Soft Contact: Design and Fabrication for Gentle Grasping and Manipulation

Abstract

The compliance of soft robots makes them particularly well suited for grasping applications where target objects are fragile, compliant, or topologically complex, as well as scenarios where target objects have an uncertain size or location. This thesis is an exploration of soft robotic design and fabrication that enables three modes in which characteristics of the contact interface between soft grippers and their target objects can be strategically tuned. First, passive digit structures and materials can be used to reduce contact stress concentrations and adapt to varying object sizes. Second, active surface structures can be used to increase dexterity of soft grippers by modulating contact friction. Third, a new grasping strategy of randomly distributed contacts can be used to achieve grasps that are individually gentle and collectively strong. We call this strategy entanglement grasping and present novel manufacturing methods to create the high aspect ratio soft actuators and large arrays that are the basis for this technique. The structural compliance of high aspect ratio large collectives enable passive, stochastic adaptation to compliant target structures and complex topologies. For each modality of contact tuning, passive, active, and distributed, I present novel mechanisms, fabrication methods, and design tools to create soft grippers for gentle grasping and manipulation.