Ruutu, 33, played in 33 games for the New Jersey Devils last season, recording just one assist. He has 346 points in 735 career games.
Sheppard, 28, played for Kloten HC of the Swiss league in 2015-16. He last played in the NHL in 2014-15 with both the San Jose Sharks and New York Rangers.
Carr, 26, played with the Tulsa Oilers of the ECHL last season, winning 21 games.