API  4.1
For C++ developers
OpenSim::Muscle::FiberVelocityInfo Struct Reference

FiberVelocityInfo contains velocity quantities related to the velocity of the muscle (fiber + tendon) complex. More...

Public Member Functions

 FiberVelocityInfo ()

Public Attributes

double fiberVelocity
double fiberVelocityAlongTendon
double normFiberVelocity
double pennationAngularVelocity
double tendonVelocity
double normTendonVelocity
double fiberForceVelocityMultiplier
SimTK::Vector userDefinedVelocityExtras


std::ostream & operator<< (std::ostream &o, const FiberVelocityInfo &fvi)

Detailed Description

FiberVelocityInfo contains velocity quantities related to the velocity of the muscle (fiber + tendon) complex.

The function that populates this struct, calcFiberVelocityInfo, is called when position and velocity information is known. This function is the second function that is called of these related functions:calcMuscleLengthInfo,calcFiberVelocityInfo and calcMuscleDynamicInfo. When calcFiberVelocity is called the acceleration of the muscle path, and any forces the muscle experiences will not be known.

NAME                     DIMENSION             UNITS
 fiberVelocity             length/time           m/s
 fiberVelocityAlongTendon  length/time           m/s       [1]
 normFiberVelocity         (length/time)/Vmax    NA        [2]

 pennationAngularVelocity  angle/time            rad/s     [3]

 tendonVelocity            length/time           m/s       
 normTendonVelocity        (length/time)/length  (m/s)/m   [4]

 fiberForceVelocityMultiplier force/force          NA        [5]

 userDefinedVelocityExtras    NA                   NA      [6]

[1] fiberVelocityAlongTendon is the first derivative of the symbolic equation that defines the fiberLengthAlongTendon.

[2] normFiberVelocity is the fiberVelocity (in m/s) divided by the optimal length of the fiber (in m) and by the maximum fiber velocity (in optimal-fiber-lengths/s). normFiberVelocity has units of 1/optimal-fiber-length.

[3] The sign of the angular velocity is defined using the right hand rule.

[4] normTendonVelocity is the tendonVelocity (the lengthening velocity of the tendon) divided by its resting length

[5] The fiberForceVelocityMultiplier is the scaling factor that represents how a muscle fiber's force generating capacity is modulated by the contraction (concentric or eccentric) velocity of the fiber. Generally this curve has a value of 1 at a fiber velocity of 0, has a value of between 1.4-1.8 at the maximum eccentric contraction velocity and a value of 0 at the maximum concentric contraction velocity. The force velocity curve, which computes this term, is usually an interpolation of an experimental curve.

[6] This vector is left for the muscle modeler to populate with any computationally expensive quantities that are computed in calcFiberVelocityInfo, and required for use in the user defined function calcMuscleDynamicsInfo. None of the parent classes make any assumptions about what is or isn't in this field

  • use as necessary.

Constructor & Destructor Documentation

◆ FiberVelocityInfo()

OpenSim::Muscle::FiberVelocityInfo::FiberVelocityInfo ( )

Friends And Related Function Documentation

◆ operator<<

std::ostream& operator<< ( std::ostream &  o,
const FiberVelocityInfo fvi 

Member Data Documentation

◆ fiberForceVelocityMultiplier

double OpenSim::Muscle::FiberVelocityInfo::fiberForceVelocityMultiplier

◆ fiberVelocity

double OpenSim::Muscle::FiberVelocityInfo::fiberVelocity

◆ fiberVelocityAlongTendon

double OpenSim::Muscle::FiberVelocityInfo::fiberVelocityAlongTendon

◆ normFiberVelocity

double OpenSim::Muscle::FiberVelocityInfo::normFiberVelocity

◆ normTendonVelocity

double OpenSim::Muscle::FiberVelocityInfo::normTendonVelocity

◆ pennationAngularVelocity

double OpenSim::Muscle::FiberVelocityInfo::pennationAngularVelocity

◆ tendonVelocity

double OpenSim::Muscle::FiberVelocityInfo::tendonVelocity

◆ userDefinedVelocityExtras

SimTK::Vector OpenSim::Muscle::FiberVelocityInfo::userDefinedVelocityExtras

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