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soft boundaries, weights and elastic behaviour. When operating robots, the scaling of movement and forces can be tuned arbitrarily in software. In the case of robotic surgery, appropriate software can filter out tremors and breathing movements for added precision. In academia, new shapes and implementations crop up, such as the adaptive interface presented by researchers of the Kyung Hee University (Korea). By controlling the size of a movable silicone balloon (inflated through a pneumatic actuator in accordance with the size of a virtual object being touched) and with finger video tracking, the researchers recreate the sensation of a real interaction with soft round-shaped objects. (a) Kyung Hee University’s pneumatic haptic interface; (b-d) the size of the balloon is adjusted to fit the contact area; (e-g) the user can grasp the interface and move the hand to feel the variations in size. The balloon is mounted on a position-controlled robotic arm so as to adapt its position to follows the user’s hand and get in contact only when the both the hand and the object are making contact in the virtual world. This system could be used to interact with a human avatar, or to palpate virtual organs, say for medical training purposes. The solution unveiled by researchers of the University of Leuven (Belgium) in their paper “Towards Palpation in Virtual Reality by an Encountered-type Haptic Screen” is somewhat a hybrid approach between a screen and the encountered-type interface described earlier. Eurohaptics 2014 To summarize it simply, the joystick is replaced with a robotarm mounted screen featuring a tensioned polyethylene sheet in front of the user for adequate compliance. Markers both on the user’s index and on the screen’s frame, allow a camera to precisely track the index’ position relative to the screen. Not only the screen follows the index position, but the tracking system also computes how much stiffness there ought to be in the interfacing sheet when the user comes into contact and moves over or inside the surface, to match the impedance of the soft virtual object being touched. Other virtual 3D manipulation haptic interfaces can take the shape of multiple finger straps tied to various strings whose tension is precisely controlled by motors. Such arrangements, dubbed SPIDAR (Space Interface Device for Artificial Reality) by researchers from the Tokyo Institute of Technology, can be rather complex but can offer full digit operation, as demonstrated with their SPIDAR-10. The wire-driven multi-finger haptic interface can render a 3 degree-of-freedom spatial force feedback on all ten fingers through 4 wires attached to each fingertip. For the unconstrained manipulation of virtual objects, with both hands, rotary frames support the string actuators that allow users to twist their hands (say to solve a virtual Rubik’s cube), rotating with the user’s hands to reduce the interference of the wires. To round up this report, I would like to highlight two startups freshly setup. Spun-out from the Institut des Systèmes Intelligents A wire-driven multi-finger haptic interface with spatial feedback. et de Robotique (ISIR) in Paris and co-founded by professor Vincent Hayward, General Chair of the EuroHaptics 2014 conference, Actronika was demonstrating haptic effects based on a seemingly simple idea, the use of recorded sounds through a vibrotactile transducer to add the haptic effect corresponding to what would offer the real world experience. In one demonstration, you were holding a chopstick fitted with a Haptuator (a high-bandwidth 9x9x32mm vibro-tactile transducer from Canadian company TactileLabs) while looking at a video of a stylus pushing its way through a box full of marbles. By driving the Haptuator with the original audio recordings of the video, just like a common loudspeaker but only with acceleration outputs, pushing the vibro-tactile chopstick on a flat screen gave the exact sensation of pushing it through colliding marbles. Large VR object palpation through a encountering display: concept and flow chart (University of Leuven). Actronika’s Haptuator Mark II demonstration on a chop stick. 12 Electronic Engineering Times Europe July/August 2014 www.electronics-eetimes.com


EETE JULAUG 2014
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