• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2019, Vol. 55 ›› Issue (9): 18-28.doi: 10.3901/JME.2019.09.018

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Synthesis Method for Path Generation of a Planar Four-bar Mechanism Based on the Wavelet Feature Parameters

LIU Wenrui1, SUN Jianwei1,2, CHU Jinkui3   

  1. 1. School of Mechatronic Engineering, Changchun University of Technology, Changchun 130012;
    2. Key Laboratory for Terrain-machine Bionics Engineering, Jilin University, Changchun 130022;
    3. School of Mechanical Engineering, Dalian University of Technology, Dalian 116024
  • Received:2018-08-22 Revised:2018-12-08 Online:2019-05-05 Published:2019-05-05

Abstract: Wavelet function can extract the feature information of function curve in different scales. Based on the wavelet transform theory, a coupler curve generated by planar four-bar mechanism is decomposed to wavelet coefficients. A normalised process is proposed for extracting wavelet feature parameters. Then a description method for coupler curve of planar four-bar mechanism is established using wavelet feature parameters. The eleven dimensional open path synthesis problems are transformed to six basic dimensional types searching problems. A database is established, which contains 3 004 281 900 groups of dimensional types. The dimensional types are decomposed by using multidimensional search tree and an index keyword database is established. The leaf node which contains the desired mechanism can be obtained. A self-adaptive atlas database is established. Based on the design requirements, the desired mechanism can be obtained by comparing the similarity of wavelet feature parameters between the prescribed curve and the coupler curve in the self-adaptive atlas database. According to the internal relationship of wavelet coefficients, the actual sizes and installation positions of the desired linkage can be calculated. The arbitrary relative rotation interval open path synthesis is realized. Two examples are presented to demonstrate the effectiveness of the method proposed. Particularly, a roller feed mechanism for roller hemming is designed and manufactured to verify the validity and practicality of this method. The design results provide new ideas for the roller hemming.

Key words: multidimensional search tree, open path synthesis, planar four-bar mechanism, self-adaptive atlas database, wavelet feature parameters

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