Haptic perception is bidirectionally related to exploratory movements, which means that exploration influences perception, but perception also influences exploration. We can optimize or change exploratory movements according to the perception and/or the task, consciously or unconsciously. This paper presents a psychophysical experiment on active roughness perception to investigate movement changes as the haptic task changes. Exerted normal force and scanning velocity are measured in different perceptual tasks (discrimination or identification) using rough and smooth stimuli. The results show that humans use a greater variation in contact force for the smooth stimuli than for the rough stimuli. Moreover, they use higher scanning velocities and shorter break times between stimuli in the discrimination task than in the identification task. Thus, in roughness perception humans spontaneously use different strategies that seem effective for the perceptual task and the stimuli. A control task, in which the participants just explore the stimuli without any perceptual objective, shows that humans use a smaller contact force and a lower scanning velocity for the rough stimuli than for the smooth stimuli. Possibly, these strategies are related to aversiveness while exploring stimuli.

The results suggest that visual and tactile feedback can be useful for laparoscopic palpation; however, their effects depend on the means in which they are presented.

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We aim to achieve intraoperative localization of an early-stage gastric tumor that cannot be visually detected during laparoscopic surgery. In this study, we developed and evaluated a pneumatic tactile ring, which is a clinically applicable tactile device to provide instantaneous feedback from a tactile sensor directly manipulated by a surgeon. It was designed to be worn on the finger of the manipulating hand and to present pressure to the finger pad. It is lightweight, cost-effective, disposable, and sterilizable. We also developed a compact pneumatic drive unit to control the pressure and investigated its fundamental performance. The bandwidth of the pressure control was at least 1.3 Hz with a controllable range of up to 79.7 kPa. Moreover, a psychophysical experiment was performed to obtain the Weber ratio of the pressure and evaluate the effectiveness of the instantaneous tactile feedback of the sensor output through the tactile ring. The Weber ratio was 0.40 at the reference pressure of 22.7 kPa. The provided tactile feedback significantly reduced the absolute localization error and increased participants' confidence in their answers. It was shown that the tactile feedback through the ring is effective in laparoscopic tumor localization.

This study focuses on the measurement and evaluation of tactile sensations of various fabrics. First, tactile data on six pieces of underwear and seven pieces of polo shirts are collected through a questionnaire and the dominant factors of feelings of wearability are determined through factor analysis. Next, a tactile sensor with a polyvinylidene fluoride (PVDF) film as the sensory receptor and a sensor apparatus are assembled. The base of the sensor is an aluminum cylinder, around which a rubber sponge layer, a PVDF film, a protective layer of acetate film, and lace are stacked in sequence. The sensor is set on the rotational axis of a motor and a measurement object is placed on the sensor. Then, the sensor is turned to collect tactile information on the object. Features of the collected data are extracted by calculating the average amplitude of low frequency signals, the variance of sensor output, and the power intensity in a medium frequency range. Comparison with the results shows that the PVDF sensor well describes the human tactile perception.

The theoretical and experimental results show that the sensor is sensitive to the deformation due to contact with an object and has the potential to detect a lump in laparoscopic surgery.

The feeling of touch is an essential human sensation. Four types of mechanoreceptors (i.e., FA-I, SA-I, FA-II, and SA-II) in human skin signalize physical properties, such as shape, size, and texture, of an object that is touched and transmit the signal to the brain. Previous studies attempted to investigate the mechanical properties of skin microstructure and their effect on mechanoreceptors by using finite element modeling. However, very few studies have focused on the three-dimensional microstructure of dermal papillae, and this is related to that of FA-I receptors. A gap exists between conventional 2D models of dermal papillae and the natural configuration, which corresponds to a complex and uneven structure with depth. In this study, the three-dimensional microstructure of dermal papillae is modeled, and the differences between two-dimensional and three-dimensional aspects of dermal papillae on the strain energy density at receptor positions are examined. The three-dimensional microstructure has a focalizing effect and a localizing effect. Results also reveal the potential usefulness of these effects for tactile sensor design, and this may improve edge discrimination.

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