Real-time Ethernet POWERLINK Communication for ROS. Part II. Hardware and Software

This research is focused on the integration of Ethernet POWERLINK (EPL) fieldbus with the Robotic Operating System (ROS) for real-time control tasks. In the first part of the research latencies and jitter introduced by the Linux operating system, ROS and the openPOWERLINK stack were analyzed and general concept of the novel EPL and ROS integration solution was introduced. In this part, we propose novel FPGA-based hardware for Ethernet POWERLINK resynchronization (ReSync board), which reduces jitter from the openPOWERLINK stack working in user-space and achieve low level of Start of Cycle frame jitter. Additionally corresponding software support for ReSync board and Application Programming Interface (API) is discussed. Finnally the results of experimental studies show, that proposed solutions allows achieve jitter below 15 microseconds in high-speed applications with a cycle of 10 ms or less on a low-performance hardware. Thus, proposed hardware solution is suitable for the most tasks in robot’s control systems, including even motor control for the applications, which do not require very high dynamics.