**5. Conclusions**

Eating with a spoon is characterized by several salient kinematic features: a unidirectional change in yaw angle for each movement phase, a short-duration change in roll and in pitch angle during the initial scooping phase, followed by relatively stable roll and pitch angles during the transport to mouth phase [14]. This work shows that automatic identification of these salient events is possible. We sugges<sup>t</sup> that using these measures to describe self-feeding kinematics, makes it possible to tap into functionally-relevant variables associated with e fficient performance. In the future, these measures can potentially be used to provide targeted knowledge of performance feedback [32] in order to modify self-feeding performance in people with motor impairments.

In this study, measures of duration and of angular range of motion demonstrated excellent validity. Furthermore, we demonstrate here that kinematic measures based on angular velocity have higher concurrent validity compared with measures based on linear velocity and acceleration (peak velocity, fluency) when extracted from a low-cost inertial sensor, possibly due to the larger computational cost and errors associated with obtaining the latter measures. Future studies will be performed to validate this approach with atypical populations (e.g., cerebral palsy) where self-feeding kinematics are impaired [28]. In addition, additional information will be integrated to complement the DataSpoon, such as a time-coupled trunk movement sensor [22] which will assist identification of postural compensations.

**Author Contributions:** Conceptualization, T.K., P.L.W., O.Z., T.K.-C.; methodology, T.K., J.F., P.L.W., O.Z.; software, T.K., A.B., J.F.; validation, P.L.W., O.Z., J.F.; formal analysis, T.K.; investigation, T.K.-C., T.K., J.F.; resources, J.F.; data curation, T.K.; writing—original draft preparation, T.K., J.F. writing—review and editing, P.L.W., O.Z., T.K.-C., A.B.; visualization, T.K., J.F.; supervision, P.L.W.; project administration, J.F.; funding acquisition, J.F. All authors have read and agreed to the published version of the manuscript.

**Funding:** Funding was partially provided by the Israeli Center of Research Excellence "Learning in a Networked Society", gran<sup>t</sup> number 1716/12.

**Conflicts of Interest:** The authors declare no conflict of interest.
