As a major human sensory function, the implementation of the tactile sensation for the human-machine interface has been one of the core research interests for long time. In this paper, an innovative tactile display device based on the soft actuator technology is presented. Using electroactive polymer for the construction of the tactile display device, it can provide stimulation on the human skin without any additional electromechanical transmission. Softness and flexibility of the device structure, ease of fabrication, possibility for miniaturization, and low cost for mass production are the representative benefits of the presented device. Especially, the device application is open to many different purposes since the flexible structure offers the excellent adaptability to any contour of the human body. To prove its feasibility, a wearable device that can fit to the distal part of the human finger is presented and its performance is evaluated, experimentally.

Development of Soft-Actuator-Based Wearable Tactile Display

Virtual reality techniques allow one to interact with synthetic worlds, i.e. virtual environments. Tactile feedback means conveying parameters such as roughness, rigidity, and temperature. These information and many others are obtained thanks to the sense of touch. Tactile feedback is of prime importance in many applications. In this paper we examine the state-of-the-art in tactile interfaces design. Thorough reviews of the literature reveal a significant amount of publications concerning tactile human- machine interfaces, especially onwards the ~1990. This paper reports the progress in tactile interfaces technology in the following areas: teleoperation, telepresence, sensory substitution, 3D surface generation, Braille systems, laboratory prototypes, and games. Different parameters and specifications required to generate and feed back tactile sensation are summarized.

Tactile interfaces: a state-of-the-art survey

Electroactive polymer actuators stimulated by appropriate levels of electric field are particularly attractive for human-assist devices such as Braille. The development of a full page refreshable Braille display is very important for the integration of the visually impaired into the new era of communication. In this paper, development of a compact dielectric elastomer actuator suitable for Braille application is reported. The actuators are fabricated from commercially available silicone tubes. The tube has been rendered mechanically anisotropic through asymmetric levels of applied pretension in circumferential and axial directions in order to direct the actuation strain in the axial direction of the actuator. Key performance parameters, such as displacement, force, and response time of the actuator are investigated. The test results demonstrate the potential of the compact, lightweight, and low cost dielectric elastomer as actuators for a refreshable full page Braille display.

A compact dielectric elastomer tubular actuator for refreshable Braille displays

Robot-assisted surgery is characterized by a total loss of haptic feedback, requiring surgeons to rely solely on visual cues. A compact, flexible, and lightweight pneumatic balloon tactile display has been developed suitable for mounting on robotic surgical master controls. The tactile display consists of a molded polydimethylsiloxane substrate with cylindrical channels and a spin-coated silicone film that forms the array of balloons. Human perceptual studies were conducted to determine the optimal diameter, spatial resolution, and temporal resolution of the balloon actuator design. A balloon diameter of 3.0 mm provided the highest average accuracy (ges 95%) while offering five detectable inflation levels. Spatial accuracy in a two-actuator discrimination task reached 100% with 1.5 mm edge-to-edge spacing, and the accuracy of determining the order of two successive stimuli was greater than 90% when the time separation was 100 ms. Design optimization based on the results from this study enables the described tactile display to provide the effective tactile feedback that is otherwise unavailable during robotic surgery.

Optimization of a Pneumatic Balloon Tactile Display for Robot-Assisted Surgery Based on Human Perception

The tactile display is an important tool to help the human interact with machines by using feels of touch. In this paper, we present a multiply arrayed tactile display device with Dielectric Elastomer Actuator (DEA). The device employs the liquid coupling between the touch spot and the actuator as the transmission of force. It is designed to ensure the comfort of touch and the safety of operation for the users while contacting with the human skin. The operating principle is explained in details, and a systematic design analysis is given. The displacements of tactile display is about 240–120 μm at 3–10 Hz, which satisfies the frequency requirements for simulating the Merkel cells as well as the Meissner corpuscles and the force is over 40 mN to simulate the finger tip. In addition, a dedicated fabrication method and performance measurements are explained.

Design analysis and fabrication of arrayed tactile display based on dielectric elastomer actuator

This paper proposes a tactile display for presenting the moving or the shearing direction to the skin of a human finger. We consider stimulating tactile sense by vibration and the development of a tactile feedback system. The proposed vibro-tactile stimulator employs a number of vibrating pins to provide a ticking sensation to the human operator's skin. We used micro resonators driven by electromagnetic force to vibrating pins. We performed an experiment to present vibro-tactile stimulation using a single micro resonator, and confirmed the ability to perform vibro-tactile stimulation. Next we arrayed the micro resonators in a matrix state and constructed the tactile display. We made a tactile feedback experiment using this display. From the experimental results, it was made clear that the tactile display had the ability to present much information to a human finger.

F. Arai

Papers

Micro resonator using electromagnetic actuator for tactile display