What is IMU Sensor and How to use with Arduino?

IMU, meaning for Inertial Measurement Unit is defined as a 9-axis sensor that measures orientation, velocity, and gravitational forces by combining Accelerometer, Gyroscope, and Magnetometer into one. IMUs typically come in large packages, but with recent developments like MEMS technology, they are now more commonly seen as miniaturized sensors designed for easy integration with Arduino or other microcontrollers.

As such, I’ll be introducing the list of IMU sensors available at Seeed, and how you can use it with an Arduino. But before that, let’s understand more about IMUs!

  • If you’re looking for a buying guide on Accelerometer and Gyroscope sensor, do refer to my previous post here!

How does IMU work?

IMU Sensor Working Principle

We established in the introduction that IMUs measures orientation, velocity, and gravitational forces but how does it work to achieve that?

IMUs work by detecting rotational movement of the three-axis, commonly known as Pitch, Roll, and YAW. To achieve such, it relies on the functionality of Accelerometers, Gyroscopes, and Magnetometer.

Accelerometers

  • Accelerometers serve as the tool for velocity measurement on an IMU since we know its functionality is to detect the rate of change in velocity of an object
  • Can only measure pitch and roll, no information about yaw

Gyroscopes

  • Gyroscopes serve as the tool for rotation/rotational rate measurement on an IMU since we know its functionality is to detect rotational changes or maintaining orientation

Magnetometer

  • Magnetometer serves as the tool for gravitational force measurement on an IMU
  • Compared to Accelerometer that can’t measure yaw since it works on a constant gravitational force, a magnetometer is a great compliment for accelerometer sensors

Combining these three sensors gives u a 9dof IMU that measures orientation, velocity, and gravitational force. A common model of such sensors is the InvenSense MPU-9250!

What is the use of IMU sensor?

Key Applications of IMU

IMUs are most commonly used in Inertial Navigations Systems to control aircraft, ships, submarines, and other unmanned aerial vehicles. However, with its wide measurement capabilities, IMUs are still applicable for other usages as follow:

  • Consumer electronics; Smartphones, tablets, fitness trackers for motion sensing and orientation
  • GPS and satellite positioning systems
  • Sports technology and training applications
  • Personal transportation devices like Segway for stabilization/balancing of vehicle

The above is a general list of IMU applications but so long as motion detection is required, IMU can be used.

Disadvantages of IMUs

As much as IMUs are picked for many applications, it’s still not an error-free option for motion sensing needs. Accumulated error, also known as “drift” is the main disadvantage of IMUs, present due to its constant measuring of changes and rounding off its calculated values off. When such a process happens for a prolonged period of time, it can lead to significant errors.

With no way improving the accuracy of an IMU aside from using better inertial sensors, we’ve gathered to recommend a few IMU sensor options that are worth taking a look!

Recommended IMU Sensors at Seeed

Here at Seeed, we have a couple of IMU sensors for you to choose from, ranging from 9DoF to 10Dof option. All applicable for microcontroller usage and Grove Compatible!

Grove Compatible?

Grove system is Seeed very own initiative, mainly aimed at helping users like yourself to easily use different modules, sensors, and more through our plug and play system!

  • We currently already hold more than 200 Grove modules, including other sensor types for you to choose from!

As compared to the other IMU 9DOF breakout boards offered, ours require no breadboard, jumper wires, and circuit building for pairing with Arduino!

Don’t believe how easy pairing is made possible with Grove? Below shows a general IMU sensor vs one of our Grove – IMU 9DOF Sensor:

Like how simple and less messy it is?

All you need is a Grove Base Shield alongside your Arduino and you’re good to go!

  • We’ll talk more about the IMU sensor pairing guide afterwards

Now let’s move on to our recommendations!

MPU-9250 option: Grove – IMU 9DOF v2.0

Starting off the list of IMU sensors here at Seeed is this 9DOF IMU sensor module! It’s an affordably priced and low powered module that delivers high performance!

Packed with a 3-axis gyroscope, a 3-axis accelerometer, and a 3-axis magnetometer, it’s a 9-axis motion tracking module based on MPU-9250.

Its features include:

  • Ultra-low power, low voltage
  • Wide Detecting Range
  • Internal Digital Motion Processing™ (DMP™) engine supports advanced MotionProcessing and low power functions such as gesture recognition using programmable interrupts
  • Self-test function
  • Digital-output 3-Axis angular rate sensors (gyroscopes) with a user-programmable full-scale range of ±250, ±500, ±1000, and ±2000°/sec
  • Digital-output 3-Axis accelerometer with a programmable full-scale range of ±2g, ±4g, ±8g, and ±16g
  • Digital-output 3-Axis accelerometer with a full-scale measurement range is ±4800μT

Interested to find out more about the Grove – IMU 9DOF v2.0? You can head to our product page here!

BMP280 with MPU-9250: Grove – IMU 10DOF v2.0

Need a substantial upgrade from the previous recommendation? The Grove – IMU 10DOF v2.0 provides a total of 10 axes of data for you, way more applications, better performance!

Based on the newly released BMP280, this IMU sensor module is only 65% smaller than the BMP180, but consumes way lesser power; only 2.7uA@1Hz!

  • For more information on the MPU-9250 and BMP280, do refer to the respective datasheets attached

Its features include:

  • Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable full-scale range of ±250, ±500, ±1000, and ±2000°/sec
  • Digital-output 3-Axis accelerometer with a programmable full-scale range of ±2g, ±4g, ±8g, and ±16g
  • Digital-output magnetometer with a full-scale range of ±4800uT
  • Temperature measurement with ±1.0°C accuracy
  • Barometric pressure measurement range 300 – 1100 hPa with ±1.0 hPa accuracy

Interested to find out more about the Grove – IMU 10DOF v2.0? You can head out to our product page here!

How to use IMU sensor with Arduino?

We’ve recommended our IMU sensor modules for your selection but wonder how can you use them with Arduino? Here’s a simple tutorial to help you get started. We’ll be using the Grove – IMU 10DOF v2.0 as our IMU sensor!

Here’s what you need:

  • Seeeduino is Seeed’s very own Arduino board, built with relative benefits over the original
    • If you do not wish to purchase a Seeeduino, this tutorial is still applicable for the following Arduino boards: Arduino UNO, Arduino Mega, Arduino Leonardo, Arduino 101, Arduino Due

How to connect:

  • Step 1: Connect Grove – IMU 10DOF v2.0 to I2C port of the Grove – Base Shield
  • Step 2: Plug Grove – Base Shield into Seeeduino
  • Step 3: Connect Seeeduino to PC via a USB cable

Software configurations and Arduino Code:

  • Step 4: Upload the code. Note that we should select the correct board type and COM port. Where we can see:

Summary

That’s all for today’s guide on IMU sensors and modules for Arduino usage. I hope with this, you get a better understanding of what is an IMU Sensor, how it works, and the modules available for Arduino usage!

Start creating your very own motion-sensing project with our list of IMU sensor modules today!

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