LAUSR

In Yang et al. (2018), the authors derive an observation model of attitude quaternions from normalised accelerometer measurements. The method of Yang et al. builds up the linear measurement model via Taylor approximations. Some significant contributions and new filter designs are shown in this paper which deal with the problem of adaptive estimation. Regarding the factorization of the direction cosine matrix, it has been systematically described in Wu et al. (2018), but this has not been noticed by Yang et al. as this paper was published after the original submission of Yang et al. (2018). Yang et al. (2018) uses different compositions of a dynamical system that achieves the same result as in Wu et al. (2016).