说明：  The whole code is divided into main function (main) and sub function: delay function (delay), buzzer function (speak), LED flashing function (LEDlight), car forward backward left turn right turn parking state control sub function, left and right motor PWM speed control sub function, Bluetooth interrupt service sub function, car tracking sub function_ Tracking (), car obstacle avoidance with a few cars_ In this paper, we propose a new method to solve this problem. When the program runs, define each variable first, then enter the main function to get the corresponding sub function to implement each function module.