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Kinematics Analysis of Mechanisms Based on Virtual Assembly 被引量:6
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作者 ZHANG Zhixian LIU Jianhua NING Ruxin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第6期748-757,共10页
Currently, virtual assembly technology has attracted increasing attention due to considerations of solving assembly problems in virtual environment before actual assembly in manufactory. Previous studies on kinematic ... Currently, virtual assembly technology has attracted increasing attention due to considerations of solving assembly problems in virtual environment before actual assembly in manufactory. Previous studies on kinematic analysis of mechanism only aim at analyzing motion law of single mechanism, but can not simulate the multi-mechanisms motion process at the same time, let alone simulating the automatic assembly process of products in a whole assembly workshop. In order to simulate the assembly process of products in an assembly workshop and provide effective data for analyzing mechanical performance after finishing assembly simulation in virtual environment, this study investigates the kinematics analysis of mechanisms based on virtual assembly. Firstly, in view of the same function of the kinematic pairs and the assembly constraints on restricting the motion of components (subassembly or part), the method of identifying kinematic pairs automatically based on assembly constraints is presented. The information of kinematic pairs can be obtained through calculating the constraint degree of the assembly constraints. Secondly, the incidence matrix eliminating element method is proposed in order to search the information and establish the models of mechanisms automatically after finishing assembly simulation in virtual environment. Both methods have important significance for reducing the workload of pretreatment and promoting the level of automation of kinematics analysis. Finally, the method of kinematics analysis of mechanisms is presented. Based on Descartes coordinates, three types of kinematics equations are formed. The parameters, like displacement, velocity, and acceleration, can be obtained by solving these equations. All these data are important to analyze mechanical performance. All the methods are implemented and validated in the prototype system virtual assembly process planning(VAPP). The mechanism models are established and simulated in the VAPP system, and the result curves are shown accurately. The proposed kinematics analysis of mechanisms based on virtual assembly provides an effective method for simulating product assembly process automatically and analyzing mechanical performance after finishing assembly simulation. 展开更多
关键词 virtual assembly assembly constraint constraint degree eliminating element method kinematics equations kinematics analysis
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Explicit Symplectic Geometric Algorithms for Quaternion Kinematical Differential Equation 被引量:1
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作者 Hong-Yan Zhang Zi-Hao Wang +3 位作者 Lu-Sha Zhou Qian-Nan Xue Long Ma Yi-Fan Niu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第2期479-488,共10页
Solving quaternion kinematical differential equations(QKDE) is one of the most significant problems in the automation, navigation, aerospace and aeronautics literatures. Most existing approaches for this problem neith... Solving quaternion kinematical differential equations(QKDE) is one of the most significant problems in the automation, navigation, aerospace and aeronautics literatures. Most existing approaches for this problem neither preserve the norm of quaternions nor avoid errors accumulated in the sense of long term time. We present explicit symplectic geometric algorithms to deal with the quaternion kinematical differential equation by modelling its time-invariant and time-varying versions with Hamiltonian systems and adopting a three-step strategy. Firstly,a generalized Euler's formula and Cayley-Euler formula are proved and used to construct symplectic single-step transition operators via the centered implicit Euler scheme for autonomous Hamiltonian system. Secondly, the symplecticity, orthogonality and invertibility of the symplectic transition operators are proved rigorously. Finally, the explicit symplectic geometric algorithm for the time-varying quaternion kinematical differential equation, i.e., a non-autonomous and non-linear Hamiltonian system essentially, is designed with the theorems proved. Our novel algorithms have simple structures, linear time complexity and constant space complexity of computation. The correctness and efficiencies of the proposed algorithms are verified and validated via numerical simulations. 展开更多
关键词 Index Terms-Linear time-varying system navigation system quaternion kinematical differential equation (QKDE) real-timecomputation symplectic method.
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Design of dead reckoning system for mobile robot 被引量:3
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作者 于金霞 蔡自兴 +1 位作者 段琢华 邹小兵 《Journal of Central South University of Technology》 EI 2006年第5期542-547,共6页
A dead reckoning system for a wheeled mobile robot was designed, and the method for robot’s pose estimation in the 3D environments was presented on the basis of its rigid-body kinematic equations. After analyzing the... A dead reckoning system for a wheeled mobile robot was designed, and the method for robot’s pose estimation in the 3D environments was presented on the basis of its rigid-body kinematic equations. After analyzing the locomotion architecture of mobile robot and the principle of proprioceptive sensors, the kinematics model of mobile robot was built to realize the relative localization. Considering that the research on dead reckoning of mobile robot was confined to the 2 dimensional planes, the locomotion of mobile robot in the 3 coordinate axis direction was thought over in order to estimate its pose on uneven terrain. Because the computing method in a plane is rather mature, the calculation in height direction is emphatically represented as a key issue. With experimental results obtained by simulation program and robot platform, the position of mobile robot can be reliably estimated and the localization precision can be effectively improved, so the effectiveness of this dead reckoning system is demonstrated. 展开更多
关键词 wheeled mobile robot dead reckoning proprioceptive sensor kinematic equations
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Research on the Structural Rigidity Characteristics of a Reconfigurable TBM Thrust Mechanism 被引量:3
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作者 Younan Xu Xinjun Liu Jiyu Xu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2019年第6期35-47,共13页
To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatic... To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatically altered during operation.Therefore,millions of configurations can be obtained,and thousands of instances of working status per configuration can be set respectively.Nonetheless,the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm.This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index.To solve this problem,we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder.Then,both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces,and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established.Next,we derive the stiffness analytical equation using Hooke’s law and the Jacobian Matrix.The proposed approach provides an effective algorithm to support structural rigidity analysis,and lays a solid theoretical foundation for calculating the performance indexes of the V-TM.We then analyze the rigidity characteristics of typical configurations under different working states,and obtain the main factors affecting structural stiffness of the V-TM.The results show the deviation degree of structural parameters in hydraulic cylinders within the same group,and the working status of propelling jacks.Finally,our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM. 展开更多
关键词 Reconfigurable TBM thrust mechanism Structural rigidity characteristics Configuration matrix Patternvector kinematic harmonizing equation Dynamic compatible equation Structural stiffness equations
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STABLE PROGRAMMED MANIFOLD SOLVER FOR VIRTUAL PROTOTYPING MOTION SIMULATION 被引量:2
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作者 TAN Jianrong WANG Zheng LIU Zhenyu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2006年第1期76-80,共5页
Based on constructing programmed constraint and constraint perturbation equation, a kinematics and dynamics numerical simulation model is established for virtual mechanism, in which the difference scheme guarantee pre... Based on constructing programmed constraint and constraint perturbation equation, a kinematics and dynamics numerical simulation model is established for virtual mechanism, in which the difference scheme guarantee precision in simulation procedure and its mtmerical solutions satisfy programmed manifold stability. A crank-piston mechanism in a car engine, a steering mechanism and a suspension mechanism are simulated in a virtual environment, then comparing the simulation results with those obtained in ADAMS under the same circumstances proved the solver valid. 展开更多
关键词 kinematics Dynamics Constraint Differential-algebraic equation
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Differential geometric modeling of guidance problem for interceptors 被引量:31
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作者 LI KeBot CHEN Lei BAI XianZong 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第9期2283-2295,共13页
It is a comparatively convenient technique to investigate the motion of a particle with the help of the differential geometry the-ory,rather than directly decomposing the motion in the Cartesian coordinates.The new mo... It is a comparatively convenient technique to investigate the motion of a particle with the help of the differential geometry the-ory,rather than directly decomposing the motion in the Cartesian coordinates.The new model of three-dimensional (3D) guidance problem for interceptors is presented in this paper,based on the classical differential geometry curve theory.Firstly,the kinematical equations of the line of sight (LOS) are gained by carefully investigating the rotation principle of LOS,the kinematic equations of LOS are established,and the concepts of curvature and torsion of LOS are proposed.Simultaneously,the new relative dynamic equations between interceptor and target are constructed.Secondly,it is found that there is an instan-taneous rotation plane of LOS (IRPL) in the space,in which two-dimensional (2D) guidance laws could be constructed to solve 3D interception guidance problems.The spatial 3D true proportional navigation (TPN) guidance law could be directly introduced in IRPL without approximation and linearization for dimension-reduced 2D TPN.In addition,the new series of augmented TPN (APN) and LOS angular acceleration guidance laws (AAG) could also be gained in IRPL.After that,the dif-ferential geometric guidance commands (DGGC) of guidance laws in IRPL are advanced,and we prove that the guidance commands in arc-length system proposed by Chiou and Kuo are just a special case of DGGC.Moreover,the performance of the original guidance laws will be reduced after the differential geometric transformation.At last,an exoatmospheric intercep-tion is taken for simulation to demonstrate the differential geometric modeling proposed in this paper. 展开更多
关键词 kinematic equations of LOS instantaneous rotation plane of LOS proportional navigation augmented trueproportional navigation LOS angular acceleration guidance law differential geometric guidance commands
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Wearable sensors for 3D upper limb motion modeling and ubiquitous estimation 被引量:5
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作者 Zhang, Zhiqiang Wong, Wai Choong Wu, Jiankang 《控制理论与应用(英文版)》 EI 2011年第1期10-17,共8页
Human motion capture technologies are widely used in interactive game and learning, animation, film special effects, health care, and navigation. Because of the agility, upper limb motion estimation is the most diffic... Human motion capture technologies are widely used in interactive game and learning, animation, film special effects, health care, and navigation. Because of the agility, upper limb motion estimation is the most difficult problem in human motion capture. Traditional methods always assume that the movements of upper arm and forearm are independent and then estimate their movements separately; therefore, the estimated motion are always with serious distortion. In this paper, we propose a novel ubiquitous upper limb motion estimation method using wearable microsensors, which concentrates on modeling the relationship of the movements between upper arm and forearm. Exploration of the skeleton structure as a link structure with 5 degrees of freedom is firstly proposed to model human upper limb motion. After that, parameters are defined according to Denavit-Hartenberg convention, forward kinematic equations of upper limb are derived, and an unscented Kalman filter is invoked to estimate the defined parameters. The experimental results have shown the feasibility and effectiveness of the proposed upper limb motion capture and analysis algorithm. 展开更多
关键词 Ubiquitous motion modeling and estimation Forward kinematic equation Wearable microsensors
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Theoretical relationships between first flush of roof runoff and influencing factors 被引量:2
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作者 Biao WANG Tian L 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第5期746-757,共12页
Considering the short length of building roofs, a theoretical analysis of the first flush of roof runoff was conducted based on the kinematic wave and pollutant erosion equations. This mathematical derivation with ana... Considering the short length of building roofs, a theoretical analysis of the first flush of roof runoff was conducted based on the kinematic wave and pollutant erosion equations. This mathematical derivation with analytical solutions predicts pollutant mass first flush (MFF), mean concentration of initial runoff (MCIF), mean concentration of roof runoff (MCRR) with diversion of initial portion and residual mass available on the bed surface (RS) after the entire runoff under the condition of con-stant excess rainfall. And the effects of the associated influencing factors (roof length, roof gradient, roof surface roughness, rainfall intensity, rainfall duration, and erosion coefficients) on them were discussed while the values of parameters referred to the previous studies. The results showed that for roofs whose length is shorter than 20 m, both the increase in roof length and roof gradient and the decrease in roof surface roughness result in larger MFF and MCIF and smaller MCRR and RS, which is beneficial to water reuse and pollution reduction. The theoretical relationship between the first flush and the influencing factors may aid the planning and design of roof in terms of rainwater utilization or diffuse pollution control. 展开更多
关键词 Roof runoff kinematic wave equation Pollutant erosion equation First flush
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Nonlinear Dust Acoustic Waves in Dissipative Space Dusty Plasmas with Superthermal Electrons and Nonextensive Ions
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作者 A.M.El-Hanbaly E.K.El-Shewy +1 位作者 M.Sallah H.F.Darweesh 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第5期606-612,共7页
The nonlinear characteristics of the dust acoustic(DA)waves are studied in a homogeneous,collisionless,unmagnetized,and dissipative dusty plasma composed of negatively charged dusty grains,superthermal electrons,and n... The nonlinear characteristics of the dust acoustic(DA)waves are studied in a homogeneous,collisionless,unmagnetized,and dissipative dusty plasma composed of negatively charged dusty grains,superthermal electrons,and nonextensive ions.Sagdeev pseudopotential technique has been employed to study the large amplitude DA waves.It(Sagdeev pseudopotential)has an evidence for the existence of compressive and rarefractive solitons.The global features of the phase portrait are investigated to understand the possible types of solutions of the Sagdeev form.On the other hand,the reductive perturbation technique has been used to study small amplitude DA waves and yields the Korteweg-de Vries-Burgers(Kd V-Burgers)equation that exhibits both soliton and shock waves.The behavior of the obtained results of both large and small amplitude is investigated graphically in terms of the plasma parameters like dust kinematic viscosity,superthermal and nonextensive parameters. 展开更多
关键词 Sagdeev pseudopotential KdV-Burgers equation soliton and shock waves reductive perturbation dust kinematic viscosity
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