API  4.3
For MATLAB, Python, Java, and C++ users
OpenSim::MocoStepLengthAsymmetryGoal Class Reference

Minimize the error between a model's step time asymmetry and a specified target asymmetry value over a gait cycle. More...

+ Inheritance diagram for OpenSim::MocoStepLengthAsymmetryGoal:

OpenSim Properties, Sockets, Outputs, Inputs

Properties (single-value)
std::string left_foot_frame
 "The model frame associated with the left foot." More...
 
std::string right_foot_frame
 "The model frame associated with the right foot." More...
 
double target_asymmetry
 "The target asymmetry value, between -1.0 and 1.0. Positive " "asymmetry is associated with the right leg, and negative asymmetry " "for the left. Default: 0" More...
 
double asymmetry_smoothing
 "The value that determines the smoothing of the asymmetry " "computation. Larger values mean that larger step length errors are " "required for a step to be counted towards the asymmetry error. " "Default: 5." More...
 
double stride_length
 "The known stride length of the simulation, in meters." "Default is -1; the user must provide a positive value." More...
 
std::string walking_direction
 "The walking direction of the model in the ground frame, which " "is used to determine the leading foot during double support. " "Acceptable direction values include 'positive-x', 'positive-y', " "'positive-z', 'negative-x', 'negative-y', and 'negative-z'. " "Default: 'positive-x'." More...
 
- OpenSim Properties, Sockets, Outputs, Inputs inherited from OpenSim::MocoGoal
bool enabled
 "This bool indicates whether this goal is enabled." More...
 
double weight
 "In cost mode, the goal is multiplied by this weight (default: " "1)." More...
 
std::string mode
 "'cost' to enforce as a penalty, 'endpoint_constraint' to enforce " "as a constraint." More...
 
MocoConstraintInfo MocoConstraintInfo
 "The bounds and labels for this MocoGoal, if applied as an " "endpoint constraint." More...
 
MocoScaleFactor scale_factors
 "Scale factors added by derived MocoGoal classes that are optimized " "via a MocoParameter. A copy of each MocoScaleFactor component is " "added to the model internal to MocoProblem, which makes the scale " "factors values available when computing the cost function for each " "MocoGoal." More...
 

Public Member Functions

 MocoStepLengthAsymmetryGoal ()
 
 MocoStepLengthAsymmetryGoal (std::string name)
 
 MocoStepLengthAsymmetryGoal (std::string name, double weight)
 
void setLeftFootFrame (const std::string &frame)
 Set the body frame associated with the left foot. More...
 
std::string getLeftFootFrame ()
 
void setRightFootFrame (const std::string &frame)
 Set the body frame associated with the right foot. More...
 
std::string getRightFootFrame ()
 
void setTargetAsymmetry (double asymmetry)
 Set the asymmetry value targeted by this goal. More...
 
double getTargetAsymmetry ()
 
void setStrideLength (double length)
 Set the known stride length of your walking simulation. More...
 
double getStrideLength ()
 
void setWalkingDirection (const std::string &direction)
 Set the walking direction of the model in the ground frame, which is used to compute step lengths. More...
 
std::string getWalkingDirection ()
 
void setAsymmetrySmoothing (double smoothing)
 Set the values that determines the smoothing of the asymmetry computation. More...
 
double getAsymmetrySmoothing ()
 
- Public Member Functions inherited from OpenSim::MocoGoal
 MocoGoal ()
 
 MocoGoal (std::string name)
 
 MocoGoal (std::string name, double weight)
 
void setEnabled (bool enabled)
 Set whether this goal is used in the problem. More...
 
bool getEnabled () const
 
void setWeight (double weight)
 In cost mode, the goal is multiplied by this weight. More...
 
double getWeight () const
 
void setMode (std::string mode)
 Set the mode property to either 'cost' or 'endpoint_constraint'. More...
 
std::string getModeAsString () const
 This returns the default mode of the goal, unless the user overrode the default using setMode(). More...
 
Mode getMode () const
 
bool getModeIsCost () const
 
bool getModeIsEndpointConstraint () const
 
Mode getDefaultMode () const
 Types of goals have a class-level default for whether they are enforced as a cost or endpoint constraint. More...
 
bool getSupportsEndpointConstraint () const
 Can this goal be used in endpoint constraint mode? More...
 
const MocoConstraintInfogetConstraintInfo () const
 Get bounds for the constraints that are enforced when using this goal in endpoint constraint mode. More...
 
MocoConstraintInfoupdConstraintInfo ()
 
int getNumOutputs () const
 Get the length of the return value of calcGoal(). More...
 
int getNumIntegrals () const
 Get the number of integrals required by this cost. More...
 
SimTK::Stage getStageDependency () const
 Obtain the stage that this goal depends on. More...
 
SimTK::Real calcIntegrand (const IntegrandInput &input) const
 Calculate the integrand that should be integrated and passed to calcCost(). More...
 
void calcGoal (const GoalInput &input, SimTK::Vector &goal) const
 In cost mode, the returned cost includes the weight, and the elements of the returned vector should be summed by the caller to obtain the total cost. More...
 
void initializeOnModel (const Model &model) const
 Perform error checks on user input for this goal, and cache quantities needed when computing the goal value. More...
 
std::vector< MocoScaleFactorgetScaleFactors () const
 Get a vector of the MocoScaleFactors added to this MocoGoal. More...
 
void printDescription () const
 Print the name type and mode of this goal. 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...
 
Objectoperator= (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 AbstractPropertygetPropertyByIndex (int propertyIndex) const
 Get a const reference to a property by its index number, returned as an AbstractProperty. More...
 
AbstractPropertyupdPropertyByIndex (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 AbstractPropertygetPropertyByName (const std::string &name) const
 Get a const reference to a property by its name, returned as an AbstractProperty. More...
 
AbstractPropertyupdPropertyByName (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...
 
PropertySetgetPropertySet ()
 OBSOLETE: Get a reference to the PropertySet maintained by the Object. More...
 
const PropertySetgetPropertySet () const
 

Auto-generated functions

static MocoStepLengthAsymmetryGoalsafeDownCast (OpenSim::Object *obj)
 For use in MATLAB and Python to access the concrete class. More...
 
static const std::string & getClassName ()
 This returns "MocoStepLengthAsymmetryGoal". More...
 
MocoStepLengthAsymmetryGoalclone () 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

- Static Public Member Functions inherited from OpenSim::MocoGoal
static MocoGoalsafeDownCast (OpenSim::Object *obj)
 For use in MATLAB and Python to access the concrete class. More...
 
static const std::string & getClassName ()
 This returns "MocoGoal". 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 ObjectgetDefaultInstanceOfType (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 ObjectnewInstanceOfType (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 ObjectmakeObjectFromFile (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 ObjectSafeCopy (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...
 

Detailed Description

Minimize the error between a model's step time asymmetry and a specified target asymmetry value over a gait cycle.

Step Length Asymmetry (SLA) is a ratio and is calculated as follows: The Right Step Length (RSL) is the distance between feet at right foot strike The Left Step Length (LSL) is the distance between feet at left foot strike Step Length Asymmetry = (RSL - LSL) / (RSL + LSL)

In this goal, the distance between feet, or "foot frames", is limited throughout the gait cycle. The goal calculates the distance between the left foot and right foot, then limits the distance between feet to not pass beyond minimum (negative) or maximum (positive) bounds. There are two limits used: one that limits the distance between feet when the right foot is in front, and one that limits the distance between feet when the left foot is in front.

Users must provide the target asymmetry value via 'setTargetAsymmetry()'. Asymmetry values ranges from -1.0 to 1.0. For example, 0.20 is 20% positive step length asymmetry with greater right step length than left step length. A symmetric step length solution can be achieved by setting this property to zero. This goal can be used only in 'cost' mode. To make this goal suitable for gradient-based optimization, step length values are assigned via a smoothing function which can be controlled via 'setAsymmetrySmoothing()'.

Users must also prescribe the stride length via 'setStrideLength()'. The goal then calculates the minimum and maximum bounds on the distance between right and left foot. Users must ensure that this stride length is met via problem bounds or other goals; the value provided to MocoStepLengthAsymmetryGoal is only used to compute the model's asymmetry in the cost function.

Note
This goal is designed for simulations of bipedal gait.
Since this goal approximates step length asymmetry, users should calculate the true asymmetry value after running an optimization.

Constructor & Destructor Documentation

◆ MocoStepLengthAsymmetryGoal() [1/3]

OpenSim::MocoStepLengthAsymmetryGoal::MocoStepLengthAsymmetryGoal ( )
inline

◆ MocoStepLengthAsymmetryGoal() [2/3]

OpenSim::MocoStepLengthAsymmetryGoal::MocoStepLengthAsymmetryGoal ( std::string  name)
inline

◆ MocoStepLengthAsymmetryGoal() [3/3]

OpenSim::MocoStepLengthAsymmetryGoal::MocoStepLengthAsymmetryGoal ( std::string  name,
double  weight 
)
inline

Member Function Documentation

◆ calcGoalImpl()

void OpenSim::MocoStepLengthAsymmetryGoal::calcGoalImpl ( const GoalInput input,
SimTK::Vector &  goal 
) const
overrideprotectedvirtual

You may need to realize the state to the stage required for your calculations.

Do NOT realize to a stage higher than the goal's stage dependency; doing so will cause an exception to be thrown. The Lagrange multipliers for kinematic constraints are not available.

Implements OpenSim::MocoGoal.

◆ calcIntegrandImpl()

void OpenSim::MocoStepLengthAsymmetryGoal::calcIntegrandImpl ( const IntegrandInput input,
double &  integrand 
) const
overrideprotected

◆ clone()

MocoStepLengthAsymmetryGoal* OpenSim::MocoStepLengthAsymmetryGoal::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::MocoGoal.

◆ getAsymmetrySmoothing()

double OpenSim::MocoStepLengthAsymmetryGoal::getAsymmetrySmoothing ( )
inline

◆ getClassName()

static const std::string& OpenSim::MocoStepLengthAsymmetryGoal::getClassName ( )
inlinestatic

This returns "MocoStepLengthAsymmetryGoal".

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

◆ getConcreteClassName()

const std::string& OpenSim::MocoStepLengthAsymmetryGoal::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::MocoGoal.

◆ getLeftFootFrame()

std::string OpenSim::MocoStepLengthAsymmetryGoal::getLeftFootFrame ( )
inline

◆ getRightFootFrame()

std::string OpenSim::MocoStepLengthAsymmetryGoal::getRightFootFrame ( )
inline

◆ getStrideLength()

double OpenSim::MocoStepLengthAsymmetryGoal::getStrideLength ( )
inline

◆ getTargetAsymmetry()

double OpenSim::MocoStepLengthAsymmetryGoal::getTargetAsymmetry ( )
inline

◆ getWalkingDirection()

std::string OpenSim::MocoStepLengthAsymmetryGoal::getWalkingDirection ( )
inline

◆ initializeOnModelImpl()

void OpenSim::MocoStepLengthAsymmetryGoal::initializeOnModelImpl ( const Model ) const
overrideprotectedvirtual

Perform any caching before the problem is solved.

You must override this function and invoke setRequirements().

Precondition(s):
The model is initialized (initSystem()) and getModel() is available. The passed-in model is equivalent to getModel(). Use this opportunity to check for errors in user input.

Implements OpenSim::MocoGoal.

◆ printDescriptionImpl()

void OpenSim::MocoStepLengthAsymmetryGoal::printDescriptionImpl ( ) const
overrideprotectedvirtual

Print a more detailed description unique to each goal.

Reimplemented from OpenSim::MocoGoal.

◆ safeDownCast()

static MocoStepLengthAsymmetryGoal* OpenSim::MocoStepLengthAsymmetryGoal::safeDownCast ( OpenSim::Object obj)
inlinestatic

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

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

◆ setAsymmetrySmoothing()

void OpenSim::MocoStepLengthAsymmetryGoal::setAsymmetrySmoothing ( double  smoothing)
inline

Set the values that determines the smoothing of the asymmetry computation.

This term is necessary since this computation is non-smooth. Larger smoothing values mean that larger step length errors are required for a given step to be counted towards the total asymmetry error minimized in the cost.

◆ setLeftFootFrame()

void OpenSim::MocoStepLengthAsymmetryGoal::setLeftFootFrame ( const std::string &  frame)
inline

Set the body frame associated with the left foot.

◆ setRightFootFrame()

void OpenSim::MocoStepLengthAsymmetryGoal::setRightFootFrame ( const std::string &  frame)
inline

Set the body frame associated with the right foot.

◆ setStrideLength()

void OpenSim::MocoStepLengthAsymmetryGoal::setStrideLength ( double  length)
inline

Set the known stride length of your walking simulation.

This value is necessary to compute step length asymmetry.

◆ setTargetAsymmetry()

void OpenSim::MocoStepLengthAsymmetryGoal::setTargetAsymmetry ( double  asymmetry)
inline

Set the asymmetry value targeted by this goal.

The error between the target asymmetry and the model asymmetry is squared in the integrand.

◆ setWalkingDirection()

void OpenSim::MocoStepLengthAsymmetryGoal::setWalkingDirection ( const std::string &  direction)
inline

Set the walking direction of the model in the ground frame, which is used to compute step lengths.

Acceptable direction values include "positive-x", "positive-y", "positive-z", "negative-x", "negative-y", and "negative-z". Default: "positive-x".

OpenSim Property, Socket, Output, Input Documentation

◆ asymmetry_smoothing

double OpenSim::MocoStepLengthAsymmetryGoal::asymmetry_smoothing

"The value that determines the smoothing of the asymmetry " "computation. Larger values mean that larger step length errors are " "required for a step to be counted towards the asymmetry error. " "Default: 5."

This property appears in XML files under the tag <asymmetry_smoothing>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_asymmetry_smoothing(), upd_asymmetry_smoothing(), set_asymmetry_smoothing()

◆ left_foot_frame

std::string OpenSim::MocoStepLengthAsymmetryGoal::left_foot_frame

"The model frame associated with the left foot."

This property appears in XML files under the tag <left_foot_frame>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_left_foot_frame(), upd_left_foot_frame(), set_left_foot_frame()

◆ right_foot_frame

std::string OpenSim::MocoStepLengthAsymmetryGoal::right_foot_frame

"The model frame associated with the right foot."

This property appears in XML files under the tag <right_foot_frame>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_right_foot_frame(), upd_right_foot_frame(), set_right_foot_frame()

◆ stride_length

double OpenSim::MocoStepLengthAsymmetryGoal::stride_length

"The known stride length of the simulation, in meters." "Default is -1; the user must provide a positive value."

This property appears in XML files under the tag <stride_length>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_stride_length(), upd_stride_length(), set_stride_length()

◆ target_asymmetry

double OpenSim::MocoStepLengthAsymmetryGoal::target_asymmetry

"The target asymmetry value, between -1.0 and 1.0. Positive " "asymmetry is associated with the right leg, and negative asymmetry " "for the left. Default: 0"

This property appears in XML files under the tag <target_asymmetry>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_target_asymmetry(), upd_target_asymmetry(), set_target_asymmetry()

◆ walking_direction

std::string OpenSim::MocoStepLengthAsymmetryGoal::walking_direction

"The walking direction of the model in the ground frame, which " "is used to determine the leading foot during double support. " "Acceptable direction values include 'positive-x', 'positive-y', " "'positive-z', 'negative-x', 'negative-y', and 'negative-z'. " "Default: 'positive-x'."

This property appears in XML files under the tag <walking_direction>. This property was generated with the OpenSim_DECLARE_PROPERTY macro; see Property to learn about the property system.

See also
get_walking_direction(), upd_walking_direction(), set_walking_direction()

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