抄録
In a previous report, a robot-type device with a tactile function was developed from a video taped study of human finger movements-the softness was evaluated, softness of human skin was measured and the softening effect of a facial treatment was confirmed. In this second report, an evaluation model of elasticity was extracted from a movement analysis of human touch, and the method of measuring elasticity was established by this robot-type device. This method was applied to the measurement of the dynamic properties of human skin.
In observation practical manipulation of elasticity of pliant objects such as the human cheek, a forefinger was used and an object was pushed against it, applying a small amount of pressure, then released. In order to measure the stroke and speed of forefinger movements, a luminous element diode was attached to the forefinger and its movement was measured by an infrared position-sensing system. The evaluation model of elasticity was described as the input of a stroke to the object and the response detected as a stress change.
The robot-type device consisted of a robot arm controlled by a microcomputer system and probe with a mounted mechanical strain gauge. With regards to measurement, the stroke and speed were controlled under conditions derived from the analysis of forefinger movements.
With the aim of extracting physical parameters that can explain elasticity, two types of pliant polymers differing in elasticity, were utilized. The rate of reaction force change in relation to the maximum value during the holding time was extracted as a parameter in order to distinguish elasticity from a qualitative comparison of two reaction force curves when objects were depressed and held in position.
In subsequent experiments, this method of measurement was used for measuring the dynamic properties of human skin. After experimental conditions such as the fixation of panelists' faces were established, correlation were obtained between parameters from the measurement by the robot type device and the elasticity evaluated by experts. As an example of an application of this device, the relationship between dynamic properties and human age were discussed.
These experiments suggest the probability of extension of palpation items with this device as well as its application in measuring other dynamic elements in the cosmetic field through an ergonomic approach to human tactility.
