closely to state and we should be able to distill from that a likely estimate of the state or a distribution around some mode maybe of what the state might be how about a mobile robot inside a building the state could be position and heading is let's say a slow robot is just slowly moving you don't care about velocity just the position in the direction it's facing then sense source odometry which is sensing motion of the actuators for example wheel encoders so on your wheels you might measure how much your wheel has turned if you didn't