The development of a capacitive proximity sensor array for use in automated assembly and inspection operations is proposed. 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 calibration curve. Each sensor consists of a thin, short lead (line capacitance) embedded in a hard ceramic substrate. The sensor is therefore rugged and can, due to its small size, be mounted at almost any desired location. 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 use this proximity measurement feature to determine geometrical parameters in addition to proximity imaging, such as the angle of alignment between the end effector and a flat surface.The potential commercial application as described by the awardee: The imaging sensor will be applicable for precision monitoring of end effector position, automated assembly and inspection operations. The sensor will be rugged and versatile, offering high-resolution imaging and proximity sensing features, with applications throughout the robotics industry.
