KDL::Path_Line Class Reference
[Motion]

A path representing a line from A to B. More...

#include <path_line.hpp>

Inheritance diagram for KDL::Path_Line:

Public Member Functions
virtual Twist	Acc (double s, double sd, double sdd) const
	Returns the acceleration twist at path length s and with derivative of s == sd, and 2nd derivative of s == sdd.
virtual Path *	Clone ()
	Virtual constructor, constructing by copying, Returns a deep copy of this Path Object.
double	LengthToS (double length)
	LengthToS() converts a physical length along the trajectory to the parameter s used in Pos, Vel and Acc.
	Path_Line (const Frame &F_base_start, const Twist &twist_in_base, RotationalInterpolation *orient, double eqradius, bool _aggregate=true)
	Path_Line (const Frame &F_base_start, const Frame &F_base_end, RotationalInterpolation *orient, double eqradius, bool _aggregate=true)
	Constructs a Line Path F_base_start and F_base_end give the begin and end frame wrt the base orient gives the method of rotation interpolation eqradius : equivalent radius : serves to compare rotations and translations.
virtual double	PathLength ()
	Returns the total path length of the trajectory (has dimension LENGTH) This is not always a physical length , ie when dealing with rotations that are dominant.
virtual Frame	Pos (double s) const
	Returns the Frame at the current path length s.
virtual Twist	Vel (double s, double sd) const
	Returns the velocity twist at path length s theta and with derivative of s == sd.
virtual void	Write (std::ostream &os)
	Writes one of the derived objects to the stream.
virtual	~Path_Line ()

Detailed Description

A path representing a line from A to B.

Definition at line 59 of file path_line.hpp.

Constructor & Destructor Documentation

KDL::Path_Line::Path_Line	(	const Frame &	F_base_start,
		const Frame &	F_base_end,
		RotationalInterpolation *	orient,
		double	eqradius,
		bool	_aggregate = `true`
	)

Constructs a Line Path F_base_start and F_base_end give the begin and end frame wrt the base orient gives the method of rotation interpolation eqradius : equivalent radius : serves to compare rotations and translations.

the "amount of motion"(pos,vel,acc) of the rotation is taken to be the amount motion of a point at distance eqradius from the rotation axis.

Eqradius is introduced because it is unavoidable that you have to compare rotations and translations : e.g. : You can have motions that only contain rotation, and motions that only contain translations. The motion planning goes as follows :

translation is planned with the given parameters
rotation is planned planned with the parameters calculated with eqradius.
The longest of the previous two remains unchanged, the shortest in duration is scaled to take as long as the longest. This guarantees that the geometric path in 6D space remains independent of the motion profile parameters.

RotationalInterpolation_SingleAxis() has the advantage that it is independent of the frame in which you express your path. Other implementations for RotationalInterpolations COULD be (not implemented) (yet) : 1) quaternion interpolation : but this is more difficult for the human to interprete 2) 3-axis interpolation : express the orientation of the frame in e.g. euler zyx angles alfa,beta, gamma and interpolate these parameters. But this is dependent of the frame you choose as a reference and their can occur representation singularities.

Definition at line 47 of file path_line.cpp.

References KDL::RotationalInterpolation::Angle(), draftlibs::fcvec::dist(), KDL::Frame::M, KDL::Vector::Normalize(), and KDL::RotationalInterpolation::SetStartEnd().

Referenced by Clone().

KDL::Path_Line::Path_Line	(	const Frame &	F_base_start,
		const Twist &	twist_in_base,
		RotationalInterpolation *	orient,
		double	eqradius,
		bool	_aggregate = `true`
	)

Definition at line 86 of file path_line.cpp.

References KDL::RotationalInterpolation::Angle(), draftlibs::fcvec::dist(), KDL::Frame::M, KDL::Vector::Norm(), KDL::Vector::Normalize(), KDL::Twist::rot, KDL::Rotation::Rot(), KDL::RotationalInterpolation::SetStartEnd(), and KDL::Twist::vel.

KDL::Path_Line::~Path_Line ( ) [virtual]

Definition at line 148 of file path_line.cpp.

Member Function Documentation

Twist KDL::Path_Line::Acc	(	double	s,
		double	sd,
		double	sdd
	)			const `[virtual]`

Returns the acceleration twist at path length s and with derivative of s == sd, and 2nd derivative of s == sdd.

Implements KDL::Path.

Definition at line 143 of file path_line.cpp.

References KDL::RotationalInterpolation::Acc().

Path * KDL::Path_Line::Clone ( ) [virtual]

Virtual constructor, constructing by copying, Returns a deep copy of this Path Object.

Implements KDL::Path.

Definition at line 153 of file path_line.cpp.

References KDL::RotationalInterpolation::Clone(), Path_Line(), and KDL::RotationalInterpolation::Pos().

double KDL::Path_Line::LengthToS ( double length ) [virtual]

LengthToS() converts a physical length along the trajectory to the parameter s used in Pos, Vel and Acc.

This is used because in cases with large rotations the parameter s does NOT correspond to the lineair length along the trajectory. User should be sure that the lineair distance travelled by this path object is NOT zero, when using this method ! (e.g. the case of only rotational change) throws Error_MotionPlanning_Not_Applicable if used on composed path objects.

Implements KDL::Path.

Definition at line 129 of file path_line.cpp.

double KDL::Path_Line::PathLength ( ) [virtual]

Returns the total path length of the trajectory (has dimension LENGTH) This is not always a physical length , ie when dealing with rotations that are dominant.

Implements KDL::Path.

Definition at line 132 of file path_line.cpp.

Frame KDL::Path_Line::Pos ( double s ) const [virtual]

Returns the Frame at the current path length s.

Implements KDL::Path.

Definition at line 135 of file path_line.cpp.

References KDL::RotationalInterpolation::Pos().