Elastic Cube Actuator with Six Degrees of Freedom Output

Abstract

Unlike conventional rigid actuators, soft robotic technologies possess inherent compliance, so they can stretch and twist along every axis without the need for articulated joints. This compliance is exploited here using dielectric elastomer membranes to develop a novel six degrees of freedom (6-DOF) polymer actuator that unifies ordinarily separate components into a simple cubic structure. This cube actuator design incorporates elastic dielectric elastomer membranes on four faces which are coupled by a cross-shaped end effector. The inherent elasticity of each membrane greatly reduces kinematic constraint and enables a 6-DOF actuation output to be produced via the end effector. An electro-mechanical model of the cube actuator is presented that captures the non-linear hyperelastic behaviour of the active membranes. It is demonstrated that the model accurately predicts actuator displacement and blocking moment for a range of input voltages. Experimental testing of a prototype 60 mm device demonstrates 6-DOF operation. The prototype produces maximum linear and rotational displacements of ±2.6 mm (±4.3%) and ±4.8° respectively and a maximum blocking moment of ±76 mNm. The capacity for full 6-DOF actuation from a compact, readily scalable and easily fabricated polymeric package enables implementation in a range of mechatronics and robotics applications.

Multi-directional crawling robot with soft actuators and electroadhesive grippers

“…A simplified model is proposed in this work to quantify the stroke and blocking force relationship of the disk DEA. The approach is similar to that in [19]. Due to the symmetry of this DEA design, we only analyze the actuation in one direction.…”

Towards efficient elastic actuation in bio-inspired robotics using dielectric elastomer artificial muscles

“…In addition, compact multi-degree-of-freedom (DOF) actuators that mimic the antagonistic muscle groups can be achieved using DEAs. For example, the spring roll design with two-DOF [8], a five-DOF cone DEA [9,10], and a six-DOF elastic cube actuator [11]. Other advantages of DEAs over conventional actuators include high energy density, scalability and low cost [12].…”

Design of dielectric elastomer actuators using topology optimization on electrodes

“…Anderson et al [25] designed a dexterous motor where six divided electrode sectors on the DE were charged in sequence to produce rotary motion. Wang et al [26] proposed a cube actuator which can obtain 6-DOF motions through applying voltage on different electrode quadrants. Zou et al [27] investigated the active shape control of a membrane DEA by applying air pressure and voltage where the control strategy was affected by the electrode patterns.…”