Module com.marginallyclever.robotoverlord

Package com.marginallyclever.convenience.approximatejacobian

Class ApproximateJacobian

java.lang.Object

com.marginallyclever.convenience.approximatejacobian.ApproximateJacobian

Direct Known Subclasses:

ApproximateJacobianFiniteDifferences, ApproximateJacobianScrewTheory

public abstract class ApproximateJacobian
extends Object

ApproximateJacobian is used to calculate the Jacobian matrix for a robot arm. Each implementation can derive this class and fill in the jacobian matrix.

This class provides several functionalities:

• It can get the inverse Jacobian matrix.
• It can get the joint velocity from the Cartesian velocity.
• It can get the Cartesian velocity from the joint velocity.
• It can get the Jacobian matrix.
• It can get the time derivative of the Jacobian matrix.
• It can get the Coriolis term.

Method Summary

Modifier and Type	Method	Description
double[]	getCartesianFromJoint(double[] joint)	Use the jacobian to convert joint velocity to cartesian velocity.
double[]	getCoriolisTerm(double[] jointVelocities)	Calculate the coriolis term.
double[][]	getJacobian()
double[]	getJointFromCartesian(double[] cartesianVelocity)	Use the Jacobian to get the joint velocity from the cartesian velocity.
double[][]	getTimeDerivative(double[] jointVelocities)	The time derivative is calculated by multiplying the jacobian by the joint velocities.
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Details

getJointFromCartesian

public double[] getJointFromCartesian(double[] cartesianVelocity)
                               throws Exception

Use the Jacobian to get the joint velocity from the cartesian velocity.

Parameters:

cartesianVelocity - 6 doubles - the XYZ translation and UVW rotation forces on the end effector. The rotation component is in radians.

Returns:

joint velocity in degrees. Will be filled with the new velocity.

Throws:

Exception - if joint velocities have NaN values

getCartesianFromJoint

public double[] getCartesianFromJoint(double[] joint)

Use the jacobian to convert joint velocity to cartesian velocity.

Parameters:

joint - joint velocity in degrees.

Returns:

6 doubles containing the XYZ translation and UVW rotation forces on the end effector. The rotation component is in radians.

getJacobian

public double[][] getJacobian()

toString

public String toString()

Overrides:

toString in class Object

getTimeDerivative

public double[][] getTimeDerivative(double[] jointVelocities)

The time derivative is calculated by multiplying the jacobian by the joint velocities. You can do this by taking the derivative of each element of the Jacobian matrix individually.

Parameters:

jointVelocities - joint velocities in radians. In classical notation this would be qDot.

Returns:

the time derivative of the Jacobian matrix.

getCoriolisTerm

public double[] getCoriolisTerm(double[] jointVelocities)

Calculate the coriolis term.

Parameters:

jointVelocities - joint velocities in radians. In classical notation this would be qDot.

Returns:

the coriolis term.