Development of a Vibration Control System for the Coil Drum of MRI equipment

MRI设备线圈滚筒振动控制系统的研制

基本信息

批准号：
04555052
负责人：
TANI Junji
金额：
$ 9.41万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04555052/
关键词：
Vibration Control Electromagnetic Force MRI equipment Coil Drum

项目摘要

High level noise induced in MRI equipments has been a main obstacle for their wide application in medical diagnosis. The noise is caused by the vibration of the cylindrical shell used to support the gradient magnetic field coils in MRI.A model of the coil drum with reduced size is made from polymer films and piezoelectric films. In the control of the shell vibration, two parts of the piezoelectric films is used as bending actuators so that no external actuators are needed. The disturbance cancellation method is used since the shell is excited by pre-determined forces. The relation between the size, position and output magnitude of the actuators and control effect is also discussed. Experiment and simulation were carried out when the shell was excited at resonance frequencies of three main modes. The results shows that the minimum amplitude of controlled vibration varies for different modes.Next, a method was proposed to control the vibration of a cylindrical shell system. The cylindric … More al shell system consists of a polymeric film in the middle and one piezoelectric film on each side. The piezoelectric films are divided into several parts, some of which function as distributed actuators.Analysis of the shell vibration under periodic excitation is performed by means of the modal expansion method. A controller is designed based on H_* control theory and the results of modal analysis. Numerical simulation and experiment were carried out using the designed controller and the results show good agreement, as well as the effectiveness of this method in suppression of forced vibration.At last, a study on vibration control of a cylindrical shell using distributed piezoelectric sensors and actuators which are parts of the shell wall. Modal expansion method is used in estabishment of the state equation of the system. The robust control including H_* control theory and mu synthesis method are applied to the design of the controller which satisfies given control performance and robust stability. Simulation and experiment are carried out when the shell is excited at the resonance frequency of a controlled mode. The results shows good agreement between simulation and experiment, as well as the effectiveness of the method using distributed sensors and actuators, and H_* control theory and mu-synthesis method. Less

在MRI设备中引起的高水平噪声一直是其在医学诊断中广泛应用的主要障碍。噪声是由用于支撑MRI中梯度磁场线圈的圆柱形壳的振动引起的。尺寸降低的线圈模型由聚合物膜和压电膜制成。在控制壳振动的过程中，压电膜的两个部分用作弯曲执行器，因此不需要外部执行器。由于壳被预定的力兴奋，因此使用了灾难取消方法。还讨论了执行器的大小，位置和输出幅度与控制效果之间的关系。当壳在三种主要模式的共振频率上激发壳时，进行了实验和模拟。结果表明，不同模式的受控振动品种的最小放大器。隔离，提出了一种方法来控制圆柱形壳系统的振动。圆柱体……更多的壳系统由中间的聚合物膜组成，两侧的一个压电膜组成。压电膜分为几个部分，其中一些作用为分布式执行器。在周期性兴奋下对壳振动的分析是通过模态膨胀方法进行的。控制器是基于H_*控制理论和模态分析结果设计的。使用设计的控制器进行了数值模拟和实验，结果表现出良好的一致性，以及该方法在抑制强制振动方面的有效性。最后，一项针对圆柱壳的振动控制的研究，使用分布式压电传感器和壳壁的分布式压电器和执行器。模态扩展方法用于估计系统的状态等效性。包括H_*控制理论和MU合成方法在内的可靠控制适用于在给定控制性能和稳健稳定性的情况下满足控制器的设计。当壳在受控模式的共振频率上激发壳时，进行了仿真和实验。结果显示了模拟和实验之间的良好一致性，以及使用分布式传感器和执行器的方法的有效性，以及H_*控制理论和MU合成方法。较少的