An end‐effector based imaging proximity sensor

摘要

Abstract 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. Each capacitive sensor consists of a thin short lead (line capacitance) embedded in a hard ceramic substrate. The sensor array is rugged and can, due to its small size, be configured to almost any desired shape in order to examine even hard‐to‐reach surfaces. An electronic circuit converts the capacitance variations into voltage signals. The sensing process is controlled by a microcomputer, which addresses the sensors in serial order through a multiplexer, samples the data and linearizes them according to the calibration curve. When compared to resistive touch sensors, the capacitive sensing method offers potentially higher package density and image resolution; another advantage is the capability to detect the presence of objects while approaching, before physical contact is made. A proximity sensor array mounted on a robot end effector can determine geometrical parameters such as edges of surfaces, hole center locations, and the end effector pose (angle of alignment between end effector and target surface).