Soft Touch using Soft Pneumatic Actuator-Skin as a Wearable Haptic Feedback Device

Understanding the external environment depends heavily on vision, audition, and touch. Like vision and audition, the human sense of touch is complex. Tactile perception is composed of multiple fundamental and physical experiences felt as changes in stiffness, texture, shape, size, temperature, and weight by the skin. While researchers and industries have made continuous efforts to abstract and recreate these haptic experiences, haptic devices are still limited in invoking intricate and rich sensations. Herein, the design, model, and experimental validation of a wearable skin-like interface, able to recreate the roughness, shape, and size of a perceived object is presented; a platform for an interactive "physical" experience. The cogency of immersion through tactile feedback on moldable clay by the user response from the active haptic feedback, is examined. For the experimental test, a soft pneumatic actuator (SPA)-skin interface (90Hz bandwidth) with a complex actuation pattern is prototyped. The SPA-skin's performance using three sets of simulated textures (

Soft Pneumatic Actuator Skin with Piezoelectric Sensors for Vibrotactile Feedback

Jamie Paik, Harshal Arun Sonar

The latest wearable technologies demand more intuitive and sophisticated interfaces for communication, sensing, and feedback closer to the body. Evidently, such interfaces require flexibility and conformity without losing their functionality even on rigid surfaces. Although there have been various research efforts in creating tactile feedback to improve various haptic interfaces and master–slave manipulators, we are yet to see a comprehensive device that can both supply vibratory actuation and tactile sensing. This paper describes a soft pneumatic actuator (SPA)-based skin prototype that allows bidirectional tactile information transfer to facilitate simpler and responsive wearable interface. We describe the design and fabrication of a 1.4 mm-thick vibratory SPA – skin that is integrated with piezoelectric sensors. We examine in detail the mechanical performance compared to the SPA model and the sensitivity of the sensors for the application in vibrotactile feedback. Experimental findings show that this ultra-thin SPA and the unique integration process of the discrete lead zirconate titanate (PZT)-based piezoelectric sensors achieve high resolution of soft contact sensing as well as accurate control on vibrotactile feedback by closing the control loop.

Frontiers Media Sa2016

Application of ultrasonic motors to MR-compatible haptic interfaces

Dominique Chapuis

Functional Magnetic Resonance Imagery (fMRI) is an imaging technique allowing the observation of brain activity. Haptic interfaces can be used in conjunction with fMRI to stimulate the subject while measuring brain activity. Using robotic stimulation over conventional methods offers repeatability, flexibility and the possibility of logging of different experiment variables. Such system becomes a powerful tool for neuroscience study, diagnostic and rehabilitation. The MR scanner with its high magnetic fields and radio frequency pulses is a harsh environment for a robotic system. Robots that can operate safely and do not induce disturbances in the imaging of the scanner are qualified as MR-compatible. The actuation of these robots is an important issue. Electrical power brought to the actuator represents an important source of interferences with the scanner. Since electrical motors cannot be introduced in the MR room, haptic interfaces are conventionally remotely actuated over a long transmission with the actuators placed outside of the MR room. In particular cases, such as the study of finger motion, small haptic interfaces with limited force ranges are required. Remote actuation methods impose transmission lengths and means that cannot be reduced nor scaled down thus imposing a trade-off between performances and size reduction in these applications. This work investigates an alternative actuator that can achieve high-quality force-interactions with the fingers. The Ultrasonic Motor (USM) is MR-compatible and offers good performances. But it is not well suited for force-feedback and may be hazardous for the users. To address these issues, mechanical solutions are investigated by using an electrical analogy applied to mechanical systems. A novel actuation system using the USM as a power source and a clutch to control the output torque is proposed: the Hybrid USM Clutch Actuator (HUCA). The first prototype validates the different mechanical concepts developed in this work. The second, MR-compatible, integrates a clutch based on electrorheological fluids (ER). MR-compatibility has been validated and performances evaluated. Since the HUCA has the unique property of behaving both like a force source and a velocity source, dedicated control schemes have been developed to implement impedance and admittance force control. These enable the display of stiff walls and the rendering of a wide range of impedances thanks to the overlap of their range of displayable impedances. Compared to the hydrostatic transmission actuation, the HUCA shows higher performances and user safety. Furthermore, the powering through electrical wires allows developments of multi-DOF interfaces.

EPFL2009

Application of Tactile Perception Enhancement

Sylvain Cardin

Surrounding environment is mainly perceived through sight and hearing. Our sense of touch is mostly dedicated to explore the surface of objects using hands and fingers. Tactile sensitivity of the body skin is rather limited in common life, however this represents a viable channel to pass information. The goal of this thesis is to study the added value of tactile stimulation to increase perception in specific application contexts. First, we define our motivation and approach regarding existing tactile systems and scientific knowledge available. In order to study tactile influence in different applications, we decided to build our own hardware and software blocks based on vibrotactile actuators driven by embedded electronics communicating with an external computer. Our objective was to explore different research directions by assessing added value in term of perception for tactile stimulation. The first topic we study tends to replace one of our senses, sight, by a metaphorical vibrotactile feedback representing the distance to close range object. We developed an electronic travel aid for visually impaired people, based on vibration motors and sonar. We assessed its ability to evolve and avoid obstacles in our surrounding environment. The next step consists in determining if such a principle can be applied to pass information about the environment within the field of teleoperation. Indeed, controlling a distant unmanned aerial vehicle is a difficult task due to limited visual feedback and absence of proprioceptive cue to feel the motion of the aircraft. Applying vibrotactile feedback that represents the effect of the wind seems to be an interesting approach for mental perception of the behavior of a remote controlled blimp. Wind is a natural phenomenon that we feel through our somatosensory system. At this point we wondered about the need of a metaphorical representation using vibrotactile stimulation. Even if it is rather easy to recreate wind using a fan, there is a lack of proper hardware to recreate directional wind. We built the first "wearable" haptic wind device for virtual reality enhancement and proved its usability to pass relevant directional information. Giving a direction in 3D space requires that the actuators are not located on the same plane as in our previous systems. We developed a wireless vibrotactile jacket containing 32 vibration motors and present its added value for a 3D searching space exercise in virtual environment, in correlation with visual and auditory cues. The second half of this document treats about development and application of a vibrotactile system in the challenging "Solar Impulse" project, aiming at performing a flight around the world relying only on renewable energy. A prototype aircraft has been built pushing forward the limits of the feasible in solar energy, composite materials, power management and human factor. As scientific consultant, our mission was to build an intelligent jacket in order to achieve symbodic relation between man and machine. A Symbodic system (SYMbiotic BODies) is a wearable device that supports symbiotic communication between the bodies of the pilot and of the machine. We proposed then a promising concept on how to improve awareness of the aircraft behavior. Passing from research concept to a concrete flying prototype is not an easy task, especially in terms of end-user acceptance: habits are strong for experienced pilot. But such an extraordinary airplane leads to some extraordinary aerodynamical behavior and the need of new visualization instruments. We developed an alert system for long flight duration based on the principle of the rumble strip installed on side of worldwide motor ways. Extensive tests have been performed by putting a subject in command of a highly realistic flight simulator for 48 hours straight. We showed that such system produces significant improvements of piloting performance under heavy sleep deprivation constraints.