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Volume 51, Issue 12
Displaying 1-8 of 8 articles from this issue
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Paper
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Yoshiro FUKUI, Hisakazu NAKAMURA2015 Volume 51 Issue 12 Pages 803-813
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSWe proposed a Sontag-type feedback controller by using a locally semiconcave practical control Lyapunov function (LS-PCLF) for asymptotic stabilization of a nonlinear system defined on a non-contractible manifold. We also proposed a design method of a nonsmooth control Lyapunov function called the multilayer minimum projection method. However, whether the method can be used as an LS-PCLF design method is not discussed, and we cannot design a controller by using the method and the controller in this situation. In this paper, we study a disassembled differential of a locally semiconcave function to handle an LS-PCLF. The minimal and maximal disassemble differentials, which are special types of a disassembled differential, are introduced. We elucidate that a set of reachable gradients and the Fréchet differential are equivalent to the minimal and maximal disassembled differential, respectively. Based on this fact, we prove that this method can be used as an LS-PCLF design method.View full abstractDownload PDF (897K) -
Kazuhiko MURASAKI, Kyoko SUDO, Yukinobu TANIGUCHI2015 Volume 51 Issue 12 Pages 814-821
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSAt present, manhole covers seem to cover a large percentage of the road surface. If a manhole cover becomes worn, it must be replaced because a worn cover can cause skidding and accidents. Staff have to check the condition of all covers periodically, and replace them if they are damaged. Because it takes too much time and manpower to check them manually, a system that can check them automatically by some remote sensor is urgently required. However, the detection of manhole cover wear has not been well studied. Our solution is to use image processing. We propose example-based approach using LBP feature, which is useful for texture recognition, considering the wear estimation problem as texture recognition. Feature selection utilizing measured data of wear to use only helpful features for wear estimation and patch extraction from images to estimate wear locally realize accurate estimation in spite of large variety of environments. Experiments with actual photos of manhole covers show that our approach achieved wearing detection accuracy scores of 0.95 in ROC/AUC scores, which is sufficient to help actual maintenance.View full abstractDownload PDF (3709K) -
Takashi IRITA, Toru NAMERIKAWA2015 Volume 51 Issue 12 Pages 822-828
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSEnsuring cyber security of smart grid based on supervisory control and data acquisition using information and communications technology has been becoming a major challenge. Especially, a replay attack is a dangerous cyber attack affecting integrity and authorization. The goal of this paper is to detect replay attack that is one of cyber attacks on the sensors of a control system. We propose a detecting method adding intentional noise to sensors as code signal playing a time-stamping part. Replay attack can immediately be reflected by using fault diagnosis matrices that are composed of the estimator and observed values. Finally, we show simulation results to analyze effectiveness of the proposed method.View full abstractDownload PDF (877K) -
Yusuke FUJIMOTO, Ichiro MARUTA, Toshiharu SUGIE2015 Volume 51 Issue 12 Pages 829-835
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSThis paper proposes a new data-driven control method with non-parametric map. The method yields the input for tracking control by minimizing a stochastic cost function which consists of I/O data set of the plant. One of the advantages of the proposed method is that it does not need a prior information about the nonlinear system such as their structure. An experiment is given to show the effectiveness of the proposed controllers.View full abstractDownload PDF (1085K) -
Toru KANO, Michihiko KOSEKI2015 Volume 51 Issue 12 Pages 836-844
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSX-ray CT (Computed Tomography) is a technique that can generate cross-sectional images of an object. This technology has spread rapidly in the field of diagnosis and inspection, and have provided significant benefits for our lives. However, when metal objects are present in the X-ray projection, a strong radial noise called metal artifacts arises and makes it difficult to diagnose and inspect. Even though various studies to reduce metal artifacts have been conducted, the problem is not resolved yet. In order to reduce these artifacts, we have proposed new algorithms based on the FBP(Filtered back projection), which remains the most widely used reconstruction method in CT. On the other hand, iterative reconstruction (IR) has emerged as a new CT reconstruction technique in recent years. IR requires a lot of computation time, however, it enables reduction in pixel noise or artifacts. In this paper, we proposed a new reconstruction algorithm to reduce metal artifacts based on IR. The algorithm utilizes the energy information to apply the exact successive approximation. Validation was performed using a simple experimental phantom. Our results demonstrate that the new algorithm effectively reduces metal artifacts in certain situations.View full abstractDownload PDF (3526K) -
Hironori OSHIMA, Tatsuo NARIKIYO, Michihiro KAWANISHI, Mitsuhisa SUZUK ...2015 Volume 51 Issue 12 Pages 845-857
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSPower assist robotic systems and wearable exoskeletons have been studied in various fields such as welfare and medical service. In most of the available studies, researchers have been developed the wearable power assist robots of biped walking type. Some of these are utilized in the welfare and medical services. However, such systems have poor stability during walking. Therefore, paraplegic persons cannot use these systems without extra supportive devices. In this study, we consider the four-legged walking that is characterized by knuckle walking of anthropoidea. This walking can perform stable walking and running with maintaining the upstanding posture. To implement the upstanding walking in walking support system for paraplegic persons, we develop an upstanding four-legged wearable power assist robot specialized for walking support. Finally effectiveness for walking support has been demonstrated by experiments involved with healthy subjects.View full abstractDownload PDF (6278K) -
Daisuke NAKANISHI, Yuichiro SUEOKA, Yasuhiro SUGIMOTO, Koichi OSUKA2015 Volume 51 Issue 12 Pages 858-865
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSIt has been widely known that robots driven by a McKibben pneumatic actuator (MPA) generates stable motions in spite of an unsophisticated control and a simple actuator model. After deriving a MPA model from the pressure and the elasticity, we examine the validity of it via numerical analyses and physical experiments. Then, we derive stability condition for the standing posture of the 2-dimensional-leg robot equipped with extensor and flexor MPAs. Moreover, we show the correlation of the standing posture and the joint stiffness with respect to the combinations of two MPA pressures, respectively. Finally, we also verify that the standing posture and the joint stiffness can be individually controlled by regulating the values of two MPA pressures.View full abstractDownload PDF (1463K) -
Masakazu MUKAI, Hiroshi AOKI, Taketoshi KAWABE2015 Volume 51 Issue 12 Pages 866-872
Published: 2015
Released on J-STAGE: December 18, 2015
JOURNAL FREE ACCESSThis paper considers model predictive control for ecological driving based on the traffic signal information. In the control problem it is assumed that the traffic signal information can be obtained for the prediction horizon. The control problem is formulated as a mixed integer programming problem. The computer simulation is carried out to show the effectiveness of the proposed control algorithm. In the simulation the energy consumption is reduced more than 15% in comparison with the driver mimic control which does not use traffic signal information.View full abstractDownload PDF (2375K)
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