In contrast to an ordinary ruler which is used for drawing lines and measuring length by manually moving its position, we have added wheels and a little intelligence to a ruler to create RulerBot. This is a research for assisting manual work. RulerBot can move toward anticipated positions to aid drawing a preset figure or detect the line drawn by the user to assist copying or supplementing the line. In this way, by integrating the actions of the human and machine, the user can draw complex shapes and figures with repetitive lines on paper.