The PID controller generates a command signal to either modulate the brakes or motor up or down depending on {HEAD ~ the sign} of {TAIL ~ the command signal} 
of
The PID controller generates a command signal to either modulate the brakes or motor up or down depending on { HEAD ~ the sign } of { TAIL ~ the command signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL