凹口滤波器技术在天气雷达伺服系统中的应用

讨论了天线座结构谐振频率对伺服稳定裕度的制约问题。提出了采用电子电路(凹口滤波器)有效抑制天线座谐振频率的峰值,从而等效提高天线座结构谐振频率的阻尼系数的解决方案。详细分析了凹口滤波器电路的特性,并成功地将凹口滤波器技术应用到大型天线伺服系统中。     

电压对含有齿隙伺服系统的影响

为了研究电机输入电压和传动问隙对伺服系统带宽的影响,建立了含有齿隙伺服系统的模型,得出了伺服系统反谐振频率和谐振频率的计算公式。通过对不同电压和齿侧间隙下伺服系统的仿真,定量地给出了齿侧间隙大小和电压与该机构响应频率的对应关系。对于一个带有减速器的伺服系统,这样就能够确定满足带宽下的最大输入电压和最大传动间隙。     

光电设备伺服系统机械谐振检测和抑制

在现代国防军工领域,光电系统被广泛应用于火控、侦察、制导等武器系统中。随着目标机动性能的提升,光电武器系统对其伺服系统动态性能的需求也不断提高,光电伺服系统的带宽也要随之拓展。但机械系统固有特征不会改变,接近或者超过自然机械共振频率的驱动能量就会引起机械谐振。为了提高光电伺服系统性能,需对检测和抑制机械谐振的问题进行研究。首先通过激励信号性质分析,选取性质优良、计算简单的激励信号对光电伺服系统的机械谐振进行参数辨识,然后设计可参数化的陷波滤波器进行在线参数调整,就可实现快速有效地机械谐振抑制。实验结果表明,该机械谐振检测和抑制的方案能够精确地检测机械谐振频率,很好地抑制机械谐振产生的影响,提高光电伺服系统的动态性能。     

某经纬仪方位谐振频率分析

谐振频率是光电经纬仪的一个重要指标,直接影响着经纬仪的动态特性和跟踪精度。工程上对光电经纬仪进行谐振频率估算时,一般采用霍尔兹法。但实际上由于光电经纬仪结构十分复杂,很难精确地计算其等效惯量与刚度,即使算出来其结果的误差也很大。本文针对某经纬仪的垂直轴系进行结构简化,建立了方位谐振频率分析的弹簧力学模型,通过有限元分析计算了在等效支承条件下的前几阶固有频率和振型图。计算结果与伺服系统正弦激振测试结果基本一致。     

火控系统模拟转台传动链刚度设计与试验

748B转台是三维火控系统模拟中的重要设备。为达到满意的跟踪性能要求,我们认真地进行了传动链刚度设计与试验。 本文从转台设计实践、零部件试验等方面来介绍传动链刚度的设计计算方法、测试方法及测试结果,并对如何提高传动链刚度以改善系统性能加以研究与探讨。 传动链刚度与系统性能密切相关。传动链刚度越大,表明结构组合的谐振频率越高,有利于系统频带的提高。因伺服系统在谐振频率附近是无法工作的。一般要求谐振频率大于伺服系统带宽的3～5倍。因此提高传动链谐振频率是结构设计者的主要任务之一。 传动链刚度包括传动轴刚度、齿轮刚度、减速器各支承刚度及箱体刚度等等。而且转台各框架与传动链紧密连接着,所以框架的刚度直接影响着传动链综合刚度。 一、转台传动链刚度设计与计算 在初步完成转台结构设计之后,需进行刚度计算。若刚度未满足总体要求,则即需更改结构设计。 传动链总刚度用下式计算:     

智能积分器在船载大口径天线伺服系统中的应用

随着天线口径的增大,对于伺服系统的要求也越来越高。大口径天线的刚性和结构谐振频率降低,导致伺服系统的动态滞后加大,甚至可能造成雷达丢失目标。通过对新测量船伺服控制系统的分析,建立了伺服系统的控制模型,并将智能积分器应用到位置控制环路中。仿真结果表明,智能积分器能够有效的减小超调量,加快调节速度,取得了较好的控制效果。     

舰载搜索雷达天线座举臂式结构与斜轴式结构的比较

舰载搜索雷达天线座架设在舰艇桅杆上面，要求其重量轻、强度高、耐冲击、振动，且谐振频率要满足伺服系统带宽的需要。介绍了舰载搜索雷达天线座举臂式结构与斜轴式结构的结构形式及其受力分析，并对二者进行了比较。     

1.8GHz AlN薄膜体声波谐振器的研制

提出了基于AlN压电薄膜多层结构的1.8 GHz射频薄膜体声波谐振器(FBAR),并进行了研究。采用修正后的MBVD等效电路模型对器件的谐振特性进行了分析和模拟。给出了采用半导体加工工艺制备器件的工艺流程,并实际制做谐振器样品,样品的测试结果:器件的串联谐振频率fs和并联谐振频率fp分别为1.781和1.794 GHz,相应的有效机电耦合系数为1.8%;串联谐振频率处和并联谐振频率处的Q值分别为308和246。该谐振器样品实际尺寸为0.45 mm×0.21 mm×0.5 mm,可以用来制备高性能的滤波器、双工器和低相噪射频振荡器等。     

振荡伺服系统的自适应控制设计

本文讨论了一种新的模拟随动和低固有谐振频率的机电伺服系统自适应控制的应用。自适应装置的设计基于描述一稳定域的李亚图函数。并阐明了5阶长轴伺服系统在动态扰动方面所表现的完全满意的结果。     

基于有限元法的半球谐振陀螺谐振子分析

利用有限元分析软件ANSYS,建立了半球谐振陀螺核心部件谐振子有限元模型并进行了模态分析,确定了各阶振动形式和频率,通过与实际测试结果比较,验证了模型的合理性和准确性。分析谐振子结构参数对各阶振型和频率的影响,对其进行了优化设计。优化后的结构工作频率与其他振型频率的差大于1 kHz,有效避免谐振子的工作谐振与其他各阶振动的模态耦合。     

An Adaptive Control Scheme for Oscillatory Servo Systems

The application of a new model-following, adaptive control to an electromechanical servo system with low natural resonance frequency is discussed. The design of the adaptation mechanism is based on the use of a special Liapunov function describing the stability domain. Results are presented which show consistent improvement in the dynamic response for a fifth-order, long-shaft, servo system.     

位置随动系统动态指标自动测量系统设计

介绍一种位置随动系统动态指标的自动测量系统。该系统依据虚拟仪表的概念通过测量位置随动系统的一次阶跃响应，在快速准确地得到被测系统主要时域指标的同时，也可得出系统的闭环带宽等频域指标，既大大简化了测试过程、缩短了测量时间，又保证了测量精度、避免了人为因素的影响。该系统已在某火控雷达随动系统性能测试中得到有效验证。     

Suppression of torsional oscillations in a high-performance speedservo drive

This paper deals with the problem of mechanical resonance in modern servo drive systems having the speed control loop bandwidth and resonance frequency above 100 Hz. To enable the extension of the range of stable gains in the presence of flexible coupling, a simple and straightforward modification of the speed loop controller is proposed in order to augment the performance of present speed controllers and to make them accordant with mechanical structure suffering from the compliance problem. This paper is comprised of the analytical considerations, straightforward design guidelines, and results of experimental verification obtained by an experimental setup with the elastically coupled 7-N m synchronous servo motor and mechanical resonance frequency of 160 Hz     

High-bandwidth high-accuracy rotary microactuators for magnetichard disk drive tracking servos

Reports on the design, fabrication, and testing of an electrostatic microactuator for a magnetic hard disk drive (HDD) tracking servo. The design requirements for a microactuator are investigated. These include high Z-directional stiffness, low in-plane stiffness, high structural aspect ratio, large output force, high area efficiency, low cost, and mass batch production. An area-efficient rotary microactuator design was devised, and microactuators were successfully fabricated using innovative processing technologies. The microactuator has a structural thickness of 40 μm with a minimum gap/structure width of approximately 2 μm. Its frequency response was measured and it was determined that it can be modeled as a second-order linear system, up to the 26-kHz frequency range. Moreover, the microactuator will enable the design of a servo system that exceeds a 5-kHz servo bandwidth, which is adequate to achieve a track density of more than 25 kilotrack per inch (kTPI). The microactuator/slider assembly was also tested on a spinning disk, with its position controlled by a PID controller using the magnetic position error signal written on the disk. An accuracy of about 0.05 μm was observed when the servo controller was turned on. Continuous-time dual-stage servos were designed and simulated using the μ-synthesis technique. A sequentially designed SISO and a MIMO control design method have been shown to be capable of meeting prescribed uncertainty and performance specifications     

Resonant frequency estimation for adaptive notch filters in industrial servo systems

This paper proposes a new algorithm for estimating the resonant frequency of adaptive notch filters used in servo systems. Notch filters and adaptive notch filters are widely used in commercial servo systems for suppressing a resonance which is a major obstacle in improving their performance. However, the conventional frequency estimation algorithm gives a dynamic behavior that is proportional to the difference between the square of the estimated frequency and the square of the actual frequency. This can cause the estimation dynamics to be too slow for low-frequency resonances, if both low- and high-frequency resonances are present and if the estimator gain is designed for a high frequency. This paper develops a new algorithm to give a dynamic behavior that is proportional to the difference in the estimated frequency and actual frequency. This allows selecting the estimation parameters independent from the value of resonant frequencies. The developed algorithm is implemented to a production servo controller and applied to a production printed-circuit-board inspection system. The experimental results show that the developed algorithm is much more effective in suppressing the resonances of both low- and high-frequencies, compared to the pervious algorithm. Furthermore, the ability to suppress vibration allows increasing the feedback gain, which in turn allows improving the tack time performance from 190 ms to 100 ms. All experiments reported in this paper were performed in an actual industrial environment using a production system, and the developed algorithms are applied to the production system.     

Head-positioning control using resonant modes in hard disk drives

The best way to enhance the input/output (I/O) performance of a hard disk drive is by increasing the spindle speed. Therefore, the effect of windage vibrations caused by the airflow increases as the spindle speed increases. The servo bandwidth is limited by the primary resonant frequency of the mechanical system. However, the frequencies of the windage vibrations are higher than the primary resonant frequency. Accordingly, these frequencies are also above the servo bandwidth and are too high to be controlled by a conventional control system. In response to this problem, we have developed two methods for designing a servo control system that can suppress the windage vibrations. One method uses a stable mechanical resonant mode, and the other uses a stable resonant mode created by a digital filter. By using these methods, the head-positioning system can control the vibrations above the frequency of the primary resonant mode and the servo bandwidth. Application of these methods to actual hard disk drives showed that they can greatly decrease the windage vibrations, in which the peak frequency is about six times the open-loop gain 0-dB crossover frequency.     

多谐差相信号在伺服系统频率特性测试中的应用

为了减少伺服系统频率特性测试的测试时间,提高测试精度,选用非均匀功率谱的多谐差相信号作为激励源。该信号具有较低的峰值因子,还可以使激励更加平稳均匀。以某型舵机为例进行实验,结果表明,其测试精度与传统的正弦扫描信号作为激励的情形相比,幅频特性的误差保持在±0.069dB以内,相频特性的误差保持在±0.602°以内,测试时间减少53.3%,在测试过程中系统运行平稳,适合频率特性的快速高精度测试。     

基于伺服电机控制的三维皮托管测速系统设计

为了改进现有皮托管的测速方法,介绍了一种三维皮托管测速系统方案。该方案采用伺服电机作为驱动部件,磁栅编码器作为位置检测器,其控制系统的框架采用LabVIEW+PLC的两极控制结构。实验过程表明,该系统能有效避免烟道中气体紊流等因素带来的干扰,从而准确地测量烟道尾气的流速;可视化的人机界面为测速操作、数据采集、数据处理等带来便利。文中的重点在于测速原理的改进、伺服电机驱动控制系统与人机界面LabVIEW的编程算法的实现。