We study the rectified transport of underdamped active noninteracting
particles in an asymmetric periodic potential. It is found that the ratchet
effect of active noninteracting particles occurs in a single direction (along
the easy direction of the substrate asymmetry) in the overdamped limit.
However, when the inertia is considered, it is possible to observe reversals of
the ratchet effect, where the motion is along the hard direction of the
substrate asymmetry. By changing the friction coefficient or the
self-propulsion force, the average velocity can change its direction several
times. Therefore, by suitably tailoring the parameters, underdamped active
particles with different self-propulsion forces can move in different
directions and can be separated.Comment: 7 pages, 7 figure