Compliant continuum gripper powered by dielectric elastomers based on anisotropic bending stiffness caused by integrated textile materials

Abstract

Electroactive polymers (EAP) and their related dielectric elastomers (DE) belong to a very performant and emerging class of functional materials. While being compliant and light-weight, they can be utilized to serve as integrated actuators for soft robotics. By combining EAP with the well-developed class of textile materials and their excellent capability to directly manipulate the local mechanical behavior of structures, compound materials with outstanding properties can be created. In this work a bending structure based on a fiber-elastomer compound is presented. By integrating uniaxially oriented carbon fibers under defined fiber angles in an elastomer matrix, a structure with highly anisotropic bending stiffness is achieved. By attaching dielectric layers with different pre-stretch ratios on both outer sides, an initial elastic stress state is introduced to the structure leading to an anisotropic bending deformation. An attached electrode to the outer side, together with an electrical connection of the textile layers to act as ground electrode, enables the dielectric layers to serve as driving element. Applying a voltage of up to 5000 V leads to an anisotropic bending deflection of up to 1.2 mm at the tips of the structure and 1 mm at the upper edge. Tailoring the geometrical conditions will enable the concept to serve as a gripping mechanism for arbitrarily shaped objects.