Abstract
This paper describes a revised optical displacement measurement method to develop tactile sensors based on a suspension shell mechanism for dextrous fingers, so that the sensor can detect arbitrary force in direction, in addition to the position and pressure of an external force. To express variables of the position and orientation of the suspension-shell, five parameters regarding circumferential, directional, and inclinational displacements, and also axial and radial displacements are defined. Then a method of measuring these five parameters using inverse of optical projection is proposed. Point source of lights are attached on a medium section of the suspension shell and lighten a pinhole to produce light spots on a 2-D photosensor through a pinhole. Vector analysis for reverting the values of parameters are shown. Also, characteristics of measurement sensitivity depending on a position of the medium section in the dynamic range of the shell is evaluated. The method is characterized by the fact that only an optical set embedded in a cylindrical body is enough to measure the displacement paramerters and to make fingers smart.
