Drake
RigidBodyPlant< T > Class Template Reference

This class provides a System interface around a multibody dynamics model of the world represented by a RigidBodyTree. More...

#include <drake/multibody/rigid_body_plant/contact_results.h>

Inheritance diagram for RigidBodyPlant< T >:
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Collaboration diagram for RigidBodyPlant< T >:
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## Public Member Functions

RigidBodyPlant (std::unique_ptr< const RigidBodyTree< T >> tree, double timestep=0.0)
Instantiates a RigidBodyPlant from a Multi-Body Dynamics (MBD) model of the world in tree. More...

~RigidBodyPlant () override

void set_normal_contact_parameters (double penetration_stiffness, double dissipation)
Sets only the parameters for normal contact. More...

void set_friction_contact_parameters (double static_friction_coef, double dynamic_friction_coef, double v_stiction_tolerance)
Sets only the parameters for friction contact. More...

const RigidBodyTree< T > & get_rigid_body_tree () const
Returns a constant reference to the multibody dynamics model of the world. More...

int get_num_bodies () const
Returns the number of bodies in the world. More...

int get_num_positions () const
Returns the number of generalized coordinates of the model. More...

int get_num_positions (int model_instance_id) const
Returns the number of generalized coordinates for a specific model instance. More...

int get_num_velocities () const
Returns the number of generalized velocities of the model. More...

int get_num_velocities (int model_instance_id) const
Returns the number of generalized velocities for a specific model instance. More...

int get_num_states () const
Returns the size of the continuous state of the system which equals get_num_positions() plus get_num_velocities(). More...

int get_num_states (int model_instance_id) const
Returns the size of the continuous state of a specific model instance which equals get_num_positions() plus get_num_velocities(). More...

int get_num_actuators () const
Returns the number of actuators. More...

int get_num_actuators (int model_instance_id) const
Returns the number of actuators for a specific model instance. More...

int get_num_model_instances () const
Returns the number of model instances in the world, not including the world. More...

int get_input_size () const
Returns the size of the input vector to the system. More...

int get_output_size () const
Returns the size of the output vector of the system. More...

void set_position (Context< T > *context, int position_index, T position) const
Sets the generalized coordinate position_index to the value position. More...

void set_velocity (Context< T > *context, int velocity_index, T velocity) const
Sets the generalized velocity velocity_index to the value velocity. More...

void set_state_vector (Context< T > *context, const Eigen::Ref< const VectorX< T >> x) const
Sets the continuous state vector of the system to be x. More...

void set_state_vector (State< T > *state, const Eigen::Ref< const VectorX< T >> x) const
Sets the continuous state vector of the system to be x. More...

void SetDefaultState (const Context< T > &, State< T > *state) const override
Sets the state in context so that generalized positions and velocities are zero. More...

int FindInstancePositionIndexFromWorldIndex (int model_instance_id, int world_position_index)
Returns the index into the output port for model_instance_id which corresponds to the world position index of world_position_index, or throws if the position index does not correspond to the model id. More...

Eigen::VectorBlock< const VectorX< T > > GetStateVector (const Context< T > &context) const

bool is_state_discrete () const
Gets whether this system is modeled using discrete state. More...

double get_time_step () const
Get the time step used to construct the plant. More...

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

RigidBodyPlantoperator= (const RigidBodyPlant &)=delete

RigidBodyPlant (RigidBodyPlant &&)=delete

RigidBodyPlantoperator= (RigidBodyPlant &&)=delete

System input port descriptor accessors.

These are accessors for obtaining descriptors of this RigidBodyPlant's input ports.

See this class's description for details about these ports and how these accessors are typically used.

const InputPortDescriptor< T > & actuator_command_input_port () const
Returns a descriptor of the actuator command input port. More...

bool model_instance_has_actuators (int model_instance_id) const
Returns true if and only if the model instance with the provided model_instance_id has actuators. More...

const InputPortDescriptor< T > & model_instance_actuator_command_input_port (int model_instance_id) const
Returns a descriptor of the input port for a specific model instance. More...

System output port accessors.

These are accessors for obtaining this RigidBodyPlant's output ports.

See this class's description for details about these ports and how these accessors are typically used.

const OutputPort< T > & state_output_port () const
Returns the plant-centric state output port. More...

const OutputPort< T > & model_instance_state_output_port (int model_instance_id) const
Returns he output port containing the state of a particular model with instance ID equal to model_instance_id. More...

const OutputPort< T > & kinematics_results_output_port () const
Returns the KinematicsResults output port. More...

const OutputPort< T > & contact_results_output_port () const
Returns the ContactResults output port. More...

Public Member Functions inherited from LeafSystem< T >
~LeafSystem () override

std::unique_ptr< CompositeEventCollection< T > > AllocateCompositeEventCollection () const final
Allocates a CompositeEventCollection object for this system. More...

std::unique_ptr< Context< T > > AllocateContext () const override
Allocates a context, initialized with the correct numbers of concrete input ports and state variables for this System. More...

void SetDefaultState (const Context< T > &context, State< T > *state) const override
Default implementation: sets all continuous state to the model vector given in DeclareContinousState (or zero if no model vector was given) and discrete states to zero. More...

void SetDefaultParameters (const Context< T > &context, Parameters< T > *parameters) const override
Default implementation: sets all numeric parameters to the model vector given to DeclareNumericParameter, or else if no model was provided sets the numeric parameter to one. More...

std::unique_ptr< SystemOutput< T > > AllocateOutput (const Context< T > &context) const final
Returns a container that can hold the values of all of this System's output ports. More...

std::unique_ptr< ContinuousState< T > > AllocateTimeDerivatives () const override
Returns the AllocateContinuousState value, which must not be nullptr. More...

std::unique_ptr< DiscreteValues< T > > AllocateDiscreteVariables () const override
Returns the AllocateDiscreteState value, which must not be nullptr. More...

std::multimap< int, intGetDirectFeedthroughs () const final
Reports all direct feedthroughs from input ports to output ports. More...

LeafSystem (const LeafSystem &)=delete

LeafSystemoperator= (const LeafSystem &)=delete

LeafSystem (LeafSystem &&)=delete

LeafSystemoperator= (LeafSystem &&)=delete

Public Member Functions inherited from System< T >
virtual ~System ()

void GetWitnessFunctions (const Context< T > &context, std::vector< const WitnessFunction< T > * > *w) const
Gets the witness functions active at the beginning of a continuous time interval. More...

EvaluateWitness (const Context< T > &context, const WitnessFunction< T > &witness_func) const
Evaluates a witness function at the given context. More...

std::string GetSystemIdString () const
Returns a string suitable for identifying this particular System in error messages, when it is a subsystem of a larger Diagram. More...

System (const System &)=delete

Systemoperator= (const System &)=delete

System (System &&)=delete

Systemoperator= (System &&)=delete

std::unique_ptr< BasicVector< T > > AllocateInputVector (const InputPortDescriptor< T > &descriptor) const
Given a port descriptor, allocates the vector storage. More...

std::unique_ptr< AbstractValueAllocateInputAbstract (const InputPortDescriptor< T > &descriptor) const
Given a port descriptor, allocates the abstract storage. More...

std::unique_ptr< Context< T > > CreateDefaultContext () const
This convenience method allocates a context using AllocateContext() and sets its default values using SetDefaultContext(). More...

void SetDefaultContext (Context< T > *context) const

virtual void SetRandomState (const Context< T > &context, State< T > *state, RandomGenerator *generator) const
Assigns random values to all elements of the state. More...

virtual void SetRandomParameters (const Context< T > &context, Parameters< T > *parameters, RandomGenerator *generator) const
Assigns random values to all parameters. More...

void SetRandomContext (Context< T > *context, RandomGenerator *generator) const

void AllocateFreestandingInputs (Context< T > *context) const
For each input port, allocates a freestanding input of the concrete type that this System requires, and binds it to the port, disconnecting any prior input. More...

bool HasAnyDirectFeedthrough () const
Returns true if any of the inputs to the system might be directly fed through to any of its outputs and false otherwise. More...

bool HasDirectFeedthrough (int output_port) const
Returns true if there might be direct-feedthrough from any input port to the given output_port, and false otherwise. More...

bool HasDirectFeedthrough (int input_port, int output_port) const
Returns true if there might be direct-feedthrough from the given input_port to the given output_port, and false otherwise. More...

void Publish (const Context< T > &context, const EventCollection< PublishEvent< T >> &events) const
This method is the public entry point for dispatching all publish event handlers. More...

void Publish (const Context< T > &context) const
Forces a publish on the system, given a context. More...

const T & EvalConservativePower (const Context< T > &context) const
Returns a reference to the cached value of the conservative power. More...

const T & EvalNonConservativePower (const Context< T > &context) const
Returns a reference to the cached value of the non-conservative power. More...

template<template< typename > class Vec = BasicVector>
const Vec< T > * EvalVectorInput (const Context< T > &context, int port_index) const
Causes the vector-valued input port with the given port_index to become up-to-date, delegating to our parent Diagram if necessary. More...

Eigen::VectorBlock< const VectorX< T > > EvalEigenVectorInput (const Context< T > &context, int port_index) const
Causes the vector-valued input port with the given port_index to become up-to-date, delegating to our parent Diagram if necessary. More...

const AbstractValueEvalAbstractInput (const Context< T > &context, int port_index) const
Causes the abstract-valued input port with the given port_index to become up-to-date, delegating to our parent Diagram if necessary. More...

template<typename V >
const V * EvalInputValue (const Context< T > &context, int port_index) const
Causes the abstract-valued input port with the given port_index to become up-to-date, delegating to our parent Diagram if necessary. More...

int get_num_constraint_equations (const Context< T > &context) const
Gets the number of constraint equations for this system using the given context (useful in case the number of constraints is dependent upon the current state (as might be the case with a system modeled using piecewise differential algebraic equations). More...

Eigen::VectorXd EvalConstraintEquations (const Context< T > &context) const
Evaluates the constraint equations for the system at the generalized coordinates and generalized velocity specified by the context. More...

Eigen::VectorXd EvalConstraintEquationsDot (const Context< T > &context) const
Computes the time derivative of each constraint equation, evaluated at the generalized coordinates and generalized velocity specified by the context. More...

Eigen::VectorXd CalcVelocityChangeFromConstraintImpulses (const Context< T > &context, const Eigen::MatrixXd &J, const Eigen::VectorXd &lambda) const
Computes the change in velocity from applying the given constraint forces to the system at the given context. More...

double CalcConstraintErrorNorm (const Context< T > &context, const Eigen::VectorXd &error) const
Computes the norm on constraint error (used as a metric for comparing errors between the outputs of algebraic equations applied to two different state variable instances). More...

void CalcTimeDerivatives (const Context< T > &context, ContinuousState< T > *derivatives) const
Calculates the time derivatives xcdot of the continuous state xc. More...

void CalcDiscreteVariableUpdates (const Context< T > &context, const EventCollection< DiscreteUpdateEvent< T >> &events, DiscreteValues< T > *discrete_state) const
This method is the public entry point for dispatching all discrete variable update event handlers. More...

void CalcDiscreteVariableUpdates (const Context< T > &context, DiscreteValues< T > *discrete_state) const
This method forces a discrete update on the system given a context, and the updated discrete state is stored in discrete_state. More...

void CalcUnrestrictedUpdate (const Context< T > &context, const EventCollection< UnrestrictedUpdateEvent< T >> &events, State< T > *state) const
This method is the public entry point for dispatching all unrestricted update event handlers. More...

void CalcUnrestrictedUpdate (const Context< T > &context, State< T > *state) const
This method forces an unrestricted update on the system given a context, and the updated state is stored in discrete_state. More...

CalcNextUpdateTime (const Context< T > &context, CompositeEventCollection< T > *events) const
This method is called by a Simulator during its calculation of the size of the next continuous step to attempt. More...

void GetPerStepEvents (const Context< T > &context, CompositeEventCollection< T > *events) const
This method is called by Simulator::Initialize() to gather all update and publish events that are to be handled in StepTo() at the point before Simulator integrates continuous state. More...

void GetInitializationEvents (const Context< T > &context, CompositeEventCollection< T > *events) const
This method is called by Simulator::Initialize() to gather all update and publish events that need to be handled at initialization before the simulator starts integration. More...

optional< typename Event< T >::PeriodicAttribute > GetUniquePeriodicDiscreteUpdateAttribute () const
Gets whether there exists a unique periodic attribute that triggers one or more discrete update events (and, if so, returns that unique periodic attribute). More...

std::map< typename Event< T >::PeriodicAttribute, std::vector< const Event< T > * >, PeriodicAttributeComparator< T > > GetPeriodicEvents () const
Gets all periodic triggered events for a system. More...

void CalcOutput (const Context< T > &context, SystemOutput< T > *outputs) const
Utility method that computes for every output port i the value y(i) that should result from the current contents of the given Context. More...

CalcPotentialEnergy (const Context< T > &context) const
Calculates and returns the potential energy current stored in the configuration provided in context. More...

CalcKineticEnergy (const Context< T > &context) const
Calculates and returns the kinetic energy currently present in the motion provided in the given Context. More...

CalcConservativePower (const Context< T > &context) const
Calculates and returns the rate at which mechanical energy is being converted from potential energy to kinetic energy by this system in the given Context. More...

CalcNonConservativePower (const Context< T > &context) const
Calculates and returns the rate at which mechanical energy is being generated (positive) or dissipated (negative) other than by conversion between potential and kinetic energy (in the given Context). More...

void MapVelocityToQDot (const Context< T > &context, const VectorBase< T > &generalized_velocity, VectorBase< T > *qdot) const
Transforms a given generalized velocity v to the time derivative qdot of the generalized configuration q taken from the supplied Context. More...

void MapVelocityToQDot (const Context< T > &context, const Eigen::Ref< const VectorX< T >> &generalized_velocity, VectorBase< T > *qdot) const
Transforms the given generalized velocity to the time derivative of generalized configuration. More...

void MapQDotToVelocity (const Context< T > &context, const VectorBase< T > &qdot, VectorBase< T > *generalized_velocity) const
Transforms the time derivative qdot of the generalized configuration q to generalized velocities v. More...

void MapQDotToVelocity (const Context< T > &context, const Eigen::Ref< const VectorX< T >> &qdot, VectorBase< T > *generalized_velocity) const
Transforms the given time derivative qdot of generalized configuration q to generalized velocity v. More...

void set_name (const std::string &name)
Sets the name of the system. More...

std::string get_name () const
Returns the name last supplied to set_name(), or empty if set_name() was never called. More...

std::string GetMemoryObjectName () const
Returns a name for this System based on a stringification of its type name and memory address. More...

void GetPath (std::stringstream *output) const
Writes the full path of this System in the tree of Systems to output. More...

std::string GetPath () const

int get_num_input_ports () const
Returns the number of input ports of the system. More...

int get_num_output_ports () const
Returns the number of output ports of the system. More...

const InputPortDescriptor< T > & get_input_port (int port_index) const
Returns the descriptor of the input port at index port_index. More...

const OutputPort< T > & get_output_port (int port_index) const
Returns the output port at index port_index. More...

int get_num_constraints () const
Returns the number of constraints specified for the system. More...

const SystemConstraint< T > & get_constraint (SystemConstraintIndex constraint_index) const
Returns the constraint at index constraint_index. More...

bool CheckSystemConstraintsSatisfied (const Context< T > &context, double tol) const
Returns true if context satisfies all of the registered SystemConstraints with tolerance tol. More...

int get_num_total_inputs () const
Returns the total dimension of all of the input ports (as if they were muxed). More...

int get_num_total_outputs () const
Returns the total dimension of all of the output ports (as if they were muxed). More...

void CheckValidOutput (const SystemOutput< T > *output) const
Checks that output is consistent with the number and size of output ports declared by the system. More...

template<typename T1 = T>
void CheckValidContext (const Context< T1 > &context) const
Checks that context is consistent for this System template. More...

VectorX< T > CopyContinuousStateVector (const Context< T > &context) const
Returns a copy of the continuous state vector xc into an Eigen vector. More...

void set_parent (const detail::InputPortEvaluatorInterface< T > *parent)
Declares that parent is the immediately enclosing Diagram. More...

std::string GetGraphvizString () const
Returns a Graphviz string describing this System. More...

int64_t GetGraphvizId () const
Returns an opaque integer that uniquely identifies this system in the Graphviz output. More...

void FixInputPortsFrom (const System< double > &other_system, const Context< double > &other_context, Context< T > *target_context) const
Fixes all of the input ports in target_context to their current values in other_context, as evaluated by other_system. More...

const SystemScalarConverterget_system_scalar_converter () const
(Advanced) Returns the SystemScalarConverter for this object. More...

std::unique_ptr< System< AutoDiffXd > > ToAutoDiffXd () const
Creates a deep copy of this System, transmogrified to use the autodiff scalar type, with a dynamic-sized vector of partial derivatives. More...

std::unique_ptr< System< AutoDiffXd > > ToAutoDiffXdMaybe () const
Creates a deep copy of this system exactly like ToAutoDiffXd(), but returns nullptr if this System does not support autodiff, instead of throwing an exception. More...

std::unique_ptr< System< symbolic::Expression > > ToSymbolic () const
Creates a deep copy of this System, transmogrified to use the symbolic scalar type. More...

std::unique_ptr< System< symbolic::Expression > > ToSymbolicMaybe () const
Creates a deep copy of this system exactly like ToSymbolic(), but returns nullptr if this System does not support symbolic, instead of throwing an exception. More...

## Static Public Member Functions

static T JointLimitForce (const DrakeJoint &joint, const T &position, const T &velocity)
Computes the force exerted by the stop when a joint hits its limit, using a linear stiffness model. More...

Static Public Member Functions inherited from System< T >
template<template< typename > class S = ::drake::systems::System>
static std::unique_ptr< S< AutoDiffXd > > ToAutoDiffXd (const S< T > &from)
Creates a deep copy of from, transmogrified to use the autodiff scalar type, with a dynamic-sized vector of partial derivatives. More...

template<template< typename > class S = ::drake::systems::System>
static std::unique_ptr< S< symbolic::Expression > > ToSymbolic (const S< T > &from)
Creates a deep copy of from, transmogrified to use the symbolic scalar type. More...

## Protected Member Functions

VectorX< T > EvaluateActuatorInputs (const Context< T > &context) const

std::unique_ptr< ContinuousState< T > > AllocateContinuousState () const override
Returns a ContinuousState used to implement both CreateDefaultContext and AllocateTimeDerivatives. More...

std::unique_ptr< DiscreteValues< T > > AllocateDiscreteState () const override
Reserves the discrete state as required by CreateDefaultContext. More...

void DoCalcTimeDerivatives (const Context< T > &context, ContinuousState< T > *derivatives) const override
Override this if you have any continuous state variables xc in your concrete System to calculate their time derivatives. More...

void DoCalcDiscreteVariableUpdates (const Context< T > &context, const std::vector< const DiscreteUpdateEvent< double > * > &, DiscreteValues< T > *updates) const override

optional< boolDoHasDirectFeedthrough (int, int) const override
Returns true if there is direct-feedthrough from the given input_port to the given output_port, false if there is not direct-feedthrough, or nullopt if unknown (in which case SystemSymbolicInspector will attempt to measure the feedthrough using symbolic form). More...

DoCalcPotentialEnergy (const Context< T > &) const override
Override this method for physical systems to calculate the potential energy currently stored in the configuration provided in the given Context. More...

DoCalcKineticEnergy (const Context< T > &) const override
Override this method for physical systems to calculate the kinetic energy currently present in the motion provided in the given Context. More...

DoCalcConservativePower (const Context< T > &) const override
Override this method to return the rate at which mechanical energy is being converted from potential energy to kinetic energy by this system in the given Context. More...

DoCalcNonConservativePower (const Context< T > &) const override
Override this method to return the rate at which mechanical energy is being generated (positive) or dissipated (negative) other than by conversion between potential and kinetic energy (in the given Context). More...

void DoMapVelocityToQDot (const Context< T > &context, const Eigen::Ref< const VectorX< T >> &generalized_velocity, VectorBase< T > *positions_derivative) const override
Provides the substantive implementation of MapVelocityToQDot(). More...

void DoMapQDotToVelocity (const Context< T > &context, const Eigen::Ref< const VectorX< T >> &configuration_dot, VectorBase< T > *generalized_velocity) const override
Provides the substantive implementation of MapQDotToVelocity(). More...

Protected Member Functions inherited from LeafSystem< T >
LeafSystem ()
Default constructor that declares no inputs, outputs, state, parameters, events, nor scalar-type conversion support (AutoDiff, etc.). More...

LeafSystem (SystemScalarConverter converter)
Constructor that declares no inputs, outputs, state, parameters, or events, but allows subclasses to declare scalar-type conversion support (AutoDiff, etc.). More...

virtual std::unique_ptr< LeafContext< T > > DoMakeContext () const
Provides a new instance of the leaf context for this system. More...

DoEvaluateWitness (const Context< T > &context, const WitnessFunction< T > &witness_func) const final
Derived classes will implement this method to evaluate a witness function at the given context. More...

void AddTriggeredWitnessFunctionToCompositeEventCollection (const WitnessFunction< T > &witness_func, CompositeEventCollection< T > *events) const final
Add witness_func to events. More...

void DoCalcNextUpdateTime (const Context< T > &context, CompositeEventCollection< T > *events, T *time) const override
Computes the next update time based on the configured periodic events, for scalar types that are arithmetic, or aborts for scalar types that are not arithmetic. More...

BasicVector< T > * DoAllocateInputVector (const InputPortDescriptor< T > &descriptor) const override
Allocates a vector that is suitable as an input value for descriptor. More...

AbstractValueDoAllocateInputAbstract (const InputPortDescriptor< T > &descriptor) const override
Allocates an AbstractValue suitable as an input value for descriptor. More...

void GetGraphvizFragment (std::stringstream *dot) const override
Emits a graphviz fragment for this System. More...

void GetGraphvizInputPortToken (const InputPortDescriptor< T > &port, std::stringstream *dot) const final
Appends a fragment to the dot stream identifying the graphviz node representing port. More...

void GetGraphvizOutputPortToken (const OutputPort< T > &port, std::stringstream *dot) const final
Appends a fragment to the dot stream identifying the graphviz node representing port. More...

virtual std::unique_ptr< AbstractValuesAllocateAbstractState () const
Reserves the abstract state as required by CreateDefaultContext. More...

virtual std::unique_ptr< Parameters< T > > AllocateParameters () const
Reserves the parameters as required by CreateDefaultContext. More...

int DeclareNumericParameter (const BasicVector< T > &model_vector)
Declares a numeric parameter using the given model_vector. More...

template<template< typename > class U = BasicVector>
const U< T > & GetNumericParameter (const Context< T > &context, int index) const
Extracts the numeric parameters of type U from the context at index. More...

template<template< typename > class U = BasicVector>
U< T > & GetMutableNumericParameter (Context< T > *context, int index) const
Extracts the numeric parameters of type U from the context at index. More...

template<typename EventType >
void DeclarePeriodicEvent (double period_sec, double offset_sec)
Declares that this System has a simple, fixed-period event specified with no custom callback function, and its attribute field contains an Event<T>::PeriodicAttribute constructed from the specified period_sec and offset_sec. More...

template<typename EventType >
void DeclarePeriodicEvent (double period_sec, double offset_sec, const EventType &event)
Declares that this System has a simple, fixed-period event specified by event. More...

void DeclarePeriodicDiscreteUpdate (double period_sec, double offset_sec=0)
Declares a periodic discrete update event with period = period_sec and offset = offset_sec. More...

void DeclarePeriodicUnrestrictedUpdate (double period_sec, double offset_sec=0)
Declares a periodic unrestricted update event with period = period_sec and offset = offset_sec. More...

void DeclarePeriodicPublish (double period_sec, double offset_sec=0)
Declares a periodic publish event with period = period_sec and offset = offset_sec. More...

template<typename EventType >
void DeclarePerStepEvent (const EventType &event)
Declares a per-step event using event, which is deep copied (the copy is maintained by this). More...

template<typename EventType >
void DeclareInitializationEvent (const EventType &event)
Declares an initialization event by deep copying event and storing it internally. More...

void DeclareContinuousState (int num_state_variables)
Declares that this System should reserve continuous state with num_state_variables state variables, which have no second-order structure. More...

void DeclareContinuousState (int num_q, int num_v, int num_z)
Declares that this System should reserve continuous state with num_q generalized positions, num_v generalized velocities, and num_z miscellaneous state variables. More...

void DeclareContinuousState (const BasicVector< T > &model_vector)
Declares that this System should reserve continuous state with model_vector.size() miscellaneous state variables, stored in a vector Cloned from model_vector. More...

void DeclareContinuousState (const BasicVector< T > &model_vector, int num_q, int num_v, int num_z)
Declares that this System should reserve continuous state with num_q generalized positions, num_v generalized velocities, and num_z miscellaneous state variables, stored in a vector Cloned from model_vector. More...

void DeclareContinuousState (std::unique_ptr< BasicVector< T >> model_vector, int num_q, int num_v, int num_z)
Declares that this System should reserve continuous state with num_q generalized positions, num_v generalized velocities, and num_z miscellaneous state variables, stored in the a vector Cloned from model_vector. More...

void DeclareDiscreteState (int num_state_variables)
Declares that this System should reserve discrete state with num_state_variables state variables. More...

int DeclareAbstractState (std::unique_ptr< AbstractValue > abstract_state)
Declares an abstract state. More...

template<class MySystem >
SystemConstraintIndex DeclareEqualityConstraint (void(MySystem::*calc)(const Context< T > &, VectorX< T > *) const, int count, const std::string &description)
Declares a system constraint of the form f(context) = 0 by specifying a member function to use to calculate the (VectorX) constraint value with a signature: More...

SystemConstraintIndex DeclareEqualityConstraint (typename SystemConstraint< T >::CalcCallback calc, int count, const std::string &description)
Declares a system constraint of the form f(context) = 0 by specifying a std::function to use to calculate the (Vector) constraint value with a signature: More...

template<class MySystem >
SystemConstraintIndex DeclareInequalityConstraint (void(MySystem::*calc)(const Context< T > &, VectorX< T > *) const, int count, const std::string &description)
Declares a system constraint of the form f(context) ≥ 0 by specifying a member function to use to calculate the (VectorX) constraint value with a signature: More...

SystemConstraintIndex DeclareInequalityConstraint (typename SystemConstraint< T >::CalcCallback calc, int count, const std::string &description)
Declares a system constraint of the form f(context) ≥ 0 by specifying a std::function to use to calculate the (Vector) constraint value with a signature: More...

virtual void DoPublish (const Context< T > &context, const std::vector< const PublishEvent< T > * > &events) const
Derived-class event handler for all simultaneous publish events in events. More...

virtual void DoCalcDiscreteVariableUpdates (const Context< T > &context, const std::vector< const DiscreteUpdateEvent< T > * > &events, DiscreteValues< T > *discrete_state) const
Derived-class event handler for all simultaneous discrete update events. More...

virtual void DoCalcUnrestrictedUpdate (const Context< T > &context, const std::vector< const UnrestrictedUpdateEvent< T > * > &events, State< T > *state) const
Derived-class event handler for all simultaneous unrestricted update events. More...

const InputPortDescriptor< T > & DeclareVectorInputPort (const BasicVector< T > &model_vector, optional< RandomDistribution > random_type=nullopt)
Declares a vector-valued input port using the given model_vector. More...

const InputPortDescriptor< T > & DeclareAbstractInputPort (const AbstractValue &model_value)
Declares an abstract-valued input port using the given model_value. More...

template<class MySystem , typename BasicVectorSubtype >
const OutputPort< T > & DeclareVectorOutputPort (const BasicVectorSubtype &model_vector, void(MySystem::*calc)(const Context< T > &, BasicVectorSubtype *) const)
Declares a vector-valued output port by specifying (1) a model vector of type BasicVectorSubtype derived from BasicVector and initialized to the correct size and desired initial value, and (2) a calculator function that is a class member function (method) with signature: More...

template<class MySystem , typename BasicVectorSubtype >
const OutputPort< T > & DeclareVectorOutputPort (void(MySystem::*calc)(const Context< T > &, BasicVectorSubtype *) const)
Declares a vector-valued output port by specifying only a calculator function that is a class member function (method) with signature: More...

const OutputPort< T > & DeclareVectorOutputPort (const BasicVector< T > &model_vector, typename LeafOutputPort< T >::CalcVectorCallback vector_calc_function)
(Advanced) Declares a vector-valued output port using the given model_vector and a function for calculating the port's value at runtime. More...

template<class MySystem , typename OutputType >
const OutputPort< T > & DeclareAbstractOutputPort (const OutputType &model_value, void(MySystem::*calc)(const Context< T > &, OutputType *) const)
Declares an abstract-valued output port by specifying a model value of concrete type OutputType and a calculator function that is a class member function (method) with signature: More...

template<class MySystem , typename OutputType >
const OutputPort< T > & DeclareAbstractOutputPort (void(MySystem::*calc)(const Context< T > &, OutputType *) const)
Declares an abstract-valued output port by specifying only a calculator function that is a class member function (method) with signature: More...

template<class MySystem , typename OutputType >
const OutputPort< T > & DeclareAbstractOutputPort (OutputType(MySystem::*make)(const Context< T > &) const, void(MySystem::*calc)(const Context< T > &, OutputType *) const)
Declares an abstract-valued output port by specifying member functions to use both for the allocator and calculator. More...

template<class MySystem , typename OutputType >
const OutputPort< T > & DeclareAbstractOutputPort (OutputType(MySystem::*make)() const, void(MySystem::*calc)(const Context< T > &, OutputType *) const)
Declares an abstract-valued output port by specifying member functions to use both for the allocator and calculator. More...

const OutputPort< T > & DeclareAbstractOutputPort (typename LeafOutputPort< T >::AllocCallback alloc_function, typename LeafOutputPort< T >::CalcCallback calc_function)
(Advanced) Declares an abstract-valued output port using the given allocator and calculator functions provided in their most generic forms. More...

Protected Member Functions inherited from System< T >
virtual void DoGetWitnessFunctions (const Context< T > &, std::vector< const WitnessFunction< T > * > *) const
Derived classes can override this method to provide witness functions active at the beginning of a continuous time interval. More...

SystemConstraintIndex AddConstraint (std::unique_ptr< SystemConstraint< T >> constraint)
Adds an already-created constraint to the list of constraints for this System. More...

const EventCollection< PublishEvent< T > > & get_forced_publish_events () const

const EventCollection< DiscreteUpdateEvent< T > > & get_forced_discrete_update_events () const

const EventCollection< UnrestrictedUpdateEvent< T > > & get_forced_unrestricted_update_events () const

void set_forced_publish_events (std::unique_ptr< EventCollection< PublishEvent< T >>> forced)

void set_forced_discrete_update_events (std::unique_ptr< EventCollection< DiscreteUpdateEvent< T >>> forced)

void set_forced_unrestricted_update_events (std::unique_ptr< EventCollection< UnrestrictedUpdateEvent< T >>> forced)

System (SystemScalarConverter converter)
Constructs an empty System base class object, possibly supporting scalar-type conversion support (AutoDiff, etc.) using converter. More...

const InputPortDescriptor< T > & DeclareInputPort (PortDataType type, int size, optional< RandomDistribution > random_type=nullopt)
Adds a port with the specified type and size to the input topology. More...

const InputPortDescriptor< T > & DeclareAbstractInputPort ()
Adds an abstract-valued port to the input topology. More...

void CreateOutputPort (std::unique_ptr< OutputPort< T >> port)
Adds an already-created output port to this System. More...

virtual int do_get_num_constraint_equations (const Context< T > &context) const
Gets the number of constraint equations for this system from the given context. More...

virtual Eigen::VectorXd DoEvalConstraintEquations (const Context< T > &context) const
Evaluates the constraint equations for the system at the generalized coordinates and generalized velocity specified by the context. More...

virtual Eigen::VectorXd DoEvalConstraintEquationsDot (const Context< T > &context) const
Computes the time derivative of each constraint equation, evaluated at the generalized coordinates and generalized velocity specified by the context. More...

virtual Eigen::VectorXd DoCalcVelocityChangeFromConstraintImpulses (const Context< T > &context, const Eigen::MatrixXd &J, const Eigen::VectorXd &lambda) const
Computes the change in velocity from applying the given constraint forces to the system at the given context. More...

virtual double DoCalcConstraintErrorNorm (const Context< T > &context, const Eigen::VectorXd &error) const
Computes the norm of the constraint error. More...

Eigen::VectorBlock< VectorX< T > > GetMutableOutputVector (SystemOutput< T > *output, int port_index) const
Returns a mutable Eigen expression for a vector valued output port with index port_index in this system. More...

void EvalInputPort (const Context< T > &context, int port_index) const
Causes an InputPortValue in the context to become up-to-date, delegating to the parent Diagram if necessary. More...

## Detailed Description

### template<typename T> class drake::systems::RigidBodyPlant< T >

This class provides a System interface around a multibody dynamics model of the world represented by a RigidBodyTree.

The RigidBodyPlant provides a number of input and output ports. The number and types of port accessors depends on the number of model instances within the RigidBodyTree with actuators. The following lists the accessors for obtaining the input and output ports of the RigidBodyPlant. These accessors are typically used when "wiring up" a RigidBodyPlant within a Diagram using DiagramBuilder. See, for example, DiagramBuilder::Connect(), DiagramBuilder::ExportInput(), and DiagramBuilder::ExportOutput().

Plant-Centric Port Accessors:

• actuator_command_input_port(): Contains the command vector for the RigidBodyTree's actuators. This method can only be called when there is only one model instance in the RigidBodyTree, as determined by get_num_model_instances(), and this model instance has at least one actuator. The size of this vector equals the number of RigidBodyActuator's in the RigidBodyTree. Each RigidBodyActuator maps to a single-DOF joint (currently actuation cannot be applied to multiple-DOF joints). The units of the actuation are the same as the units of the generalized force on the joint. In addition, actuators allow for a gear box reduction factor and for actuation limits which are only used by controllers; the RigidBodyPlant does not apply these limits. The gear box factor effectively is a multiplier on the input actuation to the RigidBodyPlant.
• state_output_port(): A vector-valued port containing the state vector, x, of the system. This is useful for downstream systems that require x, which includes DrakeVisualizer. The state vector, x, consists of generalized positions followed by generalized velocities. Semantics of x can be obtained using the following methods:
• kinematics_results_output_port(): An abstract-valued port containing a KinematicsResults object allowing access to the results from kinematics computations for each RigidBody in the RigidBodyTree.
• contact_results_output_port(): An abstract-valued port containing a ContactsResults object allowing access to the results from contact computations.

Model-Instance-Centric Port Accessors:

The RigidBodyPlant's state consists of a vector containing the generalized positions followed by the generalized velocities of the system. This state is applied to a RigidBodyTree, which is a multibody model that consists of a set of rigid bodies connected through joints in a tree structure. Bodies may have a collision model, in which case, collisions are considered. In addition, the model may contain loop constraints described by RigidBodyLoop instances in the multibody model. Even though loop constraints are a particular case of holonomic constraints, general holonomic constraints are not yet supported.

The system dynamics is given by the set of multibody equations written in generalized coordinates including loop joints as a set of holonomic constraints like so:

  H(q) * vdot + C(q, v) = tau_actuators + tau_constraints.


where q is the vector of generalized coordinates (or positions), v is the vector of generalized velocities, C includes the velocity-dependent Coriolis and gyroscopic forces, tau_actuators is the vector of externally applied generalized forces and finally tau_constraints is the vector of generalized forces due to constraints. tau_constraints is computed as

  tau_constraints = -J^T * lambda


where lambda is the vector of Lagrange multipliers representing the constraint forces and J is the constraint Jacobian. The time derivative of the generalized coordinates is then obtained from the generalized velocities as

  qdot = N(q) * v


where N(q) is a transformation matrix only dependent on the positions.

Template Parameters
 T The scalar type. Must be a valid Eigen scalar.

## Constructor & Destructor Documentation

 RigidBodyPlant ( const RigidBodyPlant< T > & )
delete
 RigidBodyPlant ( RigidBodyPlant< T > && )
delete
 RigidBodyPlant ( std::unique_ptr< const RigidBodyTree< T >> tree, double timestep = 0.0 )
explicit

Instantiates a RigidBodyPlant from a Multi-Body Dynamics (MBD) model of the world in tree.

tree must not be nullptr.

Parameters
 [in] tree the dynamic model to use with this plant. [in] timestep a non-negative value specifying the update period of the model; 0.0 implies continuous-time dynamics with derivatives, and values > 0.0 result in discrete-time dynamics implementing a time-stepping approximation to the dynamics. Default: 0.0.

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 ~RigidBodyPlant ( )
override

## Member Function Documentation

 const InputPortDescriptor& actuator_command_input_port ( ) const
inline

Returns a descriptor of the actuator command input port.

This method can only be called when there is only one model instance in the RigidBodyTree. Otherwise, a std::runtime_error will be thrown. It returns the same port as model_instance_actuator_command_input_port() using input parameter RigidBodyTreeConstants::kFirstNonWorldModelInstanceId.

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 std::unique_ptr< ContinuousState< T > > AllocateContinuousState ( ) const
overrideprotectedvirtual

Returns a ContinuousState used to implement both CreateDefaultContext and AllocateTimeDerivatives.

Allocates the state configured with DeclareContinuousState, or none by default. Systems with continuous state variables may override, but must ensure the ContinuousState vector is a subclass of BasicVector.

Reimplemented from LeafSystem< T >.

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 std::unique_ptr< DiscreteValues< T > > AllocateDiscreteState ( ) const
overrideprotectedvirtual

Reserves the discrete state as required by CreateDefaultContext.

By default, reserves no state. Systems with discrete state should override.

Reimplemented from LeafSystem< T >.

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 const OutputPort& contact_results_output_port ( ) const
inline

Returns the ContactResults output port.

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 T DoCalcConservativePower ( const Context< T > & context ) const
inlineoverrideprotectedvirtual

Override this method to return the rate at which mechanical energy is being converted from potential energy to kinetic energy by this system in the given Context.

This quantity must be positive when potential energy is decreasing. Power is in watts (J/s).

By default, returns zero. Continuous, physical systems should override. You may assume that context has already been validated before it is passed to you here.

Reimplemented from System< T >.

 void DoCalcDiscreteVariableUpdates ( const Context< T > & context, const std::vector< const DiscreteUpdateEvent< double > * > & , DiscreteValues< T > * updates ) const
overrideprotected

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 T DoCalcKineticEnergy ( const Context< T > & context ) const
inlineoverrideprotectedvirtual

Override this method for physical systems to calculate the kinetic energy currently present in the motion provided in the given Context.

The default implementation returns 0 which is correct for non-physical systems. You may assume that context has already been validated before it is passed to you here.

Reimplemented from System< T >.

 T DoCalcNonConservativePower ( const Context< T > & context ) const
inlineoverrideprotectedvirtual

Override this method to return the rate at which mechanical energy is being generated (positive) or dissipated (negative) other than by conversion between potential and kinetic energy (in the given Context).

Integrating this quantity yields work W, and the total energy E=PE+KE-W should be conserved by any physically-correct model, to within integration accuracy of W. Power is in watts (J/s). (Watts are abbreviated W but not to be confused with work!) This method is meaningful only for physical systems; others return zero.

By default, returns zero. Continuous, physical systems should override. You may assume that context has already been validated before it is passed to you here.

Reimplemented from System< T >.

 T DoCalcPotentialEnergy ( const Context< T > & context ) const
inlineoverrideprotectedvirtual

Override this method for physical systems to calculate the potential energy currently stored in the configuration provided in the given Context.

The default implementation returns 0 which is correct for non-physical systems. You may assume that context has already been validated before it is passed to you here.

Reimplemented from System< T >.

 void DoCalcTimeDerivatives ( const Context< T > & context, ContinuousState< T > * derivatives ) const
overrideprotectedvirtual

Override this if you have any continuous state variables xc in your concrete System to calculate their time derivatives.

The derivatives vector will correspond elementwise with the state vector Context.state.continuous_state.get_state(). Thus, if the state in the Context has second-order structure xc=[q,v,z], that same structure applies to the derivatives.

This method is called only from the public non-virtual CalcTimeDerivatives() which will already have error-checked the parameters so you don't have to. In particular, implementations may assume that the given Context is valid for this System; that the derivatives pointer is non-null, and that the referenced object has the same constituent structure as was produced by AllocateTimeDerivatives().

The default implementation does nothing if the derivatives vector is size zero and aborts otherwise.

Reimplemented from System< T >.

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 optional< bool > DoHasDirectFeedthrough ( int input_port, int output_port ) const
overrideprotectedvirtual

Returns true if there is direct-feedthrough from the given input_port to the given output_port, false if there is not direct-feedthrough, or nullopt if unknown (in which case SystemSymbolicInspector will attempt to measure the feedthrough using symbolic form).

By default, LeafSystem assumes there is direct feedthrough of values from every input to every output. This is a conservative assumption that ensures we detect and can prevent the formation of algebraic loops (implicit computations) in system Diagrams. Systems which do not have direct feedthrough may override that assumption in two ways:

• Override DoToSymbolic, allowing LeafSystem to infer the sparsity from the symbolic equations. This method is typically preferred for systems that have a symbolic form, but should be avoided in certain corner cases where fully descriptive symbolic analysis is impossible, e.g., when the symbolic form depends on C++ native conditionals. For additional discussion, consult the documentation for SystemSymbolicInspector.
• Override this function directly, reporting manual sparsity. This method is recommended when DoToSymbolic has not been implemented, or when creating the symbolic form is too computationally expensive, or when its output is not fully descriptive, as discussed above. Manually configured sparsity must be conservative: if there is any Context for which an input port is direct-feedthrough to an output port, this function must return either true or nullopt for those two ports.

Reimplemented from LeafSystem< T >.

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 void DoMapQDotToVelocity ( const Context< T > & context, const Eigen::Ref< const VectorX< T >> & qdot, VectorBase< T > * generalized_velocity ) const
overrideprotectedvirtual

Provides the substantive implementation of MapQDotToVelocity().

The default implementation uses the identity mapping, and correctly does nothing if the System does not have second-order state variables. It throws std::runtime_error if the generalized_velocity and qdot are not the same size, but that is not enough to guarantee that the default implementation is adequate. Child classes must override this function if qdot != v (even if they are the same size). This occurs, for example, if a joint uses roll-pitch-yaw rotation angles for orientation but angular velocity for rotational rate rather than rotation angle derivatives.

If you implement this method you are required to use no more than O(nq) time where nq is the size of qdot, so that the System can meet the performance guarantee made for the public interface, and you must also implement DoMapVelocityToQDot(). Implementations may assume that qdot has already been validated to be the same size as q in the given Context, and that generalized_velocity is non-null.

Reimplemented from System< T >.

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 void DoMapVelocityToQDot ( const Context< T > & context, const Eigen::Ref< const VectorX< T >> & generalized_velocity, VectorBase< T > * qdot ) const
overrideprotectedvirtual

Provides the substantive implementation of MapVelocityToQDot().

The default implementation uses the identity mapping, and correctly does nothing if the System does not have second-order state variables. It throws std::runtime_error if the generalized_velocity (v) and qdot are not the same size, but that is not enough to guarantee that the default implementation is adequate. Child classes must override this function if qdot != v (even if they are the same size). This occurs, for example, if a joint uses roll-pitch-yaw rotation angles for orientation but angular velocity for rotational rate rather than rotation angle derivatives.

If you implement this method you are required to use no more than O(nq) time where nq is the size of qdot, so that the System can meet the performance guarantee made for the public interface, and you must also implement DoMapQDotToVelocity(). Implementations may assume that generalized_velocity has already been validated to be the same size as v in the given Context, and that qdot is non-null.

Reimplemented from System< T >.

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 VectorX< T > EvaluateActuatorInputs ( const Context< T > & context ) const
protected

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 int FindInstancePositionIndexFromWorldIndex ( int model_instance_id, int world_position_index )

Returns the index into the output port for model_instance_id which corresponds to the world position index of world_position_index, or throws if the position index does not correspond to the model id.

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 int get_input_size ( ) const

Returns the size of the input vector to the system.

This equals the number of actuators.

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 int get_num_actuators ( ) const

Returns the number of actuators.

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 int get_num_actuators ( int model_instance_id ) const

Returns the number of actuators for a specific model instance.

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 int get_num_bodies ( ) const

Returns the number of bodies in the world.

 int get_num_model_instances ( ) const

Returns the number of model instances in the world, not including the world.

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 int get_num_positions ( ) const

Returns the number of generalized coordinates of the model.

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 int get_num_positions ( int model_instance_id ) const

Returns the number of generalized coordinates for a specific model instance.

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 int get_num_states ( ) const

Returns the size of the continuous state of the system which equals get_num_positions() plus get_num_velocities().

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 int get_num_states ( int model_instance_id ) const

Returns the size of the continuous state of a specific model instance which equals get_num_positions() plus get_num_velocities().

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 int get_num_velocities ( ) const

Returns the number of generalized velocities of the model.

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 int get_num_velocities ( int model_instance_id ) const

Returns the number of generalized velocities for a specific model instance.

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 int get_output_size ( ) const

Returns the size of the output vector of the system.

This equals the size of the continuous state vector.

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 const RigidBodyTree< T > & get_rigid_body_tree ( ) const

Returns a constant reference to the multibody dynamics model of the world.

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 double get_time_step ( ) const
inline

Get the time step used to construct the plant.

If the step is zero, the system is continuous. Otherwise, the step corresponds to the update rate (seconds per update).

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 Eigen::VectorBlock< const VectorX< T > > GetStateVector ( const Context< T > & context ) const

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 bool is_state_discrete ( ) const
inline

Gets whether this system is modeled using discrete state.

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 T JointLimitForce ( const DrakeJoint & joint, const T & position, const T & velocity )
static

Computes the force exerted by the stop when a joint hits its limit, using a linear stiffness model.

Exposed for unit testing of the formula.

Linear stiffness formula (and definition of "dissipation") from: https://simtk.org/api_docs/simbody/latest/classSimTK_1_1Force_1_1MobilityLinearStop.html#details

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 const OutputPort& kinematics_results_output_port ( ) const
inline

Returns the KinematicsResults output port.

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 const InputPortDescriptor< T > & model_instance_actuator_command_input_port ( int model_instance_id ) const

Returns a descriptor of the input port for a specific model instance.

This method can only be called when this class is instantiated with constructor parameter export_model_instance_centric_ports equal to true.

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 bool model_instance_has_actuators ( int model_instance_id ) const

Returns true if and only if the model instance with the provided model_instance_id has actuators.

This is useful when trying to determine whether it's safe to call model_instance_actuator_command_input_port().

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 const OutputPort< T > & model_instance_state_output_port ( int model_instance_id ) const

Returns he output port containing the state of a particular model with instance ID equal to model_instance_id.

Throws a std::runtime_error if model_instance_id does not exist. This method can only be called when this class is instantiated with constructor parameter export_model_instance_centric_ports equal to true.

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 RigidBodyPlant& operator= ( RigidBodyPlant< T > && )
delete
 RigidBodyPlant& operator= ( const RigidBodyPlant< T > & )
delete
 void set_friction_contact_parameters ( double static_friction_coef, double dynamic_friction_coef, double v_stiction_tolerance )

Sets only the parameters for friction contact.

This is a convenience function to allow for more targeted parameter tuning.

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 void set_normal_contact_parameters ( double penetration_stiffness, double dissipation )

Sets only the parameters for normal contact.

This is a convenience function to allow for more targeted parameter tuning.

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 void set_position ( Context< T > * context, int position_index, T position ) const

Sets the generalized coordinate position_index to the value position.

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 void set_state_vector ( Context< T > * context, const Eigen::Ref< const VectorX< T >> x ) const

Sets the continuous state vector of the system to be x.

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 void set_state_vector ( State< T > * state, const Eigen::Ref< const VectorX< T >> x ) const

Sets the continuous state vector of the system to be x.

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 void set_velocity ( Context< T > * context, int velocity_index, T velocity ) const

Sets the generalized velocity velocity_index to the value velocity.

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 void SetDefaultState ( const Context< T > & , State< T > * state ) const
inlineoverridevirtual

Sets the state in context so that generalized positions and velocities are zero.

For quaternion based joints the quaternion is set to be the identity (or equivalently a zero rotation).

Implements System< T >.

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 const OutputPort& state_output_port ( ) const
inline

Returns the plant-centric state output port.

The size of this port is equal to get_num_states().

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