Towards holonomic electro-elastomer actuators with six degrees of freedom

Functionally efficient six degrees of freedom (DOF) actuators have not yet been developed in a scale-invariant and inherently compliant unified form. This has primarily been due to the use of conventional serial or parallel kinema°tical configurations and electro-magnetic motors, pneumatics and hydraulics. Contrary to traditional technologies, utilizing electro-active elastomers enables multi-DOF actuation and holonomic operation with minimal structural complexity. Conical dielectric elastomer actuators (DEAs) are compact multi-DOF actuator-sensors that are scalable and can be entirely polymeric, making them suitable for a variety of applications including minimally invasive medical devices. In this paper, cone DEAs are developed towards integrated 6-DOF actuation with muscle-like performance from a single structure. This is achieved by demonstrating the feasibility of holonomic 6-DOF actuation and through experimental characterization a 5-DOF prototype. The 5-DOF prototype (50 mm length, 60 mm diameter) produced rotational actuation outputs of ±21.7 degrees and ±9.42 mNm and linear actuation outputs of ±4.45 mm (±9.1%) and ±0.55 N. Finally, combined multi-DOF actuation is demonstrated as part of development towards scalable holonomic electro-active elastomer actuators.