Neck Flexion Angle Estimation during Walking

Table 3

Mean of absolute error of the estimated neck angle after calibration steps (unit: degrees).

Walking case		Direct computation method	Fixed interval; T = 0.5 sec	Fixed interval; T = 0.75 sec	Fixed interval; T = 1 sec	Proposed flexible interval
3 km/h	Level 1	1.8637	0.5419	0.5403	0.4982	0.4836
	Level 2	1.8715	0.5579	0.5356	0.4999	0.4826
	Level 3	1.7772	0.5449	0.4932	0.4780	0.4545
	Level 4	1.8539	0.5632	0.5650	0.4928	0.4793
	Level 5	2.0296	0.6462	0.6297	0.5337	0.5074
	Mean	1.8792	0.5708	0.5528	0.5005	0.4815
4 km/h	Level 1	2.4324	0.7696	0.7460	0.8390	0.6590
	Level 2	2.2248	0.6280	0.6395	0.5494	0.5222
	Level 3	2.2666	0.7383	0.6646	0.6376	0.5636
	Level 4	2.2077	0.8018	0.5846	0.6797	0.5552
	Level 5	2.2607	0.6116	0.6482	0.6276	0.5534
	Mean	2.2784	0.7099	0.6566	0.6667	0.5707
5 km/h	Level 1	2.6015	0.5970	0.6359	0.5893	0.5434
	Level 2	2.5488	0.6479	0.6007	0.5484	0.5537
	Level 3	2.3671	0.5444	0.5038	0.5273	0.4856
	Level 4	2.3915	0.5932	0.6272	0.6478	0.5585
	Level 5	2.5111	0.6832	0.6684	0.7290	0.5866
	Mean	2.4840	0.6131	0.6072	0.6084	0.5456