Active noise control using a distributed mode flat panel loudspeaker

A flat panel distributed mode loudspeaker (DML) has many advantages over traditional cone speakers in terms of its weight, size, and durability. However, its frequency response is uneven and complex, thus bringing its suitability for active noise control (ANC) under question. This paper presents experimental results demonstrating the effective use of panel DML speakers in an ANC application. Both feedback and feedforward control techniques are considered. Effective feedback control with a flat panel speaker could open up a whole range of new noise control applications and has many advantages over feedforward control. The paper develops a new control algorithm to attenuate tonal noise of a known frequency by feedback control. However, due to the uneven response of the speakers, feedback control is found to be only moderately effective even for this narrow-band application. Feedforward control proves to be most capable for the flat panel speaker. Using feedforward control, the sound pressure level can be significantly reduced in close proximity to an error microphone. The paper demonstrates an interesting application of the flat panel in which the panel is placed in the path of sound and effectively used to block sound transmission using feedforward control. This is a new approach to active noise control enabled by the use of flat panels and can be used to prevent sound from entering into an enclosure in the first place rather than the traditional approach of attempting to cancel sound after it enters the enclosure.     

and feedforward and feedback compensators for acoustic isolation

This paper investigates through numerical simulations the limits of performance for a class of feedforward and feedback compensators used for structural acoustic isolation, where the emphasis is on controlling the structural vibration that is responsible for the sound radiation. The proposed designs aim to attenuate the sound pressure transmitted through a double panel system filled with absorption material. The controller must reduce the noise radiated through the back panel when the front panel is excited by an external force that causes structural vibration. A point moment simulating a piezoelectric patch attached to the back panel is the actuator. In the feedforward setting, the pre-filter assumes full information of the exogenous disturbance. On the other hand, the feedback designs assume full information of the state. The and norms are the optimality criteria used for both the filter design and the control design. All four designs are cast in the linear matrix inequality framework and incorporate parametric uncertainties described by a bounded convex polyhedral domain. It is shown that the performance of the feedforward and the feedback compensators are equivalent when model uncertainties are not taken into account. Otherwise, considering uncertainties, the feedback compensators have a more robust behavior.     

高速弹性连杆机构振动的复模态主动控制研究

应用 Hamilton虚功原理 ,建立了含有压电元件的弹性机构振动主动控制有限元模型。运用复模态理论 ,研究了机构的独立模态振动主动控制问题 ,给出了一种简便的包含状态反馈和干扰前馈的混合主动控制技术。针对一曲柄摇杆机构 ,进行了动态分析和主动振动控制的数值仿真。计算结果表明 ,本方法可以有效地控制系统的弹性振动     

具有迟滞和蠕变特性压电作动器的模糊自适应逆控制方法

针对具有迟滞和蠕变特性的压电作动器非线性模型,提出了一种前馈控制和反馈控制相结合的自适应模糊逆控制方案。在前馈控制器中压电作动器的迟滞和蠕变非线性特性的逆模型由自适应模糊逻辑系统近似;在反馈控制器中比例控制器用来调节压电作动器的输出误差。该方法可以实时补偿压电作动器的迟滞和蠕变特性,减少作动器跟踪误差。仿真计算结果表明了该方法的有效性。     

Adaptive feedforward control of ionic polymer metal composites with disturbance cancellation

Ionic polymer-metal composites (IPMCs) are promising candidates in various sensing and actuation applications due to their light weight, large bending, and low actuation voltage requirements. However, IPMCs are still in the early stage of development, and their bending response can vary widely depending on various factors such as fabrication process, water content, temperature, and contact with electrodes. To control IPMCs in a predictable manner and to minimize the effects of plant uncertainty and external disturbances, a precise and robust control scheme is required. In the present work, a three-part adaptive feedforward control architecture is employed for IPMC deflection control. First, adaptive identification is performed to identify changes in the dynamic behavior over time and in the input voltage using a gradient descent method. Second, an adaptive feedforward controller is implemented to control the dynamic response of the plant, where the IPMC displacement is observed and is used to adjust the parameters of the controller. Third, noise and disturbance cancelling is performed using an additional adaptive canceller, which does not affect the system dynamics. Our results show that the adaptive identification and feedforward controller with disturbance cancellation using the gradient descent method provides accurate tracking performance under plant variation and disturbance. Especially, the fast convergence speed of the proposed technique makes it practical for online control.     

变量泵源阀控系统的前馈自适应控制方法

变量泵源导致系统开环增益下降和动态变化,传统的反馈控制和串联校正很难使此类系统跟踪精度达到要求应用复合控制方法,可以对开环增益变化进行有效补偿,提高跟踪控制精度。运用MCS-96系列单片机技术、反馈控制、前馈控制和自适应控制原理,开发设计了数字控制器,实现了对系统的前馈自适应数字控制。试验研究结果表明,前馈自适应控制是实现变量泵源阀控系统高精度跟踪控制的有效方法。     

基于CMAC网络的主动隔振控制技术

针对主动隔振系统存在非线性,提出一种基于CMAC神经网络控制器的主动控制方法。由于系统的次通道使得控制器参数无法直接利用振动误差信号来调整,提出一种改进的同时扰动自适应算法,并证明该算法在数学期望上是一种随机梯度法。针对系统的非线性情况进行了仿真和试验研究,结果表明:与传统的FXLMS自适应前馈控制方法相比,所提出的方法对于存在非线性的周期性振动的隔振效果明显。     

惯性稳定平台自适应前馈控制

结合反馈控制提出了一种自适应前馈控制方法来提高惯性稳定平台稳定控制的指令跟踪性能。应用子空间辨识算法,由输入输出数据辨识稳定平台动态模型的状态空间描述;采用频域回路成型方法设计反馈回路控制器,用于抑制外部扰动。应用递推最小二乘(RLS)自适应滤波器构建反馈控制回路逆模型,构造指令信号的全通特性,提高指令跟踪能力。针对不同的指令信号进行跟踪实验,验证了自适应前馈控制方法的有效性。实验结果表明:提出的自适应前馈方法对阶跃指令响应快,超调量可由反馈控制的30%降低至4.5%,对30 Hz正弦信号的响应幅值无衰减,相位滞后由反馈控制的90°降低至54°。得到的结果显著提高了系统的暂态性能,控制性能优于单独的反馈控制回路。     

考虑负载扰动的电液转向系统控制研究

针对农机的电液伺服转向系统,为了克服转向力对系统的影响,提高在各种路况下的跟踪精度,设计了一种基于负载力观测器的前馈和最优状态反馈控制复合控制策略。先采用Luenberger观测器对负载力进行在线估计,然后用线性二次型调节器（LQR）得到系统线性最优反馈控制律,最后把观测到的负载力前馈到系统输入来消除负载力的影响,提高伺服系统精度。仿真和试验结果表明,所设计的负载力观测器能迅速地跟踪实际值,基于观测器的前馈和最优状态反馈复合控制策略具有较高的跟踪精度和抗负载干扰能力。     

Load speed regulation in compliant mechanical transmission systems using feedback and feedforward control actions

The problem of controlling the load speed of a mechanical transmission system consisting of a belt-pulley and gear-pair is considered. The system is modeled as two inertia (motor and load) connected by a compliant transmission. If the transmission is assumed to be rigid, then using either the motor or load speed feedback provides the same result. However, with transmission compliance, due to belts or long shafts, the stability characteristics and performance of the closed-loop system are quite different when either motor or load speed feedback is employed. We investigate motor and load speed feedback schemes by utilizing the singular perturbation method. We propose and discuss a control scheme that utilizes both motor and load speed feedback, and design an adaptive feedforward action to reject load torque disturbances. The control algorithms are implemented on an experimental platform that is typically used in roll-to-roll manufacturing and results are shown and discussed.     

Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model

In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller.     

FXLMS算法用于压电柔性结构多通道振动控制

以模拟太空帆板的压电机敏柔性结构为实验模型,针对结构振动响应主动控制技术需求,着重分析了多通道自适应滤波前馈控制方法及其FXLMS算法实现,以及受控通道模型参数辨识策略,并给出了详细的控制器设计结构图.针对实验模型对象设计、结构模态特性分析、压电元件优化配置、实验平台开发构建、相关软硬件测控环境、实验过程描述与结果分析验证,给出了研究思路与方法过程分析;进行了结构振动响应多通道主动控制实验并取得了良好的控制效果.结果表明,该控制器结构设计与自适应算法有效,为航天柔性结构振动响应分布式多通道控制提供了方法探索思路.     

基于类神经网络的磁流变主动振动控制研究

以类神经网络为基础进行磁流变主动振动控制,针对隔振系统自然频率与负载干扰记性振动抑制进行了研究,并分别利用回馈与前馈2种控制模式进行主动控制研究,其目的是为了降低系统自然频率共振与负载干扰的振动量。通过数值模拟与试验验证证实了运用类神经网络的主动控制抑制系统自然频率振动进行研究是可行的。     

基于参数优化的连铸结晶器振动位移系统 复合控制研究

本文以伺服电机驱动的连铸结晶器振动位移控制系统为研究对象,针对系统工艺控制中要求伺服电机转速单方向、变 角速度转动,同时考虑系统控制器参数的选取大多依靠经验等问题,提出了一种基于前馈控制与参数优化的 PID 反馈控制相结 合的复合跟踪控制策略。 首先,根据伺服电机驱动的连铸结晶器振动位移系统特性,建立了伺服电机输出转速与振动位移之间 的近似数学模型。 其次,针对伺服电机单方向转动工艺约束条件,确定结晶器振动位移系统以转速补偿作为前馈控制器,保证 系统控制器输出大于零. 再次,针对振动位移系统控制器参数大多依靠经验选取的问题,提出采用一种改进的飞蛾火焰优化算 法优化 PID 控制器参数的策略,以实现结晶器振动位移高精度跟踪控制。 最后,通过仿真与实验验证所提方法的有效性,实验 结果表明:优化后的振动位移调整时间缩短了 0. 3 s,振动位移跟踪相对误差减小了 1. 8% 。     

Implementation of robust adaptive control for robotic manipulator using TMS320C30

A new adaptive digital control scheme for the robotic manipulator is proposed in this paper. Digital signal processors are used in implementing real time adaptive control algorithms to provide an enhanced motion for robotic manipulators. In the proposed scheme, adaptation laws are derived from the improved Lyapunov second stability analysis based on the adaptive model reference control theory. The adaptive controller consists of the adaptive feedforward and feedback controller and PI type time-varying control elements. The control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Moreover, this scheme does not require an accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the adaptive controller is illustrated by simulation and experimental results for a SCARA robot.     

管道复合主动噪声控制系统及其实现

为了提高管道噪声主动控制系统的性能,设计出基于TI公司的TMS320C30芯片作为控制器的实时管道复合噪声主动控制系统(简称ANC系统)。针对前馈ANC可实现较宽的降噪频带,但在实际复杂系统中不能完全满足参考传感器信号和噪声声源要紧密相关要求;而反馈ANC系统中,降噪效果不依赖于声场的相关性,但其降噪频带较窄的特点,设计出复合FXLMSANC系统。在某风机、通风管路系统上进行ANC试验的结果表明,应用复合FXLMSANC方法,能获得比单独使用前馈FXLMSANC算法或反馈FXLMSANC算法更好的降噪效果。     

基于IIR结构的自适应滤波振动主动控制方法

当前自适应滤波前馈控制方法中具有代表性的是滤波-X最小均方(filtered-X least mean square,简称FX-LMS)算法,它通常假定干扰源可测且作为前馈控制器的参考输入,但实际振动控制过程中需要考虑控制输出反馈信号对参考信号的影响,因此滤波-X算法面向实际应用具有较大的局限性。针对这一问题,以机敏压电太阳能帆板结构为模拟试验对象,提出一种基于IIR(infinite impulse response,简称IIR)结构的滤波-U最小均方(filtered-U least mean square,简称FULMS)自适应滤波控制方法,着重分析了控制器结构设计、FULMS算法推理过程、试验模型结构设计、试验平台的构建及其试验验证等环节。经过与FXLMS算法对比仿真试验,笔者所设计的控制算法控制效果良好。将其进行试验验证分析,结果表明,所采用的控制器设计方法与控制算法收敛速度快,控制效果好,为自适应振动控制方法向实际工程应用提供了较好的研究基础。     

摇摆工况下电动汽车高速斜齿轮传动振动控制方法

在摇摆工况下,当无级变速转换为传动变速时,导致扭矩方向及大小的偏移、主转速和从转速不一致,从而产生斜齿轮传动振动问题,为此,提出了基于线性反馈的电动汽车高速斜齿轮传动振动控制方法。通过分析斜齿轮传动时内部的电流走向,明确传动装置的速度比与金属带速度比的反比关系。结合动力学和傅里叶变换算法,推导出速度导纳、位移导纳以及加速度导纳间响应关系,利用响应系数识别 3 种导纳情况下,传动原点处的共振与反共振参数,以此为基础,采用线性反馈混沌控制法建立反馈数据增益矩阵,得出具有稳定周期的调节系数,利用调节系数控制传动点的运行轨迹,完成传动振动的高效控制。仿真测试结果表明,该方法提高了汽车内部共振区域频率波动的吻合程度,有效降低了外界噪声及其他干扰因素导致的传动振动影响,控制性能较好。     

天然气内燃发电机组频率前馈补偿模糊PID控制

提出了天然气内燃发电机组频率采用模糊前馈补偿和模糊PID反馈协调控制的方法,并设计了控制器。模糊前馈补偿控制跟踪负荷变化并对负载扰动做出快速反应,反馈控制中大偏差采用模糊决策,小偏差采用PID控制。试验结果表明,前馈补偿模糊PID频率控制有较好的动态和静态性能,具有有效性和可行性。     

电气传动设备低频 前馈复合控制技术

为减小电气传动设备高频信号扰动的影响,降低设备控制负担,优化高频扰动控制效果,研究综合能源接入下电气传动设备低频 前馈复合控制技术。利用传感器采集扰动信号,建立电气传动设备有限分析元模型,得出电气传动设备作业振幅及扰动信号幅频间关系,预测电气传动设备外部声场,校正误差信号,以基础函数估计扰动信号频域,通过隔声腔物理阻隔扰动信号传播、利用优化后前馈控制系统抑制高频扰动,实现电气传动设备低频 前馈复合控制。算例分析结果表明,所提技术不受电气传动设备作业角度限制,各角度下的吸声系数皆较高,低频 前馈复合控制效果很好,适用性强。