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Haptics is a tactile feedback technology that recreates the sense of touch to the user by applying forces, vibrations, or motions. Haptic devices should have a high performance in their output characteristics, for example, low friction in offstate, constant force with constant input, and quick response with dynamic input, in order to generate a sufficient sense of touch to human skin. We have focused on rapid response of magnetorheological fluid and decided to use it as the working material of the haptic device. There are several types of magnetorheological fluids available, and the effects of the different types of magnetorheological fluids on the response time of the haptic device have not yet been reported. The objective of this study is to experimentally investigate the response time of a magnetorheological fluid-based haptic device with two different types of magnetorheological fluids. We originally developed a single-disc type magnetorheological fluid-based haptic device, and its response time was investigated with two types of magnetorheological fluids. We set three experimental conditions with regard to the fluid gap and rotational velocity. We modeled the haptic devices as a classic first-order lag system, and the time constant of this system was assumed to be representative of the response time of the haptic device. According to the results, the response times of a sample tend to be smaller with the narrow gap (0.1 mm), whereas those of the other tend to be smaller with the large gap (0.5 mm). In addition, the response time is non-dimensioned and investigated with Mason number.

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A new optical system was developed and applied to automated separation of wood wastes, using a combined technique of visible-near-infrared (Vis-NIR) imaging analysis and chemometrics. Three kinds of typical wood wastes were used, i.e., non-treated, impregnated, and plastic-film overlaid wood. The classification model based on soft independent modeling of class analogy (SIMCA) was examined using the difference luminance brightness of a sample. Our newly developed system showed a good/promising performance in separation of wood wastes, with an average rate of correct separation of 89%. Hence, it is concluded that the system is efficiently feasible for online monitoring and separation of wood wastes in recycling mills.

Understanding the dynamic phenomena in grasping/cutting processes with scissors is important for the design of surgical robots and virtual reality systems. Here, we show the relationship between the mechanical stimuli and tactile sensations when forceps or scissors are used. Nineteen subjects grasped or cut objects and evaluated the tactile sensations in each of the processes. To conduct the tactile and mechanical evaluation simultaneously, subjects operated scissors that were fixed to a mechanical evaluation system. When subjects grasped urethane resin, stainless steel plate, and adhesive tape, soft, hard, and sticky feels were perceived, respectively. Dry, hard, and creaking feels were perceived in the paper cutting process. In addition, we observed four characteristic tangential force profiles in the processes. Regression analysis suggests the following findings: Hardness is perceived by the change of force and blade movement when the scissors make contact with the object. Stickiness is caused by the increase and decrease of force at the moment of peeling when the scissors break contact with the object. The cutting sensation is affected by fine force fluctuations during the scissors closing and the rapidly decreased force at the moment of cutting completion.Technologies 2018, 6, 66 2 of 9 paper or chicken [9]. Okamura et al. modeled the cutting force from the standpoints of friction, motion, and physical properties of objects [10]. Fujino et al. calculated the force applied to the hand, the restoring force of the leaf spring portion, and the friction inside the device when a test subject cut selected objects with micro shearing blades [11]. Weiss et al. developed two-dimensional, deformable, mass-spring models. They simulated the deformation of the tissue mesh from the position, speed, net force, and external force vector of each node on the virtual blade [12]. Fratu et al. calculated the forces applied to the scissors from a torque-angle response model synthesized from measurement data multiplied by a ratio that depends on the position of the cutting crack edge and the curve of the blades. The calculated forces were displayed by a 2 degree-of-freedom haptic scissors system [13]. Funahashi et al. displayed cutting sensation by combining vibrations and cutting sound [14].Scissors and forceps are used not only for cutting, but also for grasping objects. In this study, the mechanical stimuli were measured when a test subject grasped or cut an object with scissors. The objects were selected to analyze the relationship between tactile feels and physical stimuli. Nineteen subjects evaluated the tactile feels when they grasped or cut objects with different moduli of elasticity or different surface properties. Urethane resin, stainless steel plate, and adhesive tape were grasped with forceps to clarify the physical origin of the hardness and stickiness. To clarify the physical origin of the cutting sensation, the paper was cut with scissors. The mechanical stimuli and movements of the scissors during the grasping and ...