People are able to perceive a number of spatial and other properties of objectswithout visual information by wielding and hefting objects. This kind of touch isreferred to as “dynamic touch”, and it is related to the moment of inertia of objects.This paper proposes a method for varying the superficial moment of inertia byexternally generating a torque in order to present information for dynamic touch.For generating external torques, a gyroscope capable of generating an externalforce with no mounting or grounding is used as a haptic force generator. It isshown theoretically that a gyroscope can change the superficial moment of inertiaof a rod. An experimental haptic force generator consists of a gyroscope and sensorsfor detecting rod-wielding.The perceptual characteristics of haptic force generator are determined by performingtwo experiments. The first experiment is a perception experiment to determinewhether subjects are able to discriminate between different superficial momentsof inertia presented by haptic force generator. The subjects are easily ableto detect changes in the superficial moment of inertia. In the second experiment,the perceptual characteristics of wielding motion generated by haptic force generatoris evaluated using psychophysical, electromyographic and kinematic methods.Furthermore, the perceptual characteristics of wielding motion by an actual rod areexamined using the same method. By comparing the perceptual characteristics ofusing an actual rod, it is found that the wielding perception of haptic force generatoris affected by an external torque in the direction of palmar and dorsiflexion.In conclusion, the haptic force generator using a gyroscope is capable of generatingvirtual dynamic touch. This device can be used to present information for dynamictouch in welfare engineering and cognitive psychology applications.
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