Reduction of Hull Whipping in Slamming by Active Control System

1994 ◽  
Vol 38 (02) ◽  
pp. 115-122
Author(s):  
Wen-Jeng Hsueh ◽  
Ya-Jung Lee
Keyword(s):  
Control System ◽  
Active Control ◽  
High Speed ◽  
Active Vibration Control ◽  
Mathematical Formulation ◽  
Active System ◽  
Hull Girder ◽  
Hydraulic Servo ◽  
Active Vibration ◽  
Active Control System

The reduction of hull girder whipping in slamming by an active control system is investigated. Under the consideration of hull flexibility, a mathematical formulation is developed for the whipping of a hull, subject to slamming, and including an active vibration control system consisting of a tuned mass and hydraulic servo system. Using the optimal theory, the control law of the active system is determined. In addition, a closed-loop estimator is introduced to estimate the distribution of hull motion, which is required to compute the actuator output of the active system. Finally, a numerical example of an application to a 205-ton high-speed craft is described. The results show that the whipping will be reduced significantly. The whipping acceleration and induced stress in particular are reduced more than 95% within 2 sec by this scheme.

Bridge Life Extension Using Semi-Active Vibration Control

2013 ◽  
Author(s):  
G. Nelson ◽  
R. Rajamani ◽  
A. Gastineau ◽  
A. Schultz ◽  
S. Wojtkiewicz
Keyword(s):  
Control System ◽  
Resonant Frequency ◽  
Vibration Control ◽  
Active Control ◽  
Active Vibration Control ◽  
Life Extension ◽  
Peak Strain ◽  
Steel Bridge ◽  
Active Vibration ◽  
Active Control System

The fatigue life of a bridge can be extended by fifty years just by reducing the peak strain levels it experiences by 33%. This paper utilizes a dynamic model of the Cedar Avenue tied arch steel bridge in Minnesota to investigate active control technologies for peak strain reduction. Simulations show that the use of passive structural modification devices such as stiffeners and dampers is inadequate to reduce the key resonant peaks in the frequency response of the bridge. Both active and semi-active vibration control strategies are then pursued. Active vibration control can effectively reduce all resonant peaks of interest, but is practically difficult to implement on a bridge due to power, size, and cost considerations. Semi-active control with a variable orifice damper in which the damping coefficient is changed in real-time using bridge vibration feedback can be practically implemented. Simulation results show that the proposed semi-active control system can reduce many of the resonant peaks of interest, but is unable to reduce the response at one key resonant frequency. Further analysis reveals that the location of the actuator on the bridge chosen for the semi-active controller is inappropriate for controlling the specific resonant frequency of issue. By modifying the actuator location, it would be possible to obtain control of all bridge resonant frequencies with the semi-active control system.

Hardware Design for Active Vibration Isolation Controller

2011 ◽  
Vol 211-212 ◽  
pp. 1061-1065
Author(s):  
Qiang Hong Zeng ◽  
Shi Jian Zhu ◽  
Jing Jun Lou ◽  
Shui Qing Xie
Keyword(s):  
Control System ◽  
Vibration Control ◽  
Active Control ◽  
High Speed ◽  
Vibration Isolation ◽  
Active Vibration Control ◽  
Signal Acquisition ◽  
Acceleration Sensor ◽  
Series Acceleration ◽  
Active Vibration

The active vibration control system are described in this paper, and the controller was designed for the active control system, the controller is based on ARM Cortex M3 microcontroller core, ICP series acceleration sensor is use for signal acquisition module, the A / D converter module was designed based on ADS1158 chip, the D/ A converter module was designed based on DAC8564 chip. The controller has the characteristics of high speed and versatility.

Application of a Bandpass Filter for the Active Vibration Control of High-Speed Rotors

2019 ◽  
Vol 24 (3) ◽  
pp. 608-615 ◽  
Author(s):  
Miroslav Pawlenka ◽  
Miroslav Mahdal ◽  
Jiri Tuma ◽  
Adam Burecek
Keyword(s):  
Control System ◽  
Vibration Control ◽  
High Speed ◽  
Control Algorithm ◽  
Bandpass Filter ◽  
Active Vibration Control ◽  
Orthogonal Direction ◽  
Sliding Bearings ◽  
Active Vibration ◽  
Proportional Controller

This study concerns the active vibration control of journal bearings, which are also known as sliding bearings. The control system contains a non-rotating loose bushing, the position of which is controlled by piezoelectric actuators. For governing the respective orthogonal direction of the journal motion, the control algorithm realizes a proportional controller in parallel with a bandpass filter of the IIR type. The bandpass filter is of the second order and its centre frequency is self-tuned to be the same as the whirl frequency that results from the instability of the bearing journal due to the oil film. The objective of active vibration control is to achieve the highest operational speed of the journal bearing at which the motion of the rotor is stable. The control algorithm for the active vibration control is implemented in Simulink and realized in a dSPACE control system.

The Design and Application of Piezoelectric Friction Damper with Self-Powered and Sensing Control System

2010 ◽  
Vol 163-167 ◽  
pp. 2477-2481
Author(s):  
Na Xin Dai ◽  
Ping Tan ◽  
Fu Lin Zhou
Keyword(s):  
Control System ◽  
Vibration Control ◽  
Active Control ◽  
Mechanical Energy ◽  
Active Vibration Control ◽  
Friction Damper ◽  
Active Vibration ◽  
Self Powered ◽  
Control Equation ◽  
Converse Piezoelectric Effect

To make the active and semi-active vibration control system in civil engineering get rid of external power supply, a new piezoelectric friction damper with self-power and sensing is designed in this paper and a semi-active control system based on this damper is presented. This system includes three key parts: a piezoelectric friction damper, a power generator based on the piezoelectric stack electro-mechanical energy conversion and a control circuit. It makes full use of the direct and converse piezoelectric effect. At the same time, it also overcomes the deficiency that the frictional force as damping can not be accurately desired in semi-active vibration control system. On the basis of it, the control equation of PFD is formulated. Numerical simulations for seismic protection of story isolation equipped with this system excited by a historical earthquake are conducted by MATLAB. Skyhook control is used to command a piezoelectric friction damper in the semi-active control. It is noticed that only one accelerometer is needed to monitor the response to realize the skyhook control, which greatly simplifies the classical semi-active vibration control system.

The Dynamic Analysis of an Energy Storage Flywheel System With Hybrid Bearing Support

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Hongchang Wang ◽  
Shuyun Jiang ◽  
Zupei Shen
Keyword(s):  
Control System ◽  
Energy Storage ◽  
Active Control ◽  
High Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Squeeze Film ◽  
Transmitted Force ◽  
Hybrid Bearing ◽  
Active Control System

Active magnetic bearings and superconducting magnetic bearings were used on a high-speed flywheel energy storage system; however, their wide industrial acceptance is still a challenging task because of the complexity in designing the elaborate active control system and the difficulty in satisfying the cryogenic condition. A hybrid bearing consisting of a permanent magnetic bearing and a pivot jewel bearing is used as the support for the rotor of the energy storage flywheel system. It is simple and has a long working life without requiring maintenance or an active control system. The two squeeze film dampers are employed in the flywheel system to suppress the lateral vibration, to enhance the rotor leaning stability, and to reduce the transmitted forces. The dynamic equation of the flywheel with four degrees of complex freedom is built by means of the Lagrange equation. In order to improve accuracy, the finite element method is utilized to solve the Reynolds equation for the dynamic characteristics of the squeeze film damper. When the calculated unbalance responses are compared with the test responses, they indicate that the dynamics model is correct. Finally, the effect of the squeeze film gap on the transmitted force is analyzed, and the appropriate gap should be selected to cut the energy loss and to control vibration of the flywheel system.

scholarly journals Development and Implementation of a Multi-Channel Active Control System for the Reduction of Road Induced Vehicle Interior Noise

Actuators ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 52 ◽  
Author(s):  
Gunnar Gäbel ◽  
Jonathan Millitzer ◽  
Heiko Atzrodt ◽  
Sven Herold ◽  
Andreas Mohr
Keyword(s):  
Control System ◽  
Active Control ◽  
Noise Level ◽  
Interior Noise ◽  
System Level ◽  
Active System ◽  
Vehicle Interior ◽  
Full Vehicle ◽  
System Level Simulation ◽  
Active Control System

An optimized driving comfort with a low interior noise level is an important intention in the passenger car development process. The interior noise level caused by the dynamic interaction between the rolling tyre and the rough road surface and transmitted via the car-body is a significant component of the entire noise level. To reduce the road induced interior noise, in general, the chassis system has to be optimized. Passive measures often induces a trade-off between vehicle dynamics and driving comfort. To overcome this disadvantage in this paper, the development and realization of an active measure is proposed. For the purpose of active mechanical decoupling, an active control system is developed, the feasibility of the integration is investigated and its noise reduction potential is identified by vehicle tests. In a first step, a classical multi-channel and experimental-based structure-borne transfer path analysis of the full vehicle is realized to determine the dominant transfer paths. The concept for the active mount system (active mounts, multi-channel control system, sensors) is developed and parametrized by system level simulation. Mechanical components and power electronics of the active system are designed, manufactured and tested in the laboratory. Subsequently, the entire active system is integrated into the vehicle. The broadband adaptive feedforward algorithm is extended by certain measures in order to improve robustness and performance. Full vehicle tests are used to quantify the required specifications and the achieved effectiveness of the active vibration control system.

Active Control for Whirling Motion of Flexible Rotor

1991 ◽  
Vol 3 (4) ◽  
pp. 360-364 ◽  
Author(s):  
Takakazu Ishimatsu ◽  
◽  
Takashi Shimomachi ◽  
Nobuyoshi Taguchi ◽  
Keyword(s):  
Control System ◽  
Vibration Control ◽  
Active Control ◽  
Active Vibration Control ◽  
Digital Controller ◽  
Flexible Rotor ◽  
Whirling Motion ◽  
Active Vibration ◽  
Electromagnetic Damper

In a rotational machine, unbalance on the rotor is formidable since it causes resonance synchronized with the rotation of the rotor. In order to suppress this unfavorable vibration, we built an active vibration control system of flexible rotor using an electromagnetic damper. Our control system is composed of a digital controller to suppress the rotationally synchronized whirling motion and also a conventional analogue controller. Using our control system, whirling motion of the rotor under various rotating speeds was suppressed significantly.

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