单片机控制电动机的运转，使电动机向一个方向逐渐加速，然后减速，然后在向另一个方向逐渐加速，再减速，如此循环下去。-Microcontroller to control the motor operation, so motor to accelerate gradually in one direction, then slow down, and then a gradual acceleration in the other direction, then slow down, and so cycle continues.