CN116953288A - Accelerometer resolution testing device and method utilizing excitation force of double eccentric motors - Google Patents
Accelerometer resolution testing device and method utilizing excitation force of double eccentric motors Download PDFInfo
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Abstract
The invention discloses an accelerometer resolution testing device and method utilizing exciting force of a double eccentric motor. The stepping motor and the accelerometer are arranged on the optical platform, the rotating shaft of the stepping motor is connected with two eccentric blocks, the accelerometer is connected with the terminal computer through a signal acquisition system, and the two eccentric blocks are symmetrically distributed; the method comprises the steps of giving a target acceleration variation, selecting a plurality of groups of target included angles and target included angle increments according to the same target acceleration variation, obtaining an average value of accelerometer output signal amplitude differences corresponding to the plurality of groups of target included angles and the target included angle increments, comparing the average value with the target acceleration variation, judging whether the given target acceleration variation meets the standard, and selecting the minimum value in the standard target acceleration variation as the accelerometer resolution. The invention is tested on the optical platform, has simple structure device and low cost, can realize extremely high resolution without the help of a precise rotating device, and has strong practicability.
Description
Technical Field
The invention belongs to an accelerometer resolution testing device and method in the field of accelerometer sensors, and particularly relates to an accelerometer resolution testing device and method utilizing exciting force of a double eccentric motor.
Background
The accelerometer is an instrument for measuring the linear acceleration of a carrier, consists of a detection mass (also called a sensitive mass), a support, a potentiometer, a spring, a damper and a shell, has the characteristics of simple structure and high precision, and has wide application in an inertial navigation system and a geodetic system. Resolution is an important indicator of an accelerometer, reflects the minimum limit of acceleration that the accelerometer can measure, and the higher the resolution, the more sensitive the accelerometer is to weak acceleration, and resolution measurement is of great importance in calibration and application of high-precision accelerometers.
When the accelerometer resolution test is carried out, a tiny acceleration input is needed to be manually given to the accelerometer, then signal output sampling and data processing are carried out, and in order to realize the measurement of the high-resolution accelerometer, the test method is at least one order of magnitude higher than the accelerometer resolution to be measured. Accelerometer resolution is typically tested by using mechanical structure means to change the angle between the sensitive axis and the horizontal plane or to change the spacing between the gravity mass and the acceleration. The usual test method is to subdivide the gravitational field with an optical index head, the minimum scale of which is 0.1 ", and the highest resolution of the accelerometer which can be measured is 0.5ug. The resolution can also be tested by adopting a uniform rotation modulation method, the acceleration is arranged on a deflectable uniform rotation table top, the gravity acceleration signal is divided slightly, and the resolution of 0.1ug can be measured by utilizing the double-shaft turntable. The resolution test can be performed by adopting high specific gravity materials to generate gravitational gradient, 4 quartz flexible accelerometers are uniformly arranged on a double-shaft turntable rotating at a constant angular speed at intervals of 90 degrees, the sensitive shaft direction is the tangential direction of the rotation angular speed, and the maximum resolution of 0.01ug can be obtained by moving the shot to generate gravitational forces of different magnitudes. The resolution test method under 1g excitation is to test resolution by using a precise single-axis rotation device and to use a reference accelerometer to suppress common mode noise for judging whether the accelerometer has 1×10 -8 g magnitude resolution. Accelerometer resolution testing methods using a wobble device can provide aboutAn input acceleration on the order of 1ug. The high-resolution test method for the quartz accelerometer based on the piezoelectric deflection table is that the high-precision accelerometer is arranged on the piezoelectric deflection table, so that the piezoelectric deflection table swings at a micro angle in milliradian magnitude with a fixed frequency f, and the estimated test resolution can reach 1 multiplied by 10 -9 g。
The existing high-resolution accelerometer test schemes all need to provide tiny acceleration signal input by means of a precise rotating device or a turntable, have high requirements on environmental equipment and high cost, and the resolution available by the common resolution test scheme is limited.
Disclosure of Invention
Aiming at the current situation that the resolution test method of the high-sensitivity accelerometer needs to use a high-precision turntable or a rotating device, the cost is high and the installation is complex, the invention aims to provide the resolution test device and the resolution test method of the accelerometer by using the excitation force of the double eccentric motors, and the resolution accurate test of the high-sensitivity accelerometer can be realized on a simple device structure.
The technical scheme adopted by the invention is as follows:
1. an accelerometer resolution testing device utilizing excitation force of double eccentric motors:
the device comprises an eccentric module, a signal acquisition module, an optical platform, a stepping motor driver and a terminal computer; the optical platform is placed on the ground, two eccentric modules are fixedly installed on the upper surface of the optical platform, one end of the signal acquisition module is placed on the optical platform, the other end of the signal acquisition module is electrically connected with the terminal computer, and the input end of the eccentric module is connected with the output end of the terminal computer through a stepping motor driver.
The eccentric module comprises a stepping motor, a fixed eccentric block and an adjustable eccentric block; the stepping motor is fixedly arranged on the upper surface of the optical platform, the rotating shaft of the stepping motor is vertical to the upper surface of the optical platform, the fixed eccentric block and the adjustable eccentric block are both positioned above the optical platform, the top end of the rotating shaft of the stepping motor is connected to the eccentric positions of the fixed eccentric block and the adjustable eccentric block, the fixed eccentric block and the adjustable eccentric block are all in uniform circumferential motion around the rotating shaft of the stepping motor, and the pulse input end of the stepping motor is connected with the terminal computer through a stepping motor driver.
The signal acquisition module comprises an accelerometer and a signal acquisition system, wherein the accelerometer is arranged on the optical platform, and the output end of the accelerometer is connected with the terminal computer through the signal acquisition system; the two eccentric modules are symmetrically distributed by taking the sensitive axis of the accelerometer as the symmetry axis, and the connecting line of the stepping motor in the two eccentric modules is vertical to the sensitive axis of the accelerometer.
2. The method for testing the resolution of the accelerometer by utilizing the exciting force of the double eccentric motors comprises the following steps:
step S1), two eccentric modules are arranged on an optical platform in an axisymmetric way by taking the sensitive axis of an accelerometer as a symmetry axis, and then a target acceleration variation delta a is given;
step S2) obtaining the amplitude of the sinusoidal component of the digital electric signal under the target included angle:
step S2.1), giving a target included angle theta, and adjusting the included angle between the fixed eccentric block and the adjustable eccentric block to be the target included angle theta;
step S2.2) under the target included angle, controlling a rotating shaft of the stepping motor to rotate, then vibrating the optical platform and a sensitive shaft of the accelerometer, obtaining the amplitude of the sine component of the digital electric signal under the target included angle by using a terminal computer, and taking the amplitude of the sine component of the current digital electric signal as an initial amplitude;
step S3) obtaining the amplitude of the sine component of the digital electric signal under the adjustment included angle:
step S3.1) determining an adjustment included angle theta according to the given target acceleration variation delta a and the target included angle theta c Then the position of the adjustable eccentric block is adjusted to change the included angle between the fixed eccentric block and the adjustable eccentric block into an adjusted included angle theta c ；
Step S3.2) adjusting the included angle θ c Under the control of the rotation of the rotating shaft of the stepping motor, the vibration of the sensitive shaft of the optical platform and the accelerometer is performed, and the sine of the digital electric signal under the adjustment of the included angle is obtained by using the terminal computerThe amplitude of the component, and the amplitude of the sinusoidal component of the current digital electric signal is used as an adjustment amplitude;
step S3.3) processing according to the following formula to obtain the adjustment included angle theta c The following amplitude differences:
amplitude difference = adjustment amplitude-initial amplitude
Step S4) repeating the steps S2) -S3) for a plurality of times to obtain different adjustment included angles theta c The lower amplitude difference value is used for obtaining the average value of all the amplitude difference values as a target average amplitude difference corresponding to the target acceleration change delta a;
step S5), comparing the target acceleration variation delta a with a corresponding target average amplitude difference, and judging whether the given target acceleration variation is the target acceleration variation reaching the standard or not;
step S6) repeating the step S1) to the step S5) for a plurality of times to obtain a plurality of standard target acceleration variable quantities, and selecting the minimum value in the standard target acceleration variable quantities as the resolution of the accelerometer.
In the steps S2.2) and S3.2), the rotating shaft of the stepping motor is controlled to rotate, then the sensitive shafts of the optical platform and the accelerometer vibrate, and then the terminal computer is utilized to obtain the sine component amplitude of the digital electric signal, which comprises the following specific steps:
firstly, a terminal computer controls two stepping motor rotating shafts to run at the same rotating speed with opposite directions and the same size through a stepping motor driver, the stepping motor rotating shafts rotate and then drive a fixed eccentric block and an adjustable eccentric block to move and generate exciting force, the exciting force drives an optical platform to vibrate, and the optical platform vibrates and then drives a sensitive shaft of an accelerometer to do linear reciprocating vibration;
then, the accelerometer converts an acceleration signal under linear reciprocating vibration into an analog electric signal and inputs the analog electric signal into the signal acquisition system, the signal acquisition system converts the input analog electric signal into a digital electric signal and transmits the digital electric signal to the terminal computer, and the terminal computer is used for processing and separating out a signal sinusoidal component in the digital electric signal to obtain the amplitude of the corresponding digital electric signal sinusoidal component under the current angle.
In step S3.1), according to a given specificationDetermining an adjustment included angle theta by the target acceleration change delta a and the target included angle theta c The specific steps of (a) are as follows:
adjusting the included angle theta c The method is obtained by processing according to the following formula:
θ c ＝θ+Δθ
wherein, delta theta is the increment of the target included angle, A is the amplitude of the sinusoidal component of the acceleration signal a under the target included angle theta, delta a is the given target acceleration variation, and theta is the given target included angle.
The specific operation of the step S5):
step S5.1) comparing the target acceleration change delta a obtained in the step S4) with the corresponding target average amplitude difference, and judging whether the target acceleration change delta a meets the standard or not:
if 50% < target average amplitude difference/target acceleration variation < 150%, indicating that the target acceleration variation is up to standard;
otherwise, indicating that the target acceleration variation is the target acceleration variation which does not reach the standard;
the target acceleration change deltaa is an integer.
The exciting force generated by the stepping motor is obtained by processing according to the following formula:
wherein m is the sum of the masses of a single fixed eccentric block and a single adjustable eccentric block, r is the distance between the mass center of the fixed eccentric block and the rotating shaft of the stepping motor, ω is the rotating shaft rotating angular speed, θ p Is the actual included angle between the fixed eccentric block and the adjustable eccentric block.
And under the target included angle theta, an acceleration signal a of linear reciprocating vibration of the sensitive axis of the accelerometer is obtained by processing according to the following formula:
wherein M is the total mass of the optical platform, M is the sum of the masses of a single fixed eccentric block and a single adjustable eccentric block, r is the distance between the mass center of the fixed eccentric block and the rotating shaft of the stepping motor, ω is the rotating shaft rotating angular speed, θ is the target included angle, t is the rotating shaft rotating time,for fixing the included angle between the angular bisector of the eccentric block and the adjustable eccentric block and the sensitive axis of the accelerometer, eta is the vibration isolation efficiency of the horizontal vibration of the optical platform under the frequency of the sinusoidal component of the acceleration signal of the linear reciprocating vibration.
The invention principle of the invention is as follows:
the invention adopts a method that a stepping motor regulates and controls the reciprocating vibration of an optical platform, a rotating shaft of the stepping motor is perpendicular to the optical platform, the rotating shaft rotates to drive an eccentric block to generate centrifugal force, and the centrifugal force reacts to the stepping motor fixed with the optical platform, namely, the exciting force is:
wherein m is the sum of the masses of a single fixed eccentric block and a single adjustable eccentric block, r is the distance between the mass center of the eccentric block and the rotating shaft of the stepping motor, ω is the rotating shaft rotating angular speed, θ p Is the actual included angle between the fixed eccentric block and the adjustable eccentric block.
The fixed eccentric blocks and the adjustable eccentric blocks with the same specification are loaded on the fixed motor rotating shaft, and the included angle theta between the two eccentric blocks is changed by changing the fixed angle of the adjustable eccentric blocks p Thereby changing the magnitude of the synthetic eccentricity and adjusting the magnitude of the exciting force.
The single stepping motor rotating shaft is vertically arranged on the optical platform, the optical platform is driven to generate circular motion under the action of exciting force, when two stepping motors with the same model are operated at the same rotating speed with the same size and opposite directions, the motion generated by the optical platform is linear reciprocating vibration, the vibration generated by the optical platform drives a sensitive shaft of the accelerometer to do linear reciprocating vibration, and an acceleration signal a of the linear reciprocating vibration of the accelerometer can be written:
wherein M is the total mass of the optical platform, M is the sum of the masses of a single fixed eccentric block and a single adjustable eccentric block, r is the distance between the mass center of the fixed eccentric block and the rotating shaft of the stepping motor, ω is the rotating shaft rotating angular speed, θ p In order to fix the actual included angle between the eccentric block and the adjustable eccentric block, t is the rotation time of the rotating shaft,for the included angle between the angular bisector of the fixed eccentric block and the adjustable eccentric block and the sensitive axis of the accelerometer, the included angle is generally 0 DEG, and eta is the vibration isolation efficiency of horizontal vibration of the optical platform under the frequency f of the sinusoidal component of the acceleration signal of linear reciprocating vibration.
For example, in NAP series air-float vibration-isolating optical platforms, the weight of the top of the optical platform with the model NAP15-10 is 180kg, the vibration isolating efficiency is 88-94% when the vibration frequency in the horizontal direction is 5Hz, and the vibration isolating efficiency is 92-98% when the vibration isolating efficiency is 10 Hz. The method comprises the steps of selecting eccentric blocks in a single group of eccentric modules, loading the eccentric blocks with the total mass of 0.1kg and the maximum synthetic eccentricity of 0.05m on a stepping motor, adjusting the target included angle theta between the eccentric blocks to be 0 degrees, adjusting the rotating speed of the stepping motor to be 600r/min, enabling the reciprocating frequency of an optical platform to be 10Hz, enabling vibration isolation efficiency of the optical platform to be 95% in the horizontal direction, and calculating according to a formula to obtain the acceleration signal amplitude to be 1.1mg.
On the basis, the included angle between the two eccentric blocks is changed, so that the magnitude of the synthesized eccentricity is changed, the magnitude of exciting force is adjusted, and the amplitude of acceleration is changed. And selecting a plurality of groups of sinusoidal component amplitudes and target included angles of the acceleration signals according to the given target acceleration variation, determining target included angle increment and adjustment included angle, obtaining the average value of different output amplitude differences corresponding to the plurality of groups of target included angles and adjustment included angles under the target acceleration variation, and comparing the average value with an ideal output difference value, namely the target acceleration variation. Since the output acceleration signal is a sinusoidal signal, it is necessary to perform data processing on the output sinusoidal signal, and then average the amplitude of the plurality of acceleration peaks.
The relation of the sine component amplitude of the acceleration signal, the target acceleration variation, the target included angle and the target included angle increment satisfies the following relation:
wherein delta theta is the increment of the target included angle, A is the amplitude of the sinusoidal component of the acceleration signal under the target included angle theta, delta a is the given target acceleration variation, and theta is the given target included angle. When the target included angle theta is 0, the sine component amplitude of the acceleration signal is 1.1mg, the target included angle is selected to be 0 degrees, and the target acceleration variation is 4.2ug, and the target included angle increment is 10 degrees; if the target acceleration variation is 1.05ug, the target included angle increment is selected to be 5 degrees. If an optical stage having a larger stage weight is selected, the target acceleration variation can be further reduced. If the higher-precision regulation and control of the target included angle are improved on the basis, finer accelerometer resolution test can be realized.
The stepping motor provides power for the whole testing device, the stepping motor arranged on the optical platform is loaded with a fixed eccentric block and an adjustable eccentric block with the same specification, the eccentric block rotates to generate exciting force, and a rotating shaft of the stepping motor is vertically arranged on the optical platform to enable the optical platform to generate weak vibration in the horizontal direction; two stepping motors with the same model are installed in the same mode and run at the same rotating speed with opposite directions and the same size, so that the optical platform generates linear reciprocating vibration with adjustable amplitude in the horizontal direction. The accelerometer makes linear reciprocating motion along with the optical platform in the sensitive axis direction. And selecting a target included angle between the eccentric blocks and a target included angle increment according to the target acceleration variation, adjusting exciting force to change the amplitude of the input sinusoidal signal of the accelerometer, obtaining different output data of the accelerometer, and judging whether the resolution of the accelerometer meets the standard according to the ratio of the actual output amplitude difference value to the ideal output difference value under the target acceleration variation.
The invention has the beneficial effects that:
1. the invention provides a resolution test method for an accelerometer, which utilizes an eccentric motor, an optical platform realizes a simple and reliable measuring device, a precise turntable which is expensive and complicated to operate is not needed, the resolution test of the accelerometer with high sensitivity can be realized, and a repeated high-precision test is realized by utilizing a method for measuring amplitude, so that a criterion is provided for carefully measuring the performance and the application range of the accelerometer.
2. The test of the invention is carried out on an optical platform, the structure device is simple, the cost is low, the extremely high resolution of less than 1ug can be realized without the help of a precise rotating device, and the practicability is strong.
Drawings
FIG. 1 is an overall installation view of the device of the present invention;
fig. 2 is a block diagram of the testing principle of the method of the invention.
In the figure: 1. a stepping motor; 2. an optical platform; 3. fixing the eccentric block; 4. an adjustable eccentric block; 5. a stepper motor driver; 6. an accelerometer; 7. a signal acquisition system; 8. and a terminal computer.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in fig. 1, the device in the implementation comprises an eccentric module, a signal acquisition module, an optical platform 2, a stepping motor driver 5 and a terminal computer 8; the optical platform 2 is placed on the ground, two eccentric modules are fixedly installed on the upper surface of the optical platform 2, one end of a signal acquisition module is placed on the optical platform 2, the other end of the signal acquisition module is electrically connected with the terminal computer 8, and the input end of the eccentric module is connected with the output end of the terminal computer 8 through the stepping motor driver 5.
The stepper motor driver 5 is a digital stepper motor driver;
the eccentric module comprises a stepping motor 1, a fixed eccentric block 3 and an adjustable eccentric block 4; the stepping motor 1 is fixedly arranged on the upper surface of the optical platform 2, the rotating shaft of the stepping motor 1 is vertical to the upper surface of the optical platform 2, the fixed eccentric block 3 and the adjustable eccentric block 4 are both positioned above the optical platform 2, the top end of the rotating shaft of the stepping motor 1 is sequentially connected to the eccentric positions of the fixed eccentric block 3 and the adjustable eccentric block 4 from bottom to top, the stepping motor 1 drives the fixed eccentric block 3 and the adjustable eccentric block 4 to do uniform circular motion around the rotating shaft of the stepping motor 1, and the pulse input end of the stepping motor 1 is connected with the terminal computer 8 through the stepping motor driver 5.
The fixed eccentric block 3 is fixedly connected to the rotating shaft of the stepping motor 1, and the adjustable eccentric block 4 can be rotatably connected to the rotating shaft of the stepping motor 1 along the rotating shaft of the stepping motor 1, so that the angle between the fixed eccentric block 3 and the adjustable eccentric block 4 can be changed arbitrarily.
The signal acquisition module comprises an accelerometer 6 and a signal acquisition system 7, wherein the accelerometer 6 is arranged on the optical platform 2, and the output end of the accelerometer 6 is connected with a terminal computer 8 through the signal acquisition system 7;
the two eccentric modules are symmetrically distributed left and right by taking the sensitive axis of the accelerometer 6 as the symmetry axis, and the connecting line of the stepping motor 1 in the two eccentric modules is vertical to the sensitive axis of the accelerometer 6.
The stepping motor 1 provides power for the whole testing device, the stepping motor 1 arranged on the optical platform 2 is loaded with a fixed eccentric block 3 and an adjustable eccentric block 4 with the same specification, and the eccentric blocks 3 and 4 rotate to generate exciting force so as to enable the optical platform 2 to generate weak vibration in the horizontal direction; the optical platform 2 is vibrated horizontally and linearly in a reciprocating manner by the stepping motor 1, and only the acceleration input along the sensitive axis direction of the accelerometer 6 is tested. The connecting line of the stepping motor 1 in the two eccentric modules is perpendicular to the sensitive axis of the accelerometer 6, so that the sensitive axis of the accelerometer 6 can do linear reciprocating vibration along the axial direction of the accelerometer.
As shown in fig. 1 and fig. 2, in the implementation, a stepper motor 1 is mounted on an optical platform 2, a fixed eccentric block 3 and an adjustable eccentric block 4 are fixed on the stepper motor 1, the rotation of the stepper motor 1 causes the rotation of the fixed eccentric block 3 and the adjustable eccentric block 4 to generate centrifugal force, the centrifugal force is reacted to the stepper motor 1, the vibration of the stepper motor 1 drives the optical platform 2 to vibrate, two identical eccentric motors cause the optical platform 2 to vibrate along a linear direction, a digital stepper motor driver 5 is used for controlling the two stepper motors 1 to operate at the same rotating speed and opposite directions, an accelerometer 6 is fixed on the optical platform, an acceleration signal of the optical platform 2 is received, a signal acquisition system 7 samples an acceleration output electric signal, and signal processing and evaluation are performed on a terminal computer 8.
The method of the invention comprises the following steps:
step S1), two eccentric modules are arranged on the optical platform 2 in an axisymmetric way by taking the sensitive axis of the accelerometer 6 as a symmetry axis, then an initial target acceleration change delta a is given, and step S2) is carried out;
step S2) obtaining the amplitude of the sinusoidal component of the digital electric signal under the target included angle:
step S2.1), giving a target included angle theta, and adjusting the included angle between the fixed eccentric block 3 and the adjustable eccentric block 4 to be the target included angle theta;
step S2.2) under the target included angle, controlling the rotating shaft of the stepping motor 1 to rotate, then vibrating the sensitive shafts of the optical platform 2 and the accelerometer 6, obtaining the amplitude of the sine component of the digital electric signal under the target included angle by using the terminal computer 8, and taking the amplitude of the sine component of the current digital electric signal as the initial amplitude;
step S3) obtaining the amplitude of the sine component of the digital electric signal under the adjustment included angle;
step S3.1) determining an adjustment included angle theta according to the given target acceleration variation delta a and the target included angle theta c Then the position of the adjustable eccentric block 4 is adjusted so that the included angle between the fixed eccentric block 3 and the adjustable eccentric block 4 becomes an adjustment included angle theta c ；
Step S3.2) adjusting the included angle θ c Under the control of the rotation of the rotating shaft of the stepping motor 1, the sensitive shafts of the optical platform 2 and the accelerometer 6 vibrate, the amplitude of the sine component of the digital electric signal under the adjustment of the included angle is obtained by using the terminal computer 8, and the current digital electric signal is obtainedThe amplitude of the sinusoidal component of the signal is used as an adjustment amplitude;
step S3.3) processing according to the following formula to obtain the adjustment included angle theta c Corresponding amplitude difference:
amplitude difference = adjustment amplitude-initial amplitude
Step S4) is repeated for a plurality of times from step S2) to step S3), and when the target acceleration change delta a is the same, the included angle theta is adjusted differently c The lower amplitude difference value is used for obtaining the average value of all the amplitude difference values as a target average amplitude difference corresponding to the target acceleration change delta a;
step S5), comparing the target acceleration variation delta a with a corresponding target average amplitude difference, and judging whether the given target acceleration variation meets the standard or not;
step S6) the target acceleration variation is given again, then the steps S2) -S5) are repeated for a plurality of times according to different target acceleration variation deltaa, a plurality of standard target acceleration variation is obtained, and the minimum value in the standard target acceleration variation is selected as the resolution of the accelerometer 6.
In the step S2.2) and the step S3.2), under different angles, the rotating shaft of the stepping motor 1 is controlled to rotate, then the sensitive shafts of the optical platform 2 and the accelerometer 6 vibrate, and then the terminal computer 8 is utilized to obtain the sine component amplitude of the digital electric signal under different angles, which comprises the following specific steps:
firstly, a terminal computer 8 controls the rotating shafts of two stepping motors 1 to run at the same rotating speed with opposite directions through a stepping motor driver 5, the rotating shafts of the stepping motors 1 rotate and then drive a fixed eccentric block 3 and an adjustable eccentric block 4 to move and generate exciting force, the exciting force drives an optical platform 2 to vibrate, and a sensitive shaft of an accelerometer 6 is driven to do linear reciprocating vibration after the optical platform 2 vibrates;
meanwhile, the rotating speed of the stepping motor 1 is regulated and controlled to enable the frequency of the sinusoidal component of the acceleration signal of the linear reciprocating vibration of the accelerometer 6 to be f;
then, the accelerometer 6 converts an acceleration signal under the linear reciprocating vibration into an analog electric signal, the analog electric signal is input into the signal acquisition system 7, the signal acquisition system 7 converts the input analog electric signal into a digital electric signal and transmits the digital electric signal to the terminal computer 8, the terminal computer 8 is used for processing and separating a signal sinusoidal component with the frequency f in the digital electric signal, and the amplitude of the corresponding digital electric signal sinusoidal component is obtained when the frequency of the acceleration signal sinusoidal component is f under the current angle.
In step S3.1), an adjustment included angle theta is determined according to the given target acceleration variation delta a and the target included angle theta c The specific steps of (a) are as follows:
adjusting the included angle theta c The method is obtained by processing according to the following formula:
θ c ＝θ+Δθ
wherein delta theta is the increment of a target included angle, a is the amplitude of a sinusoidal component of an acceleration signal a of linear reciprocating vibration of a sensitive axis of the accelerometer (6) under the target included angle theta, delta a is a given target acceleration variation, and theta is a given target included angle.
The specific operation of step S5):
comparing the target acceleration change delta a obtained in the step S4) with the corresponding target average amplitude difference, and judging whether the target acceleration change delta a meets the standard or not:
if 50% < the corresponding target average amplitude difference/target acceleration variation < 150%, indicating that the target acceleration variation meets the standard;
otherwise, the target acceleration variation is not up to standard;
wherein the target acceleration variation Δa is an integer.
The specific operation of step S6) is:
step S6.1), judging whether the given initial target acceleration variation reaches the standard:
if the standard is reached, the step S6.2 is carried out;
otherwise, go to step S6.3);
step S6.2) giving a new target acceleration variation Δa i ：
Δa i ＝Δa-i
Wherein, the subscript i represents the cycle number, and Δa represents the target acceleration variation which is initially set;
continuously reducing and updating the value of the target acceleration variation, namely when the initial target acceleration variation is given by 100, the acceleration variation given next is 99, 98 and 97 in sequence, and so on;
substituting the updated target acceleration variation into the step S2) -the step S5) for testing, and judging whether the target acceleration variation meets the standard or not; and ending the test until the target acceleration variation becomes unqualified, and taking the target acceleration variation which is qualified for the last time as the resolution of the accelerometer 6.
Step S6.3) giving a new target acceleration variation Δa i ：
Δa i ＝Δa-i
Continuously increasing and updating the value of the target acceleration variation, namely when the initial target acceleration variation is given by 100, the acceleration variation given next is sequentially 101, 102 and 103, and so on;
substituting the updated target acceleration variation into the step S2) -the step S5) for testing, and judging whether the target acceleration variation meets the standard or not; and ending the test until the target acceleration change becomes standard, and taking the target acceleration change reaching the standard as the resolution of the accelerometer 6.
The exciting force generated by the stepping motor 1 is obtained by processing according to the following formula:
wherein m is the sum of the masses of the single fixed eccentric block 3 and the single adjustable eccentric block 4, r is the distance between the mass center of the fixed eccentric block 3/the adjustable eccentric block 4 and the rotating shaft of the stepping motor 1, ω is the rotating shaft rotating angular speed, θ p Is the actual included angle between the fixed eccentric block 3 and the adjustable eccentric block 4.
In particular implementation, θ p For the object clampAngle theta or adjusting angle theta c The method comprises the steps of carrying out a first treatment on the surface of the The fixed eccentric block 3 and the adjustable eccentric block 4 have the same size, model and mass, and the distances between the mass centers of the fixed eccentric block 3 and the adjustable eccentric block 4 and the rotating shaft of the stepping motor 1 are the same.
And under the target included angle theta, the acceleration signal sinusoidal component a of the linear reciprocating vibration of the sensitive axis of the accelerometer 6 is obtained by processing according to the following formula:
wherein M is the total mass of the optical platform 2, M is the sum of the masses of the single fixed eccentric block 3 and the single adjustable eccentric block 4, r is the distance between the mass center of the fixed eccentric block 3 and the rotating shaft of the stepping motor 1, ω is the rotating shaft rotating angular velocity, θ is the target included angle, t is the rotating shaft rotating time,in order to fix the included angle between the angular bisector of the eccentric block 3 and the adjustable eccentric block 4 and the sensitive axis of the accelerometer 6, eta is the horizontal vibration isolation efficiency of the optical platform 2 under the frequency f of the sinusoidal component of the acceleration signal of the linear reciprocating vibration.
Claims (9)
1. An accelerometer resolution testing device utilizing excitation force of double eccentric motors is characterized in that:
comprises an eccentric module, a signal acquisition module, an optical platform (2), a stepping motor driver (5) and a terminal computer (8); the optical platform (2) is placed on the ground, two eccentric modules are fixedly arranged on the upper surface of the optical platform (2), one end of the signal acquisition module is placed on the optical platform (2), the other end of the signal acquisition module is electrically connected with the terminal computer (8), and the input end of the eccentric module is connected with the output end of the terminal computer (8) through the stepping motor driver (5).
2. The accelerometer resolution testing apparatus according to claim 1, wherein the accelerometer resolution testing apparatus uses excitation forces of the double eccentric motors, wherein: the eccentric module comprises a stepping motor (1), a fixed eccentric block (3) and an adjustable eccentric block (4); the stepping motor (1) is fixedly arranged on the upper surface of the optical platform (2), the rotating shaft of the stepping motor (1) is perpendicular to the upper surface of the optical platform (2), the fixed eccentric block (3) and the adjustable eccentric block (4) are located above the optical platform (2), the top end of the rotating shaft of the stepping motor (1) is connected to the eccentric position of the fixed eccentric block (3) and the adjustable eccentric block (4), the fixed eccentric block (3) and the adjustable eccentric block (4) do uniform circular motion around the rotating shaft of the stepping motor (1), and the pulse input end of the stepping motor (1) is connected with the terminal computer (8) through the stepping motor driver (5).
3. An accelerometer resolution testing apparatus utilizing excitation force of double eccentric motors according to claim 2, wherein: the signal acquisition module comprises an accelerometer (6) and a signal acquisition system (7), wherein the accelerometer (6) is arranged on the optical platform (2), and the output end of the accelerometer (6) is connected with the terminal computer (8) through the signal acquisition system (7);
the two eccentric modules are symmetrically distributed by taking the sensitive axis of the accelerometer (6) as the symmetrical axis, and the connecting line of the stepping motor (1) in the two eccentric modules is vertical to the sensitive axis of the accelerometer (6).
4. A method for testing the resolution of an accelerometer using excitation forces of a double eccentric motor applied to the device of any one of claims 1 to 3, comprising the steps of:
step S1), two eccentric modules are arranged on an optical platform (2) in an axisymmetric way by taking the sensitive axis of an accelerometer (6) as a symmetry axis, and then a target acceleration variation delta a is given;
step S2) obtaining the amplitude of the sinusoidal component of the digital electric signal under the target included angle:
step S2.1), setting a target included angle theta, and adjusting the included angle between the fixed eccentric block (3) and the adjustable eccentric block (4) to be the target included angle theta;
step S2.2) under the target included angle, controlling a rotating shaft of the stepping motor (1) to rotate, then vibrating a sensitive shaft of the optical platform (2) and the accelerometer (6), obtaining the amplitude of a sine component of the digital electric signal under the target included angle by using a terminal computer (8), and taking the amplitude of the sine component of the current digital electric signal as an initial amplitude;
step S3) obtaining the amplitude of the sine component of the digital electric signal under the adjustment included angle:
step S3.1) determining an adjustment included angle theta according to the given target acceleration variation delta a and the target included angle theta c Then the position of the adjustable eccentric block (4) is adjusted so that the included angle between the fixed eccentric block (3) and the adjustable eccentric block (4) becomes an adjustment included angle theta c ；
Step S3.2) adjusting the included angle θ c Controlling a rotating shaft of the stepping motor (1) to rotate, vibrating sensitive shafts of the optical platform (2) and the accelerometer (6), obtaining the amplitude of the sine component of the digital electric signal under an adjustment included angle by using a terminal computer (8), and taking the amplitude of the sine component of the current digital electric signal as an adjustment amplitude;
step S3.3) processing according to the following formula to obtain the adjustment included angle theta c The following amplitude differences:
amplitude difference = adjustment amplitude-initial amplitude
Step S4) repeating the steps S2) -S3) for a plurality of times to obtain different adjustment included angles theta c The lower amplitude difference value is used for obtaining the average value of all the amplitude difference values as a target average amplitude difference corresponding to the target acceleration change delta a;
step S5), comparing the target acceleration variation delta a with a corresponding target average amplitude difference, and judging whether the given target acceleration variation is the target acceleration variation reaching the standard or not;
step S6) repeating the step S1) to the step S5) for a plurality of times to obtain a plurality of standard target acceleration variable quantities, and selecting the minimum value in the standard target acceleration variable quantities as the resolution of the accelerometer (6).
5. The method for testing the resolution of the accelerometer by using the excitation force of the double eccentric motor according to claim 4, wherein the method comprises the following steps: in the steps S2.2) and S3.2), the rotating shaft of the stepping motor (1) is controlled to rotate, then the sensitive shafts of the optical platform (2) and the accelerometer (6) vibrate, and then the terminal computer (8) is utilized to obtain the specific steps of the sine component amplitude of the digital electric signal:
firstly, a terminal computer (8) controls the rotating shafts of two stepping motors (1) to run at the same rotating speed with opposite directions through a stepping motor driver (5), the rotating shafts of the stepping motors (1) rotate and then drive a fixed eccentric block (3) and an adjustable eccentric block (4) to move and generate exciting force, the exciting force drives an optical platform (2) to vibrate, and the optical platform (2) drives a sensitive shaft of an accelerometer (6) to do linear reciprocating vibration;
then, the accelerometer (6) converts an acceleration signal under the linear reciprocating vibration into an analog electric signal and inputs the analog electric signal into the signal acquisition system (7), the signal acquisition system (7) converts the input analog electric signal into a digital electric signal and transmits the digital electric signal to the terminal computer (8), and the terminal computer (8) is used for processing and separating out a signal sinusoidal component in the digital electric signal to obtain the amplitude of the corresponding digital electric signal sinusoidal component under the current angle.
6. The method for testing the resolution of the accelerometer by using the excitation force of the double eccentric motor according to claim 4, wherein the method comprises the following steps: in the step S3.1), an adjustment angle θ is determined according to the given target acceleration variation Δa and the target angle θ c The specific steps of (a) are as follows:
adjusting the included angle theta c The method is obtained by processing according to the following formula:
θ c ＝θ+Δθ
wherein, delta theta is the increment of the target included angle, A is the amplitude of the sinusoidal component of the acceleration signal a under the target included angle theta, delta a is the given target acceleration variation, and theta is the given target included angle.
7. The method for testing the resolution of the accelerometer by using the excitation force of the double eccentric motor according to claim 4, wherein the method comprises the following steps: the specific operation of the step S5) is as follows:
step S5.1) comparing the target acceleration change delta a obtained in the step S4) with the corresponding target average amplitude difference, and judging whether the target acceleration change delta a meets the standard or not:
if 50% < target average amplitude difference/target acceleration variation < 150%, indicating that the target acceleration variation is up to standard;
otherwise, indicating that the target acceleration variation is the target acceleration variation which does not reach the standard;
the target acceleration change deltaa is an integer.
8. The method for testing the resolution of the accelerometer by using the excitation force of the double eccentric motor according to claim 5, wherein the method comprises the following steps: the exciting force generated by the stepping motor (1) is obtained by processing according to the following formula:
wherein m is the sum of the masses of a single fixed eccentric block (3) and a single adjustable eccentric block (4), r is the distance between the mass center of the fixed eccentric block (3) and the rotating shaft of the stepping motor (1), ω is the rotating shaft rotating angular speed, θ p Is an actual included angle between the fixed eccentric block (3) and the adjustable eccentric block (4).
9. The method for testing the resolution of the accelerometer by using the excitation force of the double eccentric motors according to claim 6, wherein the method comprises the following steps: and under the target included angle theta, an acceleration signal a of linear reciprocating vibration of a sensitive shaft of the accelerometer (6) is obtained by processing according to the following formula:
wherein M is the total mass of the optical platform (2), and M is a single fixed eccentric block (3) and a singleThe sum of the masses of the adjustable eccentric blocks (4), r is the distance between the mass center of the fixed eccentric block (3) and the rotating shaft of the stepping motor (1), ω is the rotating shaft rotating angular speed, θ is the target included angle, t is the rotating shaft rotating time,for fixing the included angle between the angular bisector of the eccentric block (3) and the adjustable eccentric block (4) and the sensitive axis of the accelerometer (6), eta is the vibration isolation efficiency of the horizontal vibration of the optical platform (2) under the frequency of the sinusoidal component of the acceleration signal of the linear reciprocating vibration.
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