MEMS (Micro Electro Mechanical System) micro-mechanical inertial measurement unit calibration method

Abstract

The invention provides an MEMS (Micro Electro Mechanical System) micro-mechanical inertial measurement unit calibration method, which comprises the following seven steps of: S1, preparing a turntable calibration tool, and requiring the tool to be tightly jointed with a turntable base surface to ensure the accuracy of acquired data; s2, the product is fastened to the tool through M4 * 8 screws, and the base face of the product is required to be parallel to the base face of the tool and the base face of the rotary table; and S3, setting a temperature change program of the double-shaft turntable with the temperature control function, keeping the low temperature at-40 DEG C for 2 hours, electrifying and collecting in the whole process, collecting at-40 DEG C for 1 hour, heating to + 80 DEG C at the speed of 0.3 DEG C / min, and keeping for 1 hour. According to the MEMS IMU calibration method provided by the invention, through a wide-temperature-range, multi-position and multi-rate calibration strategy and a new error model, the calibration temperature interval of the embodiment is-40 DEG C to + 80 DEG C, the calibration precision of the MEMS IMU is remarkably improved, the output of the MEMS IMU in different environments is more accurate and reliable, and the calibration precision of the MEMS IMU is improved. And the output precision of the product can be ensured in different environments.

Description

Technical Field

[0001] The invention relates to the field of MEMS micromechanical gyroscope and inertial navigation, and in particular to a calibration method for a MEMS micromechanical inertial measurement unit. Background Art

[0002] During the production of MEMS micromechanical inertial measurement units (hereinafter referred to as IMUs), IMUs usually use static temperature calibration compensation and other methods during the calibration and compensation stage. The existing calibration method steps are as follows:

[0003] 1. Establish an error model: First, a mathematical model needs to be established to describe the error characteristics of MEMS inertial devices, which includes static error and dynamic error models.

[0004] 2. Calibrate error parameters: Determine the parameters of the error model through experimental testing, i.e. the calibration process, which may include testing in multiple locations and responses to different environmental conditions.

[0005] 3. Compensation algorithm development: Based on the calibration results, develop corresponding compensation algorithms to correct the errors of the equipment. This may involve hardware and software adjustments.

[0006] After the calibration is completed using the existing calibration method, the following problems need to be solved:

[0007] 1) As the technology of MEMS micromechanical gyroscopes is becoming more and more perfect, the temperature coverage area of ​​the existing calibration method cannot meet the use of products at certain specific temperatures. The IMU temperature calibration is to conduct full-time power-on data collection on a marble platform in a temperature test box, starting from a low temperature of -25°C and raising the temperature to a high temperature of +40°C at a constant temperature change rate. Due to the rapid development of micromechanical gyroscopes, this temperature range can no longer meet the requirements of IMUs working in certain specific environments;

[0008] 2) Existing calibration methods mostly use static temperature calibration or single-position single-rate data acquisition. The data output by the MEMS micromechanical gyroscope is single, and the compensation parameters are not accurate enough, which directly affects the performance of the gyroscope itself. The calibration method on the market is single-position acquisition. The calibration parameters (zero position, scale factor, etc.) generated by data processing of the collected data are not accurate enough, which directly affects the real-time output of the gyroscope after being burned into the product.

[0009] Therefore, a calibration method of MEMS micromechanical inertial measurement unit was proposed. Summary of the invention

[0010] The present invention aims to solve the problem raised in the background technology and provides a MEMS micromechanical inertial measurement unit calibration method.

[0011] The specific technical solutions are as follows:

[0012] A method for calibrating a MEMS micromechanical inertial measurement unit comprises the following steps:

[0013] S1: Prepare the turntable calibration tooling, which includes a dual-axis turntable with temperature control. The tooling is required to fit the turntable base surface tightly to ensure the accuracy of the collected data;

[0014] S2: Fasten the product to the fixture with M4*8 screws. The base surface of the product must be parallel to the base surface of the fixture and the base surface of the turntable.

[0015] S3: Set a temperature change program with a temperature-controlled dual-axis turntable. Keep the low temperature at -40℃ for 2 hours and then power on for full data collection. After collecting at -40℃ for 1 hour, increase the temperature to +80℃ at 0.3℃ / min and keep it for 1 hour.

[0016] S4: Position and rate calibration is required in calibration compensation. In each temperature range, each axis faces east and west respectively. After the turntable middle frame axis rotates 180 degrees, it faces west and east again. Each axis performs zero bias calibration position. The rate point is the angular rate input from the turntable to each axis of the gyroscope, which is ±1° / S, ±10° / S, ±50° / S, and ±100° / S.

[0017] S5: Collect data using NV-IMU software;

[0018] S6: After the acquisition is completed, the data of multiple TXT documents are obtained, and the acquired data are fitted into the required calibration parameters and images using the MATLAB processing program;

[0019] S7: Burn the calibration parameters into the product, and the calibration is now complete.

[0020] The above-mentioned MEMS micromechanical inertial measurement unit calibration method, wherein: the specific scheme for judging the effect of the product after calibration is as follows:

[0021] Repeat steps S1 to S4 once, and use MATLAB to process the data after obtaining it. Check the processed results and judge the effect of the product after calibration based on the nonlinearity of the scale factor and the zero position index.

[0022] The above-mentioned MEMS micromechanical inertial measurement unit calibration method, wherein: the products include MSMS micromechanical gyroscopes and inertial navigation products.

[0023] The above-mentioned MEMS micromechanical inertial measurement unit calibration method, wherein: step S2 specifically comprises: using M4*8 screws to fasten the product to the tooling.

[0024] The above-mentioned MEMS micromechanical inertial measurement unit calibration method, wherein: the rate points are specifically set to eight, namely -150° / S, -100° / S, -50° / S, -10° / S, 10° / S, 50° / S, 100° / S, and 150° / S.

[0025] The above-mentioned MEMS micromechanical inertial measurement unit calibration method, wherein: the gyro error model in the MSMS micromechanical gyro and inertial navigation product is as follows:

[0026]

[0027] N gx N gy N gz The number of gyro output pulses, unit: LSB / s;

[0028] D fx D fy D fz Gyro constant drift, unit LSB / s;

[0029] S gx S gy S gz Gyro scale factor, unit LSB / ° / s;

[0030] K gij is the installation error coefficient of the i-axis to the j-gyro, in LSB / ° / s;

[0031] D ix D ax D sx D iy D oy D sy D iz D oz D sz Coefficient related to g, unit: ° / s / g.

[0032] The present invention has the following beneficial effects:

[0033] The MEMS micromechanical inertial measurement unit calibration method provided by the present invention has the following beneficial effects:

[0034] (1) Improve calibration accuracy: Through the wide temperature range, multi-position, multi-rate calibration strategy and the new error model, the calibration temperature range of this embodiment is -40°C to +80°C, which significantly improves the calibration accuracy of the MEMSIMU, making its output more accurate and reliable in different environments, and can ensure the output accuracy of the product in different environments.

[0035] (2) Enhanced environmental adaptability: The expanded calibration temperature range enables the IMU to cope with a wider range of working environment temperature changes, improving the environmental adaptability and reliability of the product.

[0036] (3) Improve calibration efficiency: The multi-position and multi-rate calibration method reduces the number of repetitions and time cost required for single-position and single-rate calibration, thereby ensuring accuracy while improving calibration efficiency.

[0037] (4) Promoting technological development: The present embodiment provides new ideas and methods for the calibration technology of MEMSIMU, and promotes the development and progress of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a MEMS micromechanical inertial measurement unit calibration method provided by an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the structure of the turntable calibration tool in the MEMS micromechanical inertial measurement unit calibration method provided in the embodiment of the present invention Figure 1 ;

[0040] Figure 3 Schematic diagram of the structure of the turntable calibration tool in the MEMS micromechanical inertial measurement unit calibration method provided in the embodiment of the present invention Figure 2 ;

[0041] Figure 4 Schematic diagram of the structure of the turntable calibration tool in the MEMS micromechanical inertial measurement unit calibration method provided in the embodiment of the present invention Figure 3 ;

[0042] Figure 5 Schematic diagram of the structure of the turntable calibration tool in the MEMS micromechanical inertial measurement unit calibration method provided in the embodiment of the present invention Figure 4 ;

[0043] Figure 6 Schematic diagram of the structure of the turntable calibration tool in the MEMS micromechanical inertial measurement unit calibration method provided in the embodiment of the present invention Figure 5 . DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0045] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0046] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0047] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Example

[0049] The MEMS micromechanical inertial measurement unit calibration method provided in this embodiment is as follows: Figure 1-Figure 6 As shown, including: including the following steps:

[0050] S1: Prepare the turntable calibration tooling, which is required to fit the turntable base surface tightly to ensure the accuracy of the collected data. The turntable calibration tooling includes a dual-axis turntable with temperature control;

[0051] S2: Fasten the product to the fixture with M4*8 screws. The base surface of the product must be parallel to the base surface of the fixture and the base surface of the turntable.

[0052] S3: Set a temperature change program with a temperature-controlled dual-axis turntable. Keep the low temperature at -40℃ for 2 hours and then power on for full data collection. After collecting at -40℃ for 1 hour, increase the temperature to +80℃ at 0.3℃ / min and keep it for 1 hour.

[0053] S4: Position and rate calibration is required in calibration compensation. In each temperature range, each axis faces east and west respectively. After the turntable middle frame axis rotates 180 degrees, it faces west and east again. Each axis performs zero bias calibration position. The rate point is the angular rate input from the turntable to each axis of the gyroscope, which is ±1° / S, ±10° / S, ±50° / S, and ±100° / S.

[0054] S5: Collect data using NV-IMU software;

[0055] S6: After the acquisition is completed, the data of multiple TXT documents are obtained, and the acquired data are fitted into the required calibration parameters and images using the MATLAB processing program;

[0056] S7: Burn the calibration parameters into the product, and the calibration is now complete.

[0057] Specifically, in this embodiment: the specific scheme for judging the effect of the product after calibration is as follows:

[0058] Repeat steps S1 to S4 once, and use MATLAB to process the data after obtaining it. Check the processed results and judge the effect of the product after calibration based on the nonlinearity of the scale factor and the zero position index.

[0059] Specifically, in this embodiment: the products include MSMS micromechanical gyroscopes and inertial navigation products.

[0060] Specifically, in this embodiment: step S2 specifically includes: using M4*8 screws to fasten the product to the tooling.

[0061] Specifically, in this embodiment: the rate points are specifically set to eight, namely -150° / S, -100° / S, -50° / S, -10° / S, 10° / S, 50° / S, 100° / S, and 150° / S.

[0062] Specifically, in this embodiment: the gyro error model in the MSMS micromechanical gyro and inertial navigation product is as follows:

[0063]

[0064] N gx N gy N gz The number of gyro output pulses, unit: LSB / s;

[0065] D fx D fy D fz Gyro constant drift, unit LSB / s;

[0066] S gx S gy S gz Gyro scale factor, unit LSB / ° / s;

[0067] K gij is the installation error coefficient of the i-axis to the j-gyro, in LSB / ° / s;

[0068] D ix D ax D sx Diy D oy D sy D iz D oz D sz Coefficient related to g, unit: ° / s / g.

[0069] In summary, this embodiment mainly adopts the following technical solutions:

[0070] (1) Wide temperature range calibration: This embodiment expands the calibration temperature range to -40°C to +80°C to cover a wider range of working environments. Through a dual-axis turntable with temperature control, a temperature change program is set to keep the IMU at a low temperature of -40°C for 2 hours and then start to collect data with full power. Then, the temperature is raised to a high temperature of +80°C at a constant rate of 0.3°C / min, and each temperature point is maintained for a certain period of time to ensure temperature stability and accuracy of data collection.

[0071] (2) Multi-position calibration: In view of the shortcomings of the traditional calibration method in collecting data at a single position, this embodiment adopts a multi-position calibration strategy. In each temperature range, each axis of the IMU is calibrated towards the east and west respectively, and the calibration position is increased by rotating the frame axis of the turntable (such as 180 degrees), so as to more comprehensively evaluate the performance of the IMU in different directions.

[0072] (3) Multi-rate calibration: In order to more accurately obtain the parameters such as the scale factor of the IMU, this embodiment sets multiple rate points during the calibration process. Different angular rates (such as ±1° / S, ±10° / S, ±50° / S, ±100° / S) are input to each axis of the gyroscope through the turntable to obtain output data at different rates to comprehensively evaluate the rate response characteristics of the IMU.

[0073] (4) Error model and data processing: This embodiment establishes a new error model to better describe and compensate for the various errors generated by the IMU during the calibration process. After the acquisition is completed, the NV-IMU software is used to save the data as multiple TXT documents, and the collected data is fitted and analyzed by data processing software such as MATLAB to generate the required calibration parameters and images. These parameters include but are not limited to zero position, scale factor, nonlinearity, etc., which are used for subsequent product calibration and performance evaluation.

[0074] (5) Calibration parameter burning and verification: The generated calibration parameters are burned into the MEMSIMU product to complete the calibration process. In order to verify the calibration effect, this embodiment also proposes a repeated calibration and verification step. That is, steps 1 to 4 are repeated once, new data is obtained and processed and analyzed, and the stability and reliability of the calibration effect are evaluated by comparing the results after the two calibrations (such as the nonlinearity of the scale factor, zero position and other indicators).

[0075] In summary, the MEMS micromechanical inertial measurement unit calibration method provided in this embodiment has the following advantages:

[0076] (1) Improve calibration accuracy: Through the wide temperature range, multi-position, multi-rate calibration strategy and the new error model, the calibration temperature range of this embodiment is -40°C to +80°C, which significantly improves the calibration accuracy of the MEMSIMU, making its output more accurate and reliable in different environments, and can ensure the output accuracy of the product in different environments.

[0077] (2) Enhanced environmental adaptability: The expanded calibration temperature range enables the IMU to cope with a wider range of working environment temperature changes, improving the environmental adaptability and reliability of the product.

[0078] (3) Improve calibration efficiency: The multi-position and multi-rate calibration method reduces the number of repetitions and time cost required for single-position and single-rate calibration, thereby ensuring accuracy while improving calibration efficiency.

[0079] (4) Promoting technological development: The present embodiment provides new ideas and methods for the calibration technology of MEMSIMU, and promotes the development and progress of related technologies.

[0080] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calibrating a MEMS micromechanical inertial measurement unit, characterized in that: The following steps are involved: S1: Prepare the turntable calibration tooling, which includes a dual-axis turntable with temperature control. The tooling is required to fit the turntable base surface tightly to ensure the accuracy of the collected data; S2: Fasten the product to the tooling, requiring the base surface of the product to be parallel to the base surface of the tooling and the base surface of the turntable; S3: Set a temperature change program with a temperature-controlled dual-axis turntable. Keep the low temperature at -40℃ for 2 hours and then power on for full data collection. After collecting at -40℃ for 1 hour, increase the temperature to +80℃ at 0.3℃ / min and keep it for 1 hour. S4: Position and rate calibration is required in calibration compensation. In each temperature range, each axis faces east and west respectively. After the turntable middle frame axis rotates 180 degrees, it faces west and east again. Each axis performs zero bias calibration position. The rate point is the angular rate input from the turntable to each axis of the gyroscope, which is ±1° / S, ±10° / S, ±50° / S, and ±100° / S. S5: Collect data using NV-IMU software; S6: After the acquisition is completed, the data of multiple TXT documents are obtained, and the acquired data are fitted into the required calibration parameters and images using the MATLAB processing program; S7: Burn the calibration parameters into the product, and the calibration is now complete.

2. The MEMS micromechanical inertial measurement unit calibration method according to claim 1, characterized in that: The specific scheme for judging the effect of the product after calibration is as follows: Repeat steps S1 to S4 once, and use MATLAB to process the data after obtaining it. Check the processed results and judge the effect of the product after calibration based on the nonlinearity of the scale factor and the zero position index.

3. The MEMS micromechanical inertial measurement unit calibration method according to claim 1, characterized in that: The products include MSMS micromechanical gyroscopes and inertial navigation products.

4. The MEMS micromechanical inertial measurement unit calibration method according to claim 1, characterized in that: Step S2 specifically includes: using M4*8 screws to fasten the product to the tooling.

5. The MEMS micromechanical inertial measurement unit calibration method according to claim 1, characterized in that: The rate points are specifically set to eight, namely -150° / S, -100° / S, -50° / S, -10° / S, 10° / S, 50° / S, 100° / S, and 150° / S.

6. The MEMS micromechanical inertial measurement unit calibration method according to claim 3, characterized in that: The gyro error model in the MSMS micromechanical gyro and inertial navigation product is as follows: N gx N gv ·N gz The number of gyro output pulses, unit: LSB / s; D fx D fy D fz Gyro constant drift, unit LSB / s; S gx S gv S gz Gyro scale factor, unit LSB / ° / s; K gij is the installation error coefficient of the i-axis to the j-gyro, in LSB / ° / s; D ix D ax D sx D iy D oy D sy D iz D oz D sz Coefficient related to g, unit: ° / s / g.

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