Application

# How to Qualitatively Evaluate the Dynamic Accuracy of IMU?

What is the heading angle drift phenomenon?

The heading angle drift of the 6-axis module is inevitable, but the degree is different. The device determines the performance, and the algorithm is not omnipotent. It should be noted that all attitude modules need to be powered on for about 1s to obtain the zero offset of the gyro, otherwise the heading angle drift will be more serious.

The 9-axis module needs to be configured in 9-axis mode, and the geomagnetism has been calibrated, and a stable and drift-free heading angle can be output in an environment without geomagnetic space distortion interference. In indoor environments: around desks, factories, laboratories, next to instruments and equipment The magnetic field distortion in the regional space is very serious. In the 9-axis mode, the heading angle north pointing accuracy is generally poor. For the first time, you can test the performance of the module outdoors and compare it indoors.

Without professional equipment such as turntables, how to easily and quickly evaluate dynamic accuracy qualitatively?

(This is a qualitative analysis, and quantitative results cannot be given): A simple qualitative analysis method: place the module horizontally, pick up the module after stabilization and perform random maneuvering motion (move slowly, not too violently, do not exceed the gyro range), move After a certain period of time (2-5min), it will return to the horizontal position. At this time, it will be found that the pitch and roll angles have a “back to positive” process. This is because the accelerometer in motion is no longer only the gravity vector, so it cannot provide an absolute reference for the pitch and roll angle, and can only rely on the gyro integral to recursively deduce the attitude. With the passage of time, the pure gyro integral attitude will inevitably have errors. After being placed horizontally again, the module is in a static state, and the accelerometer measures only the gravity vector, so it can continue to provide an absolute reference for the pitch and roll angle, so there is a “return to positive” process. Therefore, the gyro performance of this product can be simply and qualitatively compared from the magnitude of “back to positive” (rather than speed). The greater the return to positive range, the greater the accumulated error of the gyro during the movement.

In addition, it is difficult to see this process of “returning to alignment” with the naked eye only by looking at the pitch and roll values. It must be observed with the help of the upper computer using a curve or a visual instrument panel.

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