A complementary filter for a 6 axis IMU using quaternions. More...

#include <filter.hpp>

Public Member Functions
	Filter ()
	Default Constructor. More...

	Filter (const num_t gyroFavoring)
	Constructor. More...

	Filter (const num_t gyroFavoring, const Quaternion &initialQ)
	Constructor. More...

	Filter (const Filter &other)=default
	Copy constructor.

Filter &	operator= (const Filter &other)=default
	Assignment operator.

	~Filter ()=default
	Destructor.

	Filter (Filter &&)=default
	Move constructor.

Filter &	operator= (Filter &&)=default
	Move assignment.

void	updateGyro (const Vector3D &gyro, const num_t time)
	Updates filter with gyro data. More...

void	updateAccel (const Vector3D &accel)
	Updates filter with accelerometer data. More...

void	update (const Vector3D &accel, const Vector3D &gyro, const num_t time)
	Updates filter with both gyro and accel data. More...

void	reset ()
	Resets quaternion to [1, 0, 0, 0], or facing towards position x direction.

Quaternion	getRotQ () const
	Gets rotation quaternion of the complementary filter. More...

num_t	getGyroFavoring () const
	Gets gyroscope favoring. More...

void	setRotQ (const Quaternion &q)
	Sets rotation quaternion for the filter. More...

void	setGyroFavoring (const num_t favoring)
	Sets gyro favoring. More...

Detailed Description

A complementary filter for a 6 axis IMU using quaternions.

Integrates the gyro measurements, then uses a small fraction of the gravity measurements (from the accelerometer) to correct the orientation given from the gyro measurements. The fraction is specified through the gyroFavoring parameter in the constructor.

The math and details are based on these lectures from Stanford:

Constructor & Destructor Documentation

◆ Filter() [1/3]

imunano33::Filter::Filter ( )

inline

Default Constructor.

Initializes intiial quaternion to [1, 0, 0, 0] (or facing towards +x direction) and gyro favoring to 0.98. See other constructors for more information about gyro favoring.

◆ Filter() [2/3]

imunano33::Filter::Filter ( const num_t gyroFavoring )

inline

Constructor.

Parameters

gyroFavoring Determines how much gravity should correct, in the range [0, 1]. 0 means that gravity should fully correct the error (does not mean that orientation is solely determined by gravity), and 1 means that gravity does not correct error at all.

Note: If gyroFavoring is less than 0 or greater than 1, it gets clamped to 0 or 1.; If favoring is too high (> 0.99), then there might be latency in gravity correction.

◆ Filter() [3/3]

imunano33::Filter::Filter	(	const num_t	gyroFavoring,
		const Quaternion &	initialQ
	)

inline

Constructor.

Parameters

gyroFavoring	Determines how much gravity should correct, in the range [0, 1]. 0 means that gravity should fully correct the error (does not mean that orientation is solely determined by gravity), and 1 means that gravity does not correct error at all.
initialQ	The initial rotation quaternion.

Note: If gyroFavoring is less than 0 or greater than 1, it gets clamped to 0 or 1.; If initialQ is unnormalized, then the method will normalize it. If initialQ is set to be zeroes, this will result in undefined behavior.; If favoring is too high (> 0.99), then there might be latency in gravity correction.

Member Function Documentation

◆ getGyroFavoring()

num_t imunano33::Filter::getGyroFavoring ( ) const

inline

Gets gyroscope favoring.

Returns: gyro favoring

◆ getRotQ()

Quaternion imunano33::Filter::getRotQ ( ) const

inline

Gets rotation quaternion of the complementary filter.

Returns: rotation quaternion

◆ setGyroFavoring()

void imunano33::Filter::setGyroFavoring ( const num_t favoring )

inline

Sets gyro favoring.

Parameters

favoring The new gyro favoring, in the range [0, 1]

Note: If favoring is less than 0 or greater than 1, it will be clamped to 0 or 1.

◆ setRotQ()

void imunano33::Filter::setRotQ ( const Quaternion & q )

inline

Sets rotation quaternion for the filter.

Parameters

q	The rotation quaternion

Note: If q is unnormalized, then this method will normalize it. If q is set to be zeros, this will result in undefined behavior.

◆ update()

void imunano33::Filter::update	(	const Vector3D &	accel,
		const Vector3D &	gyro,
		const num_t	time
	)

inline

Updates filter with both gyro and accel data.

If you plan on only using the gyroscope measurements, then pass in a zero vector for the acceleration, as accelerometer corrections will not be performed if the acceleration vector is zero.

Parameters

accel	Accelerometer reading, in <x, y, z>, where positive z is up (important for gravity corrections), and xy is translational motion. The note comes with more details specific to the Arduino Nano 33.
gyro	Gyroscope reading (in rad/s)
time	The time it took for the reading to happen (in s)

Note: With the opening of the USB port facing front and the Arduino's sensors facing up, the positive x axis is to the front, the positive y axis is to the left, and the positive z axis is to the top.

◆ updateAccel()

void imunano33::Filter::updateAccel ( const Vector3D & accel )

inline

Updates filter with accelerometer data.

Parameters

accel Accelerometer reading, in <x, y, z>, where positive z is up (important for gravity corrections), and xy is translational motion. The note comes with more details specific to the Arduino Nano 33.

Note: With the opening of the USB port facing front and the Arduino's sensors facing up, the positive x axis is to the front, the positive y axis is to the left, and the positive z axis is to the top.

◆ updateGyro()

void imunano33::Filter::updateGyro	(	const Vector3D &	gyro,
		const num_t	time
	)

inline

Updates filter with gyro data.

Parameters

gyro	Gyroscope reading (in rad/s)
time	The time it took for the reading to happen (in s)

Note: With the opening of the USB port facing front and the Arduino's sensors facing up, the positive x axis is to the front, the positive y axis is to the left, and the positive z axis is to the top.

The documentation for this class was generated from the following file:

/home/runner/work/imunano33/imunano33/include/imunano33/filter.hpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Filter() [1/3]

◆ Filter() [2/3]

◆ Filter() [3/3]

Member Function Documentation

◆ getGyroFavoring()

◆ getRotQ()

◆ setGyroFavoring()

◆ setRotQ()

◆ update()

◆ updateAccel()

◆ updateGyro()