A Proximity-Tactile Sensor to Detect Obstacles for a Cylindrical Arm

A new-type sensor has been developed which possesses the functions of proximity and tactile sensing. The sensor is attached to the cylindrical arm surface of a manipulator in order to carry out both obstacle detection and interference checking in real time for collision avoidance control. This paper first introduces the structure of the detector part of the sensor. The means by which it detects obstacles is then discussed: change of capacitance is used for proximity sensing, while change of resistance of a pressure sensitive conductive rubber sheet is used for tactile sensing. The changes on which the characteristics of the sensor is dependent are analyzed theoretically to show, with experimental values, that they are affected by the kinds and shapes of obstacles. Finally, the detection circuit of the sensor, which is composed mainly of an LC Hartley oscillator, and the resultant characteristics of the sensor, are shown. The sensor has characteristics of having a high credibility in detecting the existence of any near-by and adjacent obstacle and making a quick response to their contacts. Furthermore, the detector part is elastic but yet sturdy and simple.