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Haptic display transfers the sense of touch by applying forces, vibrations, or motions to the user. This article presents a novel bidirectional haptic display responsive to touch. The device is composed of a flexible tactile sensor and tactile actuator, and the actuator is actuated according to the touch signals from the tactile sensor. The tactile sensor is a thin array of resistive type sensors that covers the top of the soft dielectric elastomer actuator array. The tactile sensor measures the normal forces (0 $-$ 6 $N$ ) and positions of touches and then sends these signals to control the corresponding tactile actuator cells. The tactile actuator works within the frequency range of 0 $-$ 300 Hz, provides up to 520 $\mu \text{m}$ of displacement and, 600 mN of normal force, much greater than the human hand threshold (50 mN). And thus, the device can transfer different feelings to users. In this research, we develop and evaluate a stand-alone bidirectional haptic display. Then, we took the psychophysical test and introduced the master—slave system whereby the master device controls the slave device depending on the master input.

Hand reaching is a complex task that requires the integration of multiple sensory information from muscle, joints and the skin, and an internal model of the motor command. Recent studies in neuroscience highlighted the important role of touch for the control of hand movement while reaching for a target. In this article, present a novel device, the HaptiTrack device, to physically decouple tactile slip motion and hand movements. The new device generates precisely controlled 2D motion of a contact plate, measures contact forces, and provides hand and finger tracking through an external tracking system. By means of a control algorithm described in this manuscript, the velocity of tactile slip can be changed independently from the velocity of the hand sliding on the device's surface. Due to these multiple features, the device can be a powerful tool for the evaluation of tactile sense during hand reaching movements in healthy and pathological conditions.

This study proposes a methodology to deliver contact information on construction robots to the remote operator by transmitting measured collision vibrations, which are often beyond the human-perceivable range. We focus on the human capacity to discriminate the envelope of high-frequency vibrations as an essential cue to perceive contact materials and collision conditions. The proposed method preserves the envelope shapes with amplitude-modulated waves with a single carrier frequency in the human sensitive range. In the preliminary experiments, a miniature shovel digging experiment confirmed that the proposed method improves the discriminability of the contact materials and sliding velocities. A psychophysical experiment also showed that the participants could discriminate the envelope differences irrespective of the carrier frequency. The proposed method was applied to the tactile transmission system for a construction robot developed in the ImPACT program. A vibration sensor was attached on the robot arm, and the vibrotactile feedback was applied to the operator's wrist. Performance evaluations under a delicate teleoperated task (insertion of a bar into bricks) showed that the peak force was reduced by the proposed method significantly for two out of the three participants. The results show that our proposal could improve the maneuverability of teleoperation.

Human haptic perception system is complex, involving both cutaneous and kinesthetic receptors. These receptors work together and enable human to perceive the external world. To simulate immersive interaction with virtual objects in virtual reality scenarios haptic devices are desired to reproduce multiproperties of virtual objects, support multigestures of human hands to perform fine manipulation, produce haptic stimuli for simultaneously stimulating multireceptors (including cutaneous and kinesthetic receptors) of human haptic channel, and thus invoke realistic compound haptic sensations. In recent years, such multimodal haptic devices have emerged. In this paper, we survey the latest progress on multimodal haptic devices, identify the gaps, and put forward future research directions on the topic.

In this paper, we characterize the detection thresholds in six orthogonal modes of vibrotactile haptic display via stylus, including three orthogonal force directions and three orthogonal torque directions at the haptic interaction point. A psychophysical study is performed to determine detection thresholds over the frequency range 20-250Hz, for six distinct styluses. Analysis of variance is used to test the hypothesis that force signals, as well as torque signals, applied in different directions, have different detection thresholds. We find that people are less sensitive to force signals parallel to the stylus than to those orthogonal to the stylus at low frequencies, and far more sensitive to torque signals about the stylus than to those orthogonal to the stylus. Optimization techniques are used to determine four independent two-parameter models to describe the frequency-dependent thresholds for each of the orthogonal force and torque modes for a stylus that is approximately radially symmetric; six independent models are required if the stylus is not well approximated as radially symmetric. Finally, we provide a means to estimate the model parameters given stylus parameters, for a range of styluses, and to estimate the coupling between orthogonal modes.

Minimally invasive surgery has become widespread due to its smaller incisions and faster recovery times as compared to traditional surgery. However, laparoscopic surgery is not without challenges and certain serious safety risks for the patient. Trocar insertion is a necessary preparatory procedure for laparoscopic surgery during which a port is created through which laparoscopic instruments can be placed in the abdomen. This task is associated with a relatively high injury rate, typically attributed to surgical error. Previous studies have found that with sufficient training, these errors can be reduced or prevented, however, limited technologies exist to practice this procedure outside the operating room. This paper presents a novel admittance haptic display, based on a Stewart platform, that is designed to simulate the trocar insertion procedure. The device is shown to be able to render the necessary range of forces necessary to simulation trocar insertion. In addition, a simplified numerical model is developed which captures key characteristics of a typical trocar insertion force profile through multiple layers of the anterior abdominal wall. The device is shown to achieve promising preliminary results as a haptic display and medical training device.

We present a new rolling diaphragm actuator for transmitting forces in a teleoperated system. The initial application is for MR-guided biopsy procedures, providing accurate transmission of motions and forces between the fingertips of a physician and a biopsy needle being inserted into tissue. Desirable actuator qualities include low hysteresis, high axial stiffness, and long travel. The actuator uses an anisotropic laser-patterned fabric embedded in a soft silicone sleeve for a combination of low stretch in the axial direction and sufficient stretch in the radial direction so that a taper is not required; hence the actuator can have almost any length. We present results for a prototype input/output system with 6 cm stroke, 1 cm diameter, and a minimum force of 0.3 N to initiate motion. We compare its performance to a system using commercial rolling diaphragm actuators and show that the new system provides an improved combination of long stroke, high stiffness, and accurate transmission of fingertip forces.

Haptic displays have been developed to provide operators with rich tactile information using simple structures. In this study, a three-axis tactile actuator capable of thermal display was developed to deliver tactile senses more realistically and intuitively. The proposed haptic display uses pneumatic pressure to provide shear and normal tactile pressure through an inflation of the balloons inherent in the device. The device provides a lateral displacement of ±1.5 mm for shear haptic feedback and a vertical inflation of the balloon of up to 3.7 mm for normal haptic feedback. It is designed to deliver thermal feedback to the operator through the attachment of a heater to the finger stage of the device, in addition to mechanical haptic feedback. A custom-designed control module is employed to generate appropriate haptic feedback by computing signals from sensors or control computers. This control module has a manual gain control function to compensate for the force exerted on the device by the user’s fingers. Experimental results showed that it could improve the positional accuracy and linearity of the device and minimize hysteresis phenomena. The temperature of the device could be controlled by a pulse-width modulation signal from room temperature to 90 °C. Psychophysical experiments show that cognitive accuracy is affected by gain, and temperature is not significantly affected.

We demonstrate a wearable flexible electrostatic transducer (FET) matrix that conforms to the skin and can be used to generate complex haptic signals. The transducers consist of a pair of flexible electrodes that are attracted based on electrostatic force. We designed and built a 2 by 2 matrix of transducers from a pair of flexible films, with the design optimized for indentation into the skin. A transducer with a 10 mm by 10 mm footprint and a height of 2 mm effectively generated perceptible stimulus on the skin when operated at 150 V–250 V. Three psychophysical experiments were carried out to evaluate the properties of the new device as a wearable haptic display. Experiment 1 showed that the matrix of transducers was able to linearly boost perceived intensity when compared to a single transducer. Experiment 2 indicated that it was possible to indistinguishably replicate multi-frequency signals delivered to one transducer using multiple transducers that each operated at one of the frequencies. In Experiment 3, four movement-based stimulation patterns were designed using tactile illusion, and the identification rates were significantly above chance level. Our findings demonstrate that the compact, flexible, and scalable transducer array is well suited as a new type of actuator for wearable haptics research and applications.

As an alternative to enhance user’s experience in VR contents, we propose KABUTO, a head mounted haptic display designed to induce upper-body movement by the application of kinesthetic feedback to the head. KABUTO can provide impact and resistance by using flywheels and brakes in response to various head movements, as extensive head movements lead to dynamic movement throughout the upper body. We have also designed an application which enables the user to become a rhinoceros beetle.The user can feel the weight of the swinging horn or the impact of the horn flinging object. In the demonstration of it, we observed that KABUTO makes users move their upper body aggressively.

International audience; Despite the recent achievements in the development of open surgery tools, preserving the haptic capabilities during drilling tasks is still an open issue. In this paper, we propose a novel tool for hand-held drills composed of a cover for force sensing and a haptic display for force feedback. A pneumatic device has been developed to estimate the contact force occurring during the interaction between drill bit and bones. A performance comparison with a precise commercial force sensor proved the reliability of the measurements. A haptic ring is in charge of providing cutaneous sensations helping the surgeon in performing the task. The effectiveness of our method has been confirmed by experimental results and supported by statistical analysis.

A pneumatic haptic display for collaborative robotics applications is presented within this paper. The 3×3 tactor array consists of a polymeric parallelepiped with 9 cylindrical chambers (3mm diameter) providing haptic feedback by means of pneumatic actuation. A preliminary study, on four subjects, has been performed to identify the optimal pressure to deliver the tactile stimulation and assess system functionality. Four different spatial stimuli, based on the activation of different chambers of the tactor array, were provided at three different pressure levels (35, 70, 105 kPa). Results suggest that a pressure of 70 kPa leads to a detection accuracy of 96.9%. Further studies will focus on a deeper assessment of the tactile display using different configurations.

The effectiveness of haptic feedback devices highly depends on the perception of tactile stimuli, which differs across body parts and can be affected by movement. In this study, a novel wearable sensory feedback apparatus made of a pair of pressure-sensitive insoles and a belt equipped with vibrotactile units is presented; the device provides time-discrete vibrations around the waist, synchronized with biomechanically-relevant gait events during walking. Experiments with fifteen healthy volunteers were carried out to investigate users' tactile perception on the waist. Stimuli of different intensities were provided at twelve locations, each time synchronously with one pre-defined gait event (i.e. heel strike, flat foot or toe off), following a pseudo-random stimulation sequence. Reaction time, detection rate and localization accuracy were analyzed as functions of the stimulation level and site and the effect of gait events on perception was investigated. Results revealed that above-threshold stimuli (i.e. vibrations characterized by acceleration amplitudes of 1.92g and 2.13g and frequencies of 100 Hz and 150 Hz, respectively) can be effectively perceived in all the sites and successfully localized when the intertactor spacing is set to 10 cm. Moreover, it was found that perception of time-discrete vibrations was not affected by phase-related gating mechanisms, suggesting that the waist could be considered as a preferred body region for delivering haptic feedback during walking.

We propose ThermalBitDisplay, which is a haptic display with tiny Peltier devices providing thermal feedback perceived differently depending on the parts of the body touching them. We focus on the different thresholds of thermal sensitivity of body parts and the spatial summation of thermal perception. Utilizing these characteristics with ThermalBitDisplay, for example, enables providing thermal feedback perceived only on the lips, not on other parts of the body. New interactions using thermal feedback will have several usages for notifications, communication, alerts, and entertainment. We conducted user studies with 12 participants and demonstrations with more than 200 participants to validate the feasibility of ThermalBitDisplay and got feedback from them to improve our prototype.

When wearing a wire hanger on the head, an illusory force sense called the Hanger Reflex will occur. This phenomenon transpires not only at the head but also at the waists, wrists, and ankles. Dynamic control of the phenomenon by using pneumatic balloons has been proposed for the waist-type Hanger Reflex to enable direct rotation and translation of the user's body. However, this method is unsuitable for teaching different directions for the right and left legs, which is considered necessary for sports applications. In this study, we investigated which part of the leg is most effective for the direct rotation and translation of the leg. We also investigated the angle of the leg that was rotated when the Hanger Reflex device was attached to the thigh, knee, shin, and ankle, and the amount of translation. As a result, it was found that the most effective way to rotate and translate the leg was to rotate in the knee region, and that a greater extent of leg rotation was possible here than in other studies. These results suggest that a Hanger Reflex device is a possible candidate to rotate and translate the leg.

This paper proposes a grounded haptic display that can widely present a force sensation using a fishing rod. The proposed haptic display incorporates a fishing rod to present the force sensation at the user’s fingertip using a thread being reeled from the tip of the fishing rod. The multidirectional force sensation is presented by driving the base supporting the fishing rod using a pan-tilt mechanism, and wending the thread using the reel. The fishing rod is lightweight and moves at high speed. Additionally, it is possible to widely present the force by bending the fishing rod. This device requires conversion from the position of the user’s fingertip and magnitude of the force to the necessary winding force of the thread and the posture of the fishing rod. This study developed a control method and evaluated it by considering a case wherein the force to be presented is exerted in the vertical direction.

LinkRing is a novel wearable tactile display for providing multi-contact and multi-modal stimuli at the finger. The system of two five-bar linkage mechanisms is designed to operate with two independent contact points, which combined can provide such stimulation as shear force and twist stimuli, slippage, and pressure. The proposed display has a lightweight and easy to wear structure. Two experiments were carried out in order to determine the sensitivity of the finger surface, the first one aimed to determine the location of the contact points, and the other for discrimination the slippage with varying rates. The results of the experiments showed a high level of pattern recognition.

One type of assistive device for the blind has attempted to convert visual information into information that can be perceived through another sense, such as touch or hearing. A vibrotactile haptic display assistive device consists of an array of vibrating elements placed against the skin, allowing the blind individual to receive visual information through touch. However, these approaches have two significant technical challenges: large vibration element size and the number of microcontroller pins required for vibration control, both causing excessively low resolution of the device. Here, we propose and investigate a type of high-resolution vibrotactile haptic display which overcomes these challenges by utilizing a ‘microbeam’ as the vibrating element. These microbeams can then be actuated using only one microcontroller pin connected to a speaker or surface transducer. We propose that this approach could solve the low-resolution problem currently present in all haptic displays. In this paper, we present the results of an investigation into the manufacturability of such a device, simulation of the vibrational characteristics, and prototyping and experimental validation of the device concept.

Smart materials such as magnetorheological fluids (MRF) offer an interesting technology for use in haptic displays as changes in the magnetic field are rapid, reversible, and controllable. These interfaces have been evaluated in a number of medical and surgical simulators where they can provide cues regarding the viscoelastic properties of tissues. The objective of the present set of experiments was first to determine whether a shape embedded in the MRF could be precisely localized and second whether 10 shapes rendered in a MRF haptic display could be accurately identified. It was also of interest to determine how the information transfer associated with this type of haptic display compares to that achieved using other haptic channels of communication. The overall performance of participants at identifying the shapes rendered in the MRF was good with a mean score of 73 percent correct and an Information Transfer (IT) of 2.2 bits. Participants could also localize a rigid object in the display accurately. These findings indicate that this technology has potential for use in training manual palpation skills and in exploring haptic shape perception in dynamic environments.

Haptic interaction is a new interactive mode in the interaction technology between human and touch screens. In this work, we present an image-based haptic interaction system on touch screens. A novel haptic pen is designed for haptic display of visual image. It generates force feedback and tactile feedback through electromechanical structure and piezoelectric ceramics respectively. Haptic model of image is built by image processing and haptic rendering. In image processing, the image is decomposed into geometry and textures by local total variation for distinguishing contour shape from surface details. And the contour lines are extracted from the geometry based on the adaptive flow-based difference-of-Gaussians algorithm. Then the height information of image is recovered via shape from shading algorithm and expressed by electromechanical structure. Textures and contour lines are displayed by piezoelectric ceramics. Finally, the haptic perception experiment is conducted to investigate effect of perception with different haptic pens and modes of haptic interaction.

Making a virtual object shape recognizable using a haptic display is one of the major themes of haptic research. In previous works, multipoint haptic displays have been developed that had a high contact point density between the users’ finger skin and the virtual object. However, the ideal contact point density that enables intuitive shape recognition has not been determined yet. Meanwhile, there is also a fundamental problem; that is, real fingers and virtual objects do penetrate, which cannot be solved with such wearable displays. This article investigated the influence of both contact point density and penetration on the shape recognition performance. We prepared a real testing environment where the user touched the real object, and where we could simulate both the sparse contact point and the penetration. Specifically, users’ fingers wore thin film coated with glass particles and they touched the urethane foams that deformed flexibly. The result of experiments showed a broad trend where the sparseness of the contact and the softness of the object influenced the exploration time required to achieve recognition. In addition, the result suggested that the larger contact density could make up for the problem of penetration. We confirmed it by conducting two different tasks: (1) exploring the object surface with the index finger and (2) grasping the object surface with the thumb and the index finger.

© 2019 Copyright held by the owner/author(s). Haptic devices have been employed to immerse users in VR environments. In particular, hand and finger haptic devices have been deeply developed. However, this type of devices occludes hand detection for some tracking systems, or, for some other tracking systems, it is uncomfortable for the users to wear two different devices (haptic and tracking device) on both hands. We introduce RecyGlide, a novel wearable multimodal display located at the forearm. The RecyGlide is composed of inverted five-bar linkages with 2 degrees of freedom (DoF) and vibration motors (see Fig. 1.(a). The device provides multimodal tactile feedback such as slippage, force vector, pressure, and vibration. We tested the discrimination ability of monomodal and multimodal stimuli patterns on the forearm and confirmed that the multimodal patterns have higher recognition rate. This haptic device was used in VR applications, and we proved that it enhances VR experience and makes it more interactive.

Proficiency in any form of reading requires a considerable amount of practice. With exposure, people get better at recognising words, because they develop strategies that enable them to read faster. This paper describes a study investigating recognition of words encoded with a 6-channel vibrotactile display. We train 22 users to recognise ten letters of the English alphabet. Additionally, we repeatedly expose users to 12 words in the form of training and reinforcement testing. Then, we test participants on exposed and unexposed words to observe the effects of exposure to words. Our study shows that, with exposure to words, participants did significantly improve on recognition of exposed words. The findings suggest that such a word exposure technique could be used during the training of novice users in order to boost the word recognition of a particular dictionary of words.

Human perception of surface stickiness is closely related to intermittent slip dynamics, or stiction. In this work, we develop a method for real-time closed-loop rendering of surface stiction on an electroadhesive surface haptic display, and test it on a custom-built tribometer. We perform a psychophysical study to determine the effectiveness of a single, user-adjustable parameter on perceived surface stickiness, and elucidate what aspect of friction shapes the percept.

DeltaTouch is a novel wearable haptic display with inverted Delta structure for providing multimodal tactile stimuli at any point of the palm of Virtual Reality (VR) user or operator of remote robot. It is capable of generating 3D force vector at the contact point and presenting multimodal tactile sensation of weight, slippage, encounter, and texture. The BallFeel, BalanceIt, and AnimalFeel applications have been developed to demonstrate the capabilities of the proposed technology. In the first user study, we evaluated the perception of tactile cues delivered by the haptic display on a participants’ palm. The second experiment estimated the distinction in the perception of different forces generating by DeltaTouch on the human palm in a virtual weight sorting task. DeltaTouch can potentially bring a new level of immersion of the user in VR and improve the quality of teleoperation of the robot equipped with tactile and force sensors.

Stimulus distribution on a finger pad dynamically changes during dynamic interactions such as manipulation or handling of an object. This is caused by the magnitude and direction of the applied force on the finger pad and the elasticity of materials handled. Several past studies proposed wearable tactile systems. However, generation of distributed stimuli on a finger pad (multiple degrees of freedom stimulation) has not yet been achieved. Herein, we propose a rendering system for stimulus distribution on a finger pad. The proposed system consists of a display using multi-channel suction that presents distributed stimuli to a finger pad skin, and a real-time simulator that calculates dynamic pressure distribution on the finger pad when in contact with an elastic object. The developed display has good wearability as lightweight (5 g) and compact because it does not have an actuator on the fingertip in spite of multiple outputs (16 suction ports). We performed two different experiments using the proposed system. These experiments proved that it is possible to present different stimulus distribution depending on the contact posture between a finger and an object (experiment 1) and to present the softness of the virtual material with different elasticity values (experiment 2).

This paper seeks to better understand the use of haptic feedback in abstract, ubiquitous robotic interfaces. We introduce and provide preliminary evaluations of SwarmHaptics, a new type of haptic display using a swarm of small, wheeled robots. These robots move on a flat surface and apply haptic patterns to the user's hand, arm, or any other accessible body parts. We explore the design space of SwarmHaptics including individual and collective robot parameters, and demonstrate example scenarios including remote social touch using the Zooids platform. To gain insights into human perception, we applied haptic patterns with varying number of robots, force type, frequency, and amplitude and obtained user's perception in terms of emotion, urgency, and Human-Robot Interaction metrics. In a separate elicitation study, users generated a set of haptic patterns for social touch. The results from the two studies help inform how users perceive and generate haptic patterns with SwarmHaptics.

The fact that we can see each other face to face in the distance has become so natural with the appearance of video calls. However, the desire to touch each other in the distance is far from being resolved. We developed a pair of devices that can transmit touch sense through the shoulder such as tapping, caressing, and pressing. The touch sensors on a telepresence robot transmit touch feedback to a remote user wearing a haptic vest via wireless communication.

Midair haptic display using airborne ultrasound enables to give tactile feedback to a human body without wearing any devices. In the conventional ultrasound midair haptics system, the workspace was limited to the space of about 30 cm cube. In this paper, we integrate multiple ultrasound display units to achieve a large workspace. Our prototype system enables visuo-tactile interaction with AR images in a space of about 2 m cube.

LinkGlide is a novel wearable palm-worn tactile display to deliver multicontact and multimodal stimuli at the user’s palm. The array of inverted five-bar linkages generate three independent contact points to cover the whole palm area. The independent contact points allow to control different patterns in each of the points and provide multimodal tactile feedback, such as slippage, force vector, pressure, temperature, and vibration. With this novel haptic device, we can potentially achieve a highly immersive VR experience and make it more interactive.

Touch screens used as interfaces rarely give tactile feedback to users. We developed a electrostatic-force-based tactile display, however, it cannot express softness feelings on the screen. In this research, we attempted to display softness feeling by using multi-electrodes and a pressure sensor. When using our system, we observed that the user can feel change of the display area on the fingertip when his pressure toward the surface is changed.

In haptic interaction technology, texture haptic display is an important part. In order to perceive color image texture better, the haptic display methods of color texture based on force feedback and tactile feedback are proposed in this work. On the one hand, through the study of the physiological and psychological perception characteristics of color information, a new force rendering method of color image texture based on force feedback device is presented. The experimental results of color texture force perception show that the color texture force rendering algorithm in this paper works well. On the other hand, a color texture vibration tactile model is established based on the designed vibrotactile device. Its effectiveness is verified by vibration tactile perception experiment. Finally, for the color texture image of the real object surface, the force and vibrotactile display methods of color texture in this paper are used to conduct perception experiments and compared.

We examine how auditory displays, sonification and haptic interaction design can support visually impaired sound engineers, musicians and audio production specialists access to digital audio workstation. We describe a user-centred approach that incorporates various participatory design techniques to help make the design process accessible to this population of users. We also outline the audio-haptic designs that results from this process and reflect on the benefits and challenges that we encountered when applying these techniques in the context of designing support for audio editing.

In order to enhance the sense of reality haptic display based on image, it is widely expected to express various characteristics of the objects in the image using different kinds of haptic feedback. To this end, a multi-mode haptic display method of image was proposed in this paper, including the multi-feature extraction of image and the image expression with various types of haptic rendering. First, the device structure integrating force and vibrotactile feedbacks was designed for multi-mode haptic display. Meanwhile, the three-dimensional geometric shape, detail texture and outline of the object in the image were extracted by various image processing algorithms. Then, a rendering method for the object in the image was proposed based on the psychophysical experiments on the piezoelectric ceramic actuator. The 3D geometric shape, detail texture and outline of the object were rendered by force and vibration tactile feedbacks, respectively. Finally, these three features of the image were haptic expressed simultaneously by the integrated device. Haptic perception experiment results show that the multi-mode haptic display method can effectively improve the authenticity of haptic perception.

In this era of smart world several gadgets have been developed to make our lives easier. Great efforts have been put forth by the scholars worldwide to develop such smart gadgets for the welfare of blind. In case of haptic display units which refresh Braille characters for the visually impaired persons to read by the sense of touch also called as a dynamic Braille display. There have been several advancements evolved in such devices. Every design has both pros and cons. This paper tries to rectify particular cons of the existing Piezoelectric Braille display designs by updating it to the solenoid activated units and to make the haptic display units more reliable by empowering with IoT functionality. The developed prototype works with a 12 V DC supply line and a controller. In future, such proposed display units can be implemented on smart phones and to enhance the lives of differently abled citizen. The presented work can serve as a handy guideline for the fabrication and implementation of Solenoidal Braille systems.

This paper addresses sensory evaluation of cutting force for an encountered-type haptic interface using MR fluid. The encountered-type of haptic interface using MR fluid can display arbitrary force by controlling the magnitude of yield stress of MR fluid and an operator can feel resistance force by cutting the MR fluid directly with surgical instrument. In the previous studies, we tried to reproduce cutting force of authentic biological tissue, swine liver, by this haptic interface. However, we discovered that an operator did not feel same cutting force as in cutting the real swine liver even though the haptic interface reproduced the cutting force of real swine liver. Therefore, this paper carries out sensory evaluation of cutting force to clarify dominant factors of the cutting sensation and discusses how different between the real swine liver cutting and reproduced cutting force by the haptic interface. Then, we discuss possible improvement of the system for precisely reproducing the cutting sensation.

This paper investigates the effects of using passive haptic learning to train the skill of comprehending text from vibrotactile patterns. The method of transmitting messages, skin-reading, is effective at conveying rich information but its active training method requires full user attention, is demanding, time-consuming, and tedious. Passive haptic learning offers the possibility to learn in the background while performing another primary task. We present a study investigating the use of passive haptic learning to train for skin-reading.

In this paper, we present a calibration method for multi-unit midair haptic display that can cover a workspace larger than one-meter cube. In typical previous midair haptic displays, the workspace was smaller than a 30-cm cube, where the display target was limited to a hand and fingers. To achieve a large workspace covering a human upper body, we develop a system where arbitrarily located multiple display units with sensors can determine the relative positions and postures by a simple calibration process. In a prototype system using two units of 45 cm by 57 cm phased arrays, we examine the ultrasound convergence from the multiple units. We also show that the midair haptic stimulation is perceivable through clothes on the upper body.

Touch screen technology supplies a new approach to interact with virtual environments. For haptic interaction on a touch screen, haptic devices that are capable of simultaneously conveying tactile and force information to users are highly desired for enhancing the sense of reality and immersion. To this end, a prototype haptic interface, called MH-Pen, was developed and fabricated to display the virtual interactive information through multi-mode haptic feedback. The MH-Pen is a self-contained system that provides vibrotactile feedback and precise force feedback by integrating three types of actuators. In this paper, MH-Pen's design, specifications, and working principle are described. Subsequently, to accurately display the interaction force, a hybrid actuator was designed by combining a piston-type magnetorheological (MR) actuator and a voice coil motor (VCM), and a closed-loop control scheme was built to manage the hybrid actuator. Finally, we objectively and subjectively evaluated the force feedback performance and the effect of multi-mode haptic display of the MH-Pen through physical measurements and psychophysical experiments of virtual surface stiffness display. The results show that improving the precision of force feedback and using multi-mode haptic display are both useful and necessary to enhance the sense of human-computer interaction realism.

A key factor for reliable object manipulation is the tactile information provided by the skin of our hands. As this sensory information is so essential in our daily life it should also be provided during teleoperation of robotic devices or in the control of myoelectric prostheses. It is well-known that feeding back the tactile information to the user can lead to a more natural and intuitive control of robotic devices. However, in some applications it is difficult to use the hands as natural feedback channels since they may already be overloaded with other tasks or, e.g., in case of hand prostheses not accessible at all. Many alternatives for tactile feedback to the human hand have already been investigated. In particular, one approach shows that humans can integrate uni-directional (normal) force feedback at the toe into their sensorimotor-control loop. Extending this work, we investigate the human's capability to discriminate spatial forces at the bare front side of their toe. A state-of-the-art haptic feedback device was used to apply forces with three different amplitudes—2 N, 5 N, and 8 N—to subjects' right big toes. During the experiments, different force stimuli were presented, i.e., direction of the applied force was changed, such that tangential components occured. In total the four directions up (distal), down (proximal), left (medial), and right (lateral) were tested. The proportion of the tangential force was varied corresponding to a directional change of 5° to 25° with respect to the normal force. Given these force stimuli, the subjects' task was to identify the direction of the force change. We found the amplitude of the force as well as the proportion of tangential forces to have a significant influence on the success rate. Furthermore, the direction right showed a significantly different successrate from all other directions. The stimuli with a force amplitude of 8 N achieved success rates over 89% in all directions. The results of the user study provide evidence that the subjects were able to discriminate spatial forces at their toe within defined force amplitudes and tangential proportion.

The Hanger Reflex is a phenomenon in which the head rotates unintentionally when it is sandwiched by a wire hanger. The reflex is effectively generated by pressing on specific points, and can be reproduced by pressing with an actuator. We propose the HangerOVER, an HMD-embedded haptic display that can provide both force and motion senses using the Hanger Reflex. In this paper, we designed a mechanism of controlling the Hanger Reflex using air balloons for HMD embedded haptic display, and confirmed the occurrence of the Hanger Reflex.

The Hanger Reflex is a phenomenon in which the head rotates unintentionally when it is sandwiched by a wire hanger. The reflex is effectively generated by pressing on specific points, and can be reproduced by pressing with an actuator. We propose the HangerOVER, an HMD-embedded haptic display that can provide both force and motion senses using the Hanger Reflex. In this paper, we designed HangerOVER that HMD-embedded force and motion display using the Hanger Reflex, and developed four VR applications for demonstration.

A midair haptic display that provides a cooling sensation is developed in this study. Although a noncontact heat display using infrared rays has been reported, such an infrared display cannot cool the skin surface. In this study, we generate and control a straight, thin, long, air flow driven by an ultrasound-phased array and transport cold air to a localized spot on the users' skin. Since the air flow position and direction is electronically steerable, the display area can be controlled freely. A prototype of the proposed display was developed and the cooling performance was evaluated. We confirm that a small cool spot is created and shifted on a user's forearm based on our observations of the temporal changes in the skin temperature distribution using thermography.