The Performance Evaluation And Dimension Synthesis Of Stephenson Fixed Cam Linkage Mechanism

Compared with the four bar linkage,the Stephenson six bar mechanism,which is born out of the Stephenson kinematic chain,can achieve more complex motion laws,motion trajectories and rigid body guidance.But it can not achieve arbitrary motion law,trajectory and rigid body guidance.As an evolutionary configuration,the Stephenson fixed cam linkage mechanism can achieve arbitrary motion rules,motion trajectories and rigid body guidance.The research and exploration of this mechanism has carried out the research and exploration of evaluation indicators / performance conditions,dimension synthesis theory and method systematically and deeply.In this paper,Stephenson fixed cam linkage mechanism is selected as the research object.Based on kinematic characteristics and structural layout,classification of mechanism types is carried out,and the shape,working principle and basic size parameters of the mechanism are analyzed.The longitudinal,transverse and overall dimensions of the mechanism are presented,and the accurate description of the synthesis problem of the mechanism size is generalized.The performance analysis and design of the mechanism must first solve the problem of the performance evaluation of the mechanism.The performance evaluation index should have clear physical meaning and computability.Six universal performance conditions/evaluation indexes are put forward,and a set of analytic formula criterion is given,which lays an important theoretical foundation for solving the problem of dimensional synthesis.In view of the Stephenson fixed cam linkage mechanism,the method of transformation mechanism is put forward,and the concept of driving and driven dimension parameters is introduced.The basic idea and steps of size synthesis,that is,the action route,sequence and mechanism of various performance evaluation indexes,have been put forward to make a scientific and reasonable path for the system to solve the problem of mechanism size synthesis.Based on the previous performance evaluation and dimension synthesis theory,a complete set of analytical formulas and criteria for evaluation index / performance conditions suitable for the programming environment are proposed by using the Visual Basic 6.0 language environment,and the performance evaluation of the Stephenson type fixed cam linkage mechanism and the software for dimension comprehensive visualization are completed.Through the deep research on the theory and method of dimension synthesis,the coupling relationship among the first/second driving size parameter and the driven size parameter is found and revealed.Combining the performance evaluation system with the size synthesis theory,a set of comprehensive,universal and effective Stephenson fixed cam linkage mechanism performance evaluation and size synthesis theory system is constructed.