Yungjun Kim Seung-Yong Lee Sun Lim Implementation of PLC controller connected Gazebo-ROS to support IEC 61131-3. 1195-1198 2020 ETFA https://doi.org/10.1109/ETFA46521.2020.9212096 conf/etfa/2020 db/conf/etfa/etfa2020.html#KimLL20