On A Novel 6-DOF Compliant Parallel Manipulator

With the increasing demand for micromanipulation,the inherent precision defects of conventional rigid parallel mechanisms are increasingly prominent.The compliant mechanism has the characteristics of integral molding,assembly-free,lubrication-free,miniaturization,high precision,etc.The compliant mechanism can realize the movement of micron or even nano-level accuracy,and is widely used in MEMS,precision manufacturing,micro-positioning devices,astronomical equipment,micro processing and assembly of electromechanical products and biomedical fields.The purpose of this thesis is to design a novel compliant parallel mechanism with six degrees of freedom,and to analyze and study its kinematics performance based on the theory of compliant mechanism.Based on the 6-UPS parallel mechanism and the characteristics of the right circular cross-section compliant spherical joint,this thesis proposes a force-inversion spatial structure layout,and designs a new six-degree-of-freedom compliant parallel mechanism that can withstand large loads.Firstly,based on the study of the typical compliant spherical joint freedom and compliance matrix,the compliance matrix of the right circular cross-section compliant spherical joint is established.The compliance matrix of the single branch of the force-inversion structure branch based on right circular cross-section compliant spherical joint is derived by matrix transformation.And then,the overall compliance matrix the compliant parallel mechanism is obtained.Secondly,the comparative analysis of the displacement of the numerical method and the finite element method under the same load conditions to verify the correctness of the compliance matrix.At the same time,the finite element analysis is used to illustrate the characteristics of the mechanism that can withstand large loads.The natural frequency and modes of the compliant parallel mechanism are studied by the modal analysis module in the finite element method.Furthermore,the generalized eigenvalue decomposition of the compliance matrix of the compliant parallel mechanism is performed,and the generalized eigenvalues and eigenvectors of the compliance matrix are solved.The number and properties of the degrees of freedom of the mechanism are numerically analyzed by the symbolic formulation and verified by screw theory.Finally,the right circular cross-section compliant spherical joint workspace obtained by the boundary search method and the actuating unit stroke are used as constraints,the Monte Carlo method is used to solve the workspace of the mechanism and represent it visually through the scatter plot.