Post by kellyyu on Jan 12, 2024 3:49:24 GMT -5
During gyroscope calibration, when the angular rate of the turntable is large, the rotation time is short, and the earth’s rotation angular rate is much greater than the drift amount of MEMS gyroscopes, so the drift of the gyroscope and the scale factor matrix can be calibrated separately. The common method is to install the gyroscope on the inner frame of the turntable, control the three axes of the turntable to rotate forward and reverse for n turns, set the unit time, collect the gyro angular rate output, and use the output pulse of the forward rotation of the gyro to the reverse rotation of the gyro. The output pulse is poor, weakening the influence of the earth’s rotation angular rate and the drift of the gyroscope itself. The turntable used for calibration is a three-axis turntable with a U-O-O shape. The three axes can rotate continuously 360°. MEMS gyroscope is installed on the inner frame and is installed as shown in Figure 4. During calibration, the outer frame continuously rotates. By controlling the middle frame and the inner frame, the calibration axis coincides with the axis of the outer frame in sequence.
Establish the geographical coordinate system o0x0y0z0, the outer frame axis coordinate system o1x1y1z1, the middle frame axis coordinate system o2x2y2z2, the inner frame axis coordinate system o3x3y3z3 and the MEMS gyro coordinate system OXYI on the three-axis turntable, where X represents the x-axis direction of the MEMS gyro, and Y represents the y-axis direction of the gyroscope, I represents the input axis direction of MEMS gyroscopes. In an ideal state, the three-axis coordinate systems are coincident, the rotation angle is zero, and the MEMS gyroscope is installed on the inner frame axis coordinate system. At the initial moment, the x-axis of the MEMS gyroscope is parallel to the middle frame axis, the y-axis is parallel to the inner frame axis, and the input axis I is parallel to the outer frame axis.
The specific calibration process of MEMS gyroscopes are as follows:
First, the turntable is energized and preheated. After the gyro connected to it runs for a certain time, the unit sampling time is set when the gyro output data is stable. The arrangement path of this calibration is to calibrate parameters by single-axis speed dual-axis position method. The outer frame of the turntable is used as the input axis, input a constant angular rate, the inner frame axis and the middle frame axis are in the angular position state, record the outer frame angular rate, the inner frame Angle position and the middle frame Angle position, and carry out two positive and negative rotation experiments to offset the influence of the earth rotation and the gyro’s own drift.
Figure 4 Schematic diagram of coordinate system
Establish the geographical coordinate system o0x0y0z0, the outer frame axis coordinate system o1x1y1z1, the middle frame axis coordinate system o2x2y2z2, the inner frame axis coordinate system o3x3y3z3 and the MEMS gyro coordinate system OXYI on the three-axis turntable, where X represents the x-axis direction of the MEMS gyro, and Y represents the y-axis direction of the gyroscope, I represents the input axis direction of MEMS gyroscopes. In an ideal state, the three-axis coordinate systems are coincident, the rotation angle is zero, and the MEMS gyroscope is installed on the inner frame axis coordinate system. At the initial moment, the x-axis of the MEMS gyroscope is parallel to the middle frame axis, the y-axis is parallel to the inner frame axis, and the input axis I is parallel to the outer frame axis.
The specific calibration process of MEMS gyroscopes are as follows:
First, the turntable is energized and preheated. After the gyro connected to it runs for a certain time, the unit sampling time is set when the gyro output data is stable. The arrangement path of this calibration is to calibrate parameters by single-axis speed dual-axis position method. The outer frame of the turntable is used as the input axis, input a constant angular rate, the inner frame axis and the middle frame axis are in the angular position state, record the outer frame angular rate, the inner frame Angle position and the middle frame Angle position, and carry out two positive and negative rotation experiments to offset the influence of the earth rotation and the gyro’s own drift.
Figure 4 Schematic diagram of coordinate system