Inverse Position Optimization Method of Kinematically Redundant Parallel Mechanisms Based on Natural Frequency
Kinematically redundant parallel mechanisms(KR-PMs)have significant advantages in avoiding singularity,increasing workspace,improving mechanism performance and so on,but it is difficult to obtain their optimal inverse position solutions.Thus,a new inverse position optimization method of KR-PMs is proposed.Firstly,based on the closed-loop vector method and global independent generalized displacement coordinate method,the kinematic and elastodynamic models of KR-PMs are established.Secondly,the first order natural frequency(fundamental frequency)of the KR-PM is chosen as the elastodynamic performance index.For a given output pose of the moving platform,the optimal inverse position with maximum fundamental frequency is determined based on particle swarm optimization algorithm.Then,using the polynomial fitting technology,a response surface mapping between the optimal inverse position solutions and the output pose parameters of the moving platform is established,which obtains the optimal inverse position solutions of KR-PMs under different output pose parameters.Finally,the 2PUPR-PRPU KR-PM(where P denotes a prismatic joint,U denotes a universal joint,and R denotes a revolute joint)is taken as an example to implement the proposed method.The effectiveness of the method is demonstrated by comparing the fundamental frequency of the mechanism before and after optimization.
parallel mechanismkinematically redundantinverse position optimizationnatural frequency
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