Abstract
An object shape recognizing method which analyzes an ultrasonic waveform is proposed. A non-directional pulse wave transmitted by an electric spark is employed. The experimental and theoretical waveforms reflected from several objects coincide well with each other and it is proved that each waveform has characteristics based on the surface shape of the reflected object. The pattern matching method, which compares a waveform in time domain directly with registered templates of waveforms and uses a cross-correlation index, is proposed. This method is advantageous compared with that using a power spectrum, since the frequency conversion procedure is not needed. An experiment of various objects recognition is carried out. The probability of recognition using a cross-correlation index is better than 98%. distance and the orientation of the object provided that the templates of corresponding distances and orientations are prepared in advance.