#include <diff_drive_controller.h>

Inheritance diagram for diff_drive_controller::DiffDriveController:

Classes
struct	Commands
	Velocity command related: More...
Public Member Functions
	DiffDriveController ()
bool	init (hardware_interface::VelocityJointInterface *hw, ros::NodeHandle &root_nh, ros::NodeHandle &controller_nh)
	Initialize controller.
void	starting (const ros::Time &time)
	Starts controller.
void	stopping (const ros::Time &time)
	Stops controller.
void	update (const ros::Time &time, const ros::Duration &period)
	Updates controller, i.e. computes the odometry and sets the new velocity commands.
Private Member Functions
void	brake ()
	Brakes the wheels, i.e. sets the velocity to 0.
void	cmdVelCallback (const geometry_msgs::Twist &command)
	Velocity command callback.
bool	getWheelNames (ros::NodeHandle &controller_nh, const std::string &wheel_param, std::vector< std::string > &wheel_names)
	Get the wheel names from a wheel param.
bool	setOdomParamsFromUrdf (ros::NodeHandle &root_nh, const std::string &left_wheel_name, const std::string &right_wheel_name)
	Sets odometry parameters from the URDF, i.e. the wheel radius and separation.
void	setOdomPubFields (ros::NodeHandle &root_nh, ros::NodeHandle &controller_nh)
	Sets the odometry publishing fields.
Private Attributes
std::string	base_frame_id_
	Frame to use for the robot base:
double	cmd_vel_timeout_
	Timeout to consider cmd_vel commands old:
realtime_tools::RealtimeBuffer < Commands >	command_
Commands	command_struct_
bool	enable_odom_tf_
	Whether to publish odometry to tf or not:
Commands	last_cmd_
ros::Time	last_state_publish_time_
std::vector < hardware_interface::JointHandle >	left_wheel_joints_
	Hardware handles:
SpeedLimiter	limiter_ang_
SpeedLimiter	limiter_lin_
std::string	name_
geometry_msgs::TransformStamped	odom_frame_
boost::shared_ptr < realtime_tools::RealtimePublisher < nav_msgs::Odometry > >	odom_pub_
	Odometry related:
Odometry	odometry_
ros::Duration	publish_period_
	Publish rate related:
std::vector < hardware_interface::JointHandle >	right_wheel_joints_
ros::Subscriber	sub_command_
boost::shared_ptr < realtime_tools::RealtimePublisher < tf::tfMessage > >	tf_odom_pub_
size_t	wheel_joints_size_
	Number of wheel joints:
double	wheel_radius_
	Wheel radius (assuming it's the same for the left and right wheels):
double	wheel_radius_multiplier_
double	wheel_separation_
	Wheel separation, wrt the midpoint of the wheel width:
double	wheel_separation_multiplier_
	Wheel separation and radius calibration multipliers:

Detailed Description

This class makes some assumptions on the model of the robot:

the rotation axes of wheels are collinear
the wheels are identical in radius Additional assumptions to not duplicate information readily available in the URDF:
the wheels have the same parent frame
a wheel collision geometry is a cylinder in the urdf
a wheel joint frame center's vertical projection on the floor must lie within the contact patch

Definition at line 63 of file diff_drive_controller.h.

Constructor & Destructor Documentation

diff_drive_controller::DiffDriveController::DiffDriveController ( )

Definition at line 108 of file diff_drive_controller.cpp.

Member Function Documentation

void diff_drive_controller::DiffDriveController::brake ( ) [private]

Brakes the wheels, i.e. sets the velocity to 0.

Definition at line 328 of file diff_drive_controller.cpp.

void diff_drive_controller::DiffDriveController::cmdVelCallback ( const geometry_msgs::Twist & command ) [private]

Velocity command callback.

Parameters:

command Velocity command message (twist)

Definition at line 338 of file diff_drive_controller.cpp.

bool diff_drive_controller::DiffDriveController::getWheelNames	(	ros::NodeHandle &	controller_nh,
		const std::string &	wheel_param,
		std::vector< std::string > &	wheel_names
	)		`[private]`

Get the wheel names from a wheel param.

Parameters:

[in]	controller_nh	Controller node handler
[in]	wheel_param	Param name
[out]	wheel_names	Vector with the whel names

Returns:: true if the wheel_param is available and the wheel_names are retrieved successfully from the param server; false otherwise

Definition at line 358 of file diff_drive_controller.cpp.

bool diff_drive_controller::DiffDriveController::init	(	hardware_interface::VelocityJointInterface *	hw,
		ros::NodeHandle &	root_nh,
		ros::NodeHandle &	controller_nh
	)		`[virtual]`

Initialize controller.

Parameters:

hw	Velocity joint interface for the wheels
root_nh	Node handle at root namespace
controller_nh	Node handle inside the controller namespace

Reimplemented from controller_interface::Controller< hardware_interface::VelocityJointInterface >.

Definition at line 121 of file diff_drive_controller.cpp.

bool diff_drive_controller::DiffDriveController::setOdomParamsFromUrdf	(	ros::NodeHandle &	root_nh,
		const std::string &	left_wheel_name,
		const std::string &	right_wheel_name
	)		`[private]`