Robert Downey Jr. is keen on "doing his part" for his family.

The 47-year-old actor is currently married to his wife Susan and the couple share eight-month-old son Exton together. Robert is also father to 19-year-old son Indio from a previous relationship.

The star honours his role as patriarch.

"I think the best part about being a dad is when your wife isn't mad at you, which means you're doing your part," Robert laughed to ET Online.

Robert is currently filming Iron Man 3.

The thespian is getting used to his superhero costume.

"[It's] more comfortable every time," Robert explained.

"They keep designing it to make it more sustainable so we can do more stuff in it."

Gwyneth Paltrow also stars in the sequel.

Robert has a fantastically strong friendship with the actress.

"He's like my big brother at this point," he joked.

Iron Man 3 will be released in US theatres May 3 2013.