sr_friction_compensation::SrFrictionCompensator Class Reference

#include <sr_friction_compensation.hpp>

Public Member Functions
double	friction_compensation (double position, double velocity, int force_demand, int deadband)
	SrFrictionCompensator (const std::string &joint_name)
	~SrFrictionCompensator ()

Private Member Functions
std::vector< joint_calibration::Point >	generate_flat_map ()
std::pair< std::vector< joint_calibration::Point >, std::vector< joint_calibration::Point > >	read_friction_map ()
std::vector< joint_calibration::Point >	read_one_way_map (XmlRpc::XmlRpcValue &raw_map)

Private Attributes
boost::scoped_ptr< shadow_robot::JointCalibration >	friction_interpoler_backward
	An interpolator for the backward friction map: used to compute the offset from the map, given the current pos. More...
boost::scoped_ptr< shadow_robot::JointCalibration >	friction_interpoler_forward
	An interpolator for the forward friction map: used to compute the offset from the map, given the current pos. More...
std::string	joint_name_
ros::NodeHandle	node_
	node handle for reading the map from the parameters server. More...

Static Private Attributes
static const double	velocity_for_static_friction = 0.01

Detailed Description

Definition at line 49 of file sr_friction_compensation.hpp.

Constructor & Destructor Documentation

sr_friction_compensation::SrFrictionCompensator::SrFrictionCompensator ( const std::string &  joint_name )

explicit

Definition at line 44 of file sr_friction_compensation.cpp.

sr_friction_compensation::SrFrictionCompensator::~SrFrictionCompensator

(

)

Definition at line 52 of file sr_friction_compensation.cpp.

Member Function Documentation

double sr_friction_compensation::SrFrictionCompensator::friction_compensation	(	double	position,
		double	velocity,
		int	force_demand,
		int	deadband
	)

Computes the value of the offset to add to the force demand to compensate for the friction. This offset is computed based on the current joint position and on the force demand sign as well, using a friction map.

The friction map is generated by moving the joint very slowly, from one end to the other, while recording the force necessary to move it. Two different map position->force are then created by interpolating those values, one for each direction.

Parameters

position	the current joint position.
velocity	the current joint velocity.
force_demand	the force demand is used to know in which direction we want to move: if > 0 -> forward if < 0 -> backward
deadband	the deadband on the force_demand (in the deadband region, we're returning an offset of 0.0 for stability reasons).

Returns

the force necessary to have the joint ready to move.

Definition at line 56 of file sr_friction_compensation.cpp.

vector< joint_calibration::Point > sr_friction_compensation::SrFrictionCompensator::generate_flat_map ( )

private

Generates a flat map for the joints missing one of their friction map.

Returns

A flat map (always 0.0)

Definition at line 206 of file sr_friction_compensation.cpp.

pair< vector< joint_calibration::Point >, vector< joint_calibration::Point > > sr_friction_compensation::SrFrictionCompensator::read_friction_map ( )

private

Read the 2 friction maps from the parameter servers for each joint. Generate a flat map (no offset) if the map doesn't exist.

Returns

a pair of map: the first is the forward map, the second is the backward map.

Definition at line 103 of file sr_friction_compensation.cpp.

vector< joint_calibration::Point > sr_friction_compensation::SrFrictionCompensator::read_one_way_map ( XmlRpc::XmlRpcValue &  raw_map )

private

Format one map from the given raw map directly taken from the parameter server.

Parameters

raw_map

the raw_map directly read from the parameters.

Returns

The map (either forward or backward)

Definition at line 183 of file sr_friction_compensation.cpp.

Member Data Documentation

boost::scoped_ptr<shadow_robot::JointCalibration> sr_friction_compensation::SrFrictionCompensator::friction_interpoler_backward

private

An interpolator for the backward friction map: used to compute the offset from the map, given the current pos.

Definition at line 115 of file sr_friction_compensation.hpp.

boost::scoped_ptr<shadow_robot::JointCalibration> sr_friction_compensation::SrFrictionCompensator::friction_interpoler_forward

private

An interpolator for the forward friction map: used to compute the offset from the map, given the current pos.

Definition at line 113 of file sr_friction_compensation.hpp.

std::string sr_friction_compensation::SrFrictionCompensator::joint_name_

private

Definition at line 118 of file sr_friction_compensation.hpp.

ros::NodeHandle sr_friction_compensation::SrFrictionCompensator::node_

private

node handle for reading the map from the parameters server.

Definition at line 82 of file sr_friction_compensation.hpp.

const double sr_friction_compensation::SrFrictionCompensator::velocity_for_static_friction = 0.01

staticprivate

Definition at line 121 of file sr_friction_compensation.hpp.

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

• sr_friction_compensation.hpp
• sr_friction_compensation.cpp