Madgwick Filter

The MadgwickFilter implements the Madgwick algorithm for orientation estimation using an IMU. The algorithm is based on the paper An efficient orientation filter for inertial and inertial/magnetic sensor arrays by Sebastian Madgwick. It supports state / orientation estimation for both 6-axis IMUs as well as for 9-axis IMUs.

API Reference

Header File

Classes

class MadgwickFilter

Madgwick filter for IMU data Based on: https://x-io.co.uk/open-source-imu-and-ahrs-algorithms/ (now https://github.com/xioTechnologies/Fusion)

Public Functions

inline explicit MadgwickFilter(float beta = 0.1f)

Constructor.

Parameters:

beta – Filter gain

inline void update(float dt, float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz)

Update the filter with new data.

Note

Accelerometer values should be normalized

Note

Gyroscope values should be in rad/s

Note

Magnetometer values should be normalized

Note

If magnetometer values are not available (all 0), this function will fallback to using only accelerometer and gyroscope values

Parameters:

  • dt – Time step in seconds

  • ax – Accelerometer x value in g

  • ay – Accelerometer y value in g

  • az – Accelerometer z value in g

  • gx – Gyroscope x value in rad/s

  • gy – Gyroscope y value in rad/s

  • gz – Gyroscope z value in rad/s

  • mx – Magnetometer x value in uT

  • my – Magnetometer y value in uT

  • mz – Magnetometer z value in uT

inline void update(float dt, float ax, float ay, float az, float gx, float gy, float gz)

Update the filter with new data.

Note

Accelerometer values should be normalized

Note

Gyroscope values should be in rad/s

Parameters:

  • dt – Time step in seconds

  • ax – Accelerometer x value in g

  • ay – Accelerometer y value in g

  • az – Accelerometer z value in g

  • gx – Gyroscope x value in rad/s

  • gy – Gyroscope y value in rad/s

  • gz – Gyroscope z value in rad/s

inline void get_euler(float &pitch, float &roll, float &yaw) const

Get the current quaternion values as euler angles.

Note

Euler angles are in degrees

Parameters:

  • pitch – [out] Pitch angle in degrees

  • roll – [out] Roll angle in degrees

  • yaw – [out] Yaw angle in degrees