Motomichi Sonobe

Noninvasive Estimation of Lumber Disk Load During Motion to Improve the Posture

In order to reduce the load by improving the posture, it is necessary to know the load to the lumbar intervertebral disk when patients are in various motions. In this study, we propose a method to noninvasively estimate the load of the lumbar disc during motion. In the proposed method, we consider that the change in the gap between the vertebrae due to the posture change is determined only by the deformation of the intervertebral disc. And the internal changes are estimated indirectly by measuring the shape of the lumbar part from outside the body. And the deformation of the disc is estimated with this, and it will be evaluated as an intervertebral disc load. In this study, a disc load of sneezing motion was estimated and the load on lumber intervertebral disk during motion could be estimated with the proposed method.

Estimation of Hip Joint Moment by an Inertial Measurement Unit

This research is to estimate the hip joint moment without using a force plate that disturbs the gate. The purpose of this research is to show that with a single leg supporting period, the system is statically fixed, making it possible to derive the hip joint moment from the balance of inertial force and gravity without a force plate. Therefore, in this research, a wearable inertial measurement unit was used to measure the acceleration and angle of five body parts, and the hip joint moment was estimated. The proposed method, which estimated the hip joint moment using the inertial measurement unit, and the conventional method which estimated the hip joint moment using the information of the force plate showed similar results. Thus, the validity of the proposed method was obtained.

Noninvasive Estimation of Lumbar Intervertebral Disk Load Using Multiple Regression Analysis to Consider the Pelvic Tilt

In this study, a noninvasive method to estimate the load on the lumbar disk is proposed. By using the proposed method to evaluate posture, a system that user himself improves bad posture is provided. The load applied to the lumbar is indirectly estimated from the moment about the lumbar vertebra. Assuming the lumbar vertebrae part as a beam, it should consider three elements, the weight of the upper body, the weight of the heavy objects, and the bending of the lumbar part due to the pelvic tilt. In order to examine the validity of this proposal, multiple regression analysis by a simple model was carried out. As results, the tendencies of the proposed method were qualitatively consistent to the tendencies of the conventional method.

Experimental Elucidation on Balance Mechanism in Golf Swing for Performance Improvement

In the golf swing, the inertial force acts on the player by the movement of the arm and the club during the swing. If player do not take any countermeasures, player will not be able to get balanced and will stagger. So, we conducted an experimental study to clarify what kind of action balances the players in order to stagger. Swing motion and floor reaction force were measured using a three dimensional motion analysis device and a force plate. From the results, we estimated the inertial force caused by the swing and the inertial force due to the other movements separately from the ball hitting direction and the anterior-posterior direction. We clarified how each inertial force affects the trajectory of the center of pressure.

Estimation of Floor Reaction Force During Walking Using Physical Inertial Force by Wireless Motion Sensor

Floor reaction force is widely used to evaluate walking. Generally, floor reaction force is measured by a floor reaction meter. However, floor reaction meter is not suitable for clinical practice due to the limitation in walk condition, measurement range and device size. This study suggests a simple method to estimate floor reaction force by processing dynamic acceleration information to be provided from small wireless motion sensors. In the experiment, optical motion capture and the floor reaction meter were used. The result shows that the sum of the inertial force of the whole body and gravity equal floor reaction force obtained through an experiment using optical motion capture. We consider that physical inertial force of the whole body could be estimated from the dynamic acceleration of the lower trunk and right/left thighs. A similar result obtained with the motion sensor. An estimation of floor reaction force by measuring the inertial force is effective, and much simpler walk analysis could be possible with using appropriate signal handling of wireless motion sensor information. This method can be applied to biofeedback.

Frontal Plane Modelling of Human Dynamics during Standing in Narrow-Stance

Standing ride type vehicles like electric skateboards have been developed in recent years. Although these vehicles have advantages as being compact and low cost due to their simple structure, it is necessary to improve the riding quality. Therefore, the system aiding riders to keep their balance on a skateboard by feedback control or feedforward control has been required. To achieve it, a human balance model should be built as simple as possible. In this study, we focus on the human balance modelling during standing when the support surface moves largely. We restricted the model on frontal plane and narrow stance because the restrictions allow us to assume single-degree-of-freedom model. The balance control system is generally assumed as a delayed feedback control system. The model was identified through impulse response test and frequency response test. As a result, we found the phase between acceleration of the skateboard and posture angle become opposite phase in low frequency range.