Microvibration Control System Research Articles

Multi-frequency micro-vibration control with hybrid adaptive control algorithm

As a popular adaptive algorithm for active vibration control (AVC), filtered-x least mean square (FxLMS) algorithm sometimes fails to suppress multiple narrowband disturbance. To control multi-frequency structure vibration, parallel-form FxLMS algorithm can be employed. However, the conventional parallel-form FxLMS does not perform well in the situation of disturbance frequency mismatch and wideband measurement noise. For this issue, the majority of the improvement approaches are based on adaptive frequency estimator. It increased the computational burden of the parallel-form FxLMS algorithm. Therefore, taking the advantage of feedback control, a hybrid adaptive control for AVC is proposed in this paper. And the “posterior” residual error is adopted for better robustness. The convergence analysis of the hybrid AVC algorithm is given. Co-simulations with ADAMS and SIMULINK are implemented to verify the effectiveness in micro-vibration control system. Some comparison experiments are implemented in a micro-vibration AVC experimental system for several typical disturbances. Experimental results confirm the feasibility and effectiveness of the proposed algorithm.

Study on Active Micro-vibration Isolation System with Linear Motor Actuator

An active micro-vibration isolation control system with linear motor actuators has been proposed and studied. The system is supported by the air springs and symmetrically placed linear motor actuators. A mathematical model of the micro-vibration isolation platform is established, and the optimal control algorithm is designed for isolating vibration system. Simulation and experiment is carried out to verify the effectiveness of active micro-vibration control system. The results demonstrate that the proposed micro-vibration control system has good isolation performance and the linear motor can be used as the active actuator.

Control–structure interaction for micro-vibration structural control

The giant magnetostrictive actuator (GMA) is a typical actuator used in micro-vibration control applications. Research in the area of micro-vibration control has been conducted, but the effects of control–structure interaction have not been considered in most of the previous studies. Only hydraulic actuator and linear motor models have been developed to investigate actuator–structure interaction. To investigate the role of control–structure interaction (CSI) with the new GMA and multi-degree-of-freedom (MDOF) coupling platform system for micro-vibration control, computational models considering the interaction between the GMA and structure are developed in this paper. The models show that the dynamics of the GMA and the structure are tightly coupled. The model is further verified through experiments. Numerical results of a control study in which the multi-degree coupling platform system does and does not consider CSI are compared. The results demonstrate that consideration of the CSI and the dynamics of the GMA can improve the performance of a controller significantly. Consideration of this interaction and the dynamics of the GMA is essential when modeling a micro-vibration control system.

Application of Active Micro-vibration Control System using a Giant Magnetostrictive Actuator

In various leading-edge technology areas, such as semiconductor manufacturing, the requirement for micro-vibration control is increasing. The authors have developed an active six-degrees-of-freedom (6-DOF) micro-vibration control system using an off the shelf, giant magnetostrictive (GMS) actuator. The efficiency of the active micro-vibration control system using a GMS actuator has been verified through several control experiments. However, the active micro-vibration control approach has not previously been applied to actual precision measuring equipment. Therefore, the control performance of such systems has not been verified on a practical application. In this study, an active 6-DOF micro-vibration control system using GMS actuators is developed and applied to buildings in order to provide micro-level-vibration-free space for a focused ion beam (FIB). The outline of the system, the design of the control system, and the results of experimental verification are described. In this application of the active micro-vibration control system, the design of the active micro-vibration control system is carried out taking several factors into consideration. Vibration measurements made after adjusting the micro-vibration control system confirm that the table satisfies the specified requirement and that a clear FIB image is obtained under high-magnification observation.

Development of active six-degrees-of-freedom micro-vibration control system using hybridactuators comprising air actuators and giant magnetostrictive actuators

In recent years, there has been an increasing demand for micro-vibration free space fromindustrial and scientific organizations. In response to this demand, several activemicro-vibration control systems utilizing various types of actuators have been developedand applied in various environments and to a number of machines. The authors havedeveloped an active micro-vibration control system with six degrees of freedom using giantmagnetostrictive (GMS) actuators and actually have applied it to an FIB (focused ionbeam).In general, a GMS actuator has a quicker response time and bigger displacementcharacteristics at higher frequencies than an air actuator. Therefore, we have developed ahybrid actuator that consists of a GMS actuator and an air actuator. Its main feature isthat the two actuators are arranged in parallel. Ideally, such a hybrid actuatorwould have the merits of both component systems. Through experimental testson the hybrid actuator and simulation analysis on the uni-axial micro-vibrationcontrol device using the hybrid actuator, we have shown that this is the case.Following this successful result, we have developed an active 6-DOF micro-vibration controlsystem using hybrid actuators. This paper presents an outline of the active 6-DOFmicro-vibration control system, the hybrid actuator used, and the design strategy of thecontrol system. Results of control experiments under various disturbances are described.Through these results, it is verified that an active 6-DOF micro-vibration control systemusing hybrid actuators controls vibration more effectively than use of air actuatorsalone. This good performance is realized by the efficiency of the hybrid actuator,which is attributed to the collaboration of the air actuator and GMS actuators.

Comprehensive Active Microvibration Control Systems Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

Active microvibration control is expected to be applied to floors and even entire buildings of precision manufacturing facilities to meet requirements for more perfect vibration-free environment in the facilities. It is desirable that such facilities are effectively protected from earthquake attacks by using seismic isolation. For base-isolated precision manufacturing facilities, comprehensive active microvibration control systems were studied to control both of microvibrations born in the inside due to equipment and human walks and microvibrations coming from the outside due to ground vibrations and winds. A base-isolated 2-story building model of a 3m×5m×4mH external size and a 6.9t total mass was used for experiments, in which 4 multistage rubber bearings and a viscous shear damper were installed for the seismic isolation, while 20 piezoelectric actuators were attached to the columns and the beams and 8 piezoelectric actuator units were installed in the seismic isolation layer for the active control. The tests showed that the system consisting of the passive base-isolation system and the piezoelectric actuators attached to the columns and the beams could most effectively control the three-dimensional microvibrations due to the external and the internal disturbances.

Comprehensive Active Microvibration Control System Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

Comprehensive Active Microvibration Control System Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

Active Microvibration Control System Using Magnetostrictive Actuator for Surgical Microscope of Suspension Type

It has been a problem in some hospitals that operations using surgical microscopes of suspension type become more difficult due to microvibrations of the microscopes caused by human walks and building equipment such as air conditioning machines. For a practical solution to it, an active microvibration control system was developed, in which magnetostrictive actuators were used because of their large stiffness. A control law based on a model matching method was used to control of microvibrations of the microscopes having various dynamic characteristics corresponding to their attitudes. Tests showed that the microvibration control system using the control law was effective. Furthermore an active-passive switching law was developed to manage large vibrations of the microscopes due to doctors handling of them. Tests showed that the microvibration control system was effective and reliable enough for real application.

Comprehensive Active Microvibration Control System Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

Comprehensive Active Microvibration Control System Using Piezoelectric Actuators for Base-Isolated Precision Manufacturing Facilities

244 天井懸架型手術顕微鏡のアクティブ微振動制御装置

It has been a problem in some hospitals that operations using surgical microscopes of suspension type become more difficult due to microvibrations of the microscopes caused by human walks and building equipment such as air conditioning machines. For a practical solution to it, an active microvibration control system was developed, in which magnetostrictive actuators were used because of their large stiffness. A control law based on a model matching method was used to control of microvibrations of the microscopes having various dynamic characteristics corresponding to their attitudes. Tests showed that the microvibration control system using the control law was effective.

Development of a uni-axial hybrid actuator using the combination of an air actuator and a giant-magnetostrictiveactuator

Active microvibration control systems have beendeveloped and applied in a practical manner. Various types ofactuator, for example an air actuator, a linear movingactuator, a piezoelectric (PZT) actuator and a giant-magnetostrictive (GMS)actuator, have been used. In general, all actuators have bothmerits and demerits, so an optimal actuator should be selected based on the objective performance and the conditions of usage.We developed an active 6-DOF microvibration control systemusing GMS actuators. It has been speculatedthat the GMS actuator is suitable as adisplacement actuator for an active microvibration control. Thereasons for this are that it has better durability andreliability compared with a PZT actuator, and alsoits response to an input signal is much faster than an airactuator. However, the demerits of the GMSactuator come to light through practical application of thesystem. The displacement property tends to decrease with increase in the magnitude of forced axial load, and it cannot generate a sufficient displacement in a low frequency range.Therefore, in order to improve the above-mentioned demeritsrelated to a GMS actuator and an airactuator, we have developed a new type of hybrid actuator usinga GMS actuator and an air actuator. The twoactuators are arranged in parallel. This structural featureenables the new hybrid actuator to make up for both of the singleactuators' demerits. Consequently, it has become possible tocontrol displacement in the wider frequency range of0.1-100 Hz and to generate a maximum displacement of more than1 mm.This paper presents an outline of the experimental new hybrid actuator, the result of a dynamic characteristic test of theactuator and simulation analysis on the uni-axialmicrovibration control device using the hybrid actuator.Through these results, the higher performance achieved by the newly developed hybrid actuator isverified.

K-2311 超磁歪アクチュエータによる免震された精密生産施設のアクティブ微振動制御(J03-1 知的要素技術(1))(J03 知的材料・構造システム)

In the contries, where the earthquakes often happen, like Japan buildings should be equipped with Isolation system, especially for precision manufacturing facilities. And the isolation system is effective not only inside but also outside the buildings. Here, we develop high-performanced Active Microvibration Control System for Base-Isolated precison manufacturing facilities, using Magnetostricgtive Actuators.

Development of active six-degrees-of-freedom microvibration control system using giant magnetostrictive actuators

An active six degrees-of-freedom microvibration control system using giant magnetostrictive actuators is developed in order to realize a microvibration-free space for precision instruments which hate vibration. A giant magnetostrictive actuator is suitable as a displacement actuator for active microvibration control, because it is both compact and durable and also its response against input is fast and reliable. The developed device consists of a table, six air springs, eight magnetostrictive actuators and six accelerometers on the table. Four actuators are set in the horizontal directions, and another four in the vertical direction. Since air springs and actuators as a unit of vertical support system are arranged in parallel, readjustment of the system is quite easy, even when the operating load on the table is changed. The dimensions of the table are 2000 mm length, 1400 mm width, 230 mm height and a weight of about 2 tons. The operating load on the table is 2 tons. A giant magnetostrictive rod is 6 mm in diameter and 50 mm long. The actuators operate within the stroke range of ±25 µm. A feedback control strategy using only six components of table acceleration on the table is adopted and the controller is designed by a model matching method. The obtained control performance of the system through two vibration control tests can be summarized as follows (1) Root-mean-square values of the table accelerations under micro-tremor are reduced to one-third to one-tenth of the floor accelerations, and kept less than 0.008 cm s-2. (2) Induced vibrations by impacts acting on the table disappear in less than 0.05 s.

Microvibration Control of Surgical Microscopes with Active Dynamic Vibration Absorbers.

It has been a problem in some hospitals that operations using surgical microscopes for brains and eyes bacome more difficult due to microvibrations of the microscopes caused by human wolks and building equipment such as air conditioning machines. For a practical solution to it, a microvibration control system was developed, in which an active dynamic vibration absorber using a small mass of 0.34 kg driven by an electromagnet and an accelerometer were collocated for vibration control in each direction. The system was attached on the point of the arm of the microscope. A direct velocity feedback control law was developed for the microscopes having various dynamic characteristics corresponding to their attiudes. Furthermore an active-passive switching law was developed to manage large vibrations of the microscopes due to doctors' handling of them. Tests showed that the microvibration control system was effective and reliable enough for real application.

Passive and active microvibration control for very high pointing accuracy space systems

This paper presents the results of a two-year proof-of-concept program to prepare for the foreseen needs to master microvibrations on-board high pointing accuracy platforms, through the design, prototyping and experimental validation of four microvibration control systems: (1) an elastomer-based passive isolator for six degree-of-freedom isolation of a disturbance source (reaction wheel or mechanical cooler). Attenuation performance exceeding 20 dB above 25 Hz and 40 dB above 50 Hz has been demonstrated. (2) A passive vibration damping system, based on distributed piezoceramic wafers connected to a dissipative electrical circuit. Such simple, standalone devices are shown to have interesting applications (up 20 dB attenuation) when applied to the damping of a local flexible mode with concentrated strain energy. (3) Active damping with two-dimensional smart structures by using positive position feedback on pairs of collocated piezo-electric wafers used as sensors and actuators. Modal damping from 10 to 20 dB on the best controlled modes has been demonstrated, but some less controllable modes remain essentially undamped. (4) A centralized anti-phase control scheme operating on distributed sensors and actuators to compensate for stationary harmonic disturbances. The sensors are accelerometers and the actuators piezoelectric wafers or active struts equipped with a stack of piezoceramic wafers. The harmonic disturbance (for instance a reaction wheel unbalanced force) is estimated and compensated, with demonstrated attenuation from 30 to 40 dB. Follow-on activities in the domain are focused on the development of flight prototypes of the two active control concepts, for validation through on-orbit experimentation.

Intelligent Material and Fluid Systems. Large Scale Active Microvibration Control System Using Piezoelectric Actuators Applied to Semiconductor Manufacturing Equipment.

This paper verifies the performance of the active microvibration control system using piezoelectric actuators with a table length of 3 m, a width of 1.8 m and a weight of 4000kg applied to large-scale semiconductor manufacturing equipment whose microlithographic accuracy was actually degraded due to the constant vibration. The mounted equipment was the integral-design semiconductor manufacturing equipment weighting 2600 kg. The controller was designed by a method dependent on the normalized coprime factor plant model in the preceding study used to prevent the elastic vibration of the equipment and table from causing the spillover phenomena of the control system. For the frequency-forming algorithm, the model matching method and the H∞ method were employed. As a result of this system's application, the microlithographic accuracy of the manufacturing equipment could be improved from about 2μm (before application) to an intrinsic value of nearly 0.1 μm.

テーブルの弾性振動を考慮したアクティブ微振動制御手法の研究

This paper presents a robust control method for a microvibration control system with elastic vibration of a table. In order to avoid the spillover phenomena, reduced-order mathematical models, which include higher modes, are used in this design technique. The feedback controller is derived by using the generalized model-matching method described in this paper. The system uses a 453-kg, 2.0 x 1.4-meter aluminum table as the vibration isolation object, being supported in 10 places (six vertical and four horizontal) by piezoelectric actuators. Rubber supports are installed between the table and the actuators. In the design technique, the overall system is divided into modal systems with the control system for each being independently designed. Experimental results are also presented.

Active 6 DOF Microvibration Control System Using Giant Magnetostrictive Actuator.

Active microvibration control systems are becoming necessary in high-technology fields such as semiconductor manufacturing. In this study, an active 6 DOF microvibration control system using a giant magnetostrictive actuator was developed. The actuator consisted of a giant magnetostrictive rod of a 50mm length and a 6 mm diameter surrounded by a driving coil. A control law was adopted to provide almost the same performance as that of sky-hook systems by using only absolute acceleration, instead of achieving feedback of absolute displacement and velocity. Through vibration control experiments, it was shown that performance of the system was sufficient for implementation, including isolation performance against micro floor motion, damping performance against direct disturbance, and control system robustness.

Study on 6DOF Microvibration Testing Device Using Piezoelectric Actuators.

Microvibration control is becoming more important in high-technology fields such as semiconductor manufacturing, and influence of microvibration on precision machines is increasing. However, microvibration sensitivities of these machines cannot be measured using conventional vibration testing devices. In this study, using an active 6DOF microvibration control system with piezoelectric actuators, feasibility of a microvibration simulator is discussed. A control method is proposed based on the model matching method, which achieves almost the desired frequency characteristics using only absolute acceleration. Experimental studies are conducted with satisfactory results in isolation performance against micro-ground motion, and servo performance for various reference inputs.

Active Micro-Vibration Control System Using Both Air Springs and Magnetic Bearings. 2nd Report. Isolation Performances Using H.INF. Control and Disturbance Cancellation Control.

In this study, we apply digital control to a micro-vibration isolation system using both air springs and magnetic bearings. We design two isolation control systems : a disturbance cancellation control system consisting of both the feedback and the feedforward control loops, and an H∞ control system designed by applying the solution of the H∞ 4 block problem. We first compare the two isolation systems through by means of simulation. The calculated results show that both systems can achieve excellent isolation performance. Also it is known that the disturbance cancellation effect can be accomplished by H∞ control, and the H∞ control system is stable against variations of the loading weight on the isolation table. Moreover, experiments using DSP (digital signal processor) are performed on the actual isolation system. The experimental results are almost the same as the simulated ones, and the effectiveness of H∞ control is confirmed.