Dynamic Modeling And Optimization Of A Large Deployable Ring Structure Consisting Of V-fold Bars And Scissors Mechanism

Due to the rapid increase of information transference volume, satellite, as animportant repeater station, urgently need to carry antennas of larger radius. However,the volume and weight capacity of launch rocket is limited, which demands the spacelarge antennas able to be folded while launching and deployed after when reaching theorbit. Such antenna is space large deployable antenna, which can be broadly applied andhave been researched by many countries. However, high demands in both design andmanufacture trap China currently in only prospective researches. Meanwhile, inprospective researches, deployment possibility and dynamic modeling with responseanalysis have always been of vital importance and much difficulty. Therefore, thisarticle presents a conceptual design of a novel large deployable mechanism, establish itsdynamic model and optimize it.Firstly, a novel close loop single mobility basic deployable unit, consisting apair of V-fold bars and scissors mechanism, is presented. This mechanism can copewith extreme thermal effects, for it consists of a pair of V-fold bars. The scissorsmechanism increases the stiffness while replaced the sliding pair with revolute joints,which largely reduced the manufacture and maintenance difficulty. Based on thisscheme of basic deployment unit, kinematic model has been established, degree offreedom as well as singularity has been analyzed and ways of mobile assembly of theunit has been illustrated.Next, based on the basic analysis of the mechanism, both rigid and flexiblemulti-body dynamic model has been built to research the mechanism's deploymentdynamics. Since the mechanism consists of more than one closed loop, the dynamicmodeling would be rather difficult. However, the author used Kane equation for rigidmulti-body dynamic modeling, which avoids the inner force of the mechanism. Throughthe rigid dynamic model, given the input rod's motion, driving force at each momentcan be calculated, based on which can the deployment process be controlled. Indeformable multi-body system dynamic modeling, floating frame of referenceformulation has been used. Given the driving force, through the deformable dynamicmodel, displacement, velocity and acceleration of the mechanism's endpoint at eachtime point can be obtained, which clearly reveals the vibration and trembling of themechanism when driven by force. These results provide crucial guiding significance tothe design of the mechanism. Meanwhile, it can serve further researches into nonlinearfactors such as thermal effect, joint clearance and such.Finally, the author researches into the ring structure's static and dynamic stiffnessproperties in its fully deployed state by building its finite element model, for theydirectly decide the antenna's precision, stability and reliability. Based on all the previousstudies, through comprehending diverse factors such as performances in various aspects, budget and such, an optimization of the entire ring structure has been made with a set ofoptimal design parameters obtained. Moreover, according to all the research work above,some design rules and experiences were drawn.