Another concept for Security armor:

Essentially I like the idea of a flexible & strong form-fitting material underneath, with pieces of armor & tech layered. Also visors/helmets that give the Security Agent communications, and a HUD to pull up info on anyone, schematics of the Ark, etc.

[hider=Ark Patrol/Police Agents]
[img]https://s-media-cache-ak0.pinimg.com/736x/e8/49/9d/e8499de337b70a89793f79eedf71e7d4.jpg[/img]
[/hider]
Perhaps they would also carry shock batons, and other non-lethals, to subdue.

The Riot Police, however, (still looking for a good image) would have heavier armor with close-range weapons.