AxiallySymmetricFreeBodyPlant< T > Class Template Reference

Detailed Description

template<typename T>
class drake::multibody::test::AxiallySymmetricFreeBodyPlant< T >

This plant models the free motion of a torque free body in space.

This body is axially symmetric with rotational inertia about its axis of revolution J and with a rotational inertia I about any axis perpendicular to its axis of revolution. This particular case has a nice closed form analytical solution which we have implemented in drake::multibody::benchmarks::free_body::FreeBody.

Template Parameters

T	The scalar type, which must be double.

#include <drake/multibody/test_utilities/floating_body_plant.h>

Public Member Functions
	AxiallySymmetricFreeBodyPlant (double mass, double I, double J, double g, double time_step=0.0)
	Constructor from known rotational inertia values. More...
	~AxiallySymmetricFreeBodyPlant ()
const MultibodyPlant< T > &	plant () const
	Returns the underlying MbP model. More...
std::unique_ptr< systems::Context< T > >	CreatePlantContext () const
	Returns a MbP context in which the free body frame B is coincident with the world frame W and the angular and translational velocities have a value as returned by get_default_initial_angular_velocity() and get_default_initial_translational_velocity(), respectively. More...
Vector3< T >	get_angular_velocity (const systems::Context< T > &context) const
	Returns the angular velocity w_WB stored in context of the free body B in the world frame W. More...
Vector3< T >	get_translational_velocity (const systems::Context< T > &context) const
	Returns the translational velocity v_WB stored in context of the free body B in the world frame W. More...
math::RigidTransform< T >	CalcPoseInWorldFrame (const systems::Context< T > &context) const
	Computes the pose X_WB of the body in the world frame. More...
SpatialVelocity< T >	CalcSpatialVelocityInWorldFrame (const systems::Context< T > &context) const
	Calculates V_WB, this body B's spatial velocity in the world frame W. More...
const RigidBody< T > &	body () const
	Returns a constant reference to the free body model of this plant. More...
Does not allow copy, move, or assignment
	AxiallySymmetricFreeBodyPlant (const AxiallySymmetricFreeBodyPlant &)=delete
AxiallySymmetricFreeBodyPlant &	operator= (const AxiallySymmetricFreeBodyPlant &)=delete
	AxiallySymmetricFreeBodyPlant (AxiallySymmetricFreeBodyPlant &&)=delete
AxiallySymmetricFreeBodyPlant &	operator= (AxiallySymmetricFreeBodyPlant &&)=delete

Static Public Member Functions
static Vector3< double >	get_default_initial_angular_velocity ()
	Returns the default value of the angular velocity set by default by SetDefaultState(). More...
static Vector3< double >	get_default_initial_translational_velocity ()
	Returns the default value of the translational velocity set by default by SetDefaultState(). More...

Constructor & Destructor Documentation

AxiallySymmetricFreeBodyPlant() [1/3]

AxiallySymmetricFreeBodyPlant ( const AxiallySymmetricFreeBodyPlant< T > &  )

delete

AxiallySymmetricFreeBodyPlant() [2/3]

AxiallySymmetricFreeBodyPlant ( AxiallySymmetricFreeBodyPlant< T > &&  )

delete

AxiallySymmetricFreeBodyPlant() [3/3]

AxiallySymmetricFreeBodyPlant	(	double	mass,
		double	I,
		double	J,
		double	g,
		double	time_step = 0.0
	)

Constructor from known rotational inertia values.

Rotational inertia values have units of kg⋅m².

Parameters

mass	The mass of the body.
I	rotational inertia about any axis perpendicular to the axis of revolution of the body.
J	rotational inertia about the axis of revolution of the body.
g	Acceleration of gravity. In this model if g > 0 the gravity vector points downward in the z-axis direction.
time_step	[optional] See MultibodyPlant::MultibodyPlant.

~AxiallySymmetricFreeBodyPlant()

~AxiallySymmetricFreeBodyPlant

(

)

Member Function Documentation

body()

const RigidBody<T>& body

(

)

const

Returns a constant reference to the free body model of this plant.

CalcPoseInWorldFrame()

math::RigidTransform<T> CalcPoseInWorldFrame

(

const systems::Context< T > &

context

)

const

Computes the pose X_WB of the body in the world frame.

CalcSpatialVelocityInWorldFrame()

SpatialVelocity<T> CalcSpatialVelocityInWorldFrame

(

const systems::Context< T > &

context

)

const

Calculates V_WB, this body B's spatial velocity in the world frame W.

Parameters

[in]

context

Contains the state of the model.

Return values

V_WB_W

this free-body B's spatial velocity in the world frame W, expressed in W (for point Bo, the body frame's origin).

CreatePlantContext()

std::unique_ptr<systems::Context<T> > CreatePlantContext

(

)

const

Returns a MbP context in which the free body frame B is coincident with the world frame W and the angular and translational velocities have a value as returned by get_default_initial_angular_velocity() and get_default_initial_translational_velocity(), respectively.

get_angular_velocity()

Vector3<T> get_angular_velocity

(

const systems::Context< T > &

context

)

const

Returns the angular velocity w_WB stored in context of the free body B in the world frame W.

get_default_initial_angular_velocity()

static Vector3<double> get_default_initial_angular_velocity ( )

static

Returns the default value of the angular velocity set by default by SetDefaultState().

Currently a non-zero value.

get_default_initial_translational_velocity()

static Vector3<double> get_default_initial_translational_velocity ( )

static

Returns the default value of the translational velocity set by default by SetDefaultState().

Currently a non-zero value.

get_translational_velocity()

Vector3<T> get_translational_velocity

(

const systems::Context< T > &

context

)

const

Returns the translational velocity v_WB stored in context of the free body B in the world frame W.

operator=() [1/2]

AxiallySymmetricFreeBodyPlant& operator= ( AxiallySymmetricFreeBodyPlant< T > &&  )

delete

operator=() [2/2]

AxiallySymmetricFreeBodyPlant& operator= ( const AxiallySymmetricFreeBodyPlant< T > &  )

delete

plant()

const MultibodyPlant<T>& plant

(

)

const

Returns the underlying MbP model.

---

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

• drake/multibody/test_utilities/floating_body_plant.h