javax.robotics.ode
Class Euler2

java.lang.Object
  javax.robotics.ode.Euler2

All Implemented Interfaces:

DerivableFunction2, Solver2

Direct Known Subclasses:

RungeKutta4th2

public class Euler2
extends java.lang.Object
implements DerivableFunction2, Solver2

This class implements forward Euler integration method for systems of two first order differential equations.

x''=f(x, x') with x(0)=x0, x'(0)= y0, is equivalent to system of two first order of differential equation:
y' = f(x, y)
x' = y
with x(0)=x0, y(0)= y0

Since:

1.0.3

Version:

09/11/2005

Author:

Carmine Lia

Field Summary

Fields inherited from interface javax.robotics.ode.Solver2

startTime

Constructor Summary

Euler2(double dt, RVector initialConditionPosition, RVector initialConditionVelocity)
Defines numerical integration for x'' = f(x, x') as system of two first order differential equation.

Euler2(double dt, RVector initialConditionPosition, RVector initialConditionVelocity, DerivableFunction2 target)
Defines numerical integration for x'' = f(x, x') as system of two first order differential equation.

Method Summary

RVector	getInitialConditionPosition() Gets the initial condition for position x(0).
RVector	getInitialConditionVelocity() Gets the initial condition for velocity x'(0).
RVector	getLastValuePosition() Gets the current value of position x computed by step function.
RVector	getLastValueVelocity() Gets the current value of velocity x'computed by step function.
double	getSampleTime() Gets the interval of integration.
double	getTime() Gets current time of integration.
void	resetTime() Sets the current time to zero.
void	setInitialConditionPosition(RVector initialCondition) Sets the initial condition for position x(0) = x0.
void	setInitialConditionVelocity(RVector initialCondition) Sets the initial condition for velocity x'(0) = y0.
void	setSampleTime(double dt) Sets the interval of integration.
void	setTargetFunction(DerivableFunction2 target) Sets the target function to be integrated
void	step(RVector position, RVector velocity) Computes step integration from time t to t+dt of x'' = f(x, x').
RVector	xDot2(RVector x, RVector y) Second order function x'' = f(x, x').

Methods inherited from class java.lang.Object

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

Constructor Detail

Euler2

public Euler2(double dt,
              RVector initialConditionPosition,
              RVector initialConditionVelocity)

Defines numerical integration for x'' = f(x, x') as system of two first order differential equation.

Parameters:

dt - time interval of integration [sec]

initialConditionPosition - position at time zero x(0).

initialConditionVelocity - velocity at time zero x'(0).

Euler2

public Euler2(double dt,
              RVector initialConditionPosition,
              RVector initialConditionVelocity,
              DerivableFunction2 target)

Defines numerical integration for x'' = f(x, x') as system of two first order differential equation.

Parameters:

dt - time interval of integration [sec]

initialConditionPosition - position at time zero x(0).

initialConditionVelocity - velocity at time zero x'(0).

target - differential equation to be integrated

Method Detail

setSampleTime

public final void setSampleTime(double dt)

Description copied from interface: Solver2

Sets the interval of integration.

Specified by:

setSampleTime in interface Solver2

Parameters:

dt - interval [sec]

getSampleTime

public final double getSampleTime()

Description copied from interface: Solver2

Gets the interval of integration.

Specified by:

getSampleTime in interface Solver2

Returns:

the dt interval [sec]

setInitialConditionPosition

public final void setInitialConditionPosition(RVector initialCondition)

Description copied from interface: Solver2

Sets the initial condition for position x(0) = x₀.

Specified by:

setInitialConditionPosition in interface Solver2

setInitialConditionVelocity

public final void setInitialConditionVelocity(RVector initialCondition)

Description copied from interface: Solver2

Sets the initial condition for velocity x'(0) = y₀.

Specified by:

setInitialConditionVelocity in interface Solver2

getInitialConditionPosition

public final RVector getInitialConditionPosition()

Description copied from interface: Solver2

Gets the initial condition for position x(0).

Specified by:

getInitialConditionPosition in interface Solver2

Returns:

the initialCondition

getInitialConditionVelocity

public final RVector getInitialConditionVelocity()

Description copied from interface: Solver2

Gets the initial condition for velocity x'(0).

Specified by:

getInitialConditionVelocity in interface Solver2

Returns:

the initialCondition

getLastValuePosition

public final RVector getLastValuePosition()

Description copied from interface: Solver2

Gets the current value of position x computed by step function.

Specified by:

getLastValuePosition in interface Solver2

Returns:

the current position.

getLastValueVelocity

public final RVector getLastValueVelocity()

Description copied from interface: Solver2

Gets the current value of velocity x'computed by step function.

Specified by:

getLastValueVelocity in interface Solver2

Returns:

the current velocity.

getTime

public final double getTime()

Description copied from interface: Solver2

Gets current time of integration.

Specified by:

getTime in interface Solver2

Returns:

the current time [sec]

resetTime

public final void resetTime()

Description copied from interface: Solver2

Sets the current time to zero.

Specified by:

resetTime in interface Solver2

setTargetFunction

public void setTargetFunction(DerivableFunction2 target)

Description copied from interface: Solver2

Sets the target function to be integrated

Specified by:

setTargetFunction in interface Solver2

Parameters:

target - the function.

step

public void step(RVector position,
                 RVector velocity)

Description copied from interface: Solver2

Computes step integration from time t to t+dt of x'' = f(x, x'). The params last value position and velocity are modified.

Specified by:

step in interface Solver2

Parameters:

position - x argument of f(x, x')

velocity - x' argument of f(x, x')

xDot2

public RVector xDot2(RVector x,
                     RVector y)

Description copied from interface: DerivableFunction2

Second order function x'' = f(x, x').

Specified by:

xDot2 in interface DerivableFunction2

Parameters:

x - first indipendent variable (position)

y - second indipendent variable (velocity).

Returns:

x'' (acceleration)