Milling three-dimensional stability forecasting method of six-freedom-degree series robot

Abstract

The invention provides a milling three-dimensional stability forecasting method of a six-freedom-degree series robot and relates to the technical field of robot machining application. By means of themethod, the machining posture of the six-freedom-degree series robot is determined firstly, and the angle value of each joint of the robot is obtained; then the structural rigidity of the robot in three directions is obtained, and the milling cutting rigidity value of the robot is calculated and obtained; a homogeneous transformation matrix among all kinematics coordinate systems is obtained; theinherent frequency of various orders and corresponding modal shapes of the robot are obtained through analysis; the main rigidity direction of the robot is obtained, and the transfer matrix from cutting force to the main rigidity direction of the robot is determined; and finally, the machining direction is determined, and robot milling three-dimensional stability is used for judging and forecasting stability. By means of the milling three-dimensional stability forecasting method of the six-freedom-degree series robot, the machining feeding direction can be selected in advance, modal coupling fluttering in the milling process is avoided, and the quality of the machined surface is improved.

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.

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