Ferromagnetic (FM) skyrmions observed in ferromagnet/heavy-metal multilayers are considered as promising candidates for future spintronic racetrack memory. Unfortunately, the Magnus force acting on the skyrmions seriously limits this application. In contrast, that force experienced by the two sublattices of an antiferromagnetic (AFM) skyrmion can be cancelled completely, so that they are expected to move straightly along the applied electric current with greatly enhanced velocity. However, Monte Carlo simulations done by previous authors show that in the presence of Dzyaloshinsky-Moriya (DM) i...