Real time ROS node without ROS control, orocos?
I have a hardware controller node which controls three motors using SOEM with Ethercat. I use a ROS timer in this node with 500 Hz control frequency. However, I find out that the timer is not accurate at all; sometimes there is a 100ms delay and cause the Ethercat to send 'stop-working' commands to motors. So I plan to use a RT_PREEMPT patch to the current Linux kernel to solve the 'jitter' problem. However, I want to solve this problem with least effort possible. So what is the possible shortcut? And are there any problems if I only use the RT_PREEMPT patch without using ros_control or orocos framework as many people are actually using them?
Another problem is how to choose a suitable realtime priority for my hardware controller node?