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 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.展开更多
This paper presents a new study on modeling and optimization of trajectory and posture for the super-giant(SG)slalom of alpine skiing.It is the first time that a Three-Rigid-Body-Particle model based on rigorous deriv...This paper presents a new study on modeling and optimization of trajectory and posture for the super-giant(SG)slalom of alpine skiing.It is the first time that a Three-Rigid-Body-Particle model based on rigorous derivations and stability analysis is established to represent skiers trajectory and posture characteristics,as it is more accurate than the single-rigid-body model which is commonly used in existing studies.In addition,the Radau pseudospectral method is applied to solve the trajectory and posture optimization problem in order to obtain better skiing trajectory,skiing posture,and some key kinematic parameters of skiers.Moreover,this paper analyzes the effects of different body types,minimum turning radii,and flexor and extensor strength of knees and hip joint on skiing performance.Finally,based on the findings of the study,some advice about how to improve the performance of the SG slalom in view of science and technology is given to skiers and coaches for reference.展开更多
文摘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.
基金supported in part by the Key Technology Research and Demonstration of National Scientific Training Base Construction of China under Grant No.2018YFF0300800in part by the National Natural Science Foundation of China under Grant No.62173323in part by Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘This paper presents a new study on modeling and optimization of trajectory and posture for the super-giant(SG)slalom of alpine skiing.It is the first time that a Three-Rigid-Body-Particle model based on rigorous derivations and stability analysis is established to represent skiers trajectory and posture characteristics,as it is more accurate than the single-rigid-body model which is commonly used in existing studies.In addition,the Radau pseudospectral method is applied to solve the trajectory and posture optimization problem in order to obtain better skiing trajectory,skiing posture,and some key kinematic parameters of skiers.Moreover,this paper analyzes the effects of different body types,minimum turning radii,and flexor and extensor strength of knees and hip joint on skiing performance.Finally,based on the findings of the study,some advice about how to improve the performance of the SG slalom in view of science and technology is given to skiers and coaches for reference.
