Constraint Class Reference

A constraint is a mathematical model that constrain the movement between two arbitrary bodies in a dynamic simulation. More...

#include <Constraint.hpp>

Inherits StateData.

Classes
struct	Limit
	Definition of a limit for one single degree of freedom. More...
struct	SpringParams
	Parameters for a spring. More...

Public Types
enum	ConstraintType {   Fixed , Prismatic , Revolute , Universal ,   Spherical , Piston , PrismaticRotoid , PrismaticUniversal ,   Free }
	The different constraint types. More...
typedef rw::core::Ptr< Constraint >	Ptr
	smart pointer type to this class

Public Member Functions
	Constraint (const std::string &name, const ConstraintType &type, Body *b1, Body *b2)
	Construct new constraint. More...
virtual	~Constraint ()
	Destructor.
ConstraintType	getType () const
	Get the type of constraint. More...
Body *	getBody1 () const
	Get a pointer to Body 1. More...
Body *	getBody2 () const
	Get a pointer to Body 2. More...
size_t	getDOF () const
	Get the degrees of freedom of the constraint. More...
size_t	getDOFLinear () const
	Get the linear degrees of freedom of the constraint. More...
size_t	getDOFAngular () const
	Get the angular degrees of freedom of the constraint. More...
rw::math::Transform3D	getTransform () const
	Get the transform of the constraint, relative to the parents body frame. More...
void	setTransform (const rw::math::Transform3D<> &parentTconstraint)
	Set the transform of the constraint, relative to the parents body frame. More...
SpringParams	getSpringParams () const
	Get the spring parameters. More...
void	setSpringParams (const SpringParams &params)
	Set spring parameters. More...
Limit	getLimit (std::size_t i) const
	Get limit information. More...
void	setLimit (std::size_t i, const Limit &limit)
	Set limit. More...
Public Member Functions inherited from StateData
virtual	~StateData ()
	destructor
int	getID () const
	An integer ID for the StateData. More...
const std::string &	getName () const
	The name of the state data. More...
int	size () const
	The number of doubles allocated by this StateData in each State object. More...
const double *	getData (const rw::kinematics::State &state) const
	An array of length size() containing the values for the state data. More...
double *	getData (rw::kinematics::State &state)
	An array of length size() containing the values for the state data. More...
void	setData (rw::kinematics::State &state, const double *vals) const
	Assign for state data the size() of values of the array vals. More...
void	setData (rw::kinematics::State &state, const std::vector< double > &vals) const
	Assign for state data the size() of values of the array vals. More...
void	setData (rw::kinematics::State &state, const double &val) const
	Assign for state data the size() of values of the array vals. More...
bool	hasCache () const
	Check is state data includes a cache. More...
rw::core::Ptr< rw::kinematics::StateCache >	getCache (const rw::kinematics::State &state) const
	Get the cache. More...
rw::core::Ptr< rw::kinematics::StateCache >	getCache (rw::kinematics::State &state)
	Get the cache. . More...
rw::core::Ptr< rw::kinematics::StateCache >	getDefaultCache ()
	Get default cache. More...
void	setCache (rw::core::Ptr< rw::kinematics::StateCache > cache, rw::kinematics::State &state)
	Set the cache values. More...
class rw::kinematics::StateStructure *	getStateStructure ()
	Get the state structure. More...
bool	operator== (const StateData &rhs)
	Compares the state data to see if they are the same Checks the ID, name and which statetrucure they belong to. More...
bool	operator!= (const StateData &rhs)
	Check if not equal. More...
	StateData (int size, const std::string &name)
	A state with size number of doubles in the State vector. More...
	StateData (int size, const std::string &name, rw::core::Ptr< rw::kinematics::StateCache > cache)
	A state with size number of doubles in the State vector. More...

Static Public Member Functions
static bool	toConstraintType (const std::string &string, ConstraintType &type)
	Convert a string to a ConstraintType. More...

Detailed Description

A constraint is a mathematical model that constrain the movement between two arbitrary bodies in a dynamic simulation.

For a device the Link and Joint types should be used to specify the constraints.

The Constraint type can however be used between any two bodies. For instance between two free bodies, or between a free body and a link of a device.

All functions in this class are thread-safe. Only the transform of the constraint and the spring parameters can be changed after creation of the constraint.

Member Enumeration Documentation

ConstraintType

enum ConstraintType

The different constraint types.

Enumerator
Fixed	bodies will not be able to move relative to eachother (0 DOF).
Prismatic	bodies will be able to move in the z-direction only (1 DOF).
Revolute	bodies will be able to rotate around the z-direction only (1 DOF).
Universal	bodies will be able to both rotate around the x- and y- directions (2 DOF).
Spherical	bodies will be able to rotate relative to eachother, but not move linearly (3 DOF).
Piston	bodies will be able to translate and rotate around the z-axis (2 DOF).
PrismaticRotoid	bodies will be able to translate along the z-axis and rotate around the x-axis (2 DOF).
PrismaticUniversal	bodies will be able to translate along the z-axis and rotate around both the x- and y-axes (3 DOF).
Free	bodies are not constrained (6 DOF) - can be used for 6D springs.

Constructor & Destructor Documentation

Constraint()

Constraint	(	const std::string &	name,
		const ConstraintType &	type,
		Body *	b1,
		Body *	b2
	)

Construct new constraint.

Parameters

name	[in] a unique name identifying the constraint.
type	[in] the type of constraint.
b1	[in] the parent body to attach the constraint to.
b2	[in] the child body to attach the constraint to.

Member Function Documentation

getBody1()

Body* getBody1

(

)

const

Get a pointer to Body 1.

Returns

pointer to body 1.

getBody2()

Body* getBody2

(

)

const

Get a pointer to Body 2.

Returns

pointer to body 2.

getDOF()

size_t getDOF

(

)

const

Get the degrees of freedom of the constraint.

Returns

the degrees of freedom.

getDOFAngular()

size_t getDOFAngular

(

)

const

Get the angular degrees of freedom of the constraint.

Returns

the angular degrees of freedom.

getDOFLinear()

size_t getDOFLinear

(

)

const

Get the linear degrees of freedom of the constraint.

Returns

the linear degrees of freedom.

getLimit()

Limit getLimit

(

std::size_t

i

)

const

Get limit information.

Parameters

i	[in] the degree of freedom to get limit information for.

Returns

the limit.

getSpringParams()

SpringParams getSpringParams

(

)

const

Get the spring parameters.

Returns

SpringParams structure.

getTransform()

rw::math::Transform3D getTransform

(

)

const

Get the transform of the constraint, relative to the parents body frame.

Returns

the transform relative to the parent, \(\bf{T}_{parent}^{constraint}\).

getType()

ConstraintType getType

(

)

const

Get the type of constraint.

Returns

the ConstraintType

setLimit()

void setLimit	(	std::size_t	i,
		const Limit &	limit
	)

Set limit.

Parameters

i	[in] the degree of freedom to set limit information for.
limit	[in] the limit information.

setSpringParams()

void setSpringParams

(

const SpringParams &

params

)

Set spring parameters.

Parameters

params

[in] SpringParams structure.

setTransform()

void setTransform

(

const rw::math::Transform3D<> &

parentTconstraint

)

Set the transform of the constraint, relative to the parents body frame.

Parameters

parentTconstraint

[in] the transform relative to the parent, \(\bf{T}_{parent}^{constraint}\).

toConstraintType()

static bool toConstraintType ( const std::string &  string, ConstraintType &  type  )

static

Convert a string to a ConstraintType.

Parameters

string	[in] the string to convert.
type	[in/out] the result of the convertion.

Returns

true if string was converted, false otherwise.

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

• Constraint.hpp