Head Banging

I'm sure I've told a few of you, but ever since I can remember, Corbin likes to bang his head to sleep. He usually gets into position and sits down in his crib and bangs. Eventually he will be laying down banging the front of us head on his mattress until he slows down and eventually passes out (this usually only last about 4-5 mins). In the morning or after a nap I will find him with his legs sticking out of the crib bars banging his forehead on them. I've done some reading up on it and they say that it can be perfectly normal just as some children find comfort in sucking their thumb or rocking back and fourth. He has never been the type of child that liked to be rocked to sleep or cuddled for more than a min. He just pushes you away and tries to escape. Right now he has a little bruise on his forehead which he probably got from the head banging...poor little dude :(. I'm so tempted to pad the crib with pillows, but he's so strong, he'd probably pull them out of his crib.