Journal of Guangdong University of Technology ›› 2020, Vol. 37 ›› Issue (02): 60-66.doi: 10.12052/gdutxb.190132

• Comprehensive Studies • Previous Articles     Next Articles

Removal of Redundant Constraints of Trajectory Coincidence by Substituting Lower Pair Mechanism by Higher Pair Mechanism in the Calculation of Degree of Freedom in Planar Mechanisms

Zhang Xiao-wei, Lin Xiu-jun, Zheng Ling-li, Pan Ji-sheng, Tang Wen-yan, Cheng Si-yuan   

  1. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China
  • Received:2019-10-28 Online:2020-03-10 Published:2020-01-13

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Abstract: Aiming at the redundant constraints of trajectory coincidence in the calculation of degree of freedom in planar mechanisms, substituting lower pair mechanism by higher pair mechanism method is proposed to remove them. The existence of redundant constraints of trajectory coincidence in revolute pair, prismatic pair and planar higher pair is analyzed. Taking elliptic mechanism and gear-linear mechanism as examples, the locations of redundant constraints of trajectory coincidence in mechanism pairs are analyzed, and the design of the mechanism scheme without the redundant constraints further studied. The results suggest that if there are redundant constraints of the trajectory coincidence in planar mechanism, the constraints do not exist on a fixed pair; the redundant constraint caused by adding a link with two revolute pairs at two points on two different links with fixed distance is an special case of the redundant constraints of the trajectory coincidence; without reducing the number of links, the redundant constraints of trajectory coincidence can be removed by changing the revolute pair into the planar higher pair.

Key words: planar mechanism, degree of freedom, trajectory coincidence, redundant constraint, substitution of lower pair mechanism by higher pair mechanism

CLC Number: 

  • TH112.1
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