| The parallel mechanism has many excellent features that have been used in the areas of aeronautical simulators,docking,vibration isolation,medical,machine tools,position adjustment,measuring machines and other applications.Four or five degrees of freedom symmetry parallel mechanism research started late,lack of configuration,engineering practice is still not wide enough.In this paper,3-CRCR/RPU symmetric four-degree-of-freedom parallel mechanism is used as the research object,and its kinematics,dynamics and its application in curtain wall installation are studied.This paper studies the structural form of the parallel mechanism and its type synthesis.The structure of the symmetric four-degree-of-freedom parallel mechanism and its constrained screw synthesis method are analyzed.A new 3-CRCR/RPU symmetric 4-DOF parallel mechanism is proposed.The modified form of Kutzbach-Grubler and the screw theory are used to analyze the motion and freedom of the mechanism.The kinematics positive and negative solutions of parallel mechanism are solved based on screw theory.The Jacobian matrix and the Hessian matrix are derived.The mechanism has no singularity and partially decoupled by analyzing Jacobian matrix.The kinematic position,velocity and acceleration of the mechanism are simulated numerically.The workspace of the mechanism is solved according to the constraint of joint space.The local and global performance indexes of the mechanism are established,which is studied for the influence of the structural parameters on the performance of the mechanism.The velocity mapping matrix between each component and the driving branch is deduced.The equivalent driving force of each part is solved by the velocity mapping matrix,and the inverse kinematics model is established based on the principle of virtual work.Finally,the application of 3-CRCR/RPU mechanism in curtain wall installation is studied.The structure of the hybrid curtain wall installation robot is designed,and the kinematic model of the hybrid robot is solved.The optimal trajectory planning of the fifth-order polynomial motion is established for the mechanism.The optimal time planning is carried out for the fifth order polynomial trajectory in the workspace of the mechanism.The gravity compensation model of the hybrid mechanism is established.A force/position hybrid control strategy based on gravity compensation is proposed.The fuzzy PID controller is designed by using Simulink module in MATLAB,and the robot structure model is introduced into ADAMS software.The multi-input and multi-output mechanical system model is established.The joint control simulation is realized by MATLAB and ADMAS software,and the expected control effect is achieved. |
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