A major limitation in extrusion-based bioprinting is the lack of direct process control, which limits the accuracy and design complexity of printed constructs. The lack of direct process control results in a number of defects that can influence the functional and mechanical outcomes of the fabricated structures. The machine axes motion cannot be reliably used to predict material placement, and precise fabrication requires additional sensing of the material extrusion. We present an iteration-to-iteration process monitoring system that enables direct process control in the material deposition reference frame. To fabricate parts with low dimensional errors, we integrate a non-contact laser displacement scanner into the printing platform. After fabrication of the initial print using the as-designed reference trajectory, the laser scanner moves across the part to measure the material placement. A custom image processing algorithm compares the laser scanner data to the as-designed reference trajectory to generate an error vector. To compensate for the measured error, the algorithm modifies the axes reference trajectory for the second print iteration. We implement the in situ process monitoring and error compensation technique on an experimental platform to evaluate system performance and demonstrate improvement in spatial material placement.

中文翻译：

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基于挤出的3D生物打印中的直接过程反馈。

基于挤出的生物打印的主要限制是缺乏直接的过程控制，这限制了打印结构的准确性和设计复杂性。缺乏直接的过程控制会导致许多缺陷，这些缺陷会影响所制造结构的功能和机械结果。机器轴的运动不能可靠地用于预测材料的放置，并且精确的制造需要对材料挤压进行额外的检测。我们提出了一种迭代到迭代的过程监控系统，该系统可以在材料沉积参考系中进行直接过程控制。为了制造尺寸误差小的零件，我们将非接触式激光位移扫描仪集成到打印平台中。使用设计的参考轨迹制作完初始印刷品后，激光扫描仪在零件上移动以测量材料位置。定制图像处理算法将激光扫描仪数据与设计的参考轨迹进行比较，以生成误差向量。为了补偿所测量的误差，该算法修改了第二次打印迭代的轴参考轨迹。我们在实验平台上实施原位过程监控和误差补偿技术，以评估系统性能并展示空间材料放置方面的改进。