Research On Dynamics And Simulation Of Double Flexible Manipulators Of The Space Station

With the development of science and technology, the pace of space explorationcontinuously push forward, space science and technology will affect humandevelopment. According to the three-step strategy of China’s manned space program,China will build its own space station in2020.Manipulator participation in the formation process of the space station andmaintenance process, Manipulator was needed in the formation process of the spacestation, to grab the module of the axial interface and transfer it to other interface, toprepare for the next rendezvous and docking. Space station maintenance need theastronaut launch a space with Manipulator, or direct repair by a manipulator equippedwith a dexterous hand. To achieve the above functions, the manipulator’s length is about10meters, but because of the high launch costs, manipulator’s quality was limited, sothe space station manipulator should be deal with as a flexible body.Aiming at time-varying dynamical systems like orbit space manipulator, because ofits floating base, time-varying centroid, large load and rigid-flexible coupling caused alot of trouble in dynamic analysis. This article used the finite element method (FEM) todiscrete flexible manipulator, in the base of considering the orbital velocity andacceleration, as well as system eccentric, with absolute angular velocities as statevariables, the General dynamics formula of N-order space manipulator was established.In the basis of the previous section, dynamics model of the space station wasestablished; and in accordance with the general structure of the space station, Andaccording to the space station’s structure, the transfer process was planned. For thespace station dynamic model, the article innovative discussed the symmetry of massmatrix, symmetric or not is concerned with generalized displacements selected forrotation equation.Due to the finite element method was used to discrete flexible body, the dimensionof the system was higher than other method. In order to get the numerical solution of theequation, the constrained mode and unconstrained mode are two ways to expand theequation and dimensionality reduction. For the system mentioned in the paper wastime-varying dynamic system, so calculate process need to repeatedly solve thevibration frequency and the formation of the system, in order to get an accurate solutionfor fast computation, using the dynamic segmentation method by the size of the jointangle, to ensure the calculation accuracy at the same time greatly improved the speed ofthe running program.Through compare flexible system with rigid system results under the samesimulation conditions, draw a conclusion that the movement trends of the two cases wasthe same, which from the side proved the reliability of the dynamics. By comparing a segmented unconstrained mode with the usual constrained mode program results, thearticle proved that using reasonable segmentation angle (0.1°) has little effect on thesimulation; through comparing different dimensionality reduction programs, came to aconclusion that a reliable result can obtained using the first six modes. In the last, giventhe specific translocation process simulation results, the individual angular velocity,elastic body vibration, the system eccentricity and Euler angle changes of the transferprocess.