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 > *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 > *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 > *  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.
contextThe Context that has been allocated for this plant. We will update the context when evaluating the constraint. 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 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 > *  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: