389 / 2022-01-31 13:30:47

Reliability of standing model and identification technique in response to support surface perturbation

Center of Mass; Standing balance; System identification; Intraclass correlation; Force sensor

Special Sessions > Human Vibration and Health Sensor Applications

Many past studies have modeled a standing balance system for the support surface perturbation. However, the unique and stable identification for individual models is difficult due to the low reproducibility of the response. To achieve it, the assumed model needs to be simple and close to the mechanical properties. In addition, to make a practical identification method, it is desirable to simplify the measuring method of the center of mass(CoM). This study aims to develop an identification method of standing response to the support surface perturbation on the sagittal plane. The response, the CoM of the body, is estimated from the measurements of the force sensors under both feet instead of the motion capture system. The model was based on a single inverted pendulum model assuming the ankle joint strategy, and the passive response to unexpected perturbation was analyzed. We assumed a state-delayed feedback system (inner-loop) and the reference position of the CoM in proportion to the support surface velocity (outer-loop). Thirty healthy male subjects were tested to validate the method, and all subjects identified stable systems. The reliability of the identified system was evaluated using the intra-class correlation coefficient (ICC). The results demonstrated that the same parameters could be determined using force sensors without using the motion capture system. Comparing the identification results of three sets of experiments, the ICC of the inner-loop parameters was over 0.8. This method may contribute to developing standing simulation models and assessing standing balance.