Ito Takatoshi, Fukuchi Eri, Tanaka Kenta, Nishiyama Yuki, Watanabe Naoto, Fuchiwaki Ohmi
Department of Mechanical Engineering, Yokohama National University, Yokohama 240-8501, Japan.
Micromachines (Basel). 2022 Aug 7;13(8):1270. doi: 10.3390/mi13081270.
In this paper, we describe a newly developed vision feedback method for improving the placement accuracy and success rate of a single nozzle capillary force gripper. The capillary force gripper was developed for the pick-and-place of mm-sized objects. The gripper picks up an object by contacting the top surface of the object with a droplet formed on its nozzle and places the object by contacting the bottom surface of the object with a droplet previously applied to the place surface. To improve the placement accuracy, we developed a vision feedback system combined with two cameras. First, a side camera was installed to capture images of the object and nozzle from the side. Second, from the captured images, the contour of the pre-applied droplet for placement and the contour of the object picked up by the nozzle were detected. Lastly, from the detected contours, the distance between the top surface of the droplet for object release and the bottom surface of the object was measured to determine the appropriate amount of nozzle descent. Through the experiments, we verified that the size matching effect worked reasonably well; the average placement error minimizes when the size of the cross-section of the objects is closer to that of the nozzle. We attributed this result to the self-alignment effect. We also confirmed that we could control the attitude of the object when we matched the shape of the nozzle to that of the sample. These results support the feasibility of the developed vision feedback system, which uses the capillary force gripper for heterogeneous and complex-shaped micro-objects in flexible electronics, micro-electro-mechanical systems (MEMS), soft robotics, soft matter, and biomedical fields.
在本文中，我们描述了一种新开发的视觉反馈方法，用于提高单喷嘴毛细管力夹持器的放置精度和成功率。毛细管力夹持器是为毫米级物体的拾取和放置而开发的。该夹持器通过其喷嘴上形成的液滴与物体的顶面接触来拾取物体，并通过先前施加在放置表面上的液滴与物体的底面接触来放置物体。为了提高放置精度，我们开发了一种结合两个摄像头的视觉反馈系统。首先，安装一个侧面摄像头从侧面捕捉物体和喷嘴的图像。其次，从捕获的图像中，检测用于放置的预施加液滴的轮廓和被喷嘴拾取的物体的轮廓。最后，根据检测到的轮廓，测量用于释放物体的液滴顶面与物体底面之间的距离，以确定喷嘴下降的合适量。通过实验，我们验证了尺寸匹配效果相当良好；当物体横截面的尺寸更接近喷嘴的尺寸时，平均放置误差最小。我们将这一结果归因于自对准效应。我们还证实，当喷嘴形状与样品形状匹配时，我们可以控制物体的姿态。这些结果支持了所开发的视觉反馈系统的可行性，该系统在柔性电子、微机电系统（MEMS）、软机器人技术、软物质和生物医学领域中使用毛细管力夹持器来处理异质且形状复杂的微物体。
