Shape and Tactile Perceptions of Soft Fingers via Distributed Curvature Sensing for Intelligent Grippers

Human fingers are one of the most remarkable organs for handling complex tasks or manipulating unknown objects, not only due to its dexterous and powerful movement capabilities but also its rich kinematic sense at joints and tactile sensing at skins. Shape and tactile sensing are crucial for soft pneumatic fingers to achieve embodied intelligence. Reliable tactile sensing of soft pneumatic-driven robots is particularly challenging due to its large deformation and adaptability. Here, we propose a distributed local curvature sensing-based solution for simultaneous shape and tactile perceptions in real-time. Utilizing 4 seamlessly integrated bidirectional bending curvature sensing units, real-time shape curve, contact location, and contact force can be obtained. Experimental results indicate a maximum shape reconstruction error of 0.3 mm (when the reconstruction length is 90 mm) and a force estimation error of 0.02 N (RMSE, range 0-0.4 N). Moreover, a two-finger gripper was developed; shape and tactile sensing during grasping of diverse objects (varies in weight, size, stiffness) and force-controlled grasping are achieved. Utilizing the shape-sensing and contact-event detection capabilities, dimension of the grasped objects can be recognized in real-time. This work provides an effective, highly robust, easy-to-implement, and transformative perception solution for soft bionic fingers and beyond.