Optical proximity sensors for manipulators

A breadboard optical proximity sensor intended for application to remotely operated manipulators has been constructed and evaluated in the laboratory. The sensing head was 20 mm x 15 mm x 10 mm in size, and could be made considerably smaller. Several such devices could be conveniently mounted on a manipulator hand, for example, to align the hand with an object. Type 1 and Type 2 optical configurations are discussed, Type 1 having a sharply defined sensitive volume, Type 2 an extended one. The sensitive volume can be placed at any distance between 1 cm and approximately 1 m by choice of a replaceable prism. The Type 1 lateral resolution was 0.5 mm on one axis and 5 mm perpendicular to it for a unit focused at 7.5 cm. The corresponding resolution in the axial direction was 2.4 cm, but improvement to 0.5 cm is possible. The effect of surface reflectivity is discussed and possible modes of application are suggested.