这里的循迹是指小车在白色地板上循黑线行走，通常采取的方法是红外探测法。红外探测法，即利用红外线在不同颜色的物体表面具有不同的反射性质的特点，在小车行驶过程中不断地向地面发射红外光，当红外光遇到白色纸质地板时发生漫反射，反射光被装在小车上的接收管接收；如果遇到黑线则红外光被吸收，小车上的接收管接收不到红外光。单片机就是否收到反射回来的红外光为依据来确定黑线的位置和小车的行走路线。(he track here refers to the car walking along the black line on the white floor. The usual method is infrared detection. Infrared detection method, that is, using infrared light in different colors on the surface of the object has the characteristics of different reflection properties, in the course of the car is constantly transmitting infrared light to the ground, when the red light meets white paper floor, the diffuse reflection occurs, the reflected light is received on the receiving tube on the car; if the black line is encountered, the infrared ray is infrared. Light is absorbed, and the receiving tube on the car can not receive infrared light. The microcontroller determines the location of the black line and the walking route of the car on the basis of whether or not the reflected infrared light is received.)