Design and Control of a Multi-Modal Soft Gripper Inspired by Elephant Fingers

Soft grippers have the potential to solve many existing manipulation challenges, particularly in agile industry applications. However, existing soft grippers are often limited in the range of objects they can pick, or by cluttered environments. We present a design inspired by the nose and fingers at the end of an elephant's trunk, which can pick both by suction and pinching, allowing increased grasping diversity. In addition, we observe an emergent grasping mode, a hybrid of pinching and suction where the cup aperture is morphed online, using embedded soft fingers, to form a seal over challenging objects. An algorithmic grasping strategy, based-on analytical grasping models and primitive objects, is presented. With this, we predict grasping performance and show increased grasping range compared to other soft gripper designs. Finally, the gripper and grasping strategy are successfully applied to grasping more varied everyday objects, demonstrating exploitation of this multi-modal gripping for adaptive grasping.