Abstract
The miniaturized version of a finger-shaped tactile sensor previously reported in scaled-up version is developed. The developed tactile sensor is capable of detecting the contact location and the normal to the surface of the object at the contact by applying optical phenomena. Infrared LEDs are installed for the light source at the edge of the hemispherical optical waveguide with elastic cover. A fiber optics plate (FOP) and a position sensitive detector (PSD) is employed for the image guide and the optical detector, respectively. The FOP consists of high-density bundled optical fibers and it can transmit the optical image from the optical waveguide to the surface of the PSD. The injected light from LEDs into the waveguide maintains total internal reflection at the surface of the waveguide and is enclosed within it. When an object comes in contact with the sensor, the cover depresses and touches the waveguide. At that moment, scattered light arises at the point of contact caused by the change of the reflection condition. The scattered light reaches to the PSD through the FOP and the position of the optical input is converted to the electric signal at the surface of the PSD. By processing this signal in the computer, it is possible to detect the contact location and the normal to the surface of the object.
The above-mentioned principle and the integrated structure of the developed sensor are described in detail, and the signal processing is formulated. Furthermore, the accuracy of the contact detection for static contact and the dynamic response for the intermittent contact of the sensor are experimentally evaluated.
