Robotic curved layer additive manufacturing (a.k.a. multi-axis 3D printing) has been gaining attention recently owing to its simplicity and unique ability of printing complex shapes without using a support structure. However, as the printing path now is no long planar and the nozzle orientation is no longer fixed but changes continuously during printing, even though it could be smooth when defined in the workpiece coordinate system in both position and orientation of the nozzle, due to the inevitable numerical errors, it typically is unsmooth with many sharp-changing undulations when transformed to the coordinate system of the robot arm. As a result, the feed rate of printing has to be set extremely conservatively lest the printer would chatter or vibrate and seriously jeopardize the printing quality. In this paper, first, we present a practical B-spline based smoothing algorithm for removing sharp corners on the printing path while upholding the required cusp-height threshold on the printed surface. Next, for the smoothed printing path, we propose a feed rate scheduling strategy that will try to maximize the variable feed rate while subject to the kinematic constraints of the six joints of the robot arm. Both computer simulations and physical printing experiments are carried out to assess the proposed methodologies and the results give a positive confirmation on their advantages.

机器人曲面层增材制造（又名多轴3D打印）近来由于其简单性和无需使用支撑结构即可打印复杂形状的独特能力而备受关注。但是，由于现在的打印路径不再是平坦的，并且喷嘴方向不再固定，而是在打印过程中连续变化，尽管由于在工件坐标系中在喷嘴的位置和方向上定义时它可能是平滑的，不可避免的数值误差，当转换为机械臂的坐标系时，通常会有许多急剧变化的起伏不平滑。结果，必须非常保守地设置打印的进给速度，以免打印机抖动或振动，并严重损害打印质量。在本文中，首先，我们提出了一种实用的基于B样条的平滑算法，用于消除打印路径上的尖角，同时保持打印表面上所需的牙尖高度阈值。接下来，对于平滑的打印路径，我们提出一种进给速度调度策略，该策略将尝试在机械臂的六个关节受到运动学约束的同时最大化可变进给速度。进行计算机模拟和物理印刷实验以评估所提出的方法，结果对其优点给予了肯定的肯定。我们提出了一种进给速度调度策略，该策略将在机器人手臂的六个关节受到运动学约束的情况下，尝试最大程度地提高可变进给速度。进行计算机模拟和物理印刷实验以评估所提出的方法，结果对其优点给予了肯定的肯定。我们提出了一种进给速度调度策略，该策略将在机器人手臂的六个关节受到运动学约束的情况下，尝试最大化可变进给速度。进行计算机模拟和物理印刷实验以评估所提出的方法，结果对其优点给予了肯定的肯定。