A MEMS inertial instrument starting zero error compensation method

Abstract

The present application relates to a kind of MEMS inertial instrument start zero error compensation method, belong to inertial measurement field.The present application includes calibration test method, start zero error compensation model, parameter table format and parameter calculation method.Start zero error compensation model is designed as the function related to time, and the relationship with time is 3 order polynomial;7 temperature intervals are set simultaneously to obtain more accurate compensation parameters respectively to obtain compensation coefficient.The present application designs start zero error compensation model as time related, avoids the measurement of the complex temperature field in MEMS inertial instrument, can obtain more accurate compensation parameters;The output precision of inertial instrument is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of inertial measurement, and particularly relates to a MEMS inertial instrument startup zero error compensation method. BACKGROUND

[0002] The inertial measurement device is an important equipment on a missile, and provides angular velocity and acceleration information for a missile information processor, and is used for navigation, guidance and stable control. The inertial instrument, as a core component of the inertial measurement device, includes a gyroscope and an accelerometer, and is respectively used for measuring carrier angular velocity and acceleration information; a typical configuration is that three orthogonal sensitive axes (X axis, Y axis and Z axis) of the gyroscope and the accelerometer are orthogonal. The MEMS inertial instrument has obvious advantages in low-precision inertial instrument engineering applications in terms of low price, high reliability, low power consumption and small size. However, some MEMS inertial instruments have startup zero error, and the zero output value tends to be stable after about 5 minutes; the startup zero error affects the initial alignment, navigation and guidance error of a weapon system, and affects the missile hitting accuracy and rapid response capability.

[0003] The internal temperature field of the MEMS inertial instrument is complex and difficult to measure, and it is not convenient to use the traditional temperature modeling. In view of the repeatability of the zero curve of the MEMS inertial instrument, a time-dependent startup zero error compensation method is introduced, and the zero output stability of the MEMS inertial instrument is improved. SUMMARY

[0004] (I) Technical problem to be solved

[0005] The technical problem to be solved by the application is how to provide a MEMS inertial instrument startup zero error compensation method to solve the problem of inaccurate temperature field measurement in the conventional startup zero error compensation method.

[0006] (II) Technical scheme

[0007] In order to solve the above technical problem, the application provides a MEMS inertial instrument startup zero error compensation method, which comprises the following steps:

[0008] S1, according to the working range of the inertial measurement device -40℃~+60℃, 8 temperature points are selected: -40℃, -30℃, -20℃, -10℃, 0℃, 40℃, 50℃, 60℃, and constant temperature calibration tests are respectively carried out: after the first constant temperature time, the temperature value of the inertial instrument in the inertial measurement device at the power-on time is collected;

[0009] S2, divide the temperature into 7 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃, according to the inertial instrument temperature value collected when power on, reference temperature interval, determine the temperature compensation interval of the inertial instrument temperature value collected at the power-on time; so as to determine the compensation coefficient, start the zero error compensation model as follows:

[0010] Z i0 =B i0 +B i1 ×t+B i2 ×t 2 +B i3 ×t 3 (2)

[0011] Wherein, Z i0 : inertial instrument start-up zero error compensation value, the actual output value deducts the compensation value, which is the output after compensation; t: time after power on, unit: s; B i0 ~B i3 : the compensation coefficient in the i-th temperature interval;

[0012] S3, set the 7 temperature intervals and the zero error compensation coefficient of each interval to configuration items to form a parameter table, upload to the inertial measurement device data storage, the processor software reads the inertial instrument temperature value once when power on, and calculates the start-up zero error compensation value in real time according to the compensation model;

[0013] S4, the output of the inertial instrument is compensated and then deducted by the start-up zero error compensation value at the current time.

[0014] (Three) beneficial effects

[0015] The present application provides a MEMS inertial instrument start-up zero error compensation method, the present application provides a MEMS inertial instrument start-up zero error compensation method, the present application includes calibration test method, start-up zero error compensation model, parameter table format and parameter calculation method. The zero error compensation model is designed as a function related to time, and the relationship with time is a 3-order polynomial; at the same time, the temperature interval is roughly divided into 7 segments to obtain more accurate compensation parameters. The present application designs the start-up compensation model to be related to time, which avoids the measurement of the complex temperature field inside the MEMS inertial instrument, and can obtain more accurate compensation parameters; improve the output precision of the inertial instrument. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The working flow chart of the MEMS inertial instrument start-up zero error compensation method of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, content and advantages of the present application more clear, the specific embodiments of the present application are described in further detail below in combination with the drawings and examples.

[0018] The present application relates to a MEMS inertial instrument startup zero error compensation method, belonging to the field of inertial measurement. The present application includes calibration test method, startup zero error compensation model, parameter table format and parameter calculation method. The startup zero error compensation model is designed as a function related to time, and the relationship with time is a 3-order polynomial; at the same time, 7 temperature intervals are set to obtain compensation coefficients, so as to obtain more accurate compensation parameters. The present application designs the startup zero error compensation model to be related to time, avoids the measurement of the complex internal temperature field of the MEMS inertial instrument, and can obtain more accurate compensation parameters; and improves the output precision of the inertial instrument.

[0019] In order to solve the above technical problems, the present application provides a MEMS inertial instrument startup zero error compensation method, which comprises the following steps:

[0020] S1, according to the working range of the inertial measurement device -40℃ to +60℃, 8 temperature points are selected: -40℃, -30℃, -20℃, -10℃, 0℃, 40℃, 50℃, 60℃, and constant temperature calibration test is carried out respectively: after the first holding time, the temperature value at the power-on time of the inertial instrument in the inertial measurement device is collected; the first time is determined according to the internal temperature stability of the product, and in an embodiment, it is 1h.

[0021] S2, the temperature is divided into 7 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃, according to the temperature value of the inertial instrument collected at the power-on time, the temperature compensation interval of the temperature value of the inertial instrument collected at the power-on time is determined by referring to the temperature interval; so as to determine the compensation coefficient, and the startup zero error compensation model is as follows:

[0022] Z i0 =B i0 +B i1 ×t+B i2 ×t 2 +B i3 ×t 3 (2)

[0023] Wherein, Z i0 : the startup zero error compensation value of the inertial instrument, the actual output value minus the compensation value is the compensated output; t: time after power-on, unit: s; B i0 ~B i3 : the compensation coefficient in the i th temperature interval.

[0024] S3, set 7 temperature intervals and each interval start zero error compensation coefficient as configuration item formation parameter table, upload to inertial measurement device data storage, processor software reads once inertial instrument temperature value at power on, according to compensation model, carry out start zero error compensation value real-time solution.

[0025] S4, deduct start zero error compensation value after error compensation of inertial instrument output, then output at current time (0 time at power on). In case of meeting following any 1 condition, exit start zero error compensation, compensation value is constant 0:

[0026] 1) t >= T M , T M is maximum value of start time of multiple inertial instruments of this type;

[0027] 2) |Z i0 | is less than or equal to 0.01 after conversion into ° / h or mg unit.

[0028] Further, the step S1 specifically comprises the following steps:

[0029] S11, inertial measurement device is installed on calibration tooling, tooling is fixed on three-axis turntable with temperature box, XYZ axis initial position is south of the celestial equator, and the inertial measurement device comprises an inertial instrument;

[0030] S12, temperature box is set at constant temperature point, product is powered on for test after heat preservation time A, and data is collected;

[0031] S13, test time B.

[0032] Further, the time A is 1h.

[0033] Further, the time B is 5min.

[0034] Further, the step S2 specifically comprises the following steps:

[0035] S21, 1s smooth mean value of X axis, Y axis and Z axis output is obtained at each constant temperature point, and the output of the 1st second is deducted, namely, the start output curve at the constant temperature point is obtained;

[0036] S22, 7 interval segments: [-40, -30) ℃, [-30, -20) ℃, [-20, -10) ℃, [-10, 0) ℃, [0, 40) ℃, [40, 50) ℃, [50, 60] ℃, respectively, according to start output curve at 2 boundary constant temperature points in the interval, the start output curve mean value is obtained, and the 3-order polynomial coefficient B i0 ~ Bi3 ;

[0037] Further, the MEMS inertial instrument includes a gyroscope and an accelerometer.

[0038] Further, in the step S3, the data is uploaded to the data storage of the inertial measurement device according to a predetermined protocol format through the communication interface.

[0039] Embodiment 1:

[0040] The application designs a compensation method for start-up zero error of MEMS inertial instrument, including calibration test method, start-up zero error compensation model, parameter table format and parameter calculation method. The start-up zero error compensation model is designed as a function of start-up zero error compensation value and time, and the relationship with time is a 3-order polynomial. Meanwhile, 7 temperature intervals are set to calculate compensation coefficients, so as to obtain more accurate compensation parameters.

[0041] (I) Calibration method:

[0042] S1, according to the working range of the inertial measurement device -40℃~+60℃, 8 temperature points are selected: -40℃, -30℃, -20℃, -10℃, 0℃, 40℃, 50℃, 60℃, and constant temperature calibration test is carried out respectively: after 1h of heat preservation (the heat preservation time is determined according to the internal temperature stability of the product), the temperature value at the power-on moment of the inertial instrument in the inertial measurement device is collected.

[0043] S11, the inertial measurement device is installed on the calibration tool, the tool is fixed on the three-axis turntable with a temperature box, the initial position of XYZ axis is east of the South Pole, and the inertial measurement device includes an inertial instrument.

[0044] S12, the temperature box is set at a constant temperature point, and the product is powered on for test after 1h of heat preservation, and data is collected.

[0045] S13, test for 5min.

[0046] (II) Start-up zero error compensation model:

[0047] S2, divide the temperature into 7 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃, according to the temperature value of the inertial instrument collected at the power-on moment, reference the temperature interval, determine the temperature compensation interval where the current temperature is located; so as to determine the compensation coefficient, and the start-up zero error compensation model is as follows:

[0048] Z i0 =B i0 +B i1 ×t+B i1 ×t2 B i1 ×t 3 ......(3)

[0049] wherein, Z i0 : inertial instrument start-up zero error compensation value, actual output value minus the compensation value is the compensated output; t: time after power-up, B i0 ~B i3 : compensation coefficient in the ith temperature interval.

[0050] (Three) parameter table format:

[0051] S3, set 7 temperature intervals and temperature coefficients of each interval as configuration items to form a parameter table, upload to the inertial measurement device data storage through the communication interface according to the predetermined protocol format, and the processor software reads the current temperature value of the inertial instrument once in a predetermined time interval, and performs real-time calculation of zero compensation parameters according to the compensation model. Taking an axis inertial instrument as an example, the parameter table format is as follows:

[0052] Table 2 zero parameter table format

[0053]

[0054]

[0055] S4, after the inertial instrument output is compensated for error, the output is deducted by the start-up zero error compensation value at the current time (0 time when power-up). In the case of meeting any one of the following conditions, the start-up zero error compensation is exited, and the compensation value is constant 0:

[0056] a. t≥T M (T M is the maximum value of the start-up time of multiple inertial instruments of this type)

[0057] b. |Z i0 | converted into ° / h or mg unit is less than or equal to 0.01.

[0058] (Four), compensation coefficient calculation method:

[0059] Taking a gyroscope as an example:

[0060] S21, obtain the 1s smoothed output sequence of the X-axis, Y-axis and Z-axis power-up output values at each constant temperature point, and subtract the average of the output of the first second from each value in the sequence to obtain the zero error curve at the start-up temperature point.

[0061] S22. Divide the temperature into 6 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃. Based on the zero-point error curves at two constant temperature points within each interval, calculate the average values ​​at corresponding time points, and then fit a 3rd-order polynomial coefficient with time as the independent variable and the zero-point error compensation value as the dependent variable: B i0 ~B i3 .

[0062] Example 2:

[0063] A method for zero-position error compensation during startup of a MEMS inertial instrument, comprising the following steps:

[0064] S1. Based on the working range of the inertial measurement device (IMT) from -40℃ to +60℃, select 8 temperature points: -40℃, -30℃, -20℃, -10℃, 0℃, 40℃, 50℃, and 60℃, and perform constant temperature calibration tests on each point: after holding the temperature for 1 hour (the holding time depends on the internal temperature stability of the product), collect the temperature value of the inertial instrument in the IMT at the moment of power-on.

[0065] S2. Divide the temperature into 7 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃. Based on the temperature value collected by the inertial instrument upon power-on and referring to the temperature intervals, determine the temperature compensation interval for the current temperature; thereby determining the compensation coefficient and activating the zero-point error compensation model as follows:

[0066] Z i0 =B i0 +B i1 ×t+B i1 ×t 2 +B i1 ×t 3 (1)

[0067] Among them, Z i0 : Zero-point error compensation value for inertial instrument startup; the actual output value minus this compensation value is the compensated output; t: Time after power-on, unit: seconds; B i0 ~B i3 : Compensation coefficient for the i-th temperature range.

[0068] S3. Set the 7 temperature ranges and the zero-point error compensation coefficient of each range as configuration items to form a parameter table, upload it to the inertial measurement device data storage, and the processor software reads the temperature value of the inertial instrument once when powered on, and performs real-time calculation of the zero-point error compensation parameters according to the compensation model.

[0069] Furthermore, step S1 specifically includes the following steps:

[0070] S11. The inertial measurement device is installed on the calibration fixture, which is fixed on a three-axis turntable with a temperature chamber. The initial position of the XYZ axes is east-south. The inertial measurement device includes inertial instruments.

[0071] S12. The temperature chamber is set at a constant temperature point. After the temperature is maintained for a duration of A, the product is powered on for testing and data is collected.

[0072] S13, Test duration B.

[0073] Furthermore, duration A is 1 hour.

[0074] Furthermore, duration B is 5 minutes.

[0075] Furthermore, step S2 specifically includes the following steps:

[0076] S21. At each constant temperature point, calculate the smoothed average of the X-axis, Y-axis, and Z-axis outputs over 1 second. Subtract the output in the first second to obtain the start-up output curve at that temperature point.

[0077] S22. Divide the temperature into 7 intervals: [-40, -30)℃, [-30, -20)℃, [-20, -10)℃, [-10, 0)℃, [0, 40)℃, [40, 50)℃, [50, 60]℃. Based on the start-up output curves at two constant temperature points within each interval, calculate the mean of the start-up output curves and fit a third-order polynomial coefficient with time as the independent variable and zero bias as the dependent variable: B i0 ~B i3 ;

[0078] Furthermore, for the first and seventh temperature ranges, the two selected constant temperature points are -40℃ and -30℃, and 50℃ and 60℃, respectively.

[0079] Furthermore, MEMS inertial instruments include MEMS gyroscopes and MEMS accelerometers.

[0080] Furthermore, in step S3, the data is uploaded to the inertial measurement device's data storage via a communication interface according to a predetermined protocol format.

[0081] This invention proposes a method for zero-point error compensation during startup of MEMS inertial instruments. The invention includes a calibration test method, a startup zero-point error compensation model, a parameter table format, and a parameter calculation method. The zero-point error compensation model is designed as a time-dependent function, with a relationship to time as a third-order polynomial. Simultaneously, the temperature range is roughly divided into seven segments, and compensation coefficients are calculated for each segment to obtain more accurate compensation parameters. By designing the startup compensation model as time-dependent, this invention avoids measuring the complex internal temperature field of the MEMS inertial instrument, thus obtaining more accurate compensation parameters and improving the output accuracy of the inertial instrument.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for compensating for zero-position error during startup of a MEMS inertial instrument, characterized in that, The method includes the following steps: S1. Based on the working range of the inertial measurement device (IMT) from -40℃ to +60℃, select 8 temperature points: -40℃, -30℃, -20℃, -10℃, 0℃, 40℃, 50℃, and 60℃, and conduct constant temperature calibration tests at each point. After the first heat preservation time, collect the temperature value of the inertial instrument in the IMT at the moment of power-on. S2. Divide the temperature into 7 intervals: [-40] ， -30)℃, [-30 ， -20)℃, [-20 ， -10)℃, [-10)℃ ， 0)℃, [0, 40)℃, [40 ， 50)℃, [50 ， [60]℃, based on the inertial instrument temperature value collected at power-on and the reference temperature range, the temperature compensation range of the inertial instrument temperature value collected at power-on is determined; thus, the compensation coefficient is determined, and the zero-position error compensation model is activated as follows: （2） in, : Zero-position error compensation value for inertial instrument startup; the actual output value minus this compensation value is the compensated output; t: Time after power-on, unit: seconds; ~ : Compensation coefficient within the i-th temperature range; S3. Set the 7 temperature ranges and the zero-point error compensation coefficient of each range as configuration items to form a parameter table, upload it to the data storage of the inertial measurement device, and the processor software reads the temperature value of the inertial instrument once when powered on, and performs real-time calculation of the zero-point error compensation value according to the compensation model. S4. The output of the inertial instrument is after error compensation, and then the zero-position error compensation value at the current moment is deducted before output. in, Step S2 specifically includes the following steps: S21. Calculate the smoothed average of the X-axis, Y-axis and Z-axis outputs for 1 second at each constant temperature point. Subtract the output for the first second to obtain the start-up output curve at that constant temperature point. S22, divided into 7 intervals: [-40 ， -30)℃, [-30 ， -20)℃, [-20 ， -10)℃, [-10)℃ ， 0)℃, [0,40)℃, [40 ， 50)℃, [50 ， 60℃, based on the start-up output curves at two constant temperature points within the interval, the mean value of the start-up output curve is calculated, and the coefficients of a third-order polynomial with time as the independent variable and the inertial instrument start-up zero-position error compensation value as the dependent variable are fitted: ; Step S4 further includes: under any one of the following conditions, exiting the zero-position error compensation activation, with the compensation value always being 0: 1) t≥T M T M This represents the maximum startup time for multiple inertial instruments of this model. 2) After conversion to ° / h or mg units, it is less than or equal to 0.

01.

2. The MEMS inertial instrument startup zero-position error compensation method as described in claim 1, characterized in that, Step S1 specifically includes the following steps: S11. The inertial measurement device is installed on the calibration fixture, which is fixed on a three-axis turntable with a temperature chamber. The initial position of the XYZ axes is east-south. The inertial measurement device includes inertial instruments. S12. The temperature chamber is set at a constant temperature point. After the temperature is maintained for a duration of A, the product is powered on for testing and data is collected. S13, Test duration B.

3. The MEMS inertial instrument startup zero-position error compensation method as described in claim 2, characterized in that, Duration A is 1 hour.

4. The MEMS inertial instrument startup zero-position error compensation method as described in claim 2, characterized in that, Duration B is 5 minutes.

5. The MEMS inertial instrument startup zero-position error compensation method as described in claim 2, characterized in that, Inertial instruments include gyroscopes and accelerometers.

6. The MEMS inertial instrument startup zero-position error compensation method as described in claim 1, characterized in that, In step S22, the constant temperature point is the boundary constant temperature point.

7. The MEMS inertial instrument startup zero-position error compensation method as described in claim 1, characterized in that, In step S3, the data is uploaded to the inertial measurement device's data storage via a communication interface according to a predetermined protocol format.

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