OpenSim::CustomForce Class Reference

This is an abstract subclass of Force which allows you to define new Force types by overriding methods, rather than having to create a new SimTK::Force subclass. More...

#include <CustomForce.h>

Inheritance diagram for OpenSim::CustomForce:

List of all members.

Public Member Functions
	CustomForce ()
	CustomForce (const CustomForce &aForce)
	Copy constructor.
void	createSystem (SimTK::MultibodySystem &system) const
	Create a SimTK::Force which implements this CustomForce.
Protected Member Functions
virtual void	computeForce (const SimTK::State &state) const =0
	Subclasses must implement this method to compute the forces that should be applied to bodies and generalized speeds.
virtual double	computePotentialEnergy (const SimTK::State &state) const
	Subclasses may optionally override this method to compute a contribution to the potential energy of the system.
void	applyForce (const OpenSim::Body &aBody, const SimTK::Vec3 &aForce) const
	Apply a force to a particular body.
void	applyForceToPoint (const OpenSim::Body &aBody, const SimTK::Vec3 &aPoint, const SimTK::Vec3 &aForce) const
	Apply a force to a particular body.
void	applyTorque (const OpenSim::Body &aBody, const SimTK::Vec3 &aTorque) const
	Apply a torque to a particular body.
void	applyGeneralizedForce (const Coordinate &aCoord, double aForce) const
	Apply a force to a generalized coordinate.
void	computeForce (const SimbodyEngine &engine, const SimTK::State &state, SimTK::Vector_< SimTK::SpatialVec > &bodyForces, SimTK::Vector &mobilityForces) const
	This is invoked by ForceAdapter to perform the force computation.
Friends
class	ForceAdapter

---

Detailed Description

This is an abstract subclass of Force which allows you to define new Force types by overriding methods, rather than having to create a new SimTK::Force subclass.

---

Constructor & Destructor Documentation

CustomForce::CustomForce

(

)

CustomForce::CustomForce

(

const CustomForce &

aForce

)

Copy constructor.

Parameters:

aActuator

Actuator to copy.

---

Member Function Documentation

void OpenSim::CustomForce::applyForce	(	const OpenSim::Body &	aBody,
		const SimTK::Vec3 &	aForce
	)			const [protected]

Apply a force to a particular body.

This method applies only a force, not a torque, which is equivalent to applying the force at the body's center of mass.

This method may only be called from inside computeForce(). Invoking it at any other time will produce an exception.

Parameters:

	aBody	the body to apply the force to
	aForce	the force to apply, specified in the inertial frame

void OpenSim::CustomForce::applyForceToPoint	(	const OpenSim::Body &	aBody,
		const SimTK::Vec3 &	aPoint,
		const SimTK::Vec3 &	aForce
	)			const [protected]

Apply a force to a particular body.

Based on what point the force is applied at, this method automatically determines the torque produced by the force and applies that as well.

This method may only be called from inside computeForce(). Invoking it at any other time will produce an exception.

Parameters:

	aBody	the body to apply the force to
	aPoint	the point at which to apply the force, specifieid in the inertial frame
	aForce	the force to apply, specified in the body's frame

void CustomForce::applyGeneralizedForce	(	const Coordinate &	aCoord,
		double	aForce
	)			const [protected]

Apply a force to a generalized coordinate.

This method may only be called from inside computeForce(). Invoking it at any other time will produce an exception.

Parameters:

	aU	the generalized speed to apply the force to
	aForce	the force to apply

void OpenSim::CustomForce::applyTorque	(	const OpenSim::Body &	aBody,
		const SimTK::Vec3 &	aTorque
	)			const [protected]

Apply a torque to a particular body.

This method may only be called from inside computeForce(). Invoking it at any other time will produce an exception.

Parameters:

	aBody	the body to apply the force to
	aTorque	the torque to apply, specified in the inertial frame

void CustomForce::computeForce	(	const SimbodyEngine &	engine,
		const SimTK::State &	state,
		SimTK::Vector_< SimTK::SpatialVec > &	bodyForces,
		SimTK::Vector &	mobilityForces
	)			const [protected]

This is invoked by ForceAdapter to perform the force computation.

virtual void OpenSim::CustomForce::computeForce

(

const SimTK::State &

state

)

const [protected, pure virtual]

Subclasses must implement this method to compute the forces that should be applied to bodies and generalized speeds.

Implemented in OpenSim::SpringGeneralizedForce, OpenSim::Ligament, OpenSim::LinearSpring, OpenSim::PrescribedForce, and OpenSim::TorsionalSpring.

double CustomForce::computePotentialEnergy

(

const SimTK::State &

state

)

const [protected, virtual]

Subclasses may optionally override this method to compute a contribution to the potential energy of the system.

The default implementation returns 0, which is appropriate for forces that do not contribute to potential energy.

void CustomForce::createSystem

(

SimTK::MultibodySystem &

system

)

const [virtual]

Create a SimTK::Force which implements this CustomForce.

Reimplemented from OpenSim::ModelComponent.

---

Friends And Related Function Documentation

friend class ForceAdapter [friend]

---

The documentation for this class was generated from the following files:

• OpenSim/Simulation/Model/CustomForce.h
• OpenSim/Simulation/Model/CustomForce.cpp