压电作动器在基于声辐射模态的ASAC中的应用

控制作动器的选取和设计是实现主动结构声学控制的关键一环。利用压电材料的逆压电效应,选择矩形压电片作为控制作动器应用于基于声辐射模态的主动结构声学控制中,提出了基于声辐射模态的压电作动器主动控制策略,并得到了最佳控制电压的获取方法。以简支板为例,通过压电作动器控制效果分析,揭示了压电作动器控制的内在规律;通过与单点力控制效果的比较分析,验证了压电作动器控制策略的优越性。     

采用MFC压电作动器对复合材料悬臂板振动主动控制

针对复合材料层合悬臂板,在其上表面铺设压电纤维复合材料MFC作为作动器,同时在下表面对称铺设压电薄膜(PVDF)作为传感器,应用速度反馈控制方法研究其主动振动控制.运用Hamilton原理和假设模态法推导含多个MFC作动器的复合材料层合板的力电耦合结构运动方程,其中考虑了MFC作动器作为悬臂板附加质量及刚度的影响.基于模态控制力/力矩最大化的原则,将多对MFC作动器/PVDF传感器铺设在层合悬臂板前几个低阶模态应变最大的区域,通过算例得出结构受控前后的时域和频域响应以及各MFC作动器所需的控制电压曲线.讨论复合材料层合板纤维铺设角度不同情况下,作动器MFC铺设位置及压电纤维铺设方向的相应变化.     

智能结构的压电片位置优化及主动控制研究

采用压电陶瓷作为作动器,对柔性结构的作动器位置进行了优化设计并对其进行了振动主动控制研究.首先分析了压电结构振动主动控制的原理和方法;采用基于作动器的模态影响矩阵对压电片进行了优化布置,使压电片配置在控制效能最优的位置.在存在噪声和干扰的情况下对智能结构进行控制,采用LQG/LTR和H∞方法对结构进行控制,并对二者的控制效果作了比较.结果显示在加入噪声和干扰后,进行适当的处理,采用LQG/LTR和H∞方法都能达到很好的控制效果,只是鲁棒性有差别.     

不同作动器布局和时滞下柔性悬臂梁振动控制研究

由于压电作动器自身性能的限制,工程中可能需要使用多个压电作动器.本文研究了双压电作动器下柔性悬臂梁的时滞振动控制.研究发现,控制回路没有时滞时,双作动器在不同布局下都能对梁的振动实现等效控制,此时两个作动器输入电压成线性关系,该线性关系斜率与作动器分布位置相关.进一步地,针对有时滞情况,当改变作动器的布局和时滞,通过分段时滞状态反馈,系统仍能达到相同的控制效果.     

襟翼机电作动器的非线性跟踪控制器设计

针对存在未知扰动的民机襟翼机电作动器,为了实现位置跟踪控制,提出了一种新型的非线性连续鲁棒控制器.利用反向递推理论对非线性连续鲁棒控制器进行了设计.首先通过设计电流虚拟控制量,对未知机械扰动进行了补偿;其次,利用电流虚拟控制量,设计了控制电压,实现了对未知扰动信号的抑制.根据李雅普诺夫稳定性分析方法,论证了在所设计的控制器作用下,受控机电作动器能够实现对参考轨迹的全局渐进跟踪.仿真结果表明,改进控制器能够有效提高机电作动器的位置跟踪控制性能,控制效果优于PID控制.     

利用PVDF压电膜设计声辐射模态传感器

提出了一种新的聚偏氟乙烯(PVDF)压电传感器的设计方法测量板的前2阶声辐射模态伴随系数。结果表明:在中低频率,测量第一阶声辐射模态伴随系数,只需要在板布置两条PVDF传感器即可;测量第二阶声辐射模态伴随系数,可在板上布置多条传感器能得到比较精确的结果。同时,传感器测量的结果与理论相符,说明这种新型PVDF传感器的设计是可行的。     

轨道车辆车轮辐板阻尼层对其降噪效果的影响分析*

采用模态叠加法求得阻尼车轮导纳特性,利用已建立的轮轨滚动噪声预测模型,以轮轨表面粗糙度为激励,分析了辐板阻尼层与其厚度对阻尼车轮振动与声辐射特性的影响规律.首先,建立了阻尼车轮三维实体有限元模型,采用Block Lanczos方法计算车轮模态特征;其次,利用模态叠加法求得车轮在单位荷载激励下的频响函数;然后,利用虚拟激励法求得车轮在粗糙度谱激励下的频域振动特性;最后,依据车轮动态响应通过解析的方法求得车轮声辐射频域特性.计算结果表明:(1)车轮辐板敷设阻尼层对车轮1000Hz以下频率的振动与噪声的抑制作用不明显,而对车轮1600Hz以上的高频振动具有良好的抑制作用;(2)车轮辐板双侧敷设阻尼的降噪效果优于单侧阻尼;(3)阻尼层可以有效抑制车轮振动,且车轮辐板敷设阻尼层厚度越厚效果越明显.     

飞机力纷争均衡分析和研究

针对某型号飞机余度作动系统力纷争现象,分析其产生的原因,建立力纷争均衡算法,以缓解力纷争现象,达到同舵面不同作动器间负载均分的目的。通过建立力纷争均衡的控制系统仿真模型,与物理试验结果作比较,计算力纷争均衡指令,对原舵面位置控制指令产生偏置信号,以均衡同一舵面不同作动器的两腔压差。运用仿真分析和物理试验相结合的方法对解决多余度作动系统力纷争现象的方法进行进一步探究,在建立原理性试验平台的同时,也为系统力纷争均衡控制律设计提供更可靠的试验评定依据。     

静水压与阻尼覆盖层对圆柱壳声辐射的影响

基于有限元和边界元法,对水下结构的耦合振动和声辐射进行了数值计算。首先利用ANSYS软件建立声振模型,并计算流固耦合振动;再利用SYSNOISE软件计算辐射声场,分析了水深及阻尼材料对加肋圆柱壳水下振动和声敷设的影响。结果表明：研究圆柱壳的水下声辐射时必须考虑静水压力的作用,阻尼材料能够有效降低结构的振动及声辐射。为实艇降噪治理方案的设计及效果预估提供参考。     

微致动器在流动控制中的应用研究

基于MEMS技术,研制了一种微气泡型致动器.对前缘布置有微致动器的三角翼进行了数值模拟和风洞实验,结果表明:微致动器可以改变三角翼前缘的旋涡流状态,扰动边界层,改变三角翼前缘分离涡位置,合理布置微致动器可以获得一定的滚转力矩,利用微致动器可以进行流动控制,进而改变飞行器的动力性能.     

Observer‐based cooperative distributed fault‐tolerant model predictive control with imperfect network communication and asynchronous measurements

Intermittent actuator and sensor faults tolerant are simultaneously considered in a distributed control system with imperfect communication network. The asynchronous measurements of different output variables in one sampling period are synchronized through a novel two‐stage model‐based projection method. Different from centralized control network, in both layer‐to‐layer and in‐layer communication, the packet delay, loss and disordering are corrected by the predicted data from model predictive control. Moreover, a completely distributed state observer is established for both system states and sensor faults problem with bounded noise uncertainties. For the intermittent actuator faults, actuator plug‐and‐play design methods based on model predictive control has been introduced, making the actuator faults estimation omitted. The distributed stability conditions are derived for the proposed fault‐tolerant controller, and the online feasibility is explained in detail. Numerical simulation is given to verify the design procedure.     

微测辐射热计的噪声分析

以电阻型微测辐射热计作为基本模型,分析其在电压偏置下的噪声特性.针对微测辐射热计中的约翰逊噪声、1/f噪声与辐射噪声,着重探讨了微测辐射热计的偏置电压、电阻、噪声带宽等参数对其噪声和信噪比的影响,并根据分析仿真结果,提出了三种增加微测辐射热计信噪比的方法.     

An Adaptive and Optimized Switching Observer for Sensorless Control of an Electromagnetic Valve Actuator in Camless Internal Combustion Engines

In this paper, the design and operation of a special electromagnetic actuator as a variable engine valve actuator are presented. Further, this paper describes a feasible approximated velocity switching estimator based on measurements of current and input voltage to achieve sensorless control. The proposed concept allows a reduced‐order observer to be conceived and yields a specific control strategy with an acceptable performance. In general, this approach represents a viable strategy to build reduced‐order observers for estimating the velocity of systems through the measurement of input current and voltage. The robustness of the velocity tracking is explored using a minimum variance approach. The effect of the noise is minimized, and the position can be achieved through an adaptive and optimized structure by combining this particular velocity estimator and an observer based on the electromechanical system. Position control is achieved through an inversion of the model. This approach avoids a more complex structure for the observer and yields an acceptable performance as well as eliminating bulky position‐sensor systems. In addition, a control strategy is presented and discussed. Computer simulations of the sensorless control structure are presented in which the positive effects of the observer with optimized parameter setting are visible in the closed‐loop control.     

新型动磁式直线振荡执行器的动子位移自传感

针对一种新型无内定子动磁式直线振荡执行器,在建立其机电系统数学模型的基础上,提出一种基于全维状态观测器的动子位移自传感算法。通过对执行器输入电压和输出电流信号的处理和计算来估算动子位移。仿真和实验结果均表明:在变压变频控制方式下,该算法能实现不同电气驱动频率下的动子位移自传感;采用该算法进行行程估算的绝对误差最大值为0.32 mm,相对误差最大值为2.6%。此算法可以满足直线压缩机和直线泵类负载的变行程控制要求。     

Multivariable adaptive control of instabilities arising in jet engines

We consider a class of MIMO LTI models with uncertain resonant modes and time delays, which are common in control of instabilities arising in jet engines. With uncertain delays preventing the use of model reference adaptive control, we develop an adaptive MIMO pole placement scheme for the system. We use indirect adaptation, estimating a small number of physical parameters from a nonlinearly parametrized plant. To address the highly noisy environment in jet engines we introduce the deadzone in the adaptation law and present simulations that successfully stabilize the system in the presence of noise and severe actuator saturation.     

基于多元时间序列分析的控制系统执行器故障诊断方法研究

为提高控制系统执行器故障实时诊断的准确率,该文提出一种基于多元时间序列分析的控制系统执行器在线故障诊断方法。首先分析了控制系统执行器故障机理,确定了表征执行器故障的关键信号;其次采用执行器历史数据,建立了时间卷积网络(TCN)在线预测模型,对执行器多通道信号进行在线预测;随后通过长短期记忆网络(LSTM)对多通道残差信号建立了故障分类模型;最后以燃气轮机控制系统执行器半物理试验平台中的电液执行器为例进行了多次重复试验验证。结果表明,基于TCN网络的在线预测模型相比传统循环神经网络(RNN)预测误差较小;基于LSTM网络的故障分类模型准确率较高;通过LSTM网络对多通道残差信号进行故障分类,比对原始故障数据分类故障准确率更高。     

自传感介电弹性体执行器的动力学设计及应用

本文提出了一种传感与作动一体化的介电弹性体（DE）软执行器,可用于薄膜结构形面变形的同步测量和控制.首先,建立DE软执行器电致驱动过程的动力学模型,描述其力电耦合行为.其次,通过开展动态作动实验,辨识该动力学模型的参数.第三,分析不同参数对作动器动态响应的影响,以理解其基本动力学特性.第四,建立DE软执行器自传感过程的简化电路模型,并对其电学参数与位移之间的关系进行实验标定.最后,开展平面薄膜结构的形面位移自适应调整实验,并设计相应的控制策略.实验结果表明,该DE软执行器在作动和传感方面均具有较高精度.因此,其在构建高精度空间薄膜天线方面具有较好的应用前景.     

基于应变式传感器的压电陶瓷定位系统设计

基于压电陶瓷驱动的纳米扫描和定位系统,是原子力显微镜系统的关键部件。本文设计了基于电阻式应变传感器(SGS）的压电陶瓷微纳米位移定位系统。该系统在硬件上采用仪表放大器对SGS应变信号进行RF滤波、放大、模拟滤波处理得到与压电陶瓷位移变化线性相关的电压信号,该信号由高精度AD采集,并通过控制器输出到上位机软件MATLAB中进行噪声分析、FIR数字滤波去噪、线性度分析。实验结果表明,该位移检测系统输出电压噪声峰峰值小于0.5mV,输出非线性误差小于0.06%,可实现2nm的位移分辨率。该定位系统可以应用于原子力显微镜的开发中。     

Optimal fault-tolerant control for Markov jump power systems with asynchronous actuator faults

Communication problems in the sensor-to-controller and controller-to-actuator channels can cause both the controller and actuator to run asynchronously with the original system in different operating modes. This paper investigates an optimal fault-tolerant control approach for Markov jump power systems (MJPSs) with asynchronous controller and actuator. Firstly, an asynchronous controller is proposed to deal with incomplete information (i.e., system modes) transmission in the sensor-to-controller channel. Secondly, a new asynchronous actuator faults model is constructed to simultaneously represent the two partial losses, of modes information in the controller-to-actuator channel, and of control effectiveness (LoCE) caused by actuator faults. Under this framework, two related hidden Markov models (HMMs) are formed, which reveal that both the controller and actuator are asynchronous with the controlled system in different modes. By using Lyapunov and optimal approaches, sufficient conditions are derived to ensure that MJPSs are mean square stable with an optimal guaranteed cost. Finally, Monte Carlo simulations are used to verify the effectiveness of the proposed control method.     

Charge control of parallel-plate, electrostatic actuators and the tip-in instability

Controlling the charge, rather than the voltage, on a parallel-plate, electrostatic actuator theoretically permits stable operation for all deflections. Practically, we show that, using charge control, the maximum stable deflection is limited by 1) charge pull-in, in which the actuator snaps due to the presence of parasitic capacitance and 2) tip-in, in which the rotation mode becomes unstable. This work presents a circuit that controls the amount of charge on a parallel-plate, electrostatic actuator. This circuit reduces the sensitivity to parasitic capacitance, so that tip-in is the limiting instability. A small-signal model of the actuator is developed and used to determine the circuit bandwidth and gain requirements for stable deflections. Four different parallel-plate actuators have been designed and tested to verify the charge control technique as well as to verify charge pull-in, tip-in, and the bandwidth requirements. One design travels 83% of the gap before tip-in. Another design can only travel 20% of the gap before tip-in, regardless of whether voltage control or charge control is used.