A method for detecting {HEAD ~ the speed} of a sledge motor in {TAIL ~ an optical storage device} 
A method for detecting { HEAD ~ the speed } of a sledge motor in { TAIL ~ an optical storage device }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL