An introduction to IMU (Inertial Measurement Unit)

Variense IMU VMU931
Variense VMU931

At this point you might be wondering “What’s an IMU?”.

Well, the answer can be as simple or as complex as you want it to be. In this article, I’m simply going to explain the purpose of such a device.

First of all, IMU stands for Inertial Measurement Unit. It’s a unit that measures… inertia.

Of course, that’s not very helpful if you don’t know what inertia is or what you can do with such measurements.

In simple terms, we use inertia to describe the motion of objects and how they are affected by applied forces.

IMUs might sound like some new technology out of the latest James Bond movie, but they’ve actually been used in multiple fields for quite some time now.

One of their first applications was in navigational systems for rockets, where inertia was used to track the rocket’s position and orientation. After that, IMUs went widespread with the rise of spacecraft, guided missiles, and commercial airliners.

imu roll pitch yaw
Principal axes of an aircraft

Here’s an example of the kind of information you get out of an IMU:

Imagine an airplane. It can rotate in three axes, which we call roll, pitch and yaw.

If we know the value of these three angles, we can safely say that we know the orientation of the airplane.

This is where the IMU comes into play, because the inertial measurement unit can be used to calculate the roll, pitch, and yaw – among other things – of any object, including an airplane.

Inertial measurement unit of an S3 Missile

In the 80’s, the inertial measurement systems used in missiles were quite large – about the size of a briefcase. Today, an IMU is an electronic chip smaller than a penny.

The compact size means we can now use IMUs in more creative ways. For example, motion capture applications, recreational remote-controlled drones, and augmented reality systems have all benefited from the latest innovations in inertial measurement.

But the size of these new IMUs isn’t the only thing that makes them one of the most popular pieces of technology. There’s also that timelessly important factor: price!

IMUs may once have been purchased only by militaries and government labs, but now they’re cheap enough for everybody to have one in their garage.

There are tons of online resources – RobotShop, Adafruit, SparkFun – that can help you learn how to use an IMU in your projects. And with the help of an Arduino or Raspberry Pi, you can accomplish things that would have seemed like science fiction 20 years ago.

So don’t hesitate to inform yourself about inertial measurement units – or get out there and start building something. You’ll be amazed by the potential of this technology.

And for the more tech-savvy among you, our next article titled What’s the Difference between MEMs and IMUs? gives you a closer look at the inner workings of our IMU (the VMU931).

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