Sensors: Vision and tactile

Several techniques are presented to obtain 2D grey-value images and distance images. In these sensor systems different principles may be used to select the image points of which the grey-value is measured. The scanning may be presented in the light source, in the sensor, in the movement of the object or in a combination of these. Distance images may be obtained by triangulation of points in the scene between lightbeam and sensor. The sensors are based on scanning beams, planes of light or space encoding. Commonly used vision sensors such as video pick-up tubes, CCD arrays and Position Sensitive Detectors (PSD) are discussed. Tactile sensors are based on the measurement of surface deformation by optoelectronic, capacitive, magnetic, piezoelectric or piezoresistive transduction. Tactile arrays offer the possibility of obtaining pressure images which can be processed in the same way as if they are the result of a vision sensor.