shady.common.multi.chain
Class DLSIK

java.lang.Object
  shady.common.multi.chain.ChainIK
      shady.common.multi.chain.DLSIK

public class DLSIK
extends ChainIK

Damped Least Squares Inverse Kinematics for a MultiShady chain.

Following Introduction to Inverse Kinematics with Jacobian Transpose, Pseudoinverse and Damped Least Squares Methods by Samuel R. Buss, unpublished, 2004, this method computes ChainIK.dofDelta by transforming the target error vector e = (ChainIK.dx, ChainIK.dy, ChainIK.dt) through the matrix

 J'(JJ'+lambda^2I)^(-1)

 

, where lambda is a non-zero damping constant.

Copyright (C) 2006 Marsette A. Vona, III

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

Author:

Marsette (Marty) A. Vona, III

Field Summary

private static java.lang.String	cvsid CVS id.
static boolean	DEBUG Whether to debug.
static double	DEFAULT_LAMBDA Default damping constant.
protected Jama.Matrix	e The error vector.
protected double[][]	E The error vector matrix.
protected double[][]	J Local reference to the Jacobian array.
protected double[][]	JJTL2I Reference to JJTPlusLambda2I's array.
protected Jama.Matrix	JJTPlusLambda2I [3 x 3] JJ'+lambda^2I.
static double	lambda Damping constant.

Fields inherited from class shady.common.multi.chain.ChainIK

blockEndToChainEnd, blockStartToEnd, blockStartToEndWithDelta, chainEnd, chainEndToWorld, chainEndToWorldWithDelta, chainStart, DEBUG_ITERATION, DEFAULT_DOF_DELTA_CLAMP, DEFAULT_TARGET_CLAMP, dofDelta, dofDeltaClamp, dt, dx, dy, jacobian, JACOBIAN_DELTA, n, sentinel, targetClamp, worldToBlockStart, worldToChainEnd, worldToChainEndWithDelta

Constructor Summary

DLSIK(Block chainEnd)
Construct a new DLSIK for a chain.

Method Summary

protected void

computeDOFDelta(int iteration) Subclasses must implement this to compute ChainIK.dofDelta vector from current ChainIK.jacobian and vector to target (ChainIK.dx, ChainIK.dy, ChainIK.dt).

Methods inherited from class shady.common.multi.chain.ChainIK

clampDOFDelta, clampDOFDeltaMagnitude, clampTarget, clampTargetMagnitude, closeEnough, gotoTarget, updateJacobian

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cvsid

private static final java.lang.String cvsid

CVS id.

See Also:

Constant Field Values

DEBUG

public static final boolean DEBUG

Whether to debug.

See Also:

Constant Field Values

DEFAULT_LAMBDA

public static final double DEFAULT_LAMBDA

Default damping constant.

See Also:

Constant Field Values

J

protected double[][] J

Local reference to the Jacobian array.

JJTPlusLambda2I

protected Jama.Matrix JJTPlusLambda2I

[3 x 3] JJ'+lambda^2I.

JJTL2I

protected double[][] JJTL2I

Reference to JJTPlusLambda2I's array.

e

protected Jama.Matrix e

The error vector.

E

protected double[][] E

The error vector matrix.

lambda

public static double lambda

Damping constant.

Constructor Detail

DLSIK

public DLSIK(Block chainEnd)

Construct a new DLSIK for a chain.

Parameters:

chainEnd - the end of the chain to control, not null. Note that the actual chain may be longer, but IK control will only be applied to (non-locked) blocks at or before chainEnd.

Method Detail

computeDOFDelta

protected void computeDOFDelta(int iteration)

Subclasses must implement this to compute ChainIK.dofDelta vector from current ChainIK.jacobian and vector to target (ChainIK.dx, ChainIK.dy, ChainIK.dt).

This is the main IK step.

Following [Buss] this impl computes

• f that solves JJTPlusLambda2If = e
• ChainIK.dofDelta = J'f

Specified by:

computeDOFDelta in class ChainIK

Parameters:

iteration - iteration number