I am trying to set up an Extended Kalman Filter, but I probably have some form of simple error. With a single Twist and a single Odometry input, the output Odometry shows the vehicle moving even when stationary, then steadily accelerating as the vehicle begins to move; it is like there is some hidden velocity component in my model.

My twist0 Twist data starts at all zeros (including covariance, although I have valid values in the ekf_template.yaml file), in the frameid dr, which is my vehicle zero point on start-up relative to the map, which RViz says is (-24762, -53804) - I've set `twodmode. Myodom0` data starts with a pose position of (-24762, -53804) and a twist of all zeros, with frameid map and childframeid dr.

The vehicle is not moving, but I see the odometry/filtered topic moving forward, and with both the yellow and purple areas growing as it moves. The topic has a pose growing away from zero, and a linear x twist of 2.6. frameid is dr and childframeid of `baselink`.

I'm sure I've got something obvious wrong; this is part of a larger system so I have turned off the publish_tf option.