Design And Theory Research On Reconfigurable Deployable Polyhedral Mechanism

Deployable mechanism is widely used in daily necessities,adaptive structures and large deployable equipments due to its good foldable and deployable performances.With the fast rhythm of city life and development of aerospace technology,deployable mechanism encounters new opportunities and challenges.It becomes a frontier issue to increase deploying and manipulating modes and meet different task requirements without changing assembly configuration.In this thesis,a series of reconfigurable units based by half platforms,angulated elements,straight elements and parallelogram mechanisms are designed by the means of merging platforms,making axes of revolute joints collinear and self-crossing.Reconfigurable deployable polyhedral mechanisms(RDPM)derived from Platonic polyhedra,semi-regular polyhedra,Johnson polyhedra and duoprism are built by inserting the reconfigurable units into the vertices,faces and bodies of corresponding polyhedra.A systematic design theory and method of RDPMs is obtained.The researches mainly contain:(1)Based on the reconfigurable property of angulated elements,reconfigurable angulated element(RAE)with four half-platforms is designed and analyzed.A class of reconfigurable deployable Platonic mechanisms is constructed by inserting RAEs into the vertices and adjacent faces of Platonic polyhedra.Two kinds of reconfigurable generalised angulated elements(RGAE)comprised of two GAEs(n-SEs-2-RGAEs and n-AEs-2-RGAEs)are investigated.The kinematics of n-AEs-2-RGAEs in two motion modes is emphasized,the size parameters of angulated elements and platforms are identified to make the mechanism reach its fully-retracted state and fully-expanded state.Reconfigurable deployable Platonic mechanisms with large magnification ratio are further constructed based on 1-AEs-2-RGAEs,and the calculation method of their magnification ratios in different motion modes is also detailed.(2)The differences of semi-regular polyhedra and Platonic polyhedra are analyzed.The mobile conditions for merging two pairs of angulated elements are investigated,and reconfigurable double pairs of angulated elements(RDAE)are constructed.Parameter constraints of angulated elements and platforms are detailed and the kinematics of RDAE in two motion modes is analyzed.Reconfigurable deployable triangular prismatic mechanism is constructed by inserting RDAE into the vertices and adjacent faces of triangular prism.Reconfigurable triple pairs of angulated elements(RTAE)are also constructed by merging three pairs of angulated elements.Reconfigurable deployable J3 mechanism is finally constructed by inserting RDAE and RTAE into two kinds of vertices and their adjacent faces of J3.(3)Based on whole platforms,half platforms and straight elements,three kinds of reconfigurable units(reconfigurable straight elements(RSE),reconfigurable double pairs of straight elements(RDSE),reconfigurable triple pairs of straight elements(RTSE))are designed.The independent variables among parameter variables of elements and platforms are determined.Degenerated reconfigurable deployable tetrahedral,triangular prismatic,C60 and J3 mechanisms are constructed by inserting these kinds of reconfigurable units into the corresponding polyhedra.The kinematics of RDSE is also analyzed and the distances between platform centers and body center of degenerated reconfigurable deployable triangular prismatic mechanism are illustrated correspondingly.(4)Three kinds of extended parallelogram mechanism(EPaM)are constructed based on straight elements and angulated elements.The detailed parameters and motion modes of these EPaMs are analyzed and the magnification ratios of these EPaMs in different motion modes are further calculated.Triangular,pentagonal and hexagonal reconfigurable face units are constructed by arranging EPaMs circumferentially.Reconfigurable deployable hexahedral prismatic and C60 mechanisms are constructed by inserting reconfigurable face units into faces of the corresponding polyhedra and connecting these units by edge blocks.(5)Based on scalable units and revolute joints,self-crossing triangular prismatic mechanism is constructed,its three typical gaits(self-crossing gait,inchworm gait,self-crossing and inchworm gait)are investigated.Double triangular prismatic mechanism is constructed and its inchworm gait with three climbing platforms is investigated.3-3 duoprism mechanism is constructed using "Body" construction method.Eversion motion is realized by the rational motion planning of self-crossing gait sequences.The feasibility of applying the prism and duoprism mechanisms as mobile robots is verified by mobility analysis,kinematic analysis,gait analysis,dynamic simulation and prototype fabrication.To sum up,a systematic research is carried out by designing and analyzing reconfigurable units and RDPMs,and a series of RDPMs are constructed.The proposed construction method of RDPMs provides more motion modes for deployable polyhedral mechanisms and makes them more adaptive for changing environments.This research may inspire the reconfigurable design of other kinds of deployable mechanisms.