Multifunctional optical proximity sensor using phase modulation

A proximity sensor is defined as the noncontact sensor of end-effector, and is one of the most important sensors for robot control. This paper deals with a new type of proximity sensor which has the capability of measuring spatial information, such as gap distance, inclination angles, and the angular positions of object particles. The measuring principle of the sensor is based on the phase shift of a modulated light signal. For this purpose, six light sources are placed on a cross-shaped pattern that is centered by a photodetector, and the power of light sources are modulated by different phase sine wave signals. The distance and angles can be measured by investigating the received phase information at the predetermined emitting pattern. By experimental measurement, the characteristics of this sensor are obtained and the effectiveness of the sensor is confirmed.