Because of industrial robots’ relatively low stiffness, many research efforts have been performed to improve the robot stiffness by optimizing the robot posture. For freeform surfaces with large curvature, however, the expected high stiffness posture may undergo excessive changes that exceed the robot joint speed limit. Therefore, the stiffness optimization may not achieve the expected results in actual machining owing to the limitation of robot kinematics and conventional toolpath pattern. To address this problem, a region-based toolpath generation method is proposed to improve robot stiffness in this study for robotic milling of freeform surfaces. To provide the possibility of higher stiffness robot posture, not only the redundant degree of freedom (DOF) of the robot but also the orientation of tool axis during machining is optimized. Under the influence of surface curvature and position, the change of high stiffness posture has regionality. A surface subdivision method is proposed to divide the surface into multiple sub-regions, so that actual robot posture with better stiffness can be obtained. For each sub-region, the feed direction of toolpath is optimized to further enhance robot stiffness. Simulations and experimental studies are conducted, and show that the proposed toolpath generation method can improve the robot stiffness in freeform surface machining.

由于工业机器人的刚度较低，因此已经进行了许多研究工作，以通过优化机器人姿态来提高机器人刚度。但是，对于具有大曲率的自由曲面，预期的高刚度姿势可能会发生超出机器人关节速度极限的过度变化。因此，由于机器人运动学和常规刀具路径模式的限制，刚度优化可能无法在实际加工中获得预期的结果。为了解决这个问题，在本研究中，针对自由曲面的机器人铣削，提出了一种基于区域的刀具路径生成方法，以提高机器人的刚度。为了提供更高的机器人姿势刚度，不仅优化了机器人的冗余自由度（DOF），而且优化了加工过程中刀具轴的方向。在表面曲率和位置的影响下，高刚度姿态的变化具有区域性。提出了一种表面细分方法，将表面划分为多个子区域，从而可以获得具有更好刚度的实际机器人姿态。对于每个子区域，优化刀具路径的进给方向，以进一步提高机器人的刚度。进行了仿真和实验研究，结果表明所提出的刀具路径生成方法可以提高自由曲面加工中的机器人刚度。优化了刀具路径的进给方向，以进一步提高机器人的刚度。进行了仿真和实验研究，结果表明所提出的刀具路径生成方法可以提高自由曲面加工中的机器人刚度。优化了刀具路径的进给方向，以进一步提高机器人的刚度。进行了仿真和实验研究，结果表明所提出的刀具路径生成方法可以提高自由曲面加工中的机器人刚度。