They go into the second day at Scarborough today on 315-8 against Yorkshire, thanks largely to Ed Joyce's 130.
Joyce was out off the final delivery of the first day but that could not tarnish Robinson's satisfaction.
The Sussex boss said: "I am very happy with the way things went after we had been put in to bat.
"The great partnership between Ed Joyce and Craig Cachopa took the sting out of the attack and was the feature of the day.
"Ed is an outstanding player who has the capacity to go on. He doesn't bat to his ego and today he was back to his best.
"I had a feeling that to bat first was the right thing to do because the pitch feels a bit crusty and it will be interesting to see if it takes spin later on.
"The ball seamed about all day and we knew the importance of getting through the first session.''