# 9-Axis IMU LESSON 8: Using Gyros for Measuring Rotational Velocity and Angle

In this lesson we explore approximating the roll and pitch of our sensor using only the gyros. The advantage of gyros is that they are not susceptible to vibration as much as the acceleromters. In the video we show you how you can simply approximate roll and pitch from the data coming from the gyroscopes. Note that while the gyros do not have the noise problem seen in the accelerometers, we now have a new problem that the gyros are susceptible to long term drift. As you play with these devices what you end up seeing is you will need to combine the data from the accelerometers and the gyros in a clever way to take advantage of the long term stability of the accelerometers and the noise immunity of they gyros. In effect, you will want to apply a high pass filter to the gyro data, and a low pass filter to the acceleromters.

To follow along at home, you will need an Arduino Nano, and an Adafruit BNO055 Inertial Measurement Sensor. We suggest using identical hardware if you want to follow along as different sensors have very different characteristics, and things will work much better for you if we are using the same sensor

This is the code which we developed in the video to demonstrate these concepts.

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

# 9-Axis IMU LESSON 7: Understanding Low Pass Filters

In this project, we have shown how accelerometers can be used to approximate tilt. We showed in Lesson 6 how vibration can cause a problem with such a strategy, as the system will interpret vibration to be changes in tilt. A partial solution to this problem can be to program a low pass filter into the project. The video above introduces you to the concept of a low pass filter, and shows some simple examples of programming and using a low pass filter to reduce noise.

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

# 9-Axis IMU LESSON 6: Determine Tilt From 3-axis Accelerometer

This lesson shows you some of the simple math, that will allow you to approximate tilt angle from a three axis accelerometer. In this entire series of lessons, we are using the BNO055 9-axis sensor connected to an Arduino Nano. It is possible to approximate tilt along the x-axis and tilt along the y-axis. These could roughly be considered to be like the Euler Angles of Pitch and Roll. It should be noted that the approximations are reasonable for tilt angles less than 45 degrees. Also note, that in this simple demonstration, real acceleration will be interpreted as tilt, hence the system will incorrectly interpret motion as tilt. Because of this, this approach should not be used on things like drones or other moving systems. It is just for simple demonstration purposes.

The code developed in the video above is included below for your convenience.

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

# 9-Axis IMU LESSON 5: Calibrating the BNO055 9-axis Inertial Measurement Sensor

In this lesson we show you how to get a clean calibration on your BNO055 9-axis sensorIn the video below we take you through the coded needed to calibrate the sensor, and a simple technique to quickly get the system properly calibrated.

The code developed in this video will be used in future lessons, and is included below:

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

# 9-Axis IMU LESSON 4: Plotting Serial Data from Arduino with Control of Axis Scale

As this project continues it is very important for us to be able to quickly and easily plot data streaming from the sensor. The Arduino Serial Plotter has some real limitations, we recommend a simple “Serial Plotter” tool that can be downloaded. In this video we take you step by step through the download and installation process, and then an overview of how to use the tool.