the gps circuit are complicated,,,and i don't know,,,i want to build the simple one,,

what sensor can detect stair and pits?i want to put it at a blind stick for my final year project,,,

but the cost are high,,,and not all the blind people can buy it,,,i want put a sensor that can know the stair and pits,,,but i dont know the sensor and...

GPS module?means the instruction of direction the way that the blind people should go,,

what are the suggestion to improve the effectiveness of the blind stick? i want to add infrared distance sensor,,,another suggestion?