Optimization Design And Research Of A 5-DOF Series-parallel Robot

Compared with the series robot,the series-parallel robot has better rigidity and higher precision.And it has larger workspace and higher modularity compared with the parallel robot.The series-parallel robot has gradually gained a better competitive advantage in mechanical processing by virtue of these characteristics.At present,it has been used in aerospace parts processing,automobile engine processing and other fields.This paper aims at designing a 5-DOF series-parallel robot.And the research on kinematics analysis,error analysis,optimization design of structural parameters and finite element analysis of key components is carried out.First of all,based on the topological structure and theoretical structure model,the number and nature of the DOF of the series-parallel robot are analyzed by screw theory and the modified formula of DOF.The kinematic analysis of the parallel structure and the whole structure of the series-parallel robot are carried out through the methods of intermediate parameters and equivalent joint respectively.Based on the kinematic model,the Jacobian matrix of this series-parallel robot is dimensionally unified,which lays the foundation for the subsequent kinematic performance indexes.Then based on the configuration and basic kinematics model,the sensitivity and influence rule of structural parameters and end pose errors are analyzed by the error model.And the key structural parameters with high sensitivity and their initial ranges are obtained.It benefits further structural parameter optimization design of series-parallel robot and initial design of the robot.In order to realize the optimization design,five important performance objectives from three aspects of kinematics,stiffness and motion range are carried out.The indexes includes the comprehensive index of kinematic performance based on condition number,the indexes of maximum and minimum stiffness at the end of parallel structure based on modified stiffness matrix,and the indexes of motion ranges based on the bounding theory along two axes.Considering the actual installation,motion and load limits,numerical reliability,several constraints are constructed.Then the intelligent optimization algorithm is used to solve the multi-objective optimization problem.On the basis of the result,by analyzing the correlations between the structural parameters and the objective functions,some guidance for design and simplification can be obtained.Finally,after applying the external load at the end of the robot,the data obtained from the load transfer simulation is used to carry out the finite element simulation analysis of the key components.The stress and strain of key components are analyzed and checked to ensure the strength of the robot.Based on this,the design and manufacture of the series-parallel robot prototype is completed.