Innovative Ultrasonic Sensors-based 2D Keypad Using Chain Code Algorithm

This paper describes an elegant method for recognizing the pattern of alphabets and distinguishing different points and their orientation based on two ultrasonic distance sensors. Sequence of line segments, formed by a set of different points, is determined by chain code algorithm. The result shows the simplicity of the system utilizing ultrasonic sensors, which can be developed into a new type of keypad.