Biomimetic sonar recognizes objects using binaural information

An active sonar using Polaroid electrostatic transducers positioned at the end of a robot arm is described that adaptively changes its location and configuration in response to the echoes it observes in order to recognize an object. The sonar mimics biological echo-location systems, such as those employed by bats and dolphins, in that there is a center transmitter flanked by two adjustable receivers, the sonar has rotational and translational mobility, and the echo processing contains elements that have been observed in the mammalian auditory system. Using information in the echoes, the sonar translates in a horizontal plane and rotates in pitch and yaw to position an object at a standard location within the beam patterns. The transmitter points at the object to maximize the incident acoustic intensity and the receivers rotate to maximize the echo amplitude and the bandwidth, and to minimize the echo-producing region. This procedure results in a unique echo vector associated with each object at a given object pose. Recognition is accomplished by extracting 32 values from the binaural echo patterns and searching a data base that is constructed during a learning phase. The system operation is illustrated by having it recognize rubber O-rings of different sizes and by differentiating the head and tail sides of a coin.