Encircling Skin Structure for Covering the Palmar and Dorsal Side of Robot Hand Joints with Thick 3-Axis Tactile Sensors

Tactile sensing is crucial for robot fingers to achieve dexterous manipulation tasks. A wide coverage with tactile sensors increases the adaptability of the hand for various tasks. However, covering certain parts of the hand such as the joints with sensors is challenging. This can cause undetected contact with the object. This paper presents a novel structure to cover a robot finger with thick tactile sensor skin. By encircling the joint and finger phalanges with the skin, the robot finger can have a vast sensing area on both the palmar and dorsal side of the finger, including the joints at the same time. Adaptive joints were implemented into the joints so that the robot finger can conform to various object shapes, which expands the contact areas for more stability. uSkin tactile sensors, which are distributed 3-axis tactile sensors for flat and curved surfaces, are implemented for evaluation. To validate the proposed structure, we confirmed that continuous tactile sensing on both sides of each joint is possible. The proposed finger also stopped its motion when touching an obstacle while the finger held an object. Finally, this paper also shows that tactile sensing on the palmar and dorsal sides can be useful to improve manipulation stability.