Substance Class Reference

Physical substance definition, used for collision detection/treatment What we need is mu, slip and kp,kd parameter for the collision Definition of substance parameters:. More...

#include <substance.h>

List of all members.

Public Member Functions

Substance ()

Substance (float roughness, float slip, float hardness, float elasticity)

void setCollisionCallback (CollisionCallback func, void *userdata)

void toDefaultSubstance ()

void toMetal (float roughness)

very hard and elastic with slip roughness [0.1-1]

void toRubber (float hardness)

high roughness, no slip, very elastic, hardness : [5-50]

void toPlastic (float roughness)

medium slip, a bit elastic, medium hardness, roughness [0.5-2]

void toFoam (float _hardness)

large slip, not elastic, low hardness [1-30], high roughness

void toSnow (float _slip)

variable slip and roughness, not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0

void toNoContact ()

collsion callback that ignores everything Usually it is better to use the "ignorePairs" from odeHandle but if this particular one should not collide with any, this is easier.

Static Public Member Functions

static void getSurfaceParams (dSurfaceParameters &sp, const Substance &s1, const Substance &s2, double stepsize)

Combination of two surfaces.

static void printSurfaceParams (const dSurfaceParameters &surfParams)

static Substance getDefaultSubstance ()

default substance is plastic with roughness=0.8

static Substance getMetal (float roughness)

very hard and elastic with slip roughness [0.1-1]

static Substance getRubber (float hardness)

high roughness, no slip, very elastic, hardness : [5-50]

static Substance getPlastic (float roughness)

medium slip, a bit elastic, medium hardness, roughness [0.5-2]

static Substance getFoam (float _hardness)

large slip, not elastic, low hardness [1-30], high roughness

static Substance getSnow (float _slip)

variable slip and roughness [0-1], not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0

static Substance getNoContact ()

Public Attributes

float roughness

float slip

float hardness

float elasticity

CollisionCallback callback

void * userdata

Detailed Description

Physical substance definition, used for collision detection/treatment What we need is mu, slip and kp,kd parameter for the collision Definition of substance parameters:.

       Parameter    interval  collision_parameter
       roughness:  [0-]      mu   = roughness1*roughness2 
       slip:       [0-]      slip = slip1+slip2
       hardness:   [0-]      kp   = hardness1 * hardness2 / (hardness1 + hardness2) (two springs serial)
       elasticity: [0-1]     kd   = (1-elasticity1) * s2.hardness + (1-elasticity2) * s1.hardness) / 
                                    (s1.hardness + s2.hardness);

For the calculation of the spring/damping constant we use the following schema: The collision can be considered as 2 springs serially connected. The spring constant of each collision side is given by hardness (here kp). The spring constant of the entire spring is given by

$1/kp = 1/kp_1 + 1/kp_2$

. The damping (kd) is derived from the elasticity (e), but it is more difficult to compute. Consider the damping in form of energy lost. We can write the energy or work done by each spring as:

$W_i = F*s_i = F^2/p$

with

$s_i=F*kp_i$

. The energy lost though damping is

$W_1^D = W_i*(1-e_i)$

. The final damping is now:

$kd = (1-e) = W^D/W = \frac{(1-e_1)/kp_1 + (1-e_2)/kp_2}{1/kp_1 + 1/kp_2} = \frac{(1-e_1)kp_2 + (1-e_2)kp_1}{kp_1+kp_2}$

Todo: maybe add bounce

Constructor & Destructor Documentation

Substance ( )

Substance	(	float	roughness,
		float	slip,
		float	hardness,
		float	elasticity
	)

Member Function Documentation

Substance getDefaultSubstance ( ) [static]

default substance is plastic with roughness=0.8

Substance getFoam ( float _hardness ) [static]

large slip, not elastic, low hardness [1-30], high roughness

Substance getMetal ( float roughness ) [static]

very hard and elastic with slip roughness [0.1-1]

Substance getNoContact ( ) [static]

See also:: toNoContact()

Substance getPlastic ( float roughness ) [static]

medium slip, a bit elastic, medium hardness, roughness [0.5-2]

Substance getRubber ( float hardness ) [static]

high roughness, no slip, very elastic, hardness : [5-50]

Substance getSnow ( float _slip ) [static]

variable slip and roughness [0-1], not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0

void getSurfaceParams	(	dSurfaceParameters &	sp,
		const Substance &	s1,
		const Substance &	s2,
		double	stepsize
	)			`[static]`

Combination of two surfaces.

void printSurfaceParams ( const dSurfaceParameters & surfParams ) [static]

void setCollisionCallback	(	CollisionCallback	func,
		void *	userdata
	)

void toDefaultSubstance ( )

void toFoam ( float _hardness )

large slip, not elastic, low hardness [1-30], high roughness

void toMetal ( float roughness )

very hard and elastic with slip roughness [0.1-1]

void toNoContact ( )

collsion callback that ignores everything Usually it is better to use the "ignorePairs" from odeHandle but if this particular one should not collide with any, this is easier.

WARNING: this sets the collisionCallback. This will not convert to other substances without manually setting the callback to 0

void toPlastic ( float roughness )

medium slip, a bit elastic, medium hardness, roughness [0.5-2]

void toRubber ( float hardness )

high roughness, no slip, very elastic, hardness : [5-50]

void toSnow ( float _slip )

variable slip and roughness, not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0

Member Data Documentation

CollisionCallback callback

float elasticity

float hardness

float roughness

float slip

void* userdata

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

Generated on Fri Oct 30 16:29:03 2009 for Robot Simulator of the Robotics Group for Self-Organization of Control by

1.4.7


Public Member Functions
	Substance ()
	Substance (float roughness, float slip, float hardness, float elasticity)
void	setCollisionCallback (CollisionCallback func, void *userdata)
void	toDefaultSubstance ()
void	toMetal (float roughness)
	very hard and elastic with slip roughness [0.1-1]
void	toRubber (float hardness)
	high roughness, no slip, very elastic, hardness : [5-50]
void	toPlastic (float roughness)
	medium slip, a bit elastic, medium hardness, roughness [0.5-2]
void	toFoam (float _hardness)
	large slip, not elastic, low hardness [1-30], high roughness
void	toSnow (float _slip)
	variable slip and roughness, not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0
void	toNoContact ()
	collsion callback that ignores everything Usually it is better to use the "ignorePairs" from odeHandle but if this particular one should not collide with any, this is easier.
Static Public Member Functions
static void	getSurfaceParams (dSurfaceParameters &sp, const Substance &s1, const Substance &s2, double stepsize)
	Combination of two surfaces.
static void	printSurfaceParams (const dSurfaceParameters &surfParams)
static Substance	getDefaultSubstance ()
	default substance is plastic with roughness=0.8
static Substance	getMetal (float roughness)
	very hard and elastic with slip roughness [0.1-1]
static Substance	getRubber (float hardness)
	high roughness, no slip, very elastic, hardness : [5-50]
static Substance	getPlastic (float roughness)
	medium slip, a bit elastic, medium hardness, roughness [0.5-2]
static Substance	getFoam (float _hardness)
	large slip, not elastic, low hardness [1-30], high roughness
static Substance	getSnow (float _slip)
	variable slip and roughness [0-1], not elastic, high hardness for solid snow slip = 1 <--> roughness=0.0, slip = 0 <--> roughnes=1.0
static Substance	getNoContact ()
Public Attributes
float	roughness
float	slip
float	hardness
float	elasticity
CollisionCallback	callback
void *	userdata