A three-dimensional stability prediction method for six-degree-of-freedom tandem robot milling

Abstract

The invention provides a three-dimensional stability prediction method for six-degree-of-freedom serial robot milling, and relates to the technical field of robot processing applications. This method firstly determines the processing pose of the six-DOF series robot, and obtains the angle value of each joint of the robot; then obtains the structural stiffness of the robot in three directions, and calculates the milling cutting stiffness value of the robot; obtains the relationship between the kinematic coordinate systems Homogeneous transformation matrix; analyze and obtain the natural frequency of each order structure of the robot and the corresponding mode shape; obtain the main stiffness direction of the robot, and determine the transfer matrix from the cutting force to the main stiffness direction of the robot; finally determine the processing direction, and use the robot to mill the three-dimensional Stability Judgment predicts stability. The method for predicting the three-dimensional stability of the six-degree-of-freedom serial robot milling process provided by the present invention can pre-select the machining feed direction, avoid the occurrence of modal coupling chatter during the milling process, and improve the quality of the machined surface.

Description

technical field [0001] The invention relates to the technical field of robot processing applications, in particular to a three-dimensional stability prediction method for six-degree-of-freedom serial robot milling. Background technique [0002] Unlike traditional multi-axis machine tool processing, the structural rigidity of robots is weak, usually less than 1N / μm, and modal coupling chatter is extremely prone to occur. Mode coupling flutter refers to the self-excited vibration phenomenon caused by the vibration system absorbing energy from the outside due to the displacement delay feedback between various degrees of freedom (that is, between various modes). Flutter prediction currently mainly uses the BIBO stability criterion, which simplifies the robot milling process to process a two-degree-of-freedom dynamics problem in a two-dimensional plane, obtains the characteristic equation, and applies system dynamics knowledge to determine stability. The stability criterion is r...

AI Technical Summary

Problems solved by technology

The previous chatter prediction method is obtained by analyzing the milling plane, which cannot accurately define the direction of the main stiffness of the robot, which hinders the application of the criterion

[0004] Therefore, the stability prediction method for two-dimensional robot milling cannot accurately obtain the angle between the main stiffness direction and the feed direction

For this reason, the stability criterion has limitations, and there will be inaccurate identification, which makes the application and promotion of the criterion impossible to continue.

Images