用89C52实现占空比均匀调整，实现电机的均匀加速到全速，再稳速，然后均匀减速到零-Duty cycle with 89C52 to achieve even distribution, the uniformity of the motor to accelerate to full speed, then steady speed, then slow down to zero even

三路循迹小车的循迹，其中包括了超声波雷达测距，步进电机工作以方便雷达对左右两侧物体测距后显示在1602上，其中为了方便使用这里对程序分列和合并在一起。基于89c52芯片-Three-way tracking car tracking, including ultrasonic radar range, in order to facilitate the work of the stepping motor to the left and right sides of the object ra