加速度前馈在高精度伺服跟踪系统中的应用研究

简要介绍了含有前馈校正的复合控制系统,给出了三闭环控制系统的2种双前馈控制方案,详细推导了这2种方案前馈系数的确定过程,经比较得出了速度、加速度双前馈控制方案优于速度、电流双前馈控制方案.最后,对系统加入加速度前馈前后进行了实验比较,结果表明,加速度前馈的加入,有效提高了系统跟踪机动目标的能力.     

前馈补偿技术

介绍了舰载雷达船摇前馈补偿技术，推导出补偿船摇，目标运动产生的跟踪误差的前馈方程式。根据船摇参数和目标运动参数，采用前馈技术可获得较好的隔离度。实验表明，隔离度可达到１７ｄＢ。     

雷测数据动态滞后误差修正新思路

针对动态目标过捷近点时引起的雷测数据动态滞后误差,分析了雷达伺服系统产生动态滞后误差的原因,采用前馈网络的功能,提出前馈滤波系统,从理论上讨论和仿真试验验证了该系统的有效性,为提高数据处理精度提供可靠的数据源。     

基于前馈控制的舰载光电跟踪技术

目标快速运动及舰载平台姿态变化使得舰载光电跟踪系统形成较大的跟踪误差.为了减小该误差,提出了一种基于前馈控制的补偿方案.该方案利用坐标变换给出了由船摇和目标运动引起的跟踪扰动量,并通过滤波求取该扰动量的一阶导数,以此作为跟踪系统的前馈量加入系统中,达到对扰动进行补偿的效果.仿真结果显示,系统的跟踪精度提高了一个数量级.     

一种平流层飞艇高度控制方法

现代平流层飞艇要求飞艇能够安全、平稳地抵达平流层目标高度。首先分析了平流层飞艇高度控制与压差控制的关系, 然后针对平流层飞艇的特点提出了一种前馈式高度控制的方法。仿真结果表明,前馈式高度控制器具有一定的局限性, 不能同时满足高度和压差的控制目标。为此,提出了压差控制器以及两种解决高度控制器与压差控制器融合问题的方案, 最后的仿真结果表明, 限制高度控制权限的方案能保证飞艇安全平稳地到达目标高度。     

用计算机前馈提高船载跟踪雷达角跟踪性能的计算机模拟试验

随着宇航计术的发展及飞行体(飞机、导弹)速度的提高,对跟踪雷达性能的要求愈来愈高,而雷达角跟踪系统本身因受天线结构谐振频率的限制,其带宽不能按目标机动性要求而增加,另外带宽的选择也应考虑随机误差的影响,如雷达载体本身又在运动(船载或机载跟踪雷达),则又增加了新的问題。试验的目的试图采用计算机前馈的办法来解决上述矛盾。七十年代初期国外资料虽有这方面的报导,但目前对我们还是新的尝试。角跟踪系统中在速度回路外面增加一个由速率陀螺组成的稳定回路,以減少雷达天线受雷达载体旋转的影响。摇摆前馈输入点是在速度回路,目标前馈输入点是在陀螺回路,故位置回路带宽可做得窄些,以減小噪声影响,前馈信号也可经平滑以減小随机噪声。     

基于传感器融合预测的改进跟踪前馈控制方法研究

针对光电跟踪系统中CCD相机反馈帧率较低，延迟较大导致跟踪高速目标能力差、响应能力差的问题，提出一种基于传感器融合预测的改进跟踪前馈控制方法。为减小融合获得目标高阶运动状态噪声大的问题，提出一种基于微分跟踪的传感器融合策略；针对图像反馈延迟问题，提出一种降阶匀加速Kalman模型，根据融合获得的运动学信息，结合Kalman滤波进行预测跟踪，补偿脱靶量的时间延迟，得到近似真实的目标位置和速度、加速度信息；针对低频输入信号引入闭环扰动问题，提出一种快速数据扩展方法，实现低频信号到高频信号的扩展；根据传感器融合预测结果，设计跟踪前馈控制器，提高系统的响应速度。仿真结果和实验结果均表明该前馈方法能够对CCD反馈延迟导致的跟踪误差进行补偿。实验结果表明：该方法能够大幅提高系统对高速目标的跟踪性能，在目标运动状态相同条件下，相比补偿前跟踪误差减小约83.67%。     

一种前馈神经网络的快速学习算法

本文提出一种前馈神经网络的快速学习算法。与传统的BP方法相比,本算法有两个改进之处,一是同时将网络的非线性输出误差与线性输出误差作为待优化的目标函数,二是改进了学习过程中误差的反向传播因子。仿真结果表明,使用本文的算法训练前馈神经网络,计算复杂度略高于BP算法,但学习速度却有显著的提高。     

复合多输出前馈函数的密码学特性

该文讨论复合多输出前馈函数和退化的多输出前馈函数,给出了复合多输出前馈函数和退化的多输出前馈函数的一些密码学性质。     

存储采样前馈序列的构造及性质

本文构造了一种新的前馈序列,称为存储采样前馈序列。我们证明了三个结论:存储采样前馈序列具有良好的0—1均衡性;存储采样前馈序列没有好的线性逼近;存储采样前馈序列有比较理想的线性复杂度。     

神经网络在标准热电偶测温中的应用

热电偶在工业测温中有着广泛应用，但其温度和热电势之间呈非线性关系，实际应用中需要采用标准化热电偶并存储和查找分度表来得到实测温度，这样既限制了测温精度，又使其在热电特性发生变化后很难再用。本文利用人工神经网络自学习、自适应的特点以及多层前向神经网络的函数逼近能力来解决热电偶温度计算的问题，并给出了两层前向神经网络和BP算法计算热电偶温度的详细过程。结果表明，这种计算方法准确性高、实用性强。     

基于加速度计的光电跟踪系统等效复合控制

复合控制是提高光电跟踪系统跟踪精度的一种有效方法,它较好地解决了精度和稳定性之间的矛盾;而等效复合控制是复合控制的另一种实现。为了实现等效复合控制,采用加速度计直接测得加速度信息再通过积分得到的速度作为前馈控制信号。实验对比结果表明,加速度计可以作为等效复合控制的传感器,在实际应用中实现伺服跟踪系统精度的提高,加入等效复合控制的光电跟踪伺服系统的跟踪精度提高至原来的6.67倍。     

Evolutionary algorithm based feedforward control for contouring of a biaxial piezo-actuated stage

The main objective of this paper is to establish a precision contouring control of a biaxial piezoelectric-actuated stage. The positioning accuracy of the piezoelectric-actuated stage is limited due to the hysteretic nonlinearity of the piezoelectric actuators (PEA). To compensate this hysteresis problem, a feedforward controller based on an evolution algorithm is proposed. The dynamics of the hysteresis is formulated by the Bouc–Wen model and the evolutionary algorithms (EAs) are studied to identify the optimal parameters of the Bouc–Wen model. To verify the consistency, two micro-contouring tasks are implemented by the proposed feedforward controller with the feedback of linear optical scales in DSP based real-time control architecture.     

基于复合控制的光电搜索跟踪转台控制系统设计与实现

高精度的控制系统是保证光电搜索跟踪系统实现目标稳定跟踪的关键因素之一.为提高光电搜索跟踪转台的响应速度及控制精度,在介绍系统总体功能的基础上,对控制系统进行建模,并设计了基于位置前馈与专家PID算法的复合控制策略,实际应用表明,该系统能对目标实现高精度的稳定跟踪,鲁棒性好,达到了预期的设计要求.     

Ein neues Vorfilter zur Verbesserung des Folgeverhaltens von Bewegungsregelungen

The tracking error of motion control systems which should guarantee high precision — for example considering machine tools — can be considerably reduced by the use of a feedforward filter. The feedforward filter G_v(z^?1) should carry out the compensation of the poles and zeros of the transfer function G_cl(z^?1) of the motion control system. As far as motion control is concerned this compensation is not feasible, since the transfer function G_cl(z^?1) of this kind of control systems has usually unstable or limit-stable zeros. Different methods of feedforward filter designs are known, which also achieve in the case of noncompensable zeros a remarkable performance improvement. Most commonly used is the so called zero phase error tracking (ZPET)-feedforward filter. ZPET-prefiltering leads to phase zero of the frequency response of the overall transfer function G_v(z^?1) G_cl(z^?1) within the whole frequency range. This article introduces a new feedforward concept, which is easy to design and is a result of time domain considerations. The reported investigations show that this feedforward concept leads not only in theory but also under realistic circumstances to a quite reduced tracking error compared to the ZPET-feedforward filter.     

Control of low velocity friction and gear backlash in a machine tool feed drive system

Precision-controlled mechanisms are commonly used in machining applications where the feed rates are low, direction reversals are necessary to obtain the desired work piece profile and precision requirements are in the order of micrometers or sub-micrometers. Under these conditions, friction and gear backlash effects contribute significantly to the dynamics of the system. This study investigated the use of neural network models to compensate for these effects. The approach was to switch between two controllers: (i) a proportional-plus-derivative controller together with a feedforward friction compensator when the transmission gears were engaged; and (ii) a feedforward backlash controller when the transmission gears were disengaged. The control scheme was experimentally verified using a retrofitted geared head engine lathe. The results obtained were compared to those obtained with a compensation method found in the literature.     

一种非判决辅助前向结构载波频差估计方法

本文从最大似然准则出发,提出一种适于旋转对称星座的非判决辅助前向结构载频偏差估计算法.为了解决相位区间跳变问题,从而扩大估计范围,提出了一种新的相位展开方法.对于2π/M旋转对称星座,该估计算法的估计范围可扩大到±1/2MT.计算机仿真给出了该算法在估计范围、估计精度以及计算复杂度方面的性能.     

Particle swarm optimization based feedforward controller for a XY PZT positioning stage

Compensations for cross-axis coupling effect and hysteretic nonlinearity of a novel XY piezo-actuated positioning stage are presented in this study. The piezo-actuated stage utilizes a monolithic flexure-based mechanism (FBM) to achieve translations in X- and Y-axes instead of using stacked mechanisms. A hysteresis model with crossover term is proposed to alleviate the cross coupling effect between X- and Y-stages during precision positioning tasks. System identifications using real-coded genetic algorithm (RGA) and clonal selection algorithm (CSA) are compared with particle swarm optimization (PSO). The results show that PSO provides better performance than the others. Therefore, a feedforward controller with cross-axis coupling compensation is studied and the used for the piezo-actuated FBM to enhance the precision of the coarse positioning stage. The experimental results confirm that the proposed controller can achieve precision tracking tasks with submicron precision.     

Gimbal Angular Velocity Feedforward Method for Magnetically Suspended Control Moment Gyro with Hybrid Magnetic Bearing#

Control moment gyro(CMG) has the advantages of high precision and large output moment. It is the key actuator of agile spacecraft attitude control system. Magnetically suspended CMG(MSCMG) supports high-speed rotor through magnetic bearing, which has the advantages of no friction, no wear, high precision and long life. Hybrid magnetic bearing(HMB) generates bias magnetic field by replacing bias current with permanent magnet, which greatly reduces the power consumption. However, when MSCMG output moment, moving-gimbal effect makes the control current of HMB increase sharply, which result in the rapid increase of power consumption. To solve this problem, gimbal angular velocity feedforward(GAVF) method is proposed in this paper. Firstly, the model of HMB-rotor system containing moving-gimbal effect is established. Secondly, GAVF method is introduced to make the rotor deflect by designing a feedforward matrix with gimbal angular velocity and stiffness of HMB which is determined with rotor deflection angle and rotation speed. Thus, the gyroscopic moment is mainly offset by the bias magnetic field of HMB. Finally, an adaptive compensation method based on GAVF is proposed to maintain the system performance under parameter perturbation. By the above, the power consumption of control current during moment output process is reduced. Simulation and experiment results show the effectiveness of the proposed method.     

一种适用于恒定导通时间控制的高性能定时器电路

本文提出一种适用于恒定导通时间控制的开启时间定时器电路。电路中采用与输入电源电压成正比的电流对电容充电,从而实现定时器的定时时间与输入电源电压成反比,解决了传统恒定导通时间控制中系统工作频率随输入电源电压变化的问题。为了获得高的定时精度,开启时间定时器中的比较器采用了自适应偏置技术,根据输入电源电压的情况动态地设置定时器中比较器的偏置电流。基于0.6μmCD工艺,对所设计开启时间定时器电路进行仿真验证。结果表明,本文所设计的开启时间定时器电路,能够始终保证高的定时精度。同时由于定时时间与输入电源电压成反比,在系统中引入了前馈,极大地提高了系统的线性响应速度。