The Post has learned the Bulls are continuing to do their research on Mitchell Robinson ahead of the July 1 free-agency period. The Bulls could be the main competitors for Robinson if the Knicks don’t lock him up to a contract extension on June 30. The Bulls want to enhance their interior defense and believe Robinson could be a good fit slotted alongside offensive center Nikola Vucevic. Chicago reportedly has $49 million in cap space but that’s before they commit to free agent Zach Lavine — if they do commit.