1103 lines
51 KiB
C++
1103 lines
51 KiB
C++
#ifndef MILLARD2016TORQUEMUSCLE_H_
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#define MILLARD2016TORQUEMUSCLE_H_
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/*
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* RBDL - Rigid Body Dynamics Library: Addon : forceElements
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* Copyright (c) 2016 Matthew Millard <matthew.millard@iwr.uni-heidelberg.de>
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*
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* Licensed under the zlib license. See LICENSE for more details.
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*/
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#include <vector>
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#include <rbdl/rbdl_math.h>
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#include "../geometry/SmoothSegmentedFunction.h"
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namespace RigidBodyDynamics {
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namespace Addons {
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namespace Muscle{
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/**
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This struct contains an enumerated list of the data sets which
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constain torque muscles. Thus far this list includes
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-Anderson2007: Table 3 from Anderson et al.
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-Gymnast: A set of torque muscles for the whole body (in progress)
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For details of these data sets please refer to the main description
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of this class.
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*/
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const static struct DataSet{
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enum item{
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Anderson2007 = 0,
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Gymnast,
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Last
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};
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const static char* names[];
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DataSet(){}
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} DataSet;
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/**
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This struct contains an enumerated list of the genders for which
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data torque data has been reported.
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*/
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const static struct GenderSet{
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enum item {
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Male = 0,
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Female,
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Last
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};
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const static char* names[];
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GenderSet(){}
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} GenderSet;
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/**
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This struct contains an enumerated list of the age groups for which
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data torque data has been reported.
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*/
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const static struct AgeGroupSet{
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enum item {
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Young18To25 = 0,
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Middle55To65,
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SeniorOver65,
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Last
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};
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const static char* names[];
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AgeGroupSet(){}
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} AgeGroupSet;
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/**
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This struct contains an enumerated list of the joint-torque-directions
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for which data torque data has been reported.
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*/
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const static struct JointTorqueSet{
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enum item{
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HipExtension = 0,
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HipFlexion = 1,
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KneeExtension = 2,
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KneeFlexion = 3,
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AnkleExtension = 4,
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AnkleFlexion = 5,
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ElbowExtension = 6,
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ElbowFlexion = 7,
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ShoulderExtension = 8,
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ShoulderFlexion = 9,
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WristExtension = 10,
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WristFlexion = 11,
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ShoulderHorizontalAdduction = 12,
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ShoulderHorizontalAbduction = 13,
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ShoulderInternalRotation = 14,
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ShoulderExternalRotation = 15,
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WristUlnarDeviation = 16,
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WristRadialDeviation = 17,
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WristPronation = 18,
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WristSupination = 19,
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LumbarExtension = 20,
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LumbarFlexion = 21,
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Last = 22
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};
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const static char* names[];
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JointTorqueSet(){}
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} JointTorqueSet;
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/**
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This struct contains 3 enumerated lists (Gender, AgeGroup,
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JointTorque) that lists the genders, age groups, and
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joint-torque-directions for which the Anderson2007 data set contains
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data. Please refer to the class description for more details about
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this data set and how to use it.
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*/
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const static struct Anderson2007{
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enum Gender {
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Male = GenderSet::Male,
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Female = GenderSet::Female,
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LastGender
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};
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enum AgeGroup {
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Young18To25 = AgeGroupSet::Young18To25,
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Middle55To65 = AgeGroupSet::Middle55To65,
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SeniorOver65 = AgeGroupSet::SeniorOver65,
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LastAgeGroup
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};
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enum JointTorque{
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HipExtension = JointTorqueSet::HipExtension ,
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HipFlexion = JointTorqueSet::HipFlexion ,
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KneeExtension = JointTorqueSet::KneeExtension ,
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KneeFlexion = JointTorqueSet::KneeFlexion ,
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AnkleExtension = JointTorqueSet::AnkleExtension,
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AnkleFlexion = JointTorqueSet::AnkleFlexion,
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LastJointTorque
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};
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const static char* GenderNames[];
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const static char* AgeGroupNames[];
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const static char* JointTorqueNames[];
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Anderson2007(){}
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} Anderson2007;
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/**
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This struct contains 3 enumerated lists (Gender, AgeGroup,
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JointTorque) that lists the genders, age groups, and
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joint-torque-directions for which the Gymnast data set contains
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data. At the present time Gymnast data set only contains data
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appropriate for a young (18-25) elite male gymnast. Please refer
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to the main class description for details on this data set and how
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to use it.
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*/
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const static struct Gymnast{
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enum Gender {
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Male = GenderSet::Male,
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LastGender
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};
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enum AgeGroup {
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Young18To25 = AgeGroupSet::Young18To25,
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LastAgeGroup
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};
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enum TableIndex {
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TauMax = 0,
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OmegaMax,
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ActiveAngleAtOneNormTorque,
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ActiveAngularStandardDeviation,
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TvAtMaxEccentricVelocity,
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TvAtHalfMaxConcentricVelocity,
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PassiveAngleAtZeroTorque,
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PassiveAngleAtOneNormTorque,
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LastTableIndex
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};
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enum JointTorque {
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HipExtension = JointTorqueSet::HipExtension ,
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HipFlexion = JointTorqueSet::HipFlexion ,
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KneeExtension = JointTorqueSet::KneeExtension ,
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KneeFlexion = JointTorqueSet::KneeFlexion ,
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AnkleExtension = JointTorqueSet::AnkleExtension ,
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AnkleFlexion = JointTorqueSet::AnkleFlexion ,
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ElbowExtension = JointTorqueSet::ElbowExtension ,
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ElbowFlexion = JointTorqueSet::ElbowFlexion ,
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ShoulderExtension = JointTorqueSet::ShoulderExtension ,
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ShoulderFlexion = JointTorqueSet::ShoulderFlexion ,
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WristExtension = JointTorqueSet::WristExtension ,
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WristFlexion = JointTorqueSet::WristFlexion ,
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ShoulderHorizontalAdduction =
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JointTorqueSet::ShoulderHorizontalAdduction,
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ShoulderHorizontalAbduction =
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JointTorqueSet::ShoulderHorizontalAbduction,
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ShoulderInternalRotation =
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JointTorqueSet::ShoulderInternalRotation ,
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ShoulderExternalRotation =
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JointTorqueSet::ShoulderExternalRotation ,
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WristUlnarDeviation = JointTorqueSet::WristUlnarDeviation ,
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WristRadialDeviation = JointTorqueSet::WristRadialDeviation,
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WristPronation = JointTorqueSet::WristPronation ,
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WristSupination = JointTorqueSet::WristSupination ,
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LumbarExtension = JointTorqueSet::LumbarExtension,
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LumbarFlexion = JointTorqueSet::LumbarFlexion,
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LastJointTorque
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};
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const static char* GenderNames[];
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const static char* AgeGroupNames[];
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const static char* JointTorqueNames[];
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Gymnast(){}
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} Gymnast;
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/**
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This is a struct that contains subject-specific information that
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does not change for a given subject.
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@param gender
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Male/Female. Selecting a gender that
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is not present in a data set will result in
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the program aborting and an error message
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being printed to the terminal.
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@param ageGroup:
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Presently the age group options include Young (18-25),
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middle aged (55-65), and senior (>65). Selecting an
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age group that is not present in a data set will result
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in the program aborting and an error message
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being printed to the terminal.
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@param subjectHeightInMeters
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This parameter is used to scale from the normalized
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curves reported by Anderson et al.
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See the class description for details.
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@param subjectMassInKg
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This parameter is used to scale from the normalized
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curves reported by Anderson et al.
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See the class description for details.
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*/
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struct SubjectInformation{
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GenderSet::item gender;
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AgeGroupSet::item ageGroup;
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double heightInMeters;
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double massInKg;
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};
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struct TorqueMuscleInfo{
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/**The angle of the joint (radians)*/
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double jointAngle;
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/**The angular velocity of the joint, where the sign convention
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is chosen by the user at the time the torque muscle is created
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(radians/sec)*/
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double jointAngularVelocity;
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/**The angle that the muscle fiber spans (radians)*/
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double fiberAngle;
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//The angle that the tendon spans (radians)
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//double tendonAngle;
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/**The rate-of-angular-lengthening of the fiber.
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A positive sign is for a concentric contraction,
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that is where the fibers are shortening. (radians/sec)*/
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double fiberAngularVelocity;
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/*The rate-of-angular-lengthening of the tendon.
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A positive sign is for a concentric contraction,
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that is where the tendon is shortening. (radians/sec)*/
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//double tendonAngularVelocity;
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/** The normalized value of the passive-torque-angle curve.
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Here a value of 1 means 1 maximum-isometric-torque. (Nm/Nm)*/
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double fiberPassiveTorqueAngleMultiplier;
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/**The normalized value of the active-torque-angle curve.
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Here a value of 1 means 1 maximum-isometric-torque. (Nm/Nm)*/
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double fiberActiveTorqueAngleMultiplier;
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/**The normalized value of the torque-angular-velocity curve.
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Here a value of 1 means 1 maximum-isometric-torque. (Nm/Nm)*/
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double fiberActiveTorqueAngularVelocityMultiplier;
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/*The normalized value of the tendon-torque-angle curve.
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Here a value of 1 means 1 maximum-isometric-torque. (Nm/Nm)*/
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//double tendonTorqueAngleMultiplier;
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/**The activation of the muscle*/
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double activation;
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/**The torque generated by the active element of the muscle
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fiber (Nm)*/
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double fiberActiveTorque;
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/**The torque generated by the passive element of the muscle
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fiber (Nm)*/
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double fiberPassiveTorque;
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/**The torque generated by the damping element (Nm)*/
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double fiberDampingTorque;
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/**The torque generated by the damping element (Nm)*/
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double fiberNormDampingTorque;
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/**The torque generated by the entire fiber (Nm)*/
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double fiberTorque;
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/*The torque transmitted through the tendon across the joint (Nm)*/
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//double tendonTorque;
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/**The joint torque developed by the muscle. This is signed so
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that it is consistent with the sign convention of the joint
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chosen by the user. (Nm)*/
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double jointTorque;
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/**The stiffness of the fiber (Nm/rad)*/
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double fiberStiffness;
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/*The stiffness of the tendon (Nm/rad)*/
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//double tendonStiffness;
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/** The stiffness of the joint. This is signed so
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that it is consistent with the sign convention of the joint
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chosen by the user. (Nm/rad)*/
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double jointStiffness;
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/**The power output of the active fiber element. A positive
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power means that the fiber is contracting concentrically.
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(Watts - Nm/s)*/
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double fiberActivePower;
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/**The power output of the passive fiber element. A positive
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power means that the passive element is recoiling concentrically
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(Watts - Nm/s)*/
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double fiberPassivePower;
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/**The total power output of the fiber element.(Watts - Nm/s)*/
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double fiberPower;
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/**The partial derivative of joint torque w.r.t the joint angle*/
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double DjointTorqueDjointAngle;
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/**The partial derivative of joint torque w.r.t the joint
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angular velocity*/
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double DjointTorqueDjointAngularVelocity;
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/**The partial derivative of joint torque w.r.t activation*/
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double DjointTorqueDactivation;
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/*The power output of the tendon. A positive power means that
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the tendon is physically shortening. (Watts - Nm/s)*/
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//double tendonPower;
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/** The power output by this muscle at the joint. This is
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signed so that it is consistent with the sign convention of the
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joint chosen by the user. (Nm/rad)*/
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double jointPower;
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TorqueMuscleInfo():
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jointAngle(nan("1")),
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jointAngularVelocity(nan("1")),
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fiberAngle(nan("1")),
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fiberAngularVelocity(nan("1")),
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fiberPassiveTorqueAngleMultiplier(nan("1")),
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fiberActiveTorqueAngleMultiplier(nan("1")),
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fiberActiveTorqueAngularVelocityMultiplier(nan("1")),
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activation(nan("1")),
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fiberActiveTorque(nan("1")),
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fiberPassiveTorque(nan("1")),
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fiberTorque(nan("1")),
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jointTorque(nan("1")),
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fiberStiffness(nan("1")),
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jointStiffness(nan("1")),
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fiberActivePower(nan("1")),
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fiberPassivePower(nan("1")),
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fiberPower(nan("1")),
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jointPower(nan("1")){}
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};
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/**
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This class implements a rigid-tendon torque muscle for a growing
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list of joints and torque-directions. This rigid-tendon torque
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muscle model provides modeling support for 3 phenomena
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-torque-angle curve (\f$\mathbf{t}_A(\theta)\f$): the variation of active isometric torque in one direction as a function of joint angle
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-torque-velocity curve (\f$\mathbf{t}_V(\dot{\theta})\f$): the variation of torque as a function of angular velocity
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-passive-torque-angle curve (\f$s_P\mathbf{t}_P(\theta-\theta_S)\f$): the variation of passive torque as a function of joint angle. Here \f$s_P\f$ and \f$\theta_S\f$ are user-defined scaling and shift parameters.
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each of which are represented as smooth normalized curves that
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vary between 0 and 1. These three phenomena are used to compute the
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torque developed \f$\tau\f$ given the angle of the joint
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\f$\theta\f$, the angular-velocity of the joint \f$\dot{\theta}\f$,
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and the activation of the muscle \f$\mathbf{a}\f$ (a 0-1 quantity
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that defines how much the muscle is turned-on, or activated), and
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the maximum-isometric torque \f$\tau_{ISO}\f$
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\f[
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\tau (\mathbf{a}, \theta,\dot{\theta}) =
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\begin{cases}
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\tau_{ISO} ( \mathbf{a} \, \mathbf{t}_A(\theta) \mathbf{t}_V(\dot{\theta}/\dot{\theta}_{MAX})
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- \beta \dot{\theta}/\dot{\theta}_{MAX}
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+ s_P \mathbf{t}_P(\theta-\theta_S) \, ) & \text{ if } \,\, \tau (\mathbf{a}, \theta,\dot{\theta}) > 0 \\
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0 & \text{otherwise} \end{cases}
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\f]
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The
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This model does not yet provide support for the following phenomena
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but will in the future.
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-activation dynamics: this is to be decided by the modeler.
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-tendon-elasticity
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-muscle short-range-stiffness
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All of these characteristic curves are represented using \f$C_2\f$
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continuous \f$5^{th}\f$ order Bezier curves that have been fitted to
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the data from data in the literature. In many cases these
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curves have been carefully edited so that they fit the curves of
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the original papers, but have more desireable numerical properties
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for optimal control work. The characterisic curves provided by this
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class have been fitted to a growing list of data sets:
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-Anderson Data Set: from Anderson et al. 2007
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-Whole-body Gymnast Data Set: from Jackson, Kentel et al., Anderson et al., Dolan et al. and Raschke et al.
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<b>Data Set: Anderson2007</b>
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This data set uses the mean value of the coefficients published
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in Anderson et al. The standard deviation table has also been
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entered. However, since it is unclear how to use the standard
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deviation in a consistent way across all joints/parameters this
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table is not yet accessible through the constructor. This data
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set includes coefficients for the following
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-Number of subjects: 34
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-Gender: male and female
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-Age: young (18-25, 14 subjects), middle-aged (55-65, 14 subjects), senior (> 65, 6 subjects)
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-Joint: hip/knee/ankle
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-Direction: extension/flexion
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<b>Notes</b>
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-# Angles are plotted using units of degrees for readability. The
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actual curves are described in units of radians
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-# See Anderson et al. for further details.
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\image html fig_MuscleAddon_Anderson2007AllPositiveSigns.png "Characteristic from Anderson et al. 2007 [1]"
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<b>Data Set: Gymnast</b>
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This data set is an attempt at making enough torque muscles for a
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whole body. Since no single source in the literature comes close to
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measuring the characteristics of all of the joints, data from
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Jackson et al., Kentel et al., Anderson et al., Dolan et al, and
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Raschke et al.
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have been combined. Since the subjects used in these various studies
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are wildly different (Jackson et al. measured an elite male gymnast;
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Kentel et al. measured an elite tennis player; Anderson et al. measured,
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in the category of young male, a selection of active undergraduate
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students, Dolan et al from 126 women and 23 men, and Raschke from 5
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male subjects) scaling has been used to make the strength of the subject
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consistent. Scaling coefficients for the lower body, shoulders and
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elbow, and forearm/wrist using measurements that overlapped between
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datasets. Presently this data set includes curves for 22 joint and
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direction specific torque muscles.
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- Number of subjects: 1 elite gymnast (69.6 kg, 1.732 m)
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- Gender: male
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- Age: 21 years old
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- Joint and Directions available
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-# Ankle: flexion/extension (scaled from Anderson)
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-# Knee: flexion/extension (from Jackson)
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-# Hip: flexion/extension (from Jackson)
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-# Lumbar: active extension curves (\f$\mathbf{t}_A\f$ and \f$\mathbf{t}_P\f$) from Raschke et al. passive extension from Dolan et al.
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-# Lumbar: active flexion \f$\tau_{ISO}\f$ from Beimborn et al.
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-# Shoulder: flexion/extension (from Jackson)
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-# Shoulder: horizontal adduction/abduction (from Kentel, scaled to Jackson's subject)
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-# Shoulder: internal rotation/external rotation (from Kentel, scaled to Jackson's subject)
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-# Elbow: flexion/extension (from Kentel, scaled to Jackson's subject)
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-# Wrist: pronation/supination (from Kentel, scaled to Jackson's subject)
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-# Wrist: extension/flextion (from Jackson)
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-# Wrist: ulnar/radial deviation (from Kentel, scaled to Jackson's subject)
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- Missing Joint and directions
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-# Ankle inversion/eversion
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-# Hip adduction/abduction
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-# Hip internal rotation/external rotation
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-# Lumbar extension/flexion
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-# Lumbar bending
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-# Lumbar twisting
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-# Shoulder Adduction
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-# Shoulder Abduction
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-# Scapular elevation/depression
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-# Scapular adduction/abduction
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-# Scapular upward/downward rotation
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In all cases the curves have been fitted to Bezier curves that
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are constructed using functions in TorqueMuscleFunctionFactory.
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<b>Notes</b>
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-# Angles are plotted using units of degrees for readability. The actual curves are described in units of radians
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-# Hip and Knee characteristics taken from Jackson. Ankle extension is from Anderson et al., scaled using Jackson-to-Anderson hip/knee strength ratios from Jackson ratios
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-# Shoulder horizontal adduction/abduction and internal/external rotation is a scaled version of the Kentel. Strength was scaled using the Jackson-to-Kentel shoulder flex/ext ratios.
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-# Elbow extension/flexion and forearm pronation/supination. Elbow strength scaled from Kentel using the ratio of maximum isometric shoulder ext/flextion between Kentel and Jackson. Forearm pronation/supination scaled using the maximum torque strength ratio of wrist extension/flextion between Kentel and Jackson
|
|
-# Wrist ext/flexion directly from Jackson, while the curves for ulnar and radial deviation have been scaled (using the maximum isometric torque ratios of wrist extension and flexion from both models) from Kentel et al.
|
|
-# Lumbar-extension active-torque-angle-curve, and torque-velocity-curve in extension comes from Raschke et al.
|
|
-# Lumbar-flexion \f$\tau_{ISO}\f$ comes from Beimborn et al.'s observation that the strength ratio of back extensors to flextors at a flextion angle of zero is most often repored as 1.3:1. The torque velocity curve is a guess (slower than back extesors due to the larger moment arm).
|
|
-# Any passive curve that is not accompanied by a curve from the literature (see the plots for details) is an educated guess.
|
|
|
|
|
|
\image html fig_MuscleAddon_Gymnast_HipKneeAnkle.png " Hip/Knee/Ankle: from Jackson and Anderson et al. "
|
|
\image html fig_MuscleAddon_Gymnast_Lumbar.png " Lumbar Extension/Flexion: from Dolan et al.,Raschke et al., and Beimborn et al."
|
|
\image html fig_MuscleAddon_Gymnast_Shoulder3Dof.png " Shoulder 3 DoF torques: from Jackson and Kentel et al. "
|
|
\image html fig_MuscleAddon_Gymnast_ElbowForearm.png " Elbow flexion/extension: from Kentel et al."
|
|
\image html fig_MuscleAddon_Gymnast_Wrist3Dof.png " Wrist 3 DoF torques: from Jackson and Kentel et al."
|
|
|
|
|
|
<b>Parameterized Curves used here vs. Literature</b>
|
|
|
|
The curves used in this implementation are 2nd order 2-dimensional
|
|
Bezier curves. The curves described in Anderson et al., Jackson,
|
|
Kentel were not directly used because they are not continuous to the
|
|
second derivative (a requirement for most gradient based optimization
|
|
routines). There are some other detailed differences that might be
|
|
of interest:
|
|
|
|
-# Anderson et al.'s torque-velocity curve tends to large
|
|
negative values for fast eccentric contractions. This is
|
|
in contrast to the literature which says that at large
|
|
eccentric contractions the torque-velocity curve (or the
|
|
force-velocity-curve) tends to a value between 1.0 and 1.4.
|
|
-# Anderson et al.'s torque-velcity curve for ankle extension
|
|
did not cross the x-axis on the concentric side of the curve.
|
|
This would endow the plantar flexors with super-human abilities.
|
|
This error has been corrected by fitting a Bezier curve to a
|
|
Hill-type curve that passes through the point where
|
|
\f$\dot{\theta}= \frac{1}{2} \dot{\theta}_{MAX}\f$
|
|
-# Anderson et al.'s, Jackson, and Kentel et al. had discintinuities
|
|
in the first derivative of the force velocity curve at
|
|
\f$\dot{\theta}=0\f$. While this follows Huxley's famous observations
|
|
that the slope does discontinuously change at at \f$\dot{\theta}=0\f$.
|
|
This is not a phenomena that is not compatible with most optimal
|
|
control formulations and thus this discontinuity is not present in
|
|
the force velocity curves used in this model.
|
|
-# Anderson et al. and Kentel et al.'s active-torque-angle curves
|
|
can achieve negative values - this is obviously undesirable as it
|
|
will allow a muscle to push.
|
|
-# Kentel et al.'s activation inhibiition function does not always
|
|
cross 1.0 for \f$\dot{\theta}=0\f$, which means that \f$\tau_{ISO}\f$
|
|
is not reached. This makes for a confusing model to use.
|
|
|
|
|
|
<b>Coordinate Mapping</b>
|
|
|
|
Every author chose a particular convention for measuring
|
|
the angles of the hip, knee, ankle joint, shoulder, elbow, wrist and
|
|
lumbar --- see the figure for details. These conventions have all
|
|
been mapped to the one used in the illustrations. You will need to
|
|
use the figure, your model, and the constructors appropriately
|
|
so that
|
|
|
|
-# the joint angle of your model is correctly mapped to the
|
|
fiber angle of the Millard2016TorqueMuscle;
|
|
-# the sign of the muscle's output torque matches the
|
|
sign associated with your model.
|
|
|
|
To map from your model's joint coordinates to the joint coordines
|
|
used in this model (see the figure in the description)
|
|
the followinq equation is used at the torque level
|
|
|
|
\f$ jointTorque = signOfJointTorque*fiberTorque \f$
|
|
|
|
where fiberTorque is the torque produced by Anderson et al.'s curves,
|
|
which is always positive. At the position level, the angles from your
|
|
models joint angle to Anderson et al.'s joint angle (called fiberAngle)
|
|
are mapped using
|
|
|
|
\f$ fiberAngle = signOfJointAngleRelativeToAnderson2007*(jointAngle-jointAngleOffsetRelativeToAnderson2007). \f$
|
|
|
|
Internally the sign of the fiber velocity follows signOfJointTorque so
|
|
that the signs of joint power and muscle power are consistent.
|
|
|
|
<b>Strength Scaling</b>
|
|
|
|
The leg strength (here we mean \f$\tau_{ISO}\f$)
|
|
predicted by Anderson et al.'s curves should be taken
|
|
as a good first approximation. While Anderson et al.'s data set is
|
|
the most comprehensive in the literature, they only measured torques
|
|
from active people: they did not include people at the extremes
|
|
(both very weak, and very strong), nor did they include children.
|
|
Finally, the torques produced by each subject were normalized by
|
|
subjectMassInKg*subjectHeightInM*accelerationDueToGravity. Strength
|
|
is a strange phenomena which is not nicely normalized by just these
|
|
quantites, and so the strength predicted by Anderson et al.'s curves
|
|
might not fit your subject even if they are represented in Anderson
|
|
et al.'s data set.
|
|
|
|
The strength used in the Gymnast data set is fitted to an elite
|
|
male gymnast. It goes without saying that an elite gymnast has
|
|
strength proportions, and an absolute strength that are not typical.
|
|
In the future it would be nice to have a function that could provide
|
|
an educated guess about how to map Gymnast's strengths to that of
|
|
another subject. For the moment I have no idea how to do this, nor
|
|
am I aware of any works in the literature that can provide insight
|
|
of how to do this. For now the whole-body Gymnast model should be
|
|
viewed as being a representation of what is possible for a human,
|
|
but not a typical human. At the present time the default strength
|
|
settings of the Gymnast are not scaled by subject height, nor
|
|
weight.
|
|
|
|
If you happen to know the maximum-isometric-active-torque (note this
|
|
does not include the passive component) that your subject can
|
|
produce,you can update the strength of the torque-muscle using the
|
|
functions getMaximumActiveIsometricTorque(), and
|
|
setMaximumActiveIsometricTorque().
|
|
|
|
<b>Limitations</b>
|
|
|
|
This rigid-tendon torque muscle has some limitations that you should
|
|
be aware of:
|
|
|
|
-# There are no elastic tendons. That means that the mapping between
|
|
the mechanical work done by this torque actuator will greatly differ
|
|
from the positive mechanical work done by a torque actuator that
|
|
includes an elastic tendon. This difference is greatest for those
|
|
muscles with long tendons - namely the Achilles tendon. If you are
|
|
interested in fiber kinematics, fiber work, or metabolic energy
|
|
consumption you cannot use this model especially for muscles that
|
|
have long tendons.
|
|
-# This model formulation predicts torque well, but does a poor job
|
|
of predicting joint stiffness. In this model stiffness is given
|
|
by the partial derivative of torque w.r.t. joint angle. Since the
|
|
active-torque-angle curve fits a cosine function, it is possible
|
|
to construct a torque muscle that has a region of physically
|
|
impossible negative stiffness. Real muscle, in constrast, always
|
|
has a positive stiffness even on the descending limb of the
|
|
active-torque-angle curve (see Rassier et al. for details).
|
|
-# Muscles that cross 2 joints (e.g. the hamstrings) produce coupled
|
|
torques at both of those joints. In this model there is no coupling
|
|
between joints. Furthermore, because of the lack of coupling the
|
|
curves used here are only valid for the posture that Anderson et al.,
|
|
Jackson, and Kentel et al.
|
|
used when they made their data collection. If you are interested
|
|
in simulating postures that are very different from those described
|
|
in by these authors then the results produced by this model should
|
|
be treated as very rough.
|
|
-# Because this is a joint-torque muscle, none of the joint contact
|
|
forces predicted will come close to matching what is produced by
|
|
line-type muscles. If you are interested in joint-contact forces you
|
|
cannot use this model.
|
|
|
|
This simple model is a fast approximate means to constrain the joint
|
|
torque developed in the body to something that is physiologically
|
|
possible. That is it.
|
|
|
|
<b>Units</b>
|
|
Although the figure in this description has angles in units
|
|
of degrees, this is only to help intuitition: when using
|
|
the model, use radians. This model uses MKS:
|
|
|
|
-Distance: m
|
|
-Angles: radians
|
|
-Angular velocity: radians/s
|
|
-Mass: kg
|
|
-Torque: Nm
|
|
-Time: second
|
|
-Power: Nm/second
|
|
|
|
|
|
<b>References</b>
|
|
|
|
-# Anderson, D. E., Madigan, M. L., & Nussbaum, M. A. (2007).
|
|
Maximum voluntary joint torque as a function of joint angle
|
|
and angular velocity: model development and application to
|
|
the lower limb. Journal of biomechanics, 40(14), 3105-3113.
|
|
|
|
-# Beimborn, D. S., & Morrissey, M. C. (1988). A review of the
|
|
literature related to trunk muscle performance. Spine, 13(6), 655-660.
|
|
|
|
|
|
-# Dolan, P., A. F. Mannion, and M. A. Adams. Passive tissues help
|
|
the back muscles to generate extensor moments during lifting.
|
|
Journal of Biomechanics 27, no. 8 (1994): 1077-1085.
|
|
|
|
|
|
-# Jackson, M.I. (2010). The mechanics of the Table Contact
|
|
Phase of Gymnastics Vaulting. Doctoral Thesis, Loughborough
|
|
University.
|
|
|
|
-# Kentel, B.B., King, M.A., & Mitchell, S.R. (2011).
|
|
Evaluation of a subject-specific torque-driven computer simulation
|
|
model of one-handed tennis backhand ground strokes. Journal of
|
|
Applied Biomechanics, 27(4),345-354.
|
|
|
|
-# Millard, M., Uchida, T., Seth, A., & Delp, S. L. (2013).
|
|
Flexing computational muscle: modeling and simulation of
|
|
musculotendon dynamics. Journal of biomechanical engineering,
|
|
135(2), 021005.
|
|
|
|
-# Raschke, U., & Chaffin, D. B. (1996). Support for a linear
|
|
length-tension relation of the torso extensor muscles: an
|
|
investigation of the length and velocity EMG-force relationships.
|
|
Journal of biomechanics, 29(12), 1597-1604.
|
|
|
|
-# Rassier, D. E., Herzog, W., Wakeling, J., & Syme, D. A. (2003).
|
|
Stretch-induced, steady-state force enhancement in single
|
|
skeletal muscle fibers exceeds the isometric force at optimum
|
|
fiber length. Journal of biomechanics, 36(9), 1309-1316.
|
|
|
|
|
|
|
|
*/
|
|
class Millard2016TorqueMuscle {
|
|
|
|
public:
|
|
/**
|
|
Default constructor, which for the moment does nothing.
|
|
Calling any of the models functions after the default
|
|
construction will result in a runtime error.
|
|
*/
|
|
Millard2016TorqueMuscle();
|
|
|
|
|
|
/**
|
|
This constructor allows you to easily access the large
|
|
table of built-in torque muscle coefficients to create
|
|
a torque muscle that best represents the joint of interest.
|
|
|
|
<b> Note: directions </b>
|
|
This constructs a single joint-torque muscle:
|
|
it can only generate torque in one direction. If you want
|
|
to generate a torque in two directions, you need 2 torque
|
|
muscles.
|
|
|
|
<b> Note: signs and offsets </b>
|
|
|
|
All of the angles in these models are defined anatomically.
|
|
You will need to set a series of variables to correctly
|
|
map from your model's joint coordinates and sign conventions
|
|
to that of the models:
|
|
jointAngleOffsetRelativeToDoxygenFigures,
|
|
signOfJointAngleRelativeToDoxygenFigures,
|
|
signOfJointTorqueToDoxygenFigures. Also note that due to
|
|
the anatomical angle definitions some left and right handed
|
|
joints will require different signs. This will be true
|
|
for internal/external rotation at the shoulder,
|
|
horizontal adduction/abduction at the shoulder, ulnar/radial
|
|
deviation at the wrist, pronation/supination of the wrist,
|
|
and others as the list of directions grows.
|
|
|
|
|
|
@param dataSet
|
|
The desired source of joint torque
|
|
coefficients. Use the DataSet structure to choose
|
|
the desired data set (e.g. DataSet::Anderson2007,
|
|
or DataSet::Gymnast)
|
|
|
|
@param subjectInfo
|
|
A struct that contains metadata about the subject
|
|
which is used to scale the maximum torque of the
|
|
torque muscle.
|
|
|
|
@param jointTorque
|
|
Select the joint and torque direction of interest.
|
|
Use the struct for each data set to choose a
|
|
joint-torque-direction that is in the set (e.g.
|
|
Anderson2007::HipExtension, or
|
|
Gymnast::ShoulderHorizontalAdduction)
|
|
|
|
@param jointAngleOffsetRelativeToDoxygenFigures
|
|
Offset angle between your model's joints and the
|
|
reference figures in class description.
|
|
|
|
@param signOfJointAngleRelativeToDoxygenFigures
|
|
The sign convention that converts your model's joint
|
|
angles to the angles used in the reference figures.
|
|
|
|
@param signOfJointTorqueToDoxygenFigures
|
|
The sign that maps fiberTorque from Anderson's model
|
|
(which is always positive) to the correctly signed
|
|
joint torque for your model.
|
|
|
|
@param name
|
|
The name of the muscle. This is needed to do useful
|
|
things like provide error messages that are human
|
|
readable.
|
|
|
|
@throws abort() when
|
|
-# The combination of dataSet, gender, joint, and jointDirection does not correspond to a valid entry
|
|
-# subjectHeightInMeters <= 0
|
|
-# subjectMassInKg <= 0
|
|
-# abs(signOfJointTorque)-1 > epsilon
|
|
|
|
*/
|
|
Millard2016TorqueMuscle(
|
|
DataSet::item dataSet,
|
|
const SubjectInformation &subjectInfo,
|
|
int jointTorque,
|
|
double jointAngleOffsetRelativeToDoxygenFigures,
|
|
double signOfJointAngleRelativeToDoxygenFigures,
|
|
double signOfJointTorqueToDoxygenFigures,
|
|
const std::string& name
|
|
);
|
|
|
|
|
|
/**
|
|
Calculates the joint torque developed by the
|
|
muscle.
|
|
|
|
@param jointAngle (radians)
|
|
|
|
@param jointAngularVelocity (radians/sec)
|
|
|
|
@param activation: the percentage of the muscle that is
|
|
turned on [0-1]. This function allows activations to be
|
|
outside [0,1], because this is useful during the
|
|
intermediate solutions of an optimization run. However,
|
|
you must ensure after the fact that your activations
|
|
fall within a bound of [0,1].
|
|
|
|
@returns torque developed by the musce in (Nm).
|
|
*/
|
|
double calcJointTorque(
|
|
double jointAngle,
|
|
double jointAngularVelocity,
|
|
double activation) const;
|
|
|
|
|
|
/**
|
|
Calculates a large number of internal quantities of the
|
|
torque muscle ranging from the values of the muscle's
|
|
components, the stiffness of the muscle, and its power output.
|
|
|
|
@param jointAngle (radians)
|
|
|
|
@param jointAngularVelocity (radians/sec)
|
|
|
|
@param activation: the percentage of the muscle that is
|
|
turned on [0-1]. This function allows activations to be
|
|
outside [0,1], because this is useful during the
|
|
intermediate solutions of an optimization run. However,
|
|
you must ensure after the fact that your activations
|
|
fall within a bound of [0,1].
|
|
|
|
@param torqueMuscleInfoStruct: A torque muscle struct
|
|
*/
|
|
void calcTorqueMuscleInfo(
|
|
double jointAngle,
|
|
double jointAngularVelocity,
|
|
double activation,
|
|
TorqueMuscleInfo& torqueMuscleInfoStruct) const;
|
|
|
|
/**
|
|
@return the sign of the joint torque (+/- 1)
|
|
*/
|
|
double getJointTorqueSign() const;
|
|
|
|
/**
|
|
@return the sign of the angle sign relative to the
|
|
figures in the class description (+/- 1)
|
|
*/
|
|
double getJointAngleSign() const;
|
|
|
|
/**
|
|
@return the offset angle between the model's joint
|
|
and the figures in the class description (rad)
|
|
*/
|
|
double getJointAngleOffset() const;
|
|
|
|
|
|
/**
|
|
@return the maximum-active-isometric torque that this muscle
|
|
can produce in Nm.
|
|
*/
|
|
double getMaximumActiveIsometricTorque() const;
|
|
|
|
/**
|
|
@return the joint angle at which the normalized
|
|
active-torque-angle curve peaks at its
|
|
maximum value of 1.0. Angle is in radians
|
|
*/
|
|
double getJointAngleAtMaximumActiveIsometricTorque() const;
|
|
|
|
/**
|
|
@return the joint angle at which the normalized
|
|
passive-torque-angle curve reaches a value
|
|
of 1.0. If this curve never reaches a value
|
|
of 1.0 (because it is flat, or the
|
|
passiveTorqueScale has been set to 0) a value
|
|
of std::numeric_limits<double>::signaling_NaN()
|
|
is returned. Use the std function isfinite to
|
|
test if a signaling_NaN has been returned.
|
|
Angle is in radians
|
|
*/
|
|
double getJointAngleAtOneNormalizedPassiveIsometricTorque() const;
|
|
|
|
/**
|
|
@return the maximum concentric joint angular velocity
|
|
in radians.
|
|
*/
|
|
double getMaximumJointAngularVelocity() const;
|
|
|
|
/**
|
|
@return the passive-torque-scale \f$s_P\f$ that is applied
|
|
to the passive-torque-curve.
|
|
*/
|
|
double getPassiveTorqueScale() const;
|
|
|
|
/**
|
|
@return the angle \f$\theta_S\f$ that the passive curve has
|
|
been shifted (radians).
|
|
*/
|
|
double getPassiveCurveAngleOffset() const;
|
|
|
|
/**
|
|
@return The normalized damping term \f$\beta\f$ term
|
|
in the torque muscle model. See class description
|
|
for details.
|
|
*/
|
|
double getNormalizedDampingCoefficient() const;
|
|
|
|
/**
|
|
@param beta -t normalized damping term \f$\beta\f$ term
|
|
in the torque muscle model. See class description
|
|
for details.
|
|
@throw abort() if beta < 0
|
|
*/
|
|
void setNormalizedDampingCoefficient(double beta);
|
|
/**
|
|
Sets the scaling of the passive-joint-torques. By default
|
|
this scale
|
|
is one.
|
|
|
|
@param passiveTorqueScale
|
|
The scale \f$s_P\f$ applied to the
|
|
passive-joint-torque curve (unitless)
|
|
*/
|
|
void setPassiveTorqueScale(double passiveTorqueScale);
|
|
|
|
/**
|
|
@param passiveCurveAngleOffsetVal the angle \f$\theta_S\f$
|
|
that the passive curve should be shifted. Angles in radians
|
|
*/
|
|
void setPassiveCurveAngleOffset(
|
|
double passiveCurveAngleOffsetVal);
|
|
|
|
|
|
/**
|
|
This function iteratively solves for the passiveTorqueScale
|
|
so that at the specified jointAngle the passive curve
|
|
develops the specified passiveTorque
|
|
|
|
@param jointAngle the target joint angle in radians
|
|
@param passiveTorque the target passive joint torque in Nm.
|
|
@throws abort if jointAngle is not in the domain of the curve
|
|
@throws abort if passiveTorque < sqrt(eps)
|
|
*/
|
|
void fitPassiveTorqueScale(double jointAngle,
|
|
double passiveTorque);
|
|
|
|
/**
|
|
This function solves for the passive curve angle offset
|
|
so that at the specified jointAngle the passive curve
|
|
develops the specified passiveTorque
|
|
|
|
@param jointAngle the target joint angle in radians
|
|
@param passiveTorque the target passive joint torque in Nm.
|
|
@throws abort if passiveTorque < sqrt(eps)
|
|
*/
|
|
void fitPassiveCurveAngleOffset(double jointAngle,
|
|
double passiveTorque);
|
|
|
|
/**
|
|
Sets the strength of the muscle to match a desired value.
|
|
|
|
@param maxIsometricTorque
|
|
The desired maximum-active-isometric torque of the
|
|
muscle (Nm)
|
|
|
|
*/
|
|
void setMaximumActiveIsometricTorque(
|
|
double maxIsometricTorque);
|
|
|
|
/**
|
|
@return the SmoothSegmentedFunction the has been fitted to
|
|
Anderson et al.'s passive torque angle curve.
|
|
*/
|
|
const RigidBodyDynamics::Addons::Geometry::
|
|
SmoothSegmentedFunction& getActiveTorqueAngleCurve() const;
|
|
|
|
/**
|
|
@return the SmoothSegmentedFunction the has been fitted to
|
|
Anderson et al.'s active torque angle curve.
|
|
*/
|
|
const RigidBodyDynamics::Addons::Geometry::
|
|
SmoothSegmentedFunction& getPassiveTorqueAngleCurve() const;
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/**
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@return the SmoothSegmentedFunction the has been fitted to
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Anderson et al.'s torque velocity curve.
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*/
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const RigidBodyDynamics::Addons::Geometry::
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SmoothSegmentedFunction& getTorqueAngularVelocityCurve() const;
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/**
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Prints 2 csv files:
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-# 'fileName' + '_variableLengthfixedVelocity': All of the
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fields in TorqueMuscleInfo are recorded to file as the
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jointAngle varies but the jointAngularVelocity is zero.
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-#'fileName' + '_fixedLengthVariableVelocity': All of the fields
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in TorqueMuscleInfo are recorded to file as the jointAngle is
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fixed but the jointAngularVelocity varies.
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Each column has a header, so that you can tell what each
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piece of data means.
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@param path: the path to the destination folder. Don't put
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an '\' on the end.
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@param fileNameWithoutExtension: the name of the file, but
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without an extension.
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@param numberOfSamplePoints: the number of sample points to
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use in the files.
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*/
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void printJointTorqueProfileToFile(
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const std::string& path,
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const std::string& fileNameWithoutExtension,
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int numberOfSamplePoints);
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std::string getName();
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void setName(std::string& name);
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private:
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/**
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@return the parameters c1,...,c6 that desribe the
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active-torque-angle and torque-velocity curves of this
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torque muscle model. See the Anderson et al. paper metioned
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in the class description for detail.
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*/
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//const RigidBodyDynamics::Math::VectorNd&
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//getParametersC1C2C3C4C5C6();
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/**
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@return the parameters b1,k1,b2,k2 that desribe the
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passive-torque-angle curves of this model. See the Anderson
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et al. paper metioned in the class description for detail.
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*/
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//const RigidBodyDynamics::Math::VectorNd&
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//getParametersB1K1B2K2();
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bool muscleCurvesAreDirty;
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void updateTorqueMuscleCurves();
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TorqueMuscleInfo tmInfo;
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RigidBodyDynamics::Addons::Geometry::
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SmoothSegmentedFunction taCurve;
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RigidBodyDynamics::Addons::Geometry::
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SmoothSegmentedFunction tpCurve;
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RigidBodyDynamics::Addons::Geometry::
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SmoothSegmentedFunction tvCurve;
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RigidBodyDynamics::Math::VectorNd c1c2c3c4c5c6Anderson2007;
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RigidBodyDynamics::Math::VectorNd b1k1b2k2Anderson2007;
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RigidBodyDynamics::Math::VectorNd gymnastParams;
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DataSet::item dataSet;
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double maxActiveIsometricTorque;
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double angleAtOneNormActiveTorque;
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double omegaMax;
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double angleAtOneNormPassiveTorque;
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double passiveTorqueScale;
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double passiveCurveAngleOffset;
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double beta; //passive damping coefficient
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double subjectHeightInMeters;
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double subjectMassInKg;
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double scaleFactorAnderson2007;
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double signOfJointAngle;
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double signOfConcentricAnglularVelocity;
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double signOfJointTorque;
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double angleOffset;
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std::string muscleName;
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double calcJointAngle(double fiberAngle) const;
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double calcFiberAngle(double jointAngle) const;
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double calcFiberAngularVelocity(
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double jointAngularVelocity) const;
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//const static RigidBodyDynamics::Math::MatrixNd&
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//getAnderson2007ParameterMatrix();
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static double const Anderson2007Table3Mean[36][14];
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static double const Anderson2007Table3Std[36][14];
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static double const GymnastWholeBody[22][12];
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};
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}
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}
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}
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#endif
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