基于时间序列的时栅数控转台动态建模研究

时栅运用到全闭环数控转台作位置检测传感器时,需采用时空变换算法将时栅的时域信息转换成空域信息。利用时间序列对时栅数控转台的动态特性进行建模,依据一系列过去测量值预测下一采样时刻角位移,将原本等时采样的绝对式角位移转换为全闭合数控系统需求的等空间增量式连续脉冲。介绍了动态模型选择标准、参数估计、模型检验的原理和算法。采用当前预测值对上一次预测误差进行实时修正,以消除累计误差保证测量精度。实验证明了采用动态模型预测算法能保证动态数控角位移测量误差控制在±3″以内,实现了精密动态全闭环角位移测量。     

基于支持向量机时栅数控转台时序预测研究

时栅代替光栅等传统位移传感器运用到全闭环数控转台做角位移检测部件,需采用时空变换算法将时栅的时域信息转换到空域信息。运用时间序列分析出时栅数控转台的测试数据依存特性,采用支持向量机建立起未来测试数据和历史样本的映射关系,从而得到测试数据中隐含的规律。依据过去相关测量值采用支持向量机回归预测下一采样时刻角位移,将原本等时采样的绝对式角位移转换为全闭合数控系统需要的等空间增量式连续脉冲。并且在误差控制方面,采用当前预测值对上一次预测误差进行实时修正,消除累计误差保证测量精度。实验证明支持向量回归的时间序列预测算法能有效保证动态数控角位移测量误差控制在±2.5″以内,实现精密全闭环角位移测量。     

基于AR模型的转台位置预测方法研究

文中以时栅传感器作为CNC系统的位置检测元件,为了解决时栅数控转台在高精度伺服控制过程中的动态位置反馈误差问题,研究了利用AR模型对转台位置进行预测测量的方法。介绍了预测测量的原理、预测方法及其模型系数的求解方法,并搭建了一套实验装置。经实验表明,基于AR模型的转台位置预测测量方法正确可行,通过修正后预测误差为±2″.     

时栅式直驱转台位置反馈智能接口设计

分析时栅式直驱转台位置反馈存在的动态位置反馈误差。提出利用预测测量方法,将时栅绝对式离散角度测量值转化为增量式连续脉冲信号。研制时栅式直驱转台位置反馈与控制智能接口电路,实现空间位置预测测量。开展预测实验,测得直驱转台空间位置的动态预测误差为!4″,表明时栅可以满足直驱转台高精度的要求。     

基于BP神经网络的时栅时序预测测量研究

为了将时栅应用于全闭环数控系统,需完成时栅信号由时域到空域的转换。通过BP神经网络预测模型找出实测数据中的隐含规律进而建立起样本和未来实测数据的映射关系,预测出下一个周期内时栅的测量角度值,实现时栅绝对式角度值与光栅数控系统所需的增量式连续脉冲的转换;为了保证测量精度,利用当前测量值对上一次的预测误差进行校正。实验表明:基于BP神经网络预测算法的时栅系统可以实现时域信号向空域信号的转换,且误差精度为±2″,满足了数控系统对测量精度的要求。     

寄生式时栅传感器动态测量误差的贝叶斯建模

为了提高寄生式时栅传感器的测量精度,分析了它的工作原理和动态误差组成,得到其主要误差分量为常值误差、周期误差和随机误差等。针对寄生式时栅误差特点,建立了寄生式时栅动态误差高精度预测模型,并与其他建模方法进行了比较。选用插入标准值的贝叶斯预测模型,以实际测量的传感器第一个对极动态误差数据进行建模,在后续对极特定位置插入部分实际误差测量数据,建立误差预测模型,预测了传感器后83个对极的动态误差。另选用三次样条插值和BP神经网络建模方法对寄生式时栅整圈动态误差建模,并与建立的误差模型进行了对比。验证实验表明,三次样条插值建模时间最短(0.62s),但其建模精度不高(16.050 0″);贝叶斯动态模型建模时间(0.86s)略长于三次样条插值,但建模精度最高(0.415 3″);BP神经网络建模时间最长(32min),但建模精度最低(19.680 2″)。同时贝叶斯插入标准值建模方法所需数据点(69395个)远少于三次样条和BP神经网络建模数据点(235526个),节省了大量的标定时间和建模数据量,因此可用于寄生式时栅传感器的动态测量误差高精度建模修正。     

基于时栅的直驱转台误差分析与建模

基于时栅的直驱转台是一种新型零传动数控转台,可分析直驱系统的误差源。利用齐次坐标变换的方法分析并给出了转台转动副的几何误差模型,并根据摩擦与速度的稳态关系建立Stribeck摩擦的数学模型。本文进行的误差分析和误差建模可为其它类型的多轴转台的误差建模研究提供参考。     

时栅动态测量误差建模与补偿技术研究

为提高时栅传感器动态测量精度,针对时栅的误差特点,提出对动态测量误差的周期性成分和随机性成分分别建模的思想。采用傅里叶级数逼近的方法对误差中的周期性成分进行建模,利用最小二乘方法对逼近模型参数进行寻优,选取比重较大的谐波参数对误差的周期性成分进行分离,对于分离后残留的随机性成分采用支持向量回归(Support vector regression,SVR)模型进行预测,利用交叉验证的方法对回归预测模型进行参数寻优和细化,选取最优的核函数参数g和惩罚因子C,使得残差均方达到最小。研发误差补偿系统,对时栅动态测量误差进行补偿。试验结果表明,运用该建模方法和模型,时栅传感器动态测量误差的峰峰值由38.2″降至3″,有效地降低了测量误差,大幅度提高了传感器的测量精度。     

空间精密位移信号软细分方法研究

为了解决高精度数控装备对位移传感器高分辨力反馈的需求,本文提出通过对空域信号特征的分析,从时空变换理论模型的角度去研究位移测量问题;利用光栅周期性栅线作为等空间位置触发位置采样建立空间序列模型;通过对光栅莫尔条纹信号自适应预测细分模型阶数与系数估计算法完成光栅莫尔条纹信号细分。实验结果证明此方法可以实现光栅莫尔条纹400倍细分,细分精度优于信号周期的±1%。此细分方法利用光栅刻划精度,信号细分精度与光栅信号波形质量无关,在不增加硬件的条件下实现光栅莫尔条纹精密细分,具有重要实际应用价值。     

基于时空域变换和动态预测的光栅信号细分方法

为了提高光栅信号的细分倍数和细分精度,提出一种基于时空域变换和动态预测的光栅信号细分方法。根据光栅栅距与电信号周期的对应关系,利用该电信号过零点触发时间采样,完成空间基准向时间序列的转化。通过时间序列分析建立动态预测模型,预测下一个采样时间,并在预测时间内发送光栅信号细分脉冲。实验表明,细分倍数为400和800时的角位移细分误差均为±1. 2″,且光栅运动加速度及其变化率越小,细分误差越小。     

Application of a diffraction grating and position sensitive detectors to the measurement of error motion and angular indexing of an indexing table

In this paper, two systems for the measurement of the error motion and angular indexing of a rotary indexing table have been developed. A laser diode, a laser holder and a position sensitive detector (PSD) are integrated as a simple measuring device for the measurement of the rotary error without using a precision reference artifact (a cylinder or a sphere), multiple probes or error separation methods. The laser diode is assembled in the laser holder and fixed on the rotary table. The PSD is set up above the laser holder to detect the position of an incident laser beam from the laser diode. When the rotary table rotates, the rotary error changes the direction of the incident beam and also the position of the spot on the PSD. For the measurement of the angular indexing, a reflective diffraction grating and two PSDs are integrated as a high-resolution angle measuring device without using an autocollimator or a laser interferometer system. The diffraction grating is set at the center of the rotary table and reflects an incident laser beam into several diffractive rays. Two PSDs were set up for detecting the positions of ±1st-order diffraction rays. A simple algebraic method is used to solve the angular indexing through an optical analysis. The experimental results showed the feasibility of the proposed test devices.     

场式时栅位移传感器研究

根据作者前期提出的“时空坐标转换理论”和基于旋转机械的“单齿式时栅”，再提出基于运动场的“行波磁场式时栅”方案，可克服机械式时栅的缺点，使时栅的商品化应用成为可能，并将研究领域扩展到直线测量。     

空域小波分析法及其在故障诊断中的应用

介绍了空域小波分析的基本原理及在旋转机械故障诊断中的应用。认为空域小波变换良好的空—频局部化特性为提取信号在任意部位所包含的频率分量及故障的精确定位提供了有效的分析手段     

High-throughput accurate-wavelength lens-based visible spectrometer

A scanning visible spectrometer has been prototyped to complement fixed-wavelength transmission grating spectrometers for charge exchange recombination spectroscopy. Fast f/1.8 200 mm commercial lenses are used with a large 2160?mm(-1) grating for high throughput. A stepping-motor controlled sine drive positions the grating, which is mounted on a precision rotary table. A high-resolution optical encoder on the grating stage allows the grating angle to be measured with an absolute accuracy of 0.075 arc sec, corresponding to a wavelength error ≤0.005?A?. At this precision, changes in grating groove density due to thermal expansion and variations in the refractive index of air are important. An automated calibration procedure determines all the relevant spectrometer parameters to high accuracy. Changes in bulk grating temperature, atmospheric temperature, and pressure are monitored between the time of calibration and the time of measurement to ensure a persistent wavelength calibration.     

Measurement and processing of vibro-acoustic signal from the process of rock disintegration by rotary drilling

The paper is focused on methods aimed at processing of vibro-acoustic signal from the process of rock disintegration by rotary drilling. The idea is to use the measured accompanying vibro-acoustic signal emerging in the process of drilling as an integrating information resource. The process of rock disintegration by rotary drilling is among those technological processes which mathematical modeling based on the known laws of physics does not lead to satisfactory results. Here can be applied an empirical approaches that lead to a model applicable to some limited space. An important feature of the rock disintegration process is its relatively strong stochastic component of the signal. From the above, it is necessary to rise from the selection of suitable processing of measured signal. Measured accompanying vibro-acoustic signal is integrating information sources, containing some information on the nature and mode of the current rock drilling. This signal is explicitly represented in the time domain by its behavior of amplitudes or in the frequency domain by its spectrum. The information contained in this signal may be in the form of defined characteristics of signals in time or frequency domain.     

用于高精度数显时栅转台的全自动测控系统

设计了一种集数据采集、处理和控制于一体的数显时栅转台全自动测控系统。介绍了系统的硬件组成及软件各个模块的功能,并给出了增量型数字PID算法的主要程序框图。本系统具有较高的智能化,能在无人干预的情况下自动完成仪器的标定和测试工作。使用结果表明,测试效率和效果达到了要求的指标。