Flood started his first match since August following a hamstring injury, while Robson came off the bench to make his first appearance since the opening day of the campaign, having worked his way to fitness after a knee operation.
The Dons boss said: "One or two of the boys were feeling the effects, Willo Flood took a heavy ankle knock and the physio thought he should come off at half-time, but Willo asked to give it five minutes and I never asked again how he was.
"Willo started the second half brilliantly, and he more than anyone gave us a bit of momentum. We started the second half with more purpose, culminating on the goal."
"Robson came on and gave the crowd a lift at the right time, and it was the crowd who helped us grind out the win."
On top of the ankle knock suffered by Flood, McInnes was left with a concern over Ryan Jack, adding: "Joe Shaughnessy had committed a foul after being booked, and with Gary Mackay-Steven drifting over there I thought the best way to get Robson on was to take Joe off and move Ryan to right-back.
"Ten minutes later, Ryan went down with a tight hamstring. We got him off in time, but it meant we had to finish with Michael Hector at right-back."