XWalkParameters Class Reference

Parameters used by XWalkMC to control gait. More...

#include <XWalkParameters.h>

Inheritance diagram for XWalkParameters:

Detailed Description

Parameters used by XWalkMC to control gait.

One instance of this class is a public superclass which clients can modify directly, and a second instance is stored internally by XWalkMC which allows it to smoothly transition parameter values when they are updated. (See XWalkMC::ParameterTransition)

Definition at line 11 of file XWalkParameters.h.

List of all members.

Classes
class	LegParameters
	Specifies parameters for each leg. More...
class	SinusoidalParameters
	Specifies parameters for shifting the body position while in motion. More...
Public Member Functions
	XWalkParameters ()
	constructor, sets default values
	XWalkParameters (const XWalkParameters &p)
	copy constructor, forwards to operator=
void	packGroundGravity (const fmat::SubVector< 3 > &ground, const fmat::SubVector< 3 > gravity) const
	converts the gravity and ground configuration parameters to fmat data structures for further calculations
float	getMaxXVel () const
	returns fastest possible foward velocity given the current parameters (mm/s)
float	getMaxYVel () const
	returns fastest possible sideways velocity given the current parameters (mm/s)
float	getMaxAVel () const
	returns fastest possible rotational velocity given the current parameters (rad/s)
fmat::Column< 2 >	computeNeutralPos (unsigned int leg) const
	returns center point of stride
Static Public Member Functions
static void	projectToGround (const fmat::Column< 3 > &ground, float height, const fmat::Column< 3 > &gravity, fmat::Column< 3 > &tgt)
	projects point to ground plane along gravity vector
Public Attributes
plist::ArrayOf < plist::Primitive< float > >	groundPlane
	equation of the ground plane relative to the base frame (in millimeters)
plist::ArrayOf < plist::Primitive< float > >	gravityVector
	Vector indicating direction of gravity's pull, relative to the ground plane normal vector; this influences the projection of the foot positions onto the ground plane, magnitude is arbitrary.
plist::Primitive< float >	offsetX
	Bias the position of the body relative to the ground (in millimeters), so increasing this parameter moves the robot forward, parallel to the ground.
plist::Primitive< float >	offsetY
	Bias the position of the body relative to the ground (in millimeters), so increasing this parameter moves the robot left, parallel to the ground.
plist::Primitive< float >	offsetA
	Bias the orientation of the body relative to the ground (in radians), so increasing this parameter turns the robot counter-clockwise.
plist::Primitive< bool >	resetOnStop
	Causes the feet to redistribute to their central positions when motion stops.
plist::Primitive< float >	frictionCoef
	Coefficient of friction with the ground (aka µ), limits the amount of non-normal force which can be applied.
plist::Primitive< float >	strideLenX
	The size of step to take with each leg (all legs have the same period and travel same speed, so must have the same length of stride).
plist::Primitive< float >	strideLenY
	The size of step to take with each leg (all legs have the same period and travel same speed, so must have the same length of stride).
plist::Primitive< bool >	adaptiveLegOrder
	Whether to re-order the leg flights based on direction of motion.
plist::Primitive< bool >	rotateBodyMotion
	Whether to rotate the sway and surge motions to match direction of motion.
plist::Primitive< unsigned int >	transitionDuration
	How much time to use getting into initial position, or when parameters change (milliseconds).
SinusoidalParameters	bounce
	moves the body up and down
SinusoidalParameters	sway
	moves the body left and right
SinusoidalParameters	surge
	moves the body forward and back
plist::ArrayOf< LegParameters >	legParams
plist::DictionaryOf < SinusoidalParameters >	nonLegJoints
Protected Member Functions
void	init ()
float	nominalPeriod () const
float	minPeriod () const
Static Protected Attributes
static const float	EPSILON = 1e-5f
	limit of resolution for various computations

Constructor & Destructor Documentation

XWalkParameters::XWalkParameters ( )

constructor, sets default values

Definition at line 17 of file XWalkParameters.h.

XWalkParameters::XWalkParameters ( const XWalkParameters & p )

copy constructor, forwards to operator=

Definition at line 26 of file XWalkParameters.h.

Member Function Documentation

fmat::Column< 2 > XWalkParameters::computeNeutralPos ( unsigned int leg ) const

returns center point of stride

Definition at line 57 of file XWalkParameters.cc.

Referenced by getMaxAVel().

float XWalkParameters::getMaxAVel ( ) const

returns fastest possible rotational velocity given the current parameters (rad/s)

Definition at line 17 of file XWalkParameters.cc.

Referenced by GaitedFootstepMC::setGait(), and XWalkMC::setTargetDisplacement().

float XWalkParameters::getMaxXVel ( ) const

returns fastest possible foward velocity given the current parameters (mm/s)

Definition at line 11 of file XWalkParameters.cc.

Referenced by GaitedFootstepMC::setGait(), and XWalkMC::setTargetDisplacement().

float XWalkParameters::getMaxYVel ( ) const

returns fastest possible sideways velocity given the current parameters (mm/s)

Definition at line 14 of file XWalkParameters.cc.

Referenced by GaitedFootstepMC::setGait(), and XWalkMC::setTargetDisplacement().

void XWalkParameters::init ( ) [protected]

Definition at line 168 of file XWalkParameters.h.

Referenced by XWalkParameters().

float XWalkParameters::minPeriod ( ) const [protected]

Definition at line 44 of file XWalkParameters.cc.

Referenced by getMaxAVel(), getMaxXVel(), and getMaxYVel().

float XWalkParameters::nominalPeriod ( ) const [protected]

Definition at line 31 of file XWalkParameters.cc.

Referenced by XWalkMC::resetPeriod().

void XWalkParameters::packGroundGravity	(	const fmat::SubVector< 3 > &	ground,
		const fmat::SubVector< 3 >	gravity
	)			const

converts the gravity and ground configuration parameters to fmat data structures for further calculations

gravity will be normalized, ground will just be the first three terms of groundPlane

Definition at line 87 of file XWalkParameters.cc.

Referenced by GaitedFootsteps::setGait(), GaitedFootstepMC::setGait(), and XWalkMC::updateOutputs().

void XWalkParameters::projectToGround	(	const fmat::Column< 3 > &	ground,
		float	height,
		const fmat::Column< 3 > &	gravity,
		fmat::Column< 3 > &	tgt
	)			`[static]`

projects point to ground plane along gravity vector

Definition at line 71 of file XWalkParameters.cc.

Referenced by GaitedFootsteps::addCandidate(), GaitedFootsteps::addRotation(), GaitedFootsteps::expand(), GaitedFootstepMC::updateOutputs(), XWalkMC::updateOutputsInitial(), and XWalkMC::updateOutputsWalking().

Member Data Documentation

plist::Primitive<bool> XWalkParameters::adaptiveLegOrder

Whether to re-order the leg flights based on direction of motion.

Definition at line 93 of file XWalkParameters.h.

Referenced by XWalkMC::computeLegPhase(), init(), and XWalkMC::setTargetVelocity().

SinusoidalParameters XWalkParameters::bounce

moves the body up and down

Definition at line 128 of file XWalkParameters.h.

Referenced by init(), and XWalkMC::updateOutputsWalking().

const float XWalkParameters::EPSILON = 1e-5f [static, protected]

limit of resolution for various computations

Definition at line 13 of file XWalkParameters.h.

Referenced by XWalkMC::computeCurrentBodyOffset(), XWalkMC::computeCurrentPosition(), XWalkMC::computePressure(), XWalkMC::isDirty(), projectToGround(), XWalkMC::resetPeriod(), XWalkMC::sendLoadPredictions(), XWalkMC::setTargetVelocity(), and XWalkMC::updateOutputsWalking().

plist::Primitive<float> XWalkParameters::frictionCoef

Coefficient of friction with the ground (aka µ), limits the amount of non-normal force which can be applied.

Definition at line 81 of file XWalkParameters.h.

Referenced by init().

plist::ArrayOf<plist::Primitive<float> > XWalkParameters::gravityVector

Vector indicating direction of gravity's pull, relative to the ground plane normal vector; this influences the projection of the foot positions onto the ground plane, magnitude is arbitrary.

This vector is added to the normal vector to the ground plane from the body frame origin. Thus, leaving this vector at (0,0,0) means that the gravity vector will always point straight into the ground, and adjusting the ground plane will change the attitude of the body without affecting foot positions. However, adjusting this instead of the groundPlane adjusts feet positions while keeping body parallel to the ground. Adjusting both is necessarily if you want to keep the body Z-axis aligned with gravity while walking uphill.

Definition at line 63 of file XWalkParameters.h.

Referenced by init(), and packGroundGravity().

plist::ArrayOf<plist::Primitive<float> > XWalkParameters::groundPlane

equation of the ground plane relative to the base frame (in millimeters)

The equation is of the form $p_1x + p_2y + p_3z = p_4$ , relative to the base frame, the first three parameters should be normalized. See also gravityVector.