Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
ZHU HONGZHONG Last modified date:2024.06.03

Associate Professor / Renewable Energy Center / Research Institute for Applied Mechanics

1. Hongzhong Zhu, A Study on Floating Type Hybrid Wind-Wave Energy Harvesting System: Towards Floater Motion Reduction, The 1st International Symposium on Renewable Energy and Hydrodynamics, 2023.08.
2. Hongzhong Zhu,Changhong Hu,Shigeo Yoshida, A Study on Integration of Floating Offshore Wind Turbine and Point-Absorber Wave Energy Converters, 第29回海洋工学シンポジウム, 2022.03, 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..
3. Ruo Luo, Hongzhong Zhu, Changhong Hu, A Study on Electrical Wire and Floating Tower Interaction for an Offshore Overhead Power Transmission System, International Exchange and Innovation Conference on Engineering & Sciences (IEICES), 2021.10, 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..
4. Hongzhong Zhu,Ruo Luo,Changhong Hu,Joichiro Noda, An Experimental Study on Tower-Wire Interaction for Offshore Overhead Power Transmission Concept, 日本船舶海洋工学会講演会, 2020.11.
5. Hongzhong Zhu, Changhong Hu, Makoto Sueyoshi, Masanori Kobayashi, Numerical Study on a Multi-Body Ship Towing System for a Floating Offshore Tower, 日本船舶海洋工学会講演会, 2020.05.
6. Hongzhong Zhu,Makoto Sueyoshi,Changhong Hu,Shigeo Yoshida, A Study on Integration of Wave Energy Converter and Semi-submersible Floating Wind Turbine: A Water Tank Test, The 4th Asian Wave and Tidal Energy Conference, 2018.09, 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..
7. Yingyi Liu,Shigeo Yoshida,Hiroshi Yamamoto,Akinori Toyofuku,Changhong Hu,Makoto Sueyoshi,Hongzhong Zhu, Release of a reliable open-source package for performance evaluation of ocean renewable energy devices, The 4th Asian Wave and Tidal Energy Conference, 2018.09.
8. Shigeo Yoshida, Endo Yudai,Hongzhong Zhu,Takada Ao,Hara Yutaka, Aeroelastic Simulation Tool for Large Scale Vertical Axis Wind Turbine, Grand Renewable Energy 2018, 2018.06.
9. Hongzhong Zhu, Makoto Sueyoshi, Changhong Hu, Shigeo Yoshida, Modelling and Attitude Control of a Shrouded Floating Offshore Wind Turbine with Hinged Structure in Extreme Conditions, 2017 IEEE 6TH INTERNATIONAL CONFERENCE ON RENEWABLE ENERGY RESEARCH AND APPLICATIONS, 2017.12, This paper addresses the modeling and attitude control of a novel shrouded floating wind turbine with hinged structure in harsh environmental conditions. Firstly, Sim Mechanrcs (TM) is applied to model the mechanical components of the wind turbine system. Secondly, the wave- and wind- loads acting on the system are respectively calculated based on Morison's equation and blade element momentum theory. Controllers of the elevator and the rudder located at the upwind side are designed based on linearized models to enhance the stability of the system. Numerical examples with three extreme weather conditions are finally performed to verify the effectiveness of the controllers. The results demonstrate that the pitching motion of the nacelle can be regulated to be within 3 degrees in the examples. In addition, the wind turbine could yaw itself stably toward the wind direction..
10. Hongzhong Zhu, Shigeo Yoshida, Hiroyuki Kajiwara, Yasuyuki Ogawa, Shigeyuki Nakada, Junji Ono, A Study on Torsional Vibration Reduction for Variable-Speed Variable-Pitch Wind Turbines, 2017 IEEE INTERNATIONAL CONFERENCE ON MECHATRONICS (ICM), 2017.02, As the size of the wind turbines increases, the structural loads causing fatigue stress on mechanical components become more dominant. Torsional vibration reduction in drivetrain helps to reduce the stress and avoid potential resonances with power grid system. In this study, a new approach based on disturbance observer and band-pass filter is proposed. The design of the parameters leads to solve a constrained optimization problem. The stability of the system can be guaranteed by the constraint conditions. The effectiveness of the proposed method is confirmed via simulations and experiment..
11. Hongzhong Zhu, Changhong Hu, A Study on Control of Wave Energy Converter for Motion Suppression of Semisubmersible, 10th IFAC Conference on Control Applications in Marine Systems, 2016.09, 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..
12. Hongzhong Zhu,Changhong Hu, Control of a Combined Floating Platform with Wave Energy Converter, 日本船舶海洋工学会講演会, 2016.05.
13. Hongzhong Zhu, Changhong Hu, Yingyi Liu, Optimal Suspension Design of a Semi-Submersible Platform, The 3rd Multi-symposium on Control Systems, 2016.03.
14. Hongzhong Zhu,Hiroshi Fujimoto, High-Precision Control of Ball-Screw-Driven Stages Considering Load-Side Rolling Friction, メカトロニクス制御研究会・モーションコントロール, 2014.09.
15. Hongzhong Zhu, Hiroshi Fujimoto, Proposal of Fast and High-Precision Control for Ball-Screw-Driven Stage by Explicitly Considering Elastic Deformation, IEEE 13TH INTERNATIONAL WORKSHOP ON ADVANCED MOTION CONTROL, 2014.03, 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..
16. Hongzhong Zhu,Hiroshi Fujimoto, An Algorithm of Smooth Output Reconstruction for Linear Systems with Quantized Measurements, SICE 1st Annual Symposium on Control Systems (MSCS-2014), 2014.03.
17. Hongzhong Zhu, Hiroshi Fujimoto, Proposal of Nonlinear Friction Compensation Approach for a Ball-Screw-Driven Stage in Zero-Speed Region including Non-Velocity-Reversal Motion, 39TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY (IECON 2013), 2013.11, 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..
18. Hongzhong Zhu,Hiroshi Fujimoto, High-Precision Control for Ball-Screw-Driven Stage in Zero-Speed Region by Explicitly Considering Elastic Deformation, IEEJ Technical Meeting Record, 2013.09.
19. Hongzhong Zhu,Hiroshi Fujimoto,Toshiharu Sugie, Proposal of Position Reconstruction with Polynomial Fitting Approach for Precise Motion Control, IFAC-Mechatronics, 2013.04.
20. Hongzhong Zhu,Hiroshi Fujimoto, Sinc-Function-Based Friction Compensation for Ball-Screw-Driven Stage in Zero-Velocity Region including Non-Velocity-Reversal Motion, 産業計測制御研究会, 2013.03.
21. Hongzhong Zhu, Hiroshi Fujimoto, Overcoming Current Quantization Effects for Precise Current Control by Combining Dithering Techniques and Kalman Filter, 38TH ANNUAL CONFERENCE ON IEEE INDUSTRIAL ELECTRONICS SOCIETY (IECON 2012), 2012.10, 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..
22. Hongzhong Zhu,Hiroshi Fujimoto, Overcoming Current Quantization Effects for Precise Current Control by Extended Dithering Techniques, SICE 12th Annual Conference on Control Systems, 2012.03.
23. Hongzhong Zhu, Hiroshi Fujimoto, Toshiharu Sugie, Servo Performance Enhancement of Motion System using Quantized Output Reconstruction Approach, 産業計測制御研究会, 2012.02.
24. Hongzhong Zhu, Toshiharu Sugie, Reconstruction of Plant Output from Quantized Measurement—A Moving Horizon Polynomial Fitting Approach, 18th IFAC World Congress, 2011.08, 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..
25. Hongzhong Zhu,Toshiharu Sugie, A New Algorithm of Output Reconstruction for Linear Systems with Quantized Measurement, SICE 11th Annual Conference on Control Systems, 2011.03.
26. Hongzhong Zhu,Toshiharu Sugie, Reconstruction of Plant Output Based on Quantized Measurements for LTI Systems ---A Polynomial Fitting Approach, 39th Control Theory Symposium, 2010.09.