Posture and path optimization based on stiffness performance index in robotic milling

In recent years, industrial robots (IRs) have been widely used in the field of machining. The relatively low stiffness causes the IRs to be prone to deformation during processing and reduces the machining accuracy. According to the milling and stiffness characteristics of robots, this paper presents an optimization method for posture and path. Firstly, considering the influence of milling force and spindle gravity on the normal deformation of the machining plane, the posture stiffness performance index (PSPI) is proposed. Secondly, considering the dynamic characteristics of the machining, the machining path is discretized, and the machining path stiffness performance index (MPSPI) is proposed. Then, a machining path optimization model is established by minimizing MPSPI. Finally, the experimental results of milling are discussed to illustrate the effectiveness of the proposed indices. Analyzing the machining parameters based on PSPI and MPSPI, it is concluded that selecting the appropriate feed direction, machining area, and redundancy angles can improve machining accuracy.