CN111947684B - Inertial platform swinging dynamic precision testing method based on gravity vector measurement - Google Patents
Inertial platform swinging dynamic precision testing method based on gravity vector measurement Download PDFInfo
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Abstract
A method for testing the swinging dynamic precision of an inertial platform based on gravity vector measurement comprises the steps of measuring a gravity vector through a quartz accelerometer, and reflecting the posture change of a platform body of the platform by using a projection angle of the gravity vector on the platform body; in the swinging process, the platform body of the inertial platform is stabilized in an inertial space, the horizontal drift of the inertial platform is resolved through the specific force output of the quartz accelerometer in the horizontal direction in the swinging process, meanwhile, a value window is designed according to the error of the measuring method and the output characteristic of the quartz accelerometer, and the dynamic swinging precision of the inertial platform is obtained through calculating the static and dynamic differences of the inertial platform. The platform body posture of the inertial platform can only measure two horizontal directions of the inertial platform, and the drift of the azimuth axis can not be observed, so that the transposition of the inertial platform base is realized through the position swing platform, the swing modes of the vertical state of the inertial platform and the horizontal state of the inertial platform are designed in sequence, the observation problem of the azimuth axis is solved, errors caused by various non-product factors are eliminated, and the swing performance of the inertial platform is accurately and efficiently evaluated.
Description
Technical Field
The invention relates to a method for testing the swing dynamic precision of an inertial platform based on gravity vector measurement, and belongs to the technical field of inertial platform system testing methods.
Background
The inertial platform is a stable platform system for measuring attitude information and apparent acceleration of a carrier, and consists of a gyroscope, a platform body, a frame system and a stable loop. The gyroscope mounted on the platform senses the angular velocity of the platform body relative to the inertial space and controls the angular velocity through the stabilizing loop, so that the platform body is kept stable in the inertial space. When the platform base makes periodic angular motion, the angular position of the platform body of the platform contains dynamic errors, and the purpose of the swing test is to evaluate the stable control performance of the platform system under the dynamic condition of the three-axis swing angle of the platform system. Only by adopting the swing evaluation method, the influence of errors caused by non-product factors is eliminated as much as possible, and the dynamic performance of the inertia platform can be evaluated more accurately, stably and efficiently.
The current swing dynamic precision test method adopted by the inertial platform is to measure and calculate the swing drift by taking a speed swing platform as an angle dynamic excitation device and taking a frame angle at the shaft end of the platform as an observed quantity. The method is based on the linear characteristic of a small-angle drift curve of a frame angle, and the drift of the frame angle approximately represents the drift of an inertial platform system. The current swing drift test method has a high swing out-of-tolerance ratio, especially for azimuth lock axes. During swinging, the platform works as a follow-up mode, the azimuth shaft adopts a frame locking mode, the horizontal two shafts adopt a leveling mode, and the platform base is directly and fixedly connected with the swinging table. Because the swing table has zero return errors, the horizontal shaft can reduce the out-of-tolerance through initial zero compensation during leveling during testing, but the follow-up shaft adopts a frame angle lock zero mode, the zero return errors of the swing table cannot be identified, and therefore the locking shaft out-of-tolerance ratio is high.
In addition, the manual pulling and inserting of the positioning pin in the swing test can cause inconsistent changes of the frame angle curve, the window value cannot be fixed during calculation, and the error influence of the method is further increased. In the current 10-minute swing test time, the influence of the error of the method on the swing drift result can maximally exceed 0.01 degrees/h. Therefore, the current method for evaluating the swing of the inertial platform is obviously influenced by errors of non-product factors and cannot essentially solve the problem of compensating the azimuth locking axis.
Disclosure of Invention
The technical problem of the invention is solved: the method overcomes the defects that the existing evaluation method is large in error and easy to be influenced by non-product factors, provides the method for testing the swing dynamic precision of the inertial platform based on gravity vector measurement, and solves the problem that the swing dynamic precision of the inertial platform system is long-term out of tolerance.
The technical solution of the invention is as follows:
a method for testing the swing dynamic precision of an inertial platform based on gravity vector measurement comprises the following steps:
(1) setting a swing test environment;
(2) carrying out a swing test of the inertia platform in a vertical state;
(3) carrying out a swing test of the inertia platform in a horizontal state;
(4) calculating the gravity vector output of the inertial platform in a space stable state;
(5) performing attitude calculation on the inertial platform based on the gravity vector output;
(6) and calculating the swing drift rate of the inertial platform in a fixed window value taking mode.
Further, the setting of the swing test environment specifically includes: selecting a position swing table to carry out a swing test, placing an inertial platform on the position swing table, electrifying the inertial platform after the inertial platform is installed, and stabilizing the inertial platform according to the requirement of the precision stabilization time of a gyroscope and a quartz accelerometer; the inner ring, the middle ring and the outer ring of the swing table are arranged according to swing test conditions, and the swing test conditions comprise that: three rings are arranged to swing according to sine wave with the same frequency and amplitude, and the phase difference between two adjacent shafts is the same.
Further, the frequency value is set to 1Hz, the amplitude is set to 6 +/-0.5 degrees, and the phase difference between two adjacent axes is not more than 45 degrees.
Furthermore, the position swing platform is provided with three rotating rings, namely an inner ring, a middle ring and an outer ring, which can rotate continuously for 360 degrees, and the position swing platform controls the transposition and the swing of each ring through a control system comprising a photoelectric encoder and a shaft end motor.
Further, performing a swing test of the inertia platform in a vertical state, firstly performing a static drift test of the inertia platform, then continuously performing two dynamic drift tests of the inertia platform in a swing state, and finally performing a static drift test of the inertia platform; the method specifically comprises the following steps:
(2.1) returning the swing platform to zero, and sending an indexing command of any position by the inertial platform to enable attitude angles of X, Y and Z axes to be 0 degree;
(2.2) after waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second;
(2.3) starting the static drift test of the inertial platform, keeping the swing table still, and sending an index command at any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(2.4) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second; starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(2.5) repeating the step (2.4) and testing the dynamic drift of the inertial platform once;
and (2.6) repeating the step (2.3) and testing the static drift of the inertial platform once.
Further, after the swing test of the inertia platform in the vertical state is completed, the inner ring of the swing platform is rotated by 90 degrees, so that the inertia platform is converted into the horizontal state to carry out the swing test of the inertia platform in the horizontal state, firstly, the static drift test of the inertia platform is carried out, then, the dynamic drift test of the inertia platform in the swing state is continuously carried out for two times, and finally, the static drift test of the inertia platform is carried out again; the method specifically comprises the following steps:
(3.1) returning the swing platform to the initial position, wherein the inner ring is 90 degrees, the middle ring is 0 degree, and the outer ring is 0 degree;
(3.2) sending an indexing command of any position by the inertial platform to enable attitude angles of X, Y and Z axes to be 0 degree;
(3.3) after waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second;
(3.4) starting the static drift test of the inertial platform, keeping the swing table still, and sending an index command of any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(3.5) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second; starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(3.6) repeating the step (3.5) and testing the dynamic drift of the inertial platform once;
and (3.7) repeating the step (3.4) and testing the static drift of the inertial platform once.
Further, the step (4) of calculating the gravity vector output of the inertial platform in the space stable state specifically includes:
(4.1) after the vertical state swing test, respectively acquiring four groups of quartz accelerometer data of the inertial platform in two horizontal directions, and acquiring four groups of quartz accelerometer data of the inertial platform in the other direction after the horizontal state swing test;
(4.2) carrying out low-pass filtering on the quartz accelerometer data in three directions, and then calculating the original specific force output of the quartz accelerometer
Wherein:
and
respectively representing pulse output of a positive channel and a negative channel of the quartz accelerometer, delta t is the time interval of the pulse output, K 0j1.25g And K 1j1.25g Representing zero-order terms and first-order terms of the quartz accelerometer, and j representing the axial directions of three inertial platforms of x, y and z;
and (4.3) sorting the specific force output of the quartz accelerometer in the x direction, the y direction and the z direction to obtain a gravity vector measurement result of the inertial platform in a space stable state.
Further, the step (5) of performing attitude calculation on the inertial platform based on the gravity vector output specifically includes:
(5.1) carrying out inertial platform installation error compensation on the specific force output of the quartz accelerometer, and solving the specific force output f of the quartz accelerometer on the inertial platform coordinate system after the installation error of the compensation system p ：
Wherein the content of the first and second substances,
and (3) representing a mounting error compensation matrix of the quartz accelerometer in an inertial platform coordinate system:
Q xz 、Q xy respectively representing the included angles Q between the X-axis quartz accelerometer and the Z axis and the Y axis of the coordinate system of the inertial platform yz 、Q yx Respectively representing the included angles Q between the Y-axis quartz accelerometer and the Z axis and the X axis of the coordinate system of the inertial platform zy 、Q zx Respectively representing the included angles between the Z-axis quartz accelerometer and the Y-axis and the X-axis of the inertial platform coordinate system;
(5.2) let d x 、d y And d z Representing the angle of the platform drift about the inertial platform coordinate system X, Y and the Z-axis respectively,
the drift angles of the inertial platform in the horizontal axis direction corresponding to different states of the base are as follows:
further, the step (6) calculates the swing drift rate of the inertial platform by means of fixed window value taking, specifically:
(6.1) drawing the drift angle curves of the three axes of the inertia platform obtained by resolving to obtain an attitude drift curve of the whole swing drift process of the inertia platform;
(6.2) according to the drift curve, carrying out value calculation after the quartz accelerometer of the inertial platform body deviates from the leveling position and is stably output, and determining initial t for calculating the platform drift angular velocity 0 Time value, and t after the end of oscillation 1 The time value and the window size are set as delta T, and then the swinging drift angular velocity is calculated for each flight navigation curve fixed window value totaling T seconds, namely the angular velocity of static or dynamic drift is as follows:
and i is x, y and z, and represents the three platform axis directions of x, y and z.
Further, calculating the swing drift rate of the inertial platform, namely calculating the difference between the two dynamic drift angular velocities and the average value of the two static drift angular velocities:
δ ωr ＝(ω r1 +ω r2 -ω s1 -ω s2 )/2
in the formula: omega r1 The first dynamic drift angular velocity; omega r2 Angular velocity for the second dynamic drift; omega s1 Angular velocity for the first static drift; omega s2 The angular velocity of the second static drift.
Compared with the prior art, the invention has the following advantages:
(1) the invention has the advantages of no influence of the precision of the test equipment (swing table) in the test process, small measurement error and capability of avoiding the defect that the error of the swing table is transmitted one by the frame angle method. The position swing table is used as excitation equipment for angular dynamics of an inertial platform system, the position swing table is used for controlling the platform base to rotate during a swing test, the quartz accelerometer in the vertical direction is rotated to be horizontal, and the problem that an azimuth axis cannot be observed is solved through inertial space attitude matrix transformation.
(2) The invention directly reflects the drift of the platform body through the specific force output of the high-precision quartz accelerometer, the error of the quartz accelerometer method is obviously smaller than that of the frame angle method, the dynamic drift process of the platform in the swinging process can be visually observed, and the overall dynamic drift process of the platform can be controlled.
(3) The invention can realize the base transposition of the inertia platform by using the position swing platform, and can essentially solve the problem of over-tolerance in the direction locking and swinging of the platform.
(4) According to the invention, the gravity vector is measured by the horizontal quartz accelerometer arranged on the platform body of the platform, the quartz accelerometer on the platform body does not move angularly along with the base, the dynamic and static changes of the posture of the platform body are reflected by the horizontal projection angle of the gravity vector on the platform body, and the real-time drift of the inertial platform can be directly solved through the specific force output of the quartz accelerometer. And a small-range quartz accelerometer is selected for measuring the gravity vector, and the high-precision characteristic of the small-range quartz accelerometer is fully utilized, so that the accuracy of the gravity vector measurement is ensured.
(5) According to the invention, the fixed window value is taken after the quartz accelerometer is stably output at a certain angle when the platform body deviates from the leveling position, so that the influence of the output dead zone of the quartz accelerometer is effectively avoided, and the swing drift rate of the inertial platform is obtained by calculating the dynamic and static differences of the swing drift curve.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a flow chart of the process of static and dynamic drifting with the inertial platform vertical;
FIG. 3 is a flow chart of the process of static drift and dynamic drift in the horizontal-vertical state of the inertial platform;
FIG. 4 is a schematic diagram of a window selection for calculating the swing drift of the inertial platform.
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings.
The invention provides a method for testing the swing dynamic precision of an inertial platform based on gravity vector measurement. Measuring a gravity vector by a quartz accelerometer arranged on the platform body, and reflecting the posture change of the platform body by a projection angle of the gravity vector on the platform body; in the swinging process, the platform body is stabilized in an inertial space, the horizontal drift of the platform is resolved through the specific force output of the quartz accelerometer in the horizontal direction in the swinging process, meanwhile, a value window is designed according to the error of the measuring method and the output characteristic of the quartz accelerometer, and the dynamic precision of the platform swinging is obtained through calculating the static and dynamic differences of the inertial platform. The platform body posture can only measure two horizontal directions of the platform, and the drift of the azimuth axis can not be observed, so that the platform system base transposition is realized through the position swing platform, the swing modes of the base in the vertical state and the base in the horizontal state are designed in sequence, and the observation problem of the azimuth axis is solved. By the method for testing the swing dynamic precision, errors caused by various non-product factors are eliminated, and the swing performance of the high-precision inertial platform is more accurately and efficiently evaluated.
The position of the swing platform is selected during the swing test of the inertial platform, the swing platform is provided with three rotating rings of an inner ring, a middle ring and an outer ring, the swing platform can continuously rotate for 360 degrees, and the swing platform can accurately control the transposition and the swing of each ring through a set of control system comprising a photoelectric encoder and a shaft end motor.
The invention provides a gravity vector measurement-based method for testing the swing dynamic precision of an inertial platform, which comprises the following specific steps as shown in figure 1:
(1) setting a sway test Environment
The inertial platform is placed on the position swing platform, the system is powered on after the platform is installed, and the performance of the platform system is stable according to the requirement of the precision stability time of the gyroscope and the quartz accelerometer. The inner ring, the middle ring and the outer ring of the swing table are provided with three rings swinging according to sine waveforms with the same frequency and the same amplitude according to the swinging test conditions in the table 1, and the initial phase difference of the three swinging waveforms is not more than 45 degrees in sequence.
TABLE 1 rocking test conditions
| Frequency (Hz) | Amplitude (°) | Phase difference (°) between two adjacent axes |
| 1 | 6±0.5 | ≤45 |
The position swing table is used as excitation equipment for angular dynamics of the platform system, the platform base is controlled to rotate through the position swing table during swing tests, the quartz accelerometer in the vertical direction is rotated to be horizontal, and the problem that the azimuth axis cannot be observed is solved through inertial space attitude matrix transformation.
(2) Vertical state swing test of inertia platform
During the swing test, the inertial platform is in a space stable (flight navigation) state during static drift and dynamic drift, the static drift 1-dynamic drift 2-static drift 2 are performed according to the sequence, the test processes of the static drift twice are completely the same, the test processes of the dynamic drift twice are also completely the same, and the specific operation flow of the platform and the swing platform is shown in fig. 2. Firstly, carrying out a static drift test of the inertial platform, then continuously carrying out a dynamic drift test of the inertial platform under a two-time swing state, and finally carrying out a static drift test of the inertial platform. The testing time of each drift rate is T seconds (T is 600 seconds), in the dynamic drift process, the swing table does not swing all the time, and a period of static drift time is reserved before and after the swing.
As shown in fig. 2, the specific steps of performing the inertial platform vertical state swing test include:
(a) the swing platform returns to zero, the inertial platform sends an indexing command at any position, and the attitude angles of X, Y and Z axes are 0 degree;
(b) after waiting for 180 seconds, the inertial platform is switched to a small-range quartz accelerometer flight navigation state, and the moment is taken as a time zero point (0 second);
(c) starting the static drift test of the inertial platform, keeping the swing table still, and sending an indexing command of any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(d) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a small-range quartz accelerometer flight navigation state, and taking the moment as a time zero point (0 second); starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(e) repeating the (d) dynamic drift test of the inertial platform once;
(f) repeating (c) the inertial platform static drift test once.
(3) Performing a horizontal state swing test of an inertial platform
And after the swing test of the inertia platform in the vertical state is finished, performing the swing test of the inertia platform in the horizontal state. Before the test is started, the inner ring of the swing platform needs to be rotated by 90 degrees to enable the platform base to be horizontal, and then the swing test in the state is formally started. The swing test process in this state is exactly the same as in the vertical state, and the specific flow of the platform and the swing platform is shown in fig. 3. Time nodes are strictly controlled in the test process, two groups of swing processes are ensured to be completely the same, and the consistency of the selection of the swing drift calculation time nodes is required.
As shown in fig. 3, the specific steps of performing the horizontal state swing test of the inertial platform include:
(a) the swing table returns to the initial position (the inner ring is 90 degrees, the middle ring is 0 degree, and the outer ring is 0 degree);
(b) the inertial platform sends an indexing instruction at any position to enable attitude angles of X, Y and Z axes to be 0 degree;
(c) after waiting for 180 seconds, the inertial platform is switched to a small-range quartz accelerometer flight navigation state, and the moment is taken as a time zero point (0 second);
(d) starting the static drift test of the inertial platform, keeping the swing table still, and sending an indexing command of any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(e) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a small-range quartz accelerometer flight navigation state, and taking the moment as a time zero point (0 second); starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(f) repeating (e) the dynamic drift test of the inertial platform once;
(g) repeating (d) the inertial platform static drift test once.
(4) After the swing test, calculating to obtain the gravity vector output of the inertial platform in a space stable state:
(4.1) after the vertical state swing test, respectively acquiring four groups of quartz accelerometer data of the inertial platform in two horizontal directions, and acquiring four groups of quartz accelerometer data of the inertial platform in the other direction after the horizontal state swing test;
(4.2) carrying out low-pass filtering on the quartz accelerometer data in three directions, and then calculating the original specific force output of the quartz accelerometer
Wherein:
and
respectively representing pulse output of a positive channel and a negative channel of the quartz accelerometer, delta t is the time interval of the pulse output, K 0j1.25g And K 1j1.25g Represents the zero-order term and the first-order term of a small-range (here, 1.25g) quartz accelerometer, and j represents the directions of three platform axes of x, y and z;
and (4.3) sorting the specific force output of the quartz accelerometer in the x direction, the y direction and the z direction to obtain a gravity vector measurement result of the inertial platform in a space stable state.
(5) The attitude calculation is carried out on the inertial platform based on the gravity vector measurement, and the specific process is as follows:
(5.1) carrying out platform installation error compensation on the specific force output of the quartz accelerometer, and solving the specific force output f of the quartz accelerometer on the inertial platform system after the installation error of the compensation system p ：
Wherein
Representing the raw specific force output of the j-direction quartz accelerometer,
and (3) representing a mounting error compensation matrix of the quartz accelerometer in an inertial platform coordinate system:
Q xz 、Q xy respectively representing the included angles Q between the X quartz accelerometer and the Z axis and the Y axis of the platform coordinate system yz 、Q yx Respectively representing the included angles Q between the Y quartz accelerometer and the Z axis and the X axis of the platform coordinate system zy 、Q zx Respectively representing the included angles between the Z quartz accelerometer and the Y axis and the X axis of the platform coordinate system;
(5.2) selecting a 'north-sky-east' geographical coordinate system as a navigation reference coordinate system, recording as an n system, and defining: f. of n Representing specific forces, ω, on the navigation system ie n Representing the angular velocity, v, of the earth system relative to the inertial system in a navigation system n Linear velocity, g, of a navigation system n Representing the acceleration of gravity on the navigation system,
representing the direction cosine matrix from the platform system to the navigation system.
According to the specific force equation of the inertial navigation system:
when the platform is not in line motion,
v n ＝0。
according to
Further transformation yields:
the attitude of the platform can be represented by an attitude matrix composed of rotation angles about three axes, i.e., the drift angles of the platform body about each axis direction.
Let d x 、d y And d z Representing the drift angles of the platform about the X, Y and Z axes, respectively
Substituting the above relationship into
Can be simplified to obtain:
resolving under a small angle condition, and respectively obtaining the following drift angles in the horizontal axis direction when the inertia platform is in different states:
d x ＝arcsin(f z p )，
(6) and (4) calculating and solving the swing drift rate of the inertial platform by using the fixed window value. And after the platform body deviates from the leveling position by a certain angle and the quartz accelerometer is stably output, the value of the fixed window is taken, so that the influence of the output dead zone of the quartz accelerometer is effectively avoided, and the swing drift rate of the inertial platform is obtained by calculating the dynamic and static differences of the swing drift curve.
The specific implementation process is as follows:
(6.1) drawing the drift angle curves of the three axes of the inertia platform obtained by resolving to obtain an attitude drift curve of the whole process of the platform swing drift;
and (6.2) according to the drift curve, carrying out value calculation after the quartz accelerometer is stably output when the platform body deviates from the leveling position, and effectively avoiding the influence of the quartz accelerometer output dead zone on the calculation precision. Under the common drive of platform gyro drift and ground speed, the platform body can drift away from the leveling position gradually, and for different inertial platforms, the initial t for calculating the platform drift angular velocity needs to be determined according to the gyro drift characteristics of the inertial platforms, the resolution of the inertial-navigation-level quartz accelerometer and the requirements of an installation error system 0 Time value, and t after the end of oscillation 1 The time value and the window size are set as Δ T, as shown in fig. 4, then a fixed window value is taken for each flight navigation data curve (T seconds in total), and the sway drift angular velocity is calculated, that is, the angular velocity of the static or dynamic drift is:
(i ═ x, y, z), where i denotes the three platform axis directions x, y, and z;
(6.3) the swing drift rate of the inertial platform is the difference between the two dynamic drift angular velocities and the average value of the two static drift angular velocities:
δ ωr ＝(ω r1 +ω r2 -ω s1 -ω s2 )/2，
in the formula: omega r1 First dynamic drift angular velocity, ω r2 Angular velocity of the second dynamic drift, ω s1 Angular velocity of the first static drift, ω s2 -angular velocity of the second static drift.
The invention provides a method for testing the swing dynamic precision of an inertial platform based on gravity vector measurement, which solves the problem that the swing dynamic precision of an inertial platform system is long-term out of tolerance. And the platform system base is controlled to rotate through the high-precision position swing platform, and the swing drift of the platform under the condition of no linear motion is output and evaluated according to the specific force of the high-precision quartz accelerometer arranged on the platform body. 1 x 10 quartz accelerometer according to inertial navigation grade -5 The method error can be controlled within the range of 0.0038/h at the precision level of magnitude.
The invention has the advantages of no influence of the precision of the test equipment (swing table) in the test process, small measurement error and capability of avoiding the defect that the error of the swing table is transmitted one by the frame angle method. The position swing table is used as excitation equipment for angular dynamics of the platform system, the platform base is controlled to rotate through the position swing table during swing tests, the quartz accelerometer in the vertical direction is rotated to be horizontal, and the problem that the azimuth axis cannot be observed is solved through inertial space attitude matrix transformation. The invention directly reflects the drift of the platform body through the specific force output of the high-precision quartz accelerometer, the error of the quartz accelerometer method is obviously smaller than that of the frame angle method, the dynamic drift process of the platform in the swinging process can be visually observed, and the overall dynamic drift process of the platform can be controlled. The invention can realize the base transposition of the inertia platform by using the position swing platform, and can essentially solve the problem of over-tolerance in the direction locking and swinging of the platform.
Those skilled in the art will appreciate that the details of the invention not described in detail in this specification are well within the skill of those in the art.
Claims (9)
1. A method for testing the swing dynamic precision of an inertial platform based on gravity vector measurement is characterized by comprising the following steps:
(1) setting a swing test environment;
(2) carrying out a swing test of the inertia platform in a vertical state;
(3) carrying out a swing test of the inertia platform in a horizontal state, which specifically comprises the following steps: after the swing test of the inertia platform in a vertical state is finished, rotating the inner ring of the swing platform by 90 degrees to enable the inertia platform to be horizontally converted to carry out the swing test of the inertia platform in a horizontal state, firstly carrying out a static drift test of the inertia platform, then continuously carrying out two times of dynamic drift tests of the inertia platform in a swing state, and finally carrying out a static drift test of the inertia platform again; the method specifically comprises the following steps:
(3.1) returning the swing platform to the initial position, wherein the inner ring is 90 degrees, the middle ring is 0 degree, and the outer ring is 0 degree;
(3.2) sending an indexing command of any position by the inertial platform to enable attitude angles of X, Y and Z axes to be 0 degree;
(3.3) after waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second;
(3.4) starting the static drift test of the inertial platform, keeping the swing table still, and sending an index command of any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(3.5) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second; starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(3.6) repeating the step (3.5) and testing the dynamic drift of the inertial platform once;
(3.7) repeating the step (3.4) and testing the static drift of the inertial platform once;
(4) calculating the gravity vector output of the inertial platform in a space stable state;
(5) performing attitude calculation on the inertial platform based on the gravity vector output;
(6) and calculating the swing drift rate of the inertial platform in a fixed window value taking mode.
2. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 1, wherein: the swing test environment is set, and the method specifically comprises the following steps: selecting a position swing table to carry out a swing test, placing an inertial platform on the position swing table, electrifying the inertial platform after the inertial platform is installed, and stabilizing the inertial platform according to the requirement of the precision stabilization time of a gyroscope and a quartz accelerometer; the inner ring, the middle ring and the outer ring of the swing table are arranged according to swing test conditions, and the swing test conditions comprise: three rings are arranged to swing according to sine wave with the same frequency and amplitude, and the phase difference between two adjacent shafts is the same.
3. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 2, wherein: the frequency value is set to 1Hz, the amplitude is set to 6 +/-0.5 degrees, and the phase difference between two adjacent axes is not more than 45 degrees.
4. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 2, wherein: the position swing platform is provided with three rotating rings, namely an inner ring, a middle ring and an outer ring, which can rotate continuously for 360 degrees, and controls the transposition and swing of each ring through a control system comprising a photoelectric encoder and a shaft end motor.
5. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 1, wherein: performing a swing test of the inertia platform in a vertical state, firstly performing a static drift test of the inertia platform, then continuously performing two dynamic drift tests of the inertia platform in a swing state, and finally performing a static drift test of the inertia platform; the method specifically comprises the following steps:
(2.1) returning the swing platform to zero, and sending an indexing command of any position by the inertial platform to enable attitude angles of X, Y and Z axes to be 0 degree;
(2.2) after waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second;
(2.3) starting the static drift test of the inertial platform, keeping the swing table still, and sending an index command of any position after the inertial platform waits for 600 seconds to enable attitude angles of X, Y and Z axes to return to 0 degree;
(2.4) carrying out dynamic drift test on the inertial platform, waiting for 180 seconds, switching the inertial platform into a quartz accelerometer flight navigation state, and taking the moment as a time zero point, namely 0 second; starting the swing platform to swing after 90 seconds, and stopping the swing platform after 570 seconds; after 600 seconds, the inertial platform sends an indexing command of any position to enable attitude angles of X, Y and Z axes to return to 0 degree again;
(2.5) repeating the step (2.4) and testing the dynamic drift of the inertial platform once;
and (2.6) repeating the step (2.3) and testing the static drift of the inertial platform once.
6. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 1, wherein: the step (4) of calculating the gravity vector output of the inertial platform in the space stable state specifically comprises the following steps:
(4.1) after the vertical state swing test, respectively acquiring four groups of quartz accelerometer data of the inertial platform in two horizontal directions, and acquiring four groups of quartz accelerometer data of the inertial platform in the other direction after the horizontal state swing test;
(4.2) carrying out low-pass filtering on the quartz accelerometer data in three directions, and then calculating the original specific force output of the quartz accelerometer
Wherein:
and
respectively representing pulse output of a positive channel and a negative channel of the quartz accelerometer, delta t is the time interval of the pulse output, K 0j1.25g And K 1j1.25g Representing zero-order terms and first-order terms of the quartz accelerometer, and j representing the axial directions of three inertial platforms of x, y and z;
and (4.3) sorting the specific force output of the quartz accelerometer in the x direction, the y direction and the z direction to obtain a gravity vector measurement result of the inertial platform in a space stable state.
7. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 6, wherein: the step (5) of performing attitude calculation on the inertial platform based on the gravity vector output specifically comprises:
(5.1) carrying out inertial platform installation error compensation on the specific force output of the quartz accelerometer, and solving the specific force output f of the quartz accelerometer on the inertial platform coordinate system after the installation error of the compensation system p ：
Wherein the content of the first and second substances,
and (3) representing a mounting error compensation matrix of the quartz accelerometer in an inertial platform coordinate system:
Q xz 、Q xy respectively representing the included angles Q between the X-axis quartz accelerometer and the Z axis and the Y axis of the coordinate system of the inertial platform yz 、Q yx Respectively representing the included angles Q between the Y-axis quartz accelerometer and the Z axis and the X axis of the coordinate system of the inertial platform zy 、Q zx Respectively representing the included angles between the Z-axis quartz accelerometer and the Y-axis and the X-axis of the inertial platform coordinate system;
(5.2) let d x 、d y And d z Representing the angle of the platform drift about the inertial platform coordinate system X, Y and the Z-axis respectively,
the drift angles of the inertial platform in the horizontal axis direction corresponding to different states of the base are as follows:
8. the method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement as claimed in claim 7, wherein: the step (6) calculates the swing drift rate of the inertial platform by means of fixed window value taking, and specifically comprises the following steps:
(6.1) drawing the drift angle curves of the three axes of the inertia platform obtained by resolving to obtain an attitude drift curve of the whole swing drift process of the inertia platform;
(6.2) according to the drift curve, carrying out value calculation after the quartz accelerometer of the inertial platform body deviates from the leveling position and is stably output, and determining initial t for calculating the platform drift angular velocity 0 Time value, and t after the end of oscillation 1 And (3) calculating the moment value, and then calculating the swaying drift angular velocity for each section of flight navigation curve fixed window value totaling T seconds, namely the static or dynamic drift angular velocity is as follows:
representing the x, y and z platform axis directions.
9. The method for testing the swinging dynamic accuracy of the inertial platform based on the gravity vector measurement of claim 8, wherein the method comprises the following steps: calculating the swing drift rate of the inertial platform, namely calculating the difference between the two times of dynamic drift angular velocities and the average value of the two times of static drift angular velocities:
in the formula: omega r1 The first dynamic drift angular velocity; omega r2 Angular velocity for the second dynamic drift; omega s1 Angular velocity for the first static drift; omega s2 The angular velocity of the second static drift.
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