Mapping of Electrostatic Charge Using a Robot Controlled by a Computer

This paper is intended to fulfill two purposes. The first objective is to describe a particular laboratory system which maps the distribution and decay of residual electric fields around flat or curved insulating surfaces. Such a system may have applications in the noudestructive testing of insulation in the form of boards, cylinders, cones, and other shapes. The second objective is to point out the general usefulness of a system consisting of one or more sensors positioned by a robot controlled by a computer for reliably mapping in detail many kinds of fields in three dimensions. The particular implementation described uses a modified Microbot Teachmover robot to move the measuring head of a Monroe Type 230A field meter through a two-dimensional rectangular scanning grid over a flat sheet specimen. A DEC 11/23 MINC laboratory computer is used to both control the robot's movements, and to digitize and store in memory the readings of the field meter. The computer also plots a field map on the video screen during the scan, and stores field data on disk for later retrieval and processing. Results of scans of residual field are given for a typical plastic (polypropylene). Plots of the rate of change of residual field (obtained by taking the difference between scans) are also given. The significance of these results for nondestructive testing is discussed. The combination of one or more sensors, robot, and a computer, forms a flexible and convenient bench top system for the measurement, processing, real-time display, and storage of large amounts of data on two- and three-dimensional specimens.