Author(s)

Hiroshi R. Yamasaki, Urara Nakamura, Hiroshi Nagasaki

Department of Health and Welfare, Tohoku Bunka Gakuen University, Sendai, Japan.
Department of Physical Therapy, Showa University, Yokohama, Japan.

The purpose of this study was to examine the hypothesis that the minimum angle-jerk with via-point model could account for the temporal consistency of kinematics in sit-to-stand (STS) and back-to-sit (BTS) movements. The positions of bony landmarks on the subjects during the tasks were recorded using a Vicon motion analysis system to yield the angular displacement and position of the center of mass (COM) of a three-link rigid body model in the sagittal plane. Minimum angle-jerk and minimum jerk trajectories with a via-point were computed for joint angle and COM, respectively. Five to six candidate points were selected as the via-point from the measured trajectory based on the separate kinematic events. The results show the optimal angular trajectories using the via-points (via-angles) before the seat-off for STS, and at around the seat-contact for BTS resembles the measured angular trajectories well, indicating that the posture at the via-point was temporally optimal to produce the minimum angle-jerk trajectory for both movements. It is hypothesized that the multi-joint angular patterns during STS and BTS movements were organized to pass through the via-point, namely the via-posture along the minimum angle-jerk trajectory.

Temporal Optimality, Via-Posture, Trajectory, Sit-to-Stand, Back-to-Sit

Yamasaki, H. , Nakamura, U. and Nagasaki, H. (2014) Temporal Optimality of a Via-Posture on Trajectory during Sit-to-Stand and Back-to-Sit Movements. Journal of Biomedical Science and Engineering, 7, 387-396. doi: 10.4236/jbise.2014.77041.