Fig 1.
Left: a subject wearing MTw units; right: MTw unit and schematic of the test field.
Fig 2.
(a) ext-acc variable and (b) pca-acc variable.
Fig 3.
TD comparison between the variables.
External acceleration signal in the directions of x- and y-axis of the n-frame and the principal axis (pca-acc) during 7 s of outdoor walking trial.
Fig 4.
FD comparison between the variables.
Fourier transform magnitude for the pca-acc and ext-acc signals from one subject.
Table 1.
Walking speed estimation error (different variables).
Fig 5.
Regression and Bland-Altman plots.
(a) Regression analysis for the generalized GPR model and (b) Bland-Altman plot for comparison of the reference walking speed values and the predicted values from the generalized GPR model using the pca-acc variable. The upper and lower horizontal lines show the 95% limits of agreement and the middle horizontal line shows the bias.
Table 2.
Walking speed estimation error (different models).
Fig 6.
Comparison of the reference walking speed values and the predicted values based on the generalized LSR-Lasso model.
Fig 7.
Estimated walking speed based on the generalized GPR model and the one from GPS-IMU fusion during a 12-min outdoor walking trial.