  The influence of random pinning on the vortex dynamics in a periodic square
potential under an external drive is investigated. Using theoretical approach
and numerical experiments, we found several dynamical phases of vortex motion
that are different from the ones for a regular pinning potential. Vortex
transfer is controlled by kinks and antikinks, which either preexist in the
system or appear spontaneously in pairs and then propagate in groups. When
kinks and antikinks collide, they annihilate.
