Keep Calm and Carry On was a poster produced by the British government in 1939 during the beginning of World War II, intended to raise the morale of the British public in the event of invasion. It was little known and never used.
It’s not easy to translate with the robots because of “carry on”, however, here are some ideas:
Garde ton calme et persévère.
Gardez votre calme et persévérez.
Garde ton calme et continue de l’avant.
Garde ton calme et continue.
The main difference between them, as you can see, is the choice between you and “vous” – use whichever is appropriate.
Also, the verbs perseverez or continue are used. Again, you decide whether to use “continue” or “persevere”.
:-)