Design And Research On Polyhedron Ground Mobile Linkage With Planarity Constructing

With the expansion of the human activities and exploration areas,the research on ground mobile robots with more machine flexibility and adaptability has gradually become a hot topic.In a view of mechanism,this thesis will try to improve its mobility and obstacle crossing ability through the flexibility and large deformation ability of linkage mechanism,and then achieve the purpose of enhancing its envirornmental adaptability.In this thesis,based on the idea of polyhedron mobile linkage mechanism with planarity constructing,two kinds of configuration construction methods are systematically proposed,including the construction method of spatial-crossed polyhedral mechanisms and the construction method of circular-array polyhedral mechanisms.In the construction method,the evolutionary process in the construction method forms regular and serialized configurations,and the variation process deduces randomly new configurations with different deformation modes.For the configurations mentioned in this thesis,the degree of freedoms(DOFs)of mechanism,driving configuration method,kinematics,mobile feasibility,simulation and prototype experiments will be studied and analyzed.The researches mainly contain:(1)Based on the general idea of planarization construction of polyhedron mechanisms,two methods of configuration construction are put forward through the analysis of typical planar mechanism.The first one is the construction method of spatial-crossed polyhedral mechanisms,that is,the plane mechanism is orthogonal in space with its central symmetry line as its axis.The second one is the construction method of circular-array polyhedral mechanisms,which is the polyhedron mechanism formed by several planar mechanisms connected in series through the edges.(2)According to the evolutionary process of the construction method of spatial-crossed polyhedral mechanisms,three spatial-crossed parallelograms rolling mechanism is proposed.By orthogonalizing three parallelograms,the mechanism can obtain good stiffness and turning flexibility.Geometric analysis method is used in the analysis process.The mechanism is simplified by the specific geometric relations which are ubiquitous in the polyhedron,and the kinematics analysis process is effectively simplified.(3)According to the variation process in the construction method of spatial-crossed polyhedral mechanisms,the cross plane linkage of three spatial-crossed parallelograms rolling mechanism is transformed into well-shaped mesh,and a novel rhombohedron rolling mechanism is proposed.Because the variation process destroys the upper and lower platforms of the original mechanism,the rhombohedron mechanism achieves completely centrosymmetrical characteristics,which makes the mechanism have more flexible mobility.(4)The configurations formed by the construction method of spatial-crossed polyhedral mechanisms restrict the movement of the mechanism to a certain extent due to the whole closed-loop structure.In order to break this restriction,this thesis try to make the mechanism more flexible by lifting the part plane restriction of the polyhedron.Based on this idea,a novel four circular-array contra-parallelograms rolling mechanism is proposed.This configuration has planar and spherical motion modes,and has more extensive space for movement and more abundant deformation capacity.(5)On this basis,the construction method of circular-array polyhedral mechanisms is summarized and refined.By combining four typical planar linkage mechanisms with four series arrangement forms,16 configurations are proposed.Through the analysis of its movement function and operation function,it is concluded that this kind of mechanism has strong deformability,including but not limited to going straight,going oblique,variable step size,investigation concealment,climbing slope,height limited,etc.The gaits in different environments are explained in detail.(6)For the circular-array polyhedral mechanisms,a set of DOF calculation methods and driving configuration methods are proposed.The assembly deduction method is introduced through planar mechanism,and the calculation formula for the DOF is given.The idea is to subtract the constraints of assembly process from the DOFs of the mechanism in series,so as to obtain the overall DOFs of the mechanism.Because of the large number of DOFs of this kind of mechanisms,the method of driving configuration for this kind of mechanisms is put forward,and the reasonable installation position of driving motor is given.Through the above analysis,it can be concluded that the spatial-crossed polyhedral mechanisms has good stiffness,and the circular-array polyhedral mechanisms has prominent deformation ability.The construction method of the polyhedron mechanism proposed in this thesis provides an important reference value for the ground mobile polyhedron mechanisms.Geometric analysis method,DOF analysis method and drive configuration method will also provide theoretical basis for the analysis of polyhedron mechanisms.