| Fall is a serious problem especially among old aged people. In order to develop intervention strategies to reduce the risk of fall and to prevent injury, the mechanism of fall needs to be understood. The overall objective of this study was to investigate the kinematics of the human body during gait and a fall due to tripping over an obstacle.In this study, the human body was modeled as a chain linkage system driven by a set of actuators. A direct dynamics algorithm was developed to simulate the swing phase of gait. A robot control algorithm was introduced in the simulation in order to avoid divergence. The gait model was further developed to simulate a fall caused by tripping of the swing limb on an obstacle. At the end of the tripping, all of the actuator moments were assumed to be not in action, thereby simulating a muscle relaxed fall. The trajectories and velocities of the HAT (head, arm and torso) were obtained to represent the motions of the human body. The simulated results were visualized with animation software. In addition, an experiment of muscle relaxed fall due to tripping on an obstacle was performed on a healthy subject. The contact forces between the swing foot and the obstacle were measured with a force platform. The kinematics of the body measured from the experiment was compared with that from the simulation. The experiment was helpful in understanding the mechanism of fall and improving the modeling, even though there are still some limitations both in the experiment and the model. |
