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Volume 45, Issue 1
Displaying 1-9 of 9 articles from this issue
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Paper
Measurement
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Takashi Yamaguchi, Hirotoshi Kashima, Ichiro Sasada2009 Volume 45 Issue 1 Pages 1-10
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSIn this paper, a fast method of estimating the position of a moving object for a magnetic motion capture system is presented. The system uses two quasi-uniform magnetic fields along the X-axis and the Z-axis and one gradient magnetic field having a null point at the origin. Each of these magnetic fields is produced sequentially by using two pairs of square coils wound along four edges of a cube where one pair is rotated through 90 degree from the other. A triaxial magnetometer is attached to the moving object to measure these magnetic field vectors. The position of the object is calculated from three scalar products among the measured magnetic field vectors. The calculation is done approximately by using a set of truncated Taylor serieses, where Wynn's vector epsilon-algorithm is used together to expand the area of convergence numerically. This method of calculation contains no iterative process and is much faster than the Gauss-Newton method. The position of the object is stably estimated by this method within a cubic area having an edge length of 60 percent of the side length of the coils. A prototype system using a triaxial Hall magnetometer was build. The experimental results show that the method works properly in a real system.View full abstractDownload PDF (1000K) -
Yosuke Kurihara, Kajiro Watanabe, Kazuyuki Kobayashi, Tanaka Tanaka2009 Volume 45 Issue 1 Pages 11-17
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSSleep disorders disturb the recovery from mental and physical fatigues, one of the functions of the sleep. The majority of those who with the disorders are suffering from Sleep Apnea Syndrome (SAS). Continuous Hypoxia during sleep due to SAS cause Circulatory Disturbances, such as hypertension and ischemic heart disease, and Malfunction of Autonomic Nervous System, and other severe complications, often times bringing the suffers to death. In order to prevent these from happening, it is important to detect the SAS in its early stage by monitoring the daily respirations during sleep, and to provide appropriate treatments at medical institutions. In this paper, the Pneumatic Method to detect the Apnea period during sleep is proposed. Pneumatic method can measure heartbeat and respiration signal. Respiration signal can be considered as noise against heartbeat signal, and the decrease in the respiration signal due to Apnea increases the Average Mutual Information of heartbeat. The result of scaling analysis of the average mutual information is defined as threshold to detect the apnea period. The root mean square error between the lengths of Apnea measured by Strain Gauge using for reference and those measured by using the proposed method was 3.1 seconds. And, error of the number of apnea times judged by doctor and proposal method in OSAS patients was 3.3 times.View full abstractDownload PDF (718K)
Control
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Hisanosuke Kawada, Toru Namerikawa2009 Volume 45 Issue 1 Pages 18-26
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSThis paper addresses the bilateral control of nonlinear teleoperation with time varying delays. The proposed control strategies are two types of simple PD-type controllers which directly connect the master and slave robots by position and velocity signals over the delayed communication. For the velocity control, the first controller has a time varying D-gains which depend on the rate of change of delays and the second one has a constant D-gains which are designed under stability condition. Moreover the both controllers have explicit position feedback/feedforward control. Using Lyapunov-Krasovskii function, the delay-depend stability of the origin is shown for the range of the gains. Furthermore the proposed framework enforces master-slave position coordination and static force reflection. Several simulation and experimental results show the effectiveness of our proposed framework.View full abstractDownload PDF (683K) -
Takao Nambu2009 Volume 45 Issue 1 Pages 27-32
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSIn feedback stabilization for linear parabolic systems,a control scheme is designed so that the “state” of the system decays with a designated decay rate as t → ∞. An arbitrary linear functional of the state, which is subordinate to the state, also decays at least with the same decay rate. We study in the paper a class of linear parabolic systems of one dimension, and construct a specific control scheme such that a nontrivial linear functional decays exactly faster than the state.View full abstractDownload PDF (296K) -
Fumitoshi Sakai, Toshiharu Sugie2009 Volume 45 Issue 1 Pages 33-40
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSThis paper presents an identification method based on an iterative learning control (ILC) concepts for the multivariable continuous-time systems.For this purpose, a projection type ILC which updates the input in an appropriate parameter space is extended to the case of multivariable systems.The robustness against measurement noise is achieved through both projection of continuous-time I/O signals onto a finite dimensional space and noise tolerant learning algorithms. Finally, a numerical example demonstrate how the parameter estimation can be achieved through the proposed identification method in the presence of heavy measurement noises.View full abstractDownload PDF (649K)
Systems and Information
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Masato Nagayoshi, Hajime Murao, Hisashi Tamaki2009 Volume 45 Issue 1 Pages 41-50
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSThis paper presents a technique for reinforcement learning to deal with both discrete and continuous state space systems in POMDPs while keeping the state space of an agent compact. First, in our computational model for MDP environments, a concept of “ state space filtering ” has been introduced and constructed to make the state space of an agent smaller properly by referring to “ entropy ” calculated based on the state-action mapping. The model is extended to be applicable in POMDP environments by introducing the mechanism of utilizing effectively of history information. The extended model is capable of being dealt with a continuous state space as well as a discrete state space by the extended model. Here, the mechanism of adjusting the amount of history information is also introduced so that the state space of an agent should be compact. Moreover, some computational experiments with a robot navigation problem with a continuous state space have been carried out. The potential and the effectiveness of the extended approach have been confirmed through these experiments.View full abstractDownload PDF (588K) -
Takahiro Kagawa, Hideki Yamashina, Yoji Uno2009 Volume 45 Issue 1 Pages 51-59
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSAn efficient and stable gait control is an essential problem to develop a legged locomotor device for paraplegics. In this study, we investigate a necessary condition of the ballistic walking to avoid a backward balance loss. The condition derived by an inverted pendulum model is represented as a simple relationship between a position and velocity of a body center of mass at toe-off. The condition was validated through simulation experiments of a 7-link musculoskeletal model and gait measurement experiments of normal and paraplegic subjects. The results of the model simulation showed a good agreement with some predictions of the inverted pendulum model. The measured center of mass trajectories of normal and paraplegic gaits were satisfied with the necessary condition. These results suggest that the necessary condition is effective to avoid a backward falling during walking. In addition, energy input was required in a double support phase while the trajectory followed the ballistic movement of the inverted pendulum in a single support phase for a normal subject. These results suggest that a power assist control to be satisfied with the necessary condition during a double support phase and a ballistic gait generation during a single support phase are required for a paraplegic locomotor with efficiency and stability.View full abstractDownload PDF (938K) -
Tetsushi Ikeda, Hiroshi Ishiguro, Takuichi Nishimura2009 Volume 45 Issue 1 Pages 60-68
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSTo realize intelligent environments that understand and support our daily activities, it is important to observe positions and identities of people in the environment and many studies have been proposed using sensor networks. Floor sensors can reliably detect current positions of people and prevent invasion of privacy, but it is difficult to identify people. To solve the problem, we propose to integrate acceleration sensors that are attached to the human body. Since the signals from floor sensors and acceleration sensors are correlated when they observe the same person, these signals are not independent. The correlation between the signals is evaluated based on a statistical test to find correct association of positions to IDs. People tracking examples are shown to confirm the effectiveness of the proposed method. Significant improvement in correct association rate is achieved compared to the results using only floor sensors.View full abstractDownload PDF (701K)
Short Paper
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Sho Kosaka, Masayuki Hara, Jian Huang, Tetsuro Yabuta2009 Volume 45 Issue 1 Pages 69-71
Published: 2009
Released on J-STAGE: November 01, 2011
JOURNAL FREE ACCESSIt is generally thought that human beings have high-performance system in body movement.However,the mechanisms of body movement have not been clarified completely.In order to reveal mechanisms between human motion and vision cognition,this paper focuses on influence of visual illusion on the arm motion.View full abstractDownload PDF (1363K)
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