Vibration error-based trajectory planning of a 5-dof hybrid machine tool

Abstract

This paper presents an approach for the trajectory planning of a hybrid machine tool based on vibration error, which aims at determining the optimal location and machining time of a given machining path. Firstly, an elastodynamic model of the hybrid robot is proposed by taking compliance of joints and limbs into account. Then, in order to evaluate vibration error in a typical machining path, two indices, i.e., the mean value and fluctuation of vibration error throughout the whole trajectory are proposed. Based on the Isight platform, sensitivity analysis is conducted. In addition, optimal trajectories are derived when adopting 3–4–5 polynomial and B-splines, respectively. Results show that the machining time and machining angle have important impacts on the mean value and fluctuation of vibration error. Especially, effects of the machining angle on the vibration error cannot be neglected. Comparison shows that adopting B-splines is conductive to decreasing the required torque and power. This paper provides a method on determining optimal machining location quickly for a given path throughout the whole workspace. The proposed method can be applied to trajectory planning of other hybrid robots or parallel kinematic machines.