Kinematics And Error Analysis Of A Redundant Metamorphic Parallel Mechanism

With the deepening of the research on space parallel mechanism,new functional requirements have been put forward and new models of various parallel mechanisms are emerging.In order to adapt to more application scenarios,the emergence of metamorphic and redundant theory has provided new design ideas for more complex institutions and has gradually become a research hotspot.In this thesis,the 3-PUPS mechanism is designed based on the principle of metamorphic redundancy in the traditional 3-UPS parallel mechanism.3 driving and moving pairs are added at the connection of the fixed platform to make the fixed platform variable,and the whole mechanism realizes the metamorphic and redundant driving.By analyzing the kinematic characteristics of the mechanism,the position inverse solution and velocity mapping relationship under redundant actuation mode are obtained,and the velocity Jacobi matrix under full redundancy driving is derived.Numerical examples verify the correctness of the inverse position solution and velocity model.Based on the kinematic model,the 3-PUPS parallel mechanism is modeled by error theory,and the error theoretical model with all the main error sources is established and the Jacobian error matrix is derived.The relationship between error source and output error is analyzed,the measurement error model is established,and a numerical example is analyzed with MATLAB.The influence of the length error of the driving rod on the output error is obtained.The correctness of the measurement model is verified,and the main factors affecting the terminal output error are analyzed.The composition and working principle of the prototype are introduced.By setting up the joint experimental platform of ABB robot and HALCON machine vision software,the length of each main moving driving pair is measured,and the error of the 3-PUPS parallel mechanism prototype is verified.The experimental results show that the difference between the measured value and the theoretical value of the protocol driving chain is within a reasonable range.The redundant actuated parallel mechanism achieves the accuracy requirements,and this error analysis method and experimental means have certain application value.