A Real-Time Software Framework for Multi-axis Robotic Systems Using ROS 2 and EtherCAT

Multi-axis robotic systems demand high bandwidth and rapid control frequency updates for their effective operation. These systems are designed with distributed controller allowing sensor, control computation, and actuator nodes to communicate via network. In these systems, the high-level software controller handles tasks such as motion planning and control built on top of low-level control systems resulting in jitter and latencies introduced by software and communication components. The timing issues affect control, stability, and error correction capabilities ultimately degrading system performance and therefore, precise timing is essential for effective operation of control algorithms, particularly while computing state variables such as position, velocity, torque etc. The objective of this work is to investigate the impact of timing inaccuracies and to propose practical solution by integrating ROS 2 with EtherCAT. EtherCAT’s high bandwidth capability effectively manages the control of numerous joints, while ROS 2, with its Data Distribution Service (DDS) middleware, enhances real-time capabilities. To ensure the real-time capabilities of the ROS 2 communication stack and EtherCAT, a complete end-to-end ROS 2 managed node lifecycle pipeline has been implemented and real-time experiments are performed with PREEMPT_RT Linux on a motion control test setup to demonstrate the efficacy of the proposed approach.