What is the Meaning of IMU or Inertial Measurement Unit?

Virtual Reality, VR, Immersive Technology & Simulated Environment

What is the Meaning of IMU or Inertial Measurement Unit?

Recently updated on May 26th, 2021 at 10:20 pm

What is the meaning of IMU? IMU stands for Inertial Measurement Unit. This is the main component in the inertial navigation systems which are used in aircraft, watercraft, spacecraft and even guided missiles. Now, the usage has been extended to other consumer applications such as motion capture system, gaming, VFX, screen rotation, gesture recognition and navigation. In a virtual reality system, sometimes it will be used inside the controller to perform the motion tracking, sensing and capturing capabilities. For example, the Sixense STEM VR motion controller.

How IMU Works?

Usually it looks like a small and tiny box. Due to its small size, it falls under the MEMS family. MEMS stands for Micro-Electro-Mechanical Systems or simply known as micro machines or micro systems technology. Below is how the IMU from PERCEPTION NEURON project looks like.

Perception Neuron IMU

See how small it is compared with the coffee seed. Although it is small, but it is able to contain the combination of accelerometer, gyroscope and magnetometer. The accelerometer is basically a motion sensor. It is used to measure linear acceleration or detect the current rate of acceleration.

Meanwhile, the gyroscope is basically a rotation sensor. It is used to measure angular velocity and detect changes in rotational attributes which are roll, pitch and yaw.

And lastly, the magnetometer is used to measure magnetic field strength. It is used to assist calibrate against orientation drift.

Most of the time, there will be 3-axis accelerometer, 3-axis gyroscope and 3-axis magnetometer inside the IMU. For this type of setting, normally we will call it as a 9-axis IMU. But if it does not contain the magnetometer, then it will be called as a 6-axis IMU.

This video from MotionNode below provides short and easy-to-understand video on how IMU works.

The data collected from the IMU’s sensors will allow the computer to track the controller or the device position. If the IMU is wireless, people will call it as WIMU.

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