OpenSim::ActuatorForceTargetFast Class Reference

A Computed Muscle Control (CMC) optimization target for controlling dynamic systems whose actuators may be themselves governed by differential equations, meaning there may be non-linear behavior and delays in force production. More...

#include <ActuatorForceTargetFast.h>

Inheritance diagram for OpenSim::ActuatorForceTargetFast:

List of all members.

Public Member Functions
virtual	~ActuatorForceTargetFast ()
	Destructor.
	ActuatorForceTargetFast (SimTK::State &s, int aNX, CMC *aController)
	Constructor.
bool	prepareToOptimize (SimTK::State &s, double *x)
int	objectiveFunc (const SimTK::Vector &aF, const bool new_coefficients, SimTK::Real &rP) const
int	gradientFunc (const SimTK::Vector &x, const bool new_coefficients, SimTK::Vector &gradient) const
int	constraintFunc (const SimTK::Vector &x, const bool new_coefficients, SimTK::Vector &constraints) const
	Compute constraint ic given x.
int	constraintJacobian (const SimTK::Vector &x, const bool new_coefficients, SimTK::Matrix &jac) const
	Compute the gradient of constraint i given x.
CMC *	getController ()

---

Detailed Description

A Computed Muscle Control (CMC) optimization target for controlling dynamic systems whose actuators may be themselves governed by differential equations, meaning there may be non-linear behavior and delays in force production.

The performance criterion is the sum of actutor stresses squared. The desired accelerations are achieved by imposing a set of constraints. The desired accelerations are computed according to the Proportional Derivative (PD) control in order to drive the dynamic model toward a set of target kinematic trajectories.

Because the desired accelerations are achieved by imposing a set of linear hard constraints, this optimiztion target can fail if the desired accelreations cannot be achieved. To insure that the constraints can be achieved, a number of sufficiently strong actuators can be added to the model. Althernatively, one can use a different optimization target ActuatorForceTarget. The benefits of using the fast target are both speed and tracking accuracy.

Version:

1.0

Author:

Frank C. Anderson

---

Constructor & Destructor Documentation

ActuatorForceTargetFast::~ActuatorForceTargetFast

(

)

[virtual]

Destructor.

ActuatorForceTargetFast::ActuatorForceTargetFast	(	SimTK::State &	s,
		int	aNX,
		CMC *	aController
	)

Constructor.

Parameters:

	aNX	Number of controls.
	aController	Parent controller.

---

Member Function Documentation

int ActuatorForceTargetFast::constraintFunc	(	const SimTK::Vector &	x,
		const bool	new_coefficients,
		SimTK::Vector &	constraints
	)			const

Compute constraint ic given x.

Note that the indexing starts at 1;

Parameters:

	x	Array of controls.
	ic	Index of the constraint (indexing starts at 1, not 0).
	c	Value of constraint ic.

Returns:

Status (normal termination = 0, error < 0).

int ActuatorForceTargetFast::constraintJacobian	(	const SimTK::Vector &	x,
		const bool	new_coefficients,
		SimTK::Matrix &	jac
	)			const

Compute the gradient of constraint i given x.

Parameters:

	x	Array of controls.
	ic	Index of the constraint (indexing starts at 1, not 0).
	dcdx	Derivative of constraint ic with respect to the controls.

Returns:

Status (normal termination = 0, error < 0).

CMC* OpenSim::ActuatorForceTargetFast::getController

(

)

[inline]

int OpenSim::ActuatorForceTargetFast::gradientFunc	(	const SimTK::Vector &	x,
		const bool	new_coefficients,
		SimTK::Vector &	gradient
	)			const

int OpenSim::ActuatorForceTargetFast::objectiveFunc	(	const SimTK::Vector &	aF,
		const bool	new_coefficients,
		SimTK::Real &	rP
	)			const

bool ActuatorForceTargetFast::prepareToOptimize	(	SimTK::State &	s,
		double *	x
	)			[virtual]

Reimplemented from OpenSim::OptimizationTarget.

---

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

• OpenSim/Tools/ActuatorForceTargetFast.h
• OpenSim/Tools/ActuatorForceTargetFast.cpp