Research On Kinematic Performance And Simulation Of 3-UPRR Parallel Mechanism

The less-degree-of-freedom parallel mechanism is an important branch of parallel mechanisms.It has the advantages of simple structure and easy to control.It can be used in medical equipment,precision machining,aerospace and other fields.This paper takes the3-UPRR parallel mechanism as the research object,the motion,kinematics,dynamics and virtual prototype simulation of the mechanism are studied.Firstly,the configuration of the 3-UPRR parallel mechanism is introduced.The degree of freedom of the mechanism is solved based on screw theory.Determined that the mechanism can achieve three dimensional translational motion.According to the principle of the organization’s active input selection,it is determined that three mobile pairs are selected as active inputs.Secondly,based on the homogeneous coordinate transformation method,the position positive solution equation and negative solution equation are established.The correctness of the position equation is verified by MATLAB software and ADAMS software.Based on the position equation,the Jacobian matrix and the Hessian matrix of the mechanism are obtained by the motion influence coefficient method.Then get the speed and acceleration expressions of the mechanism.Thirdly,through the analysis of Jacobian matrix,finds that there are three kinds of situations of the singular pose of the mechanism.In the configuration of the mechanism,the structural parameters can be adjusted to avoid the occurrence of strange poses of the mechanism.The workspace influence factors of the mechanism are analyzed.The numerical search method is used to obtain the workspace of the mechanism under the given parameters.Finally,based on the singularity and the workspace,the trajectory design of the “and”character is made.The displacement and velocity of the input drive are analyzed.The mechanism can be applied in engraving devices.Fourthly,based on virtual work principle,the static mechanism of the mechanism is analyzed,and the relationship between the external load and the drive input of the mechanism in equilibrium is obtained.The dynamics of the mechanism is analyzed by Lagrangianmethod.The dynamic equation of 3-UPRR parallel mechanism is obtained.Finally,a virtual prototype model of 3-UPRR parallel mechanism is created.The kinematics simulation analysis is performed.The displacement,velocity and acceleration curves of the drive rod and the moving platform reference point are obtained.The dynamic simulation analysis of 3-UPRR parallel mechanism is carried out.The change rule between input drive and external load is obtained to guide the selection of motor.