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Volume 53, Issue 12
Displaying 1-5 of 5 articles from this issue
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Paper
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Yoshiro WASHIKITA, Toshiyuki OHTSUKA2017 Volume 53 Issue 12 Pages 625-632
Published: 2017
Released on J-STAGE: December 16, 2017
JOURNAL FREE ACCESSThis paper describes discrete-time models for a system that consists of subsystems connected by time-delay elements representing the moving time of a material from one subsystem to another. When the moving speed is variable and given as prior information, it leads to an imprecise model to simply replace the time-invariant parameters with the time-variant ones. Therefore, we propose a model consisting of a sufficient number of time-invariant delay operators and an output expressed by a linear combination of the outputs of the delay operators. In this model, the update formula for the state variable is time-invariant and the time-varying coefficients of the output equation are determined by the position of the material in the time-delay element. Observer-based state estimation for the proposed model is also discussed. It is shown that the response of the observer with uniform gains results in a time-invariant first-order lag even when the moving speed changes.
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Yuta YONEZAWA, Kazuma SEKIGUCHI, Kenichiro NONAKA2017 Volume 53 Issue 12 Pages 633-643
Published: 2017
Released on J-STAGE: December 16, 2017
JOURNAL FREE ACCESSThis paper proposes a velocity observer for caster wheel odometers resisting steady-state error. The proposed method is established by attaching a feedback loop of error integration to extended Luenberger observer (ELO). The stability of the proposed observer is proved, moreover, the steady-state error converges to a bounded area where the bounds are defined by design parameters. This fact guarantees that the proposed method is robust against a certain class of model error as well as measurement noise. The advantage over the simple ELO or the conventional approximated differentiator is verified in numerical simulations and experiments.
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Shun TSUNASAWA, Shinji OHYAMA2017 Volume 53 Issue 12 Pages 644-653
Published: 2017
Released on J-STAGE: December 16, 2017
JOURNAL FREE ACCESSIn this paper, multi-speaker localization methods using voice signal are proposed. Sound source localization systems consisting of many microphones have been widely researched. In our laboratory, we have researched sound source localization of persons based on TDOA (Time Difference of Arrival) between distributed microphones for the purpose of efficient use of air conditioner and lighting in the office . Localization systems based on sound such as footsteps or voice are superior to those based on image data in terms of privacy-consciousness and utility in the dark. As sound source localization methods, beamforming, subspace methods and TDOA-based methods are widely used. CSP (Cross-power Spectrum Phase) analysis is one of the most famous method to estimate TDOA. We have researched sound source localization methods using CSP analysis because it spends less calculation cost than beamforming or subspace methods. However, CSP analysis doesn't work well by itself in the real office environment because of sound lasting for a long time, reverberations, low SNR, and so on. The main cause of difficulty in sound source localization in such a case is the “weak correlation” between different sound signals. In this paper, it is shown that the bad effect of the “weak correlation” can be improved by our proposed methods, Wiener-filter-based CSP analysis and H-CSP (Histogram-CSP) analysis. H-CSP analysis is a statistics data analysis method for CSP coefficients which uses the histogram of CSP coefficients. In this research, the effectiveness of proposed methods are shown by sound source localization experiments in the case sound sources are stable and the case sound sources are moving.View full abstractDownload PDF (2047K) -
Satoshi KUMAGAI, Ryosuke MORITA, Satoshi ITO2017 Volume 53 Issue 12 Pages 654-662
Published: 2017
Released on J-STAGE: December 16, 2017
JOURNAL FREE ACCESSOur previous works revealed that the equilibrium perception detected by the subjective upright posture is affected from the motor-learning of the balancing task even in the seated posture. However, the same motor learning sometimes evoked the different perceptual change, the shift of the subjective upright posture in the opposite direction. Investigating this reason, this paper analyzes the motor-learning that contains two kinds of disturbance: inertial disturbance caused by the lateral slides of the whole stool, and rotating disturbance featured by the shift of the virtual rotation axis of the stool roll direction. As the results, three factors, the relative phase of CoP with respect to the motion of the virtual rotation axis and the sign and the magnitude of the mean horizontal deviation of the trunk, specify two kinds of posture during the motor learning. At one posture, the trunk inclines at the basis near the pelvis to the same direction of the disturbance and shows a large horizontal deviation measured at the neck. On the other hand, at the other posture, the trunk bends first to the same direction of the disturbance at the base and bends again to the opposite direction near the waist, indicating a small horizontal deviation. The posture of the balancing task during the motor learning seems to determine the direction of the perceptual change for the participants that have reduced the relative phase, i.e., the delay, of CoP movement from the disturbance implying the progression of the motor learning.View full abstractDownload PDF (1619K) -
Junya YAMAUCHI, Made Widhi Surya ATMAN, Takeshi HATANAKA, Masayuki FUJ ...2017 Volume 53 Issue 12 Pages 663-670
Published: 2017
Released on J-STAGE: December 16, 2017
JOURNAL FREE ACCESSIn this paper, we propose a robotic network cooperative control law under inter-robot communication delay. This controller guarantees human operator enabled positions/velocities synchronization of robotic network to human desired values. First, we show passivity of the interconnected system of each robot and proposed control law. Furthermore, passivity of robotic network is also shown by applying scattering transformation to communication channels between each robot. Then, positions/velocities synchronization to human desired values are proved with input strict passivity assumptions of human's decision making process. Finally, we demonstrate the effectiveness of the presented control law through simulation and experiment.View full abstractDownload PDF (2545K)
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