Performance Analysis And Dimension Optimization Of The Tripod Parallel Robot

On the demand of automatic production in the development of medical treatment,diet,and consumer demand,the 3-PUU robot has been developed based on the traditional Delta robot,of which the parallel mechanism that is driven by the parallel way and has the characteristics of large load capacity,strong stiffness and large precision is composed of a fixed platform,a moving platform,connecting rods and translational drive parts.The Tripod parallel robot is taken as the research object,about which the dimension parameters are designed and optimized.Some theories are studied deeply which include the design and optimization of the dynamic performance index,the performance index,the kinematics workspace dexterity index and stiffness performance index,the dynamic performance index,and the global performance index.The specific contents of this paper include:(1)To build the kinematics and dynamics model.This section simplified and set up the model and DOF of the tripod robot.By using the vector method,the inverse kinematics of the 3-PUU parallel robot is obtained.Then the velocity model,the acceleration model and the rigid body inverse dynamics are all deduced.This section obtained the inverse kinematics model,velocity and acceleration model of the linear driven parallel robot based on the d’Alembert’s form of the principle of the virtual work,each actuated torque of the mechanical system moving parts are analyzed with a virtual displacement.Derived the dynamic equation and determined the affecting factors of the linear driven parallel robot.(2)To study the singular value and the working space for the 3-PUU parallel robot.The singular position and the influence factors are found and solved out for the robot.This section used the Jacobian matrix to analyze the singularity of the robot and avoid the singularity situation.This section used the numerical search method to solve the workspace of the parallel robot with the tendency of the size,shape,and symmetry of the workspace with respect to the different set of architectural parameters chosen for the manipulator.(3)According to the optimal size parameters of different performance indexes,the characteristics of high speed,high precision and high load are solved.The kinematic performance and dynamic performance of the Tripod parallel robot are listed.This section presents a new approach to the architecture optimization of the linear driving parallel robot based on the performance of a weighted sum of global dexterity index and a new performance index-space utility ratio(SUR),set up the mathematic model of parameters optimization based on the objective function of this ratio.Using particle swarm optimization to optimize the parameters of the linear driving parallel robot,obtained the optimal parameters based on the performance of the space utility index with the global dexterity index in different environment.(4)Simulation and experimental verification of the model.This section verified the forward and inverse kinematics,velocity and acceleration model through the united simulation of Matlab and Adams.Using the laser tracker to test and verified the workspace of the robot,contrast with the workspace of the polar search method in the same height of the Z plane.Contrast the load characteristic test of the electrical motor torque in the fixed track with the theoretical number to verify the correctness of the dynamics model.