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Reconfigurable mechanism-based metamaterials for ternary-coded elastic wave polarizers and programmable refraction control
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作者 Zhou HU Zhibo WEI +1 位作者 Yan CHEN Rui ZHU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第7期1225-1242,共18页
Elastic metamaterials with unusual elastic properties offer unprecedented ways to modulate the polarization and propagation of elastic waves.However,most of them rely on the resonant structural components,and thus are... Elastic metamaterials with unusual elastic properties offer unprecedented ways to modulate the polarization and propagation of elastic waves.However,most of them rely on the resonant structural components,and thus are frequency-dependent and unchangeable.Here,we present a reconfigurable 2D mechanism-based metamaterial which possesses transformable and frequency-independent elastic properties.Based on the proposed mechanism-based metamaterial,interesting functionalities,such as ternarycoded elastic wave polarizer and programmable refraction,are demonstrated.Particularly,unique ternary-coded polarizers,with 1-trit polarization filtering and 2-trit polarization separating of longitudinal and transverse waves,are first achieved.Then,the strong anisotropy of the proposed metamaterial is harnessed to realize positive-negative bi-refraction,only-positive refraction,and only-negative refraction.Finally,the wave functions with detailed microstructures are numerically verified. 展开更多
关键词 elastic metamaterial elastic wave reconfigurable design zero mode ternary code programmable refraction
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A Survey of Mathematical Tools in Topology and Performance Integrated Modeling and Design of Robotic Mechanism 被引量:1
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作者 Xinming Huo Shuofei Yang +2 位作者 Binbin Lian Tao Sun Yimin Song 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2020年第4期30-44,共15页
Topology and performance are the two main topics dealt in the development of robotic mechanisms.However,it is still a challenge to connect them by integrating the modeling and design process of both parts in a unified... Topology and performance are the two main topics dealt in the development of robotic mechanisms.However,it is still a challenge to connect them by integrating the modeling and design process of both parts in a unified frame.As the properties associated with topology and performance,finite motion and instantaneous motion of the robot play key roles in the procedure.On the purpose of providing a fundamental preparation for integrated modeling and design,this paper carries out a review on the existing unified mathematic frameworks for motion description and computation,involving matrix Lie group and Lie algebra,dual quaternion and pure dual quaternion,finite screw and instantaneous screw.Besides the application in robotics,the review of the work from these mathematicians concentrates on the description,composition and intersection operations of the finite and instantaneous motions,especially on the exponential-differential maps which connect the two sides.Furthermore,an in-depth discussion is worked out by investigating the algebraical relationship among these methods and their further progress in integrated robotic development.The presented review offers insightful investigation to the motion description and computation,and therefore would help designers to choose appropriate mathematical tool in the integrated design and modeling and design of mechanisms and robots. 展开更多
关键词 Robotic mechanism Integrated method Matrix Lie group Dual quaternion Finite screw
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A Finite and Instantaneous Screw Based Approach for Topology Design and Kinematic Analysis of 5-Axis Parallel Kinematic Machines 被引量:9
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作者 Tao Sun Shuo-Fei Yang +1 位作者 Tian Huang Jian S.Dai 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2018年第2期66-75,共10页
Unifying the models for topology design and kinematic analysis has long been a desire for the research of parallel kinematic machines(PKMs). This requires that analytical description, formulation and operation for bot... Unifying the models for topology design and kinematic analysis has long been a desire for the research of parallel kinematic machines(PKMs). This requires that analytical description, formulation and operation for both finite and instantaneous motions are performed by the same mathematical tool. Based upon finite and instantaneous screw theory, a unified and systematic approach for topology design and kinematic analysis of PKMs is proposed in this paper. Using the derivative mapping between finite and instantaneous screws built in the authors’ previous work, the finite and instantaneous motions of PKMs are analytically described by the simple and non?redundant screws in quasi?vector and vector forms. And topological and parametric models of PKMs are algebraically formulated and related. These related topological and parametric models are ready to do type synthesis and kinematic analysis of PKMs under the unified framework of screw theory. In order to show the validity of the proposed approach, a kind of two?translational and three?rotational(2T3R)5?axis PKMs is taken as example. Numerous new structures of the 2T3R PKMs are synthe?sized as the results of topology design, and their Jacobian matrix is obtained easily for parameter optimization and performance evaluation. Some of the synthesized PKMs have outstanding capabilities in terms of large workspaces and flexible orientations, and have great potential for industrial applications of machining and manufacture. Among them, METROM PKM is a typical example which has attracted a lot of attention from global companies and already been developed as commercial products. The approach is a general and unified approach that can be used in the innovative design of different kinds of PKMs. 展开更多
关键词 Innovative design Parallel kinematic machines Screw theory Finite screw Instantaneous screw
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Design of a Flexible Capture Mechanism Inspired by Sea Anemone for Non-cooperative Targets 被引量:2
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作者 Jiankun Yang Chengwei Ren +3 位作者 Chenghao Yang Youyu Wang Shumin Wan Rongjie Kang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2021年第4期236-248,共13页
Robotic grippers have been used in industry as end-effectors but are usually limited to operations in pre-defined workspace.However,few devices can capture irregularly shaped dynamic targets in space,underwater and ot... Robotic grippers have been used in industry as end-effectors but are usually limited to operations in pre-defined workspace.However,few devices can capture irregularly shaped dynamic targets in space,underwater and other unstructured environments.In this paper,a novel continuum arm group mechanism inspired by the morphology and motions of sea anemones is proposed.It is able to dissipate and absorb the kinetic energy of a fast moving target in omni-direction and utilize multiple arms to wrap and lock the target without accurate positioning control.Wire-driven actuation systems are implemented in the individual continuum arms,achieving both bending motion and stiffness regulation.Through finite element method,the influence of different configurations of the continuum arm group on the capture performance is analyzed.A robotic prototype is constructed and tested,showing the presented arm group mechanism has high adaptability to capture targets with different sizes,shapes,and incident angles. 展开更多
关键词 Non-cooperative targets Continuum arm group Wire-driven mechanism
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Analysis of Frequency Characteristics and Sensitivity of Compliant Mechanisms 被引量:7
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作者 LIU Shanzeng DAI Jiansheng +3 位作者 LI Aimin SUN Zhaopeng FENG Shizhe CAO Guohua 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第4期680-693,共14页
Based on a modified pseudo-rigid-body model,the frequency characteristics and sensitivity of the large-deformation compliant mechanism are studied.Firstly,the pseudo-rigid-body model under the static and kinetic condi... Based on a modified pseudo-rigid-body model,the frequency characteristics and sensitivity of the large-deformation compliant mechanism are studied.Firstly,the pseudo-rigid-body model under the static and kinetic conditions is modified to enable the modified pseudo-rigid-body model to be more suitable for the dynamic analysis of the compliant mechanism.Subsequently,based on the modified pseudo-rigid-body model,the dynamic equations of the ordinary compliant four-bar mechanism are established using the analytical mechanics.Finally,in combination with the finite element analysis software ANSYS,the frequency characteristics and sensitivity of the compliant mechanism are analyzed by taking the compliant parallel-guiding mechanism and the compliant bistable mechanism as examples.From the simulation results,the dynamic characteristics of compliant mechanism are relatively sensitive to the structure size,section parameter,and characteristic parameter of material on mechanisms.The results could provide great theoretical significance and application values for the structural optimization of compliant mechanisms,the improvement of their dynamic properties and the expansion of their application range. 展开更多
关键词 compliant mechanism pseudo-rigid-body model frequency characteristic sensitivity analysis finite element analysis
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Test Verification and Design of the Bicycle Frame Parameters 被引量:1
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作者 ZHANG Long XIANG Zhongxia +1 位作者 LUO Huan TIAN Guan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第4期716-725,共10页
Research on design of bicycles is concentrated on mechanism and auto appearance design, however few on matches between the bike and the rider. Since unreasonable human-bike relationship leads to both riders' worn-out... Research on design of bicycles is concentrated on mechanism and auto appearance design, however few on matches between the bike and the rider. Since unreasonable human-bike relationship leads to both riders' worn-out joints and muscle injuries, the design of bicycles should focus on the matching. In order to find the best position of human-bike system, simulation experiments on riding comfort under different riding postures are done with the lifemode software employed to facilitate the cycling process as well as to obtain the best position and the size function of it. With BP neural network and GA, analyzing simulation data, conducting regression analysis of parameters on different heights and bike frames, the equation of best position of human-bike system is gained at last. In addition, after selecting testers, customized bikes based on testers' height dimensions are produced according to the size function. By analyzing and comparing the experimental data that are collected from testers when riding common bicycles and customized bicycles, it is concluded that customized bicycles are four times even six times as comfortable as common ones. The equation of best position of human-bike system is applied to improve bikes' function, and the new direction on future design of bicycle frame parameters is presented. 展开更多
关键词 bike modeling data mining FATIGUE dynamics simulation oxygen uptake
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Deployment Dynamic Modeling and Driving Schemes for a Ring-Truss Deployable Antenna
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作者 Baiyan He Lijun Jia +3 位作者 Kangkang Li Rui Nie Yesen Fan Guobiao Wang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第4期163-182,共20页
Mesh reflector antennas are widely used in space tasks owing to their light weight,high surface accuracy,and large folding ratio.They are stowed during launch and then fully deployed in orbit to form a mesh reflector ... Mesh reflector antennas are widely used in space tasks owing to their light weight,high surface accuracy,and large folding ratio.They are stowed during launch and then fully deployed in orbit to form a mesh reflector that transmits signals.Smooth deployment is essential for duty services;therefore,accurate and efficient dynamic modeling and analysis of the deployment process are essential.One major challenge is depicting time-varying resistance of the cable network and capturing the cable-truss coupling behavior during the deployment process.This paper proposes a general dynamic analysis methodology for cable-truss coupling.Considering the topological diversity and geometric nonlinearity,the cable network's equilibrium equation is derived,and an explicit expression of the time-varying tension of the boundary cables,which provides the main resistance in truss deployment,is obtained.The deployment dynamic model is established,which considers the coupling effect between the soft cables and deployable truss.The effects of the antenna's driving modes and parameters on the dynamic deployment performance were investigated.A scaled prototype was manufactured,and the deployment experiment was conducted to verify the accuracy of the proposed modeling method.The proposed methodology is suitable for general cable antennas with arbitrary topologies and parameters,providing theoretical guidance for the dynamic performance evaluation of antenna driving schemes. 展开更多
关键词 Cable antenna Deployment dynamics Performance evaluation Driving scheme Deployable structure
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Grinding/Cutting Technology and Equipment of Multi-scale Casting Parts
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作者 Meng Wang Yimin Song +2 位作者 Panfeng Wang Yuecheng Chen Tao Sun 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第5期38-46,共9页
Multi-scale casting parts are important components of high-end equipment used in the aerospace,automobile manufacturing,shipbuilding,and other industries.Residual features such as parting lines and pouring risers that... Multi-scale casting parts are important components of high-end equipment used in the aerospace,automobile manufacturing,shipbuilding,and other industries.Residual features such as parting lines and pouring risers that inevitably appear during the casting process are random in size,morphology,and distribution.The traditional manual processing method has disadvantages such as low efficiency,high labor intensity,and harsh working environment.Existing machine tool and serial robot grinding/cutting equipment do not easily achieve high-quality and high-efficiency removal of residual features due to poor dexterity and low stiffness,respectively.To address these problems,a five-degree-of-freedom(5-DoF)hybrid grinding/cutting robot with high dexterity and high stiffness is proposed.Based on it,three types of grinding/cutting equipment combined with offline programming,master-slave control,and other technologies are developed to remove the residual features of small,medium,and large casting parts.Finally,the advantages of teleoperation processing and other solutions are elaborated,and the difficulties and challenges are discussed.This paper reviews the grinding/cutting technology and equipment of casting parts and provides a reference for the research on the processing of multi-scale casting parts. 展开更多
关键词 Multi-scale casting parts Residual features 5-DoF hybrid grinding/cutting robot Teleoperation processing
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Forming-Precision-Driven Structure Design of Hydraulic Press: Methodology and Case Study
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作者 李艳聪 张连洪 +2 位作者 何柏岩 陈永亮 张淳 《Transactions of Tianjin University》 EI CAS 2015年第6期541-553,共13页
The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined... The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined, resulting in poor designs with insufficient or over sufficient stiffness of press structures. In this paper, an approach for the structure design of hydraulic presses is proposed, which is forming-precision-driven and can make presses costeffective by lightweight optimization. The approach consists of five steps:(1)the determination of the press stiffness specification in terms of the forming precision requirement of workpieces;(2)the conceptual design of the press structures according to the stiffness and workspace specifications, and the structure configuration of the press;(3)the prototype design of the press structures by equivalently converting the conceptual design to prototypes;(4)the selection of key structure parameters by sensitivity analysis of the prototype design; and(5)the optimization of the prototype design. The approach is demonstrated and validated through a case study of the structure design of a 100 MN hydraulic press. 展开更多
关键词 hydraulic press structure design precision forming conceptual design prototype design optimal design
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Type Synthesis of 1T2R Parallel Mechanisms Using Structure Coupling-Reducing Method 被引量:10
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作者 Haitao Liu Ke Xu +2 位作者 Huiping Shen Xianlei Shan Tingli Yang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2019年第5期70-79,共10页
Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms.Therefore,the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of intere... Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms.Therefore,the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest.Based on this purpose,this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism.With the aid of the theory of mechanism topology,the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented,which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism.Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed,resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree.One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics.The process of type synthesis is in the order of permutation and combination;therefore,there are no omissions.This method is also appli cable to other configurations,and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method. 展开更多
关键词 TYPE synthesis STRUCTURE coupling-reducing Coupling degree Parallel mechanism
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Coordinate Control,Motion Optimization and Sea Experiment of a Fleet of Petrel-Ⅱ Gliders 被引量:5
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作者 Dong-Yang Xue Zhi-Liang Wu +1 位作者 Yan-Hui Wang Shu-Xin Wang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2018年第1期127-141,共15页
The formation of hybrid underwater gliders has advantages in sustained ocean observation with high resolution and more adaptation for complicated ocean tasks. However, the current work mostly focused on the traditiona... The formation of hybrid underwater gliders has advantages in sustained ocean observation with high resolution and more adaptation for complicated ocean tasks. However, the current work mostly focused on the traditional gliders and AUVs.The research on control strategy and energy consumption minimization for the hybrid gliders is necessary both in methodology and experiment. A multi-layer coordinate control strategy is developed for the fleet of hybrid underwater gliders to control the gliders’ motion and formation geometry with optimized energy consumption. The inner layer integrated in the onboard controller and the outer layer integrated in the ground control center or the deck controller are designed. A coordinate control model is proposed based on multibody theory through adoption of artificial potential fields. Considering the existence of ocean flow, a hybrid motion energy consumption model is constructed and an optimization method is designed to obtain the heading angle, net buoyancy, gliding angle and the rotate speed of screw propeller to minimize the motion energy with consideration of the ocean flow. The feasibility of the coordinate control system and motion optimization method has been verified both by simulation and sea trials. Simulation results show the regularity of energy consumption with the control variables. The fleet of three Petrel-Ⅱ gliders developed by Tianjin University is deployed in the South China Sea. The trajectory error of each glider is less than 2.5 km, the formation shape error between each glider is less than 2 km, and the difference between actual energy consumption and the simulated energy consumption is less than 24% actual energy. The results of simulation and the sea trial prove the feasibility of the proposed coordinate control strategy and energy optimization method. In conclusion, a coordinate control system and a motion optimization method is studied, which can be used for reference in theoretical research and practical fleet operation for both the traditional gliders and hybrid gliders. 展开更多
关键词 Underwater glider Petrel-Ⅱ Coordinate control Path planning Artificial potential fields(APFs) Energy consumption
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Analysis and Comparison of Safety and Fatigue Comfort of Postal Bicycles Based on Finite Element Method and sEMG 被引量:5
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作者 项忠霞 李亚南 +1 位作者 田冠 常振元 《Transactions of Tianjin University》 EI CAS 2013年第4期272-278,共7页
The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) e... The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory. 展开更多
关键词 postal bicycle surface electromyogram signal evaluation index fatigue comfort finite element analysis
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Motion Analysis and Trials of the Deep Sea Hybrid Underwater Glider Petrel-Ⅱ 被引量:4
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作者 LIU Fang WANG Yan-hui +1 位作者 WU Zhi-liang WANG Shu-xin 《China Ocean Engineering》 SCIE EI CSCD 2017年第1期55-62,共8页
A hybrid underwater glider Petrel-II has been developed and field tested. It is equipped with an active buoyancy unit and a compact propeller unit. Its working modes have been expanded to buoyancy driven gliding and p... A hybrid underwater glider Petrel-II has been developed and field tested. It is equipped with an active buoyancy unit and a compact propeller unit. Its working modes have been expanded to buoyancy driven gliding and propeller driven level-flight, which can make the glider work in strong currents, as well as many other complicated ocean environments. Its maximal gliding speed reaches 1 knot and the propelling speed is up to 3 knots. In this paper, a 3D dynamic model of Petrel-II is derived using linear momentum and angular momentum equations. According to the dynamic model, the spiral motion in the underwater space is simulated for the gliding mode. Similarly the cycle motion on water surface and the depth-keeping motion underwater are simulated for the level-flight mode. These simulations are important to the performance analysis and parameter optimization for the Petrel-II underwater glider. The simulation results show a good agreement with field trials. 展开更多
关键词 hybrid underwater glider dynamic model numerical simulation underwater vehicles
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Residual Vibration Reduction of High-Speed Pick-and-Place Parallel Robot Using Input Shaping 被引量:3
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作者 Xianlei Shan Yuhang Li +1 位作者 Haitao Liu Tian Huang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第1期62-69,共8页
Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach... Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach based on the input shaping technique is presented in this paper for suppressing the residual vibration in these parallel robots.After addressing the design principle of an input shaper for a parallel robot with flexible actuated joints,a robust optimal input shaper is developed by considering the configuration-dependent flexible modes and minimizing the maximum percentage of residual vibration at the end-effector.The input shaper allows a good overall performance to be achieved throughout the entire workspace.Experimental results on a 4-DOF SCARA-type parallel robot show that the residual vibration of the end-effector is dramatically reduced and the dynamic positioning accuracy of the robot significantly improved. 展开更多
关键词 Pick-and-place parallel robot Residual vibration reduction Input shaping
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Attitude Coordination of Multi-HUG Formation Based on Multibody System Theory 被引量:1
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作者 XUE Dong-yang WU Zhi-liang +2 位作者 QI Er-mai WANG Yan-hui WANG Shu-xin 《China Ocean Engineering》 SCIE EI CSCD 2017年第2期248-255,共8页
Application of multiple hybrid underwater gliders (HUGs) is a promising method for large scale, long-term ocean survey. Attitude coordination has become a requisite for task execution of multi-HUG formation. In this... Application of multiple hybrid underwater gliders (HUGs) is a promising method for large scale, long-term ocean survey. Attitude coordination has become a requisite for task execution of multi-HUG formation. In this paper, a multibody model is presented for attitude coordination among agents in the HUG formation. The HUG formation is regarded as a multi-rigid body system. The interaction between agents in the formation is described by artificial potential field (APF) approach. Attitude control torque is composed of a conservative torque generated by orientation potential field and a dissipative term related with angular velocity. Dynamic modeling of the multibody system is presented to analyze the dynamic process of the HUG formation. Numerical calculation is carried out to simulate attitude synchronization with two kinds of formation topologies. Results show that attitude synchronization can be fulfilled based on the multibody method described in this paper. It is also indicated that different topologies affect attitude control quality with respect to energy consumption and adjusting time. Low level topology should be adopted during formation control scheme design to achieve a better control effect. 展开更多
关键词 hybrid underwater gliders (HUGs) FORMATION attitude coordination multibody system Kane's equation
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Optimal Matching Analysis of Net Buoyancy and Pitching Angle for Underwater Gliders 被引量:1
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作者 YANG Ming LIANG Yan +1 位作者 WANG Yan-hui YANG Shao-qiong 《China Ocean Engineering》 SCIE EI CSCD 2022年第5期697-706,共10页
Control parameter optimization is an efficient way to improve the endurance of underwater gliders(UGs),which influences their gliding efficiency and energy consumption.This paper analyzes the optimal matching between ... Control parameter optimization is an efficient way to improve the endurance of underwater gliders(UGs),which influences their gliding efficiency and energy consumption.This paper analyzes the optimal matching between the net buoyancy and the pitching angle and proposes a segmented control strategy of Petrel-L.The optimization of this strategy is established based on the gliding range model of UG,which is solved based on the approximate model,and the variations of the optimal control parameters with the hotel load are obtained.The optimization results indicate that the segmented control strategy can significantly increase the gliding range when the optimal matching between the net buoyancy and the pitching angle is reached,and the increase rate is influenced by the hotel load.The gliding range of the underwater glider can be increased by 10.47%at a hotel load of 0.5 W.The optimal matching analysis adopted in this study can be applied to other UGs to realize endurance improvement. 展开更多
关键词 optimal matching analysis underwater glider approximate model technology gliding range model
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Assessment Method of Heavy NC Machine Reliability Based on Bayes Theory 被引量:1
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作者 张雷 王太勇 胡占齐 《Transactions of Tianjin University》 EI CAS 2016年第2期105-109,共5页
It is difficult to collect the prior information for small-sample machinery products when their reliability is assessed by using Bayes method. In this study, an improved Bayes method with gradient reliability(GR) resu... It is difficult to collect the prior information for small-sample machinery products when their reliability is assessed by using Bayes method. In this study, an improved Bayes method with gradient reliability(GR) results as prior information was proposed to solve the problem. A certain type of heavy NC boring and milling machine was considered as the research subject, and its reliability model was established on the basis of its functional and structural characteristics and working principle. According to the stress-intensity interference theory and the reliability model theory, the GR results of the host machine and its key components were obtained. Then the GR results were deemed as prior information to estimate the probabilistic reliability(PR) of the spindle box, the column and the host machine in the present method. The comparative studies demonstrated that the improved Bayes method was applicable in the reliability assessment of heavy NC machine tools. 展开更多
关键词 heavy NC machine reliability assessment Bayes method prior information
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The Tessellation Rule and Properties Programming of Origami Metasheets Built with a Mixture of Rigid and Non-Rigid Square-Twist Patterns
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作者 Jiayao Ma Shixi Zang +1 位作者 Yan Chen Zhong You 《Engineering》 SCIE EI CAS 2022年第10期82-92,共11页
Metamaterials constructed from origami units of different types and behaviors could potentially offer a broader scope of mechanical properties than those formed from identical unit types.However,the geometric design r... Metamaterials constructed from origami units of different types and behaviors could potentially offer a broader scope of mechanical properties than those formed from identical unit types.However,the geometric design rules and property programming methods for such metamaterials have yet to be extensively explored.In this paper,we propose a new kind of origami metasheet by incorporating a family of different square-twist units.The tessellation rule of these metasheets is established to allow compatible mountain-valley crease assignments and geometric parameters among neighboring units.We demonstrate through experiments that the energy,initial peak force,and maximum stiffness of the metasheets can be obtained by a summation of the properties of the constitutional units.Based on this,we are able to program the mechanical properties of the metasheets over a wide range by varying the types and proportions of the units,as well as their geometric and material parameters.Furthermore,for a metasheet with a fixed number of units,all the geometrically compatible tessellations can be folded out of the same pre-creased sheet material by simply changing the mountain-valley assignments,thereby allowing the properties of the metasheet to be re-programmed based on specific requirements.This work could inspire a new class of programmable origami metamaterials for current and future mechanical and other engineering applications. 展开更多
关键词 Origami metamaterials Metasheets Square-twist pattern Non-periodic tessellation PROGRAMMABILITY
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Investigation on Mesh and Sideband Vibrations of Helical Planetary Ring Gear Using Structure, Excitation and Deformation Symmetries
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作者 Shi-Yu Wang Chanannipat Meesap 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2018年第6期55-67,共13页
Time?variant excitations in planetary gear trains can cause excessive noise and vibration and even damage the system on a permanent basis. This paper focuses on the elastic vibrations of a helical planetary ring gear ... Time?variant excitations in planetary gear trains can cause excessive noise and vibration and even damage the system on a permanent basis. This paper focuses on the elastic vibrations of a helical planetary ring gear subjected to mesh and planet?pass excitations. Motivated by the structure, excitation and deformation symmetries, this paper proposes dual?frequency superposition and modulation methods to capture the mesh and sideband vibrations. The transi?tion between ring gear tooth and planet is introduced to address the excitations and vibrations. The phasing e ect of ring gear tooth and planet on various deformations is formulated. The inherent connections between the two types of vibrations are identified. The vibrations share identical exciting rules and the wavenumber and modulating signal order both equal the linear combination of tooth and planet counts. The results cover in?plane bending and extensional, out?of?plane bending and torsional deformations. Main findings are verified by numerical calculation and comparisons with the open literature. The analytical expressions can be used to determine whether the sideband is caused by component fault or only by elastic vibration. The methods can be extended to other power?transmission systems because little restriction is imposed during the analysis. 展开更多
关键词 Helical planetary ring gear Typical vibration modes Planet phasing SIDEBAND
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Design,Hydrodynamic Analysis,and Testing of a Bio-inspired Movable Bow Mechanism for the Hybrid-driven Underwater Glider
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作者 Yanhui Wang Yudong Guo +3 位作者 Shaoqiong Yang Tongshuai Sun Xi Wang Huihui Zhou 《Journal of Bionic Engineering》 SCIE EI CSCD 2023年第4期1493-1513,共21页
Hybrid-driven Underwater Glider(HUG)is a new type of underwater vehicle which integrates the functions of an Autonomous Underwater Glider(AUG)and an Autonomous Unmanned Vehicle(AUV).Although HUG has the characteristic... Hybrid-driven Underwater Glider(HUG)is a new type of underwater vehicle which integrates the functions of an Autonomous Underwater Glider(AUG)and an Autonomous Unmanned Vehicle(AUV).Although HUG has the characteristics of long endurance distance,its maneuverability still has room to be improved.This work introduces a new movement form of the neck of the underwater creature into HUG and proposes a parallel mechanism to adjust the attitude angle and displacement of the HUG’s bow,which can improve the steering maneuverability.Firstly,the influence of bow movement and rotation on the hydrodynamic force and flow field of the whole machine is analyzed by using the Computational Fluid Dynamics(CFD)method.The degree of freedom,attitude control range and movement amount of the Movable Bow Mechanism(MBM)are obtained,and then the design of MBM is completed based on these constraints.Secondly,the kinematic and dynamic models of MBM are established based on the closed vector method and the Lagrange equation,respectively,which are fully verified by comparing the results of simulation in Matlab and Adams software,then a Radial Basis Function(RBF)neural network adaptive sliding mode controller is designed to improve the dynamic response effect of the output parameters of MBM.Finally,a prototype of MBM is manufactured and assembled.The kinematic,dynamics model and controller are verified by experiments,which provides a basis for applying MBM in HUGs. 展开更多
关键词 Underwater glider Movable bow mechanism Hydrodynamic simulation Steering maneuverability
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