Arduino-RPi autonomous car, communication.

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I want to build an Arduino-RPi autonomous car. Arduino is responsible for low level control of motors, servos and ultrasonic. My question is, how can i do the communication from Arduino to ROS. Is it possible to do the communication via lib serial and make a node which take the data from arduino and publish them or subscribe them on ROS? Or i have to make a publisher or subscriber in Arduino with Rosserial Arduino. I am bit confused