Electric field (EF) sensing is a method of proximity sensing that allows robot s and computers to detect, evaluate and work with objects in their vicinity. The technology is similar to that used in capacitive proximity sensing but incorporates refinements to analyze size, shape and contour.
In robot end effector s, EF sensing employs small, embedded metal electrodes connected to oscillators that produce high-frequency AC (alternating-current) electric fields. When anything that conducts electricity reasonably well, such as a person, animal, plant or metallic object, comes within a certain distance of the electrodes, the electric field fluctuates. The nature and extent of this change is sent to a microcomputer that compares the fluctuation pattern with stored patterns produced by known objects, allowing the end effector to easily grasp or manipulate the object.
The most sophisticated EF sensors can assemble detailed images. Using this technology in conjunction with other proximity-sensing methods such as machine vision , radar , sonar and fluxgate magnetometer s, a mobile robot can intelligently navigate in its environment. EF sensors are less likely than optical sensors to be "fooled" by objects having unfamiliar textures. EF sensors do not detect non-conductive materials such as glass, dry wood or plastic. Non-conductive objects appear transparent or invisible to EF sensing devices, allowing the sensors to detect and analyze conducting objects through non-conducting barriers.