PositionCost Class Reference

Detailed Description

Implements a cost of the form (p_AP - p_AQ)ᵀ C (p_AP - p_AQ), where point P is specified relative to frame A and point Q is specified relative to frame B, and the cost is evaluated in frame A.

#include <drake/multibody/inverse_kinematics/position_cost.h>

Public Member Functions
	PositionCost (const MultibodyPlant< double > *plant, const Frame< double > &frameA, const Eigen::Ref< const Eigen::Vector3d > &p_AP, const Frame< double > &frameB, const Eigen::Ref< const Eigen::Vector3d > &p_BQ, const Eigen::Ref< const Eigen::Matrix3d > &C, systems::Context< double > *plant_context)
	Constructs PositionCost object.
	PositionCost (const MultibodyPlant< AutoDiffXd > *plant, const Frame< AutoDiffXd > &frameA, const Eigen::Ref< const Eigen::Vector3d > &p_AP, const Frame< AutoDiffXd > &frameB, const Eigen::Ref< const Eigen::Vector3d > &p_BQ, const Eigen::Ref< const Eigen::Matrix3d > &C, systems::Context< AutoDiffXd > *plant_context)
	Overloaded constructor.
	~PositionCost () override
Does not allow copy, move, or assignment
	PositionCost (const PositionCost &)=delete
PositionCost &	operator= (const PositionCost &)=delete
	PositionCost (PositionCost &&)=delete
PositionCost &	operator= (PositionCost &&)=delete
Public Member Functions inherited from Cost
	Cost (const Cost &)=delete
Cost &	operator= (const Cost &)=delete
	Cost (Cost &&)=delete
Cost &	operator= (Cost &&)=delete
Public Member Functions inherited from EvaluatorBase
virtual	~EvaluatorBase ()
void	Eval (const Eigen::Ref< const Eigen::VectorXd > &x, Eigen::VectorXd *y) const
	Evaluates the expression.
void	Eval (const Eigen::Ref< const AutoDiffVecXd > &x, AutoDiffVecXd *y) const
	Evaluates the expression.
void	Eval (const Eigen::Ref< const VectorX< symbolic::Variable > > &x, VectorX< symbolic::Expression > *y) const
	Evaluates the expression.
void	set_description (const std::string &description)
	Set a human-friendly description for the evaluator.
const std::string &	get_description () const
	Getter for a human-friendly description for the evaluator.
std::ostream &	Display (std::ostream &os, const VectorX< symbolic::Variable > &vars) const
	Formats this evaluator into the given stream using vars for the bound decision variable names.
std::ostream &	Display (std::ostream &os) const
	Formats this evaluator into the given stream, without displaying the decision variables it is bound to.
std::string	ToLatex (const VectorX< symbolic::Variable > &vars, int precision=3) const
	Returns a LaTeX string describing this evaluator.
int	num_vars () const
	Getter for the number of variables, namely the number of rows in x, as used in Eval(x, y).
int	num_outputs () const
	Getter for the number of outputs, namely the number of rows in y, as used in Eval(x, y).
void	SetGradientSparsityPattern (const std::vector< std::pair< int, int > > &gradient_sparsity_pattern)
	Set the sparsity pattern of the gradient matrix ∂y/∂x (the gradient of y value in Eval, w.r.t x in Eval) .
const std::optional< std::vector< std::pair< int, int > > > &	gradient_sparsity_pattern () const
	Returns the vector of (row_index, col_index) that contains all the entries in the gradient of Eval function (∂y/∂x) whose value could be non-zero, namely if ∂yᵢ/∂xⱼ could be non-zero, then the pair (i, j) is in gradient_sparsity_pattern.
bool	is_thread_safe () const
	Returns whether it is safe to call Eval in parallel.
	EvaluatorBase (const EvaluatorBase &)=delete
EvaluatorBase &	operator= (const EvaluatorBase &)=delete
	EvaluatorBase (EvaluatorBase &&)=delete
EvaluatorBase &	operator= (EvaluatorBase &&)=delete

Additional Inherited Members
Protected Member Functions inherited from Cost
	Cost (int num_vars, const std::string &description="")
	Constructs a cost evaluator.
Protected Member Functions inherited from EvaluatorBase
	EvaluatorBase (int num_outputs, int num_vars, const std::string &description="")
	Constructs a evaluator.
virtual std::ostream &	DoDisplay (std::ostream &os, const VectorX< symbolic::Variable > &vars) const
	NVI implementation of Display.
virtual std::string	DoToLatex (const VectorX< symbolic::Variable > &vars, int precision) const
void	set_num_outputs (int num_outputs)
void	set_is_thread_safe (bool is_thread_safe)

Constructor & Destructor Documentation

PositionCost() [1/4]

PositionCost ( const PositionCost & )

delete

PositionCost() [2/4]

PositionCost ( PositionCost && )

delete

PositionCost() [3/4]

PositionCost	(	const MultibodyPlant< double > *	plant,
		const Frame< double > &	frameA,
		const Eigen::Ref< const Eigen::Vector3d > &	p_AP,
		const Frame< double > &	frameB,
		const Eigen::Ref< const Eigen::Vector3d > &	p_BQ,
		const Eigen::Ref< const Eigen::Matrix3d > &	C,
		systems::Context< double > *	plant_context )

Constructs PositionCost object.

Parameters

plant	The MultibodyPlant on which the cost is implemented. plant should be alive during the lifetime of this cost.
frameA	The frame in which point P's position is measured.
p_AP	The point P.
frameB	The frame in which point Q's position is measured.
p_BQ	The point Q.
C	A 3x3 matrix representing the cost in quadratic form.
plant_context	A context for the plant.

Exceptions

std::exception	if plant is nullptr.
std::exception	if plant_context is nullptr.

PositionCost() [4/4]

PositionCost	(	const MultibodyPlant< AutoDiffXd > *	plant,
		const Frame< AutoDiffXd > &	frameA,
		const Eigen::Ref< const Eigen::Vector3d > &	p_AP,
		const Frame< AutoDiffXd > &	frameB,
		const Eigen::Ref< const Eigen::Vector3d > &	p_BQ,
		const Eigen::Ref< const Eigen::Matrix3d > &	C,
		systems::Context< AutoDiffXd > *	plant_context )

Overloaded constructor.

Same as the constructor with the double version (using MultibodyPlant<double> and Context<double>). Except the gradient of the cost is computed from autodiff.

~PositionCost()

~PositionCost ( )

override

Member Function Documentation

operator=() [1/2]

PositionCost & operator= ( const PositionCost & )

delete

operator=() [2/2]

PositionCost & operator= ( PositionCost && )

delete

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

• drake/multibody/inverse_kinematics/position_cost.h