Abstract: Based on college teaching platform of infrared tracing car，to improve the anti-interference of the tracing car for faster and more stable tracing motion. On the basis of traditional circuit board of infrared tracing car，through addition of stringing and connection chip 74HC595 and multiplexer 54VHC4051，the experiment realized the time scanning and A/D sampling of tracing tube，and transfered the traditional hard threshold binarization into soft threshold quantization method，also realized the adjustment of position offset of the car based on PID algorithm. The comparison experiment showed that the new control strategied improved the space adaptability and appeared more stable for curve tracing.

Key words: infrared tracing, intelligent car, PID, time scanning