First of all, pose. Secondly, different transfer functions. A wheel is a heavy physical thing that takes time to change. An accelerometer isn't, by design. The

First of all, pose. Secondly, different transfer functions. A wheel is a heavy physical thing that takes time to change. An accelerometer isn't, by design. The latter also redundantly measures acceleration direction rather than requiring it as an input. Thirdly, encoders don't always match accelerometers even in normal driving. Turns at intersections with tram tracks commonly cause these sorts of errors.