NONCONTACT IMAGING PROXIMITY SENSOR FOR ROBOTIC INSPECTION AND ASSEMBLY

THE DEVELOPMENT OF A CAPACITIVE PROXIMITY SENSOR ARRAY FOR USE IN AUTOMATED ASSEMBLY AND INSPECTION OPERATIONS IS PRO- POSED. A TWO-DIMENSIONAL ARRAY OF SMALL CAPACITIVE SENSORS DETECTS THE DISTANCE BETWEEN EACH SENSOR TIP AND THE TARGET OBJECT. WHEN TOUCHING THE SURFACE OR OPERATING AT CLOSE DISTANCE, AN IMAGE OF THE SURFACE CONTOUR IS OBTAINED. THE SENSING PROCESS IS CONTROLLED BY A MICROPROCESSOR, WHICH ADDRESSES THE SENSORS IN SERIAL ORDER THROUGH A MULTIPLEXER SAMPLES THE DATA, AND LINEARIZES THEM ACCORDING TO THE CA- IBRATION CURVE. EACH SENSOR CONSISTS OF A THIN, SHORT LEAD (LINE CAPITANCE) EMBEDDED IN A HARD CERAMIC SUBSTRATE. THE SENSOR IS THERFORE RUGGED AND CAN, DUE TO ITS SMALL SIZE BE MOUNTED AT ALMOST ANY DESIRED LOCATION. WHEN COMPARED TO RESISTIVE TOUCH SENSORS, THE CAPACITIVE SEN- SING METHOD OFFERS POTENTIALLY HIGHER PACKAGE DENSITY AND IMAGE RESOLUTION; ANOTHER ADVANTAGE IS THE CAPABILITY TO DETECT THE PRESENCE OF OBJECTS WHILE APPROACHING, BEFORE