CAREER: Modular Origami in Soft Robotic Systems

Worcester Polytechnic Institute, Worcester MA

Investigators

Abstract

This Faculty Early Career Development Program (CAREER) project studies new ways to engineer specified mechanical properties into soft robots. Soft robots are intelligent machines with a highly compliant physical structure -- that is, the body of the soft robot will bend when relatively small forces are applied to it. High compliance makes soft robots much safer around people than traditional rigid robots, and also allows soft robots to attain a variety of shapes and to move in many more ways than robots with only a small number of discrete joints. Because structures that are easy to bend cannot carry large loads, a major challenge in soft robotics is to create variable-stiffness structures that are compliant only in certain directions, or only at specific times. This project presents a new approach to engineering variable-stiffness soft robots, inspired by the art and science of "origami," or paper folding. Origami-inspired soft robots use thin sheets of relatively stiff materials that are made bendable along designated fold lines; the folding pattern can be used to create very precise and complex equivalent mechanical properties. This engineered flexibility contrasts with soft robot structures made of materials such as rubbers and foams, which are limited in their achievable strength by the intrinsic softness of the material itself. In this project, origami-inspired folding patterns are used to create modules with a specified compliant behavior. Larger and more capable robots can then be built up by combining many such modules. Examples of the potential of modular origami-inspired robots include soft tentacle-like manipulation in confined spaces, whole-body and passive conformal grasping, and controllable shape change. The results of the project will advance the national health and prosperity, by enabling origami-inspired soft robots to be used in homes, hospitals, and manufacturing sites, as care-givers, co-workers, and self-morphing structures. Educational activities integrated with this project will use origami-inspired robots as teaching tools for students of all ages through outreach activities, high-school internships, and undergraduate projects. This project will establish modular and scalable design and fabrication methods, characterize and model mechanical properties, and test control algorithms for lightweight origami-inspired modular continuum soft robots to intelligently perform manipulation, grasping, and shape-change tasks. A comprehensive integrated research and education plan will address (1) modular origami design, fabrication, and modeling, to study the mapping between mechanical properties of origami-inspired modules and their design/fabrication parameters, electrically addressable actuation using distributed tendons, distributed soft sensing of 3-D deformation and external forces, and computationally efficient clothoid formulation of continuum section deformations under external loads for dynamic modeling; (2) Control methods that endow soft robots with intelligence, to enable safe force/position interaction with the environment, synergistically combining motion planning and control at the state space, and hyper-redundancy of large scale modular systems to morph into desired shapes with minimal actuation and sensing requirements. Results will be evaluated through validation case studies in continuum arm manipulation, whole-body wrapping and utilizing conformal contact for grasping, and shape change and stiffness control by very large degree-of-freedom origami actuation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.