pi@raspberrypi ~ $ cd RobotUI/
pi@raspberrypi ~/RobotUI $ sudo python mpu.py
Traceback (most recent call last):
  File "mpu.py", line 9, in <module>
    from PID import PID
ImportError: cannot import name PID
pi@raspberrypi ~/RobotUI $ ls
mpu.py  PID.py  PID.pyc  robot.py  robot.py.save  robot_single.py
pi@raspberrypi ~/RobotUI $