Research on reliability of mode coupling chatter of orthopedic surgery robot

In this paper, the reliability probability method is introduced into the prediction of mode coupling chatter of the orthopedic surgical robot milling to avoid the influence of the randomness of the input parameters on the chatter prediction results. The reliability of mode coupling chatter is defined to represent the probability of the stability (no mode coupling chatter occurs) of milling system. Probability model (reliability model) of mode coupling chatter is established to predict robotic milling chatter, in which the modal stiffness K _x , K _y and cutting force coefficient K_s involved in the prediction of chatter vibration during robotic milling are considered as random variables. The fourth moment method is adopted to solve the reliability model of milling system to obtain the reliability level. The mode coupling chatter reliability circle diagram (MCCRCD), which is a contour line with a specified reliability level as a function of the angle between the main stiffness direction and the cutting force and the depth of cut, is presented to identify the mode coupling chatter reliable and unreliable regions. An example studies the influence of random variables on the reliability of milling processing, and the time-domain simulation method and experiment method are used to verify the possibility and effectiveness of using MCCRCD to predict the stability of the robotic milling. It can be concluded that MCCRCD can be effectively used to predict the stability of robotic milling.