Drake
Drake C++ Documentation
PointToLineDistanceConstraint Class Reference

Detailed Description

Constrain that the distance between a point P on frame B1 and another line L on frame B2 is within a range [distance_lower, distance_upper].

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

Public Member Functions

PointToLineDistanceConstraint (const MultibodyPlant< double > *plant, const Frame< double > &frame_point, const Eigen::Ref< const Eigen::Vector3d > &p_B1P, const Frame< double > &frame_line, const Eigen::Ref< const Eigen::Vector3d > &p_B2Q, const Eigen::Ref< const Eigen::Vector3d > &n_B2, double distance_lower, double distance_upper, systems::Context< double > *plant_context)
Constrain the distance between a point P attached to frame_point (denoted as B1) and the line L attached to frame_line (denoted as B2) is within the range [distance_lower, distance_upper]. More...

PointToLineDistanceConstraint (const MultibodyPlant< AutoDiffXd > *plant, const Frame< AutoDiffXd > &frame_point, const Eigen::Ref< const Eigen::Vector3d > &p_B1P, const Frame< AutoDiffXd > &frame_line, const Eigen::Ref< const Eigen::Vector3d > &p_B2Q, const Eigen::Ref< const Eigen::Vector3d > &n_B2, double distance_lower, double distance_upper, systems::Context< AutoDiffXd > *plant_context)

~PointToLineDistanceConstraint () override

Does not allow copy, move, or assignment
PointToLineDistanceConstraint (const PointToLineDistanceConstraint &)=delete

PointToLineDistanceConstraintoperator= (const PointToLineDistanceConstraint &)=delete

PointToLineDistanceConstraint (PointToLineDistanceConstraint &&)=delete

PointToLineDistanceConstraintoperator= (PointToLineDistanceConstraint &&)=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. More...

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. More...

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. More...

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. More...

Constraint (const Constraint &)=delete

Constraintoperator= (const Constraint &)=delete

Constraint (Constraint &&)=delete

Constraintoperator= (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. More...

void Eval (const Eigen::Ref< const AutoDiffVecXd > &x, AutoDiffVecXd *y) const
Evaluates the expression. More...

void Eval (const Eigen::Ref< const VectorX< symbolic::Variable >> &x, VectorX< symbolic::Expression > *y) const
Evaluates the expression. More...

void set_description (const std::string &description)
Set a human-friendly description for the evaluator. More...

const std::string & get_description () const
Getter for a human-friendly description for the evaluator. More...

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. More...

std::ostream & Display (std::ostream &os) const
Formats this evaluator into the given stream, without displaying the decision variables it is bound to. More...

std::string ToLatex (const VectorX< symbolic::Variable > &vars, int precision=3) const
Returns a LaTeX string describing this evaluator. More...

int num_vars () const
Getter for the number of variables, namely the number of rows in x, as used in Eval(x, y). More...

int num_outputs () const
Getter for the number of outputs, namely the number of rows in y, as used in Eval(x, y). More...

Set the sparsity pattern of the gradient matrix ∂y/∂x (the gradient of y value in Eval, w.r.t x in Eval) . More...

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. More...

EvaluatorBase (const EvaluatorBase &)=delete

EvaluatorBaseoperator= (const EvaluatorBase &)=delete

EvaluatorBase (EvaluatorBase &&)=delete

EvaluatorBaseoperator= (EvaluatorBase &&)=delete

Protected Member Functions inherited from Constraint
void UpdateLowerBound (const Eigen::Ref< const Eigen::VectorXd > &new_lb)

void UpdateUpperBound (const Eigen::Ref< const Eigen::VectorXd > &new_ub)

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. More...

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. More...

virtual std::ostream & DoDisplay (std::ostream &os, const VectorX< symbolic::Variable > &vars) const
NVI implementation of Display. More...

virtual std::string DoToLatex (const VectorX< symbolic::Variable > &vars, int precision) const

void set_num_outputs (int num_outputs)

◆ PointToLineDistanceConstraint() [1/4]

 PointToLineDistanceConstraint ( const PointToLineDistanceConstraint & )
delete

◆ PointToLineDistanceConstraint() [2/4]

 PointToLineDistanceConstraint ( PointToLineDistanceConstraint && )
delete

◆ PointToLineDistanceConstraint() [3/4]

 PointToLineDistanceConstraint ( const MultibodyPlant< double > * plant, const Frame< double > & frame_point, const Eigen::Ref< const Eigen::Vector3d > & p_B1P, const Frame< double > & frame_line, const Eigen::Ref< const Eigen::Vector3d > & p_B2Q, const Eigen::Ref< const Eigen::Vector3d > & n_B2, double distance_lower, double distance_upper, systems::Context< double > * plant_context )

Constrain the distance between a point P attached to frame_point (denoted as B1) and the line L attached to frame_line (denoted as B2) is within the range [distance_lower, distance_upper].

Mathematically, we impose the constraint distance_lower² <= distance(P, L)² <= distance_upper². We impose the constraint on the distance square instead of distance directly, because the gradient of distance is not well defined at distance=0; on the other hand, the gradient of the distance square is well defined everywhere.

We parameterize the line using a point Q on the line, and a directional vector n along the line.

Parameters
 plant The MultibodyPlant on which the constraint is imposed. plant must be alive during the lifetime of this constraint. frame_point The frame B1 to which the point P is attached. p_B1P The position of point P measured and expressed in B1. frame_line The frame B2 to which the line is attached. p_B2Q Q is a point on the line, p_B2Q is the position of this point Q measured and expressed in B2. n_B2 n is the directional vector of the line, n_B2 is this vector measured and expressed in B2. distance_lower The lower bound on the distance, must be non-negative. distance_upper The upper bound on the distance, must be non-negative. plant_context The Context that has been allocated for this plant. We will update the context when evaluating the constraint. plant_context must be alive during the lifetime of this constraint.

◆ PointToLineDistanceConstraint() [4/4]

 PointToLineDistanceConstraint ( const MultibodyPlant< AutoDiffXd > * plant, const Frame< AutoDiffXd > & frame_point, const Eigen::Ref< const Eigen::Vector3d > & p_B1P, const Frame< AutoDiffXd > & frame_line, const Eigen::Ref< const Eigen::Vector3d > & p_B2Q, const Eigen::Ref< const Eigen::Vector3d > & n_B2, double distance_lower, double distance_upper, systems::Context< AutoDiffXd > * plant_context )

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

◆ ~PointToLineDistanceConstraint()

 ~PointToLineDistanceConstraint ( )
override

◆ operator=() [1/2]

 PointToLineDistanceConstraint& operator= ( const PointToLineDistanceConstraint & )
delete

◆ operator=() [2/2]

 PointToLineDistanceConstraint& operator= ( PointToLineDistanceConstraint && )
delete

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