Proceed along beneath the floor and launch a Multi-takedown from below. Arkham Knight's goons have swarmed the control room but, luckily, Batman has given them the slip. When you do, the action automatically returns to Batman in the watch tower.
Next, deploy your Power Winch at the hook point and pull the ramp backward. In order to reach your target on the building above, come to a halt near the yellow ramp and enter Battle Mode.
Continue picking them off from behind (don't forget to check out the upper level if you're struggling to find them) and, with all five Cobras defeated, slip the Batmobile back into standard drive mode, Finally, follow the waypoint marker towards the missile launcher. Unsurprisingly, you'll need to bring these down too in order to proceed. Once you've eliminated the first couple of Cobras, Arkham Knight deploys two more.