AngleBetweenVectorsConstraint Class Reference

Detailed Description

Constrains that the angle between a vector a and another vector b is between [θ_lower, θ_upper].

a is fixed to a frame A, while b is fixed to a frame B. Mathematically, if we denote a_unit_A as a expressed in frame A after normalization (a_unit_A has unit length), and b_unit_B as b expressed in frame B after normalization, the constraint is cos(θ_upper) ≤ a_unit_Aᵀ * R_AB * b_unit_B ≤ cos(θ_lower)

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

Public Member Functions
	AngleBetweenVectorsConstraint (const MultibodyPlant< double > *plant, const Frame< double > &frameA, const Eigen::Ref< const Eigen::Vector3d > &a_A, const Frame< double > &frameB, const Eigen::Ref< const Eigen::Vector3d > &b_B, double angle_lower, double angle_upper, systems::Context< double > *plant_context)
	Constructs an AngleBetweenVectorsConstraint.
	AngleBetweenVectorsConstraint (const MultibodyPlant< AutoDiffXd > *plant, const Frame< AutoDiffXd > &frameA, const Eigen::Ref< const Eigen::Vector3d > &a_A, const Frame< AutoDiffXd > &frameB, const Eigen::Ref< const Eigen::Vector3d > &b_B, double angle_lower, double angle_upper, systems::Context< AutoDiffXd > *plant_context)
	Overloaded constructor.
	~AngleBetweenVectorsConstraint () override
Does not allow copy, move, or assignment
	AngleBetweenVectorsConstraint (const AngleBetweenVectorsConstraint &)=delete
AngleBetweenVectorsConstraint &	operator= (const AngleBetweenVectorsConstraint &)=delete
	AngleBetweenVectorsConstraint (AngleBetweenVectorsConstraint &&)=delete
AngleBetweenVectorsConstraint &	operator= (AngleBetweenVectorsConstraint &&)=delete
Public Member Functions inherited from Constraint
template<typename DerivedLB, typename DerivedUB>
	Constraint (int num_constraints, int num_vars, const Eigen::MatrixBase< DerivedLB > &lb, const Eigen::MatrixBase< DerivedUB > &ub, const std::string &description="")
	Constructs a constraint which has num_constraints rows, with an input num_vars x 1 vector.
	Constraint (int num_constraints, int num_vars)
	Constructs a constraint which has num_constraints rows, with an input num_vars x 1 vector, with no bounds.
bool	CheckSatisfied (const Eigen::Ref< const Eigen::VectorXd > &x, double tol=1E-6) const
	Return whether this constraint is satisfied by the given value, x.
bool	CheckSatisfied (const Eigen::Ref< const AutoDiffVecXd > &x, double tol=1E-6) const
symbolic::Formula	CheckSatisfied (const Eigen::Ref< const VectorX< symbolic::Variable > > &x) const
const Eigen::VectorXd &	lower_bound () const
const Eigen::VectorXd &	upper_bound () const
int	num_constraints () const
	Number of rows in the output constraint.
	Constraint (const Constraint &)=delete
Constraint &	operator= (const Constraint &)=delete
	Constraint (Constraint &&)=delete
Constraint &	operator= (Constraint &&)=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 Constraint
void	UpdateLowerBound (const Eigen::Ref< const Eigen::VectorXd > &new_lb)
	Updates the lower bound.
void	UpdateUpperBound (const Eigen::Ref< const Eigen::VectorXd > &new_ub)
	Updates the upper bound.
void	set_bounds (const Eigen::Ref< const Eigen::VectorXd > &new_lb, const Eigen::Ref< const Eigen::VectorXd > &new_ub)
	Set the upper and lower bounds of the constraint.
virtual bool	DoCheckSatisfied (const Eigen::Ref< const Eigen::VectorXd > &x, const double tol) const
virtual bool	DoCheckSatisfied (const Eigen::Ref< const AutoDiffVecXd > &x, const double tol) const
virtual symbolic::Formula	DoCheckSatisfied (const Eigen::Ref< const VectorX< symbolic::Variable > > &x) const
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

AngleBetweenVectorsConstraint() [1/4]

AngleBetweenVectorsConstraint ( const AngleBetweenVectorsConstraint & )

delete

AngleBetweenVectorsConstraint() [2/4]

AngleBetweenVectorsConstraint ( AngleBetweenVectorsConstraint && )

delete

AngleBetweenVectorsConstraint() [3/4]

AngleBetweenVectorsConstraint	(	const MultibodyPlant< double > *	plant,
		const Frame< double > &	frameA,
		const Eigen::Ref< const Eigen::Vector3d > &	a_A,
		const Frame< double > &	frameB,
		const Eigen::Ref< const Eigen::Vector3d > &	b_B,
		double	angle_lower,
		double	angle_upper,
		systems::Context< double > *	plant_context )

Constructs an AngleBetweenVectorsConstraint.

Parameters

plant	The MultibodyPlant on which the constraint is imposed. plant should be alive during the lifetime of this constraint.
frameA	The Frame object for frame A.
a_A	The vector a fixed to frame A, expressed in frame A.
frameB	The Frame object for frame B.
b_B	The vector b fixed to frame B, expressed in frameB.
angle_lower	The lower bound on the angle between a and b. It is denoted as θ_lower in the class documentation.
angle_upper	The upper bound on the angle between a and b. it is denoted as θ_upper in the class documentation.
plant_context	The Context that has been allocated for this plant. We will update the context when evaluating the constraint. plant_context should be alive during the lifetime of this constraint.

Precondition

frameA and frameB must belong to plant.

Exceptions

std::exception	if plant is nullptr.
std::exception	if a_A is close to zero.
std::exception	if b_B is close to zero.
std::exception	if angle_lower is negative.
std::exception	if angle_upper ∉ [angle_lower, π].
std::exception	if plant_context is nullptr.

AngleBetweenVectorsConstraint() [4/4]

AngleBetweenVectorsConstraint	(	const MultibodyPlant< AutoDiffXd > *	plant,
		const Frame< AutoDiffXd > &	frameA,
		const Eigen::Ref< const Eigen::Vector3d > &	a_A,
		const Frame< AutoDiffXd > &	frameB,
		const Eigen::Ref< const Eigen::Vector3d > &	b_B,
		double	angle_lower,
		double	angle_upper,
		systems::Context< AutoDiffXd > *	plant_context )

Overloaded constructor.

Use MultibodyPlant<AutoDiffXd> instead of MultibodyPlant<double>.

~AngleBetweenVectorsConstraint()

~AngleBetweenVectorsConstraint ( )

override

Member Function Documentation

operator=() [1/2]

AngleBetweenVectorsConstraint & operator= ( AngleBetweenVectorsConstraint && )

delete

operator=() [2/2]

AngleBetweenVectorsConstraint & operator= ( const AngleBetweenVectorsConstraint & )

delete

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

• drake/multibody/inverse_kinematics/angle_between_vectors_constraint.h