In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the...In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.展开更多
In recent years,defunct satellites mitigation in the geostationary orbit(GEO) has become a hot issue in the space field.How to transfer defunct geostationary satellites to the graveyard orbit safely,economically and e...In recent years,defunct satellites mitigation in the geostationary orbit(GEO) has become a hot issue in the space field.How to transfer defunct geostationary satellites to the graveyard orbit safely,economically and efficiently presents new challenges to spacecraft dynamics and control.This paper conducts an in-depth investigation on tether-tugging de-orbit issues of defunct geostationary satellites.Firstly,a four-phase tether-tugging de-orbit scheme including acceleration,equilibrium,rotation and return is proposed.This scheme takes into consideration how to avoid the risks of tether ripping,tug-target collision,and tether twist,and how to achieve the mission objective of fuel saving.Secondly,the dynamics model of the tether combination system is established based on Lagrange equation,and the four phases of tether-tugging de-orbit scheme are simulated respectively.Simulation results indicate that the scheme is theoretically feasible and satisfies the design objectives of safety,economy and efficiency,providing a technical approach for engineering application.展开更多
A consistent focus in theoretical mechanics has been on how to apply Lagrange's equation to continuum mechanics.This paper uses the concept of a variational derivative and its laws of operation to investigate the ...A consistent focus in theoretical mechanics has been on how to apply Lagrange's equation to continuum mechanics.This paper uses the concept of a variational derivative and its laws of operation to investigate the derivation of Lagrange's equation,which is then applied to nonlinear elasto-dynamics.In accordance with the work-energy principle and the energy conservation law,kinetic and potential energies are proposed for rigid-elastic coupling dynamics,whose governing equation is established by manipulating Lagrange's equation.In addition,case studies are used to demonstrate the application of the proposed method to spacecraft dynamics.展开更多
A geometric setting for generally nonconservative mechanical systems on fibred manifolds is proposed. Emphasis is put on an explicit formulation of nonholonomic mechanics when an unconstrained Lagrangian system moves ...A geometric setting for generally nonconservative mechanical systems on fibred manifolds is proposed. Emphasis is put on an explicit formulation of nonholonomic mechanics when an unconstrained Lagrangian system moves in a generally non-potential force field depending on time, positions and velocities, and the constraints are nonholonomic, not necessarily linear in velocities. Equations of motion, and the corresponding Harniltonian equations in intrinsic form are given. Regularity conditions are found and a nonholonomic Legendre transformation is proposed, leading to a canonical form of the nonholonomic Hamiltonian equations for nonconservative systems.展开更多
基金Project(2006AA04Z405) supported by the National High Technology Research and Development Program of ChinaProject(3102019) supported by Beijing Municipal Natural Science Foundation,China
文摘In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.
基金supported by the National Hi-Tech Research and Development Program of China ("863" Project) (Grant No. 2011AA7044026)
文摘In recent years,defunct satellites mitigation in the geostationary orbit(GEO) has become a hot issue in the space field.How to transfer defunct geostationary satellites to the graveyard orbit safely,economically and efficiently presents new challenges to spacecraft dynamics and control.This paper conducts an in-depth investigation on tether-tugging de-orbit issues of defunct geostationary satellites.Firstly,a four-phase tether-tugging de-orbit scheme including acceleration,equilibrium,rotation and return is proposed.This scheme takes into consideration how to avoid the risks of tether ripping,tug-target collision,and tether twist,and how to achieve the mission objective of fuel saving.Secondly,the dynamics model of the tether combination system is established based on Lagrange equation,and the four phases of tether-tugging de-orbit scheme are simulated respectively.Simulation results indicate that the scheme is theoretically feasible and satisfies the design objectives of safety,economy and efficiency,providing a technical approach for engineering application.
基金supported by the National Natural Science Foundation of China(Grant No.10272034)
文摘A consistent focus in theoretical mechanics has been on how to apply Lagrange's equation to continuum mechanics.This paper uses the concept of a variational derivative and its laws of operation to investigate the derivation of Lagrange's equation,which is then applied to nonlinear elasto-dynamics.In accordance with the work-energy principle and the energy conservation law,kinetic and potential energies are proposed for rigid-elastic coupling dynamics,whose governing equation is established by manipulating Lagrange's equation.In addition,case studies are used to demonstrate the application of the proposed method to spacecraft dynamics.
基金supported by the Czech Science Foundation (Grant No.GA CˇR 201/09/0981)the Czech-Hungarian Cooperation Programme "Kontakt" (Grant No. MEB041005)the IRSES project ’GEOMECH’ (Grant No. 246981) within the 7th European Community Framework Programme
文摘A geometric setting for generally nonconservative mechanical systems on fibred manifolds is proposed. Emphasis is put on an explicit formulation of nonholonomic mechanics when an unconstrained Lagrangian system moves in a generally non-potential force field depending on time, positions and velocities, and the constraints are nonholonomic, not necessarily linear in velocities. Equations of motion, and the corresponding Harniltonian equations in intrinsic form are given. Regularity conditions are found and a nonholonomic Legendre transformation is proposed, leading to a canonical form of the nonholonomic Hamiltonian equations for nonconservative systems.
