Masashi Konyo

Artificial tactile feel display using soft gel actuators

It is difficult for the conventional tactile displays to express fine touch as a surface of cloth. A mechanical device appropriate for minute distributed stimuli on human skin does not exist. This paper proposes a ciliary device using soft high polymer gel actuators (ICPF) as a solution to this problem. This new device can generate various distributed stimuli to human sense receptors. It was experimentally confirmed that, combinations of vibratory stimuli of high frequency and low frequency produced complex tactile feels. Comparison of the artificial tactile feels and cloth material samples demonstrated that this device developed could display subtle distinction in the touch of cloth.

Development of a Texture Sensor Emulating the Tissue Structure and Perceptual Mechanism of Human Fingers

This paper discusses a novel approach in developing a texture sensor emulating the major features of a human finger. The aim of this study is to realize precise and quantitative texture sensing. Three physical properties, roughness, softness, and friction are known to constitute texture perception of humans. The sensor is designed to measure the three specific types of information by adopting the mechanism of human texture perception. First, four features of the human finger that were focused on in designing the novel sensor are introduced. Each feature is considered to play an important role in texture perception; the existence of nails and bone, the multiple layered structure of soft tissue, the distribution of mechanoreceptors, and the deployment of epidermal ridges. Next, detailed design of the texture sensor based on the design concept is explained, followed by evaluating experiments and analysis of the results. Finally, we conducted texture perceptive experiments of actual material using the developed sensor, thus achieving the information expected. Results show the potential of our approach.

A tactile synthesis method using multiple frequency vibrations for representing virtual touch

This paper presents a useful tactile display method that can control multiple tactile sensations such as roughness, pressure, and friction sensations using simple vibratory stimulations. Our concepts are based on two points: frequency range selection for making selective stimulation on different tactile receptors types and timing control of the stimulation in response to hand movements. The selective stimulations were realized by selecting reactive frequencies of vibratory stimulation based on temporal response characteristics of tactile receptors. For representing roughness sensation, vibrating frequencies were modulated in response to hand velocity considered as a temporal coding perception of FA I type receptor. Two reactive frequencies were also selected for representing pressure sensation and friction sensation corresponding to SA I and FA II type receptors respectively. A wearable tactile display using ICPF (ionic conducting polymer gel film) actuators verified our proposed methods. Finally, we conducted a total texture feeling display combined with our methods for roughness, pressure, and friction sensations in a parameterized manner. Comparison with real clothes showed that some combinations of multiple tactile sensations could express texture feels of the expected materials.

Active scope camera for urban search and rescue

A practical active scope camera for urban search and rescue is developed using ciliary vibration drive mechanism. Optimization of design parameters such as material, a diameter, density and an inclination angle of cilia, and specifications and density of vibration motors is performed on the basis of experimental evaluation of test pieces and prototypes with changing surface materials. A prototype of a scope camera 8 m long crawls at a maximum speed of 47 mm/s, climbs slopes of 20 deg, surmounts obstacles 200 mm high, follows walls, and turns on floors. Experiments at Collapsed House Simulation Facility of International Rescue System Institute, Kobe Laboratory demonstrate its practical advantage in rubble piles.

4A-5 Tactile Display of Surface Texture by use of Amplitude Modulation of Ultrasonic Vibration

In the present study, tactile display of surface texture by use of amplitude modulation of ultrasonic vibration is developed. First, systems are constructed to display artificial tactile sensation using ultrasonic vibrator. Then, sensory evaluation experiments are conducted to confirm that output stimulations in response to hand velocity is effective to realize an artificial tactile sensation. Next, it is confirmed that the proposed method to display roughness of a real cloth was more effective than existing method. Then, we evaluated the tactile sensation of a real cloth and a tactile display quantitatively using SD (semantic differential) method. As a result, at the evaluation item on roughness, the correlation coefficients between a real cloth and an artificial tactile sensation using proposed method was quite high. In conclusion, it is confirmed that realistic surface texture can be displayed by use of amplitude modulation of ultrasonic vibration

Development of velocity sensor using ionic polymer-metal composites

Conventional tactile sensors can only detect simple physical values such as pressure, but can hardly measure multi-directional movements in touch with the surface of objects. We propose a soft tactile sensor using an Ionic Polymer-Metal Composite (IPMC or known as ICPF). IPMC is excellent in softness, durability, easy molding, and so on. Many applications have been developed using as IPMC actuators. IPMC can also utilized as a sensor, because a voltage on the both ends of the film changes by adding mechanical stimuli and bending the film. It is found experimentally that IPMC has the characteristics as a speed sensor because the output voltages were in proportion to the velocities of the end of films by making vibrational motions. A tactile speed sensor that can measure the velocity vectors in 3-dimenstional movements was developed. The sensor has centroclinal structure made of silicone gel capsule, and four IPMC sensor modules were combined with the capsule inside in cross shape. The silicon gel capsule also seal in water, which is necessary for IPMC devices. The output voltages of each sensor were calibrated into the same maximum outputs because IPMC sensors have response variation. The amount of the velocity was estimated by calculating four outputs of each sensor modules. The direction of the movement can also be estimated by them only when the amount of the velocity exceeds the sufficient level. Experimental results show the sensor could estimate the velocity vector in real-time.

Tactile feel display for virtual active touch

In order to display delicate touch feeling of surface of some materials, active touch of human hand movements should be considered. In this paper, a wearable stimulation device that can produce various distributed stimuli on human skin in response to hand movements was developed using ICPF (Ionic Conducting Polymer gel Film) actuators. Characteristics of touch feel of roughness were measured using vibratory stimulation. The results showed that the threshold amplitude under active touch were smaller than under passive touch. A stimulation method which generate selective stimuli to sense receptors in accordance with velocities and accelerations of hand motions was proposed. It was confirmed experimentally that some kinds of pattern of driving waves express touch feels in response to hand movements.

Real-time remote transmission of multiple tactile properties through master-slave robot system

Remote transmission of high quality sense of touch requires the representation of multiple tactile properties and compensation of communication delay. We developed a real-time remote transmission system that can deliver multiple tactile properties using a master-slave robot system. First, we assessed what type of tactile properties should be transmitted and how to connect them in real time. Three tactile properties—roughness, friction, and softness—were transmitted on the basis of the real-time estimated physical properties of three main wavelengths, a kinetic friction coefficient, and spring constants, respectively. Tactile stimulations were generated in synchronization with hand exploration at the master side by using local tactile generation models to compensate for communication time delay. The transmission of multiple tactile properties was achieved by the integration and enhancement of our previously reported methods for vibrotactile displays and tactile sensors. A discrimination experiment using different materials showed the feasibility of the total system involving the three tactile properties.

Detectability and Perceptual Consequences of Delayed Feedback in a Vibrotactile Texture Display

This study estimated the maximum allowable system latency for haptic displays that produce tactile stimuli in response to the hand movements of users. In Experiment 1, two types of detection thresholds were estimated for the time delay of stimuli through psychophysical experiments involving 13 participants. One was a threshold for the users to notice the existence of a time delay. The other was a threshold for the users to experience changes in the perceived textures in comparison with stimuli with no time delay. The estimated thresholds were approximately 60 and 40 ms, respectively. In interviews, the participants reported that they experienced various types of subjective changes due to the time delay. In Experiment 2, the types of subjective sensations that might be altered by the time delay were investigated. The time delays were controlled based on the acceleration of the hand motions of the participants. The participants evaluated the differences in the perceived textures between the stimuli with a controlled time delay and ones with no delay. The results indicated that the participants associated the time-delayed stimuli with changes in mechanical parameters such as kinetic friction coefficient in addition to changes in the perceived roughness of the textures.

Observation and analysis of percolation behavior in carbon microcoils/silicone-rubber composite sheets

The electrical properties of carbon microcoils (CMCs)/ silicone-rubber composites were studied on the changes in the values of the electrical parameters (impedance, phase angle, resistance, and capacitance) as a function of the CMC content in the matrix, using an impedance analyzer in the frequency range from 40to200kHz. Percolation paths were observed at a 3wt% CMC content in the matrix. The properties of the composites were separated at the percolation threshold. The capacitance with a small value was dominant at CMC content less than 3wt%, and the resistance was dominant at CMC content higher than 3wt%.