Robust design and analysis of 4PUS–1RPU parallel mechanism for a 5-degree-of-freedom hybrid kinematics machine

Based on a proposed 4 degree-of-freedom (DOF) T2R2 parallel mechanism with the structural configuration of 4PUS–1RPU (4-prismatic–universal–spherical and 1-revolute–prismatic–universal), a 5-axis hybrid kinematics machine (HKM) can be developed with an additional linear motion being combined. The kinematic and dynamic performance indices for the 4-DOF parallel mechanism are developed. A novel improved RSM (response surface methodology)-based LKN (Latin hypercube design, Kriging interpolation, and neural network training) method, which is a generic robust design method for dealing with the computation-intensive engineering optimization problem, is developed in this paper. The robust design for the 4PUS–1RPU parallel mechanism by using both traditional RSM and the presented LKN method is carried out, where the first-order natural frequency is regarded as the single response objective, and the design results show that the LKN method is more effective than the traditional RSM. Based on the proposed LKN method the robust design for the 4PUS–1RPU parallel mechanism with consideration of both kinematic and dynamic performance indices is carried out. The characteristics of the robust optimal scheme are analysed in detail. The prototype of the HKM with the parameters obtained from the robust design scheme is developed, and the machining experiments show that the proposed HKM can implement the 5-axis machining with the structural and cross-sectional parameters that are much more robust and optimal.