During the development of this device several iterations were made in order to improve performances and reliability of the system and our final prototype comprises four pairs of opposite DEA segments moving the central part where the two cones of the structure are joined. The central part can host different devices depending on the specific application, for this proof-of-concept device we used a monochromatic laser source that can be then electrically controlled to rotate by different angles around two axis thanks to the DEAs system. The elastomer used is prestretched 3M VHB 4905 and the electrodes were made by mask-spraying a PDMS, carbon black and solvents mixture. We’re currently working at replacing the VHB acrylic elastomer with PDMS in order to further improve the reliability and the speed of the system. A big challenge was developing the driving electronics and package the whole system in a neat, safe, reliable and elegant fashion, giving the device a futuristic look and allowing for seeing the mesmerizing lifelike motion of the 8 DEAs while in operation. The control electronics includes four EMCO Q20 high voltage unit and a series of standard electronic components to successfully connect and interface them with an Arduino UNO microcontroller, which is connected via USB to a laptop where a custom-built software application is used to control the system. Two control strategies were implemented for the system: the laser pointing device can be controlled either using a two axis joystick for which we 3D printed a custom enclosure, or using a LEAP motion which allows for hand gesture control.
WIth the current design the device is capable of rotating the laser pointer in a range of 20 degrees around two perpendicular axis, allowing for a good range of movement in the space facing the device. The next steps in the development of this device could be:
replacing the laser with a video camera allowing for silently and smoothly moving it, for example to use it as a CCTV system. We’re thinking of using computer vision algorithms to use the system to move a camera around keeping a subject in the centre of the scene;
adding a camera system and implementing an eye-tracking algorithm in order to allow for pointing the laser just using the movement of the eyes. This could be very useful for people with locked-in syndromes such as ALS who could use such system to point at people or objects in their environment
References [1] HR Choi et al, Digital polymer motor for robotic applications, Robotics and Automation, 2003. Proceedings. ICRA'03 [2] Rossiter et al, Towards holonomic electro-elastomer actuators with six degrees of freedom, 2012, Smart Materials and Structures. 21 [3] Seelecke et al, Design and Control of a High-Speed Positioning System Based on Dielectric Elastomer Membrane Actuators, 2017, IEEE/ASME Transactions on Mechatronics