Chitalia Yash, Deaton Nancy Joanna, Jeong Seokhwan, Rahman Nahian, Desai Jaydev P
Medical Robotics and Automation (RoboMed) Laboratory, Georgia Center for Medical Robotics (GCMR), Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
IEEE Robot Autom Lett. 2020 Apr;5(2):1712-1719. doi: 10.1109/lra.2020.2969934. Epub 2020 Jan 28.
Endovascular and endoscopic surgical procedures require micro-scale and meso-scale continuum robotic tools to navigate complex anatomical structures. In numerous studies, fiber Bragg grating (FBG) based shape sensing has been used for measuring the deflection of continuum robots on larger scales, but has proved to be a challenge for micro-scale and meso-scale robots with large deflections. In this paper, we have developed a sensor by mounting an FBG fiber within a micromachined nitinol tube whose neutral axis is shifted to one side due to the machining. This shifting of the neutral axis allows the FBG core to experience compressive strain when the tube bends. The fabrication method of the sensor has been explicitly detailed and the sensor has been tested with two tendon-driven micro-scale and meso-scale continuum robots with outer diameters of 0.41 mm and 1.93 mm respectively. The compact sensor allows repeatable and reliable estimates of the shape of both scales of robots with minimal hysteresis. We propose an analytical model to derive the curvature of the robot joints from FBG fiber strain and a static model that relates joint curvature to the tendon force. Finally, as proof-of-concept, we demonstrate the feasibility of our sensor assembly by combining tendon force feedback and the FBG strain feedback to generate reliable estimates of joint angles for the meso-scale robot.
血管内和内窥镜手术需要微型和中尺度的连续体机器人工具来在复杂的解剖结构中导航。在众多研究中，基于光纤布拉格光栅（FBG）的形状传感已被用于在较大尺度上测量连续体机器人的挠度，但对于具有大挠度的微型和中尺度机器人来说，这已被证明是一项挑战。在本文中，我们通过将一根FBG光纤安装在一个微加工的镍钛诺管内开发了一种传感器，该镍钛诺管由于加工原因其中性轴向一侧偏移。中性轴的这种偏移使得当管子弯曲时FBG纤芯会受到压缩应变。已详细阐述了该传感器的制造方法，并使用两个分别外径为0.41毫米和1.93毫米的肌腱驱动微型和中尺度连续体机器人对该传感器进行了测试。这种紧凑的传感器能够以最小的滞后对两种尺度的机器人形状进行可重复且可靠的估计。我们提出了一个分析模型，用于从FBG光纤应变推导出机器人关节的曲率，以及一个将关节曲率与肌腱力相关联的静态模型。最后，作为概念验证，我们通过结合肌腱力反馈和FBG应变反馈来生成中尺度机器人关节角度的可靠估计，展示了我们传感器组件的可行性。
