Design and fabrication of a soft-bodied gripper with integrated curvature sensors

Abstract

This paper presents the design and fabrication process of a soft-bodied gripper with integrated curvature sensors for shape control. The soft gripper contains three identical fingers based on the principle of fluid elastomer actuator. Each of the finger is made of silicon rubber, named Dragon Skin, and is connected to a robotic arm by a snap-lock mechanism. Grasping ability of the soft-bodied gripper is explored by picking up cup containers filled with beans. The optimal working pressure is 20 kPa, with which a maximum weight of 90 g beans can be picked up with 100% success rate. Although the soft gripper can fulfil the requirement of picking up the soft and deformable object, finger shape needs to be controlled during the process of moving the object. It is found that the weight distribution of the cup container filled with beans changes when the cup is moved. Finger shape is sensitive to the changing of weight distribution, leading to a fail grasping. An integrated curvature sensor based on carbon nanotubes filled composite is developed to overcome this limitation. With the integrated curvature sensor, real-time monitoring and controlling of the finger shape can be realized to achieve more accuracy grasping for fragile and delicate objects.