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What is an IMU?

High Precision Three Axis MEMS Gyro

The full name of IMU is the inertial measurement unit, which consists of three single-axis accelerometers and three single-axis gyroscopes. The accelerometer detects the acceleration signal of the object in the independent three-axis of the carrier coordinate system, and the gyroscope detects the carrier relative to the angular velocity signal of the navigation coordinate system, after processing these signals, the attitude of the object can be calculated.

In a narrow sense, an IMU installs a gyroscope and an accelerometer on three orthogonal axes, with a total of 6 degrees of freedom, to measure the angular velocity and acceleration of an object in three-dimensional space, which is what we know as “6-axis IMU”;

In a broad sense, the IMU can add a magnetometer to the accelerometer and gyroscope to form the “9-axis IMU” that is now known to the public.

The accelerometer detects the acceleration signal of the object in the independent three-axis of the carrier coordinate system, and the gyroscope detects the angular velocity signal of the carrier relative to the navigation coordinate system, measures the angular velocity and acceleration of the object in the three-dimensional space, and calculates the attitude of the object. The core value of the IMU in navigation is irreplaceable, and to improve its reliability, each single axis can be equipped with a wider variety of sensors. In order to ensure the measurement accuracy, the general IMU should be installed on the center of gravity of the measured object.

In fact, don’t look at the IMU technology that looks relatively unfamiliar. In fact, the mobile phones we use every day, the cars, airplanes, and even missiles and spaceships that we use when we travel all use IMU. The difference lies in cost and accuracy. According to different usage scenarios, there are different requirements for the accuracy of the IMU. High accuracy also means high cost.

Low-precision IMU: Used in ordinary consumer electronic products, this low-precision IMU is very cheap, and is widely used in mobile phones and sports watches, and is often used to record the number of walking steps.

Medium-precision IMU: used in unmanned driving, the price ranges from a few hundred yuan to tens of thousands of yuan, depending on the positioning accuracy requirements of the driverless car.

High-precision IMU: applied to missiles or space shuttles. Take the missile as an example, from the launch of the missile to the target, the aerospace-grade IMU can achieve extremely high-precision calculations, and the error can even be less than one meter.

In addition to the characteristics of accuracy and cost, IMU has two very key characteristics. The first is high update frequency, and the operating frequency can reach more than 100Hz; the second is high calculation accuracy in a short period of time without too much error. .

In order to make the IMU obtain higher accuracy, on the basis of three accelerometers and three gyroscopes, many manufacturers will also add magnetometers, and in order to improve reliability, some will increase the number of sensors.

Main parameters and characteristics of ERICCO’s IMU ER-MIMU-02

What is an IMU

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