Fig 1.
Example of use of PCA and CRP metrics on simulated datasets.
(a) Example of use of PCA (b) Example of use of CRP.
Fig 2.
The participant is wearing the exoskeleton (in yellow) and can use shoulder flexion (Θ1) and elbow flexion (Θ2) to reach targets (in green) on the screen in front of them.
Fig 3.
(A) datasets pertaining to kinematic time series for 2 joints. (B) Representation of joint positions using angle-angle plots. (C) PCA is computed on dataset A. (D) PCAA becomes the new reference frame and data of the second dataset are projected in this new reference frame. Another PCA is conducted on the projected data of dataset B. (E) Using equations at the bottom of C and D, the PCs of the second PCA can be expressed in terms of joint position. The coefficient before each joint can be extracted for each PC, this is the Joint Reprojection Weight (JRW). Each PC accounts for a percentage of the total variance of the dataset, but now the PCs of the 2 datasets account for the same percentage. (F) the results for the second dataset is subtracted from the reference dataset.
Fig 4.
(A) 2 datasets composed of a time series of 2 joint amplitudes. (B) joint velocities are computed and normalized to their range. (C) joint velocity is plotted with respect to position. (D) the angle between the velocity-position point and the horizontal (zero-velocity) axis is extracted for each timestamp. (E) The JsvCRP is calculated as the difference between the phase angles of two joints and the area between the 2 curves is computed.
Fig 5.
Four coordination strategies using shoulder flexion and elbow extension.
(A) Physiological Coordination Strategy. (B) Desynchronization of the 2 joints. (C) Use of the shoulder only. (D) Overuse of the elbow. The mean trajectory as well as the standard deviation are presented.
Fig 6.
JcvPCA results on experimental datasets.
Each coordination strategy data has been reprojected into the Physiological PCA reference frame and the Joint Reprojection Weight (JRW) are reported on the left. JRW of the of the physiological coordination strategy are indicated in blue, while divergent coordination strategies are indicated by orange bars. In the right panel, JcvPCA for each coordination strategy, with respect to the Physiological coordination strategy, are represented in green.
Fig 7.
CRP results between joints 1 and 2 for the 3 different coordination strategies, compared to the physiological CRP (in blue).
In green is the area between the 2 curves.