CN112304493B - A CCD camera-based detection method for amplitude-frequency characteristics of optical pressure-sensitive coatings - Google Patents

A CCD camera-based detection method for amplitude-frequency characteristics of optical pressure-sensitive coatings Download PDF

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CN112304493B
CN112304493B CN202011186794.7A CN202011186794A CN112304493B CN 112304493 B CN112304493 B CN 112304493B CN 202011186794 A CN202011186794 A CN 202011186794A CN 112304493 B CN112304493 B CN 112304493B
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葛宁
高丽敏
姜衡
杨冠华
蔡明�
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Abstract

The invention provides a CCD camera-based method for detecting the amplitude-frequency characteristic of an optical pressure-sensitive coating, which comprises the following steps: the signal generator is connected with an external trigger interface of the laser light source and controls the working state of the laser light source; meanwhile, the signal generator is connected with an external trigger interface of the CCD camera to control the working state of the CCD camera, and when the frequency of the sinusoidal pressure standing wave is f1While obtaining the amplitude Am(f1) (ii) a Keeping the amplitude of the sinusoidal pressure standing wave stable and unchanged, and controlling the frequency of the sinusoidal pressure standing wave from f1Gradually increasing to obtain the cut-off frequency and the limiting frequency of the PSP coating. According to the method, the time sequence of the CCD camera is controlled, and the low-frame-rate CCD camera collects the fluorescent image sequence of the pressure sensitive coating under the high-frequency pulsating pressure, so that the dynamic pressure distribution of the universe is obtained.

Description

一种基于CCD相机的光学压敏涂料幅频特性检测方法A CCD camera-based detection method for amplitude-frequency characteristics of optical pressure-sensitive coatings

技术领域technical field

本发明属于压敏涂料幅频特性检测技术领域，具体涉及一种基于CCD相机的光学压敏涂料幅频特性检测方法。The invention belongs to the technical field of detection of amplitude-frequency characteristics of pressure-sensitive coatings, in particular to a detection method for amplitude-frequency characteristics of optical pressure-sensitive coatings based on a CCD camera.

背景技术Background technique

压力作为自动化控制的热工三参量(压力、温度、流量)之一，在测量与控制中占有非常重要的地位。测压的方式有很多，但每一种测压方式均需要对测量设备进行校准，以期获得测量数据，如电信号、光信号等与压力之间的函数关系以及测量系统如灵敏度等的特性。As one of the three thermal parameters of automatic control (pressure, temperature, flow), pressure occupies a very important position in measurement and control. There are many ways of pressure measurement, but each pressure measurement method requires calibration of the measuring equipment in order to obtain measurement data, such as the functional relationship between electrical signals, optical signals, etc. and pressure, and the characteristics of the measurement system such as sensitivity.

基于计算机视觉与图像处理技术的光学压敏涂料测压技术(Pressure SensitivePaint，PSP)，是非接触式流动显示技术的重要突破。与目前国内传统的点阵式测量技术相比，光学压敏测量技术能够弥补压力探针布孔、压力传感器等对模型的破坏和对流场的干扰以及传统方法数据传输方式的复杂性，并且该测量技术大幅度提升测量范围，具有无接触、连续测量、试验成本相对低廉、节约时间等优势，已经受到广大实验工作者的青睐。光学压敏测压技术的基本原理为：将压力敏感涂料均匀覆盖于被测模型表面，压力敏感涂料由光敏分子和可以透氧的基质组成。在受到特定波长的光激发时，涂料中的光敏分子由原本稳定的基态获得能量而跃迁到高能级的激发态。处于不稳定激发态的光敏分子，受到被测量表面扩散进来的氧分子碰撞，失去激发态的能量而失活回到基态，这种过程并不产生辐射光，从而导致发光强度降低，形成“氧猝灭”现象。氧分子浓度越大，即：在大气中可视为压力越大，氧的猝灭效应越强，涂料在一定光光照下发出的光就越暗。因此，在光照射下，压力敏感涂料的发光强度即可反映被测模型表面所受的压力值。在光照射下拍摄被测模型表面的图像照片，通过对图像照片进行分析，可得到被测模型表面的压力分布。光学压敏测压需通过预先校准的方式来获得涂料特性。Optical pressure-sensitive paint pressure measurement technology (Pressure Sensitive Paint, PSP) based on computer vision and image processing technology is an important breakthrough in non-contact flow display technology. Compared with the current domestic traditional dot-matrix measurement technology, the optical pressure-sensitive measurement technology can make up for the damage to the model and the interference to the flow field caused by the arrangement of pressure probes and pressure sensors, as well as the complexity of the traditional method of data transmission, and This measurement technology greatly improves the measurement range, and has the advantages of non-contact, continuous measurement, relatively low test cost, and time saving, and has been favored by the majority of experimental workers. The basic principle of the optical pressure-sensitive manometry technology is: the pressure-sensitive paint is uniformly covered on the surface of the tested model, and the pressure-sensitive paint is composed of photosensitive molecules and oxygen-permeable matrix. When excited by light of a specific wavelength, the photosensitive molecules in the coating obtain energy from the originally stable ground state and transition to the excited state of high energy level. The photosensitive molecules in the unstable excited state are collided by the oxygen molecules diffused from the surface to be measured, lose the energy of the excited state and inactivate back to the ground state. Quenching" phenomenon. The greater the concentration of oxygen molecules, that is, the greater the pressure in the atmosphere, the stronger the quenching effect of oxygen, and the darker the light emitted by the paint under certain light illumination. Therefore, under light irradiation, the luminous intensity of the pressure-sensitive paint can reflect the pressure value on the surface of the tested model. An image photo of the surface of the tested model is taken under light irradiation, and the pressure distribution on the surface of the tested model can be obtained by analyzing the image photo. Optical pressure-sensitive manometry needs to be pre-calibrated to obtain coating properties.

现有技术中，光学压敏涂料幅频特性检测技术主要存在以下问题：In the prior art, the detection technology of amplitude-frequency characteristics of optical pressure-sensitive coatings mainly has the following problems:

在光学压敏涂料幅频特性检测过程中，为获得全域的动态压力分布，必须通过相机完成图像的采集，而由于CCD相机的帧率较低，在采集高频脉动压力下的压力敏感涂料荧光图像序列时，会引入较大的系统误差，从而降低了光学压敏涂料幅频特性检测准确度。In the process of detecting the amplitude-frequency characteristics of optical pressure-sensitive coatings, in order to obtain the dynamic pressure distribution of the whole field, the image acquisition must be completed by the camera. However, due to the low frame rate of the CCD camera, the fluorescence of the pressure-sensitive coating under the high-frequency pulsating pressure is collected. When the image sequence is used, a large systematic error will be introduced, thereby reducing the detection accuracy of the amplitude-frequency characteristics of the optical pressure-sensitive paint.

发明内容SUMMARY OF THE INVENTION

针对现有技术存在的缺陷，本发明提供一种基于CCD相机的光学压敏涂料幅频特性检测方法，可有效解决上述问题。In view of the defects existing in the prior art, the present invention provides a method for detecting the amplitude-frequency characteristics of an optical pressure-sensitive paint based on a CCD camera, which can effectively solve the above problems.

本发明采用的技术方案如下：The technical scheme adopted in the present invention is as follows:

本发明提供一种基于CCD相机的光学压敏涂料幅频特性检测方法，包括以下步骤：The invention provides a method for detecting amplitude-frequency characteristics of optical pressure-sensitive paint based on a CCD camera, comprising the following steps:

步骤1，将PSP样片(2)固定于声学驻波管(1)的底盖位置，在声学驻波管(1)旋紧后，底盖所在平面与声源(11)所在平面平行；信号发生器(8)的第1通道通过功率放大器(9)与声源(11)连接，声源(11)的发声端与声学驻波管(1)连接；Step 1: Fix the PSP sample (2) at the position of the bottom cover of the acoustic standing wave tube (1). After the acoustic standing wave tube (1) is tightened, the plane where the bottom cover is located is parallel to the plane where the sound source (11) is located; the signal The first channel of the generator (8) is connected to the sound source (11) through the power amplifier (9), and the sounding end of the sound source (11) is connected to the acoustic standing wave tube (1);

CCD相机(5)和激光光源(3)经声学驻波管(1)的光学视窗(7)对准PSP样片(2)，在CCD相机(5)的镜头前固定安装滤光片(6)；信号发生器(8)的第2通道与CCD相机(5)连接；信号发生器(8)的第3通道与激光光源(3)连接；The CCD camera (5) and the laser light source (3) are aligned with the PSP sample (2) through the optical window (7) of the acoustic standing wave tube (1), and a filter (6) is fixedly installed in front of the lens of the CCD camera (5). ; The second channel of the signal generator (8) is connected with the CCD camera (5); the third channel of the signal generator (8) is connected with the laser light source (3);

在PSP样片(2)所在截面固定动态压力传感器(4)；A dynamic pressure sensor (4) is fixed on the section where the PSP sample (2) is located;

所述CCD相机(5)的输出端和所述动态压力传感器(4)的输出端均连接到计算机(10)；Both the output end of the CCD camera (5) and the output end of the dynamic pressure sensor (4) are connected to a computer (10);

相机、光源经光学视窗对准PSP样片，在PSP样片所在截面固定动态压力传感器用于实时动态压力测量并提供触发信号；The camera and light source are aligned with the PSP sample through the optical window, and a dynamic pressure sensor is fixed on the section where the PSP sample is located for real-time dynamic pressure measurement and providing trigger signals;

步骤2，从t＝0开始，同时启动信号发生器(8)和动态压力传感器(4)；其中，所述动态压力传感器(4)实时测量PSP样片(2)表面所受到的真实压力值，并将PSP样片(2)表面所受到的真实压力值传给所述计算机(10)，由此使所述计算机(10)得到PSP样片(2)表面所受到的真实压力值与时间之间的变化曲线；Step 2, starting from t=0, start the signal generator (8) and the dynamic pressure sensor (4) at the same time; wherein, the dynamic pressure sensor (4) measures the real pressure value on the surface of the PSP sample (2) in real time, and transmit the real pressure value on the surface of the PSP sample (2) to the computer (10), so that the computer (10) obtains the difference between the real pressure value on the surface of the PSP sample (2) and the time. Curve;

所述信号发生器(8)连续输出周期为T1、频率为f1的正弦信号，该正弦信号传递到功率放大器(9)，由功率放大器(9)驱动声源(11)发出周期为T1、频率为f1的正弦声波；The signal generator (8) continuously outputs a sinusoidal signal with a period of T 1 and a frequency of f 1 , the sinusoidal signal is transmitted to the power amplifier (9), and the sound source (11) is driven by the power amplifier (9) to emit a period of T 1 . 1. A sinusoidal sound wave with a frequency of f 1 ;

该正弦声波经声学驻波管(1)作用，从而使PSP样片(2)表面受到稳定的周期为T1、频率为f1的正弦压力驻波；The sinusoidal sound wave is acted on by the acoustic standing wave tube (1), so that the surface of the PSP sample (2) is subjected to a stable sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 ;

步骤3，信号发生器(8)连接激光光源(3)的外触发接口，对激光光源(3)的工作状态进行控制；同时，信号发生器(8)连接CCD相机(5)的外触发接口，对CCD相机(5)的工作状态进行控制；具体控制方式为：Step 3, the signal generator (8) is connected to the external trigger interface of the laser light source (3) to control the working state of the laser light source (3); at the same time, the signal generator (8) is connected to the external trigger interface of the CCD camera (5) , to control the working state of the CCD camera (5); the specific control method is:

步骤3.1，对于周期为T1、频率为f1的正弦压力驻波，将一个正弦压力驻波平均划分为n个相位，依次表示为相位

Figure GDA0003503278800000031
相位
Figure GDA0003503278800000032
相位
Figure GDA0003503278800000033
相邻相位之间的时间间隔均为
Figure GDA0003503278800000034
Step 3.1, for a sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 , divide a sinusoidal pressure standing wave into n phases on average, which are expressed as phases in turn
Figure GDA0003503278800000031
phase
Figure GDA0003503278800000032
phase
Figure GDA0003503278800000033
The time interval between adjacent phases is
Figure GDA0003503278800000034

预设置CCD相机每次的曝光时间te；其中，te≤T1/(n-1)；Preset the exposure time t e of the CCD camera each time; wherein, t e ≤ T 1 /(n-1);

根据CCD相机的帧率，预设置CCD相机的拍摄时间间隔TC＝m×T1+T1/(n-1)；其中，m表示相机拍摄周期间隔的数量；相机的拍摄时间间隔TC大于相机最大帧率的倒数；According to the frame rate of the CCD camera, the shooting time interval T C =m×T 1 +T 1 /(n-1) of the CCD camera is preset; where m represents the number of camera shooting period intervals; the shooting time interval T C of the camera Greater than the inverse of the camera's maximum frame rate;

步骤3.2，在t＝tk时刻，正弦压力驻波为第1个周期中相位

Figure GDA0003503278800000041
的状态；信号发生器(8)同时控制激光光源(3)打开以及CCD相机(5)打开；Step 3.2, at time t = tk, the sinusoidal pressure standing wave is the phase in the first cycle
Figure GDA0003503278800000041
The signal generator (8) simultaneously controls the laser light source (3) to turn on and the CCD camera (5) to turn on;

此时，激光光源(3)打开后，进入长打开模式，即：激光光源(3)打开后，保持稳定功率连续发光照射PSP样片(2)表面，从而激发PSP涂料；At this time, after the laser light source (3) is turned on, it enters the long-on mode, that is, after the laser light source (3) is turned on, the surface of the PSP sample (2) is irradiated with continuous light emission at a stable power, thereby exciting the PSP coating;

CCD相机(5)打开后，进行第1次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+te时，关闭CCD相机(5)；此时，CCD相机(5)输出与相位

Figure GDA0003503278800000049
对应的荧光图像Q1；After the CCD camera (5) is turned on, the first exposure is performed, and the exposure time is t e ; when the exposure time is reached, that is: when t=t k +t e , the CCD camera (5) is turned off; at this time, the CCD camera (5) Output and phase
Figure GDA0003503278800000049
the corresponding fluorescence image Q 1 ;

步骤3.3，从相机第1次曝光起始时间开始，即从t＝tk时刻开始算起，经过CCD相机的拍摄时间间隔TC后，即：t＝tk+m×T1+T1/(n-1)时，此时正弦压力驻波为第m+1个周期中相位

Figure GDA00035032788000000410
的状态，此时打开CCD相机(5)，进行第2次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+m×T1+T1/(n-1)+te时，关闭CCD相机(5)；此时，CCD相机(5)输出与相位
Figure GDA0003503278800000042
对应的荧光图像Q2；Step 3.3, starting from the start time of the first exposure of the camera, that is, counting from the moment t = tk , after the shooting time interval TC of the CCD camera, namely: t = tk+m × T1 + T1 /(n-1), the sinusoidal pressure standing wave is the phase in the m+1th cycle
Figure GDA00035032788000000410
state, turn on the CCD camera (5) at this time, and perform the second exposure, the exposure time is t e ; when the exposure time is reached, that is: when t=t k +m×T 1 +T 1 /(n-1 )+t e , turn off the CCD camera (5); at this time, the output of the CCD camera (5) and the phase
Figure GDA0003503278800000042
the corresponding fluorescence image Q 2 ;

步骤3.4，从相机第2次曝光起始时间开始，经过CCD相机的拍摄时间间隔TC后，此时正弦压力驻波为第2m+1个周期中相位

Figure GDA0003503278800000043
的状态，打开CCD相机(5)进行第3次曝光，CCD相机(5)输出与相位
Figure GDA0003503278800000044
对应的荧光图像Q3；Step 3.4, starting from the start time of the second exposure of the camera, after the shooting time interval TC of the CCD camera, the sinusoidal pressure standing wave is the phase in the 2m+1 cycle at this time .
Figure GDA0003503278800000043
state, turn on the CCD camera (5) for the third exposure, the output of the CCD camera (5) and the phase
Figure GDA0003503278800000044
the corresponding fluorescence image Q 3 ;

依此类推，在激光光源(3)保持稳定功率连续发光照射PSP样片(2)表面的过程中，每隔CCD相机的拍摄时间间隔TC，CCD相机(5)曝光一次，并输出与正弦压力驻波当前相位对应的荧光图像；直到CCD相机(5)输出与最后一个相位

Figure GDA0003503278800000045
对应的荧光图像Qn；By analogy, in the process that the laser light source (3) maintains a stable power and continuously emits light on the surface of the PSP sample (2), the CCD camera (5) is exposed once every shooting time interval T C of the CCD camera, and the output and the sinusoidal pressure are outputted. The fluorescence image corresponding to the current phase of the standing wave; until the output of the CCD camera (5) is the same as the last phase
Figure GDA0003503278800000045
the corresponding fluorescence image Q n ;

至此，当正弦压力驻波频率为f1时，得到一个完整周期对应的荧光图像序列，分别为：与相位

Figure GDA0003503278800000046
对应的荧光图像Q1，与相位
Figure GDA0003503278800000047
对应的荧光图像Q2,…,与相位
Figure GDA0003503278800000048
对应的荧光图像Qn；So far, when the frequency of the sinusoidal pressure standing wave is f 1 , a sequence of fluorescence images corresponding to a complete cycle is obtained, which are:
Figure GDA0003503278800000046
Corresponding fluorescence image Q 1 , with phase
Figure GDA0003503278800000047
Corresponding fluorescence images Q 2 , . . . , and phase
Figure GDA0003503278800000048
the corresponding fluorescence image Q n ;

步骤4，对于每一个荧光图像Qj，j＝1,2,...,n，均采用以下方式处理：Step 4, for each fluorescence image Q j , j=1, 2, . . . n, are processed in the following manner:

步骤4.1，对荧光图像Qj进行图像处理，得到与相位

Figure GDA0003503278800000051
对应的光强Ij；Step 4.1, perform image processing on the fluorescence image Q j to obtain the phase
Figure GDA0003503278800000051
the corresponding light intensity I j ;

步骤4.2，获取荧光图像Qj获取过程中，CCD相机(5)的曝光时间，再根据CCD相机(5)的曝光时间查找PSP样片(2)表面所受到的真实压力值与时间之间的变化曲线，得到荧光图像Qj对应的真实压力值Pj；Step 4.2, acquiring the fluorescence image Q j During the acquisition process, the exposure time of the CCD camera (5), and then according to the exposure time of the CCD camera (5) to find the change between the real pressure value and the time on the surface of the PSP sample (2) curve to obtain the real pressure value P j corresponding to the fluorescence image Q j ;

步骤4.3，在不向PSP样片(2)施加正弦压力驻波时，即：使PSP样片(2)处于大气压力下，并对PSP样片(2)进行图像拍摄，从而得到参考压力Pref和参考压力下的光强Iref；Step 4.3, when the sine pressure standing wave is not applied to the PSP sample (2), that is: the PSP sample (2) is under atmospheric pressure, and the image of the PSP sample (2) is photographed, thereby obtaining the reference pressure P ref and reference Light intensity I ref under pressure;

步骤5，将光强Ij、真实压力值Pj、参考压力Pref和参考压力下的光强Iref代入以下校准方程(1)：Step 5: Substitute the light intensity I j , the real pressure value P j , the reference pressure P ref and the light intensity I ref under the reference pressure into the following calibration equation (1):

Figure GDA0003503278800000052
Figure GDA0003503278800000052

由于j＝1,2,...,n，因此，当j＝1时，得到关于A和B的一个方程；当j＝2时，得到关于A和B的一个方程；依此类推，当j＝n时，得到关于A和B的一个方程；因此，共得到n个关于A和B的方程；对n个关于A和B的方程，采用最小二乘法求解，得到最终的A和B的值；Since j=1,2,...,n, when j=1, one equation for A and B is obtained; when j=2, one equation for A and B is obtained; and so on, when When j=n, one equation about A and B is obtained; therefore, a total of n equations about A and B are obtained; for n equations about A and B, the least squares method is used to solve the final equations of A and B. value;

A和B均为常数，将A和B的值、参考压力Pref和参考压力下的光强Iref代入校准方程(1)，得到校准方程(2)：Both A and B are constants. Substitute the values of A and B, the reference pressure P ref and the light intensity I ref under the reference pressure into the calibration equation (1) to obtain the calibration equation (2):

Figure GDA0003503278800000053
Figure GDA0003503278800000053

其中，在校准方程(2)中，P'j为与光强Ij对应的校准压力值；Wherein, in the calibration equation (2), P' j is the calibration pressure value corresponding to the light intensity I j ;

步骤6，对于每一个荧光图像Qj，j＝1,2,...,n，均对应相位

Figure GDA0003503278800000054
的值以及光强Ij的值；将光强Ij代入稳态校准后的方程(2)，得到对应的校准压力值Pj'；因此，得到相位
Figure GDA0003503278800000055
和校准压力值Pj'的对应关系值；由于j＝1,2,...,n，因此，一共得到n组相位
Figure GDA0003503278800000061
和校准压力值Pj'的对应关系值；由此在横坐标为相位，纵坐标为校准压力值的坐标系中，绘制出n个离散点；将n个离散点拟合形成压力相位曲线；对压力相位曲线进行分析，得到幅值Am(f1)，其含义为：当正弦压力驻波频率为f1时，得到的幅值Am(f1)；Step 6, for each fluorescence image Q j , j=1,2,...,n, all corresponding to the phase
Figure GDA0003503278800000054
and the value of the light intensity I j ; substitute the light intensity I j into equation (2) after steady-state calibration to obtain the corresponding calibrated pressure value P j '; therefore, obtain the phase
Figure GDA0003503278800000055
and the corresponding relationship value of the calibration pressure value P j '; since j=1,2,...,n, a total of n groups of phases are obtained
Figure GDA0003503278800000061
and the corresponding relationship value of the calibration pressure value P j '; thus, in the coordinate system where the abscissa is the phase and the ordinate is the calibration pressure value, n discrete points are drawn; the n discrete points are fitted to form a pressure phase curve; Analyze the pressure phase curve to obtain the amplitude A m (f 1 ), which means: when the frequency of the sinusoidal pressure standing wave is f 1 , the obtained amplitude A m (f 1 );

步骤7，保持正弦压力驻波的幅值稳定不变，将正弦压力驻波频率从f1增大到f2，采用步骤2-步骤6的方式，得到对应的幅值Am(f2)；判断幅值Am(f2)是否降低为幅值Am(f1)的一半，如果是，则幅值Am(f2)为PSP涂料的截止频率；如果否，则进一步增大正弦压力驻波频率，直到使当前频率fx下的幅值Am(fx)降低为幅值Am(f1)的一半时为止，此时，当前频率fx为PSP涂料的截止频率；Step 7: Keep the amplitude of the sine pressure standing wave stable, increase the frequency of the sine pressure standing wave from f 1 to f 2 , and obtain the corresponding amplitude A m (f 2 ) by adopting the method of step 2 to step 6 ; Determine whether the amplitude A m (f 2 ) is reduced to half of the amplitude A m (f 1 ), if so, the amplitude A m (f 2 ) is the cut-off frequency of the PSP paint; if not, further increase Sine pressure standing wave frequency, until the amplitude Am ( f x ) at the current frequency f x is reduced to half of the amplitude Am ( f 1 ), at this time, the current frequency f x is the cutoff frequency of the PSP paint ;

不断增大正弦压力驻波频率，如果当前频率fz下的幅值Am(fz)降为0，则当前频率fz为PSP涂料的极限频率；由此实现对PSP涂料的幅频特性的检测。Continuously increase the frequency of the sine pressure standing wave, if the amplitude Am ( f z ) under the current frequency f z drops to 0, then the current frequency f z is the limit frequency of the PSP paint; thereby realizing the amplitude-frequency characteristics of the PSP paint detection.

优选的，步骤4.1具体为：Preferably, step 4.1 is specifically:

荧光图像Qj具有w个像素点；每个像素点均对应一个光强值，因此，共得到w个光强值，对w个光强值求平均值，即为与相位

Figure GDA0003503278800000062
对应的光强Ij。The fluorescence image Q j has w pixels; each pixel corresponds to a light intensity value, therefore, a total of w light intensity values are obtained, and the average value of the w light intensity values is
Figure GDA0003503278800000062
The corresponding light intensity I j .

本发明提供的一种基于CCD相机的光学压敏涂料幅频特性检测方法具有以下优点：A CCD camera-based method for detecting amplitude-frequency characteristics of optical pressure-sensitive coatings provided by the present invention has the following advantages:

本发明通过对CCD相机的时序进行控制，通过低帧率CCD相机采集高频脉动压力下的压力敏感涂料荧光图像序列，从而获得全域的动态压力分布，通过本发明方法，有效降低了系统误差，从而提高了光学压敏涂料幅频特性检测准确度。The invention controls the sequence of the CCD camera, collects the pressure-sensitive paint fluorescence image sequence under the high-frequency pulsating pressure through the low frame rate CCD camera, so as to obtain the dynamic pressure distribution in the whole area, and the method of the invention effectively reduces the system error, Thus, the detection accuracy of the amplitude-frequency characteristic of the optical pressure-sensitive coating is improved.

附图说明Description of drawings

图1为本发明提供的基于CCD相机的光学压敏涂料幅频特性检测系统的结构示意图；Fig. 1 is the structural representation of the amplitude-frequency characteristic detection system of optical pressure-sensitive paint based on CCD camera provided by the present invention;

图2为本发明提供的CCD相机的控制时序示意图。FIG. 2 is a schematic diagram of the control sequence of the CCD camera provided by the present invention.

具体实施方式Detailed ways

为了使本发明所解决的技术问题、技术方案及有益效果更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

本发明通过低帧率的CCD相机，基于相位锁定法采集在相同幅值不同频率的正弦压力波动下光学压敏涂料发出的荧光图像，获取光强的脉动，依据测得涂料在不同频率下的光强转化压力后幅值，获得涂料的幅频特性，主要用于压力敏感涂料动态压力校准。The invention collects the fluorescent images emitted by the optical pressure-sensitive paint under the sinusoidal pressure fluctuations of the same amplitude and different frequencies through a CCD camera with a low frame rate based on the phase locking method, and obtains the pulsation of the light intensity. The amplitude of the light intensity is converted into the pressure to obtain the amplitude-frequency characteristics of the paint, which is mainly used for the dynamic pressure calibration of the pressure-sensitive paint.

本发明提供一种基于CCD相机的光学压敏涂料幅频特性检测方法，包括以下步骤：The invention provides a method for detecting amplitude-frequency characteristics of optical pressure-sensitive paint based on a CCD camera, comprising the following steps:

步骤1，参考图1，将PSP样片2固定于声学驻波管1的底盖位置，在声学驻波管1旋紧后，底盖所在平面与声源11所在平面平行；信号发生器8的第1通道通过功率放大器9与声源11连接，声源11的发声端与声学驻波管1连接；Step 1, referring to FIG. 1, fix the PSP sample 2 on the bottom cover of the acoustic standing wave tube 1. After the acoustic standing wave tube 1 is tightened, the plane where the bottom cover is located is parallel to the plane where the sound source 11 is located; The first channel is connected to the sound source 11 through the power amplifier 9, and the sounding end of the sound source 11 is connected to the acoustic standing wave tube 1;

CCD相机5和激光光源3经声学驻波管1的光学视窗7对准PSP样片2，在CCD相机5的镜头前固定安装滤光片6；信号发生器8的第2通道与CCD相机5连接；信号发生器8的第3通道与激光光源3连接；The CCD camera 5 and the laser light source 3 are aligned with the PSP sample 2 through the optical window 7 of the acoustic standing wave tube 1, and the filter 6 is fixedly installed in front of the lens of the CCD camera 5; the second channel of the signal generator 8 is connected with the CCD camera 5 ; The third channel of the signal generator 8 is connected to the laser light source 3;

在PSP样片2所在截面固定动态压力传感器4；Fix the dynamic pressure sensor 4 on the section where the PSP sample 2 is located;

所述CCD相机5的输出端和所述动态压力传感器4的输出端均连接到计算机10；The output end of the CCD camera 5 and the output end of the dynamic pressure sensor 4 are both connected to the computer 10;

相机、光源经光学视窗对准PSP样片，在PSP样片所在截面固定动态压力传感器用于实时动态压力测量并提供触发信号；The camera and light source are aligned with the PSP sample through the optical window, and a dynamic pressure sensor is fixed on the section where the PSP sample is located for real-time dynamic pressure measurement and providing trigger signals;

步骤2，从t＝0开始，同时启动信号发生器8和动态压力传感器4；其中，所述动态压力传感器4实时测量PSP样片2表面所受到的真实压力值，并将PSP样片2表面所受到的真实压力值传给所述计算机10，由此使所述计算机10得到PSP样片2表面所受到的真实压力值与时间之间的变化曲线；Step 2, starting from t=0, start the signal generator 8 and the dynamic pressure sensor 4 at the same time; wherein, the dynamic pressure sensor 4 measures the real pressure value on the surface of the PSP sample 2 in real time, and calculates the value of the real pressure on the surface of the PSP sample 2. The real pressure value is transmitted to the computer 10, so that the computer 10 can obtain the change curve between the real pressure value and the time on the surface of the PSP sample 2;

所述信号发生器8连续输出周期为T1、频率为f1的正弦信号，该正弦信号传递到功率放大器9，由功率放大器9驱动声源11发出周期为T1、频率为f1的正弦声波；The signal generator 8 continuously outputs a sine signal with a period of T 1 and a frequency of f 1. The sine signal is transmitted to the power amplifier 9, and the sound source 11 is driven by the power amplifier 9 to issue a sine signal with a period of T 1 and a frequency of f 1 . sound waves;

该正弦声波经声学驻波管1作用，从而使PSP样片2表面受到稳定的周期为T1、频率为f1的正弦压力驻波；The sinusoidal sound wave is acted on by the acoustic standing wave tube 1, so that the surface of the PSP sample 2 is subjected to a stable sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 ;

步骤3，信号发生器8连接激光光源3的外触发接口，对激光光源3的工作状态进行控制；同时，信号发生器8连接CCD相机5的外触发接口，对CCD相机5的工作状态进行控制；具体控制方式为：Step 3, the signal generator 8 is connected to the external trigger interface of the laser light source 3 to control the working state of the laser light source 3; at the same time, the signal generator 8 is connected to the external trigger interface of the CCD camera 5 to control the working state of the CCD camera 5 ; The specific control method is:

步骤3.1，对于周期为T1、频率为f1的正弦压力驻波，将一个正弦压力驻波平均划分为n个相位，依次表示为相位

Figure GDA0003503278800000081
相位
Figure GDA0003503278800000082
相位
Figure GDA0003503278800000083
相邻相位之间的时间间隔均为
Figure GDA0003503278800000084
Step 3.1, for a sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 , divide a sinusoidal pressure standing wave into n phases on average, which are expressed as phases in turn
Figure GDA0003503278800000081
phase
Figure GDA0003503278800000082
phase
Figure GDA0003503278800000083
The time interval between adjacent phases is
Figure GDA0003503278800000084

预设置CCD相机每次的曝光时间te；其中，te≤T1/(n-1)；Preset the exposure time t e of the CCD camera each time; wherein, t e ≤ T 1 /(n-1);

根据CCD相机的帧率，预设置CCD相机的拍摄时间间隔TC＝m×T1+T1/(n-1)；其中，m表示相机拍摄周期间隔的数量；相机的拍摄时间间隔TC大于相机最大帧率的倒数；According to the frame rate of the CCD camera, the shooting time interval T C =m×T 1 +T 1 /(n-1) of the CCD camera is preset; where m represents the number of camera shooting period intervals; the shooting time interval T C of the camera Greater than the inverse of the camera's maximum frame rate;

步骤3.2，在t＝tk时刻，正弦压力驻波为第1个周期中相位

Figure GDA0003503278800000085
的状态；信号发生器8同时控制激光光源3打开以及CCD相机5打开；Step 3.2, at time t = tk, the sinusoidal pressure standing wave is the phase in the first cycle
Figure GDA0003503278800000085
The signal generator 8 simultaneously controls the laser light source 3 to open and the CCD camera 5 to open;

此时，激光光源3打开后，进入长打开模式，即：激光光源3打开后，保持稳定功率连续发光照射PSP样片2表面，从而激发PSP涂料；At this time, after the laser light source 3 is turned on, it enters the long-on mode, that is, after the laser light source 3 is turned on, the surface of the PSP sample 2 is irradiated with continuous light emission at a stable power, thereby exciting the PSP coating;

CCD相机5打开后，进行第1次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+te时，关闭CCD相机5；此时，CCD相机5输出与相位

Figure GDA0003503278800000091
对应的荧光图像Q1；After the CCD camera 5 is turned on, the first exposure is performed, and the exposure time is t e ; when the exposure time is reached, that is: when t=t k + t e , the CCD camera 5 is turned off; at this time, the CCD camera 5 outputs and the phase
Figure GDA0003503278800000091
the corresponding fluorescence image Q 1 ;

步骤3.3，从相机第1次曝光起始时间开始，即从t＝tk时刻开始算起，经过CCD相机的拍摄时间间隔TC后，即：t＝tk+m×T1+T1/(n-1)时，此时正弦压力驻波为第m+1个周期中相位

Figure GDA0003503278800000092
的状态，此时打开CCD相机5，进行第2次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+m×T1+T1/(n-1)+te时，关闭CCD相机5；此时，CCD相机5输出与相位
Figure GDA0003503278800000093
对应的荧光图像Q2；Step 3.3, starting from the start time of the first exposure of the camera, that is, counting from the moment t = tk , after the shooting time interval TC of the CCD camera, namely: t = tk+m × T1 + T1 /(n-1), the sinusoidal pressure standing wave is the phase in the m+1th cycle
Figure GDA0003503278800000092
At this time, the CCD camera 5 is turned on, and the second exposure is performed, and the exposure time is t e ; when the exposure time is reached, that is: when t=t k +m×T 1 +T 1 /(n-1)+ At t e , turn off the CCD camera 5; at this time, the output of the CCD camera 5 and the phase
Figure GDA0003503278800000093
the corresponding fluorescence image Q 2 ;

步骤3.4，从相机第2次曝光起始时间开始，经过CCD相机的拍摄时间间隔TC后，此时正弦压力驻波为第2m+1个周期中相位

Figure GDA0003503278800000094
的状态，打开CCD相机5进行第3次曝光，CCD相机5输出与相位
Figure GDA0003503278800000095
对应的荧光图像Q3；Step 3.4, starting from the start time of the second exposure of the camera, after the shooting time interval TC of the CCD camera, the sinusoidal pressure standing wave is the phase in the 2m+1 cycle at this time .
Figure GDA0003503278800000094
state, turn on the CCD camera 5 for the third exposure, the output of the CCD camera 5 and the phase
Figure GDA0003503278800000095
the corresponding fluorescence image Q 3 ;

依此类推，在激光光源3保持稳定功率连续发光照射PSP样片2表面的过程中，每隔CCD相机的拍摄时间间隔TC，CCD相机5曝光一次，并输出与正弦压力驻波当前相位对应的荧光图像；直到CCD相机5输出与最后一个相位

Figure GDA0003503278800000096
对应的荧光图像Qn；By analogy, in the process that the laser light source 3 maintains a stable power and continuously emits light on the surface of the PSP sample 2, the CCD camera 5 is exposed once every shooting time interval T C of the CCD camera, and outputs the current phase corresponding to the sinusoidal pressure standing wave. Fluorescence image; until CCD camera 5 outputs and last phase
Figure GDA0003503278800000096
the corresponding fluorescence image Q n ;

至此，当正弦压力驻波频率为f1时，得到一个完整周期对应的荧光图像序列，分别为：与相位

Figure GDA0003503278800000097
对应的荧光图像Q1，与相位
Figure GDA0003503278800000098
对应的荧光图像Q2,…,与相位
Figure GDA0003503278800000099
对应的荧光图像Qn；So far, when the frequency of the sinusoidal pressure standing wave is f 1 , a sequence of fluorescence images corresponding to a complete cycle is obtained, which are:
Figure GDA0003503278800000097
Corresponding fluorescence image Q 1 , with phase
Figure GDA0003503278800000098
Corresponding fluorescence images Q 2 , . . . , and phase
Figure GDA0003503278800000099
the corresponding fluorescence image Q n ;

为方便对步骤3.1-步骤3.4进行理解，下面结合图2，列举一个实施例：In order to facilitate the understanding of steps 3.1 to 3.4, an embodiment is listed below in conjunction with Figure 2:

假设正弦压力驻波的周期T1为1s，其中，s为单位秒；将一个正弦压力驻波平均划分为n＝5个相位，分别为：相位

Figure GDA00035032788000000910
相位
Figure GDA00035032788000000911
相位
Figure GDA00035032788000000912
相位
Figure GDA00035032788000000913
相位
Figure GDA00035032788000000914
相邻相位之间的时间间隔为
Figure GDA00035032788000000915
当然，实际应用中，可以根据实际需求，将一个正弦压力驻波平均划分为10个相位，20个相位等，本发明对此并不限制。Assume that the period T 1 of the sinusoidal pressure standing wave is 1s, where s is the unit of second; divide a sinusoidal pressure standing wave into n=5 phases on average, which are: phase
Figure GDA00035032788000000910
phase
Figure GDA00035032788000000911
phase
Figure GDA00035032788000000912
phase
Figure GDA00035032788000000913
phase
Figure GDA00035032788000000914
The time interval between adjacent phases is
Figure GDA00035032788000000915
Of course, in practical applications, a sinusoidal pressure standing wave can be divided into 10 phases, 20 phases, etc. on average according to actual requirements, which is not limited in the present invention.

预设置CCD相机每次的曝光时间te＝0.1s；Pre-set the exposure time t e =0.1s of the CCD camera each time;

预设置CCD相机的拍摄时间间隔TC＝m×T1+T1/(n-1)，假设m＝3，则TC＝3.25s；Preset the shooting time interval of the CCD camera T C =m×T 1 +T 1 /(n-1), assuming m=3, then T C =3.25s;

首先，在t＝tk时刻，此时的正弦压力驻波为第1个周期中相位

Figure GDA0003503278800000101
的状态，此时的第1个周期为相对周期，此时，信号发生器8同时控制激光光源3打开以及CCD相机5打开；First, at time t = tk, the sinusoidal pressure standing wave at this time is the phase in the first cycle
Figure GDA0003503278800000101
At this time, the first cycle is a relative cycle, and at this time, the signal generator 8 controls the laser light source 3 to turn on and the CCD camera 5 to turn on at the same time;

此时，激光光源3打开后，进入长打开模式，即：激光光源3打开后，保持稳定功率连续发光照射PSP样片2表面，从而激发PSP涂料；At this time, after the laser light source 3 is turned on, it enters the long-on mode, that is, after the laser light source 3 is turned on, the surface of the PSP sample 2 is irradiated with continuous light emission at a stable power, thereby exciting the PSP coating;

而CCD相机5打开后，进行第1次曝光，曝光时间为te＝0.1s；当达到曝光时间后，即：当t＝tk+0.1s时，关闭CCD相机5；此时，CCD相机5输出与相位

Figure GDA00035032788000001012
对应的荧光图像Q1；After the CCD camera 5 is turned on, the first exposure is performed, and the exposure time is t e =0.1s; when the exposure time is reached, that is, when t = tk +0.1s, the CCD camera 5 is turned off; at this time, the CCD camera 5 Output and Phase
Figure GDA00035032788000001012
the corresponding fluorescence image Q 1 ;

然后，经过TC＝3.25s后，此时正弦压力驻波为第4个周期中相位

Figure GDA0003503278800000102
的状态，打开CCD相机5，进行第2次曝光，CCD相机5输出与相位
Figure GDA0003503278800000103
对应的荧光图像Q2；Then, after T C =3.25s, the sinusoidal pressure standing wave is the phase in the fourth cycle
Figure GDA0003503278800000102
state, turn on the CCD camera 5, perform the second exposure, and the output of the CCD camera 5 and
Figure GDA0003503278800000103
the corresponding fluorescence image Q 2 ;

依此类推，每隔TC＝3.25s，CCD相机5进行一次曝光，从而相继输出与相位

Figure GDA0003503278800000104
对应的荧光图像Q3、与相位
Figure GDA0003503278800000105
对应的荧光图像Q4，与相位
Figure GDA0003503278800000106
对应的荧光图像Q5。By analogy, every T C =3.25s, the CCD camera 5 performs an exposure, so as to output and phase
Figure GDA0003503278800000104
The corresponding fluorescence image Q 3 , and the phase
Figure GDA0003503278800000105
Corresponding fluorescence image Q 4 , with phase
Figure GDA0003503278800000106
Corresponding fluorescence image Q5 .

由此可见，假如采用传统的方式，当将一个周期T1为1s的正弦压力驻波平均划分为n＝5个相位时，相邻相位之间的时间间隔为

Figure GDA0003503278800000107
因此，当到达一个正弦压力驻波时，理想情况下，相机需要以0.25s的帧率拍摄到5张荧光图像，即：相机在0～0.25s内完成一次曝光，输出与相位
Figure GDA0003503278800000108
对应的荧光图像Q1；然后，在0.25s～0.5s内完成一次曝光，输出与相位
Figure GDA0003503278800000109
对应的荧光图像Q2；依此类推，在1s～1.25s内完成一次曝光，输出与相位
Figure GDA00035032788000001010
对应的荧光图像Q5。而通常情况下，相机的帧率难以达到0.25s，因此，会引入较大的系统误差。It can be seen that if the traditional method is adopted, when a sinusoidal pressure standing wave with a period T 1 of 1s is divided into n=5 phases on average, the time interval between adjacent phases is
Figure GDA0003503278800000107
Therefore, when a sinusoidal pressure standing wave is reached, ideally, the camera needs to capture 5 fluorescence images at a frame rate of 0.25s, that is, the camera completes one exposure within 0-0.25s, and the output is the same as the phase.
Figure GDA0003503278800000108
The corresponding fluorescence image Q 1 ; then, an exposure is completed within 0.25s～0.5s, and the output and phase
Figure GDA0003503278800000109
Corresponding fluorescence image Q 2 ; and so on, complete an exposure within 1s～1.25s, the output and phase
Figure GDA00035032788000001010
Corresponding fluorescence image Q5 . Under normal circumstances, the frame rate of the camera is difficult to reach 0.25s, so a large system error will be introduced.

而本发明中，在相机在0～0.25s内完成一次曝光，输出与相位

Figure GDA00035032788000001013
对应的荧光图像Q1；然后，经过TC＝3.25s的时间间隔，相机在3.25s～3.5s内完成一次曝光，输出与相位
Figure GDA00035032788000001011
对应的荧光图像Q2；依此类推，每隔TC＝3.25s的时间间隔，相机才进行一次曝光，并输出与对应相位对应的荧光图像。从而同样完成一个周期相位对应的荧光图像的采集。并且，实际应用中，根据相机帧率的实际情况，可以调节时间间隔的具体数值。因此，本发明通过低帧率的CCD相机，采集高频脉动压力下的压力敏感涂料荧光图像序列，避免相机帧率低而引入的误差，提高了光学压敏涂料幅频特性检测准确度。另外，采用本发明的图像采集方式，可避免数据存储/传递拥塞，保证数据存储和传输的顺畅性。In the present invention, the camera completes one exposure within 0-0.25s, and the output and phase
Figure GDA00035032788000001013
The corresponding fluorescence image Q 1 ; then, after the time interval of T C =3.25s, the camera completes one exposure within 3.25s～3.5s, and the output and phase
Figure GDA00035032788000001011
Corresponding fluorescence image Q 2 ; and so on, every time interval of TC = 3.25s , the camera only performs one exposure, and outputs the fluorescence image corresponding to the corresponding phase. Thus, the acquisition of a fluorescence image corresponding to a period phase is also completed. Moreover, in practical applications, the specific value of the time interval can be adjusted according to the actual situation of the camera frame rate. Therefore, the present invention collects the fluorescence image sequence of the pressure-sensitive paint under the high-frequency pulsating pressure through a CCD camera with a low frame rate, avoids errors introduced by the low frame rate of the camera, and improves the detection accuracy of the amplitude-frequency characteristic of the optical pressure-sensitive paint. In addition, by adopting the image acquisition method of the present invention, data storage/transmission congestion can be avoided, and smoothness of data storage and transmission can be ensured.

步骤4，对于每一个荧光图像Qj，j＝1,2,...,n，均采用以下方式处理：Step 4, for each fluorescence image Q j , j=1, 2, . . . n, are processed in the following manner:

步骤4.1，对荧光图像Qj进行图像处理，得到与相位

Figure GDA0003503278800000111
对应的光强Ij；Step 4.1, perform image processing on the fluorescence image Q j to obtain the phase
Figure GDA0003503278800000111
the corresponding light intensity I j ;

步骤4.1具体为：Step 4.1 is as follows:

荧光图像Qj具有w个像素点；每个像素点均对应一个光强值，因此，共得到w个光强值，对w个光强值求平均值，即为与相位

Figure GDA0003503278800000112
对应的光强Ij。The fluorescence image Q j has w pixels; each pixel corresponds to a light intensity value, therefore, a total of w light intensity values are obtained, and the average value of the w light intensity values is
Figure GDA0003503278800000112
The corresponding light intensity I j .

步骤4.2，获取荧光图像Qj获取过程中，CCD相机5的曝光时间，再根据CCD相机5的曝光时间查找PSP样片2表面所受到的真实压力值与时间之间的变化曲线，得到荧光图像Qj对应的真实压力值Pj；Step 4.2: Acquiring the fluorescence image Q j . During the acquisition process, the exposure time of the CCD camera 5 is used, and then according to the exposure time of the CCD camera 5, the change curve between the real pressure value and time received by the surface of the PSP sample 2 is searched, and the fluorescence image Q is obtained. The real pressure value P j corresponding to j ;

步骤4.3，在不向PSP样片2施加正弦压力驻波时，即：使PSP样片2处于大气压力下，并对PSP样片2进行图像拍摄，从而得到参考压力Pref和参考压力下的光强Iref；Step 4.3, when the sine pressure standing wave is not applied to the PSP sample 2, namely: make the PSP sample 2 under atmospheric pressure, and photograph the PSP sample 2, thereby obtaining the reference pressure P ref and the light intensity I under the reference pressure ref ;

步骤5，将光强Ij、真实压力值Pj、参考压力Pref和参考压力下的光强Iref代入以下校准方程(1)：Step 5: Substitute the light intensity I j , the real pressure value P j , the reference pressure P ref and the light intensity I ref under the reference pressure into the following calibration equation (1):

Figure GDA0003503278800000113
Figure GDA0003503278800000113

由于j＝1,2,...,n，因此，当j＝1时，得到关于A和B的一个方程；当j＝2时，得到关于A和B的一个方程；依此类推，当j＝n时，得到关于A和B的一个方程；因此，共得到n个关于A和B的方程；对n个关于A和B的方程，采用最小二乘法求解，得到最终的A和B的值；Since j=1,2,...,n, when j=1, one equation for A and B is obtained; when j=2, one equation for A and B is obtained; and so on, when When j=n, one equation about A and B is obtained; therefore, a total of n equations about A and B are obtained; for n equations about A and B, the least squares method is used to solve the final equations of A and B. value;

A和B均为常数，将A和B的值、参考压力Pref和参考压力下的光强Iref代入校准方程(1)，得到校准方程(2)：Both A and B are constants. Substitute the values of A and B, the reference pressure P ref and the light intensity I ref under the reference pressure into the calibration equation (1) to obtain the calibration equation (2):

Figure GDA0003503278800000121
Figure GDA0003503278800000121

其中，在校准方程(2)中，P'j为与光强Ij对应的校准压力值；Wherein, in the calibration equation (2), P' j is the calibration pressure value corresponding to the light intensity I j ;

需要说明的是，校准方程(1)的主要作用为得到A和B的值，所以，校准方程(1)的压力为动态压力传感器4采集到的真实压力值Pj。而在得到A和B的值后，进一步得到校准方程(2)，校准方程(2)的主要作用为：计算得到与每张荧光图像对应的光强的校准压力值，因为此时计算得到的校准压力值是反应涂料特性的压力值，而并不采用动态压力传感器4采集到的真实压力值。It should be noted that the main function of the calibration equation (1) is to obtain the values of A and B, so the pressure of the calibration equation (1) is the real pressure value P j collected by the dynamic pressure sensor 4 . After the values of A and B are obtained, the calibration equation (2) is further obtained. The main function of the calibration equation (2) is to calculate the calibration pressure value of the light intensity corresponding to each fluorescence image, because the calculated value at this time The calibration pressure value is a pressure value reflecting the characteristics of the paint, and does not use the real pressure value collected by the dynamic pressure sensor 4 .

步骤6，对于每一个荧光图像Qj，j＝1,2,...,n，均对应相位

Figure GDA0003503278800000122
的值以及光强Ij的值；将光强Ij代入稳态校准后的方程(2)，得到对应的校准压力值Pj'；因此，得到相位
Figure GDA0003503278800000123
和校准压力值P'j的对应关系值；由于j＝1,2,...,n，因此，一共得到n组相位
Figure GDA0003503278800000124
和校准压力值P'j的对应关系值；由此在横坐标为相位，纵坐标为校准压力值的坐标系中，绘制出n个离散点；将n个离散点拟合形成压力相位曲线；对压力相位曲线进行分析，得到幅值Am(f1)，其含义为：当正弦压力驻波频率为f1时，得到的幅值Am(f1)；Step 6, for each fluorescence image Q j , j=1,2,...,n, all corresponding to the phase
Figure GDA0003503278800000122
and the value of the light intensity I j ; substitute the light intensity I j into equation (2) after steady-state calibration to obtain the corresponding calibrated pressure value P j '; therefore, obtain the phase
Figure GDA0003503278800000123
The corresponding relationship value with the calibration pressure value P'j; since j=1,2,...,n, therefore, a total of n groups of phases are obtained
Figure GDA0003503278800000124
and the corresponding relationship value of the calibration pressure value P'j ; thus, in the coordinate system where the abscissa is the phase and the ordinate is the calibration pressure value, n discrete points are drawn; the n discrete points are fitted to form a pressure phase curve; Analyze the pressure phase curve to obtain the amplitude A m (f 1 ), which means: when the frequency of the sinusoidal pressure standing wave is f 1 , the obtained amplitude A m (f 1 );

步骤7，保持正弦压力驻波的幅值稳定不变，将正弦压力驻波频率从f1增大到f2，采用步骤2-步骤6的方式，得到对应的幅值Am(f2)；判断幅值Am(f2)是否降低为幅值Am(f1)的一半，如果是，则幅值Am(f2)为PSP涂料的截止频率；如果否，则进一步增大正弦压力驻波频率，直到使当前频率fx下的幅值Am(fx)降低为幅值Am(f1)的一半时为止，此时，当前频率fx为PSP涂料的截止频率；Step 7: Keep the amplitude of the sine pressure standing wave stable, increase the frequency of the sine pressure standing wave from f 1 to f 2 , and obtain the corresponding amplitude A m (f 2 ) by adopting the method of step 2 to step 6 ; Determine whether the amplitude A m (f 2 ) is reduced to half of the amplitude A m (f 1 ), if so, the amplitude A m (f 2 ) is the cut-off frequency of the PSP paint; if not, further increase Sine pressure standing wave frequency, until the amplitude Am ( f x ) at the current frequency f x is reduced to half of the amplitude Am ( f 1 ), at this time, the current frequency f x is the cutoff frequency of the PSP paint ;

不断增大正弦压力驻波频率，如果当前频率fz下的幅值Am(fz)降为0，则当前频率fz为PSP涂料的极限频率；由此实现对PSP涂料的幅频特性的检测。Continuously increase the frequency of the sine pressure standing wave, if the amplitude Am ( f z ) under the current frequency f z drops to 0, then the current frequency f z is the limit frequency of the PSP paint; thereby realizing the amplitude-frequency characteristics of the PSP paint detection.

因此，本发明中，通过声学驻波管1得到频率、幅值稳定的正弦压力驻波；然后，根据正弦压力驻波的频率，对CCD相机的曝光时间和帧率进行控制，保证每次拍摄的图像对应正弦压力驻波的下一相位，从而使得到的图像序列刚好能够组成一个周期；在此过程中，激发光源保持稳定连续发光，CCD相机开启不同相位的图像序列采集。Therefore, in the present invention, a sinusoidal pressure standing wave with stable frequency and amplitude is obtained through the acoustic standing wave tube 1; then, according to the frequency of the sinusoidal pressure standing wave, the exposure time and frame rate of the CCD camera are controlled to ensure that each shooting The resulting image corresponds to the next phase of the sinusoidal pressure standing wave, so that the resulting image sequence can just form a cycle; during this process, the excitation light source remains stable and continuously emits light, and the CCD camera turns on the image sequence acquisition of different phases.

本发明提供一种基于CCD相机的光学压敏涂料幅频特性检测方法，具有以下优点：The invention provides a method for detecting amplitude-frequency characteristics of optical pressure-sensitive paint based on a CCD camera, which has the following advantages:

1、通过低帧率CCD相机采集高频脉动压力下的压力敏感涂料荧光图像序列；1. Collect the fluorescence image sequence of pressure-sensitive paint under high-frequency pulsating pressure through a low frame rate CCD camera;

2、保持正弦压力驻波幅值不变，通过改变正弦压力驻波频率，获取不同条件下的荧光图像序列，从而最终获得涂料的幅频特性，即：与正弦压力驻波的幅值对应的PSP涂料的截止频率和极限频率。2. Keep the amplitude of the sine pressure standing wave unchanged, and obtain the sequence of fluorescence images under different conditions by changing the frequency of the sine pressure standing wave, so as to finally obtain the amplitude-frequency characteristics of the paint, that is, the amplitude corresponding to the amplitude of the sine pressure standing wave. Cutoff and limit frequencies for PSP coatings.

3、本发明是一种结构简单、加工成本低、使用性强、抗干扰能力强的光学压敏涂料幅频特性检测方法，突破以往采用单像素采集的PMT来获取光学压敏涂料发出的动态荧光光强，本发明基于CCD相机获取较高频率压力下的PSP涂料截止频率和极限频率，实现低帧率CCD相机获得涂料幅频特性的优点。3. The present invention is a method for detecting the amplitude-frequency characteristics of optical pressure-sensitive coatings with simple structure, low processing cost, strong usability and strong anti-interference ability, which breaks through the previous use of single-pixel acquisition PMT to obtain dynamic signals emitted by optical pressure-sensitive coatings. Fluorescent light intensity, the invention obtains the cut-off frequency and limit frequency of the PSP paint under higher frequency pressure based on the CCD camera, and realizes the advantage of the low frame rate CCD camera to obtain the paint amplitude-frequency characteristic.

本领域普通技术人员可以理解，实现上述实施例方法中的全部或部分流程，是可以通过与计算机程序指令相关的硬件来完成的，上述的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，上述的存储介质可为磁碟、光盘、只读存储记忆体(ROM：Read-Only Memory)或随机存储记忆体(RAM：RandomAccess Memory)等。Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above-mentioned embodiments can be implemented by hardware related to computer program instructions, and the above-mentioned programs can be stored in a computer-readable storage medium. When the program is executed, it may include the flow of the embodiments of the above-mentioned methods. The above-mentioned storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM: Read-Only Memory), or a random access memory (RAM: Random Access Memory).

以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视本发明的保护范围。The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (2)

1.一种基于CCD相机的光学压敏涂料幅频特性检测方法，其特征在于，包括以下步骤：1. an optical pressure-sensitive paint amplitude-frequency characteristic detection method based on CCD camera, is characterized in that, comprises the following steps: 步骤1，将PSP样片(2)固定于声学驻波管(1)的底盖位置，在声学驻波管(1)旋紧后，底盖所在平面与声源(11)所在平面平行；信号发生器(8)的第1通道通过功率放大器(9)与声源(11)连接，声源(11)的发声端与声学驻波管(1)连接；Step 1: Fix the PSP sample (2) at the position of the bottom cover of the acoustic standing wave tube (1). After the acoustic standing wave tube (1) is tightened, the plane where the bottom cover is located is parallel to the plane where the sound source (11) is located; the signal The first channel of the generator (8) is connected to the sound source (11) through the power amplifier (9), and the sounding end of the sound source (11) is connected to the acoustic standing wave tube (1); CCD相机(5)和激光光源(3)经声学驻波管(1)的光学视窗(7)对准PSP样片(2)，在CCD相机(5)的镜头前固定安装滤光片(6)；信号发生器(8)的第2通道与CCD相机(5)连接；信号发生器(8)的第3通道与激光光源(3)连接；The CCD camera (5) and the laser light source (3) are aligned with the PSP sample (2) through the optical window (7) of the acoustic standing wave tube (1), and a filter (6) is fixedly installed in front of the lens of the CCD camera (5). ; The second channel of the signal generator (8) is connected with the CCD camera (5); the third channel of the signal generator (8) is connected with the laser light source (3); 在PSP样片(2)所在截面固定动态压力传感器(4)；A dynamic pressure sensor (4) is fixed on the section where the PSP sample (2) is located; 所述CCD相机(5)的输出端和所述动态压力传感器(4)的输出端均连接到计算机(10)；Both the output end of the CCD camera (5) and the output end of the dynamic pressure sensor (4) are connected to a computer (10); 相机、光源经光学视窗对准PSP样片，在PSP样片所在截面固定动态压力传感器用于实时动态压力测量并提供触发信号；The camera and light source are aligned with the PSP sample through the optical window, and a dynamic pressure sensor is fixed on the section where the PSP sample is located for real-time dynamic pressure measurement and providing trigger signals; 步骤2，从t＝0开始，同时启动信号发生器(8)和动态压力传感器(4)；其中，所述动态压力传感器(4)实时测量PSP样片(2)表面所受到的真实压力值，并将PSP样片(2)表面所受到的真实压力值传给所述计算机(10)，由此使所述计算机(10)得到PSP样片(2)表面所受到的真实压力值与时间之间的变化曲线；Step 2, starting from t=0, start the signal generator (8) and the dynamic pressure sensor (4) at the same time; wherein, the dynamic pressure sensor (4) measures the real pressure value on the surface of the PSP sample (2) in real time, and transmit the real pressure value on the surface of the PSP sample (2) to the computer (10), so that the computer (10) obtains the difference between the real pressure value on the surface of the PSP sample (2) and the time. Curve; 所述信号发生器(8)连续输出周期为T1、频率为f1的正弦信号，该正弦信号传递到功率放大器(9)，由功率放大器(9)驱动声源(11)发出周期为T1、频率为f1的正弦声波；The signal generator (8) continuously outputs a sinusoidal signal with a period of T 1 and a frequency of f 1 , the sinusoidal signal is transmitted to the power amplifier (9), and the sound source (11) is driven by the power amplifier (9) to emit a period of T 1 . 1. A sinusoidal sound wave with a frequency of f 1 ; 该正弦声波经声学驻波管(1)作用，从而使PSP样片(2)表面受到稳定的周期为T1、频率为f1的正弦压力驻波；The sinusoidal sound wave is acted on by the acoustic standing wave tube (1), so that the surface of the PSP sample (2) is subjected to a stable sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 ; 步骤3，信号发生器(8)连接激光光源(3)的外触发接口，对激光光源(3)的工作状态进行控制；同时，信号发生器(8)连接CCD相机(5)的外触发接口，对CCD相机(5)的工作状态进行控制；具体控制方式为：Step 3, the signal generator (8) is connected to the external trigger interface of the laser light source (3) to control the working state of the laser light source (3); at the same time, the signal generator (8) is connected to the external trigger interface of the CCD camera (5) , to control the working state of the CCD camera (5); the specific control method is: 步骤3.1，对于周期为T1、频率为f1的正弦压力驻波，将一个正弦压力驻波平均划分为n个相位，依次表示为相位
Figure FDA0003503278790000021
相位
Figure FDA0003503278790000022
…,相位
Figure FDA0003503278790000023
相邻相位之间的时间间隔均为
Figure FDA0003503278790000024
Step 3.1, for a sinusoidal pressure standing wave with a period of T 1 and a frequency of f 1 , divide a sinusoidal pressure standing wave into n phases on average, which are expressed as phases in turn
Figure FDA0003503278790000021
phase
Figure FDA0003503278790000022
..., phase
Figure FDA0003503278790000023
The time interval between adjacent phases is
Figure FDA0003503278790000024
 预设置CCD相机每次的曝光时间te；其中，te≤T1/(n-1)；Preset the exposure time t e of the CCD camera each time; wherein, t e ≤ T 1 /(n-1); 根据CCD相机的帧率，预设置CCD相机的拍摄时间间隔TC＝m×T1+T1/(n-1)；其中，m表示相机拍摄周期间隔的数量；相机的拍摄时间间隔TC大于相机最大帧率的倒数；According to the frame rate of the CCD camera, the shooting time interval T C =m×T 1 +T 1 /(n-1) of the CCD camera is preset; where m represents the number of camera shooting period intervals; the shooting time interval T C of the camera Greater than the inverse of the camera's maximum frame rate; 步骤3.2，在t＝tk时刻，正弦压力驻波为第1个周期中相位
Figure FDA0003503278790000025
的状态；信号发生器(8)同时控制激光光源(3)打开以及CCD相机(5)打开；Step 3.2, at time t = tk, the sinusoidal pressure standing wave is the phase in the first cycle
Figure FDA0003503278790000025
The signal generator (8) simultaneously controls the laser light source (3) to turn on and the CCD camera (5) to turn on; 此时，激光光源(3)打开后，进入长打开模式，即：激光光源(3)打开后，保持稳定功率连续发光照射PSP样片(2)表面，从而激发PSP涂料；At this time, after the laser light source (3) is turned on, it enters the long-on mode, that is, after the laser light source (3) is turned on, the surface of the PSP sample (2) is irradiated with continuous light emission at a stable power, thereby exciting the PSP coating; CCD相机(5)打开后，进行第1次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+te时，关闭CCD相机(5)；此时，CCD相机(5)输出与相位
Figure FDA0003503278790000027
对应的荧光图像Q1；After the CCD camera (5) is turned on, the first exposure is performed, and the exposure time is t e ; when the exposure time is reached, that is: when t=t k +t e , the CCD camera (5) is turned off; at this time, the CCD camera (5) Output and phase
Figure FDA0003503278790000027
the corresponding fluorescence image Q 1 ; 步骤3.3，从相机第1次曝光起始时间开始，即从t＝tk时刻开始算起，经过CCD相机的拍摄时间间隔TC后，即：t＝tk+m×T1+T1/(n-1)时，此时正弦压力驻波为第m+1个周期中相位
Figure FDA0003503278790000026
的状态，此时打开CCD相机(5)，进行第2次曝光，曝光时间为te；当达到曝光时间后，即：当t＝tk+m×T1+T1/(n-1)+te时，关闭CCD相机(5)；此时，CCD相机(5)输出与相位
Figure FDA0003503278790000031
对应的荧光图像Q2；Step 3.3, starting from the start time of the first exposure of the camera, that is, counting from the moment t = tk , after the shooting time interval TC of the CCD camera, namely: t = tk+m × T1 + T1 /(n-1), the sinusoidal pressure standing wave is the phase in the m+1th cycle
Figure FDA0003503278790000026
state, turn on the CCD camera (5) at this time, and perform the second exposure, the exposure time is t e ; when the exposure time is reached, that is: when t=t k +m×T 1 +T 1 /(n-1 )+t e , turn off the CCD camera (5); at this time, the output of the CCD camera (5) and the phase
Figure FDA0003503278790000031
the corresponding fluorescence image Q 2 ; 步骤3.4，从相机第2次曝光起始时间开始，经过CCD相机的拍摄时间间隔TC后，此时正弦压力驻波为第2m+1个周期中相位
Figure FDA0003503278790000032
的状态，打开CCD相机(5)进行第3次曝光，CCD相机(5)输出与相位
Figure FDA0003503278790000033
对应的荧光图像Q3；Step 3.4, starting from the start time of the second exposure of the camera, after the shooting time interval TC of the CCD camera, the sinusoidal pressure standing wave is the phase in the 2m+1 cycle at this time .
Figure FDA0003503278790000032
state, turn on the CCD camera (5) for the third exposure, the output of the CCD camera (5) and the phase
Figure FDA0003503278790000033
the corresponding fluorescence image Q 3 ; 依此类推，在激光光源(3)保持稳定功率连续发光照射PSP样片(2)表面的过程中，每隔CCD相机的拍摄时间间隔TC，CCD相机(5)曝光一次，并输出与正弦压力驻波当前相位对应的荧光图像；直到CCD相机(5)输出与最后一个相位
Figure FDA0003503278790000034
对应的荧光图像Qn；By analogy, in the process that the laser light source (3) maintains a stable power and continuously emits light on the surface of the PSP sample (2), the CCD camera (5) is exposed once every shooting time interval T C of the CCD camera, and the output and the sinusoidal pressure are outputted. The fluorescence image corresponding to the current phase of the standing wave; until the output of the CCD camera (5) is the same as the last phase
Figure FDA0003503278790000034
the corresponding fluorescence image Q n ; 至此，当正弦压力驻波频率为f1时，得到一个完整周期对应的荧光图像序列，分别为：与相位
Figure FDA0003503278790000035
对应的荧光图像Q1，与相位
Figure FDA0003503278790000036
对应的荧光图像Q2,…,与相位
Figure FDA0003503278790000037
对应的荧光图像Qn；So far, when the frequency of the sinusoidal pressure standing wave is f 1 , a sequence of fluorescence images corresponding to a complete cycle is obtained, which are:
Figure FDA0003503278790000035
Corresponding fluorescence image Q 1 , with phase
Figure FDA0003503278790000036
Corresponding fluorescence images Q 2 , . . . , and phase
Figure FDA0003503278790000037
the corresponding fluorescence image Q n ; 步骤4，对于每一个荧光图像Qj，j＝1,2,...,n，均采用以下方式处理：Step 4, for each fluorescence image Q j , j=1, 2, . . . n, are processed in the following manner: 步骤4.1，对荧光图像Qj进行图像处理，得到与相位
Figure FDA0003503278790000038
对应的光强Ij；Step 4.1, perform image processing on the fluorescence image Q j to obtain the phase
Figure FDA0003503278790000038
the corresponding light intensity I j ; 步骤4.2，获取荧光图像Qj获取过程中，CCD相机(5)的曝光时间，再根据CCD相机(5)的曝光时间查找PSP样片(2)表面所受到的真实压力值与时间之间的变化曲线，得到荧光图像Qj对应的真实压力值Pj；Step 4.2, acquiring the fluorescence image Q j During the acquisition process, the exposure time of the CCD camera (5), and then according to the exposure time of the CCD camera (5) to find the change between the real pressure value and the time on the surface of the PSP sample (2) curve to obtain the real pressure value P j corresponding to the fluorescence image Q j ; 步骤4.3，在不向PSP样片(2)施加正弦压力驻波时，即：使PSP样片(2)处于大气压力下，并对PSP样片(2)进行图像拍摄，从而得到参考压力Pref和参考压力下的光强Iref；Step 4.3, when the sine pressure standing wave is not applied to the PSP sample (2), that is: the PSP sample (2) is under atmospheric pressure, and the image of the PSP sample (2) is photographed, thereby obtaining the reference pressure P ref and reference Light intensity I ref under pressure; 步骤5，将光强Ij、真实压力值Pj、参考压力Pref和参考压力下的光强Iref代入以下校准方程(1)：Step 5: Substitute the light intensity I j , the real pressure value P j , the reference pressure P ref and the light intensity I ref under the reference pressure into the following calibration equation (1):
Figure FDA0003503278790000039
Figure FDA0003503278790000039
 由于j＝1,2,...,n，因此，当j＝1时，得到关于A和B的一个方程；当j＝2时，得到关于A和B的一个方程；依此类推，当j＝n时，得到关于A和B的一个方程；因此，共得到n个关于A和B的方程；对n个关于A和B的方程，采用最小二乘法求解，得到最终的A和B的值；Since j=1,2,...,n, when j=1, one equation for A and B is obtained; when j=2, one equation for A and B is obtained; and so on, when When j=n, one equation about A and B is obtained; therefore, a total of n equations about A and B are obtained; for n equations about A and B, the least squares method is used to solve the final equations of A and B. value; A和B均为常数，将A和B的值、参考压力Pref和参考压力下的光强Iref代入校准方程(1)，得到校准方程(2)：Both A and B are constants. Substitute the values of A and B, the reference pressure P ref and the light intensity I ref under the reference pressure into the calibration equation (1) to obtain the calibration equation (2):
Figure FDA0003503278790000041
Figure FDA0003503278790000041
 其中，在校准方程(2)中，Pj'为与光强Ij对应的校准压力值；Wherein, in the calibration equation (2), P j ' is the calibration pressure value corresponding to the light intensity I j ; 步骤6，对于每一个荧光图像Qj，j＝1,2,...,n，均对应相位
Figure FDA0003503278790000042
的值以及光强Ij的值；将光强Ij代入稳态校准后的校准方程(2)，得到对应的校准压力值Pj'；因此，得到相位
Figure FDA0003503278790000043
和校准压力值Pj'的对应关系值；由于j＝1,2,...,n，因此，一共得到n组相位
Figure FDA0003503278790000044
和校准压力值Pj'的对应关系值；由此在横坐标为相位，纵坐标为校准压力值的坐标系中，绘制出n个离散点；将n个离散点拟合形成压力相位曲线；对压力相位曲线进行分析，得到幅值Am(f1)，其含义为：当正弦压力驻波频率为f1时，得到的幅值Am(f1)；Step 6, for each fluorescence image Q j , j=1,2,...,n, all corresponding to the phase
Figure FDA0003503278790000042
and the value of light intensity I j ; substitute light intensity I j into the calibration equation (2) after steady-state calibration to obtain the corresponding calibration pressure value P j '; therefore, the phase
Figure FDA0003503278790000043
and the corresponding relationship value of the calibration pressure value P j '; since j=1,2,...,n, a total of n groups of phases are obtained
Figure FDA0003503278790000044
and the corresponding relationship value of the calibration pressure value P j '; thus, in the coordinate system where the abscissa is the phase and the ordinate is the calibration pressure value, n discrete points are drawn; the n discrete points are fitted to form a pressure phase curve; Analyze the pressure phase curve to obtain the amplitude A m (f 1 ), which means: when the frequency of the sinusoidal pressure standing wave is f 1 , the obtained amplitude A m (f 1 ); 步骤7，保持正弦压力驻波的幅值稳定不变，将正弦压力驻波频率从f1增大到f2，采用步骤2-步骤6的方式，得到对应的幅值Am(f2)；判断幅值Am(f2)是否降低为幅值Am(f1)的一半，如果是，则幅值Am(f2)对应的频率为PSP涂料的截止频率；如果否，则进一步增大正弦压力驻波频率，直到使当前频率fx下的幅值Am(fx)降低为幅值Am(f1)的一半时为止，此时，当前频率fx为PSP涂料的截止频率；Step 7: Keep the amplitude of the sine pressure standing wave stable, increase the frequency of the sine pressure standing wave from f 1 to f 2 , and obtain the corresponding amplitude A m (f 2 ) by adopting the method of step 2 to step 6 ; Judge whether the amplitude A m (f 2 ) is reduced to half of the amplitude A m (f 1 ), if so, the frequency corresponding to the amplitude A m (f 2 ) is the cut-off frequency of the PSP paint; if not, then Further increase the frequency of the sinusoidal pressure standing wave until the amplitude A m (f x ) at the current frequency f x is reduced to half of the amplitude A m (f 1 ), at this time, the current frequency f x is the PSP paint the cut-off frequency; 不断增大正弦压力驻波频率，如果当前频率fz下的幅值Am(fz)降为0，则当前频率fz为PSP涂料的极限频率；由此实现对PSP涂料的幅频特性的检测。Continuously increase the frequency of the sine pressure standing wave, if the amplitude Am ( f z ) under the current frequency f z drops to 0, then the current frequency f z is the limit frequency of the PSP paint; thereby realizing the amplitude-frequency characteristics of the PSP paint detection. 2.根据权利要求1所述的一种基于CCD相机的光学压敏涂料幅频特性检测方法，其特征在于，步骤4.1具体为：2. a kind of optical pressure-sensitive paint amplitude-frequency characteristic detection method based on CCD camera according to claim 1, is characterized in that, step 4.1 is specifically: 荧光图像Qj具有w个像素点；每个像素点均对应一个光强值，因此，共得到w个光强值，对w个光强值求平均值，即为与相位
Figure FDA0003503278790000051
对应的光强Ij。The fluorescence image Q j has w pixels; each pixel corresponds to a light intensity value, therefore, a total of w light intensity values are obtained, and the average value of the w light intensity values is
Figure FDA0003503278790000051
The corresponding light intensity I j .
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