High-precision calibration method of accelerometer

Abstract

According to the high-precision calibration method of the accelerometer, through testing 12 different overturning positions of the accelerometer, output data of an X axis, a Y axis and a Z axis in different directions are comprehensively collected, the scale factor and the installation error of the accelerometer can be accurately calculated, the calibration precision of the accelerometer in various directions is improved, and meanwhile, the calibration accuracy of the accelerometer in various directions is improved. By controlling the temperature change of the incubator, the parameters of the accelerometer under different temperature conditions are tested, and more comprehensive high-precision calibration is realized by combining the influence of the temperature on the scale factor and the installation error.

Description

Technical Field

[0001] The invention relates to an accelerometer measurement method, and in particular to a high-precision calibration method for an accelerometer. Background Art

[0002] Accelerometer is a commonly used inertial sensor, widely used in navigation, control system and other fields. The performance and accuracy of the accelerometer directly affect the measurement accuracy of the entire system. Therefore, before using the accelerometer, it is usually necessary to calibrate it. The traditional accelerometer calibration method usually measures the output data under static acceleration conditions and calculates the scale factor based on the known value of the earth's gravity acceleration. However, the accelerometer is affected by environmental factors such as the installation location and temperature changes. The traditional method is difficult to fully reflect its performance under actual working conditions, resulting in insufficient measurement accuracy.

[0003] The calibration method of traditional accelerometers mainly relies on static or limited flip tests. Its flip states are few and not comprehensive enough, and it is impossible to calculate the nonlinear error of the accelerometer under different installation directions. At the same time, the impact of temperature on the performance of the accelerometer is not effectively considered, resulting in large deviations in the measurement accuracy of the accelerometer under different temperature environments. Summary of the invention

[0004] In order to solve the defect of the above-mentioned prior art that the accelerometer calibration method is insufficient in accuracy and causes a large measurement deviation of the accelerometer, the present invention provides a high-precision calibration method for the accelerometer.

[0005] The technical solution of the present invention is: a high-precision calibration method for an accelerometer, comprising the following steps:

[0006] S1: Install the accelerometer on a turntable with a temperature box, and use the temperature box to keep the ambient temperature of the accelerometer at a certain temperature point;

[0007] S2: Design a calibration position arrangement scheme for the accelerometer, and use a turntable to flip the accelerometer 12 times. The 12 flip position states of the accelerometer's three axes include:

[0008] First flip: the accelerometer X axis points to the sky, the accelerometer Y axis points to the east, and the accelerometer Z axis points to the north;

[0009] Second flip: the accelerometer X-axis points to the sky, the accelerometer Y-axis points to the west, and the accelerometer Z-axis points to the south;

[0010] The third flip: the accelerometer X-axis points to the ground, the accelerometer Y-axis points to the east, and the accelerometer Z-axis points to the south;

[0011] The fourth flip: the accelerometer X axis points to the ground, the accelerometer Y axis points to the west, and the accelerometer Z axis points to the north;

[0012] The fifth flip: the accelerometer X-axis points to the north, the accelerometer Y-axis points to the sky, and the accelerometer Z-axis points to the east;

[0013] The sixth flip: the accelerometer X-axis points to the south, the accelerometer Y-axis points to the sky, and the accelerometer Z-axis points to the west;

[0014] The seventh flip: the accelerometer X-axis points to the north, the accelerometer Y-axis points to the ground, and the accelerometer Z-axis points to the west;

[0015] The eighth flip: the accelerometer X-axis points to the south, the accelerometer Y-axis points to the ground, and the accelerometer Z-axis points to the east;

[0016] The ninth flip: the accelerometer X-axis points to the east, the accelerometer Y-axis points to the north, and the accelerometer Z-axis points to the sky;

[0017] The tenth flip: the accelerometer X-axis points to the west, the accelerometer Y-axis points to the south, and the accelerometer Z-axis points to the sky;

[0018] Eleventh flip: the accelerometer X-axis points to the west, the accelerometer Y-axis points to the north, and the accelerometer Z-axis points to the ground;

[0019] Twelfth flip: the accelerometer X-axis points to the east, the accelerometer Y-axis points to the south, and the accelerometer Z-axis points to the ground;

[0020] S3: Complete data collection according to step S2. After each flip of the accelerometer, the three-axis output data of the accelerometer collected by the acquisition circuit is used to calculate the scale factor of the three axes of the accelerometer. The calculation formula is as follows:

[0021]

[0022] Among them, K x is the x-axis scale factor, N x1 ~N x4 This is the output data of the first to fourth flipping of the x-axis;

[0023]

[0024] Among them, K y is the scale factor of the y-axis, N y5 ~N y8 The output data of the fifth to eighth flipping of the y-axis;

[0025]

[0026] Among them, K z is the scale factor of the z-axis, N z9 ~N z12 The acceleration output data for the ninth to twelfth times on the z-axis;

[0027] S4: According to the scale factors of the three axes of the accelerometer calculated in step S3 and the output data of the three axes of the accelerometer collected by the acquisition circuit, the installation errors of the three axes of the accelerometer are calculated. The calculation formula is as follows:

[0028]

[0029] Among them, E yx is the installation error of the y-axis, N y1 ~N y4 This is the output data of the first to fourth flipping of the y-axis;

[0030]

[0031] Among them, E zx is the installation error of the z-axis, N z1 ~N z4 It is the output data of the first to fourth flipping of the Z axis;

[0032]

[0033] Among them, E xy is the installation error of the X-axis, N x5 ~N x8 The output data of the fifth to eighth flipping of the x-axis;

[0034]

[0035] Among them, E zy is the installation error of the z-axis, N z5 ~N z8 It is the output data of the fifth to eighth flipping of the Z axis;

[0036]

[0037] Among them, E xz is the installation error of the X-axis, N x9 ~N x12 The output data of the ninth to twelfth flip of the x-axis;

[0038]

[0039] Among them, E yz is the installation error of the y-axis, N y9 ~N y12 The output data of the ninth to twelfth flip of the y-axis;

[0040] S5: Changing the ambient temperature of the accelerometer by controlling the temperature box, and repeating steps S2 to S4 to obtain the scale factors and installation errors of the three axes of the accelerometer at different temperatures.

[0041] Further, the acquisition circuit in steps S3 and S4 includes an I / F conversion circuit, a temperature detector and a power supply;

[0042] The I / F conversion circuit collects the measurement data of the accelerometer and transmits the measurement data to the CPLD;

[0043] The temperature detector detects the ambient temperature of the accelerometer and sends the temperature data to the terminal;

[0044] The power supply is used to supply power to the I / F conversion circuit, the temperature detector, the CPLD and the terminal.

[0045] The beneficial effects of the present invention are as follows: by testing 12 different flip positions of the accelerometer, the output data of the X-axis, Y-axis and Z-axis in different directions are comprehensively collected, the scale factor and installation error of the accelerometer can be accurately calculated, and the calibration accuracy of the accelerometer in various directions is increased. At the same time, by controlling the temperature change of the incubator, the parameters of the accelerometer under different temperature conditions are tested, and the influence of temperature on the scale factor and installation error is combined to achieve a more comprehensive and high-precision calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of the present invention;

[0047] Figure 2 This is the structure diagram of the acquisition circuit. DETAILED DESCRIPTION

[0048] In order to better understand the concept of the present invention, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0049] The technical solution of the present invention is as follows: A high-precision calibration method for an accelerometer, such as Figure 1 The steps shown include:

[0050] S1: Install the accelerometer on a turntable with a temperature box, and use the temperature box to keep the ambient temperature of the accelerometer at a certain temperature point;

[0051] S2: Design a calibration position arrangement scheme for the accelerometer, and use a turntable to flip the accelerometer 12 times. The 12 flip position states of the accelerometer's three axes include:

[0052] First flip: the accelerometer X axis points to the sky, the accelerometer Y axis points to the east, and the accelerometer Z axis points to the north;

[0053] Second flip: the accelerometer X-axis points to the sky, the accelerometer Y-axis points to the west, and the accelerometer Z-axis points to the south;

[0054] The third flip: the accelerometer X-axis points to the ground, the accelerometer Y-axis points to the east, and the accelerometer Z-axis points to the south;

[0055] The fourth flip: the accelerometer X axis points to the ground, the accelerometer Y axis points to the west, and the accelerometer Z axis points to the north;

[0056] The fifth flip: the accelerometer X-axis points to the north, the accelerometer Y-axis points to the sky, and the accelerometer Z-axis points to the east;

[0057] The sixth flip: the accelerometer X-axis points to the south, the accelerometer Y-axis points to the sky, and the accelerometer Z-axis points to the west;

[0058] The seventh flip: the accelerometer X-axis points to the north, the accelerometer Y-axis points to the ground, and the accelerometer Z-axis points to the west;

[0059] The eighth flip: the accelerometer X-axis points to the south, the accelerometer Y-axis points to the ground, and the accelerometer Z-axis points to the east;

[0060] The ninth flip: the accelerometer X-axis points to the east, the accelerometer Y-axis points to the north, and the accelerometer Z-axis points to the sky;

[0061] The tenth flip: the accelerometer X-axis points to the west, the accelerometer Y-axis points to the south, and the accelerometer Z-axis points to the sky;

[0062] Eleventh flip: the accelerometer X-axis points to the west, the accelerometer Y-axis points to the north, and the accelerometer Z-axis points to the ground;

[0063] Twelfth flip: the accelerometer X-axis points to the east, the accelerometer Y-axis points to the south, and the accelerometer Z-axis points to the ground;

[0064] S3: Complete data collection according to step S2. After each flip of the accelerometer, the three-axis output data of the accelerometer collected by the acquisition circuit is used to calculate the scale factor of the three axes of the accelerometer. The calculation formula is as follows:

[0065]

[0066] Among them, K x is the x-axis scale factor, N x1 ~N x4 This is the output data of the first to fourth flipping of the x-axis;

[0067]

[0068] Among them, K y is the scale factor of the y-axis, N y5 ~N y8 The output data of the fifth to eighth flipping of the y-axis;

[0069]

[0070] Among them, K z is the scale factor of the z-axis, N z9 ~N z12 The acceleration output data for the ninth to twelfth times on the z-axis;

[0071] S4: According to the scale factors of the three axes of the accelerometer calculated in step S3 and the output data of the three axes of the accelerometer collected by the acquisition circuit, the installation errors of the three axes of the accelerometer are calculated. The calculation formula is as follows:

[0072]

[0073] Among them, E yx is the installation error of the y-axis, N y1 ~N y4 This is the output data of the y-axis from the first to the fourth flip. Due to the influence of the x-axis rotation on the y-axis, the y-axis may deviate, so the installation error of the y-axis is calculated by this formula;

[0074]

[0075] Among them, E zx is the installation error of the z-axis, N z1 ~N z4 This is the output data of the first to fourth flips of the Z axis. Due to the influence of the rotation of the x axis on the z axis, the z axis may deviate, so the installation error of the z axis is calculated by this formula;

[0076]

[0077] Among them, E xy is the installation error of the X-axis, N x5 ~N x8 This is the output data of the fifth to eighth flipping of the x-axis. Due to the influence of the y-axis rotation on the x-axis, the x-axis may deviate, so the installation error of the x-axis is calculated by this formula;

[0078]

[0079] Among them, E zy is the installation error of the z-axis, N z5 ~N z8 This is the output data of the fifth to eighth flipping of the Z axis. Due to the influence of the rotation of the y axis on the z axis, the z axis may deviate, so the installation error of the z axis is calculated by this formula;

[0080]

[0081] Among them, E xz is the installation error of the X-axis, N x9 ~Nx12 This is the output data of the ninth to twelfth flip of the x-axis. Due to the influence of the z-axis rotation on the x-axis, the x-axis may deviate, so the installation error of the x-axis is calculated by this formula;

[0082]

[0083] Among them, E yz is the installation error of the y-axis, N y9 ~N y12 This is the output data of the ninth to twelfth flip of the y-axis. Due to the influence of the z-axis rotation on the y-axis, the y-axis may deviate, so the installation error of the y-axis is calculated by this formula;

[0084] S5: Changing the ambient temperature of the accelerometer by controlling the temperature box, and repeating steps S2 to S4 to obtain the scale factors and installation errors of the three axes of the accelerometer at different temperatures.

[0085] The acquisition circuit in steps S3 and S4 is as follows: Figure 2 The shown embodiment includes an I / F conversion circuit, a temperature detector and a power supply;

[0086] The I / F conversion circuit collects the measurement data of the accelerometer and transmits the measurement data to the CPLD through the level conversion circuit. The principle is that the I / F conversion circuit converts the current transmitted by the accelerometer into a digital signal, and the voltage of the digital signal is reduced by the level conversion circuit and then transmitted to the CPLD. The CPLD processes the digital signal and outputs it to the terminal.

[0087] The temperature detector detects the ambient temperature of the accelerometer. The temperature detector sends the temperature data to the terminal through an analog-to-digital converter. The temperature detector is a PT1000 temperature measuring resistor.

[0088] After receiving the test data and temperature data, the terminal starts calibration, calculates the test data through the above steps, calculates the scale factor and installation error, and calibrates with the corresponding temperature points.

[0089] The power supply provides power to the I / F conversion circuit, temperature detector, CPLD, level conversion circuit, and analog-to-digital converter.

[0090] The turntable in step S1 is an inertial test incubator turntable, which can implement the accelerometer calibration position arrangement scheme.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A high-precision calibration method for an accelerometer, characterized in that: The steps include: S1: Install the accelerometer on a turntable with a temperature box, and use the temperature box to keep the ambient temperature of the accelerometer at a certain temperature point; S2: Design a calibration position arrangement for the accelerometer. Use a turntable to flip the accelerometer 12 times. The 12 flip positions of the accelerometer along the three axes include: First flip: the accelerometer X axis points to the sky, the accelerometer Y axis points to the east, and the accelerometer Z axis points to the north; Second flip: the accelerometer X axis points to the sky, the accelerometer Y axis points to the west, and the accelerometer Z axis points to the south; The third flip: the accelerometer X axis points to the ground, the accelerometer Y axis points to the east, and the accelerometer Z axis points to the south; Fourth flip: the accelerometer X axis points to the ground, the accelerometer Y axis points to the west, and the accelerometer Z axis points to the north; Fifth flip: the accelerometer X axis points to the north, the accelerometer Y axis points to the sky, and the accelerometer Z axis points to the east; The sixth flip: the accelerometer X axis points to the south, the accelerometer Y axis points to the sky, and the accelerometer Z axis points to the west; The seventh flip: the accelerometer X axis points to the north, the accelerometer Y axis points to the ground, and the accelerometer Z axis points to the west; The eighth flip: the accelerometer X axis points to the south, the accelerometer Y axis points to the ground, and the accelerometer Z axis points to the east; The ninth flip: the accelerometer X axis points to the east, the accelerometer Y axis points to the north, and the accelerometer Z axis points to the sky; The tenth flip: the accelerometer X axis points to the west, the accelerometer Y axis points to the south, and the accelerometer Z axis points to the sky; Eleventh flip: the accelerometer X axis points to the west, the accelerometer Y axis points to the north, and the accelerometer Z axis points to the ground; Twelfth flip: the accelerometer X axis points to the east, the accelerometer Y axis points to the south, and the accelerometer Z axis points to the ground; S3: Complete data acquisition according to step S2. After each flip of the accelerometer, the three-axis output data of the accelerometer is collected by the acquisition circuit to calculate the scale factor of the three axes of the accelerometer. The calculation formula is as follows: Among them, K x is the scale factor of the x-axis, N x1 ~N x4 This is the output data of the first to fourth flips of the x-axis; Among them, K y is the scale factor of the y-axis, N y5 ~N y8 The output data of the fifth to eighth flip of the y-axis; Among them, K z is the scale factor of the z-axis, N z9 ~N z12 The acceleration output data for the ninth to twelfth times on the z-axis; S4: Calculate the installation error of the three axes of the accelerometer based on the scale factors of the three axes of the accelerometer calculated in step S3 and the output data of the three axes of the accelerometer collected by the acquisition circuit. The calculation formula is as follows: Among them, E yx is the installation error of the y-axis, N y1 ~N y4 This is the output data of the first to fourth flips of the y-axis; Among them, E zx is the installation error of the z-axis, N z1 ~N z4 This is the output data of the first to fourth flips of the Z axis; Among them, E xy is the installation error of the X axis, N x5 ~N x8 The output data of the fifth to eighth flip of the x-axis; Among them, E zy is the installation error of the z-axis, N z5 ~N z8 This is the output data of the fifth to eighth flips of the Z axis; Among them, E xz is the installation error of the X axis, N x9 ~N x12 This is the output data of the ninth to twelfth flip of the x-axis; Among them, E yz is the installation error of the y-axis, N y9 ~N y12 The output data of the ninth to twelfth flip of the y-axis; S5: Changing the ambient temperature of the accelerometer by controlling the temperature box, and repeating steps S2 to S4 to obtain the scale factors and installation errors of the three axes of the accelerometer at different temperatures.

2. The high-precision calibration method for an accelerometer according to claim 1, characterized in that: The acquisition circuit in steps S3 and S4 includes an I / F conversion circuit, a temperature detector, and a power supply; The I / F conversion circuit collects the measurement data of the accelerometer and transmits the measurement data to the CPLD; The temperature detector detects the ambient temperature of the accelerometer and sends the temperature data to the terminal; The power supply is used to supply power to the I / F conversion circuit, the temperature detector, the CPLD and the terminal.

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