#include <ackermann_controller.h>

Inheritance diagram for ackermann_controller::AckermannController:

Classes
struct	Commands
	Velocity command related: More...
Public Member Functions
	AckermannController ()
std::string	getHardwareInterfaceType () const
	Get the name of this controller's hardware interface type.
bool	init (hardware_interface::PositionJointInterface hw_pos, hardware_interface::VelocityJointInterface hw_vel, ros::NodeHandle &root_nh, ros::NodeHandle &controller_nh)
virtual bool	initRequest (hardware_interface::RobotHW *const robot_hw, ros::NodeHandle &root_nh, ros::NodeHandle &controller_nh, std::set< std::string > &claimed_resources)
	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	cmdAckermannCallback (const ackermann_msgs::AckermannDrive &command)
	Velocity command callback.
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.
void	handleSteeringSaturation (double &front_left_steering, double &front_right_steering)
	Update the steering command with steering joint limitation to handle saturation $tan(\delta_{FR})=\frac{wheel_base}{\frac{wheel\_base}{tan(\delta_{FL})}+track)}$ $tan(\delta_{FL})=\frac{wheel_base} {\frac{wheel\_base} {tan(\delta_{FR})} -track)}$ .
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_
realtime_tools::RealtimeBuffer < Commands >	command_ackermann_
	Ackermann command related:
Commands	command_struct_
Commands	command_struct_ackermann_
bool	enable_odom_tf_
	Whether to publish odometry to tf or not:
bool	enable_twist_cmd_
	Whether the control is make with ackermann msg or twist msg:
std::vector < hardware_interface::JointHandle >	front_steering_joints_
std::vector < hardware_interface::JointHandle >	front_wheel_joints_
	Hardware handles:
double	front_wheel_radius_
	Wheel radius (assuming it's the same for the left and right wheels):
Commands	last0_cmd_
Commands	last1_cmd_
	Speed limiters:
ros::Time	last_state_publish_time_
SpeedLimiter	limiter_ang_
SpeedLimiter	limiter_lin_
std::string	name_
boost::shared_ptr < realtime_tools::RealtimePublisher < nav_msgs::Odometry > >	odom_pub_
	Odometry related:
Odometry	odometry_
bool	open_loop_
ros::Duration	publish_period_
	Odometry related:
std::vector < hardware_interface::JointHandle >	rear_wheel_joints_
double	rear_wheel_radius_
double	steering_limit_
	Joint steering limits (assuming the limit is the same for the left and right joint)
ros::Subscriber	sub_command_
ros::Subscriber	sub_command_ackermann_
boost::shared_ptr < realtime_tools::RealtimePublisher < tf::tfMessage > >	tf_odom_pub_
double	track_
	Wheel separation (or track), distance between left and right wheels (from the midpoint of the wheel width):
double	wheel_base_
	Wheel base (distance between front and rear wheel):

Detailed Description

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

the rotation axes of wheels are collinear
the front wheels are identical in radius
the rear 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 28 of file ackermann_controller.h.

Constructor & Destructor Documentation

ackermann_controller::AckermannController::AckermannController ( )

Definition at line 15 of file ackermann_controller.cpp.

Member Function Documentation

void ackermann_controller::AckermannController::brake ( ) [private]

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

Definition at line 440 of file ackermann_controller.cpp.

void ackermann_controller::AckermannController::cmdAckermannCallback ( const ackermann_msgs::AckermannDrive & command ) [private]

Velocity command callback.

Parameters:

command Velocity command message (twist)

Definition at line 476 of file ackermann_controller.cpp.

void ackermann_controller::AckermannController::cmdVelCallback ( const geometry_msgs::Twist & command ) [private]

Velocity command callback.

Parameters:

command Velocity command message (twist)

Definition at line 456 of file ackermann_controller.cpp.

std::string ackermann_controller::AckermannController::getHardwareInterfaceType ( ) const [inline, virtual]

Get the name of this controller's hardware interface type.

Implements controller_interface::ControllerBase.

Definition at line 46 of file ackermann_controller.h.

bool ackermann_controller::AckermannController::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 496 of file ackermann_controller.cpp.

void ackermann_controller::AckermannController::handleSteeringSaturation	(	double &	front_left_steering,
		double &	front_right_steering
	)		`[private]`

Update the steering command with steering joint limitation to handle saturation

$tan(\delta_{FR})=\frac{wheel_base}{\frac{wheel\_base}{tan(\delta_{FL})}+track)}$

$tan(\delta_{FL})=\frac{wheel_base} {\frac{wheel\_base} {tan(\delta_{FR})} -track)}$

.

Parameters:

front_left_steering	$\delta_{FL}$
front_right_steering	$\delta_{FR}$

Definition at line 596 of file ackermann_controller.cpp.

bool ackermann_controller::AckermannController::init	(	hardware_interface::PositionJointInterface *	hw_pos,
		hardware_interface::VelocityJointInterface *	hw_vel,
		ros::NodeHandle &	root_nh,
		ros::NodeHandle &	controller_nh
	)

Definition at line 81 of file ackermann_controller.cpp.

bool ackermann_controller::AckermannController::initRequest	(	hardware_interface::RobotHW *const	robot_hw,
		ros::NodeHandle &	root_nh,
		ros::NodeHandle &	controller_nh,
		std::set< std::string > &	claimed_resources
	)		`[virtual]`

Initialize controller.

Parameters:

robot_hw	Velocity joint interface for the wheels
root_nh	Node handle at root namespace
controller_nh	Node handle inside the controller namespace
claimed_resources	Vector of JointInterfaces claimed during init

Implements controller_interface::ControllerBase.

Definition at line 31 of file ackermann_controller.cpp.