Discussion and Conclusions CALIBRATION EXPERIMENT

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5.3.4 Discussion and Conclusions

Our calibration experiment explored the EMG value of the SCM muscle related to both neck support conditions, changes in head rotation angles and duration. The first result shows that when the neck is under the support condition, both SCM muscles showed a lower EMG value than under the without support condition. It is shown that when the neck is supported, the SCM muscle stress is lower than without support. Next, the mean rating of EMG values for a sitting person was increasing over time for both SCM muscles. The result showed that the EMG values for a sitting person in both neck support condition and without support condition were increasing over time. In the third finding, the mean rating of EMG value is increasing with the increase of head rotation angle. The finding is in line with the studies by Ylinen et al. 2003, Bexander et al. 2005, Moon et al. 2003 and Lin and Huang 2008. Lastly, there is a significant difference between right SCM muscle and left SCM muscle related to EMG value. In this section, we describe the calibration experiment to determine the difference of SCM muscle stress related to neck support conditions, time and head rotation angles. To do this, we developed the head rotation angle measurement apparatus with the support of the headset with laser beam and MP150 Biopac Systems to measure the SCM muscle stress of four participants. Based on the calibration experiment results, we concluded that the SCM muscle stress showed a significant difference related to neck support conditions, time and neck rotation angles. The right SCM muscle and left SCM muscle should be evaluated differently based on both SCM muscle showing significant differences. The main information gained from the calibration experiment is: 1 A sitting person in support condition demonstrated significantly lower mean ratings of SCM EMG value than under without support condition. 2 A sitting person in support and under without support condition presented significantly higher mean ratings of SCM EMG value over the increase of time. 153 3 A sitting person under support and under without support condition showed higher mean ratings of SCM EMG value over the increase of head rotation angles for both rotation directions. The results from the calibration experiment act as important input to calibrate our neck support design and validate our developed smart neck support system. 5.4 VALIDATION EXPERIMENT In this subsection, a validation experiment is reported. The validation experiment is to validate the developed smart neck support system SnS 2 in a simulated ‘real life’ setting. The design knowledge about SnS 2 was acquired from literature review findings as well as our survey results. Next, a functional prototype of SnS 2 was developed. The aim of SnS 2 is to support the passenger’s head and reduce passenger neck muscle stress during air travel adaptively and autonomously. An aircraft cabin simulator was utilised to conduct the validation experiment. The calibration experiment was conducted to gain information to be used for the validation experiment. The validation is an important process of SnS 2 . A similar validation process is also described by Rauterberg 2006 and Abrazhevich et al. 2009.

5.4.1 Research Question