Evidence for Composite Cost Functions in Arm Movement Planning: An Inverse Optimal Control Approach
Figure 4
Quantitative experimental results.
A. Reached point (final finger position) on the bar for each initial posture from P1 to P5 (RP parameter). The unit on the vertical bar is normalized by the arm length (percentage). The horizontal zero baseline is the level of the shoulder joint. Each point indicates the average location of the pointing movement, and error bars indicate the variability (standard deviation) across subjects. B. Movement vector angle (MV). The graph gives the angle between the movement vector and the horizontal line. Negative and positive values correspond to downward and upward movements, respectively. C. signed Index of Path Curvature: The graph depicts sIPC values for every initial posture. Positive and negative values correspond to globally concave and convex paths, respectively. D. Joint coupling. values are reported. Low values indicate low level of correlation between the shoulder and elbow angular displacements. E. Amplitudes of angular displacements. The graphs correspond to the shoulder (left) and elbow (right) joints, respectively. The magnitude of joint displacements (in degrees) is given for all initial postures.