Abstract: In order to solve the problems of the difficulty of determining the principal stiffness directions of industrial robots due to asymmetric structures and mode coupling chatters occurred in robotic milling processes caused by poor rigidity, a stiffness orientation method was proposed.Moreover, the stability of milling processes was improved by controlling the robot functional redundancy and optimizing the posture. Firstly, the stiffness ellipsoid in Cartesian coordinate system at the end of industrial robots was calculated to determine robotic principal stiffness directions in the cutting planes. Then, the stability criterion of mode coupling chatters was obtained by establishing the dynamics model of the machining system. Further, based on the stiffness orientation method, a posture optimization algorithm was proposed for robotic milling. Cutting experiments confirm that stability in robotic milling along the given trajectory may be guaranteed through the optimization of industrial robot configurations without changing other parameters.

Key words: robotic milling, mode coupling chatter, stiffness orientation, posture optimization

摘要： 针对工业机器人结构非对称引起的主刚度方向难以确定、因刚度低导致的铣削过程中容易发生模态耦合颤振的问题，提出了一种机器人加工系统主刚度定向方法，并利用机器人功能冗余特性优化姿态，以提高铣削过程的稳定性。计算工业机器人末端笛卡儿坐标系中的刚度椭球，确定切削平面内机器人的主刚度方向；通过建立加工系统的动力学模型，得到机器人铣削模态耦合颤振的稳定性判据；基于刚度定向方法，提出一种机器人铣削姿态优化算法。实验结果表明，在不改变其他参数的情况下，通过优化工业机器人姿态，可以保证机器人沿给定轨迹加工的稳定性。

关键词: 机器人铣削, 模态耦合颤振, 刚度定向, 姿态优化