Drake
GazeTargetConstraint Class Reference

Detailed Description

Constrains a target point T to be within a cone K.

The point T ("T" stands for "target") is fixed in a frame B, with position p_BT. The cone originates from a point S ("S" stands for "source"), fixed in frame A with position p_AS, with the axis of the cone being n, also fixed in frame A. The half angle of the cone is θ. A common usage of this constraint is that a camera should gaze at some target; namely the target falls within a gaze cone, originating from the camera eye.

Mathematically the constraint is p_ST_Aᵀ * n_unit_A ≥ 0 (p_ST_Aᵀ * n_unit_A)² ≥ (cosθ)²p_ST_Aᵀ * p_ST_A where p_ST_A is the vector from S to T, expressed in frame A. n_unit_A is the unit length directional vector representing the center ray of the cone.

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

Public Member Functions

 GazeTargetConstraint (const MultibodyPlant< double > *plant, const Frame< double > &frameA, const Eigen::Ref< const Eigen::Vector3d > &p_AS, const Eigen::Ref< const Eigen::Vector3d > &n_A, const Frame< double > &frameB, const Eigen::Ref< const Eigen::Vector3d > &p_BT, double cone_half_angle, systems::Context< double > *plant_context)
 
 GazeTargetConstraint (const MultibodyPlant< AutoDiffXd > *plant, const Frame< AutoDiffXd > &frameA, const Eigen::Ref< const Eigen::Vector3d > &p_AS, const Eigen::Ref< const Eigen::Vector3d > &n_A, const Frame< AutoDiffXd > &frameB, const Eigen::Ref< const Eigen::Vector3d > &p_BT, double cone_half_angle, systems::Context< AutoDiffXd > *plant_context)
 Overloaded constructor. More...
 
 ~GazeTargetConstraint () override
 
Does not allow copy, move, or assignment
 GazeTargetConstraint (const GazeTargetConstraint &)=delete
 
GazeTargetConstraintoperator= (const GazeTargetConstraint &)=delete
 
 GazeTargetConstraint (GazeTargetConstraint &&)=delete
 
GazeTargetConstraintoperator= (GazeTargetConstraint &&)=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...
 
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...
 
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) . More...
 
const 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
 

Additional Inherited Members

- Protected Member Functions inherited from Constraint
void UpdateLowerBound (const Eigen::Ref< const Eigen::VectorXd > &new_lb)
 Updates the lower bound. More...
 
void UpdateUpperBound (const Eigen::Ref< const Eigen::VectorXd > &new_ub)
 Updates the upper bound. More...
 
void set_bounds (const Eigen::Ref< const Eigen::VectorXd > &lower_bound, const Eigen::Ref< const Eigen::VectorXd > &upper_bound)
 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...
 
void set_num_outputs (int num_outputs)
 

Constructor & Destructor Documentation

◆ GazeTargetConstraint() [1/4]

◆ GazeTargetConstraint() [2/4]

◆ GazeTargetConstraint() [3/4]

GazeTargetConstraint ( const MultibodyPlant< double > *  plant,
const Frame< double > &  frameA,
const Eigen::Ref< const Eigen::Vector3d > &  p_AS,
const Eigen::Ref< const Eigen::Vector3d > &  n_A,
const Frame< double > &  frameB,
const Eigen::Ref< const Eigen::Vector3d > &  p_BT,
double  cone_half_angle,
systems::Context< double > *  plant_context 
)
Parameters
plantThe MultibodyPlant on which the constraint is imposed. plant should be alive during the lifetime of this constraint.
frameAThe frame to which the gaze cone is fixed.
p_ASThe position of the cone source point S, measured and expressed in frame A.
n_AThe directional vector representing the center ray of the cone, expressed in frame A.
frameBThe frame to which the target point T is fixed.
p_BTThe position of the target point T, measured and expressed in frame B.
cone_half_angleThe half angle of the cone. We denote it as θ in the class documentation. cone_half_angle is in radians.
plant_contextThe 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::invalid_argumentif plant is nullptr.
std::invalid_argumentif n_A is close to zero.
std::invalid_argumentif cone_half_angle ∉ [0, π/2].
std::invalid_argumentif plant_context is nullptr.

◆ GazeTargetConstraint() [4/4]

GazeTargetConstraint ( const MultibodyPlant< AutoDiffXd > *  plant,
const Frame< AutoDiffXd > &  frameA,
const Eigen::Ref< const Eigen::Vector3d > &  p_AS,
const Eigen::Ref< const Eigen::Vector3d > &  n_A,
const Frame< AutoDiffXd > &  frameB,
const Eigen::Ref< const Eigen::Vector3d > &  p_BT,
double  cone_half_angle,
systems::Context< AutoDiffXd > *  plant_context 
)

Overloaded constructor.

Construct from MultibodyPlant<AutoDiffXd> instead of MultibodyPlant<double>.

◆ ~GazeTargetConstraint()

~GazeTargetConstraint ( )
override

Member Function Documentation

◆ operator=() [1/2]

GazeTargetConstraint& operator= ( const GazeTargetConstraint )
delete

◆ operator=() [2/2]

GazeTargetConstraint& operator= ( GazeTargetConstraint &&  )
delete

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