StaticEquilibriumConstraint Class Reference

Detailed Description

Impose the static equilibrium constraint 0 = τ_g + Bu + ∑J_WBᵀ(q) * Fapp_B_W.

#include <drake/multibody/optimization/static_equilibrium_constraint.h>

Public Member Functions
	~StaticEquilibriumConstraint () override
const std::map< SortedPair< geometry::GeometryId >, GeometryPairContactWrenchEvaluatorBinding > &	contact_pair_to_wrench_evaluator () const
	Getter for contact_pair_to_wrench_evaluator, passed in the constructor.
Does not allow copy, move, or assignment
	StaticEquilibriumConstraint (const StaticEquilibriumConstraint &)=delete
StaticEquilibriumConstraint &	operator= (const StaticEquilibriumConstraint &)=delete
	StaticEquilibriumConstraint (StaticEquilibriumConstraint &&)=delete
StaticEquilibriumConstraint &	operator= (StaticEquilibriumConstraint &&)=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

Static Public Member Functions
static solvers::Binding< StaticEquilibriumConstraint >	MakeBinding (const MultibodyPlant< AutoDiffXd > *plant, systems::Context< AutoDiffXd > *context, const std::vector< std::pair< std::shared_ptr< ContactWrenchEvaluator >, VectorX< symbolic::Variable > > > &contact_wrench_evaluators_and_lambda, const Eigen::Ref< const VectorX< symbolic::Variable > > &q_vars, const Eigen::Ref< const VectorX< symbolic::Variable > > &u_vars)
	Create a static equilibrium constraint 0 = g(q) + Bu + ∑ᵢ JᵢᵀFᵢ_AB_W(λᵢ) This constraint depends on the variables q, u and λ.

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

StaticEquilibriumConstraint() [1/2]

StaticEquilibriumConstraint ( const StaticEquilibriumConstraint & )

delete

StaticEquilibriumConstraint() [2/2]

StaticEquilibriumConstraint ( StaticEquilibriumConstraint && )

delete

~StaticEquilibriumConstraint()

~StaticEquilibriumConstraint ( )

override

Member Function Documentation

contact_pair_to_wrench_evaluator()

const std::map< SortedPair< geometry::GeometryId >, GeometryPairContactWrenchEvaluatorBinding > & contact_pair_to_wrench_evaluator

(

)

const

Getter for contact_pair_to_wrench_evaluator, passed in the constructor.

MakeBinding()

solvers::Binding< StaticEquilibriumConstraint > MakeBinding ( const MultibodyPlant< AutoDiffXd > * plant, systems::Context< AutoDiffXd > * context, const std::vector< std::pair< std::shared_ptr< ContactWrenchEvaluator >, VectorX< symbolic::Variable > > > & contact_wrench_evaluators_and_lambda, const Eigen::Ref< const VectorX< symbolic::Variable > > & q_vars, const Eigen::Ref< const VectorX< symbolic::Variable > > & u_vars )

static

Create a static equilibrium constraint 0 = g(q) + Bu + ∑ᵢ JᵢᵀFᵢ_AB_W(λᵢ) This constraint depends on the variables q, u and λ.

Parameters

plant	The plant on which the constraint is imposed.
context	The context for the subsystem plant.
contact_wrench_evaluators_and_lambda	For each contact pair, we need to compute the contact wrench applied at the point of contact, expressed in the world frame, namely Fᵢ_AB_W(λᵢ). contact_wrench_evaluators_and_lambda.first is the evaluator for computing this contact wrench from the variables λᵢ. contact_wrench_evaluators_and_lambda.second are the decision variable λᵢ used in computing the contact wrench. Notice the generalized position q is not included in variables contact_wrench_evaluators_and_lambda.second.
q_vars	The decision variables for q (the generalized position).
u_vars	The decision variables for u (the input).

Returns

binding The binding between the static equilibrium constraint and the variables q, u and λ.

Precondition

plant must have been connected to a SceneGraph properly. You could refer to AddMultibodyPlantSceneGraph on how to connect a MultibodyPlant to a SceneGraph.

operator=() [1/2]

StaticEquilibriumConstraint & operator= ( const StaticEquilibriumConstraint & )

delete

operator=() [2/2]

StaticEquilibriumConstraint & operator= ( StaticEquilibriumConstraint && )

delete

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

• drake/multibody/optimization/static_equilibrium_constraint.h