Xenomai

An open-source framework that adds hard real-time capability to Linux, common in low-level robot control.

Xenomai is an open-source real-time extension framework for Linux, originally started by Philippe Gerum. Its classic approach is a “dual kernel” design: a real-time kernel (Cobalt) runs alongside ordinary Linux, with real-time tasks scheduled by Cobalt at top priority while Linux runs only when the system is otherwise idle, pushing the timing jitter of a control loop (the variation in exactly when each cycle actually executes) down to the microsecond range. Robot joint control often needs a loop running at 1 kHz or higher that can never run late, which stock Linux cannot reliably guarantee, so Xenomai is commonly paired with an EtherCAT master on an industrial control computer. The other common route is patching Linux with PREEMPT_RT, which is simpler to set up but usually can't match the dual-kernel approach's worst-case latency.

ExampleOn an industrial PC, run the IgH EtherCAT master under Xenomai, sending position commands to each joint driver on a robot arm at a 1 kHz cycle.

Related

Real-Time Operating System (RTOS) · PREEMPT_RT · Hard Real-Time · EtherCAT Master (SOEM / IgH) · Jitter (Timing Jitter) · Real-Time Control

Sources

Xenomai 官网 (Chinese)
Xenomai - Wikipedia