Gomes Daniel Fernandes, Lin Zhonglin, Luo Shan
smARTLab, Department of Computer Science, niversity of Liverpool, Liverpool, United Kingdom.
School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China.
Front Robot AI. 2020 Nov 19;7:541661. doi: 10.3389/frobt.2020.541661. eCollection 2020.
Tactile sensing is an essential capability for a robot to perform manipulation tasks in cluttered environments. While larger areas can be assessed instantly with cameras, Lidars, and other remote sensors, tactile sensors can reduce their measurement uncertainties and gain information of the physical interactions between the objects and the robot end-effector that is not accessible via remote sensors. In this paper, we introduce the novel tactile sensor that has the shape of a finger and can sense contacts on any location of its surface. This contrasts to other camera-based tactile sensors that either only have a flat sensing surface, or a compliant tip of a limited sensing area, and our proposed GelTip sensor is able to detect contacts from all the directions, like a human finger. The sensor uses a camera located at its base to track the deformations of the opaque elastomer that covers its hollow, rigid, and transparent body. Because of this design, a gripper equipped with GelTip sensors is capable of simultaneously monitoring contacts happening inside and outside its grasp closure. Our extensive experiments show that the GelTip sensor can effectively localize these contacts at different locations of the finger body, with a small localization error of approximately 5 mm on average, and under 1 mm in the best cases. Furthermore, our experiments in a Blocks World environment demonstrate the advantages, and possibly a necessity, of leveraging all-around touch sensing in manipulation tasks. In particular, the experiments show that the contacts at different moments of the reach-to-grasp movements can be sensed using our novel GelTip sensor.
触觉感知是机器人在杂乱环境中执行操作任务的一项基本能力。虽然利用摄像头、激光雷达和其他远程传感器可以立即评估较大的区域，但触觉传感器可以减少其测量不确定性，并获取通过远程传感器无法获得的物体与机器人末端执行器之间物理交互的信息。在本文中，我们介绍了一种新型触觉传感器，它具有手指形状，能够感知其表面任何位置的接触。这与其他基于摄像头的触觉传感器形成对比，其他此类传感器要么只有一个平坦的传感表面，要么有一个传感面积有限的柔性尖端，而我们提出的凝胶指尖（GelTip）传感器能够像人类手指一样从各个方向检测接触。该传感器使用位于其基部的摄像头来跟踪覆盖其空心、刚性和透明主体的不透明弹性体的变形。由于这种设计，配备凝胶指尖传感器的夹具能够同时监测其抓握闭合内部和外部发生的接触。我们广泛的实验表明，凝胶指尖传感器能够有效地将这些接触定位在手指主体的不同位置，平均定位误差约为5毫米，在最佳情况下误差小于1毫米。此外，我们在积木世界环境中的实验证明了在操作任务中利用全方位触摸感知的优势，甚至可能是必要性。特别是，实验表明，使用我们的新型凝胶指尖传感器可以感知到达抓取动作不同时刻的接触。
