Type Synthesis Of Spatial Multi-loop Coupling Mechanisms Without Parasitic Motion

Spatial coupling mechanism is a new type of mechanism.It not only presents the complex multi ring mesh geometry,and the movement of the branches is no longer relatively independent.Each branch is shown as an interrelated coupling motion.At present,the spatial coupling mechanism has been widely used in people’s production and life.Such as robot,astronomical telescope,large construction machinery and other fields can see the coupling mechanism.However,the type synthesis of coupling mechanism is still at the primary stage,lacking of systematic and deep research.So it is an important and urgent task to study the type synthesis of spatial coupling mechanism.The main content of this paper is to type synthesis of two-layer and two-loop spatial mechanisms without parasitic motion based on screw theory.The main research work is as follows:Based on the screw theory,this paper aims to propose a general method for synthesizing a class of two-layer and two-loop spatial mechanisms utilizing their mutual restrain relations,and the procedure for synthesizing two-layer and two-loop mechanisms is proposed.Combining with the type synthesis method of graphical approach,using the geometry relations between constraint force/constraint force couple and the continuous rotation axes of mechanism,the two-layer and two-loop spatial mechanisms of two,three,four,and five degrees of freedom without parasitic motion are synthesized,and a series of two-layer and two-loop spatial mechanisms without parasitic motion are enumerated.One of the mechanisms is selected to verify the efficiency and correctness of the method.The type synthesis method of two-layer and two-loop spatial mechanisms proposed in this work,taking advantage of the mutual restrain relations between the branches of coupling mechanisms,combining with the type synthesis method of graphical approach,could not only avoid the travails of screw computations,but also take comprehensive situations into account.It has unique advantages of efficient,simple,and geometrically intuitive.