A Novel Design for a Compliant Mechanism Based Variable Stiffness Grasper Through Structure Modulation
Abstract Robots utilize graspers for interacting with an environment. Conventional robot graspers are composed of rigid links and are dedicated to perform a particular task. However, such graspers have difficulty conforming to objects of varied shape and exerting varying grasping forces. Soft robotic graspers provide these features through different modalities. However, such modalities that vary the stiffness of soft robotic graspers face issues such as slow response time, requirement of external power packs for operation and low variation of stiffness. A variable stiffness compliant robotic grasper that is simple in design and operation would improve end effectors used in assistive robotics and prostheses where ability to vary stiffness would benefit in handling a wide array of objects. This research presents a novel method of achieving variable stiffness through structural transformations. Current designs utilizing structural transformations do not provide shape conformance while grasping objects. We propose a design for a soft robotic grasper utilizing the concept of stability of structures. This design is capable of adapting to the surface of an object being grasped and can rapidly vary its stiffness. The grasper behavior is modelled using Finite Element Analysis and validated experimentally. Our results demonstrate that structural transformation of flexible elements is a potential solution for achieving variable stiffness in a grasper.