Jul 31, 2010 #1 A abacusdheda Junior Member level 1 Joined Dec 28, 2009 Messages 15 Helped 0 Reputation 0 Reaction score 0 Trophy points 1,281 Location INDIA Activity points 1,381 i want my bot to detect a block like this at a range of 20 to 25cm . so what sensors i should use??