CN103543294B - Micron grating accelerometer testing method based on added mass - Google Patents

Abstract

The invention discloses a method for testing a micron grating accelerometer based on additional mass. Firstly, the parameters of the sensitive head are obtained through theoretical calculation and simulation analysis; Stable platform; then select the quality, quantity and total weight of the additional mass block; place the additional mass block on the stable platform successively, so that the input acceleration value of the accelerometer increases from 0g to the upper limit of the accelerometer measurement range; remove the additional mass block successively in reverse order, The input acceleration value to the accelerometer drops back to 0g; then the average value of the two outputs of the same acceleration input is taken as the corresponding acceleration output; finally, the coefficients of each static mathematical model of the accelerometer are calculated using the least square method, and the test curve is finally drawn . The invention has the advantages of: being beneficial to the improvement of the precision of the optical accelerometer; improving the test environment; and being able to improve the test efficiency of the scale factor of the micron grating accelerometer.

Description

A Test Method of Micron Grating Accelerometer Based on Additional Mass

technical field

The invention relates to the technical field of micron grating accelerometers, and mainly relates to a testing method for micron grating accelerometers based on additional mass.

Background technique

The micron grating accelerometer is a kind of optical inertial device used to measure acceleration and acceleration change. It adopts a mechanical structure formed by semiconductor silicon through micromachining to sense the change of acceleration. The sensitive head structure of the micron grating accelerometer is shown in Figure 1. Shown, including: a central mass 1, a cantilever beam 2, a mirror 3, a micron grating 4 and other structures. The light source (LD outgoing light) is incident on the sensitive head of the micron grating accelerometer. When passing through the micron grating 4, part of the light is reflected by the micron grating 4, and the other part passes through the micron grating 4 and is reflected by the mirror 3 on the lower surface of the central mass 1. Through the micron grating 4; these two parts of light interfere in space to form multi-level fringes; when there is an acceleration input, the central mass 1 is affected by the inertial force, causing the cantilever beam 2 to deform, as shown in Figure 2, so that the reflector 3 and the gap (air cavity) between the micron grating 4 changes, and then the phase of the light beam reflected back from the mirror 3 will change, which will lead to a change in the intensity of the final spatial interference fringes, thus by measuring the intensity of the interference fringes Change to get the magnitude of the input acceleration. The micron grating accelerometer has the advantages of stable performance, high sensitivity, anti-electromagnetic interference, and easy integration. It has broad prospects in aerospace, automotive, seismic monitoring and military systems. However, for the accuracy and range test of the micron grating acceleration, there are problems such as the inability to add controllable and stable acceleration input, and the volume of the measuring device is too large, so it is difficult to realize the accurate test of the micron grating accelerometer.

The high-g precision centrifuge test is mainly used to detect accelerometer parameters such as the scale factor of the accelerometer and the zero bias of the accelerometer when the acceleration input is greater than 1g. Using a high-g precision centrifuge or a stable turntable, the acceleration a is input from the outside to cause the acceleration of the accelerometer. The displacement x of the central mass block, the mass block displacement can change the characteristics of a certain physical quantity in the accelerometer, such as the light intensity I of the grating accelerometer, and the capacitance C of the capacitive accelerometer. The accelerometer is detected by measuring the change in light intensity or the change in capacitance to obtain the magnitude of the acceleration a. However, this test method requires stable centrifuge speed, small structural deformation, small vibration, and accelerometers that can be installed on various radii of the disc that are accurately known. The accuracy of the acceleration it generates depends on the measurement accuracy of the working radius of the centrifuge and the accuracy of the rotational angular velocity of the centrifuge. However, it is difficult to accurately measure the working radius from the rotation axis of the centrifuge to the center of mass of the accelerometer, and the centrifuge is required to have a large size and high rotational stability under high g acceleration, which will lead to further complexity of the structure and test methods, which is not conducive to the acceleration Real-time batch on-line testing is required, resulting in prolonged product development time. The equipment for testing at the same time is expensive, and the test conditions are demanding, which are generally not easy to meet.

Contents of the invention

According to the existing micron grating accelerometer test method, it can be seen that the displacement of the accelerometer center mass is the key to detecting the acceleration, so the present invention is based on the principle of controlling the external environment to change the displacement of the sensitive mass in the accelerometer, and proposes a micron grating A mass block is attached to the central mass block of the accelerometer, and the position of the mass block is changed to provide a micron grating accelerometer test method for external analog acceleration input; it is also applicable to all test methods with cantilever beam accelerometers, specifically through the following steps accomplish:

Step 1: Obtain the detection input acceleration range of the sensitive head of the micron grating accelerometer, the elastic coefficient of the cantilever beam, damping and the mass of the central mass.

Step 2: Install the sensitive head of the micron grating accelerometer on the test table, and set a stable platform on the upper surface of the central mass block of the micron grating accelerometer.

Step 3: Select n additional mass blocks, n is a natural number, and n>1;

The minimum mass M _min of a single additional mass block needs to meet:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1), m _s is the corresponding mass obtained after conversion of the sensitivity of the micron grating accelerometer;

The maximum mass M _max of a single additional mass block needs to meet:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In formula (2), k is a positive integer, k=1, 2, 3...; M _total is the total mass of n additional mass blocks, and the selection range of M _total is:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In formula (3), m _mid is the mass of the central mass of the micron grating accelerometer, g is the acceleration of gravity; a _max is the maximum range of the micron grating accelerometer.

Step 4: Place the additional mass on the stable platform of the micron grating accelerometer, each test starts with the input acceleration value G being 0g, and gradually increase the additional mass on the stable platform to increase the input acceleration value G of the micron grating accelerometer Change until the micron grating accelerometer reaches the upper limit of the measurement range; and record the output acceleration value of the micron grating accelerometer each time the input acceleration value G of the micron grating accelerometer changes incrementally.

Step 5: Remove the additional mass blocks on the stable platform in reverse order of the order of adding additional mass blocks in step 4, so that the input acceleration value G of the micron grating accelerometer changes gradually until the input acceleration value G drops back to 0g; record each time When the input acceleration value G of the micron grating accelerometer changes gradually, the acceleration value output by the micron grating accelerometer.

Step 6: In the process of increasing and decreasing the input acceleration value G, when the input acceleration value G is the same, the output acceleration value of the micron grating accelerometer is averaged to obtain the micron grating accelerometer corresponding to the selected input acceleration value Scaled value for the output acceleration value.

Step 7: According to the calibration value of the output acceleration value of the micron grating accelerometer obtained in step 6, the coefficients of the static mathematical model of the micron grating accelerometer are calculated by least square method.

Step 8: Draw the test curve of the micron grating accelerometer according to the coefficients of the static mathematical model of the micron grating accelerometer.

The advantages of the present invention are:

1. The present invention is based on the micron grating accelerometer test method of additional mass, adopts modular components to replace the traditional detection method, shortens the development time, and has small input noise and strong anti-interference ability, which is conducive to the improvement of the accuracy of the optical accelerometer;

2. The present invention is based on the micron grating accelerometer test method of additional mass, which can realize the test of the micron grating accelerometer scale factor without turntable and centrifuge, and gets rid of the micron grating accelerometer scale factor test to the turntable and centrifuge Dependency improves the test environment;

3. Compared with the traditional scale factor test method, the micron grating accelerometer test method based on the additional mass of the present invention is simple and easy to operate, and can improve the test efficiency of the micron grating accelerometer scale factor.

Description of drawings

Fig. 1 is the structure diagram of micron grating accelerometer;

Fig. 2 is a schematic diagram of the deformation state of the cantilever beam in the micron grating accelerometer;

Fig. 3 is the flow chart of the micron grating accelerometer testing method based on additional quality of the present invention;

4 is a schematic diagram of the installation method of the sensitive head of the micron grating accelerometer and the placement position of the additional mass in the method of testing the micron grating accelerometer based on the additional mass of the present invention.

In the picture:

1-central mass 2-cantilever beam 3-mirror 4-micron grating

Detailed ways

A kind of micron grating accelerometer testing method based on additional mass of the present invention, as shown in Figure 3, specifically realizes by following steps:

Step 1: Through theoretical calculation and simulation analysis, obtain the detectable input acceleration range of the micron grating accelerometer sensitive head, the elastic coefficient of the cantilever beam, the damping and the mass of the central mass and other sensitive head parameters.

Step 2: Install the sensitive head of the micron grating accelerometer on the test table, and install the stable platform on the central mass of the micron grating accelerometer, as shown in Figure 4. In the present invention, guide holes are evenly opened in the circumferential direction of the stabilizing platform, and guide posts are inserted into the guiding holes as guide rails for the stabilizing platform to move up and down, so that the stabilizing platform only has displacement in the up and down direction.

Step 3: Select n additional mass blocks, where n is a natural number and n>1.

Among them, the minimum mass M _min of a single additional mass block (unit: gram) needs to meet:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1), m _s is the corresponding mass obtained after conversion of the sensitivity of the micron grating accelerometer;

The maximum mass M _max (unit: gram) of a single additional mass must meet:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In formula (2), k is a positive integer, k=1, 2, 3...; M _total is the total mass of n additional mass blocks, and the selection range of M _total can be obtained according to the range of the micron grating accelerometer:

$\left\{\begin{array}{c}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; x</span>}\\ {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; x</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In formula (3), m _mid is the mass of the central mass of the micron grating accelerometer, g is the gravitational acceleration, q is the elastic coefficient of the cantilever beam of the micron grating accelerometer; a is the acceleration, a selects the maximum range of the micron grating accelerometer, that is, a _max ; thus according to formula (3), it can be obtained:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The selection of the number n of the mass blocks should meet the requirements of the accelerometer performance test, that is, under the condition that the sensitivity and range range of the micron grating accelerometer can be accurately tested, a smaller number should be selected as much as possible;

Step 4: Place the additional mass on the stable platform of the micron grating accelerometer. Each test starts with the input acceleration value G being 0g (that is, no additional mass), and gradually increases the additional mass on the stable platform; thus the acceleration of the micron grating The input acceleration value G of the meter changes incrementally until the micron grating accelerometer reaches the upper limit of the measurement range (for the micron grating accelerometer, the upper limit of the measurement range refers to the limit of the gap change between the mass block and the grating surface in the design index) ; and record the acceleration value output by the micron grating accelerometer each time the input acceleration value of the micron grating accelerometer changes incrementally.

In the above-mentioned micron grating accelerometer test, the input acceleration value G of the micron grating accelerometer changes incrementally according to: G ₀ =0, G ₁ =M _min , G ₂ =2M _min , G ₃ =4M _min ,...,G _p =M _max ; and 2G ₁ +G ₂ +G ₃ +...+G _p ≈M _total ; wherein, the subscripts 1, 2, 3,..., p of the acceleration value G are the number of incremental changes;

Step 5: Remove the additional mass blocks on the stable platform in reverse order of the order of adding additional mass blocks in step 4, so that the input acceleration value G of the micron grating accelerometer changes gradually until the input acceleration value G drops back to 0g; record each time When the input acceleration G value of the micron grating accelerometer changes gradually, the acceleration value output by the micron grating accelerometer.

Step 6: Due to the recovery problem of the cantilever beam of the accelerometer, when the input acceleration value G is changed in increasing and decreasing order, different actual test output acceleration values will be obtained under the condition that the input acceleration values G are equal; thus In the process of increasing and decreasing the input acceleration value G, when the same input acceleration value G is selected, the output acceleration value of the micron grating accelerometer is averaged to obtain the output acceleration of the micron grating accelerometer corresponding to the selected input acceleration value G The scaled value of the value.

Step 7: According to the calibration value of the output acceleration value of the micron grating accelerometer obtained in step 6, calculate the coefficients of the static mathematical model of the micron grating accelerometer through the least square method, including the threshold value, resolution, and scale of the micron grating accelerometer Factors and non-linearity and other parameters.

Step 8: Draw the test curve of the micron grating accelerometer according to the coefficients of the static mathematical model of the micron grating accelerometer.

The quality of the stable platform of the micron grating accelerometer in the present invention is selected according to the theoretical simulation results and the sensitivity requirements of the sensitive head of the micron grating accelerometer. Under the condition of ensuring the working point of the accelerometer, the mass accuracy of the stable platform is selected as ±M _min . The mass of the stable table is negligible in the test method of the present invention.

Claims (3)

1. a kind of micron grating accelerometer test method based on additional quality, it is characterized in that: specifically realize by following steps: Step 1: Obtain the detection input acceleration range of the sensitive head of the micron grating accelerometer, the elastic coefficient of the cantilever beam, damping and the mass of the central mass; Step 2: Install the sensitive head of the micron grating accelerometer on the test table, and set a stable platform on the upper surface of the central mass of the micron grating accelerometer; Step 3: Select n additional mass blocks, n is a natural number, and n>1; The minimum mass M _min of a single additional mass block needs to meet: ${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ In formula (1), m _s is the corresponding mass obtained after conversion of the sensitivity of the micron grating accelerometer; The maximum mass M _max of a single additional mass block needs to meet: ${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ In formula (2), k is a positive integer, k=1, 2, 3...; M _total is the total mass of n additional mass blocks, and the selection range of M _total is: ${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; middle</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ In formula (3), m _mid is the mass of the central mass of the micron grating accelerometer, g is the acceleration of gravity; a _max is the maximum range of the micron grating accelerometer; Step 4: Place the additional mass on the stable platform, and each test starts with the input acceleration value G being 0g, and gradually increase the additional mass on the stable platform, so that the input acceleration value G of the micron grating accelerometer changes incrementally until micron The grating accelerometer reaches the upper limit of the measurement range; and records the acceleration value output by the micron grating accelerometer each time the input acceleration value G of the micron grating accelerometer changes incrementally; Step 5: Remove the additional mass blocks on the stable platform in reverse order of the order of adding additional mass blocks in step 4, so that the input acceleration value G of the micron grating accelerometer changes gradually until the input acceleration value G drops back to 0g; record each time When the input acceleration value G of the micron grating accelerometer changes gradually, the acceleration value output by the micron grating accelerometer; Step 6: In the process of increasing and decreasing the input acceleration value G, when the input acceleration value G is the same, the output acceleration value of the micron grating accelerometer is averaged to obtain the micron grating accelerometer corresponding to the selected input acceleration value Output the calibration value of the acceleration value; Step 7: Calculate the coefficient of the static mathematical model of the micron grating accelerometer according to the calibration value of the micron grating accelerometer output acceleration value obtained in step 6, by the least square method; Step 8: Draw the test curve of the micron grating accelerometer according to the coefficients of the static mathematical model of the micron grating accelerometer. 2. a kind of micron grating accelerometer test method based on additional mass as claimed in claim 1, is characterized in that: micron grating accelerometer input acceleration value G increments according to: G ₀ corresponding quality is 0, G ₁ corresponding quality is M _{min ,} G ₂ corresponds to a mass _of 2M _min , G ₃ corresponds _to a mass of 4M _min , ..., _{G p} corresponds to a mass of M _max ; and are approximately equal to the sum of the masses of all additional mass blocks; wherein, the subscripts 1, 2, 3, ..., p of the acceleration value G are the number of incremental changes. 3. a kind of micron grating accelerometer test method based on additional mass as claimed in claim 1, is characterized in that: the circumferential direction of described stable platform evenly has guide hole, by inserting guide post in guide hole, as stable platform The guide rail that moves up and down makes the stable table only have displacement in the up and down direction.