共查询到20条相似文献,搜索用时 0 毫秒
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Wai Ee Wong Lu Feng Zhimin He Jun Liu Cheng Mun Kan Guoxiao Guo 《IEEE transactions on magnetics》2005,41(11):4315-4322
We describe a high-performance servo control system for enhancement of spinstand servo performance. This PC-based system uses a multifunction I/O card for controller output and a high-speed digitizer card capable of sampling the frequency-encoded servo pattern at 500 MS/s. The PC, running under the Linux operating system, uses the Goertzel algorithm decoding scheme to calculate the position error signal (PES) at a 15-kHz update rate for feedback control. The control signal drives a custom-made lead zirconate titanate (PZT) actuator, which moves the suspension and thus the read/write head. A proportional and integral (PI) type servo controller supports a 1.1-kHz servo bandwidth, producing a 21.9% improvement of the positioning accuracy of the spinstand. 相似文献
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A novel circuit used to process analog position error information in a disk drive head-positioning servo system drastically reduces noise in the signal and compensates for effects due to insufficient position sample rate at high carriage velocities. The processed signal does not suffer from envelope droop at high carriage velocities, and lends itself well to track counting algorithms. Because the filter's bandwidth and low-frequency gain are controlled by carriage velocity information, the filter characteristics adapt to environmental conditions for near optimal reduction of noise. 相似文献
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Jia P Kofman J English C 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(10):3150-3158
We present an intensity-ratio error-compensation method to decrease the measurement error caused by projector gamma nonlinearity and image defocus in triangular-pattern phase-shifting profilometry. The intensity-ratio measurement error is first determined by simulating the measurement with the triangular-pattern phase-shifting method with ideal and real captured triangular-pattern images based on the ideal and real gamma nonlinearity functions. A lookup table that stores the intensity-ratio measurement error corresponding to the measured intensity ratio is constructed and used for intensity-ratio error compensation. Experiments demonstrated that the intensity-ratio error compensation method significantly reduced the measurement error in the triangular-pattern phase-shifting method by 28.5%. 相似文献
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电动负载模拟器的非线性因素分析及补偿 总被引:1,自引:0,他引:1
《中国测试》2016,(1):96-101
为提高电动负载模拟器系统的动态性能和信号跟踪准确度,提出针对系统摩擦非线性和间隙非线性进行补偿的方法。分析系统存在的非线性因素及其对系统造成的影响,在此基础上建立其非线性数学模型。采用基于小波神经网络的PID控制器实现摩擦非线性补偿,同时利用间隙逆模型针对间隙非线性进行补偿。利用Matlab软件对补偿结果进行仿真验证,仿真结果显示经过补偿后系统正弦响应曲线跟随性能变好,跟踪误差明显减小,准确度得到很大改善。仿真结果证明:基于小波神经网络的PID控制器和间隙逆模型分别对摩擦非线性和间隙非线性有明显的抑制效果,系统动态性能得到提高。 相似文献
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在周期振动的自适应控制中,压电作动器的非线性特性会产生高次谐波,激发高阶模态振动。为抑制压电作动器的高次谐波激励,同时结合自适应振动控制的特点,提出一种新的作动器非线性补偿方法。该方法将作动器的非线性与结构的动态特性部分融合,用正交多项式从输入输出信号中拟合静态非线性及其逆变换,计算过程简单,数值稳定性高。在控制通道中,通过逆变换对控制信号进行预处理,使得补偿后的输入输出具有线性系统的特征,而输入输出之间的相位差完全由自适应算法进行补偿。实验结果表明,所给出的补偿方法能够抑制高次谐波,并改善了振动控制效果。 相似文献
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The wavefront error caused by centroid position random error is derived in detail, and an exact formula, which evaluates the wavefront error associated with the centroid position random error, is obtained when the Zernike modes are used as the basis for wavefront reconstruction. The formula is proved by two Shack–Hartmann wavefront sensors with different wavefront reconstruction matrices, and it can precisely describe the wavefront measuring error caused by centroid position random error. 相似文献
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A transducer was designed to sense small angular displacements of servo-controlled galvo mirrors in rotary optical storage devices. The transducer is differential in nature, and operates on the principle of linear electrical capacitance variation with area overlap of uniquely shaped capacitor plates. These capacitive plates lie in planes normal to the axis of rotation, and consist of many electrically connected wedge-shaped projections aligned radially to the center of rotation. A prototype was fabricated and tested. For optical storage devices, experimentally determined characteristic curves show sufficient linearity and repeatability for relative position error (RPE) feedback applications, at plate spacings of 0.15 mm or less. A design change, for further extending the linear range of the characteristic curve of the transducer beyond RPE feedback requirements, is described. A circuit design to produce voltage variations proportional to differential capacitance changes in the transducer is discussed, and peak-to-peak signal-to-noise ratio is conservatively approximated at 2×104 with 10 kHz bandwidth 相似文献
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This paper analyzes the phase error for a three-dimensional (3D) shape measurement system that utilizes our recently proposed projector defocusing technique. This technique generates seemingly sinusoidal structured patterns by defocusing binary structured patterns and then uses these patterns to perform 3D shape measurement by fringe analysis. However, significant errors may still exist if an object is within a certain depth range, where the defocused fringe patterns retain binary structure. In this research, we experimentally studied a large depth range of defocused fringe patterns, from near-binary to near-sinusoidal, and analyzed the associated phase errors. We established a mathematical phase error function in terms of the wrapped phase and the depth z. Finally, we calibrated and used the mathematical function to compensate for the phase error at arbitrary depth ranges within the calibration volume. Experimental results will be presented to demonstrate the success of this proposed technique. 相似文献
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《纳米技术与精密工程》2018,(3)
Desktop 3D printers have revolutionized how designers and makers prototype and manufacture certain products.Highly popular fuse deposition modeling(FDM)desktop printers have enabled a shift to low-cost consumer goods markets,through reduced capital equipment investment and consumable material costs.However,with this drive to reduce costs,the computer numerical control(CNC)systems implemented in FDM printers are often compromised by poor accuracy and contouring errors.This condition is most critical as users begin to use 3D-printed components in load-bearing applications or to perform mechanical functions.Improved methods of low-cost 3D printer calibration are needed before their open-design potential can be realized in applications,including 3D-printed orthotics and prosthetics.This paper applies methodologies associated with high-precision CNC machining systems,namely,kinematic error modeling and compensation coupled with standardized test methods from ISO230-4,such as the ballbar for kinematic and dynamic error measurements,to examine the influence and feasibility for use on low-cost CNC/3D printing platforms.Recently,the U.S.Food and Drug Administration's"Technical considerations for additive manufactured medical devices"highlighted the need to develop standards specific to additive manufacturing in regulated manufacturing environments.This paper shows the benefits of the methods described within ISO230-4 for error assessment,alongside applying kinematic error modeling and compensation to the popular kinematic configuration of an Ultimaker 3D printer.A Renishaw ballbar QC10 is used to quantify the Ultimaker's errors and thereby populate the error model.This method quantifies machine errors and populates these in a mathematical model of the CNC system.Then,a post-processor can be used to compensate the printing code.Subsequently,the ballbar is used to demonstrate the dramatic impact of the error compensation model on the accuracy and contouring of the Ultimaker printer with 58%reduction in overall circularity error and 90%reduction in squareness error. 相似文献
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Translated from Izmeritel'naya Tekhnika, No. 9, pp. 45–47, September, 1989. 相似文献
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A new precision circuit has been developed for a phase-type transformer displacement converter in which the errors of the
phase shifter are balanced out; the working principle is described.
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Translated from Izmeritel’naya Tekhnika, No. 10, pp. 26–27, October, 2007. 相似文献
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The operating principle of a new analog-to-digital angular displacement converter circuit that makes it possible to reduce
the error of the phase shifter is considered.
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Translated from Izmeritel’naya Tekhnika, No. 8, pp. 31–33, August, 2007. 相似文献
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V. J. Burkley J. C. Bruch 《International journal for numerical methods in engineering》1991,31(7):1333-1356
Numerical experiments in adapting variations of a computationally simple error estimator (the Zienkiewicz-Zhu estimator) to an existing finite element code are shown. The error estimator used allows both overall and local errors to be estimated. From the local estimates of error, refinements of the mesh are calculated to reach a prescribed error tolerance. These calculated refinements are used by a mesh refiner to produce a modified mesh which lowers the overall error to the prescribed value while keeping the mesh as crude as possible. The physical example on which these numerical experiments are performed is that of free surface flow through an earth dam with a toe drain. It is also shown how the problem formulation affects the error analysis and how the choice of computational scheme affects the mesh adaptation. 相似文献
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可见光通信(VLC)是一项有前景的技术,作为现有无线通信网络的有益补充,可提供高速率、低延迟及多设备接入等通信服务。借助传统无线通信的高性能编码调制技术,已经设计并实现了各种适配于VLC系统的物理层通信技术。不同于传统射频通信,VLC采用LED作为信号的发射源,LED的调制容易产生非线性失真且调制带宽有限,已成为VLC高速通信的技术瓶颈。针对这两方面的挑战,本文以白光LED为出发点,阐述了白光LED能有效兼顾照明和通信的特性,总结和分类了非线性失真补偿和拓展调制带宽的多种技术,最后本文提出了LED封装材料及工艺、新型Micro-LED器件研究、光源布局设计、码间干扰消除技术等开放性研究问题,以期提高可见光通信系统的性能。 相似文献