In the past, tactile displays were of one of two kinds: they were either shape displays, or relied on distributed vibrotactile stimulation. A tactile display device is described in this paper which is distinguished by the fact that it relies exclusively on lateral skin stretch stimulation. It is constructed from an array of 64 closely packed piezoelectric actuators connected to a membrane. The deformations of this membrane cause an array of 112 skin contactors to create programmable lateral stress fields in the skin of the finger pad. Some preliminary observations are reported with respect to the sensations that this kind of display can produce. INTRODUCTION Tactile displays are devices used to provide subjects with the sensation of touching objects directly with the skin. Previously reported tactile displays portray distributed tactile stimulation as a one of two possibilities [1]. One class of displays, termed "shape displays", typically consists of devices having a dense array of s...

Abstract A teletaction system uses a tactile display to present the user with information about texture, local shape, and/or local compliance. Current tactile displays are flat and rigid, and require precise machining and assembly of many parts. This paper describes the fabrication and performance of a one-piece pneumaticallyactuated tactile display molded from silicone rubber. Tactor spacing is 2.5 mm with 1 mm diameter tactor elements. Tactile display compliance ensures contact between the finger and tactile display at all times. Unlike previous pneumatic tactile displays, there is no chamber leakage and no seal friction. A psychophysics experiment showed that a a synthetic grating on the tactile display was perceived as well as a low-passfiltered real contact. 1

Tactile displays are used to convey small-scale force and shape information to the fingertip. We describe a 6 x 6 tactile shape display design that is low in cost and easily constructed. It uses commercially available RC servomotors to actuate an array of mechanical pins. The pins deflect a maximum of 2 mm, with a resolution of 0.1 mm. The pin center spacing is 2 mm and the pin diameter is 1 mm. For the maximum deflection of 2 mm, the display can represent frequencies up to 7.5 Hz; smaller deflections lead to achievable frequencies up to 25 Hz because the servos are slew rate limited. This design is well suited to tactile display research, as it offers reasonable performance in a robust and inexpensive package.

The suggestion that the body surface might be used as an additional means of presenting information to human-machine operators has been around in the literature for nearly 50 years. Although recent technological advances have made the possibility of using the body as a receptive surface much more realistic, the fundamental limitations on the human information processing of tactile stimuli presented across the body surface are, however, still largely unknown. This literature review provides an overview of studies that have attempted to use vibrotactile interfaces to convey information to human operators. The importance of investigating any possible central cognitive limitations (i.e., rather than the peripheral limitations, such as related to sensory masking, that were typically addressed in earlier research) on tactile processing for the most effective design of body interfaces is highlighted. The applicability of the constraints emerging from studies of tactile processing under conditions of unisensory (i.e., purely tactile) stimulus presentation, to more ecologically valid conditions of multisensory stimulation, is also discussed. Finally, the results obtained from recent studies of tactile information processing under conditions of multisensory stimulation are described, and their implications for haptic/tactile interface design elucidated.

We investigated the relative effectiveness of tangential versus normal displacements of skin for eliciting tactile sensations. Subjects adjusted the magnitude of slow tangential and oblique displacements of a cylindrical, flat-ended 1 mm diameter probe glued to the skin in order to match the perceived intensity of a reference displacement that indented the skin normal to the surface. At both the forearm and finger pad, subjects chose tangential displacements with magnitudes only 0.3 to 0.6-times the magnitude of the normal stimulus, indicating significantly higher sensitivity to tangential displacements (p<0.005). These findings are in rough agreement with a basic analysis of how normal and tangential loads transmit energy to mechanoreceptors at different depths in the tissue. Based on measurements of the mechanical impedance of the skin to normal and tangential displacements, these results were also expressed in terms of forces. At the forearm, subjects were more sensitive to tangential forces than normal force. However, at the fingerpad, sensitivity to tangential forces was lower than sensitivity to normal force, due to the approximately five-fold greater stiffness of the fingerpad to tangential traction. These results provide guidance for development of tactile displays: (1) When an actuator is limited primarily in terms of peak displacement (e.g., the maximum strain of a ceramic peizoelectric actuator) then tangential stimulation is a superior choice for both body sites we tested. (2) When an actuator is limited primarily in terms of peak force (e.g., the stall torque of a DC micromotor) tangential stimulation is the superior choice for the hairy skin, but normal stimulation is the better choice on the fingerpad. Key Words touch tactile display shear normal tangential mechanics SAI mechanoreceptor depth actuator strain energy density

Abstract- 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 humanmachine 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.

Abstract — A preliminary design of a remote palpation instrument for Minimally Invasive Surgery (MIS) is given. The lack of the tactile sense in MIS limits the surgeon’s abilities to examine and palpate internal organs. Based on this problem, the aim of this paper is to describe a surgical instrument which will serve as an extension of the surgeon’s fingers. A piezoelectric sensor array attached to the instrument’s end effector will provide tactile information, which will be sent to the surgeon’s fingers via a tactile display to provide a feeling of the shape and hardness of the tissue. The sensor array is 24 mm * 8 mm and consists of 30 piezoelectric sensors, while the tactile display constitutes of 30 micro motors adding up

A design of a new tactile shape display to be used in Minimally Invasive Surgery (MIS) is presented. It consists of 32 micro brushless motors in a 4-by-8 configuration, and the total size is 27 mm * 20 mm * 18 mm. The main restrictive design parameter is the size of the display because it should be attached to a laparoscopic grasper. Another important design parameter is modularity, as it is desirable to do experiments with several actuator pins. Each actuator has 3 mm indentation and can provide 1.7 N at a frequency of 2 Hz at full excursion. The pin spacing is 2.7 mm with a pin diameter of up to 2.65 mm. 1

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The design of a tactile shape display intended for Minimally Invasive Surgery (MIS) is presented. It consists of 32 micro brushless motors arranged in a 4-by-8 configuration, and the total size is 27 mm × 20 mm × 18 mm. The main restrictive design parameter is the size of the display as it will be attached to a laparoscopic grasper. Modularity is also crucial since it might be desirable to do experiments with other pins or effectors attached to the actuators. The tactel (TACTile ELement) spacing is 2.7 mm with a tactel diameter of maximum 2.6 mm. The display is tested with respect to pin force, positioning accuracy, bandwidth and stiffness. Results show that the tactels can provide an active force of 0.4-0.5 N at a frequency of close to 0.7 Hz at full excursion (3 mm). The testing also show that positioning accuracy is approximately 40 µm, while the stiffness is close to 50 N/mm. 1