RoTip: A Finger-Shaped Tactile Sensor with Active Rotation Capability

TL;DR

RoTip addresses the need for dynamic tactile sensing by combining full-surface contact perception with active body rotation in a finger-shaped sensor. RoTip's modular design integrates fixed attachment, rotational transmission from $0^\\circ$ to $360^\\circ$ with a $5:3$ gear ratio, and a configurable finger tip to enable reconfigurable tactile surfaces. Experimental results show manipulation of both rigid objects and thin fabrics, including spinning a hex key and rolling fabric corners to achieve a grasp, validating dexterous in-hand capabilities. This approach expands tactile manipulation possibilities by providing active rotation and complete tactile feedback for more complex tasks in contact-rich manipulation scenarios.

Abstract

In recent years, advancements in optical tactile sensor technology have primarily centred on enhancing sensing precision and expanding the range of sensing modalities. To meet the requirements for more skilful manipulation, there should be a movement towards making tactile sensors more dynamic. In this paper, we introduce RoTip, a novel vision-based tactile sensor that is uniquely designed with an independently controlled joint and the capability to sense contact over its entire surface. The rotational capability of the sensor is particularly crucial for manipulating everyday objects, especially thin and flexible ones, as it enables the sensor to mobilize while in contact with the object's surface. The manipulation experiments demonstrate the ability of our proposed RoTip to manipulate rigid and flexible objects, and the full-finger tactile feedback and active rotation capabilities have the potential to explore more complex and precise manipulation tasks.

Figures (4)

• Figure 1: From Left to Right:(a) Design overview of the RoTip sensor, and the exploded view of RoTip's three modules, i.e., (b) Fixing module, (c) transmission module and (d) Finger body. The fixing module is used to connect and provide support to other components of this sensor. The transmission module is used to drive the rotation action enabling dynamic movement. The finger body is the touch interface providing the tactile sensing capability.
• Figure 2: (a) and (b) represent RoTip sensor with a hemisphere tip and a flat tip, respectively. The first two rows display, from left to right, the transparent support shells, the coated elastomer, and the tactile images. Sparking points are noticeable due to the intense reflection from the flat tip. (c) displays the tactile readings captured as the hemisphere-tipped RoTip sensor interacts with a bolt, a nut, and a USB cable.
• Figure 3: Snapshots of manipulating rigid objects (hex key and oyster card).
• Figure 4: Snapshots of grasping four different fabrics.