nfrared detection, that is to say, the use of infrared in different colors of the physical surface has different characteristics of reflection. In the process of the car driving, infrared light is continuously transmitted to the ground. When the red light meets the white ground, it will diffuse, and the reflected light will be received by the receiving tube installed on the car; if it meets the black line, the infrared light will be absorbed, and the receiving tube on the car will not receive the signal, and then the LM324 is used as the comparator to collect the high and low level, so as to realize the signal detection. Obstacle avoidance is the same principle. The circuit diagram is shown in Figure 3.4.