Prs-xy Type Series-parallel Robot Global Performance Optimization Studies

The series-parallel robot (hybrid robot) which combines the advantages of both series robot and parallel robot has been applied to many fields, such as machine tool design. Based on the previous research, a new type of PRS-XY series-parallel robot is studied in terms of the kinematics, dynamics, global performance and optimization in this paper. The robot which has 5-DOF is consisted of a 3-PRS parallel mechanism and a XY table.Firstly, the characteristics of the PRS-XY series-parallel robot are analyzed in this paper, then the forward kinematics equation and inverse kinematics equation are established and the simulation software ADAMS is applied to verify equations. The workspace figures of the robot are drawn by the MATLAB software on the base of inverse kinematics, and the influence of the mechanism dimensions change on the workspace volume is discussed. Based on the kinematics analysis, the dynamics of the robot is established by using the Lagrange method. The kinematics dexterity indices, statics dexterity indices, kinematics global performance indices and statics global performance indices as well as stiffness global performance indices are presented based on the velocity Jacobian matrix, Hessian matrix, force Jacobian matrix and stiffness matrix. Then the atlases of each performance index are drawn by means of the MATLAB software, which provides the certain theoretical foundation for the optimal design and application of the robot. A multi-objective optimization function is established based on the analysis of workspace, kinematics dexterity and statics dexterity.The multi-objective optimization function which is established by weight coffeicent takes the mechanism dimension as constraints, and the workspace volume, velocity and force dexterity as the sub-objective function. Then dimension parameters of the robot are optimized by means of genetic algorithm tool in the MATLAB software, at last the optimization results are proved to be effective by comparing the results before and after optimization. Finally, in this paper the kinematics and dynamics simulation are finished by means of the ADAMS software. From the simulation curve, the kinematics regularities and force changes of the components and actuators of the robot can be intuitively observed.