XWalkMC Class Reference

Extreme walk engine handles legged locomotion on hexapods and beyond. More...

#include <XWalkMC.h>

Inheritance diagram for XWalkMC:

[legend]

Detailed Description

Extreme walk engine handles legged locomotion on hexapods and beyond.

Definition at line 17 of file XWalkMC.h.

List of all members.

Classes
struct	LegState
	contains cached information about each leg's stride More...
class	ParameterTransition
Public Member Functions
	XWalkMC ()
	constructor
const fmat::Column< 2 > &	getTargetVelocity () const
	Returns the current x and y velocities in mm/sec.
float	getTargetAngVelocity () const
	Returns the current angular velocity in radians/sec.
virtual void	getTargetVelocity (float &xvel, float &yvel, float &avel)
	Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second).
virtual void	setTargetVelocity (float xvel, float yvel, float avel)
	Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second); does not stop automatically.
virtual void	setTargetVelocity (float xvel, float yvel, float avel, float time)
	Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second), and amount of time (seconds) before stopping.
virtual void	setTargetDisplacement (float xdisp, float ydisp, float adisp, float time=0)
	Specify the desired body displacement in x and y (millimeters) and angle (radians), optionally specify time (seconds).
virtual int	updateOutputs ()
	is called once per update cycle, can do any processing you need to change your priorities or set output commands on the MotionManager
virtual int	isDirty ()
	not used by MotionManager at the moment, but could be used to reduce recomputation, and you may find it useful
virtual int	isAlive ()
	used to prune "dead" motions from the MotionManager
virtual void	start ()
	called after this is added to MotionManager; don't override this, use doStart instead
virtual void	stop ()
	called after this is removed from MotionManager; don't override this, use doStop instead
virtual void	zeroVelocities ()
	Posts a LocomotionEvent and sets velocities to zero. Also forces an output frame setting wheel velocities to zero; needed because if we remove a motion command there may be nothing left to zero the velocities.
Protected Member Functions
void	updateNeutralPos (unsigned int curTime)
	recomputes each leg's LegState::neutralPos based on current values in p
bool	resetPeriod (float time, float speed)
void	resetLegState (unsigned int leg, float phase, const fmat::Column< 3 > &curPos, bool inAir, float speed)
	recomputes LegState::downPos and LegState::liftPos based on specified state variables, such that the direction of stride rotates about the current position
void	updateOutputsInitial (unsigned int curTime, const fmat::Column< 3 > &ground, const fmat::Column< 3 > &gravity, IKSolver::Point tgts[])
void	updateOutputsWalking (float dt, const fmat::Column< 3 > &ground, const fmat::Column< 3 > &gravity, float speed, IKSolver::Point tgts[])
void	sendLoadPredictions (IKSolver::Point tgts[])
void	computePhase (float time)
	updates globPhase based on specified stride time (relative to startTime)
void	computeLegPhase (unsigned int leg, bool &inAir, float &phase)
	computes current leg state based on globPhase
void	computeCurrentPosition (unsigned int leg, bool inAir, float speed, float phase, fmat::Column< 3 > &tgt)
	computes the leg position (in xy plane only) based on leg state
void	computeCurrentBodyOffset (float *legPhases, float speed, float &offx, float &offy, float &offa)
	computes body position based on settings in p, which should then be added to leg positions before projecting onto ground plane
void	solveIK (unsigned int leg, const IKSolver::Point &tgt)
	solves inverse kinematics and send affected output values to motion manager
void	computePressure (float mass, float massx, float massy, const std::vector< fmat::Column< 2 > > &contacts, std::vector< float > &pressures)
void	spiderSettings (plist::DictionaryBase &src, plist::DictionaryBase &dst)
	recursively processes contents of src, creating a ParameterTransition for each entry to smoothly update corresponding entries in dst
void	spiderSettings (plist::ArrayBase &src, plist::ArrayBase &dst)
	recursively processes contents of src, creating a ParameterTransition for each entry to smoothly update corresponding entries in dst
Protected Attributes
fmat::Column< 2 >	targetVel
	the requested xy velocity of the body (ignoring parameterized body motion, like sway or surge), millimeters per second
float	targetAngVel
	the requested angular velocity of the body, radians per second
fmat::Column< 2 >	targetDisp
	the requesed xy displacement of the body, in millimeters
float	targetAngDisp
	the requested angular displacement of the body in radians
bool	velocityMode
	True if we just want to maintain a velocity; false if we're trying to achieve a displacement.
unsigned int	displacementTime
	time in msecs since setTargetDisplacement called
bool	plantingLegs
	True if we've finished a displacement and are waiting for all legs to come to ground before posting a status event.
bool	initialPlacement
	set to true when legs are in an unknown configuration (e.g. following start())
XWalkParameters	p
	current parameter values, subject to smoothed transition from those as members of the superclass (see ParameterTransition)
std::set< ParameterTransition * >	transitions
	full collection of parameter listeners
std::set< ParameterTransition * >	active
	collection of those listeners which are actively transitioning their corresponding parameters in p
float	startTime
	must be float (not unsigned int) because value can go negative: phase offset of "walk time" from system get_time() (milliseconds)
float	period
	the time between leg lifts (milliseconds), calculated value to yield target speed (targetVel)
float	globPhase
	the current phase within the walk, in turn controls phase of individual legs via updateLegPhase()
fmat::Column< 2 >	rotationCenter
	if the target angular velocity (targetAngVel) is producing a reasonable curvature vs. targetVel, this is the point about which the body is arcing
DriverMessaging::FixedPoints	contactMsg
	list of current contact points, for better Mirage simulation
LegState	legStates [NumLegs]
	storage of cached stride information for each leg
Static Protected Attributes
static KinematicJoint *	kine = NULL
static KinematicJoint *	childMap [NumReferenceFrames]

Constructor & Destructor Documentation

XWalkMC::XWalkMC ( )

constructor

Definition at line 20 of file XWalkMC.h.

Member Function Documentation

void XWalkMC::computeCurrentBodyOffset	(	float *	legPhases,
		float	speed,
		float &	offx,
		float &	offy,
		float &	offa
	)			`[protected]`

computes body position based on settings in p, which should then be added to leg positions before projecting onto ground plane

Definition at line 903 of file XWalkMC.cc.

Referenced by setTargetVelocity(), updateOutputsInitial(), and updateOutputsWalking().

void XWalkMC::computeCurrentPosition	(	unsigned int	leg,
		bool	inAir,
		float	speed,
		float	phase,
		fmat::Column< 3 > &	tgt
	)			`[protected]`

computes the leg position (in xy plane only) based on leg state

Definition at line 882 of file XWalkMC.cc.

Referenced by resetLegState(), setTargetVelocity(), and updateOutputsWalking().

void XWalkMC::computeLegPhase	(	unsigned int	leg,
		bool &	inAir,
		float &	phase
	)			`[protected]`

computes current leg state based on globPhase

Definition at line 867 of file XWalkMC.cc.

Referenced by setTargetVelocity(), updateOutputsInitial(), and updateOutputsWalking().

void XWalkMC::computePhase ( float time ) [protected]

updates globPhase based on specified stride time (relative to startTime)

Definition at line 860 of file XWalkMC.cc.

Referenced by resetPeriod(), setTargetVelocity(), start(), updateOutputsInitial(), and updateOutputsWalking().

void XWalkMC::computePressure	(	float	mass,
		float	massx,
		float	massy,
		const std::vector< fmat::Column< 2 > > &	contacts,
		std::vector< float > &	pressures
	)			`[protected]`

Parameters:

	mass	being supported in kilograms
	massx	center of mass along x axis, in millimeters
	massy	center of mass along y axis, in millimeters
	contacts	position of each support contact, in millimeters
`[out]`	pressures	will be resized and overwritten with pressure at each corresponding point in contacts, in newtons

Note the z position is irrelevant, all points should be projected to the same plane, normal to gravity vector.
Thanks Jacqueline K. Libby for helping figure out the free-body diagram/computation upon which this function is based.

Definition at line 995 of file XWalkMC.cc.

Referenced by sendLoadPredictions().

float XWalkMC::getTargetAngVelocity ( ) const

Returns the current angular velocity in radians/sec.

Definition at line 40 of file XWalkMC.h.

virtual void XWalkMC::getTargetVelocity	(	float &	xvel,
		float &	yvel,
		float &	avel
	)			`[virtual]`

Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second).

Definition at line 43 of file XWalkMC.h.

const fmat::Column<2>& XWalkMC::getTargetVelocity ( ) const

Returns the current x and y velocities in mm/sec.

Definition at line 37 of file XWalkMC.h.

virtual int XWalkMC::isAlive ( ) [virtual]

used to prune "dead" motions from the MotionManager

note that a motion could be "paused" or inactive and therefore not dirty, but still alive, biding its time to "strike" ;)

Returns:: zero if the motion is still processing, non-zero otherwise

Implements MotionCommand.

Definition at line 68 of file XWalkMC.h.

virtual int XWalkMC::isDirty ( ) [virtual]

not used by MotionManager at the moment, but could be used to reduce recomputation, and you may find it useful

Returns:: zero if none of the commands have changed since last getJointCmd(), else non-zero

Implements MotionCommand.

Definition at line 61 of file XWalkMC.h.

Referenced by computePhase(), and updateOutputs().

void XWalkMC::resetLegState	(	unsigned int	leg,
		float	phase,
		const fmat::Column< 3 > &	curPos,
		bool	inAir,
		float	speed
	)			`[protected]`

recomputes LegState::downPos and LegState::liftPos based on specified state variables, such that the direction of stride rotates about the current position

Definition at line 458 of file XWalkMC.cc.

Referenced by start(), and updateOutputsInitial().

bool XWalkMC::resetPeriod	(	float	time,
		float	speed
	)			`[protected]`

Definition at line 386 of file XWalkMC.cc.

Referenced by setTargetVelocity().

void XWalkMC::sendLoadPredictions ( IKSolver::Point tgts[] ) [protected]

Definition at line 782 of file XWalkMC.cc.

Referenced by updateOutputs().

void XWalkMC::setTargetDisplacement	(	float	xdisp,
		float	ydisp,
		float	adisp,
		float	time = `0`
	)			`[virtual]`

Specify the desired body displacement in x and y (millimeters) and angle (radians), optionally specify time (seconds).

Corresponding velocity will be limited to max velocity, so setting time=0 implies max speed

Definition at line 199 of file XWalkMC.cc.

void XWalkMC::setTargetVelocity	(	float	xvel,
		float	yvel,
		float	avel,
		float	time
	)			`[virtual]`

Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second), and amount of time (seconds) before stopping.

Definition at line 186 of file XWalkMC.cc.

void XWalkMC::setTargetVelocity	(	float	xvel,
		float	yvel,
		float	avel
	)			`[virtual]`

Specify the desired body velocity in x and y (millimeters per second) and angular velocity (radians per second); does not stop automatically.

Definition at line 17 of file XWalkMC.cc.

Referenced by setTargetDisplacement(), setTargetVelocity(), updateOutputs(), XWalkMC(), and zeroVelocities().

void XWalkMC::solveIK	(	unsigned int	leg,
		const IKSolver::Point &	tgt
	)			`[protected]`

solves inverse kinematics and send affected output values to motion manager

Definition at line 919 of file XWalkMC.cc.

Referenced by updateOutputsInitial(), and updateOutputsWalking().

void XWalkMC::spiderSettings	(	plist::ArrayBase &	src,
		plist::ArrayBase &	dst
	)			`[protected]`

recursively processes contents of src, creating a ParameterTransition for each entry to smoothly update corresponding entries in dst

Definition at line 1079 of file XWalkMC.cc.

void XWalkMC::spiderSettings	(	plist::DictionaryBase &	src,
		plist::DictionaryBase &	dst
	)			`[protected]`

recursively processes contents of src, creating a ParameterTransition for each entry to smoothly update corresponding entries in dst

Definition at line 1065 of file XWalkMC.cc.

Referenced by spiderSettings(), and XWalkMC().

void XWalkMC::start ( ) [virtual]

called after this is added to MotionManager; don't override this, use doStart instead

Reimplemented from MotionCommand.

Definition at line 280 of file XWalkMC.cc.

void XWalkMC::stop ( ) [virtual]

called after this is removed from MotionManager; don't override this, use doStop instead

Reimplemented from MotionCommand.

Definition at line 303 of file XWalkMC.cc.

void XWalkMC::updateNeutralPos ( unsigned int curTime ) [protected]

recomputes each leg's LegState::neutralPos based on current values in p

Definition at line 367 of file XWalkMC.cc.

Referenced by updateOutputs(), and XWalkMC().

int XWalkMC::updateOutputs ( ) [virtual]

is called once per update cycle, can do any processing you need to change your priorities or set output commands on the MotionManager

Returns:: zero if no changes were made, non-zero otherwise

See also:: RobotInfo::NumFrames; RobotInfo::FrameTime

Implements MotionCommand.

Reimplemented in WaypointWalkMC.

Definition at line 218 of file XWalkMC.cc.

void XWalkMC::updateOutputsInitial	(	unsigned int	curTime,
		const fmat::Column< 3 > &	ground,
		const fmat::Column< 3 > &	gravity,
		IKSolver::Point	tgts[]
	)			`[protected]`

Definition at line 489 of file XWalkMC.cc.

Referenced by updateOutputs().

void XWalkMC::updateOutputsWalking	(	float	dt,
		const fmat::Column< 3 > &	ground,
		const fmat::Column< 3 > &	gravity,
		float	speed,
		IKSolver::Point	tgts[]
	)			`[protected]`

Definition at line 631 of file XWalkMC.cc.

Referenced by updateOutputs().

void XWalkMC::zeroVelocities ( ) [virtual]

Posts a LocomotionEvent and sets velocities to zero. Also forces an output frame setting wheel velocities to zero; needed because if we remove a motion command there may be nothing left to zero the velocities.

Definition at line 325 of file XWalkMC.cc.