Recognising plants with ultrasonic sensing for mobile robot navigation

Mobile robots navigate through many environments that include plants. A sensor that can recognise plants would be useful for navigation in these environments. Two problems make plant sensing difficult: plant similarity and plant asymmetry with rotation. A CTFM (continuously transmitted frequency modulated) ultrasonic sensor produces a signal that contains information about the geometric structure of plants. Correlation of echoes from many orientations show that plants can be recognised with sufficient accuracy for navigation.