This solver uses the CasADi library (https://casadi.org) to convert the MocoProblem into a generic nonlinear programming problem. More...

Inheritance diagram for OpenSim::MocoCasADiSolver:

Static Public Member Functions
Auto-generated functions
static MocoCasADiSolver *	safeDownCast (OpenSim::Object *obj)
	For use in MATLAB and Python to access the concrete class. More...

Static Public Member Functions inherited from OpenSim::MocoDirectCollocationSolver
static MocoDirectCollocationSolver *	safeDownCast (OpenSim::Object *obj)
	For use in MATLAB and Python to access the concrete class. More...

static const std::string &	getClassName ()
	This returns "MocoDirectCollocationSolver" More...

Static Public Member Functions inherited from OpenSim::MocoSolver
static MocoSolver *	safeDownCast (OpenSim::Object *obj)
	For use in MATLAB and Python to access the concrete class. More...

static const std::string &	getClassName ()
	This returns "MocoSolver" More...

Static Public Member Functions inherited from OpenSim::Object
static void	registerType (const Object &defaultObject)
	Register an instance of a class; if the class is already registered it will be replaced. More...

static void	renameType (const std::string &oldTypeName, const std::string &newTypeName)
	Support versioning by associating the current Object type with an old name. More...

static const Object *	getDefaultInstanceOfType (const std::string &concreteClassName)
	Return a pointer to the default instance of the registered (concrete) Object whose class name is given, or NULL if the type is not registered. More...

template<class T >
static bool	isObjectTypeDerivedFrom (const std::string &concreteClassName)
	Return true if the given concrete object type represents a subclass of the template object type T, and thus could be referenced with a T*. More...

static Object *	newInstanceOfType (const std::string &concreteClassName)
	Create a new instance of the concrete Object type whose class name is given as concreteClassName. More...

static void	getRegisteredTypenames (Array< std::string > &typeNames)
	Retrieve all the typenames registered so far. More...

template<class T >
static void	getRegisteredObjectsOfGivenType (ArrayPtrs< T > &rArray)
	Return an array of pointers to the default instances of all registered (concrete) Object types that derive from a given Object-derived type that does not have to be concrete. More...

static bool	PrintPropertyInfo (std::ostream &os, const std::string &classNameDotPropertyName, bool printFlagInfo=true)
	Dump formatted property information to a given output stream, useful for creating a "help" facility for registered objects. More...

static bool	PrintPropertyInfo (std::ostream &os, const std::string &className, const std::string &propertyName, bool printFlagInfo=true)
	Same as the other signature but the class name and property name are provided as two separate strings. More...

static Object *	makeObjectFromFile (const std::string &fileName)
	Create an OpenSim object whose type is based on the tag at the root node of the XML file passed in. More...

static const std::string &	getClassName ()
	Return the name of this class as a string; i.e., "Object". More...

static void	setSerializeAllDefaults (bool shouldSerializeDefaults)
	Static function to control whether all registered objects and their properties are written to the defaults section of output files rather than only those values for which the default was explicitly overwritten when read in from an input file or set programmatically. More...

static bool	getSerializeAllDefaults ()
	Report the value of the "serialize all defaults" flag. More...

static bool	isKindOf (const char *type)
	Returns true if the passed-in string is "Object"; each Object-derived class defines a method of this name for its own class name. More...

static void	setDebugLevel (int newLevel)
	Set the amount of logging output. More...

static int	getDebugLevel ()
	Get the current setting of debug level. More...

static Object *	SafeCopy (const Object *aObject)
	Use the clone() method to duplicate the given object unless the pointer is null in which case null is returned. More...

static void	RegisterType (const Object &defaultObject)
	OBSOLETE alternate name for registerType(). More...

static void	RenameType (const std::string &oldName, const std::string &newName)
	OBSOLETE alternate name for renameType(). More...

Auto-generated functions <br>
static const std::string &	getClassName ()
	This returns "MocoCasADiSolver" More...

MocoCasADiSolver *	clone () const override
	Create a new heap-allocated copy of the concrete object to which this Object refers. More...

const std::string &	getConcreteClassName () const override
	Returns the class name of the concrete Object-derived class of the actual object referenced by this Object, as a string. More...

Additional Inherited Members
Public Member Functions inherited from OpenSim::MocoDirectCollocationSolver
Public Member Functions inherited from OpenSim::MocoSolver
	MocoSolver ()=default

	MocoSolver (const MocoProblem &problem)
	This calls resetProblem() with the provided problem. More...

virtual	~MocoSolver ()=default

void	resetProblem (const MocoProblem &problem) const
	Call this to prepare the solver for use on the provided problem. More...

MocoTrajectory	createGuessTimeStepping () const
	(Experimental) Run a forward simulation (using the OpenSim Manager, which uses a SimTK::Integrator), using the default controls for actuators and the default states as the initial states, to create a guess that is dynamically consistent (constraint errors should be small). More...

Public Member Functions inherited from OpenSim::Object
virtual	~Object ()
	Virtual destructor for cleanup. More...

bool	isEqualTo (const Object &aObject) const
	Equality operator wrapper for use from languages not supporting operator overloading. More...

Object &	operator= (const Object &aObject)
	Copy assignment copies he base class fields, including the properties. More...

virtual bool	operator== (const Object &aObject) const
	Determine if two objects are equal. More...

virtual bool	operator< (const Object &aObject) const
	Provide an ordering for objects so they can be put in sorted containers. More...

void	setName (const std::string &name)
	Set the name of the Object. More...

const std::string &	getName () const
	Get the name of this Object. More...

void	setDescription (const std::string &description)
	Set description, a one-liner summary. More...

const std::string &	getDescription () const
	Get description, a one-liner summary. More...

const std::string &	getAuthors () const
	Get Authors of this Object. More...

void	setAuthors (const std::string &authors)
	Set Authors of this object. More...

const std::string &	getReferences () const
	Get references or publications to cite if using this object. More...

void	setReferences (const std::string &references)
	Set references or publications to cite if using this object. More...

int	getNumProperties () const
	Determine how many properties are stored with this Object. More...

const AbstractProperty &	getPropertyByIndex (int propertyIndex) const
	Get a const reference to a property by its index number, returned as an AbstractProperty. More...

AbstractProperty &	updPropertyByIndex (int propertyIndex)
	Get a writable reference to a property by its index number, returned as an AbstractProperty. More...

bool	hasProperty (const std::string &name) const
	Return true if this Object has a property of any type with the given name, which must not be empty. More...

const AbstractProperty &	getPropertyByName (const std::string &name) const
	Get a const reference to a property by its name, returned as an AbstractProperty. More...

AbstractProperty &	updPropertyByName (const std::string &name)
	Get a writable reference to a property by its name, returned as an AbstractProperty. More...

template<class T >
bool	hasProperty () const
	Return true if this Object contains an unnamed, one-object property that contains objects of the given template type T. More...

template<class T >
const Property< T > &	getProperty (const PropertyIndex &index) const
	Get property of known type Property<T> as a const reference; the property must be present and have the right type. More...

template<class T >
Property< T > &	updProperty (const PropertyIndex &index)
	Get property of known type Property<T> as a writable reference; the property must be present and have the right type. More...

bool	isObjectUpToDateWithProperties () const
	Returns `true` if no property's value has changed since the last time setObjectIsUpToDateWithProperties() was called. More...

void	readObjectFromXMLNodeOrFile (SimTK::Xml::Element &objectElement, int versionNumber)
	We're given an XML element from which we are to populate this Object. More...

virtual void	updateFromXMLNode (SimTK::Xml::Element &objectElement, int versionNumber)
	Use this method to deserialize an object from a SimTK::Xml::Element. More...

void	updateXMLNode (SimTK::Xml::Element &parent, const AbstractProperty *prop=nullptr) const
	Serialize this object into the XML node that represents it. More...

bool	getInlined () const
	Inlined means an in-memory Object that is not associated with an XMLDocument. More...

void	setInlined (bool aInlined, const std::string &aFileName="")
	Mark this as inlined or not and optionally provide a file name to associate with the new XMLDocument for the non-inline case. More...

std::string	getDocumentFileName () const
	If there is a document associated with this object then return the file name maintained by the document. More...

int	getDocumentFileVersion () const
	If there is a document associated with this object then return its version number. More...

void	setAllPropertiesUseDefault (bool aUseDefault)

bool	print (const std::string &fileName) const
	Write this Object into an XML file of the given name; conventionally the suffix to use is ".osim". More...

std::string	dump () const
	dump the XML representation of this Object into an std::string and return it. More...

virtual bool	isA (const char *type) const
	The default implementation returns true only if the supplied string is "Object"; each Object-derived class overrides this to match its own class name. More...

const std::string &	toString () const
	Wrapper to be used on Java side to display objects in tree; this returns just the object's name. More...

PropertySet &	getPropertySet ()
	OBSOLETE: Get a reference to the PropertySet maintained by the Object. More...

const PropertySet &	getPropertySet () const

Detailed Description

This solver uses the CasADi library (https://casadi.org) to convert the MocoProblem into a generic nonlinear programming problem.

CasADi efficiently calculcates the derivatives required to solve MocoProblems, and may solve your MocoProblem more quickly that MocoTropterSolver. In general, we hope that the feature sets of MocoCasADiSolver and MocoTropterSolver are the same. Note, however, that parameter optimization problems are implemented much less efficiently in this solver; for parameter optimization, first try MocoTropterSolver.

Sparsity

Direct collocation is fast because the derivative matrices (Jacobian and Hessian) in the optimization problem are extremely sparse. By default, CasADi determines the sparsity pattern of these matrices to be block patterns: the individual functions that invoke OpenSim are treated as dense, but this dense pattern is repeated in a sparse way. This is conservative because we ensure that no "nonzeros" are accidentally treated as "zeros." However, the problem may solve faster if we discover more "zeros."

See the optim_sparsity_detection setting for more information. In the case of "random", we use 3 random trajectories and combine the resulting sparsity patterns. The seed used for these 3 random trajectories is always exactly the same, ensuring that the sparsity pattern is deterministic.

To explore the sparsity pattern for your problem, set optim_write_sparsity and run the resulting files with the plot_casadi_sparsity.py Python script.

Finite difference scheme

The "central" finite difference is more accurate but can be 2 times slower than "forward" (tested on exampleSlidingMass). Sometimes, problems may struggle to converge with "forward".

Parallelization

By default, CasADi evaluate the integral cost integrand and the differential-algebraic equations in parallel. This should work fine for almost all models, but if you have custom model components, ensure they are threadsafe. Make sure that threads do not access shared resources like files or global variables at the same time.

You can turn off or change the number of parallel jobs used for individual problems via either the OPENSIM_MOCO_PARALLEL environment variable (see getMocoParallelEnvironmentVariable()) or the parallel property of this class. For example, if you plan to solve two problems at the same time on a machine with 4 processor cores, you could set OPENSIM_MOCO_PARALLEL to 2 to use all 4 cores.

Note that there is overhead in the parallelization; if you plan to solve many problems, it is better to turn off parallelization here and parallelize the solving of your multiple problems using your system (e.g., invoke Moco in multiple Terminals or Command Prompts).

Note that the parallel property overrides the environment variable, allowing more granular control over parallelization. However, the parallelization setting does not logically belong as a property, as it does not affect the solution. We encourage you to use the environment variable instead, as this allows different users to solve the same problem with the parallelization they prefer.

Parameter variables

By default, MocoCasADiSolver is much slower than MocoTroperSolver at handling problems with MocoParameters. Many parameters require invoking Model::initSystem() to take effect, and this function is expensive (for CasADi, we must invoke this function for every time point, while in Tropter, we can invoke the function only once for every NLP iterate). However, if you know that all parameters in your problem do not require Model::initSystem(), you can substantially speed up your optimization by setting the parameters_require_initsystem property to false. Be careful, though: you will end up with incorrect results if your parameter does indeed require Model::initSystem(). To protect against this, ensure that you obtain the same results whether this setting is true or false.

Note: The software license of CasADi (LGPL) is more restrictive than that of the rest of Moco (Apache 2.0).; This solver currently only supports systems for which \( \dot{q} = u \) (e.g., no quaternions).

Member Function Documentation

◆ clone()

MocoCasADiSolver * OpenSim::MocoCasADiSolver::clone ( ) const

inlineoverridevirtual

Create a new heap-allocated copy of the concrete object to which this Object refers.

It is up to the caller to delete the returned object when no longer needed. Every concrete object deriving from Object implements this pure virtual method automatically, via the declaration macro it invokes (e.g., OpenSim_DECLARE_CONCRETE_OBJECT()). Note that the concrete class overrides modify the return type to be a pointer to the concrete object; that still overrides the base class method because the return type is covariant with (that is, derives from) Object.

Implements OpenSim::MocoDirectCollocationSolver.

◆ getClassName()

static const std::string & OpenSim::MocoCasADiSolver::getClassName ( )

inlinestatic

This returns "MocoCasADiSolver"

See getConcreteClassName() if you want the class name of the underlying concrete object instead.

◆ getConcreteClassName()

const std::string & OpenSim::MocoCasADiSolver::getConcreteClassName ( ) const

inlineoverridevirtual

Returns the class name of the concrete Object-derived class of the actual object referenced by this Object, as a string.

This is the string that is used as the tag for this concrete object in an XML file. Every concrete class derived from Object automatically overrides this method via the declaration macro it uses. See getClassName() to get the class name of the referencing (possibly abstract) class rather than the concrete object.

See also: getClassName()

Implements OpenSim::MocoDirectCollocationSolver.

◆ safeDownCast()

static MocoCasADiSolver * OpenSim::MocoCasADiSolver::safeDownCast ( OpenSim::Object * obj )

inlinestatic

For use in MATLAB and Python to access the concrete class.

Example: cObj = MocoCasADiSolver.safeDownCast(obj). This is equivalent to dynamic_cast<MocoCasADiSolver*>(obj) in C++.

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

OpenSim/Moco/MocoCasADiSolver/MocoCasADiSolver.h

Static Public Member Functions

Auto-generated functions <br>

Additional Inherited Members