Flexible dielectric elastomer components to revolutionise soft robots
Heavy rigid components including engines, gearboxes and rigid linkages usually make up traditional robots. These components allow them to carry out complex movements and processes but, in most cases, render them unable to perform movements that mimic biological models. DEAs changing the game The ANSWER project, coordinated by TU Dresden set out to change this. “Our aim is to integrate sensing, signal processing and actuation using only flexible DEAs in soft robotic structures without conventional electronics,” outlines Professor Gerald Gerlach, project coordinator and a Marie Curie fellow. DEAs allow flexible mechanisms to behave like artificial muscles. They usually consist of mechanically pre-strained elastomer membranes and compliant electrodes. As they are lightweight, they can produce impressive muscle-like strains. While controlling DEAs is complex, expensive and requires external electronic control units, “they can also act as sensors and piezoresistive switches (dielectric elastomer switches - DESs), enabling the integration of monitoring and control functions in compliant components themselves,” stresses Professor Gerlach. Moving towards an autonomous soft robot without electronics “The main outcome of the project is that we have demonstrated a wide variety of DE-based electronic components and active structures, controlled by them,” points out Professor Gerlach. To achieve this, the first stage of the project saw to the development of basic concepts of soft, biomimetic DE robot design and functional sub-units. Furthermore, the team derived analytically and numerically the mechanical modes of the elastomer materials used, and developed a working finite element model that was validated experimentally. The first electronic free semi-soft robot, known as Trevor the Caterpillar, and a study for a dragonfly wing, known as Jule Dragonfly, was developed, assembled and tested. In Dresden, the development of soft robotics continued and resulted in several functional demonstrators. Manufacturing technologies such as ink-jet printing, injection moulding and aerosol deposition have been investigated and used to produce soft robotic demonstrators. Overcoming obstacles The transfer from homemade DE structures to ink jet ones was a challenging task for ANSWER. To deal with this obstacle and to foster a greater understanding of ink properties, “the project introduced bridge technologies, such as aerosol deposition of different inks that have been used to produce and demonstrate various DE-driven robotic structures and signal processing components,” outlines Professor Gerlach. By exploiting the know-how generated during this development, ANSWER was able to ink jet print functional DEAs and DESs and are now working on further demonstrators. The next steps Professor Gerlach highlights: “The project will lead to the world’s first totally compliant biomimetic DE robot without conventional electronics.” This robot will only require a direct current supply voltage to fulfill biomimetic, predicted tasks and smartly interact with its environment. Additionally, the results and the generated know-how of ANSWER are currently being used in several research projects at TU Dresden and will be used in future collaborative research projects between this university and the University of Auckland. ANSWER plans to commercialise some of the results within a start-up company. To do this, funding opportunities are currently being investigated.
Keywords
ANSWER, soft robot, dielectric elastomer actuator (DEA), conventional electronics, biomimetic, dielectric elastomer switches (DESs), aerosol deposition, ink jet printing
