RICHMOND, Va. -- The Redskins have signed offensive lineman Corey Robinson, the team announced Saturday. In a corresponding move, the team placed Trent Williams on the reserve/did not report list

Robinson, entering his sixth season in the NFL, worked out in front of members of the organization following the team's walkthrough Friday afternoon. The 27-year-old left tackle has started nine games since entering the NFL as a seventh-round selection in 2015. He last played for the Jacksonville Jaguars.

"We'll have workouts throughout the course of the season with guys and keep them on a 'hot-list' just in case something happens," head coach Jay Gruden told reporters Friday morning.

Robinson joins an offensive line unit still returning to full strength and without perennial Pro Bowl left tackle Trent Williams, who has yet to report to training camp. His absence has forced the team to start offseason signee Ereck Flowers at left tackle and fourth-round rookie Wes Martin at left guard. Ideally, Williams would start at left tackle and Martin and Flowers would compete for the starting job next to him.

When asked about the potential signing of an offensive lineman on Friday morning, Gruden pointed to the team's lack of offensive line depth rather than to Williams' holdout. The Redskins are also awaiting the return of center Chase Roullier and tackle Geron Christian, both of whom are still recovering from offseason surgery but should return soon, Gruden said.

"We need another tackle," Gruden said. "There aren't very many [young tackles] out there, so you might have to go the veteran route. There's a few other guys we might talk to here in the future, just for the depth wise. Right now, we're at 12 offensive linemen that are practicing, and that's way too short right now into training camp."