CN104237561A

CN104237561A - Spatial acceleration measuring method and device based on fiber grating curvature sensing network

Info

Publication number: CN104237561A
Application number: CN201310455295.7A
Authority: CN
Inventors: 张伦伟; 杨国标; 曾伟明; 王璟渝
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2013-09-29
Filing date: 2013-09-29
Publication date: 2014-12-24

Abstract

The invention relates to a space acceleration measurement technology based on a fiber grating curvature sensing network. A flexible space coordinate detection rod is attached to a mechanical component to be tested. When the mechanical component moves, the fiber grating on the flexible space coordinate detection rod measures strain information , through the fiber grating demodulator to demodulate into digital wavelength information and input it into the computer, the computer first converts the digital wavelength information into curvature information, and deduces the spatial coordinate information from the curvature information, and then calculates the acceleration through numerical difference, and finally Display the acceleration in real time. Compared with the prior art, the invention has the advantages of high measurement precision, good real-time performance, wide application range and the like.

Description

Method and device for measuring spatial acceleration based on fiber grating curvature sensing network

技术领域technical field

本发明涉及一种空间加速度测量技术，尤其是涉及一种基于光纤光栅曲率感知网络的空间加速度测量方法和装置。The invention relates to a space acceleration measurement technology, in particular to a space acceleration measurement method and device based on a fiber grating curvature sensing network.

背景技术Background technique

空间加速度的测量对工程机械的精确有效控制有十分重要的意义，但目前还没有基于曲率测量的能实现全场空间加速度实时测量的系统。现有的基于光纤光栅的加速度传感器只能实现单点测量，其设计思路主要是设计带有质量块的传感头，质量块在振动时产生惯性力，在惯性力作用下传感头结构会产生相应的应变，通过光纤光栅等敏感元件测量出相应应变，再通过结构的应力应变关系就可以求出惯性力，进而求得加速度。The measurement of spatial acceleration is of great significance to the precise and effective control of construction machinery, but there is no system based on curvature measurement that can realize real-time measurement of full-field spatial acceleration. Existing fiber grating-based acceleration sensors can only achieve single-point measurement. The design idea is to design a sensor head with a mass block. The mass block generates inertial force when it vibrates. Under the action of inertial force, the structure of the sensor head The corresponding strain is generated, and the corresponding strain is measured by sensitive elements such as fiber gratings, and then the inertial force can be obtained through the stress-strain relationship of the structure, and then the acceleration can be obtained.

发明内容Contents of the invention

本发明的目的就是为了克服上述现有技术存在的缺陷而提供一种基于光纤光栅曲率感知网络的空间加速度测量方法和装置。The object of the present invention is to provide a method and device for measuring spatial acceleration based on a fiber grating curvature sensing network in order to overcome the above-mentioned defects in the prior art.

本发明的目的可以通过以下技术方案来实现：The purpose of the present invention can be achieved through the following technical solutions:

一种基于光纤光栅曲率感知网络的空间加速度测量方法，包括以下步骤：A method for measuring spatial acceleration based on a fiber grating curvature sensing network, comprising the following steps:

1)通过圆弧样条曲线标定处理，确定柔性空间坐标检测杆上各个检测点的应变信号与柔性空间坐标检测杆的曲线曲率间的比例系数K；1) Through arc spline curve calibration processing, determine the proportional coefficient K between the strain signal of each detection point on the flexible space coordinate detection rod and the curve curvature of the flexible space coordinate detection rod;

2)将柔性空间坐标检测杆紧贴于待检测的机械构件上，由各个检测点的光纤光栅根据柔性空间坐标检测杆的弯曲度，获取应变信号：2) The flexible spatial coordinate detection rod is attached to the mechanical component to be detected, and the fiber grating at each detection point is used to obtain the strain signal according to the bending degree of the flexible spatial coordinate detection rod:

3)各个检测点的应变信号经对应的光纤光栅解调仪器转换成数字波长信号，由计算机实时采集：3) The strain signal of each detection point is converted into a digital wavelength signal by the corresponding fiber grating demodulation instrument, which is collected by the computer in real time:

4)计算机根据实时采集的数字波长信号信号，进行圆弧样条曲线标定处理，得到波长信号变化值和柔性空间坐标检测杆曲率值之间的对应关系，并根据此关系计算出柔性空间坐标检测杆上各个检测点处的曲率；4) According to the real-time collected digital wavelength signal signal, the computer performs arc spline curve calibration processing, obtains the corresponding relationship between the wavelength signal change value and the curvature value of the flexible space coordinate detection rod, and calculates the flexible space coordinate detection according to this relationship. Curvature at each detection point on the rod;

5)计算机根据柔性空间坐标检测杆上多个检测点的曲率信息，递推出柔性空间坐标检测杆上各检测点的空间坐标信息；5) The computer deduces the space coordinate information of each detection point on the flexible space coordinate detection rod according to the curvature information of multiple detection points on the flexible space coordinate detection rod;

6)计算机处理由柔性空间坐标检测杆的空间坐标信息，将空间坐标信息中X、Y、Z三个方向的坐标对时间进行向后二次数值差分计算，得到X、Y、Z三个方向的加速度。6) The computer processes the space coordinate information of the flexible space coordinate detection rod, and calculates the coordinates in the three directions of X, Y, and Z in the space coordinate information with respect to time, and performs backward quadratic numerical difference calculation to obtain the three directions of X, Y, and Z. acceleration.

步骤1)中的圆弧样条曲线标定处理具体过程为：对于每个检测点的光纤光栅，先测出柔性空间坐标检测杆在若干个已知曲率半径ρ下的光纤光栅的中心波长λ，根据公式K=λ×ρ求出每个曲率半径ρ下的比例系数，然后取其平均值作为下一测量点的光纤光栅的比例系数K。The specific process of arc spline curve calibration in step 1) is: for the fiber grating at each detection point, first measure the central wavelength λ of the fiber grating of the flexible space coordinate detection rod under several known curvature radii ρ, According to the formula K=λ×ρ, the proportional coefficient under each curvature radius ρ is obtained, and then the average value is taken as the proportional coefficient K of the fiber grating at the next measurement point.

步骤6)中采用向后二次数值差分计算后，则有第i点t时刻的加速度为：After step 6) adopts the backward quadratic numerical difference calculation, the acceleration of the i-th point at time t is:

$\{\begin{matrix} {A A}_{itx itx} = = \frac{{X x}_{i i} ((t t)) - - 22 \cdot \cdot {X x}_{i i} ((t t - - Δt Δt)) + + {X x}_{i i} ((t t - - 22 \cdot \cdot Δt Δt))}{{((Δt Δt))}^{22}} \\ {A A}_{ity the city} = = \frac{{Y Y}_{i i} ((t t)) - - 22 \cdot \cdot {Y Y}_{i i} ((t t - - Δt Δt)) + + {Y Y}_{i i} ((t t - - 22 \cdot \cdot Δt Δt))}{{((Δt Δt))}^{22}} \\ {A A}_{itz itz} = = \frac{{Z Z}_{i i} ((t t)) - - 22 \cdot \cdot {Z Z}_{i i} ((t t - - Δt Δt)) + + {Z Z}_{i i} ((t t - - 22 \cdot \cdot Δt Δt))}{{((Δt Δt))}^{22}} \end{matrix}\}$

式中，Aitx、Aity、Aitz分别为第i点t时刻在空间笛卡尔坐标系中x、y、z方向的加速度，Xi(t)、Yi(t)、Zi(t)分别为第i点t时刻在空间笛卡尔坐标系中x、y、z轴的坐标。In the formula, Aitx, Aity, and Aitz are the accelerations in the x, y, and z directions of the i-th point in the spatial Cartesian coordinate system at time t, respectively, and Xi(t), Yi(t), and Zi(t) are the i-th point The coordinates of the x, y, and z axes in the spatial Cartesian coordinate system at time t.

一种基于光纤光栅曲率感知网络的空间加速度测量装置，包括：A space acceleration measurement device based on a fiber grating curvature sensing network, comprising:

柔性空间坐标检测杆：依附于待检测的机械构件，并紧贴该机械构件的外壁，柔性空间坐标检测杆内部沿轴向设有多个检测点，每个检测点设置光纤光栅用于获取应变信号；Flexible spatial coordinate detection rod: attached to the mechanical component to be detected, and close to the outer wall of the mechanical component, the flexible spatial coordinate detection rod is equipped with multiple detection points along the axial direction, and each detection point is equipped with a fiber grating to obtain the strain Signal;

光纤光栅解调仪：由检测点获取应变信号，将多个离散的检测点的应变信号转换成数字波长信号；Fiber Bragg grating demodulator: Obtain strain signals from detection points, and convert the strain signals of multiple discrete detection points into digital wavelength signals;

计算机：由光纤光栅解调仪获取数字波长信号，获得每个检测点处的加速度。Computer: The digital wavelength signal is obtained by the fiber grating demodulator, and the acceleration at each detection point is obtained.

多个检测点沿柔性空间坐标检测杆轴向均匀布置，每个检测点均包含分别两组的4根光纤光栅，4根光纤光栅沿沿柔性空间坐标检测杆的圆形横截面均匀分布。与现有技术相比，本发明具有以下优点：Multiple detection points are evenly arranged along the axis of the flexible space coordinate detection rod, and each detection point includes two groups of 4 fiber gratings, and the 4 fiber gratings are evenly distributed along the circular cross section of the flexible space coordinate detection rod. Compared with the prior art, the present invention has the following advantages:

1.由于整个加速度测量系统主要由光纤光栅传感网络、光纤光栅解调仪器和计算机组成，不需要额外的辅助设备，所以整个系统的组成简单，不易受电磁波等外界因素的影响。1. Since the entire acceleration measurement system is mainly composed of a fiber grating sensor network, a fiber grating demodulation instrument and a computer, no additional auxiliary equipment is required, so the entire system is simple in composition and is not easily affected by external factors such as electromagnetic waves.

2.由于本空间加速度测量系统是在柔性空间坐标检测杆上布置多个曲率检测光纤光栅，对多点的曲率检测是以并行方式同时进行的，因此整个空间加速度测量系统可以实现全场实时测量，这种测量技术适用于多刚体机械臂以及柔性细长机械构件的加速度测量，并且能够达到很高的实时响应性。2. Since the space acceleration measurement system arranges multiple curvature detection fiber gratings on the flexible space coordinate detection rod, the curvature detection of multiple points is carried out in parallel, so the entire space acceleration measurement system can realize real-time measurement of the whole field , this measurement technique is suitable for the acceleration measurement of multi-rigid manipulators and flexible and slender mechanical components, and can achieve high real-time responsiveness.

3.光纤光栅传感方式具有尺寸小，测量范围大的优点，可以根据工程机械的要求设计出合适的柔性空间坐标检测杆来进行测量。3. The fiber grating sensing method has the advantages of small size and large measurement range, and a suitable flexible space coordinate detection rod can be designed according to the requirements of construction machinery for measurement.

4.本发明基于光纤光栅的空间加速度测量系统组成简单，测量方法简便，非专业人员也可以很快熟悉操作方法。4. The optical fiber grating-based spatial acceleration measurement system of the present invention has simple composition and simple measurement method, and non-professionals can quickly become familiar with the operation method.

附图说明Description of drawings

图1为本发明的结构示意图；Fig. 1 is a structural representation of the present invention;

图2柔性空间坐标检测杆的光纤光栅传感器布置示意图；Fig. 2 is a schematic diagram of the layout of the fiber grating sensor of the flexible spatial coordinate detection rod;

图3为柔性空间坐标检测杆的局部放大图；Fig. 3 is a partial enlarged view of the flexible space coordinate detection rod;

图4为基于离散点曲率信息的重建原理图；Figure 4 is a schematic diagram of reconstruction based on discrete point curvature information;

图5-图7为递推柔性空间坐标检测杆上各检测点的空间坐标信息的的分解图；Fig. 5-Fig. 7 is the exploded view of the space coordinate information of each detection point on the recursive flexible space coordinate detection rod;

图中，1为计算机、2为光纤光栅解调仪、3为柔性空间坐标检测杆、4为待测的机械构件、5为每个检测点上的光纤光栅。In the figure, 1 is a computer, 2 is an optical fiber grating demodulator, 3 is a flexible spatial coordinate detection rod, 4 is a mechanical component to be tested, and 5 is an optical fiber grating on each detection point.

具体实施方式Detailed ways

下面结合附图和具体实施例对本发明进行详细说明。The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

实施例Example

本发明提供了一种基于光纤光栅曲率感知网络的空间加速度测量方法，该方法包括以下步骤：The invention provides a method for measuring spatial acceleration based on a fiber grating curvature sensing network, the method comprising the following steps:

步骤一，通过圆弧样条曲线标定处理，确定柔性空间坐标检测杆上各个检测点的应变信号与柔性空间坐标检测杆的曲线曲率间的比例系数K。其中，圆弧样条曲线标定处理具体过程为：对于每个检测点的光纤光栅，先测出柔性空间坐标检测杆在若干个已知曲率半径ρ下的光纤光栅的中心波长λ，根据公式K=λ×ρ求出每个曲率半径ρ下的比例系数，然后取其平均值作为下一测量点的光纤光栅的比例系数K。Step 1, through arc spline calibration processing, determine the proportional coefficient K between the strain signal of each detection point on the flexible space coordinate detection rod and the curvature of the curve of the flexible space coordinate detection rod. Among them, the specific process of arc spline curve calibration process is as follows: for the fiber grating at each detection point, first measure the central wavelength λ of the fiber grating of the flexible space coordinate detection rod under several known curvature radii ρ, according to the formula K =λ×ρ Calculate the proportional coefficient under each curvature radius ρ, and then take its average value as the proportional coefficient K of the fiber grating at the next measurement point.

步骤二，将柔性空间坐标检测杆紧贴于待检测的机械构件上，由各个检测点的光纤光栅根据柔性空间坐标检测杆的弯曲度，获取应变信号。Step 2, the flexible spatial coordinate detection rod is attached to the mechanical component to be detected, and the fiber gratings at each detection point are used to obtain strain signals according to the bending degree of the flexible spatial coordinate detection rod.

步骤三，各个检测点的应变信号经对应的光纤光栅解调仪器转换成数字波长信号，由计算机实时采集。Step 3: The strain signal of each detection point is converted into a digital wavelength signal by a corresponding fiber grating demodulation instrument, and is collected by a computer in real time.

步骤四，计算机根据实时采集的数字波长信号信号，进行圆弧样条曲线标定处理，得到波长信号变化值和柔性空间坐标检测杆曲率值之间的对应关系，并根据此关系计算出柔性空间坐标检测杆上各个检测点处的曲率。Step 4: The computer performs arc spline calibration processing according to the digital wavelength signal signal collected in real time, and obtains the corresponding relationship between the change value of the wavelength signal and the curvature value of the flexible space coordinate detection rod, and calculates the flexible space coordinate according to this relationship. Detect the curvature at each detection point on the rod.

步骤五，计算机根据柔性空间坐标检测杆上多个检测点的曲率信息，递推出柔性空间坐标检测杆上各检测点的空间坐标信息。该步骤中，具体递推方法如下，结合图4对其进行具体说明：Step five, the computer deduces the space coordinate information of each detection point on the flexible space coordinate detection rod according to the curvature information of multiple detection points on the flexible space coordinate detection rod. In this step, the specific recursive method is as follows, which will be described in detail in conjunction with Figure 4:

1、在坐标系{B_i}中对进行两个曲率分量进行矢量合成，合成的曲率矢量k_i，大小为：1. Carry out vector synthesis of two curvature components in the coordinate system {B _i }, and the size of the synthesized curvature vector k _i is:

$| | {k k}_{i i} | | = = \sqrt{{k k}_{ai ai}^{22} + + {k k}_{bi bi}^{22}}$

如图5所示，虚线所在表示的平面为点i的密切平面，图中κ_i为两个正交平面曲率矢量合成的点i的空间曲率，其方向即为点i的法线方向。As shown in Figure 5, the plane indicated by the dotted line is the close plane of point i. In the figure, κ _i is the spatial curvature of point i synthesized by two orthogonal plane curvature vectors, and its direction is the normal direction of point i.

k_i与k_ai的夹角α_i为：The angle α _i between k _i and k _ai is:

${α α}_{i i} = = \{\begin{matrix} {tan the tan}^{- - 11} (({k k}_{bi bi} / / {k k}_{ai ai})) + + π π (({k k}_{ai ai} < < 00)) \\ - - π π / / 22 (({k k}_{ai ai} = = 00,, {k k}_{bi bi} < < 00)) \\ 00 (({k k}_{ai ai} = = 00,, {k k}_{bi bi} = = 00)) \\ π π / / 22 (({k k}_{ai ai} = = 00,, {k k}_{bi bi} > > 00)) \\ {tan the tan}^{- - 11} (({k k}_{bi bi} / / {k k}_{ai ai})) (({k k}_{ai ai} > > 00)) \end{matrix}$

具体如图6所示。Specifically shown in Figure 6.

2、采用线性插值从离散曲率获得连续曲率；2. Use linear interpolation to obtain continuous curvature from discrete curvature;

3、建立一下检测点的的坐标系{B_i+1}；3. Establish the coordinate system {B _i+1 } of the detection point;

4、在运动坐标系{B_i+1}中递推坐标：4. Recursive coordinates in the motion coordinate system {B _i+1 }:

运动坐标系中坐标递推图解图中中所示的几何关系就可以在点i的运动坐标系中计算点i+1相对于点i的坐标增量(dx_i，dy_i，dz_i)，(dx_i，dy_i，dz_i)可以根据κ_i矢量的大小是否为零。因为运动坐标系是以点i为原点的，所以点i在点i的运动坐标系中的坐标为(0，0，0)，因此根据上面的结论，点i+1在点i的运动坐标系中的坐标为(0+dx_i，0+dy_i，0+dz_i)=(dx_i，dy_i，dz_i)。因为要满足点i+1与点i之间的弧段在一个平面内且为圆弧就必须满足点i+1与点i之间的曲线段十分微小，所以每一个运动坐标系只确定相邻下一点的坐标。即点i的运动坐标系只确定点i+1的坐标，点i+1的运动坐标系只确定点i+2的坐标，以此类推就可以递推计算出曲线上各点在空间笛卡尔坐标系中的坐标。The geometric relationship shown in the diagram of coordinate recursion in the motion coordinate system can calculate the coordinate increment (dx _i , dy _i , dz _i ) of point i+1 relative to point i in the motion coordinate system of point i, (dx _i , dy _i , dz _i ) can be determined according to whether the magnitude of the κ _i vector is zero. Because the motion coordinate system is based on point i, the coordinates of point i in the motion coordinate system of point i are (0, 0, 0), so according to the above conclusion, the motion coordinates of point i+1 at point i The coordinates in the system are (0+dx _i , 0+dy _i , 0+dz _i )=(dx _i , dy _i , dz _i ). Because the arc segment between point i+1 and point i must be satisfied that the arc segment between point i+1 and point i is in a plane and is a circular arc, the curve segment between point i+1 and point i must be very small, so each motion coordinate system only determines the phase The coordinates of the next point. That is, the motion coordinate system of point i only determines the coordinates of point i+1, and the motion coordinate system of point i+1 only determines the coordinates of point i+2. By analogy, the spatial Cartesian space of each point on the curve can be recursively calculated. Coordinates in the coordinate system.

5、坐标系{B_i+1}转换至笛卡尔坐标，如图7所示；5. Convert the coordinate system {B _i+1 } to Cartesian coordinates, as shown in Figure 7;

[I+1]=[D_i][I]运动坐标系就从i点的运动坐标系变换为i+1点的运动坐标系，[D_i]是齐次坐标系转换矩阵。[I+1]=[D _i ][I] The motion coordinate system is transformed from the motion coordinate system of point i to the motion coordinate system of point i+1, and [D _i ] is the homogeneous coordinate system conversion matrix.

$\{\begin{matrix} {x x}_{i i + + 11} \\ {y the y}_{i i + + 11} \\ {z z}_{i i + + 11} \\ 11 \end{matrix}\} = = {[[DI DI]]}^{- - 11} \{\begin{matrix} {dx dx}_{i i} \\ {dy dy}_{i i} \\ {dz dz}_{i i} \\ 11 \end{matrix}\}$

上式即实现了基材变形后中心线上各点坐标在空间笛卡尔坐标系中的递推。The above formula realizes the recursion of the coordinates of each point on the center line in the spatial Cartesian coordinate system after the substrate is deformed.

步骤六，计算机处理由柔性空间坐标检测杆的空间坐标信息，将空间坐标信息中X、Y、Z三个方向的坐标对时间进行向后二次数值差分计算，得到第i点t时刻的加速度：Step 6, the computer processes the space coordinate information of the flexible space coordinate detection rod, and calculates the coordinates in the three directions of X, Y, and Z in the space coordinate information with respect to time, and calculates the backward quadratic numerical difference to obtain the acceleration of the i-th point at time t :

由此可以获取X、Y、Z三个方向的加速度。In this way, the acceleration in the X, Y, and Z directions can be obtained.

上述方法可以采用如图1～3所示测量装置实现，该装置包括柔性空间坐标检测杆3、光纤光栅解调仪2、计算机3。其中，柔性空间坐标检测杆3依附于待检测的机械构件，并紧贴该机械构件的外壁，柔性空间坐标检测杆内部沿轴向设有多个检测点，每个检测点设置光纤光栅用于获取应变信号。这些检测点沿柔性空间坐标检测杆轴向均匀布置，每个检测点均包含分别两组的4根光纤光栅，4根光纤光栅沿沿柔性空间坐标检测杆的圆形横截面均匀分布，相互之间呈90°。光纤光栅解调仪用于从检测点获取应变信号，将多个离散的检测点的应变信号转换成数字波长信号。计算机用于获取光纤光栅解调仪获取数字波长信号，最终得到每个检测点处的加速度。The above method can be realized by using the measuring device as shown in FIGS. Among them, the flexible spatial coordinate detection rod 3 is attached to the mechanical component to be detected, and is close to the outer wall of the mechanical component. A plurality of detection points are arranged inside the flexible spatial coordinate detection rod along the axial direction, and each detection point is provided with a fiber grating for Get the strain signal. These detection points are evenly arranged along the axis of the flexible space coordinate detection rod, and each detection point contains four fiber gratings in two groups, and the four fiber gratings are evenly distributed along the circular cross section of the flexible space coordinate detection rod. between 90°. The fiber grating demodulator is used to obtain strain signals from detection points, and convert the strain signals of multiple discrete detection points into digital wavelength signals. The computer is used to obtain the fiber grating demodulator to obtain the digital wavelength signal, and finally obtain the acceleration at each detection point.

Claims

1., based on a steric acceleration measuring method for fiber bragg grating curvature sensing network, it is characterized in that, comprise the following steps:

1) demarcate process by arc-spline curve, determine the Proportional coefficient K between the strain signal of each check point on flexible space coordinate measurement bar and the curvature of curve of flexible space coordinate measurement bar;

2) flexible space coordinate measurement bar is close on mechanical component to be detected, by the fiber grating of each check point according to the flexibility of flexible space coordinate measurement bar, obtains strain signal;

3) strain signal of each check point converts digital wavelength signal to, by computer real-time acquisition through the fiber Bragg grating (FBG) demodulator device of correspondence;

4) computing machine is according to the digital wavelength signal of Real-time Collection, carry out arc-spline curve and demarcate process, obtain the corresponding relation between wavelength signals changing value and flexible space coordinate measurement bar curvature value, and calculate the curvature at each check point place on flexible space coordinate measurement bar according to this relation;

5) computing machine is according to the curvature information of multiple check point on flexible space coordinate measurement bar, and recursion goes out the spatial coordinated information of each check point on flexible space coordinate measurement bar;

6) computer disposal is by the spatial coordinated information of flexible space coordinate measurement bar, the coordinate in tri-directions of X, Y, Z in spatial coordinated information is carried out secondary diff backward to the time and calculates, obtain the acceleration in X, Y, Z tri-directions.

2. a kind of steric acceleration measuring method based on fiber bragg grating curvature sensing network according to claim 1, it is characterized in that, step 1) in arc-spline curve demarcate process detailed process be: for the fiber grating of each check point, first measure the central wavelength lambda of the fiber grating of flexible space coordinate measurement bar under several known curvature radiuses ρ, obtain the scale-up factor under each radius-of-curvature ρ according to formula K=λ × ρ, then get the Proportional coefficient K of its mean value as the fiber grating of next measurement point.

3. a kind of steric acceleration measuring method based on fiber bragg grating curvature sensing network according to claim 1, step 6) in adopt after secondary diff calculates backward, then have the acceleration of i-th t to be:

\{\begin{matrix} A_{itx} = \frac{X_{i} (t) - 2 \cdot X_{i} (t - Δt) + X_{i} (t - 2 \cdot Δt)}{{(Δt)}^{2}} \\ A_{ity} = \frac{Y_{i} (t) - 2 \cdot Y_{i} (t - Δt) + Y_{i} (t - 2 \cdot Δt)}{{(Δt)}^{2}} \\ A_{itz} = \frac{Z_{i} (t) - 2 \cdot Z_{i} (t - Δt) + Z_{i} (t - 2 \cdot Δt)}{{(Δt)}^{2}} \end{matrix}\}

In formula, Aitx, Aity, Aitz are respectively the acceleration in i-th t x, y, z direction in dimensional Cartesian coordinates system, and Xi (t), Yi (t), Zi (t) are respectively the coordinate of i-th t x, y, z axle in dimensional Cartesian coordinates system.

4., based on a steric acceleration measurement mechanism for fiber bragg grating curvature sensing network, it is characterized in that, comprising:

Flexible space coordinate measurement bar: depend on mechanical component to be detected, and be close to the outer wall of this mechanical component, flexible space coordinate measurement bar inside is provided with multiple check point vertically, and each check point arranges fiber grating for obtaining strain signal;

Fiber Bragg grating (FBG) demodulator: obtain strain signal by check point, converts the strain signal of multiple discrete check point to digital wavelength signal;

Computing machine: obtain digital wavelength signals by fiber Bragg grating (FBG) demodulator, obtains the acceleration at each check point place.

5. a kind of steric acceleration measurement mechanism based on fiber bragg grating curvature sensing network according to claim 4, it is characterized in that, multiple check point is axially evenly arranged along flexible space coordinate measurement bar, each check point all comprises 4 fiber gratings of two groups respectively, and 4 fiber gratings are uniformly distributed along the circular cross section along flexible space coordinate measurement bar.