記述言語：英語   掲載種別：研究論文（学術雑誌）  

This paper presents a robust torsional vibration damper for variable-speed wind turbines based on the disturbance observer method. The damper is designed by explicitly taking into account the pole placement of the closed-loop system in the presence of model uncertainties. Unlike the conventional band-pass filter method, it is analyzed that the proposed method not only has good performance on noise attenuation but also can maintain the characteristics of the drivetrain system in the low-frequency region. The performance of other generator speed-based controllers, such as the blade pitch controller, can therefore be preserved without the retuning procedures. An experimental system having high consistency with a 2 MW wind turbine is developed and real-time hardware-in-the-loop experiments are carried out to demonstrate the effectiveness of the damper.

DOI： 10.1016/j.ifacsc.2020.100112

その他リンク： https://www.sciencedirect.com/science/article/pii/S2468601820300213?via%3Dihub

リポジトリ公開URL： https://hdl.handle.net/2324/7234386

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The integration of wave energy converters and a floating wind turbine has the potential to reduce the cost of energy, since they can share the mooring system and the infrastructure of the power grid. In this study, oscillating-water-column-type wave energy converters mounted on a semisubmersible-type floating wind turbine are presented. Water tank tests are carried out to illustrate that the wave energy converters can not only capture the wave energy but also help in reducing the motion of the floating platform when active control is applied. This study provides a new perspective on hybrid renewable energy application to widen renewable energy penetration by enhancing system reliability.

DOI： 10.1007/s00773-019-00671-y

リポジトリ公開URL： https://hdl.handle.net/2324/7234385

記述言語：英語   掲載種別：研究論文（学術雑誌）  

This paper addresses a fundamental study of a floating type shrouded wind turbine on the design, mathematical model and motion analysis. Several novel concepts are introduced to the system for cost reduction: a revolute hinge is applied between the tower and the nacelle to maintain the orientation of the nacelle even in a large tower inclination, a swashplate mechanism with cyclic control is employed for blade pitch regulation to improve the system controllability, a novel mooring system with a slewing bearing is utilized to build the passive yawing system, and an advanced spar-type floater is used to obtain high restoring performance with a short spar. Firstly, the design aspects of the main components of the system are given. Then, the numerical model including the structural model, hydrodynamic/aerodynamic model, and the control system is presented. The static and dynamic responses under both the operational situation and survival conditions are finally studied. The paper illustrates the probability of the shrouded wind turbine on floating offshore application, and can provide critical information for the optimization design in next stage. (C) 2018 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.renene.2018.09.028

リポジトリ公開URL： https://hdl.handle.net/2324/7234384

記述言語：英語   掲載種別：研究論文（学術雑誌）  

With the development of ocean energy exploration, reliable semisubmersible platforms with very small motion are expected to develop. Especially, in a floating offshore wind turbine (FOWT) system, the maximum pitching amplitude is required to be less than a few degrees. To reduce wave-induced pitch motion, a new type semisubmersible with suspensions and a design method of the suspension coefficients are presented. In practical case, an add-on wave energy dissipation device mounted on a floating platform, such as the combined wave-wind energy converter system, could be regarded as the suspension system. In this study, first, the conceptual semisubmersible is described. Then, the hydrodynamic loads to the semisubmersible are linearized so that the whole system is expressed by a state-space model. The suspension design problem is transformed into solving a constrained H-infinity optimization problem, which after all is the optimal controller design of a feedback system. Finally, numerical examples are performed to verify the effectiveness of the design. The results illustrate that the pitch motion of the semisubmersible can be remarkably reduced by the designed suspensions.

DOI： 10.1115/1.4033948

リポジトリ公開URL： https://hdl.handle.net/2324/4055229

記述言語：英語   掲載種別：研究論文（学術雑誌）  

With the development of ocean energy exploration, reliable floating platforms with very small motion are expected to develop. For instance, the maximum pitching amplitude of a floater for floating offshore wind turbine is required to be less than a few degrees. On the other hand, ocean waves contain abundance of untapped renewable energy with very high power density. Integration of floating platform with wave energy converters while reducing the structure interaction becomes significant for offshore development. In this paper, control of wave energy converters on reducing the pitch motion of a floating platform is studied. Firstly, a mathematical model of the whole system is proposed. The control of wave energy converters leads to solve a constrained optimization problem. Secondly, hybrid model predictive control is presented to synthesize the controller. Finally, numerical examples are given to verify the effectiveness of the proposed controller. It is shown that the reduction of pitch motion of the platform and the wave energy extraction are compatible.

DOI： 10.1016/j.ifacol.2016.10.434

リポジトリ公開URL： https://hdl.handle.net/2324/7234378

記述言語：英語   掲載種別：研究論文（学術雑誌）  

This paper presents a novel approach to reconstruct the output of linear systems in the case where the measured output is uniformly quantized. By fitting the quantized measurements with polynomials in a moving horizon manner, a smooth signal is reconstructed by solving a convex optimization problem with (1)-norm regularization. The quantization feature and the system models are taken into account in the optimization. A numerical example is given to show the excellent reconstruction performance of the proposed method. In addition, the proposed method is implemented in a high-precision linear stage through DSP, and its effectiveness is verified through experiments using a real positioning system.

DOI： 10.1002/asjc.950

リポジトリ公開URL： https://hdl.handle.net/2324/7234377

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ball-screw-driven stages are widely used in industry for long-range and high-precision fabrication. One of the main difficulties in dealing with high-precision motion control is the nonlinear friction, which originates at elastic deformation of the mechanical components. In this paper, first, a novel mechanical model of a ball-screw-driven stage is proposed to analyze the elastic deformation dynamics under various motion conditions. It is achieved that the mechanical deformation characteristic of fast motions differs from the case of slow motions in the zero-speed region, and therefore, performing friction compensation should take the motion conditions into account. Then, based on this observation, a sinc-function-based friction compensation method for slow motions including both reverse motions and nonreverse motions and a Sigmoid-function-based friction compensation method for fast reverse motions are proposed to improve the control performance. Thanks to the very few parameters, the proposed methods can save much trouble in design and maintenance and are particularly suitable for control purposes. Finally, the advantages of the proposed methods are evaluated by experiments.

DOI： 10.1109/TMECH.2014.2337933

リポジトリ公開URL： https://hdl.handle.net/2324/7234375

記述言語：英語   掲載種別：研究論文（学術雑誌）  

High-precision current control is demanded for many mechatronic systems to improve the static and dynamic performances. However, current measurement error inherent in the measurement system degrade the control accuracy, since the motor currents are not guaranteed to follow the desired references. In this paper, quantization error caused by analog-to-digital converters is studied. The dithering techniques combined with Kalman filter are proposed to suppress the quantization effects. First, two dithered systems, including the subtractively dithered and nonsubtractively dithered systems, are designed to whiten the quantization error. In the design of nonsubtractively dithered system, the probability characteristic of the metering noise is utilized to minimize the measurement noise level. Then, Kalman filter is designed to estimate the real current signals from the dithered current measurements. Since the variance of the total measurement error is theoretically calculable according to the proposed dithering techniques, Kalman gain can be determined analytically. Finally, simulations and experiments are performed to verify the effectiveness of the proposed approaches using a high-precision positioning system.

DOI： 10.1109/TII.2014.2307195

リポジトリ公開URL： https://hdl.handle.net/2324/7234374

記述言語：英語   掲載種別：研究論文（学術雑誌）  

This paper proposes a new approach to estimate the velocity of mechanical system in the case where the optical incremental encoder is used as the position sensor. First, the actual angular position is reconstructed via moving horizon polynomial fitting method by taking account of quantization feature and the plant dynamics. Then, the reconstruction signal is applied to a classical observer to obtain the velocity estimation. Its robustness against the position sensor resolution and the degree of the polynomial is discussed by some numerical examples. Experiments with very low-resolution encoder in low speed range also confirm its effectiveness.

DOI： 10.1115/1.4007065

記述言語：英語  

DOI： https://doi.org/10.3390/jmse12111995

出版者・発行元：Journal of Marine Science and Engineering  

In this paper, an experimental study is conducted to investigate the effectiveness of vibration dampers in suppressing vortex-induced vibration in a long, flexible catenary cable with a low mass ratio. The dampers, consisting of two small, symmetric, lightweight pipes clamped to the cable, are sparsely deployed along the cable to shape the vibration characteristics. The experimental results demonstrate that dampers significantly reduce the vibration amplitude by up to 60% and axial tension by up to 61% at high flow velocities, effectively suppressing the cable vibration in perpendicular flow. In addition, it is observed that the in-line and cross-flow vibration frequencies are approximately equal when the dampers are applied. This behavior contrasts with the conventional undamped catenary cable, where the in-line vibration frequencies are double those of the cross-flow frequencies.

DOI： 10.3390/jmse12111995

Scopus

出版者・発行元：Ocean Engineering  

In this paper, a numerical model based on Euler-Bernoulli beam theory and a single van der Pol wake oscillator model is proposed to study the vortex-induced vibration of a long flexible catenary cable with a low mass ratio. The wake model uses only one oscillator to describe the in-line and cross-flow vibration with consideration of their nonlinear coupling. An experiment on a flexible cable model in perpendicular flow is carried out to validate the proposed numerical model. Numerical results and experimental measurements are compared on the vortex-induced vibration responses including the maximum amplitude, axial tension, and vibration frequency. A sensitivity analysis of the parameters used in the numerical model has been carried out. Numerical simulations by the proposed numerical model with properly selected parameters have demonstrated that the vibration frequency and the axial tension can be well predicted, and the variation of the vibration amplitudes can also be properly captured. The lock-in phenomena and the axial tension variation of the long flexible catenary cable in perpendicular flow have been carefully studied both numerically and experimentally.

DOI： 10.1016/j.oceaneng.2024.117937

Web of Science

Scopus

記述言語：日本語   出版者・発行元：公益社団法人 日本船舶海洋工学会  

DOI： 10.14856/conf.37.0_793

CiNii Research

記述言語：英語  

Integrating wave energy converters into an offshore wind turbine can potentially reduce the levelized cost of energy. The influence of the wave energy converters on the foundation, however, can worsen the wind turbine motion so that both the efficiency and the fatigue life of the wind turbine would be degraded. In this study, wave energy converters are devised as the suspension system of the floater, and the chamber pressures are controlled to help reduce the floater motion in waves. A numerical model taking account of aero-hydro-servo-mooring coupled dynamics is proposed and a numerical study shows the effectiveness of the control method.

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

A promising concept of floating offshore overhead power transmission system (FOPTS), in which the power transmission tower is installed on a TLP-type floating foundation, is investigated experimentally and numerically to study its feasibility. A numerical method is proposed in which the potential flow theory is used to evaluate the floating foundation hydrodynamics. The lumped-parameter method with a wake oscillator model is applied to the aerodynamic modelling of the overhead in order to determine the wind-induced motion and the corresponding internal force of the conductors. Multi-body simulations are performed in Simscape® by coupling the floating foundation hydrodynamics and theconductor aerodynamics. Wind-tunnel experiments on a simplified FOPTS model are carried out to study the coupled motion of the TLP tower and the overhead conductor. The proposed numerical method is validated by comparison of the conductor tension and motion to the experiment. Numerical simulations have been performed under realistic offshore environments based on the meteorological data of the Sea of Japan. Wind-wave misalignment effects on the structure of the FOPTS are investigated, and the safety of the conductors, the mooring lines, and the sea navigation are discussed.

DOI： https://doi.org/10.1016/j.oceaneng.2023.115085

記述言語：英語   出版者・発行元：九州大学グリーンテクノロジー研究教育センター  

An improved numerical model is proposed to investigate the dynamics of an offshore overhead power transmission system. The hydrodynamic performance of the TLP type tower is evaluated by a potential flow theory method, and the aerodynamic performance of the electric wire is analyzed by lumped parameter method. The numerical model has been validated by comparison to water tank tests. The TLP type tower and the weight control system to reduce the body-wire interaction are newly designed for better performance in the condition of wind and wave. We found that the wire dynamics are significantly affected by the wave direction and wind direction through the numerical simulation, so the wind-wave misalignment conditions should be considered in the system safety assessment. Additionally, the safety situation of conductor wires under different environments can be studied by time-domain simulations, which can be used in system designs and feasibility discussions.

DOI： 10.5109/4842521

Scopus

CiNii Research

記述言語：英語   出版者・発行元：Elsevier  

Thrust force needs to be taken into account in the development of floating type shrouded wind turbines since it would lead to large tower inclination, and both the power conversion efficiency and the safety margin of the system would be reduced. In this study, a novel spar-type shrouded wind turbine using a hinge to mount the nacelle on the tower, which can maintain the nacelle in horizontal state even with large tower inclination, is studied based on a 1:100 model. The characteristics of the wind turbine are studied via wind tunnel experiments and wave basin experiments. In wind tunnel experiments, the wind speed-up performance of the shroud and the self-aligning property of the wind turbine are evaluated. In wave basin experiments, dynamical response of the wind turbine in idling, operational and parked modes are studied. A model-based attitude controller for stabilizing the nacelle is also proposed and the control performance is analyzed based on experimental results.

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Wind energy has shown promising advantages in reducing the greenhouse effect by minimizing carbon dioxide emissions to improve earth climate. Wind turbine which falls under the umbrella of renewable energy family promises cleaner environment while generating electricity from wind energy with no burnt fossil fuel. However, it portrays challenges in terms of high operating cost due to component failure. Thus this paper discusses on mitigating one of the problems related to wind turbine failure, the torsional vibration reduction in drive train. A generator torque control is investigated together with the particle swarm optimization technique in search for accurate parameters of the controller. This control strategy is a solution to low wind speed areas especially around South East Asian region. An augmented inverse model-based controller and band pass filter is proposed to obtain vibration attenuation at the dominant mode. The modelling endeavor is firstly obtained via particle swarm optimization search capability to obtain an accurate transfer function of the inverse model. A band pass filter (BPF) is then augmented with the inverse model as controller for torsional vibration suppression. Results have shown favorable comparison between the proposed and conventional methods in terms of vibration attenuation level.

DOI： 10.1016/j.procs.2017.01.211

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Optical encoders are extensively used for position measurements in motion control systems. The inherent quantization feature of encoders limits the control performance in many applications. This paper shows a way to reconstruct the smooth position signal from the quantized measurements. The method uses a polynomial fitting approach where the degree of polynomial is automatically selected via a convex optimization method. In addition, the information of the plant is exploited by combining an observer. The effectiveness of the proposed method is verified by simulations and experiments using a high-precision linear stage.

DOI： 10.3182/20130410-3-CN-2034.00058

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Accurate current signals are required for precise current control of AC motor drives. However, current measurement errors that involve metering error and quantization error are unavoidable because of the inaccuracy of current sensors and the quantizing feature of analog-to-digital converters in all digital motion control systems. The quantization error contains harmonic components that can induce torque ripple, thus deteriorating the control performance. Therefore, it is necessary to suppress the quantization effects. In this paper, two dithered systems, namely, the subtractively dithered system and nonsubtractively dithered system, are presented in order to remove the quantization-based harmonic components of the measured current signals by whitening the quantization error. Moreover, for ease of practical implementation, the design of dither signals is analyzed for nonsubtractively dithered system, considering cases where the metering error is uniform noise or Gaussian noise. It is shown that by applying the dither having a suitably chosen probability density function, the total measurement error can be rendered spectrally white. The effectiveness of the proposed methods is verified through simulations and experiments using a high-precision linear stage.

DOI： 10.1541/ieejjia.2.14

開催年月日： 2016年9月

記述言語：英語  

開催地：Trondheim   国名：日本国  

With the development of ocean energy exploration, reliable floating platforms with very small motion are expected to develop. For instance, the maximum pitching amplitude of a floater for floating offshore wind turbine is required to be less than a few degrees. On the other hand, ocean waves contain abundance of untapped renewable energy with very high power density. Integration of floating platform with wave energy converters while reducing the structure interaction becomes significant for offshore development. In this paper, control of wave energy converters on reducing the pitch motion of a floating platform is studied. Firstly, mathematical model of the whole system is proposed. The control of wave energy converters leads to solve a constrained optimization problem. Secondly, hybrid model predictive control is presented to synthesize the controller. Finally, numerical examples are given to verify the effectiveness of the proposed controller. It is shown that the reduction of pitch motion of the platform and the wave energy extraction are compatible.

開催年月日： 2016年6月

記述言語：その他   会議種別：口頭発表（一般）  

開催地：Busan   国名：大韓民国  

With the development of ocean energy exploration, reliable and low cost semi-submersible platforms are expected to develop. The maximum pitching amplitude of a floater for floating offshore wind turbine should be less than a few degrees to avoid fatigue failure. In this paper, a novel conceptual design of a new type semi-submersible with suspensions for suppressing the pitch motion is presented. Many wave energy dissipation devices, such as add-on wave energy converters to a floating platform, could be regarded as the suspension system in our design. Firstly, linear models are applied to approximate the radiation forces and wave exciting forces so that the whole motion system is represented by a state-space model. Then, we show that design of suspensions leads to synthesize a controller via solving a constrained H-infinity optimization problem. Finally, numerical examples are performed to verify the design and it can be shown that the pitch motion of the semi-submersible platform is remarkably reduced.

開催年月日： 2014年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Yokohama   国名：日本国  

Ball-screw-driven stages are extensively used in industry for long-range and high-precision fabrication thanks to their high efficiency and high ability to apply/withstand high thrust loads. However, spring-like nonlinear friction in zero-speed region significantly affects the control performance. In this paper, the mechanical deformation characteristics at zero-speed point after low deceleration and after high deceleration are analyzed. It is found that the mechanical deformation characteristic of fast motions differs from the case of slow motions in zero-speed region, and therefore performing friction compensation should take the motion conditions into account. Then, after introducing a variable to evaluate the elastic deformation of the total mechanical components, a novel friction compensation method for fast reverse motions using Sigmoid function is proposed to enhance the control performance by explicitly considering the elastic deformation. Finally, Experiments are performed to verify the effectiveness of the proposed method.

開催年月日： 2011年8月 - 2011年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Milan   国名：イタリア共和国  

This paper presents a new approach to reconstruct the plant output of linear time-invariant systems in the case where the available output measurement is quantized. By fitting the quantized measurement data with polynomials in a moving horizon manner, a smooth approximation of plant output is obtained via solving a convex optimization problem. Applying the signal to an observer, the plant output is reconstructed by taking account of the plant dynamics. It is guaranteed that the error between the true and the reconstructed output is bounded. Experimental validation is given by using a DC motor positioning system. It turns out that the proposed approach achieves small reconstruction error and accurate tracking control. In addition, the approach yields a smooth reconstruction signal so that the plant input is well behaved (or smooth) even if PID controller is employed for the plant subject to quantized output measurement.

開催年月日： 2024年1月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：Fukuoka   国名：日本国  

開催年月日： 2023年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：長崎県長崎市   国名：日本国  

リポジトリ公開URL： https://hdl.handle.net/2324/7234606

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：Saga   国名：日本国  

Integrating wave energy converters into an offshore wind turbine can potentially reduce the levelized cost of energy. The influence of the wave energy converters on the foundation, however, can worsen the wind turbine motion so that both the efficiency and the fatigue life of the wind turbine would be degraded. In this study, wave energy converters are devised as the suspension system of the floater, and the chamber pressures are controlled to help reduce the floater motion in waves. A numerical model taking account of aero-hydro-servo-mooring coupled dynamics is proposed and a numerical study shows the effectiveness of the control method.

リポジトリ公開URL： https://hdl.handle.net/2324/7234603

開催年月日： 2023年8月

記述言語：英語  

開催地：Shanghai   国名：中華人民共和国  

開催年月日： 2022年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Saga   国名：日本国  

Integrating wave energy converters into an offshore wind turbine can potentially reduce the levelized cost of energy. The influence of the wave energy converters on the foundation, however, can worsen the wind turbine motion so that both the efficiency and the fatigue life of the wind turbine would be degraded. In this study, wave energy converters are designed as a controlled suspension system, and an optimal semi-active control method having the predictive ability is proposed for reducing the motion of the foundation. In the controller design, the physical constraints and the passivity of the wave energy converters are also taken into consideration. A full numerical model taking account of aero hydro servo mooring coupled dynamics is proposed for a comprehensive analysis of the controller under various environmental conditions and different operational statuses.

開催年月日： 2021年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kyushu University   国名：日本国  

Numerical simulation has been carried out to investigate the interaction between electrical wire and floating tower for a new proposed offshore overhead power transmission system. The motion of the TLP-type floating tower is calculated by a potential flow theory method and dynamics of the wire is calculated by a lumped mass method. The numerical model is validated by comparing to available experimental data. In this study, a triangle TLP is newly designed for the floating tower and the interaction of the wire and the floating tower is investigated by a series of numerical simulation. It is found that the wire-floating tower interaction is significantly affected by the wave and wind direction, which should be carefully considered in the safety assessment of the system.

開催年月日： 2021年10月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2021年5月 - 2023年6月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン   国名：日本国  

開催年月日： 2020年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン   国名：日本国  

開催年月日： 2020年5月

記述言語：日本語  

開催地：オンライン   国名：日本国  

開催年月日： 2020年5月

記述言語：英語  

開催地：オンライン   国名：日本国  

開催年月日： 2018年9月 - 2023年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Taipei   国名：台湾  

開催年月日： 2018年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Taipei   国名：台湾  

Economic efficiency and structural reliability are strongly required for ocean energy exploration. The integration of wave energy converter and floating offshore wind turbine has the potential to reduce the cost of energy since they can share the mooring system and the infrastructure of power grid. In this study, oscillating-water-column-type wave energy converters mounted on a semisubmersible-type floating wind turbine are considered. The wave energy converter is designed not only to capture wave energy but also to work as a damper of the semisubmersible for helping on enhancing the fatigue life of the wind turbine. Controllers for the wave energy converter and wind turbine for reducing the pitch motion of the semisubmersible are also presented in the study. The experimental results illustrate that the pitch of semisubmersible can be reduced by the controllers in most of the cases. However, the effectiveness of the controllers could be limited by the capacity of the wave energy converter especially when the motion of the floating turbine is large.

開催年月日： 2018年6月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Yokohama   国名：日本国  

開催年月日： 2017年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：広島   国名：日本国  

開催年月日： 2016年5月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：大阪   国名：日本国  

開催年月日： 2016年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：名古屋   国名：日本国  

開催年月日： 2015年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：東京   国名：日本国  

開催年月日： 2015年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2014年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2014年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2013年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Vienna   国名：オーストリア共和国  

This paper presents a heuristic friction compensation approach for handling the springlike friction behaviors of a ball-screw-driven stage in zero-speed region. The friction compensation for the motion that the stage is decelerated to stop and then accelerated in the same direction, which is also referred to as non-velocity-reversal motion, is discussed in detail. As the elastic energy stored in mechanical components may not be completely released during non-velocity-reversal motion, the conventional compensation approaches may not work well. Therefore, some other sophisticated friction compensation approaches become necessary for this kind of motion. In this study, a velocity pattern recognition algorithm is presented as the first step to classify the velocity patterns in zero-speed crossing region. Then, sinc function is exploited to model the nonlinear springlike friction of the ball-screw-driven stage. It is proved that the friction can be properly compensated for both the reversal motion and non-reversal motion. Experiments are performed to verify the proposed approach and it is demonstrated that the control performance is significantly improved.

開催年月日： 2013年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2013年4月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hangzhou   国名：中華人民共和国  

開催年月日： 2013年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Yokohama   国名：日本国  

開催年月日： 2013年2月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2012年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Montreal   国名：カナダ  

Accurate current signals are required for precise current control of AC motor drives. However, current measurement error including the metering error and the quantization error is unavoidable due to the inaccuracy of current sensors and the quantizing feature of analog-to-digital converters. In this paper, the combination of dithering techniques and Kalman filter is presented to suppress the current quantization effects caused by AID converters. Firstly, the dithering system is designed to whiten the total current measurement error. Then, Kalman filter is exploited to estimate the real current signals from the whitened noise. The effectiveness of the proposed approach is verified via simulations and experiments using a high-precision stage.

開催年月日： 2012年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Nara   国名：日本国  

開催年月日： 2012年3月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2012年2月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Yokohama   国名：日本国  

開催年月日： 2011年3月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Okinawa   国名：日本国  

開催年月日： 2010年9月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Oska   国名：日本国