BALTIMORE -- Orioles second baseman Brian Roberts will begin a minor league rehabilitation assignment on Wednesday, a significant step in his bid to return from a concussion that has kept him sidelined for more than a year.

Roberts, 34, last played in a baseball game on May 16, 2011. Since that time, the two-time All-Star has languished on the disabled list.

Although he's taken batting practice and fielded grounders with the Orioles, playing in a game -- albeit one with Double-A Bowie -- is a far more legitimate test of his readiness to return to the big leagues.

Asked to describe his emotions, Roberts said Tuesday, "Excited. Scared. A little bit of everything. It's been a long time coming, for sure."

Roberts will travel to nearby Bowie for a game against Richmond on Wednesday night. His minor league rehabilitation assignment can last no longer than 20 days.

"I'm pretty sure we'll use the 20," he said. "It's been over a year and I need to get some at-bats."

The plan is take it slowly at first and gradually pick up the pace.

"I need to get in there and see some pitches," he said. "The first few days, the first week, it's going to be two at-bats a day. It's going to take a little while to get built up to play every day on a back-to-back situation."

Roberts played in only 59 games in 2010 before going on the DL with a concussion. He returned last year, but was shelved after participating in only 39 games.

He compared this comeback to 2006, when he returned from elbow surgery to play in 138 games.

"Seven years ago, I had apprehension that, even though the doctors and everyone told me I was ready, that I was OK, that it wasn't going to happen," he said. "You're still scared. That's just the nature of going back out to a competitive environment when you've been hurt. Hopefully, once I get on the field and the first pitch is thrown, I'll just be playing baseball again."

There were times over the past year when Roberts wondered if he would ever feel right again, let alone play baseball.

"When there's days you are laying on the couch and can barely function, you're not even thinking about baseball," he said. "There were days that (baseball) never even crossed my mind, I was just trying to get back to a normal life. And then, as we continued to progress, I still had doubts about playing baseball. I had more confidence in being able to live a productive and enjoyable life. Now I'm beginning to think that playing baseball at a high level is a reality."