Bio-inspired tactile sensor sleeve for surgical soft manipulators

Abstract

Robotic manipulators for Robot-assisted Minimally Invasive Surgery (RMIS) pass through small incisions into the patient's body and interact with soft internal organs. The performance of traditional robotic manipulators such as the da Vinci Robotic System is limited due to insufficient flexibility of the manipulator and lack of haptic feedback. Modern surgical manipulators have taken inspiration from biology e.g. snakes or the octopus. In order for such soft and flexible arms to reconfigure itself and to control its pose with respect to organs as well as to provide haptic feedback to the surgeon, tactile sensors can be integrated with the robot's flexible structure. The work presented here takes inspiration from another area of biology: cucumber tendrils have shown to be ideal tactile sensors for the plant that they are associated with providing useful environmental information during the plant's growth. Incorporating the sensing principles of cucumber tendrils, we have created miniature sensing elements that can be distributed across the surface of soft manipulators to form a sensor network capable of acquire tactile information. Each sensing element is a retractable hemispherical tactile measuring applied pressure. The actual sensing principle chosen for each tactile makes use of optic fibres that transfer light signals modulated by the applied pressure from the sensing element to the proximal end of the robot arm. In this paper, we describe the design and structure of the sensor system, the results of an analysis using Finite Element Modeling in ABAQUS as well as sensor calibration and experimental results. Due to the simple structure of the proposed tactile sensor element, it is miniaturisable and suitable for MIS. An important contribution of this work is that the developed sensor system can be "loosely" integrated with a soft arm effectively operating independently of the arm and without affecting the arm's motion during bending or elongation.

Soft Robotics：Structure, Actuation, Sensing and Control

“…。将光导纤维嵌入机器人本体，利用内部光强 的变化检测机器人的触觉 [76] 或者变形 [77][78] 。将导电 材料缠绕在弹性内核上制成可延展导电线，嵌入到 气动三维软体臂测量各腔道的长度和弯曲变化 [79] 。 智能材料在外界物理场的作用下可以变形，而利用 其变形时产生的电压等信号也可以作为传感器来使 用。如利用 SMA 制作的人工肌肉具有自感知能 力 [80] ，利用介电弹性体变形时电容的变化来检测压 力 [81] ，将 IPMC 作为传感器用于水下航行器 [82] [85] ；用系统 辨识的方法可建立输入气压和构型空间参数的关 系 [86] 。 但是 PCC 模型只适用于固定曲率的运动学求 解，对于变曲率的软体机器人运动学问题，需要尝 试新的方法，如将软体连续臂分为多段，每段近似 曲率恒定 [87][88] 。对于流体驱动弹性体和纤维增强制 动器等超弹性材料软体机器人，因其本构关系比较 复杂，学者们多采用有限元分析来研究几何参数对 运动学的影响 [89][90] 。从变形前后的几何关系来分析 其变形机理 [7] SFAKIOTAKIS M，KAZAKIDI A，TSAKIRIS D P.…”

Anchoring like octopus: biologically inspired soft artificial sucker

“…In another effort a thin layer of silicone with a hole at the centre was sandwiched between two sheets of Electrolycra and integrated underneath an artificial sucker to measure compressive tactile forces [29]. In this paper, we leverage the previous work on stiffness gradient [30][31] design of octopus suckers [25] and integrate it with a single sensory unit which can seamlessly measure both tactile and proximity information.…”

“…Biomimetic aspects of octopus suckers have been long studied; the morphology and physiology of octopus suckers and possibilities for biomimetic replication of suckers have been investigated [12,16,[21][22][23][24][25], with particular emphasis on the transition from hard to soft in the mechanical stiffness of sucker [21][22][23][24][25], also referred as stiffness gradient 2 design in some relevant literature [30][31].…”

A Multi-Modal Sensing Glove for Human Manual-Interaction Studies

“…However, this method is prone to ghosting and mirroring (detecting spurious tactile locations). Optical sensors, exploiting intensity modulation based on reflection [28] or strain in optical fibers [29], require cumbersome wiring to/from light sources and thus are too bulky for unobtrusive usage. Very high spatial resolution was achieved with a sprayed-on silicone elastomer [30], but this method was restricted to single-time usage.…”