mecanum_drive_controller::Odometry Class Reference

The Odometry class handles odometry readings (2D pose and velocity with related timestamp) More...

#include <odometry.hpp>

Public Types
typedef std::function< void(double, double, double)>	IntegrationFunction
	Integration function, used to integrate the odometry:

Public Member Functions
	Odometry ()
	Constructor Timestamp will get the current time value Value will be set to zero.
void	init (const rclcpp::Time &time, std::array< double, PLANAR_POINT_DIM > base_frame_offset)
	Initialize the odometry. More...
bool	update (const double wheel_front_left_vel, const double wheel_rear_left_vel, const double wheel_rear_right_vel, const double wheel_front_right_vel, const double dt)
	Updates the odometry class with latest wheels position. More...
double	getX () const
double	getY () const
double	getRz () const
double	getVx () const
double	getVy () const
double	getWz () const
void	setWheelsParams (const double sum_of_robot_center_projection_on_X_Y_axis, const double wheels_radius)
	Sets the wheels parameters: mecanum geometric param and radius. More...

Detailed Description

The Odometry class handles odometry readings (2D pose and velocity with related timestamp)

Member Function Documentation

getRz()

double mecanum_drive_controller::Odometry::getRz ( ) const

inline

Returns

orientation (z component) [m]

getVx()

double mecanum_drive_controller::Odometry::getVx ( ) const

inline

Returns

body velocity of the base frame (linear x component) [m/s]

getVy()

double mecanum_drive_controller::Odometry::getVy ( ) const

inline

Returns

body velocity of the base frame (linear y component) [m/s]

getWz()

double mecanum_drive_controller::Odometry::getWz ( ) const

inline

Returns

body velocity of the base frame (angular z component) [m/s]

getX()

double mecanum_drive_controller::Odometry::getX ( ) const

inline

Returns

position (x component) [m]

getY()

double mecanum_drive_controller::Odometry::getY ( ) const

inline

Returns

position (y component) [m]

init()

void mecanum_drive_controller::Odometry::init	(	const rclcpp::Time &	time,
		std::array< double, PLANAR_POINT_DIM >	base_frame_offset
	)

Initialize the odometry.

Parameters

time	Current time

setWheelsParams()

void mecanum_drive_controller::Odometry::setWheelsParams	(	const double	sum_of_robot_center_projection_on_X_Y_axis,
		const double	wheels_radius
	)

Sets the wheels parameters: mecanum geometric param and radius.

Parameters

sum_of_robot_center_projection_on_X_Y_axis	Wheels geometric param (used in mecanum wheels' ik) [m]
wheels_radius	Wheels radius [m]

update()

bool mecanum_drive_controller::Odometry::update	(	const double	wheel_front_left_vel,
		const double	wheel_rear_left_vel,
		const double	wheel_rear_right_vel,
		const double	wheel_front_right_vel,
		const double	dt
	)

Updates the odometry class with latest wheels position.

Parameters

wheel_front_left_vel	Wheel velocity [rad/s]
wheel_rear_left_vel	Wheel velocity [rad/s]
wheel_rear_right_vel	Wheel velocity [rad/s]
wheel_front_right_vel	Wheel velocity [rad/s]
time	Current time

Returns

true if the odometry is actually updated

We cannot estimate the speed with very small time intervals:

Compute FK (i.e. compute mobile robot's body twist out of its wheels velocities): NOTE: the mecanum IK gives the body speed at the center frame, we then offset this velocity at the base frame. NOTE: in the diff drive the velocity is filtered out, but we prefer to return it raw and let the user perform post-processing at will. We prefer this way of doing as filtering introduces delay (which makes it difficult to interpret and compare behavior curves).

Note

The variables meaning: angular_transformation_from_center_2_base: Rotation transformation matrix, to transform from center frame to base frame linear_transformation_from_center_2_base: offset/linear transformation matrix, to transform from center frame to base frame

Integration. NOTE: the position is expressed in the odometry frame , unlike the twist which is expressed in the body frame.

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

• ros2_controllers/mecanum_drive_controller/include/mecanum_drive_controller/odometry.hpp
• ros2_controllers/mecanum_drive_controller/src/odometry.cpp