Wearable wireless tactile display for virtual interactions with soft bodies.

We describe here a wearable, wireless, compact, and lightweight tactile display, able to mechanically stimulate the fingertip of users, so as to simulate contact with soft bodies in virtual environments. The device was based on dielectric elastomer actuators, as high-performance electromechanically active polymers. The actuator was arranged at the user's fingertip, integrated within a plastic case, which also hosted a compact high-voltage circuitry. A custom-made wireless control unit was arranged on the forearm and connected to the display via low-voltage leads. We present the structure of the device and a characterization of it, in terms of electromechanical response and stress relaxation. Furthermore, we present results of a psychophysical test aimed at assessing the ability of the system to generate different levels of force that can be perceived by users.The authors gratefully acknowledge financial support from COST – European Cooperation in Science and Technology, within the framework of “ESNAM – European Scientific Network for Artificial Muscles” (COST Action MP1003). Gabriele Frediani also acknowledges support from the European Commission, within the framework of the project “CEEDS: The Collective Experience of Empathic Data Systems” (FP7-ICT-2009.8.4, Grant 258749) and “Fondazione Cassa di Risparmio di Pisa,” within the framework of the project “POLOPTEL” (Grant 167/09

A Soft touch: wearable dielectric elastomer actuated multi-finger soft tactile displays

PhDThe haptic modality in human-computer interfaces is significantly underutilised when compared to that of vision and sound. A potential reason for this is the difficulty in turning computer-generated signals into realistic sensations of touch. Moreover, wearable solutions that can be mounted onto multiple fingertips whilst still allowing for the free dexterous movements of the user’s hand, brings an even higher level of complexity. In order to be wearable, such devices should not only be compact, lightweight and energy efficient; but also, be able to render compelling tactile sensations. Current solutions are unable to meet these criteria, typically due to the actuation mechanisms employed. Aimed at addressing these needs, this work presents research into non-vibratory multi-finger wearable tactile displays, through the use of an improved configuration of a dielectric elastomer actuator. The described displays render forces through a soft bubble-like interface worn on the fingertip. Due to the improved design, forces of up to 1N can be generated in a form factor of 20 x 12 x 23 mm, with a weight of only 6g, demonstrating a significant performance increase in force output and wearability over existing tactile rendering systems. Furthermore, it is shown how these compact wearable devices can be used in conjunction with low-cost commercial optical hand tracking sensors, to cater for simple although accurate tactile interactions within virtual environments, using affordable instrumentation. The whole system makes it possible for users to interact with virtually generated soft body objects with programmable tactile properties. Through a 15-participant study, the system has been validated for three distinct types of touch interaction, including palpation and pinching of virtual deformable objects. Through this investigation, it is believed that this approach could have a significant impact within virtual and augmented reality interaction for purposes of medical simulation, professional training and improved tactile feedback in telerobotic control systems.Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Centre EP/G03723X/

Enabling wearable soft tactile displays with dielectric elastomer actuators

PhDTouch is one of the less exploited sensory channels in human machine interactions. While the introduction of the tactile feedback would improve the user experience in several fields, such as training for medical operators, teleoperation, computer aided design and 3D model exploration, no interfaces able to mimic accurately and realistically the tactile feeling produced by the contact with a real soft object are currently available. Devices able to simulate the contact with soft bodies, such as the human organs, might improve the experience. The existing commercially available tactile displays consist of complex mechanisms that limit their portability. Moreover, no devices are able to provide tactile stimuli via a soft interface that can also modulate the contact area with the finger pad, which is required to realistically mimic the contact with soft bodies, as needed for example in systems aimed at simulating interactions with virtual biological tissues or in robot-assisted minimally invasive surgery. The aim of this thesis is to develop such a wearable tactile display based on the dielectric elastomer actuators (DEAs). DEAs are a class of materials that respond to an electric field producing a deformation. In particular, in this thesis, the tactile element consists of a so-called hydrostatically coupled dielectric elastomer actuator (HC-DEAs). HC-DEAs rely on an incompressible fluid that hydrostatically couples a DEA-based active part to a passive part interfaced to the user. The display was also tested within a closed-loop configuration consisting of a hand tracking system and a custom made virtual environment. This proof of concept system allowed for a validation of the abilities of the display. Mechanical and psychophysical tests were performed in order to assess the ability of the system to provide tactile stimuli that can be distinguished by the users. Also, the miniaturisation of the HC-DEA was investigated for applications in refreshable Braille displays or arrays of tactile elements for tactile maps

A reconfigurable tactile display based on polymer MEMS technology

This research focuses on the development of polymer microfabrication technologies for the realization of two major components of a pneumatic tactile display: a microactuator array and a complementary microvalve (control) array. The concept, fabrication, and characterization of a kinematically-stabilized polymeric microbubble actuator (¡°endoskeletal microbubble actuator¡±) were presented. A systematic design and modeling procedure was carried out to generate an optimized geometry of the corrugated diaphragm to satisfy membrane deflection, force, and stability requirements set forth by the tactile display goals. A refreshable Braille cell as a tactile display prototype has been developed based on a 2x3 endoskeletal microbubble array and an array of commercial valves. The prototype can provide both a static display (which meets the displacement and force requirement of a Braille display) and vibratory tactile sensations. Along with the above capabilities, the device was designed to meet the criteria of lightness and compactness to permit portable operation. The design is scalable with respect to the number of tactile actuators while still being simple to fabricate. In order to further reduce the size and cost of the tactile display, a microvalve array can be integrated into the tactile display system to control the pneumatic fluid that actuates the microbubble actuator. A piezoelectrically-driven and hydraulically-amplified polymer microvalve has been designed, fabricated, and tested. An incompressible elastomer was used as a solid hydraulic medium to convert the small axial displacement of a piezoelectric actuator into a large valve head stroke while maintaining a large blocking force. The function of the microvalve as an on-off switch for a pneumatic microbubble tactile actuator was demonstrated. To further reduce the cost of the microvalve, a laterally-stacked multilayer PZT actuator has been fabricated using diced PZT multilayer, high aspect ratio SU-8 photolithography, and molding of electrically conductive polymer composite electrodes.Ph.D.Committee Chair: Allen,Mark; Committee Member: Bucknall,David; Committee Member: Book,Wayne; Committee Member: Griffin,Anselm; Committee Member: Yao,Donggan

Soft manipulators and grippers: A review

Soft robotics is a growing area of research which utilizes the compliance and adaptability of soft structures to develop highly adaptive robotics for soft interactions. One area in which soft robotics has the ability to make significant impact is in the development of soft grippers and manipulators. With an increased requirement for automation, robotics systems are required to perform task in unstructured and not well defined environments; conditions which conventional rigid robotics are not best suited. This requires a paradigm shift in the methods and materials used to develop robots such that they can adapt to and work safely in human environments. One solution to this is soft robotics, which enables soft interactions with the surroundings while maintaining the ability to apply significant force. This review paper assesses the current materials and methods, actuation methods and sensors which are used in the development of soft manipulators. The achievements and shortcomings of recent technology in these key areas are evaluated, and this paper concludes with a discussion on the potential impacts of soft manipulators on industry and society

Development of a Tactile Thimble for Augmented and Virtual Reality Applications

The technologies that have gained a renewed interest during the recent years are Virtual Reality (VR) and Augmented Reality (AR), as they become more accessible and affordable for mass-production. The input device which allows us to interact with the virtual environment is a very crucial aspect. One of the main barriers to immerse ourselves in virtual reality is the lack of realistic feedback. The user has to almost rely entirely on visual feedback without any haptic feedback, and this increases the user's workload and decreases the performance. In this thesis, a functional demonstrator of a tactile feedback device which conveys compelling interactions with not just VR, but also AR is presented. The device is designed such that there is realistic feedback for virtual touches and least obstruction during contact of a real object in AR applications. New design principle of introducing small actuators allows the device to be compact and increases its portability. In contrast to actuators that are placed on the finger pad in most of the available input devices for VR, a tactile device with two actuators that are arranged laterally on the finger, so that the underside of the fingertip is free is proposed. The output from these actuators generate a tactile stimulus by stimulating a sense of touch, which helps the user to manipulate virtual objects. The actuators are designed to independently generate vibrations and this coupled tactile feedback enhances the stimulation resulting in a wide variety of stimulation patterns for the sense of touch. Preliminary experimental evaluation for design and location of actuators has been carried out to measure the vibration intensity. In addition, user experiments for design evaluation of the two actuators based on different vibration patterns have also been conducted