九州大学 研究者情報
発表一覧
AN QI(あん ち) データ更新日:2021.06.18

准教授 /  システム情報科学研究院 情報知能工学部門


学会発表等
1. Qi An, Hiroshi Yamakawa, Atsushi Yamashita and Hajime Asama, Temporal Structure of Muscle Synergy of Human Stepping Leg During Sit-to-Walk Motion, 14th International Conference on Autonomous Intelligent Systems (IAS-14), 2016.07.
2. Ruoxi Wang, Qi An, Ningjia Yang, Hiroki Kogami, Kazunori Yoshida, Hiroyuki Hamada, Shingo Shimoda, Hiroshi Yamasaki, Moeka Sonoo, Fady Alnajjar, Noriaki Hattori, Kouji Takahashi, Takanori Fujii, Hironori Otomune, Ichiro Miyai, Atsushi Yamashita and Hajime Asama, Muscle Tension Analysis in Stroke Patient Sit-to-Stand Motion by Joint Torque-Based Normalization, 5th International Conference on NeuroRehabilitation (ICNR2020), 2020.11, Stroke patients exhibit distinct muscle activation features in sit-to-stand motion due to motor deficiency. Muscle activation amplitude is an important feature but has not been clarified due to the lack of a valid normalization method to enable intra-subject comparisons. This study, focusing on the paretic side, examines the change in muscle tension manifested in activation amplitude for a stroke patient in serial measurements by a novel method based on joint torques.We constructed a musculoskeletal model, calculated joint torques by inverse dynamics, and solved muscle activation by forward dynamics simulation. Results showed that tibialis anterior, gastrocnemius, vastus lateralis, rectus abdominis, and erector spinae muscles on the paretic side showed significant improvement in generating maximum muscle tension after a rehabilitation training for 120 days..
3. Kei Aoyagi, Wen Wen, Qi An, Shunsuke Hamasaki, Hiroshi Yamakawa, Yusuke Tamura, Atsushi Yamashita, Hajime Asama, Improvement of Sense of Agency during Upper-Limb Movement for Motor Rehabilitation Using Virtual Reality, 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2019, 2019.07, [URL], Sense of agency refers to the feeling of controlling one's own body. Many patients surviving from a stroke lose the sense of agency over their body. This is due to impairments in both motor control and sensory brain functions. As a result of this lack in the sense of agency, stroke patients tend to lose the intention of moving the paralyzed limb, which results in further deterioration of brain functions and worsening muscles and joints. The present study proposes a motor rehabilitation system using virtual reality to improve the sense of agency during upper-limb movement which is required for various daily life activities such as eating meals and operating devices. Specifically, participants were instructed to move their hand to track a moving target ball in a virtual reality environment, while the position of their real hand was measured via a motion capture system. Participants were shown another ball presenting the position of their hand in virtual reality. We tested the proposed system with healthy participants, of which the motor control was disturbed by a 1-kg weight attached on the wrist. Participants reported their sense of agency after each trial. The results showed that the sense of agency was enhanced by the proposed intervention. Our results pointed out a potentially useful method to improve the sense of agency during body movements using modified visual feedback, which may contribute to the development of rehabilitation for stroke patients..
4. Sonmin Yun, Wen Wen, Qi An, Shunsuke Hamasaki, Hiroshi Yamakawa, Yusuke Tamura, Atsushi Yamashita, Hajime Asama, Investigating the relationship between driver's sense of agency and EEG
Mu-rhythm is more suppressed in higher SoA case, 28th International Symposium on Micro-NanoMechatronics and Human Science, MHS 2017, 2018.02, [URL], In recent years, the field of automated driving has made a great progress. Especially, driver assistance and partial automation has been made practicable rapidly. While it is expected to reduce the number of traffic accidents, the assisted driver may feel less control over the vehicle. In other words, they may lose a sense of agency over the vehicle. Sense of agency (SoA) refers to the subjective feeling of controlling events through one's own behavior. It is reported that under less SoA conditions, one's response to an event becomes slower [1]. It can be suggested that poor SoA of driver may result in slow and inaccurate response in emergency cases. Therefore, it is important to maintain the driver's SoA during the assisted driving. For example, if the driving assist system could monitor the driver's SoA, it can give appropriate feedback when the SoA decreased..
5. N. Yang, Q. An, H. Yamakawa, Y. Tamura, A. Yamashita, K. Takahashi, M. Kinomoto, H. Yamasaki, M. Itkonen, F. S. Alnajjar, S. Shimoda, H. Asama, N. Hattori, I. Miyai, Clarification of muscle synergy structure during standing-up motion of healthy young, elderly and post-stroke patients, 2017 International Conference on Rehabilitation Robotics, ICORR 2017, 2017.08, [URL], Standing-up motion is an important daily activity. It has been known that elderly and post-stroke patients have difficulty in performing standing-up motion. The standing-up motion is retrained by therapists to maximize independence of the elderly and post-stroke patients, but it is not clear how the elderly and post-stroke patients control their redundant muscles to achieve standing-up motion. This study employed the concept of muscle synergy to analyze how healthy young adults, healthy elderly people and post-stroke patients control their muscles. Experimental result verified that four muscle synergies can represent human standing-up motion. In addition, it indicated that the post-stroke patients shift the weights of muscle synergies to finish standing-up motion comparing to healthy subjects. Moreover, different muscle synergy structures were associated with the CoM and joint kinematics..
6. Rin Minohara, Wen Wen, Shunsuke Hamasaki, Takaki Maeda, Qi An, Yusuke Tamura, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, How anticipation for the sense of agency affects readiness potential, 27th International Symposium on Micro-NanoMechatronics and Human Science, MHS 2016, 2017.01, [URL], In recent Japanese society, we are facing a severe increase in the number of patients who suffer from motor paralysis and other dysfunctions. Establishing an effective rehabilitation system for them is important, and the key to attain this target is to clarify the mechanisms of one's body perception in the brain. The feeling of controlling our action and external event is an important aspect of body perception, and thus is a topic we have to investigate. This feeling is called the Sense of Agency (SoA), and in order to clarify the mechanism of the SoA, it is necessary to clarify neuro-physiological indices that reflect the arising of this feeling. Recent investigated the relationship between SoA and neural activity with event-related potential (ERP) but these studies focused only on the feedback processing after the action-feedback (e.g. N100, P300), while no study investigated the neural basis of the action-preceding part during SoA paradigm. In this research we focused on feedback-anticipation as an action-preceding factor of SoA, and the purpose of this research is to find a neuro-physiological indices which reflect this factor. We hypothesized that readiness potential (RP) would reflect this factor. In the Libet's clock task based experiment, two conditions which differed in the state of the anticipations for the feedback were prepared. In order to manipulate the anticipation, the probability of the tone occurrence was manipulated in each condition. Earlier and larger RP was observed when the feedback-anticipation was inconsistent in relative with the consistent condition, and additional experiment by increasing the sample size is needed. Our study is the first one that reveals the neural basis of the action-preceding factor of SoA, and we believe that our study will contribute to unravel the neural basis of the SoA..
7. Qi An, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Temporal structure of muscle synergy of human stepping leg during sit-to-walk motion, 14th International Conference on Intelligent Autonomous Systems, IAS 2016, 2017.01, [URL], In daily lives, humans successfully transit their motions rather than performing separate movements. It has been widely acknowledged that there are four and five modules (called muscle synergy) in human sit-to-stand and walking motions, but it was still unclear how humans activate their redundant muscles to transit their movement from sitting to walking. Therefore this study hypothesize that human sit-to-stand can be explained from muscle synergies of sit-to-stand and walking motions, and we perform the experiment to verify it. Firstly, four and five muscle synergies were obtained from sit-to-stand and walking motion, and it has been tested whether these nine synergies are applicable to sit-to-walk motion. Results showed that sit-to-walk motion were successfully explained from nine synergies. Moreover, it was shown that humans adaptively changed the activation time of each synergies to delay body extension time and to generate necessary initial momentum for the walking motion..
8. Arito Yozu, Dai Owaki, Masashi Hamada, Takuya Sasaki, Qi An, Tetsuro Funato, Nobuhiko Haga, Quantification of temporal parameters for tripedalism, 14th International Conference on Intelligent Autonomous Systems, IAS 2016, 2017, [URL], Bipedalism is one of the distinctive features of humans. However, humans in certain conditions use tripedalism for their locomotion. Patients who cannot bear their weight on their own legs or patients with balance disorders often use a cane. Temporal parameters have been defined for bipedalism, while they have not been defined for tripedalism. Therefore, in clinical rehabilitation, evaluation of patients’ gait using a cane is still very much a qualitative issue. In this study, we propose how we can define the temporal parameters for tripedalism. We calculated six quantitative numbers: (1) gait cycle of leg 1, (2) lag of foot strike between leg 1 and leg 2, (3) lag of foot strike between leg 1 and leg 3, (4) stance phase of leg 1, (5) stance phase of leg 2, and (6) stance phase of leg 3. With a set of these six elements, the foot strike and foot-off pattern of the three legs is uniquely determined. Because these elements are measurable quantitatively, we are able to express the tripedal gait in a quantitative manner with this number set. We call this number set “gait matrix”. The application of this gait matrix may be useful for evaluating patients’ gait using a cane in rehabilitation..
9. Daisuke Tomoi, Wen Wen, Hiroshi Yamakawa, Shunsuke Hamasaki, Kaoru Takakusaki, Qi An, Yusuke Tamura, Atsushi Yamashita, Hajime Asama, Estimation of stress during car race with factor analysis, International Symposium on Micro-NanoMechatronics and Human Science, MHS 2015, 2016.03, [URL], Car race drivers are always in dangerous and harsh environments. In order to reduce risks due to mental stress, it is important to evaluate stress during a car race in real-time. The present study measured three physiological indices, heart rate variability, sweat rate, and electromyogram of massester from a professional racer during a car race. However, the relation between these indices, and the types of stress still remains unclear. In the present study, we examined the relations between the three indices and factors linked with these indices during car race with factor analysis. The results suggested that the three physiological indices related to two different factors. One factor scored high when driver saw other nearby car, and was influenced mainly by heart rate variability and sweat rate. We suggest that mental stress is probably high in such scenes, and named this factor as mental stress. Furthermore, the other factor showed high values during urgent accelerations and decelerations, and was influenced mainly by electromyogram of massester. During urgent accelerations and decelerations, the driver probably suffered from large physical discomfort. Therefore, we named the second factor as physical stress. In summary, we found the three physiological indices reflected two different types of stress during car race. Moreover, according to the results of factor analysis, we proposed a method of real-time estimation of both mental and physical stress with the three physiological indices during car race..
10. Shunsuke Hamasaki, Qi An, Wen Wen, Yusuke Tamura, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Satoshi Shibuya, Yukari Ohki, Evaluating effect of sense of ownership and sense of agency on body representation change of human upper limb, International Symposium on Micro-NanoMechatronics and Human Science, MHS 2015, 2016.03, [URL], To improve rehabilitation of the diseases which are caused by the mismatch between real body and body representation, it is necessary to understand the mechanism of body representation change. It is assumed that sense of agency and sense of ownership are closely-related with body representation and influence body representation change of the body parts without visual information. We focused on human upper limb and performed experiment with participants on four condition related to sensitivity of agency and ownership. We measure perceived position change of elbow and finger by pointing judgement using motion capture. Visual stimulation which participants given is only virtual hand. Our experiment has revealed that sense of agency influence the body representation change on the body parts which is invisible to participants..
11. Qi An, Yuki Ishikawa, Tetsuro Funato, Shinya Aoi, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Muscle synergy analysis of human standing-up motion using forward dynamic simulation with four body segment model, 12th International Symposium on Distributed Autonomous Robotic Systems, DARS 2014, 2016.01, [URL], Human motor behavior can be generated by distributed system. In this study, human standing-up motion is focused as an important daily activity. Especially, 13 muscle activation of lower body and trunk measured during human standing-up motion is decomposed into small numbers of modules of synchronized muscle activation called muscle synergy. Moreover human musculoskeletal model is developed with four rigid body segments based on dynamics and anatomical characteristics of human body. Forward dynamic simulation with the developed model showed that four muscle synergies had their own contribution toward body function: bending forward, moving the center of mass forward, extending whole body, and decelerating the center of mass. Results also indicated that combinations of four modules of synchronized muscle activation could generate human standing-up motion rather than controlling individual muscles..
12. Qi An, Yuki Ishikawa, Shinya Aoi, Tetsuro Funato, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Analysis of muscle synergy contribution on human standing-up motion using a neuro-musculoskeletal model, 2015 IEEE International Conference on Robotics and Automation, ICRA 2015, 2015.06, [URL], It is important to understand the mechanism of human standing-up motion to improve the declined physical ability of the elderly people. This study employs the concept of muscle synergies (modular structure of coordinative muscle activation) to understand how humans coordinate their muscles to achieve the standing-up motion. Neuro-musculoskeletal model was developed to represent human body to generate standing-up motion. Using the developed model, forward dynamic simulation was used to analyze how humans utilized the muscle synergies to realize the motion. Results showed that the developed model could generate the standing-up motion with four muscle synergies rather than controlling individual muscles. Moreover, further analysis showed that three different strategies of the standing-up motion could be generated only by changing the start time of the particular muscle synergy..
13. Qi An, Yuki Ishikawa, Tetsuro Funato, Shinya Aoi, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Generation of human standing-up motion with muscle synergies using forward dynamic simulation, 2014 IEEE International Conference on Robotics and Automation, ICRA 2014, 2014.09, [URL], The standing-up motion is one of the most important activities of daily livings. In order to understand the strategy to achieve the standing-up motion, muscle synergy analysis is applied to the measured data during human standing-up motion. In addition, musculoskeletal model which consists of three body segments and nine muscles in lower limb is developed to ensure that the standing-up motion can be generated by muscle synergies. As a result, three muscle synergies have been extracted from the human standing-up motion, and each synergy strongly corresponded to characteristic kinematic events: momentum flexion, momentum transfer, and posture stabilization. Results of forward dynamic simulation show that the standing-up motion can be achieved by controlling time-varying weighting coefficient of three muscle synergies instead of controlling individual nine muscles..
14. Yuki Ishikawa, Qi An, Yusuke Tamura, Atsushi Yamashita, Hiroyuki Oka, Hajime Asama, Effect of mediolateral knee displacement on ligaments and muscles around knee joint
Quantitative analysis with three-dimensional musculoskeletal ligament knee model, 12th International Conference on Intelligent Autonomous Systems, IAS 2012, 2013.01, [URL], Knee osteoarthritis (OA) becomes a major public issue, but a strategy to prevent the disease has not established yet due to lack of an accurate method to measure an internal motion of the knee of individual patients. Therefore mechanical engineering model and a standard of evaluation of the disease is needed to improve the situation. Currently, there are a few studies to develop the model including allowance of joint movement and ligaments. Thus this study shows the model accuracy by forward dynamics and discusses the result of inverse dynamics of various gait patterns. As a result, it can be confirmed that ligaments are more effective than muscles around knee joint with our various models. In addition we propose the important factor of knee OA from gait pattern and models..
15. Qi An, Yuki Ishikawa, Junki Nakagawa, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Analysis of contribution of muscle synergies on sit-to-stand motion using musculoskeletal model, 2013 IEEE Workshop on Advanced Robotics and Its Social Impacts, ARSO 2013, 2013, [URL], Recently, declining physical ability of elderly people has become an extremely important social issue. To improve their daily living activities, the standing-up motion is emphasized in this study as an important daily motion. Synergy analysis is applied to the standing-up motion to extract four important groups of muscle activations (synergies). Furthermore, the effect of synergies on body movement is calculated based on a musculoskeletal model of the human body. Results suggest that the first synergy works as preparation of the motion by pulling the ankle and flexing the hip. The second synergy controls the joint moment of the hip and knee joints to raise the hip and move the center of mass forward. The third synergy controls the ankle joint according to movement of the center of mass. The last synergy stabilizes the posture change from a seated to a standing position. Our findings imply that it is important to train those functional muscle activity to enhance the ability of standing-up motion..
16. Junki Nakagawa, Qi An, Yuki Ishikawa, Hiroyuki Oka, Kaoru Takakusaki, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Analysis of joint correlation between arm and lower body in dart throwing motion, 2013 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2013, 2013, [URL], As the population continues to age, the number of elderly people requiring healthcare is increasing. In order to improve their physical function, they need to get physical training. There are activities which require integrated arm movements and lower body movements. However there are no quantitative testing methods of the degree of recovery for the coordination between arm movements and lower body movements. In this study, we focus on dart throwing motion as arm movements in lower body movements and suggest the quantitative evaluation of the coordination between arm movements and lower body movements in dart throwing motion. Normalized correlation coefficient (NCC) between arm and lower body was computed at different throwing distances. In addition the standard deviation of the NCC was computed in order to investigate the stability of the joint correlation evaluation. This analysis shows that the correlation between elbow and ankle, or between elbow and knee, are increased at throwing long distance. We suggest that the NCC between elbow angle and right knee angle may be used for the evaluation of the joint correlation between arm movements and lower body movements in dart throwing motion..
17. Qi An, Yuki Ishikawa, Junki Nakagawa, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Muscle synergy analysis of human standing-up motion with different chair heights and different motion speeds, 2013 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2013, 2013, [URL], Although standing-up motion is an important activity of daily living, it remains unclear how people perform the motion in different situations. As described in this paper, muscle synergy analysis is applied to standing-up motions performed at different circumstances, such as two different heights and at three different speeds. Results elucidated three invariant groups of synchronized muscle activations: The first synergy pulls the ankle and raises the hip. The second synergy extends the upper body. The third synergy stabilizes posture. Results also show that people controlled the activation coefficient of each synergy differently during all motions. The slower the standing-up motion is, the longer each synergy activates to adapt to the slower motion speed. Results of this study show that people use the same group of synchronized muscle activation and only control the activation coefficient to achieve adaptive standing-up motion..
18. Qi An, Yusuke Ikemoto, Hajime Asama, Tamio Arai, Analysis of human standing-up motion based on distributed muscle control, 10th International Symposium on Distributed Autonomous Robotic Systems, DARS 2010, 2012.12, [URL], In developed countries, an aging society has become a serious issue; many activities of daily living (ADL) are impaired in the elderly. In order to improve this situation, it is necessary to develop an assisting method for the human standing up motion because it is considered to be an important factor to ADL. It is unclear, however, how humans coordinate their multiple distributed actuators, muscles, due to the ill-posed problem of redundant their body system. In this paper, we analyze the human standing-up motion based on muscle coordinations, called synergies. A simulation method was developed to make mappings between muscle activations, joint torque, and the human body trajectory; thus, it can be predicted how modular muscle coordinations contribute to the motion. As a result, two primary synergies were extracted and how they coordinate to achieve the motion was elucidated; one synergy strongly affected joint movements and speed of the motion while bending the back and lifting the body up, and the other synergy controls their posture after they lift up their body. These findings could be useful for development of an assisting robotic system for rehabilitative training based on extracted distributed synergies from complex redundant human motion..
19. Qi An, Yuki Ishikawa, Junki Nakagawa, Atsushi Kuroda, Hiroyuki Oka, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama, Evaluation of wearable gyroscope and accelerometer sensor (PocketIMU2) during walking and sit-to-stand motions, 2012 21st IEEE International Symposium on Robot and Human Interactive Communication, RO-MAN 2012, 2012.12, [URL], Recently healthcare of the elderly people has become a serious issue in medical and rehabilitation areas. In order to know their functional mobility and provide sufficient medical treatment, it is important to measure their body state precisely and objectively. Therefore we developed a wearable and wireless sensor of gyroscope and accelerometer (PocketIMU2) as an easy and precise measurement of human motions. In the sensor, we employed a small and high accurate LiNbO3 crystal to achieve joint angle computation with simple integration of angular velocity. In the current paper, we evaluate the accuracy of the sensor in two important basic motion, such as a walking and sit-to-stand motions. Computed joint angles of ankle, knee, and hip are compared to the reference data measured from a optical motion capture system in term of coefficients of correlation and root mean square error. As a result, coefficient of correlation showed very high value for all joint angles, and root mean square error was adequately small. This strongly supports the usage of our developed gyroscope and accelerometer sensor for monitoring human body movement for medical usage..
20. Mike Chung, Eric Rombokas, Qi An, Yoky Matsuoka, Jeff Bilmes, Continuous vocalization control of a full-scale assistive robot, 2012 4th IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, BioRob 2012, 2012.10, [URL], We present a physical robotic arm performing real-world tasks using continuous non-verbal vocalizations for control. Vocalization control provides fewer degrees of control freedom than are necessary to directly control complex robotic platforms. To bridge this gap, we evaluated three control methods: direct joint angle control of a selectable subset of joints, inverse kinematics control of the end effector, and control in a reduced-dimensionality synergy space. The synergy method is inspired by neural solutions to biological body redundancy problems. We conducted several evaluations of the three methods involving the real-world tasks of water bottle recycling and grocery bag moving. Users with no prior exposure to the system were able to perform these tasks effectively and were able to learn to be more efficient. This study demonstrates the feasibility of continuous non-verbal vocalizations for control of a full-scale assitive robot in a realistic context..
21. Qi An, Hajime Asama, Yoky Matsuoka, Cara E. Stepp, Effect of vibrotactile feedback on robotic object manipulation, 2012 4th IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, BioRob 2012, 2012, [URL], Recently there have been increased demands to improve function of prosthetic hands. One of the directions is implementation of force feedback to improve object manipulation. Previously we have employed vibrotactile stimulation to safely and non-invasively provide force feedback, showing that participants could improve task performance in a virtual environment. This work used robotic devices to develop a physical experimental environment to replace the previous virtual experimental conditions and to test the efficacy of vibrotactile feedback. Unimpaired participants (N6) were asked to drag a box to a target location. Performance of users was measured based on total box displacement, average box velocity, their subjective difficulty ratings, exerted power, and average applied normal force on the box. With vibrotactile feedback, participants were able to statistically significantly improve their task performance as measured by all parameters except average velocity. This result strongly supports the use of vibrotactile feedback as a simple methodology to provide force feedback to prosthetic hand users..
22. Qi An, Yoky Matsuoka, Cara E. Stepp, Multi-day training with vibrotactile feedback for virtual object manipulation, Rehab Week Zurich 2011 - 2011 IEEE International Conference on Rehabilitation Robotics, ICORR 2011, 2011.11, [URL], Optimal function of prosthetic hands for activities of daily living requires knowledge of contact force; however, users of prosthetic hands must rely on visual feedback for object manipulation, requiring constant concentration. Vibrotactile stimulation was explored as a modality for force feedback over multiple testing sessions. Unimpaired participants (N=6) performed virtual object manipulation with their right index finger using both visual feedback and vibrotactile feedback corresponding to the applied force on the virtual object on four days over a 4-8 day period. Object manipulation outcome measures were user difficulty ratings, object displacement, and object average velocity. Participants were able to utilize the vibrotactile feedback to statistically significantly improve performance of all three outcome measures over the four days. Significant improvements in all outcome measures were seen between days 3 and 4, indicating that steady state performance may not have been reached. Results support the use of augmentative vibrotactile feedback for users of prosthetic hands, though future longer longitudinal study will be necessary to determine steady state performance..
23. Qi An, Hajime Asama, Cara E. Stepp, Yoky Matsuoka, Uncontrolled manifold analysis of standing-up motion for development of an assistance system, Rehab Week Zurich 2011 - 2011 IEEE International Conference on Rehabilitation Robotics, ICORR 2011, 2011.11, [URL], Standing-up motion is essential to performance of the activities of daily life (ADL). In this research, we analyse human standing-up motion in terms of how joint angles coordinate to contribute to the motion. Uncontrolled manifold (UCM) analysis is applied, and degrees of joint coordination are calculated for the entire course of the motion. Those values are investigated for the four phases of the motion to understand which positions of the body are under explicit control. Results indicate that individuals control their hip and shoulder positions in the horizontal direction until extending their upper body and also after they finish lifting up their body. On the other hand, it is shown that vertical direction of the hip and shoulder are controlled until the time they bend their back and lift up their hip. Based on time series of calculated joint coordination over the entire standing-up motion, we suggest a new control method for our previously developed force assisting system. The controller allows deviated range of movement during the time points in which healthy participants show less explicit control of their body positions, and requires more consistent trajectories during times when participants show more explicit control..
24. Qi An, Hiroki Matsuoka, Yusuke Ikemoto, Hajime Asama, Extraction of behavior primitives for understanding human standing-up motion, 2009 IEEE International Conference on Mechatronics and Automation, ICMA 2009, 2009.12, [URL], Recently the aging society is very rapid, and it has brought many problems to our society. In order to avoid these difficult situations, we focus on human standing up motion in our research because this motion is so important to our daily life that it is considered meaningful to support the motion. However, the way of human standing up is still unknown because the analysis of human motion is very difficult. Therefore, we develop integrated simulation methods to understanding the motion from human body data, such as muscle activations (EMG) and human joint torques. We carefully analyze human standing up motion based on muscle movements since muscles do move human body. Through our experiments and analysis, two important muscle coordinations (behavior primitives) are found out; one primitive has a function of generating dynamics of the motion by controlling hip, knee, and ankle and the other primitive controls posture of the body with their ankles. These behavior primitives are elucidated to be such an essential factor toward the motion that the way of standing up becomes unstable without them..
25. Qi An, Yusuke Ikemoto, Hajime Asama, Hiroki Matsuoka, Daisuke Chugo, Kaoru Takakusaki, Extraction of behavior primitives in human standing-up motion for development of power assisting machine, 2008 IEEE International Conference on Robotics and Biomimetics, ROBIO 2008, 2009.01, [URL], Recently, many older people have difficulty standing up despite that motion's importance in daily life. Therefore, a machine to support their standing-up motion is needed; yet we still do not know how people control their motor system when they stand up. For that reason, we can not produce such a machine. In this study, we analyze the system of people's standing-up motion using information related to muscle activity. Muscle synergy-coherent activations of groups of muscles are an efficient means to achieve this goal. The results of experiments demonstrate the importance of muscle synergies that exist when people stand up..

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