超声波发射部分的程序，结合接收部分，能实现超声波的定位功能，加上电机驱动实现购物车的定位跟随功能-Ultrasonic emission part of the process, combined with the receiving part, to achieve ultrasonic positioning, plus the motor drive for positioning the shopping cart feature to follow

超声波接收部分的程序，结合发射部分，能实现超声波的定位功能，加上电机驱动硬件实现购物车的定位跟随功能-Ultrasonic receiving part of the program, combined with the transmitter, to achieve ultrasonic positioning, plus the motor drive positioning hardware to follow the shopping cart feature