CN107246901B - Coal bunker material level detection system and method based on string vibration - Google Patents
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Abstract
本发明涉及物料高度检测,具体为一种基于弦振动的煤仓料位检测系统及方法。解决了目前煤仓内部料位高度的检测存在测量速度慢以及测量结果不准确的技术问题。一种基于弦振动的煤仓料位检测系统,包括垂直连接在用于盛放物料的筒仓内部顶端和底端之间的弦线、用于击弦的机械击弦装置、用于采集弦线振动频率的声波频谱仪以及计算机系统;所述计算机系统的信号输出端与机械击弦装置的信号输入端相连接;声波频谱仪的信号输入端与计算机系统的信号输入端相连接。本发明所述检测系统克服了当前常用测量方法测量精度和测量速度不能兼顾、易受粉尘和悬挂物干扰的问题,实现煤仓料位高度的连续、精确检测,并且不受筒仓内粉尘和悬挂物影响。
The invention relates to material height detection, in particular to a coal bunker material level detection system and method based on string vibration. It solves the technical problems of slow measurement speed and inaccurate measurement results in the current detection of the material level height inside the coal bunker. A coal bunker material level detection system based on string vibration, including a string vertically connected between the top and bottom of the silo used to hold materials, a mechanical string striker for striking the string, and a string for collecting the string The sound wave spectrum analyzer of the linear vibration frequency and the computer system; the signal output end of the computer system is connected with the signal input end of the mechanical hammering device; the signal input end of the sound wave spectrum analyzer is connected with the signal input end of the computer system. The detection system of the present invention overcomes the problem that the measurement accuracy and measurement speed of the current commonly used measurement methods cannot be balanced, and is easily interfered by dust and hanging objects, and realizes the continuous and accurate detection of the height of the coal bunker material level, and is not affected by the dust and dust in the silo. Suspension effects.
Description
技术领域technical field
本发明涉及物料高度检测,具体为一种基于弦振动的煤仓料位检测系统及方法。The invention relates to material height detection, in particular to a coal bunker material level detection system and method based on string vibration.
背景技术Background technique
对于煤矿、洗煤厂、电厂等,煤仓的料位检测是煤炭存量、煤炭质量检测的重要指标,对料位的自动、连续监测是自动化程度提高的重要体现。因现场工况复杂、粉尘大、易粘易挂等特点,使得料位的精确、连续测量成为物位测量技术中的一大难点。目前煤仓料位的自动测量最常用的方式主要有重锤法、超声波测距法和激光测距法。其中,重锤法根据重锤下降距离折算料位高度,原理简单、可靠,能够避免粉尘、悬挂物的干扰,测量精度高,但其测量速度较慢,完成一次测量需重锤上下往复,不利于连续监测;超声波法测量一个超声波脉冲从发出到返回整个过程所用的时间,但由于煤仓中粉尘严重、受各种悬挂物的作用会产生虚假回波,影响测量结果,同时,超声波发散角大且功率有限,难以实现长距离测量,量程受限;激光法测量激光脉冲从发出到返回的时间,同样也会受煤仓中粉尘、各种悬挂物的作用产生虚假回波,同时,由于激光传播速度极快,所以传播时间小,对时间测量的相对误差偏大,另外对于煤仓,煤炭为黑色,对光波吸收作用很强,反射光强度很低,不利于测量。For coal mines, coal washing plants, power plants, etc., the material level detection of coal bunkers is an important indicator of coal stock and coal quality detection, and the automatic and continuous monitoring of material level is an important manifestation of the improvement of automation. Due to the characteristics of complex working conditions, large dust, and easy sticking and hanging, the accurate and continuous measurement of material level has become a major difficulty in level measurement technology. At present, the most commonly used methods for automatic measurement of coal bunker material level mainly include weight hammer method, ultrasonic distance measurement method and laser distance measurement method. Among them, the heavy hammer method converts the height of the material level according to the falling distance of the heavy hammer. The principle is simple and reliable, and it can avoid the interference of dust and hanging objects. Conducive to continuous monitoring; the ultrasonic method measures the time taken for an ultrasonic pulse from sending out to returning to the whole process. However, due to the serious dust in the coal bunker and the effect of various suspended objects, false echoes will be generated, which will affect the measurement results. At the same time, the ultrasonic divergence angle Large and limited power, it is difficult to achieve long-distance measurement, and the range is limited; the laser method measures the time from sending out to returning of the laser pulse, and it will also be affected by dust in the coal bunker and various hanging objects to generate false echoes. At the same time, due to Laser propagation speed is extremely fast, so the propagation time is small, and the relative error of time measurement is relatively large. In addition, for coal bunkers, coal is black, which has a strong absorption effect on light waves, and the reflected light intensity is very low, which is not conducive to measurement.
发明内容Contents of the invention
本发明为解决目前煤仓内部料位高度的检测存在测量速度慢以及测量结果不准确的技术问题,提供一种基于弦振动的煤仓料位检测系统及方法。In order to solve the technical problems of slow measurement speed and inaccurate measurement results in the current detection of the internal material level height of the coal bunker, the invention provides a coal bunker material level detection system and method based on string vibration.
本发明所述的基于弦振动的煤仓料位检测系统是采用以下技术方案实现的:一种基于弦振动的煤仓料位检测系统,包括垂直连接在用于盛放物料的筒仓内部顶端和底端之间的弦线、用于击弦的机械击弦装置、用于采集弦线振动频率的声波频谱仪以及计算机系统;所述计算机系统的信号输出端与机械击弦装置的信号输入端相连接;声波频谱仪的信号输出端与计算机系统的信号输入端相连接。The coal bunker material level detection system based on string vibration according to the present invention is realized by adopting the following technical scheme: a coal bunker material level detection system based on string vibration, which includes a and the string between the bottom end, the mechanical hammering device for striking the string, the sound wave spectrometer and the computer system for collecting the vibration frequency of the string; the signal output terminal of the computer system and the signal input of the mechanical hammering device The signal output terminal of the acoustic spectrum analyzer is connected with the signal input terminal of the computer system.
本系统基于弦振动理论,测量弦振动发出的声音频率,利用多项式拟合得到弦长和振动频率的定标模型,精确计算弦长,从而确定料位高度。整个测量过程包括击弦、声音频谱测量、数据分析处理。Based on the string vibration theory, the system measures the sound frequency emitted by the string vibration, uses polynomial fitting to obtain the calibration model of the string length and vibration frequency, and accurately calculates the string length to determine the height of the material level. The whole measurement process includes striking strings, sound spectrum measurement, and data analysis and processing.
本发明所述的基于弦振动的煤仓料位检测方法是采用如下技术方案实现的:一种基于弦振动的煤仓料位检测方法,包括以下步骤:The coal bunker material level detection method based on string vibration of the present invention is realized by adopting the following technical scheme: a coal bunker material level detection method based on string vibration, comprising the following steps:
(a)设筒仓高度为H,料位高度为h,弦长即弦线自由振动的长度为l,当仓内料位发生变化时,弦线自由振动的长度l发生变化;则弦长和料位高度关系为h=H-l;(a) Suppose the height of the silo is H , the height of the material level is h , the length of the chord, that is, the length of the free vibration of the string is l , when the material level in the silo changes, the length l of the free vibration of the chord changes; then the length of the chord The relationship with material level height is h = H - l ;
(b)、料位定标(b), material level calibration
筒仓料位变化时,弦线自由振动的长度l也变化,同时料位变化也会使弦线的张力发生微小变化,弦线的振动频率f也会发生相应的变化;对此采用多项式拟合建立弦长l和频率f的数学模型,利用回归分析来得到定标模型;将弦长l和频率f的关系用高阶多项式表示如下:When the material level of the silo changes, the length l of the free vibration of the string also changes. At the same time, the change of the material level will also cause a slight change in the tension of the string, and the vibration frequency f of the string will also change accordingly; A mathematical model of chord length l and frequency f is established, and regression analysis is used to obtain a calibration model; the relationship between chord length l and frequency f is expressed by a high-order polynomial as follows:
l=a 0+a 1 f + a 2 f 2+…+ a n f n l = a 0 + a 1 f + a 2 f 2 +…+ a n f n
式中a 0、a 1、…,a n 分别为各阶回归系数,具体阶数n由用来定标的数据量来决定;在不同料位高度下,通过计算机系统控制电机带动联动杠杆击弦,并通过声波频谱仪采集弦线振动频率,进而测出料位高度分别为l 1、l 2、…、l m 时对应的弦线的振动频率f 1、f 2、…、f m ,其中,m>n,可得到回归方程:In the formula, a 0 , a 1 ,..., a n are the regression coefficients of each order, and the specific order n is determined by the amount of data used for calibration; at different material level heights, the computer system controls the motor to drive the linkage lever to hit string, and the vibration frequency of the string is collected by the acoustic spectrum analyzer, and then the vibration frequency f 1 , f 2 , ..., f m of the corresponding string is measured when the material level height is l 1 , l 2 , ..., l m , Among them, m > n , the regression equation can be obtained:
数学模型建立以后,计算机系统在相应软件的支持下结合相关数据进行拟合,得到回归方程系数a 0、a 1、…,a n 的值,建立弦长l和频率f之间的定量关系;After the mathematical model is established, the computer system, with the support of the corresponding software, combines the relevant data for fitting, and obtains the values of the regression equation coefficients a 0 , a 1 ,..., a n , and establishes the quantitative relationship between the chord length l and the frequency f ;
(c)通过计算机系统控制电机带动联动杠杆击弦,并通过声波频谱仪测得弦线的振动频率后,由l=a 0+a 1 f + a 2 f 2+…+ a n f n 式计算出自由振动弦长l,带入h=H-l式即可得到筒仓内实际的料位高度。(c) The computer system controls the motor to drive the linkage lever to strike the string, and after measuring the vibration frequency of the string through the acoustic spectrum analyzer, the formula l = a 0 + a 1 f + a 2 f 2 +…+ a n f n Calculate the chord length l of free vibration and put it into h = H - l formula to get the actual material level height in the silo.
对于一种特定的物料,测量前需要进行定标,即在筒仓内装填不同高度的物料,然后分别测量每个高度下的弦线在相同频率的外力作用下的振动频率,列出相应的多项式,然后根据上述多个多项式拟合出各阶回归系数,完成定标;之后就可以进行实际的测量了。For a specific material, calibration is required before measurement, that is, materials of different heights are filled in the silo, and then the vibration frequency of the string at each height under the same frequency of external force is measured, and the corresponding polynomial, and then fit the regression coefficients of each order according to the above-mentioned multiple polynomials, and complete the calibration; after that, the actual measurement can be carried out.
本发明所述检测系统克服了当前常用测量方法测量精度和测量速度不能兼顾、易受粉尘和悬挂物干扰的问题,实现煤仓料位高度的连续、精确检测,并且不受仓筒内粉尘和悬挂物影响。所述方法测量准确,处理速度快,能够满足目前煤矿、电厂、洗煤厂的需要;不仅可用于煤炭的测量,还可以用于其它矿石以及化工原料的料位测量。整个系统结构简单,成本低廉。The detection system of the present invention overcomes the problem that the measurement accuracy and measurement speed of the current commonly used measurement methods cannot be balanced, and is easily interfered by dust and hanging objects, and realizes the continuous and accurate detection of the height of the coal bunker material level, and is not affected by the dust and dust in the bin. Suspension effects. The method has accurate measurement and fast processing speed, and can meet the needs of current coal mines, power plants, and coal washing plants; it can be used not only for coal measurement, but also for material level measurement of other ores and chemical raw materials. The whole system has simple structure and low cost.
附图说明Description of drawings
图1 本发明所述煤仓料位检测系统的结构示意图。Fig. 1 is a schematic structural diagram of the coal bunker material level detection system of the present invention.
1-筒仓,2-弦线,3-声波频谱仪,4-计算机系统,5-电机,6-联动杠杆。1-silo, 2-string, 3-acoustic spectrum analyzer, 4-computer system, 5-motor, 6-linkage lever.
具体实施方式Detailed ways
所述机械击弦装置包括电机5和联动杠杆6;所述电机5的信号输入端与计算机系统4的信号输出端相连接,电机5的动力输出端连接有用于击发弦线2的联动杠杆6。The mechanical striking device includes a
声波频谱仪3、电机5和联动杠杆6均位于弦线2靠近筒仓1顶端的位置处。弦线2采用钢丝绳。The
实施例Example
1、装置结构1. Device structure
所述系统结构如图1所示。该系统包括:弦线2,机械击弦装置,声波频谱仪3,计算机系统4。所述弦线2为一垂直安装的、直径约为3~5cm、长度与筒仓1高度相当的钢丝绳,其上下两端分别与筒仓1的顶端和底端固定;机械击弦装置由电机5和联动杠杆6组成,其转速和扭矩由计算机系统4控制,即可以在一定范围调节击弦频率和击弦力度;计算机系统4接收声波频谱仪3的测量数据,进行处理分析,得到料位高度,同时,计算机系统4还进行击弦、声音频谱测量、数据分析处理过程的时序控制。The system structure is shown in FIG. 1 . The system includes: a
2、测量原理2. Measuring principle
根据弦振动理论,两端固定的连续均匀弦线振动时,其运动可以表示为多个驻波的叠加。对于第n个驻波,弦线各点做谐振动的振幅和频率分别为:According to the theory of string vibration, when a continuous uniform string with fixed ends vibrates, its motion can be expressed as the superposition of multiple standing waves. For the nth standing wave, the amplitude and frequency of harmonic vibration at each point of the string are:
振幅 (1)amplitude (1)
频率 (2)frequency (2)
式中,l为弦长,T为弦线张力,ρ为弦线密度。其中,n=1时对应的振动频率为基频,n为其它值时为各次谐频。由上式可以看出,弦线的振动包括多种频率,但基频强度比其他谐频强得多, 因此它决定弦的频率,所以本发明通过测量弦振动基频计算弦线长度。根据(2)式,弦振动基频与弦长、弦的张力、弦密度有关,对于确定弦线,其密度为一常数。In the formula, l is the string length, T is the string tension, and ρ is the string density. Wherein, when n =1, the corresponding vibration frequency is the fundamental frequency, and when n is other values, it is each harmonic frequency. It can be seen from the above formula that the vibration of the string includes multiple frequencies, but the strength of the fundamental frequency is much stronger than other harmonic frequencies, so it determines the frequency of the string, so the present invention calculates the length of the string by measuring the fundamental frequency of the string vibration. According to formula (2), the fundamental frequency of string vibration is related to string length, string tension and string density. For a certain string, its density is a constant.
当仓内料位发生变化时,弦线2自由振动的长度l发生变化,如图1所示,设筒仓高度为H,料位高度为h,则弦长和料位高度关系为:When the material level in the silo changes, the length l of the free vibration of the
h=H-l (3) h = H − l (3)
3、料位定标3. Material level calibration
筒仓1料位变化时,弦线自由振动的长度l也变化,同时料位变化也会使钢丝弦线的张力发生微小变化,如果测得振动频率直接按照(2)式计算弦长,会带来计算误差。而张力对料位高度的变化规律不容易由数学公式定量描述,基于此,本发明用多项式拟合建立弦长l和频率f的数学模型,利用回归分析来得到定标模型。将弦长l和频率f的关系用高阶多项式表示如下:When the material level of
l=a 0+a 1 f + a 2 f 2+…+ a n f n (4) l = a 0 + a 1 f + a 2 f 2 +…+ a n f n (4)
式中a 0、a 1、…,a n 分别为各阶回归系数,具体阶数n由用来定标的数据量来决定。通过使用重锤法测出料位高度分别为l 1、l 2、…、l m 时对应的振动频率f 1、f 2、…、f m (其中,m>n),可得到多组结构形式(回归方程):In the formula, a 0 , a 1 ,..., a n are the regression coefficients of each order respectively, and the specific order n is determined by the amount of data used for calibration. By using the hammer method to measure the corresponding vibration frequencies f 1 , f 2 , ..., f m when the material level height is l 1 , l 2 , ..., l m (among them, m > n ), multiple groups of structures can be obtained Form (regression equation):
数学模型建立以后,用MATLAB、SPSS等软件可以对相关参数进行拟合,得到回归方程系数a 0、a 1、…,a n 的值,建立弦长l和频率f之间的定量关系。After the mathematical model is established, the relevant parameters can be fitted by software such as MATLAB, SPSS, etc., and the values of the coefficients a 0 , a 1 ,..., a n of the regression equation can be obtained, and the quantitative relationship between the chord length l and the frequency f can be established.
测得弦线振动频率后,由式(4)计算自由振动弦长l,带入(3)式即可得到料位高度。After measuring the vibration frequency of the string, calculate the length l of the free vibration string from formula (4), and bring it into formula (3) to get the material level height.
通过计算机控制电机的转速,以5~20Hz的频率连续击弦,即可实现对料位高度的连续测量。The speed of the motor is controlled by the computer, and the string is continuously struck at a frequency of 5-20 Hz to realize continuous measurement of the material level.
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