Adaptive Phototransistor Sensor for Line Finding

Line finding is used by wheeled mobile robot for localization. A phototransistor array was designed to detect the line position relative to the robot. This sensor is composed of six phototransistors to detect the position of line on the floor relative to the wheeled mobile robot. Because the ambience may change with time and the floor colour may be different from one location to another, an adaptive scheme has been designed to find the line on the floor. This proposed scheme consists of three parts; modulation and demodulation, threshold recognition with k-means clustering, and line finding with fuzzy logic. Modulation and demodulation technique is used to tackle the problem of different ambience in the surrounding. K-means clustering is used to recognize the contrast in the colour of line and floor while fuzzy logic is used to find the line relative to the sensor. Experiments were conducted in a microcontroller and it was found out that this scheme can find the line on the floor with minimum error.