[KenWittlief]

dead reckoning: any mode of navigation in which you are likely to end up dead :^)

the real defining difference is navigation with no outside references. Looking at your speedometer and driving for 30mph for 5 minutes, or running a boat engine as fast as it can go for 10 minutes, then turning left, going for 5 minutes...

if you use a compass, or GPS, or sensors that detect outside waypoints (lighthouses for example, or light beacons....) then you are not dead reckoning.

Even the use of a compass is in between, because it can tell you direction, but not distance - so with a compass you only know which way your are pointing, not where you are (and not really which way you are moving, because a compass in water cannot indicate the effects of current, wind and tides).

Im not sure that having feedback sensors on your wheels, or using a timer (counting clock pulses) makes a difference. Your wheels can slip, the tires can wear, another robot could be pushing you backwards while your wheels are spinning forwards, so I dont see how a wheel sensor is any more accurate or reliable than going by applied motor power and timer clicks?