Performance Analysis And Design Of A Five DOF Hybrid Manipulator

A hybrid (parallel-serial) manipulator possesses features of serial manipulators and parallelmanipulators. Thus it has highly value in engineering application. This paper focuses on theperformance analysis and design of (2-UPR-RPU)-RR hybrid manipulator. The mainachievements are as follows:The simple model of the hybrid manipulator is established. The inverse and forwardkinematic analysis of both the parallel and the serial mechanism are carried out by using theclosed-loop vector method and the D-H convention, respectively. The conclusion that a singleserial mechanism or a single parallel mechanism has the unique forward kinematic solutionwhile the parallel mechanism has at most six inverse kinematic solutions is obtained. The inverseand forward kinematics of the whole hybrid manipulator are investigated using homogeneoustransformation, and there is only one inverse kinematic solution if the rang of joint angles arelimited.The parameters of the parallel mechanism are optimized by using the force/motiontransmission performance index LTI which is based on screw theory. According to the change ofthe radius ratio ofr1andr2, the good angle area ratio is defined and the optimized radiusparameters is obtained. Then, based on the numerical search method, the reachable workspace ofthe hybrid manipulator is obtained by MATLAB, considering the constraints of actuation links,joint angles, and the interference of links.The simple3D model of hybrid machine tool is created by using SolidWorks and themethod of coordinate transformation is given. The simulation examples of single numericalsolution and spherical surface machining are proposed to verify the correctness of the inversekinematic solution of the hybrid manipulator which is deduced in this paper.The maximum milling force of hybrid machine tool is obtained through the definition andcomputing of the milling dosage. Then, the simple3D model of hybrid machine tool is importedinto ADAMS. The mass, constraints and external load are defined, and a tiny movement speed isalso added to each driving joints in order to get the force situation of hybrid machine tool underthe three typical postures. Finally, the maximum force/moment of each driving joints areintegrated.The mechanical part of hybrid machine tool, such as machine tool spindle, serial part,moving platform and branch leg are designed according to the original parameters. Some keypurchased parts, for example, motorized spindle, harmonic reducer, servo motor, ball screw,linear guide, etc, are selected. Then, the static stiffness of main structures which should meet the accuracy requirement are verified by using ANSYS. At last, the3D model of hybrid machinetool which can be used in the actual surface machining is presented.The achievements in this paper are helpful for the research and development of (2-UPR-RPU)-RR hybrid manipulator in the field of machine tool.