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IMU: What Is an Inertial Measurement Unit?

Do you dream of being an aircraft operator? What about designing or engineering UAVs?

An IMU is not something that you’ll use in your everyday life (unless you’re in a very specific profession), but it’s still something that you should understand if you care about angular rates and velocity.

What do you know about IMUs? If you don’t know much, keep reading because we are going to give you insights into what these letters mean and what you need to know.

What Is an IMU?

An IMU, which stands for Inertial Measurement Unit, is a type of electronic device with inertial capabilities that helps measure and report data. The specific data targeted with these devices include acceleration, angular rates, gravitational forces, and orientation.

These devices have 3 accelerometers, 3 magnetometers (typically), and 3 gyroscopes. This means there are 6 Degrees of Freedom (DoF).

All of these components are crucial to the device, as there is one of each per axes (roll, yaw, and pitch).

The Three Types of IMU Sensors

Each IMU sensor exists to help lower the overall costs and power requirements while also ensuring high levels of performance from the device. However, they are different in how they function, and you can find IMUs with variations depending on the make and model.

The three sensor options in an IMU include:

  • Fiber optic gyroscope (detects changes in position or direction)
  • Ring laser gyroscope (maintains orientation)
  • Microelectromechanical system (MEMS) gyroscopes

MEMS are important here because they help the small unit be more powerful while also drawing less actual power. Fiber optic gyroscopes are typically more cost-effective.

IMU vs. AHRS  vs. INS

While these three things do have a lot in common, they are not interchangeable terms.

The main function of an IMU is to combine the functions of the accelerometers and gyroscopes.

An AHRS will use the magnetometer as well more readily in order to find the heading angle and magnetic north. Full pitch, roll angles, and yaw can also be calculated this way with AHRS. It is a sort of motion sensor first and foremost.

An INS, which stands for Inertial Navigation System, will help with accuracy when compared to an IMU. IMUs that are low-cost will have drifting issues, but INS provides fused navigation information with GNSS, including velocity and altitude, with free integration.

Start Using an IMU Today

While an IMU may seem like a technologically complicated device, it actually isn’t.

It all comes down to basic math by looking at linear acceleration rate and rotational rate. This information is important for aircrafts, UAVs, and many other major systems that we use in our society today.

If you’re a science nut, learning more about IMUs can be a helpful way to understand our world better.

Did you like this article? If so, be sure to take a look at the rest of our blog for more fascinating information like this.

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