IMU (Inertial Measurement Unit) is an inertial measurement unit that can measure the three-axis acceleration and angular velocity of an object. It is generally used in the measurement part of the system to estimate the pose of the object. IMU generally includes a three-axis accelerometer and a three-axis gyroscope. The accelerometer detects the acceleration signal of the object on three independent axes of the carrier coordinate system, and the gyroscope detects the angular velocity signal of the carrier relative to the navigation coordinate system. The angular velocity and acceleration in space can solve the pose of the object. MEMS IMU is cheap and small, and is widely used in many fields such as navigation, drones, VR, robots, and smart bracelets. The detection accuracy of the IMU is very important to the overall performance of the system. If the noise detected by the IMU is very noisy, then the feedback the system gets is wrong, just like human eyes, ears and other sense organs get wrong information. How can we move freely? The bottom layer of the system is the foundation. If the bottom layer of the system is unstable, it will be difficult for the upper layer to function well. ERICCO has always strictly controlled the accuracy of IMU and has been pursuing the improvement of IMU system. Next, ERICCO will also launch new high-precision IMU products.
1. Zero bias temperature hysteresis characteristics
The zero-bias temperature hysteresis characteristic means that the corresponding zero-bias of the IMU is inconsistent during the heating phase and the cooling phase. Some IMU data manuals will give the zero-bias temperature hysteresis characteristic curve, and some will not. It is best to test it when applying the IMU. Since the IMU zero bias estimate is calibrated based on temperature (the IMU calibration algorithm is introduced in detail), if the temperature lag difference is not too large, the calibration accuracy will be relatively high; if the IMU zero bias hysteresis value is too large, the IMU zero calibration error will be relatively high. large, thus affecting the fusion effect.
2.Vibration characteristics
In the case of external vibration, the variation characteristics of IMU deviation with vibration frequency. Some MEMS IMU chips have abnormal frequency characteristics under high-frequency excitation. For applications such as rotor drones that are prone to high-frequency vibrations, vibration characteristics are generally tested. If the IMU frequency characteristics are abnormal, you can consider it. Add shock absorbers.
3. Effect of repeated power-on on IMU deviation
Ideally, it is thought that under the same external conditions, the bias of the IMU will remain the same each time it is powered up. In fact, under the same external conditions, the bias of the IMU will be different every time the IMU is powered up. If the difference is relatively large, it will be zero. The bias estimation error will be relatively large, affecting the fusion effect.
4. The impact of stress on prejudice
The influence of stress on IMU includes: the influence of stress moment on offset, and the influence of different stresses on offset. The stress mainly comes from: the stress exerted by the PCB board on the IMU chip and the stress exerted by the temperature control device on the IMU chip. If the IMU bias is too sensitive to the impact of stress, it will also affect the zero drift estimation error, thus affecting the fusion effect.
5. Impact of impact on zero deviation
When the IMU is subjected to an external impact (on the order of tens of G), it is possible that the IMU will get stuck or the deviation will change. In general, testing should be done.
6. Nonlinear factor (%Fs)
Ideally, we consider the sensor data to be linear over this range. In fact, the sensor changes are non-linear. As shown in Figure 2, the nonlinear characteristics of the IMU need to be tested before use. If the nonlinearity is too severe, nonlinear calibration should be performed. There are many such calibration methods, such as proportional calibration, quadratic fitting calibration, etc.
If you want to know more about IMU products, please click the link below
Web:https://www.ericcointernational.com/inertial-measurement-units
Email: info@ericcointernational.com
Whatsapp: 13630231561
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