Fault Diagnosis Based on K-SVD and HBW-OOMP

ZHANG Wenhao1;LI Yongjian2，3;ZHANG Weihua1

2019, 30(04):  406-412. 

Asbtract ( )   HTML   PDF (722KB) ( )  

References | Related Articles | Metrics

A new method for fault diagnosis of bearings was presented based on K-SVD and HBW-OOMP. Firstly,K-SVD dictionary training algorithm was utilized to construct a redundant dictionary containing impulsive components and the disadvantages of less adaptability of fixed structure dictionary were overcome. Then, HBW-OOMP algorithm was employed in selecting the best atom and solving the sparse coefficients. The signals were decomposed adaptively with the maximum principle of the envelop spectrum kurtosis. The fault features were extracted by the proposed method from simulated and experimental signals respectively. The results show that the method may achieve  the extraction of impulsive components from strong noise, which demonstrates the effectiveness and practicability.

Topology and Kinematics Design of Spatially nT1R-type Reconfigurable and Partial Motion Decoupling Parallel Mechanism

SHEN Huiping;ZHAO Yingchun;XU Ke;ZHANG Zhen;YANG Tingli

2019, 30(04):  413-422. 

Asbtract ( )   HTML   PDF (788KB) ( )  

References | Related Articles | Metrics

According to the design theory for parallel mechanism based on positions and orientation characteristics (POC), a new 3-DOF PM with reconfigurable moving platform RPa3R-R+RSS, was proposed． Firstly, the output characteristics of the PM were analyzed, which show that the moving platform may produce n-translation and 1-rotation (nT1R, n=2,3) and has partial motion decoupling. The PM may produce a specific rotational output motion around one of three specific axes x, y, z by reconfigurable architecture of the moving platform. The degree of freedom and the coupling degree of the PM were calculated. Secondly, a general kinematics model of the PM for a configuration of arbitrary rotational shaft of the moving platform was established according to the kinematic molding principles based on the ordered single-open-chain（SOC） units. Lastly, the kinematics of the output configuration of moving platform with rotating around the z axis were analyzed, including the positive and inverse position solutions, workspace, rotation capability, singularity conditions, and the calculation and simulation of  velocity and acceleration.

Analysis of 3-UPS/S Parallel Platform Vibration Responses under Hydraulic Servo Drives

LI Yukun1,2;LI Yongquan1,2;WAN Yixin1,2;QIANG Hongbin2,3;ZHANG Lijie2,3

2019, 30(04):  423-430. 

Asbtract ( )   HTML   PDF (960KB) ( )  

References | Related Articles | Metrics

Considering the vibration problems of parallel stabilized platforms in heavy loading, a 3-UPS/S parallel stabilized platform driven by hydraulic servo was studied. Based on the principles of virtual work, the dynamics model of the stabilized platform was established. Considering the actual working conditions, the dynamics model was simplified to obtain the vibration model of the stable platform. In order to improve the reliability of the calculation, experiments were carried out to obtain the actual stiffness of a single branch. Based on this, the stabilized platform modal tests were carried out by using pulse excitation method, the correctness of the vibration model was verified by comparing the measured values and theoretical values of natural frequencies. Finally, the influences of hydraulic cylinder vibrations on the movement of the moving platform and vibration responses of moving platform were analyzed under no-load and load. According to the analyses and calculations, the poor stability of the mechanisms is mainly caused by the vibrations of the hydraulic cylinders and the forced vibrations of the moving platforms under heavy loads.

Optimal Design for Electromagnetic Driven Systems of Bladder Power Pumps

CAO Rui1;LI Xiao1;GUAN Ting2;XIAO Yuansong2

2019, 30(04):  431-437,447. 

Asbtract ( )   HTML   PDF (986KB) ( )  

References | Related Articles | Metrics

An optimization model of electromagnetic driven system of bladder power pump was built based on the theory of electromagnet design and optimization theory.The optimal structure design parameters were obtained by SQP method.According to these parameters,3D models of the electromagnetic driven systems and bladder power pumps were established.The electromagnetic driven performance,the temperature rise performance and the micturition performance were simulated by using ANSYS Workbench.The simulation and experimental results show that the optimization model and 3D finite element(FE) models are effective and practical. Comparing with the formers, the volume of electromagnet is reduced by 65.45%,the weight of electromagnet is reduced by 60.25%,the electromagnetic driven force is increased by 2.09%,the maximum of intravesical pressure is increased by 2.74%,the maximum of urine flow rate is increased by 14.22%,the temperature rise is increased 1.64 ℃.The results improve the micturition performance.The research may provide theoretical and technical guidance for the design of portable,reliable and suitable for animal and clinical studies of the bladder power pumps.

Integrated Scheduling of Multiple AGVs and Machines in Flexible Job Shops

HE Changzheng1;SONG Yuchuan1;LEI Qi1;LYU Xiangfei1;LIU Ruanxiang1;CHEN Jin2

2019, 30(04):  438-447. 

Asbtract ( )   HTML   PDF (894KB) ( )  

References | Related Articles | Metrics

For the flexible job shop-scheduling problem with AGVs, a hybrid genetic algorithm was proposed based on the time window and Dijkstra algorithm. Firstly, a mathematical model of the dual resource scheduling of AGV/machine was established. Secondly, three solutions were used to deal with conflicts and collisions in multiple AGV path planning. Then in order to take integrated scheduling of machine and AGVs into account, three encoding chain structures and the crossover and mutation operators of AGV coding chain were designed. Meanwhile, the Dijkstra algorithm was combined with the time window principles in the decoding operations of genetic algorithm, which may accurately plan a shortest path without collisions and conflicts for the taskes of AGVs. Finally, the feasibility, effectiveness and superiority of this algorithm were verified by numerical examples.

Dynamic Simulation and Optimization of Pneumatic Tendon Ejection Systems for Small UAVs

HUANG Guoqin1, 2;LUO Shaqi1, 2;YU Jin1, 2

2019, 30(04):  448-454. 

Asbtract ( )   HTML   PDF (776KB) ( )  

References | Related Articles | Metrics

Aiming at the disadvantages of high impact, large mass and poor dynamic characteristics of impact cylinder UAV ejection system, a bionic pneumatic muscle driven UAV ejection system was proposed. By the method of utilizing the small nonlinearity of pneumatic tendons and configuring the wedge angles, the project may ameliorate the stress conditions of the UAVs and slow down the acceleration fluctuation. The mathematical modeling and dynamic analysis of the ejection system were carried out, and the Simulink model was built to emulate the system. Combing the MATLAB and Simulink, the existing acceleration trajectories were further optimized by multi-objective genetic algorithm. The optimized acceleration track may improve the acceleration mean, the energy utilization rate of the pneumatic muscle and the take-off speed. At the same time, the acceleration peak values are reduced, and the acceleration fluctuations are reduced by 76.79% on the original basis. Simulation and optimization results show that the system may avoid the disadvantages of impact cylinder ejection system, and make the acceleration changes smoothly and reduce the maximum overload of the whole systems.

Visual Inspection for Extended Edge Belt Tearing  Based on SVM

WANG Fubin1,2;SUN Haiyang1;TU Paul 2

2019, 30(04):  455-460. 

Asbtract ( )   HTML   PDF (679KB) ( )  

References | Related Articles | Metrics

A belt safety monitoring method was proposed based on vision, and a visual monitoring system for belt tearing was constructed. Aiming at the image degradation from interference during operations of belt conveyor, Wiener filtering method was used to restore the degraded images. In order to recognize the belt cracks with high-speed moving in real time, CamShift algorithm was used to track and capture the targets of fast-moving sequence images of belt cracks. Canny operator was used to extract the edges of belt cracks, and the detected edges of belt cracks were expented outwards by adding a value δ, increasing the weights of the detected cracks, and more robust edge detection results were obtained. Finally, belt crack prediction model was constructed based on SVM, geometric characteristics, such as pixel area and length width ratio of the belt crack images were taken as the model inputs to predict belt crack states. Experimental results show the effectiveness of the method of belt tearing detection method proposed herein.

Motion Simulation Technology for Automatic Drilling and Riveting Off-line Programming Systems

LIU Liansheng1;WANG Min1;SUN Jinping2;WANG Hui1;DING Liping1

2019, 30(04):  461-466. 

Asbtract ( )   HTML   PDF (625KB) ( )  

References | Related Articles | Metrics

According to the structure and movement characteristics of five-axis automatic drilling and riveting systems, the off-line programming system architecture of automatic drilling and riveting was constructed, and the motion simulation module was developed. Firstly, considering that the characteristics of all points were relatively fixed in bracket coordinate system, an inverse kinematics solution was proposed based on the moving coordinate system’s point positions. Based on this, a real-time interference detection route planing algorithm was proposed.Then, motion simulations were realized in DMU module of CATIA by CAA secondary development method. Lastly, an example of aircraft panel part was given to demonstrate the feasibility of this system. The results indicate that it may effectively identify interference parts and avoid interference by inserting viaing points.

Storage Position Intelligent Optimization for Cantilever Rack Stereoscopic Warehouses

ZHANG Lei1,2;LENG Jiewu1,2;GONG Yue1,2

2019, 30(04):  467-471,479. 

Asbtract ( )   HTML   PDF (545KB) ( )  

References | Related Articles | Metrics

The structures and storage characteristics of a cantilever rack stereoscopic warehouse was analyzed, a multi-objective mathematical model was built based on the maximization of the utilization rate of the stereoscopic warehouses and the stability optimization of the cantilever rack stereoscopic warehouses, and intelligent algorithm was used to optimize analyses. Finally, through the simulation, the results show that the algorithm is effective, and the multiple population genetic algorithm is proved more suitable than simple genetic algorithm in solving the storage position optimization for cantilever rack stereoscopic warehouses.

Rescheduling Mode Selection under Recessive Disturbance Accumulation via Machine Learning

TANG Qiuhua1,2,3;CHENG Lixin1,2,3 ;ZHANG Liping1,2,3

2019, 30(04):  472-479. 

Asbtract ( )   HTML   PDF (874KB) ( )  

References | Related Articles | Metrics

A method of rescheduling mode selection was proposed to solve the problems of disturbance cumulative rescheduling scheme selection based on data learning. The cumulative disturbance time was used to quantify the implicit disturbance, and the real-time production and processing status were reflected by data. The cumulative disturbance rescheduling model was constructed, and the factors and decision labels of rescheduling decision were obtained based on genetic simulation. The characteristics of the simulation samples were analyzed, and based on the data feature reduction mapping, the SVM-based classification decision model was constructed to learn the internal relationship between the production situation and the rescheduling mode, which would help the production managers to make the decision quickly and improve the response speed. Finally, the rationality and effectiveness of the rescheduling selection framework were verified by experiments.

Reliability-based Design Optimization of Milling Process Parameters Using Approximate Model

SHANG Baoping1;YAN Fuhong1;LIU Gaofeng2;CHEN Zhenzhong3;QIU Haobo4;LI Xiaoke1

2019, 30(04):  480-485,493. 

Asbtract ( )   HTML   PDF (625KB) ( )  

References | Related Articles | Metrics

The uncertainties of design parameters were not considered in the existing milling process parameter optimization methods, resulting in the optimization results difficult to meet the performance requirements of the actual products. The reliability-based design optimization method was used to determine the optimal milling process parameters. In the proposed method, the surface roughness was the objective function, and the reliability that the maximum milling force less than the given value was taken as the constraint. Considering the variations of milling speeds and feeds per tooth, a reliability optimization model of milling process parameters was established, Kriging approximation and radial basis function approximation were used to replace the implicit relationships of milling surface roughness, milling force and design variables. Finally, Monte Carlo simulation-sequential approximation programming was used to solve the optimal design of the proposed model. The reliability optimization results were verified through milling experiments. The results show that this method may effectively reduce the milling surface roughness and ensure the reliability requirements of the maximum milling force.

Process of Molecular Dynamics Simulation of Nanojoining Processes

LI Hong1;YUAN Junli1;LI Zhuoxin1;TILLMANN Wolfgang2;HU Anming1,3

2019, 30(04):  486-493. 

Asbtract ( )   HTML   PDF (731KB) ( )  

References | Related Articles | Metrics

Nano materials were widely used because of their unique structures and properties,and nano joining technology was also developed.In the field of nanofabrication，although there were many varieties of advanced microscopy methods,it was difficult to observe and analyze many phenomenons and behaviors of nano materials by experiments due to the restrictions of real-time observation.Molecular dynamics simulation within nanometer spatial scales and nanoseconds time scale allowed insight into molecular motions on an atomic scale since it was consistent with the time and spatial scales of many processes in nanofabrication.Therefore,it was feasible to use molecular dynamics simulation to simulate the properties of nanomaterials and the dynamic behavior of atoms in the nano joining processes. Herein,the progresses of molecular dynamics simulation of nano-scale materials,including nanomultilayers,nanowires,carbon nanotubes and nanoparticles in the nanojoining processes,as well as applications of these materials for joining of large size materials were reviewed. Meanwhile it is illustrated that the simulation results are in good agreement with the experimental ones.The existing problems,possible solutions and development trends were discussed.

Flexible Punching System Using Industrial Robots for Automotive Panels

YIN Guotao1;ZHU Zhenghe2;GONG Hu1;LU Zhenfeng2;YONG Huashan2;LIU Lei3;HE Wei3

2019, 30(04):  494-497,402. 

Asbtract ( )   HTML   PDF (667KB) ( )  

References | Related Articles | Metrics

With the development of tailor-made automotive panels,a new flexible punching system was proposed for personalization punching of automotive panels based on 6-axis industrial robots.Meanwhile,in order to get accurate and non-interference punching trajectory,the interactive tool path generation method was proposed in 2D planes based on shape features of punching pliers.This system is highly flexible and can be adjusted easily to punch all kinds of holes in different positions.