Escape the thief's security robots is the second mission in Going Commando. After Ratchet infiltrated the flying lab to obtain the experiment from the Unknown Thief, the Thief instead ambushed him, took the experiment, and left. He then had to flee the flying lab and return to his ship, the Star Explorer.
This mission, along with "Infiltrate the flying base", are the only two missions that visit the first path in the flying lab on Aranos, as the second visit to Aranos explores a different area entirely.
After the cutscene ends, you will immediately be attacked by a Megacorp Security Robot I - Chainsaw Model, a Megacorp Security Robot II - Flamethrower Model, and PX6 BladeBalls. Use the Gravity Bomb once to clear them out, and as more MSRs arrive from the ceiling, use the Lancer to destroy the rest. Take out all enemies in the room and a hatch will open on the left. Slide down this hatch to an open area.
In the open area, there are six flamethrower MSRs; use the Gravity Bomb to take out as many as you can (preferably aiming for one in the middle of the group), and then head right through the open hatch inside. After the short cutscene, several more MSRs will land, easily defeated with the Gravity Bomb. Take the elevator up to a very narrow corridor and use the Lancer to take out the next few enemies. In the next room, defeat all the BladeBalls and the MSRs that drop from the ceiling. Head to the following room, and in the fork, take the door on the left to an open area. This begins a cutscene, and the conclusion of the mission.
The story continues on Oozla, opening either the missions "Explore the swamp ruins" or "Find the store entrance", depending on which you'd rather complete first (though "Explore the swamp ruins" is slightly easier to finish first).