Examination of vibration control of linear oscillatory actuator

Linear oscillatory actuators (LOAs) are widely used in linear motor shavers, electric toothbrushes, and mobile phone vibrators as high‐speed oscillatory driving devices. The maximum amplitude of the motor is obtained at a resonant frequency that is determined from the spring constant and the mass of the motor. However, there is a problem with these actuators: the amplitude decreases sharply when the driving frequency differs from the resonant frequency in a mechanical vibration system with minimal damping. In this paper, we propose a control method for the resonant frequency in which the thrust, which shows the characteristics of a spring, is generated on the basis of the displacement of the mover and the damping factor, in which the thrust, which shows the characteristics of damping, is generated based on the velocity of the mover. The proposed method assures that the resonant frequency always corresponds to the driving frequency and that rapid changes in the amplitude are avoided. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 55–62, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21172     

A lightweight linear actuator with concentratedly placed stationary coils

This paper presents a novel lightweight linear actuator using permanent magnets and having its coils on the stator concentratedly. The rated force is 6 N, the stroke is 30 mm, and the weight is below 300 g owing to its unique structure. The machine is to be applied to, e.g., a pick‐and‐place actuator of tiny electronic parts, and the performance for the application is confirmed through experiments with a prototype. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 59–67, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20158     

Simple new ultrasonic piezoelectric actuator for precision linear positioning

This paper presents a new linear piezoelectric actuator for linear translation. The positioning stage driven by the actuator has a very simple and compact structure consisting of a linear guide and the linear piezoelectric actuator. The operation principle of the linear piezoelectric actuator is first described. Then, the characteristics of the positioning stage are investigated. Experiments indicate that the step size is adjustable and the minimum is 26?nm with an inertial mass of 100?g in the open-loop condition; the stage motion driven by the actuator is controlled to the target position plus or minus <1?μm within 330?ms for a traveling distance of 10?mm in the closed-loop condition.     

Static thrust analysis of a cylindrical moving-core linear oscillatory actuator

This paper considers materials for the movers, the volume ratio of the stator and of the mover, and the structure of the mover in a cylindrical moving iron-type linear oscillatory actuator (LOA) having a permanent magnet. As a result, we obtain the following:

• (1) the static thrust characteristics are evaluated on two movers: movers P and S are made of a permendur and a stainless steel, respectively. It is clarified that the static thrust of the mover P is 30 percent larger than that of the mover S;
• (2) it is suggested that the structure of the mover P should be improved to eliminate a “lump” in the static thrust-displacement curve due to the step on the mover, and which disturbs the smooth motion of the LOA.

     

运用静态反馈分析设计离散饱和线性系统

给出了控制饱和单输入状态反馈系统是全局渐近稳定还是区域渐近稳定的充分性条件,且对区域渐近稳定的情况计算其不变吸引椭球,运用Ricatti方程迭代法设计控制器以使所得椭球尽量大;对多输入控制饱和系统输出反馈系统,给出其吸引域的描述;最后用算例说明方法的有效性。     

Design, analysis, and control of a novel linear actuator

The main objective of this paper is to develop a linear actuator for an accurate position control with a high force-to-mass ratio. A novel configuration is developed that has a double-sided NdFeB stator and a printed-circuit moving armature. A design methodology is presented, which is based upon the finite-element method magnetic-circuit analysis, and a simulation software for performance predictions. The latter is developed in a VisSim environment. For design optimization, a new criteria are introduced. A hardware-in-the loop control technique is developed and applied to the designed motor. Micrometer position accuracy is achieved experimentally. It is shown that the computational and experimental performance values are in good agreement.     

Compact size ultrasonic linear motor using a dome shaped piezoelectric actuator

This paper presents original results obtained in the development of dome-shaped actuator for a linear motor application. The main structure of compact ultrasonic linear motor presented in this paper consists of three parts, which were an actuating part, a shaft and mobile element. The actuating part was fabricated by powder injection molding (PIM) process. The linear motion of new-type linear motor was operated by the principle of inertia displacement. The actuating part combined with clamping ceramic element can be realized by the central movement of dome-shaped piezoelectric actuator (DSPA), which has the maximum displacement of the up-and-down movement. The linear motor, where DSPA was 9.86?mm in diameter, 4.6?mm in curvature of radius and 0.4?mm in thickness, operated at 1^st resonance frequency. The dynamic characteristics of the motor was investigated by finite element method (FEM) and compared with experimental results. These results were in good agreement with that predicted by simulations.     

New multi-rod linear actuator for direct-drive, wide mechanical bandpass applications

In this paper, a new multi-rod linear actuator is presented. This actuator has been developed for high thrust density and wide mechanical bandpass applications. The multi-air-gap concept is first illustrated and explained. Its advantages are highlighted thanks to finite-element method optimizations. Next, the multi-rod prototype technology is discussed. Lastly, experimental measurements for prototype forces are provided.     

基于FOA-RBF的管状开关磁阻直线电机直接瞬时出力控制

以车辆主动悬架系统为应用背景,针对径向磁通的管状开关磁阻直线电机提出了一种基于果蝇算法优化径向基神经网络模型(FOA-RBF)的直接瞬时出力控制方法。利用台架测量得到的电机出力样本对FOA-RBF进行离线训练,完成电流、动子位置到出力的非线性映射,构造出基于FOA-RBF的出力观测器对电机出力进行实时在线估算,并与出力分配函数相结合,实现相邻两相出力目标值的动态调整,有效地抑制了出力波动并降低了各相电流峰值。该控制方法利用了FOA-RBF神经网络泛化和逼近能力强的优点,出力计算速度快、精度高,满足实时控制要求。基于台架实际测量的电机出力和电磁特性,结合运动方程在MATLAB/Simulink环境中构建了系统仿真模型,并对提出的控制策略进行了仿真验证。最后搭建实验平台对电机动态性能进行了测试,进一步验证了FOA-RBF出力估算和控制算法的有效性。     

Characteristics of linear actuator with semiclosed magnetic circuit excited by discharge current of capacitor

The simple structured linear actuator considered in this paper is based on the model, called the single-phase oscillating motor, proposed by Jayawant. Reports have already been made on the static and kinetic characteristics of the actuator of the model proposed by the authors for two cases considered and not considered the magnetic saturation when it was driven by an ac source. Although the theoretical procedure to calculate the characteristics is very simple, the calculated results in both cases have shown close agreement with the experimental ones. To improve the actuator for practical use, some methods will be considered and one of them is to use a dc source instead of an ac source. Using the charged capacitor as a dc supply, an instantaneous large current flows easily in the exciting coil in comparison with the case of an ac supply. In this paper, qualitative explanation of the ring motion and calculated results of the ring speed which have good agreement with experimental results are reported.     

Mission independent fault-tolerant control of heterogeneous linear multiagent systems based on adaptive virtual actuator

In this article, a fault-tolerant control (FTC) scheme for linear multiagent systems (MASs) subject to time-varying loss of effectiveness and time-varying additive actuator faults as well as external disturbance is investigated. The main objective of the proposed FTC approach is to keep the performance of an MAS after the occurrence of actuator faults similar to the healthy one. The envisaged adaptive virtual actuator for each agent does not require a separate fault detection, isolation, and identification unit nor does it require any information regarding the mission of the MAS. It is shown that the difference between the states of each agent before and after the occurrence of actuator faults can be made arbitrary small and the ultimate bounds of the state error are also obtained. Furthermore, it is shown that for constant actuator faults the state error of each agent converges to zero. Simulation results corresponding to a team of F-8 aircraft and a heterogeneous MAS with the different order demonstrate and illustrate the effectiveness of our proposed FTC scheme.     

Adaptive output feedback actuator failure compensation for a class of non‐linear systems

An adaptive compensation control scheme using output feedback is designed and analysed for a class of non‐linear systems with state‐dependent non‐linearities in the presence of unknown actuator failures. For a linearly parameterized model of actuator failures with unknown failure values, time instants and pattern, a robust backstepping‐based adaptive non‐linear controller is employed to handle the system failure, parameter and dynamics uncertainties. Robust adaptive parameter update laws are derived to ensure closed‐loop signal boundedness and small tracking errors, in general, and asymptotic regulation, in particular. An application to controlling the angle of attack of a non‐linear hypersonic aircraft dynamic model in the presence of elevator segment failures is studied and simulation results show that the developed adaptive control scheme has desired actuator failure compensation performance. Copyright © 2004 John Wiley & Sons, Ltd.     

Reluctance control magnetic suspension system—suspension system with permanent magnet and linear actuator

A new type of magnetic suspension system is proposed which uses a permanent magnet. In this system, the attractive force is adjusted by controlling the reluctance of the magnetic circuit. Since no electromagnet is necessary, this system is effective for saving energy and avoiding heat generation. The composition of this paper is as follows. First, the principle of this suspension system is explained and various types of magnetic circuits are introduced for reluctance control. Second, the possibility of one of them is examined from the viewpoint of linear control theory. Third, an experimental device is developed based on the proposed suspension method. The reluctance of this device is controlled by the air gap which is between the magnet and the suspended object, and which is adjusted by driving a permanent magnet by piezoelectric actuator. Experimental results support the theoretical predictions well.     

Investigation of omnidirectional piezoelectric actuator

A study of a novel design composite piezoelectric actuator for omnidirectional object positioning is given in the paper. The actuator consists of a vibrating disc with a small cylinder mounted at the centre and a piezoceramic disc. The cylinder magnifies resonant bending vibrations of the vibrating disc and transmits driving force to the slider. Electrodes of the piezoceramic disc cover all the surface of the bottom and are divided into four equal sectors. 2D motion and rotation of the slider is achieved depending on the excitation scheme of the electrodes. Numerical modeling based on the finite element method was performed to obtain resonance frequencies and modal shapes of the actuator and to calculate the trajectories of contact point’s movements under different excitation schemes of the electrodes. A prototype actuator was made and experimental outcomes of the oscillations of the working surfaces are given. Results of the numerical and experimental investigations are analyzed and discussed.     

Model‐free fault‐tolerant control approach for uncertain state‐constrained linear systems with actuator faults

This paper investigates the robust adaptive fault‐tolerant control problem for state‐constrained continuous‐time linear systems with parameter uncertainties, external disturbances, and actuator faults including stuck, outage, and loss of effectiveness. It is assumed that the knowledge of the system matrices, as well as the upper bounds of the disturbances and faults, is unknown. By incorporating a barrier‐function like term into the Lyapunov function design, a novel model‐free fault‐tolerant control scheme is proposed in a parameter‐dependent form, and the state constraint requirements are guaranteed. The time‐varying parameters are adjusted online based on an adaptive method to prevent the states from violating the constraints and compensate automatically the uncertainties, disturbances, and actuator faults. The time‐invariant parameters solved by using data‐based policy iteration algorithm are introduced for helping to stabilize the system. Furthermore, it is shown that the states converge asymptotically to zero without transgression of the constraints and all signals in the resulting closed‐loop system are uniformly bounded. Finally, two simulation examples are provided to show the effectiveness of the proposed approach. Copyright © 2016 John Wiley & Sons, Ltd.     

执行机构与控制装置的联接

舟山发电厂在对1×125MW机组进行分散控制系统DCS(DistributedControlSystem)改造后,由于执行机构与硬手操器联接时系统接口考虑不周引起错误的电气通路而导致电流异常,详细分析了其产生的原因并给出了解决方案。     

压电驱动器驱动电源设计

针对提高电源的输出质量、容性负载的响应速度等设计要求,设计了一种基于PA78的电压控制型压电陶瓷驱动电源。从理论角度研究了电压控制型驱动电源特点并初步制定了设计方案,以PA78高压功放作为核心器件,对驱动电源的核心电路、直流稳压电路及放电回路等进行设计。在此基础上,对驱动电源电路的稳定性、频响特性等关键性能进行研究。最后搭建了驱动电源测试系统,在容性负载情况下,对驱动电源的线性度、纹波电压等基本性能进行测试和分析,实验结果表明所设计的驱动电源满足设计要求。