Function set_current_thread_scheduler_priority 

pub fn set_current_thread_scheduler_priority(
    priority: i32,
) -> Result<(), String>

Puts the calling thread on SCHED_FIFO at priority (1 to 99 on Linux).

The generalisation of set_current_thread_to_highest_scheduler_priority, which is this at sched_get_priority_max(SCHED_FIFO). A lower priority is what a program that runs other realtime threads (a robot-side driver, a second arm) gives a crate::robot::target_control loop; the Err text is libfranka’s.