Position Of COG Research Articles

Human Motion Capture System Based 3D Reconstruction on Rehabilitation Assistance Stability of Lower Limb Exoskeleton Robot Climbing Upstairs Posture

Stair-climbing posture is a common motion posture of lower extremity exoskeleton robots. In the process of climbing stairs, with the change of the gravity center of system, it has a direct impact on the dynamic stability characteristics of human-machine system. Based on this, a complete diagram of the stair-climbing posture can be set up, which can be divided into the starting stage, the intermediate stage and the ending stage. The foot trajectory, COG trajectory and ZMP trajectory of human-machine system in the intermediate stage of stair-climbing posture can be analyzed by drawing stair-climbing motion diagram of six-step. Based on the inverted pendulum theory, a virtual inverted pendulum model with variable height (VCHIPM) is proposed to analyze the influence of the change of the gravity center on the dynamic stability of the human-machine system in the upstairs posture. The test results show us that COG position can be changed by adjusting the value of a, so as to adjust the position of ZMP, reduce the error of ZMP and ensure the stability of human-machine system.

Parameter estimation of COG Jacobian for drone with arm capable of adjusting its COG position

To realize aerial manipulation using a drone, it is required to control the position of the center of gravity. In order to fly safely, it is necessary to obtain the parameters used for the control before takeoff. However, it is not easy to determine the parameters in advance due to changes in parts or batteries or changes in the objects to be transported. Therefore, in this research, we propose a method to estimate these parameters before flight and show its effectiveness by experiment.

Relationship of Cervical Sagittal Vertical Alignment After Sagittal Balance Correction in Adult Spinal Deformity: A Retrospective Radiographic Study.

Retrospective radiographic study. Predict the variability of the center of gravity of head (COG) relative to the global cervical sagittal alignment (SVA). Cervical lordosis, thoracic kyphosis, lumbar lordosis, and pelvic incidence are considered interrelated, with changes in SVA causing reciprocal changes to bring the head over pelvis. The implications of cervical deformities have generated more interest recently, and it has been shown that poor cervical alignment is associated with poor clinical outcomes. Patients were selected from the imaging server of a single institution with adult spinal deformity (ASD) and SVA, who underwent surgical correction from 2008 to 2013. Three observers performed the measurements, and intraclass correlation coefficient (ICC) was measured for inter and intraobserver reliability. Group 1 was patients with unbalanced spines (C7-SVA > 5 cm) preoperatively and corrected to full balanced spine (C7-SVA < 5 cm) until last follow-up. Group 2 was improved in sagittal balance after surgery and maintained SVA correction until last follow-up, but not fully balanced. Fifty-five patients met the inclusion criteria, 42 patients improved in SVA after surgery, and 13 showed no improvement. Twenty-three patients kept full balanced measurements until last follow-up, and 19 patients maintained not-full balanced spine. In group 1, there was no change in pre and postoperative parameters except for C2-CL (21.74° vs 16.91°, P = .033). It was similar in group 2, no differences except for C2-CL (21.67° vs 17.81°, P = .018). Parameters in this study failed to yield predictable relationships when compared to changes in SVA. The position of COG may be independent of global SVA. This study aims to improve our understanding of the dynamic changes and relationships of the regional and global spinal parameters with regard to spinal deformity corrective surgeries in adults. III.

起立・着座支援システム使用者の重心候補推定

We propose a method to estimate CoG candidates for standing/sitting support system user. In order to provide appropriate support, real-time estimation of user's state have been studied by many researchers. It is also important to acquire data of user's state in various motion for evaluation of user's health. Measuring human state precisely is difficult, so state estimation method using several user's information have been studied. Position of CoG is useful to human state estimation. However, precise calculation of CoG requires large amount of sensors or expensive measurement system. Therefore we consider how to estimate it using a few inexpensive and simple sensors. In this article, we propose a method to calculate the candidates of human CoG. We validate the proposed method by experiment using motion capture system and sensors which are actually placed prototype of assistive robot.

空中変形可能な多節型飛行ロボットにおける複数物体把持運搬のための形状最適化制御

In this paper, we show the achievement of multiple objects transportation by a transformable aerial robot. As it is not easy to make the flight endurance of an aerial robot longer, we study the problem to transport multiple objects at the same time to improve the efficiency of transportation. However, for conventional aerial robots, multiple objects transportation is difficult because the CoG position changes when the number of grasped objects changes, resulting in the instability of the flight. Therefore, to solve this problem, we focus on the multirotor with two-dimensional multilinks proposed in our previous work, which possesses the ability to modify the CoG position actively and can keep the flight stable. We then propose a method to find the optimal form for the multilinks based on the flight stability. Finally, we present the experimental result of multiple objects transportation.

杖型歩行支援ロボットのための重心位置推定手法

杖型歩行支援ロボットのための重心位置推定手法

Evaluation of falling risk during rising movement with focusing COG position and velocity

Evaluation of falling risk during rising movement with focusing COG position and velocity

Neuropathological approach to conservative treatment of scoliosis- a theoretical view point

Passive keeping the vertical layout is impossible because of the osteoarticular system construction, a high position of COG and the small support area. The correct layout is maintained automatically and is always introduced into the pattern encoded in the CNS. In posture regulation short back muscles play a special role. At early development of scoliosis CNS automatically corrects irregularities, but over time habituated to them and treats them as something normal. Then we have a habit of incorrect body posture. Any attempt to restore the proper body arrangement is treated as an error and CNS automatically brings an attitude to this abnormal pattern. Later CNS treats it as a defect, which runs the compensatory mechanisms to restore the balance of the body as a whole. Then we have postural alignment, which provides a balance, but does not restore the proper body arrangement. In the scoliosis treatment it is important to slow progression and prevent the formation of muscle imbalances and to develop the abnormal habit, which are essential part of a vicious circle, even without progression. Depending on the angle of curvature, observation, corsets and surgical treatment are recommended. A passive observation limits the possibilities of secondary prevention and interfere with the principle of rehabilitation earliness. In conservative treatment physical therapy methods are treated as unconventional treatment, questioning its effectiveness. There is no evidences that physiotherapy is not good and the sole means of secondary prevention. The biggest problem is transfer the resulting of correction for automatically adjusted corrected vertical posture [1-8].

Center of Gravity Compensation for Dynamically-Balanced Two-Wheeled Wheelchair System

Two-wheeled systems have many advantages compared to statically stable systems. This paper describes a control strategy of dynamically-balanced two-wheeled wheelchair system that does not have any front casters. In this system, rider can sit the seat and control the motion of the system by adjusting CoG of his/her body. Unlike other commercial two-wheeled systems, CoG position of the upper body is mainly determined by the position of the user. Thus, there is a possibility that CoG position may not overlap with the wheel axis. In that case, sensor information cannot be used to measure the exact position of the CoG. This paper shows an estimation of method of the unknown CoG position for Two-Wheeled Dynamically-Balanced Wheelchair (TWDBW) is considered. Gravity torque observer with a compliance control is utilized to realize stable compensation according to the variable CoG position. Backstepping based nonlinear control design is applied to regulate and track the CoG motion of the upper body in the TWDBW. The validity of proposed method is verified by simulation and experimental results.

A23 左右方向への移動における反応時間と左右重心位置との関連性(生体負荷)

The purpose of this study was to examine the relationship between the position of COG and response time on 3 experiment conditions setting right, center and left position of COG with flexing 60 degree angle at hip and knee joint. Six subjects kept the assigned posture on a forceplate until LED signal. After the signal, each subject moved to left or right as quickly as possible. RESPONCE TIME was defined as the interval time from the LEDsignal to kick-foot off (kick-foot was the opposite leg from movement direction). MOVEMENT TIME was defined as the interval time from the LED signal to the time that COG shifted 40% of height form the midpoint of initial second metatarsal in the lateral direction. In the result, MOVEMENTTIME were shortened on condition that COG shifted the position for movement direction.

239 2足歩行機構の受動能動融合型歩行

In our study, we aims at the realization of a passive/active unified dynamic walking with walking efficiency and environmental adapting ability. In this paper, we treat a 4-link bipe robot as a study object and performed walking analysis based on the passive/active unified actuator developed until now. First, in order to synchronize rolling motion and the walking cycle in a Frontal surface, rolling motion was analyzed and the foot arc radius and the COG position were designed. Next, walking analysis of the 4-link biped robot with added mass and passivity and passive/active unified actuator in the Sagittal surface was carried out, and the stable walking was shown.

평행봉 Tichonkich 동작의 운동학적 분석

The purpose of this study is helps to make full use for perfect performance by grasping the defects of Tichonkich motion performed by athlete CSM For this, the study analyzed kinematical variables through Tichonkich motions performed at the first selection competition(1st trial) and final selection competition(2nd trial) for the dispatch to the 28th Athens Olympic Games using the three-dimensional cinematographical method with a high-speed video camera, and obtained the following results. 1. During Tichonkich motion, the execution time of up swing and the right hand moving to the left bar was shorter in the 2nd trial than the 1st one, while the execution time of down swing, the support of the left bar and the right hand moving to the right bar was longer in the 2nd trial than the 1st trial. 2. The horizontal position of COG in the 2nd trial was -35cm in the 1st stage, 42cm in the 3rd stage and 29cm in the 4th stage, that is, it showed a great swing focused on the circular movement compared to the 1st trial, while the vertical position of COG was -59cm in the 2nd stage, that is, it showed a small swing focused on a up and down movement. Also the 5th stage vertical position was 98cm, and the 6th stage vertical position was 95cm in the 2nd trial which were higher than those of the 1st trial, so it has provided magnificence required in the modern gymnastics. 3. And it was indicated that the horizontal velocity at the down swing phase proceeded forward more rapidly in the 2nd trial than that in the 1st trial, and the reverse ascent made a rapid vertical rise lessening left and right velocity change. And in the 5th stage, the 2nd trial was kept very slower in horizontal, vertical and left and right velocity that in the 1st trial, so it reached a handstand with leisurely movement. 4. In the 2nd trial, shoulder joint of the 1st, 2nd, 3rd stages kept a larger angle than that in the 1st trial, that is, it made a great swing while in the 1st trial, it showed a swing movement dependent on kick movement by the flexion and extension of hip joint. Also in the 2nd trial, the body formed a vertical posture with both hands supporting the left bar and hip joint was kept larger as and in the 5th and 6th stage than that in the 1st trial, so it made a handstand with the body uprightly stretched out, and magnificent and stable movement.

볼링 스윙동작시 신체중심과 볼 이동궤도의 편차에 관한 연구

The purpose of this study was to compare between success and failure in bowling throw motions. For the data analysis, it was utilized by the method of three dimensional motion analysis and obtained kinematical parameters of stride, COG position, ball position and relative position of ball toward the C.O.G through the address and release motion. The subjects of this study were three female bowling players, and obtained conclusions were as follows; Displacements of stride were not significance of success events, 4th and 5th phase stride were longer than failure. COG variation for height were less than failure, but there were not significance between success and failure. The ball position of 3 th phase was lowest than other phases, and throw motions were stable by the small variations for upward and downward. Success events of Relative positions of ball were more regulated than failure in whole swing phases.

脚の振り降ろしを利用した起き上がり運動における角運動量条件

In this paper, we consider a stand-up motion from a face-up lying posture by means of swing-down movement of a leg. Because whether the motion is feasible or not depends on the angular velocity of the leg swing, we propose a method to calculate it approximately. This calculation is based on the phase plane analysis and on conservation of angular momentum. The main problem there is how to evaluate the motion during the rotation around hip, where angular momentum has an effect of the gravity. Here, we calculate it using the initial and final position of COG in the hip rotation phase. This method enables us to estimate a necessary angular velocity without solving dynamic equation. Finally, we examine the effectiveness of the method by simulation and experiments with our constructed robot.

볼링의 투구동작에 대한 운동학적 분석

본 연구는 볼링 투구동작의 성패는 스텝과 스윙이 결정한다는 가정 하에 어프로치에서의 동작에 주안점을 두고, 볼링선수를 대상으로 자유로이 투구를 하게 하고 피험자 본인이 잘되었다고 판단하는 동작과 잘못되었다고 판단하는 투구 동작을 비교 분석하는 것이 본 연구의 목적이다. 투구동작시 어드레스에서부터 릴리즈까지의 동작을 각 스텝별로 국면을 설정하고, 3차원영상분석을 실시하여 각 스텝별로 보폭, 신체중심의 위치, 볼의 위치를 성공과 실패동작으로 나누어서 비교 분석하였다. 보폭은 성공과 실패동작에서 큰 차이를 보이지 않았으며, 4국면과 5국면에서의 보폭이 실패동작에서 크게 나타났다. 신체중심의 위치에서도 큰 차이를 보이지 않았으나 성공시가 실패시보다 상하 이동폭이 작게 나타났다. 볼의 위치는 성공과 실패시 모두 스텝중에는 3국면이 가장 낮게 나타났으며, 상하 이동폭이 적은 안정적인 투구를 하는 것으로 나타났다. The purpose of this study was to compare between success and failure in bowling throw motions. For the data analysis, it was utilized by the method of three dimensional motion analysis and obtained kinematical parameters of stride, COG position and ball position through the address and release motion. The subjects of this study were three female bowling players, and obtained conclusions were as follows; Displacements of stride were not significance of success events, 4th and 5th phase stride were longer than failure. COG variation for height were less than failure, but there not significance between success and failure. The ball position of 3 th phase was lowest than other phases, and throw motions were stable by the small variations for upward downward.

A spot check to ensure the quality of matching of kinematic and kinetic data collected during clinical gait analysis

gait this pattern is believed to be due to a dynamic dysbalance of hip flexors and hip extensors. In contrast to a so called ‘single bump’ pattern in hemiplegic gait the identification of a muscles contribution to a ‘double bump’ pattern is difficult because both sides are affected and multi joint muscles are involved. Although the ‘double bump’ is easy to identify by the use of gait analysis the clinical decision making upon the dysbalance depends mostly on static clinical tests. Reduced extension of the hip in terminal stance can be interpreted as a sign of contracture of the M. psoas major. As the hip joint motion in the sagittal plane is easily quantifiable by gait analysis one may take an extension deficit of the hip as a valid parameters for a hip flexor pathology. As trunk position (COG position) sets certain requirements for the range of hip movement it is essential to monitor trunk segment kinematics. Therefore, an extension deficit at the hip joint requires consideration of the trunk position additionally to the influence of multi joint muscles. A forefoot landing presented by a diplegic patient often raises interest in the activation behaviour of the M. triceps surae under dynamic conditions. Spastic muscle behaviour could be identified through qualitative evaluation of high angle accelerations, power absorption-generation patterns or through a sharp increase in high power EMG signals during loading response but by now we know of no valid parameter to quantify muscle activation behaviour in spastic diplegic gait.