SIMM–Matlab Interface
Contents
1. For each external point force there will be six inputs labeled Segment name pointfrec px Force number Segment name pointfre py Force number Segment name pointfre px Force number Segment name pointfrc vx Force number Segment name pointfre vy Force number Segment name pointfre vz Force number You need to supply the point of application of the force in local reference frame of the segment to the first three inputs and the force vector in global reference frame to the last three inputs Inputs to the external body torques For each external body torque there will be three inputs labeled Segment name bodytorque vx Torque number Segment name bodytorque vy Torque number Segment name bodytorque vz Torque number You need to supply the torque vector in global reference to these inputs Inputs to the external hinge torques For each external hinge torque there will be one input labeled Joint axis name hingetorque Torque number You need to feed this input with the hinge torque value The direction of the torque will be that of the joint axis 15 6 2 Outputs of the Simulink model Outputs for states This output port outputs the position velocity and acceleration of all the degrees of freedom in the system Each output is clearly labeled and can be identified easily You can connect these outputs to monitor the model outputs use them as inputs to your feedback controllers etc Y2. 16 QUIPUSTOFSCASO ni een ea 16 Outputs for storage and animation i 17 6 3 PARAMETERS OF THE SIMULINK MODEL 18 6 4 RUNNING A SIMULATION AND VIEWING THE RESULTS 21 7 A simple model of arm an example rnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 22 Todo MODELDESCRIP TION na aaa asta ine ess 23 EL SKELETAEMODEL rali 24 Teds MUSCLE MODEL NS 26 7 4 CONVERTING SIMM MODEL TO SIMULINK MODEL 29 7 5 SETTING UP AND RUNNING SIMULATION 32 7 6 VIEWING THE RESULTS OF SIMULATION IN SIMM 35 8 MMS License Agreement rrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnns 36 1 Introduction Simulink Mathworks Inc USA is a popular software for modeling simulating and analyzing dynamical systems It has many built in blocks and can take advantage of the toolboxes in Matlab However it has no utility for development of musculoskeletal models On the other hand SIMM Musculographics Inc USA is a popular software for development of sophisticated musculoskeletal models To perform forward dynamic simulations with SIMM however the user must write additional C programs to model the muscle activation controllers feedback sensors optimization algorithms etc that is both time consuming and difficult for non programmers Musculoskeletal Modeling in Simulink MMS is software that c
3. dynamic files Y N Y Explanation Answer is yes default because you should have run SIMM to generate simulation files in the model directory before running MMS gt gt Add prescribed joints Y N N Explanation Answer is no because we have only one degree of freedom and we don t want to prescribe it gt gt Add external point force Y N N y Explanation Answer is yes to apply external point forces gt gt How many point force on r_ulna 0 1 Explanation Answer is 1 to apply 1 external point force on r_ulna The point of application in local frame and the force vector in global frame will be provided in runtime 29 gt gt Add body torque Y N N Explanation Answer is no default to not apply any body torque gt gt Add hinge torque Y N N Explanation Answer is no default to not apply any hinge torque gt gt Add sensors Y N N y Explanation Answer is yes to attach sensors 1 Global position of a point on a segment 2 Global velocity of a point on a segment 3 Global acceleration of a point on a segment 4 Accelerometer aligned with segment axes 5 Gyroscope aligned with segment axes 6 Inclination with respect to vertical gravity vector 7 Global position of a point along a muscles line of action 8 Muscle spindle Select type of sensor 4 Explanation Answer is 4 to attach an accelerometer 0 r_ulna Select a segment to attach the senso
4. feline fiber types e Recruitment type 1 selects Natural recruitment and recruitment type 2 selects Intramuscular FES recruitment An example of an input muscle file can be found in chapter 6 8 4 3 External forces and torques External forces and torques are defined in a kinetics file and must be prepared following the SIMM s guidelines In SIMM s kinetics file you record the forces and torques you want to apply in each frame The number of frames time step between the frames and therefore the total time is fixed Any change requires the modification of the kinetics file and cannot be done in runtime So you cannot change the external forces according to a runtime event or state variables The forces and torques are all in local reference frame of the segments In most applications it is easier to provide the external forces in global reference frame such as the data from a force plat In MMS you can still use the kinetics file to apply external force and torques if you are comfortable preparing these files or do not want the flexibility of changing them in runtime or when you want to apply the external forces and torques that are expresses in local frames of the segments However with MMS you can now apply your external forces from within Simulink This could be in addition to the external forces applied in the kinetics file or the only forces applied to the system In this case the external forces and torques are exp
5. files to a MMS directory e g CAMMS This is a safe place to store the original MMS files You will need to copy all of these files to your model directory whenever you create a new model To use MMS copy all the files in C MMS to your model directory For example if you have a SIMM model of arm located in C mymodels Arm jnt copy all the MMS files to C mymodels Keep the original copy in C MMS for later use with other models 4 Building Forward Dynamic Models in SIMM 4 1 Skeletal model The topology of the skeletal model including the segments joints degrees of freedom and the physical properties of the segments are defined in the joint file You must follow the guidelines in SIMM s user manual to write the joint file With MMS some model features can be implemented differently that are discussed below In SIMM you can define the joint s axis to be free or constrained The constrained joints can be fixed or forced to follow a trajectory However once defined the constraints cannot be modified in runtime without regenerating and compiling the dynamic files In MMS however you can define all joint axis in the joint file to be free Later when you build the simulink model you can constrain any joint axis you want This time the joint constraints trajectories will be provided from within Simulink and can be modified in runtime without rebuilding the model This provides greater flexibility in application of the constrained
6. the MMS and user added blocks however will be disconnected and you may need to reconnect them manually The next chapter explains how the created simulink model can be used to perform forward dynamic simulations 12 6 Forward dynamic simulations in Simulink Here you will learn how to use the simulink model created by the MMS to perform forward dynamic simulations The MMS builds a simulink model that has a number of inputs and outputs that depend on the joint file and your answers to the questions in the interactive model building process It has also some adjustable parameters that you can modify For an example see chapter 6 If you double click on the simulink block to open its subsystem you will find that all of the inputs and outputs are properly labeled and are all familiar names because they are extracted from your own joint file So you will know what to feed to the inputs and how to use the outputs However in the following I will briefly discuss the inputs outputs and their use 13 6 1 Inputs to the Simulink model Inputs to the muscles For SIMM muscle models you will have inputs labeled Muscle name _act This input needs to be provided with muscle activation 0 1 For Non SIMM User Defined muscle models you will have inputs labeled Muscle name _act_frc_nfl_nfv This input needs to be fed with activation force normalized fiber length and normalized fiber velocity You can use Simulink s library bl
7. was generated in the last section looks like the following It has all the necessary inputs and outputs with appropriate labels r_elbow_flexion Elb_Flex_act r_elbow_flexion_vel P Elb_Ext_Long_act_frc_nfl_nfv r_elbow_flexion_acc p Elb Ext Short act mil Eldre ae Outs Elb Ext Long act out r ulna pointfrc px 0 Elb Ext Short act out p r ulna pointfrc py 0 Elb Flex frc out Elb Ext Long frc out p Elb Ext Short frc out Elb Flex len p r ulna pointfrc vy 0 Elb Ext Long len p Elb Ext Short len p r ulna accelerometer 1P r ulna pointfrc pz 0 r ulna pointfrc vx 0 r ulna pointfrc vz 0 Elb Ext Short spindle 2 dyn static fusimotor inputs Elb Ext Short spindle 2 prim sec outputs b Dynamic Model 32 Double clicking on the Simulink block reveals its subsystem as follows 33 As an example of how an MMS model may be connected to other blocks we make the following connections to prepare the model for simulation e Elb Flex actis a default SIMM muscle as indicated in input muscle file and needs only activation as its input which is connected to a constant input of 0 1 e Elb Ext Long is a Non SIMM User Defined muscle and needs four inputs These inputs must come from a muscle model developed by the user Because we don t have one here we provide arbitrary values of 1 as activation 100 N as muscle force and 0 for fiber length and velocity e Elb Ext Short is a Non SIMM Virtual Muscle and need two inputs activati
8. 0 000000 0 000000 axis2 0 000000 1 000000 0 000000 axis3 0 000000 0 000000 1 000000 tx constant 0 014371 ty constant 0 275795 tz constant 0 038900 r1 constant 0 000000 r2 constant 0 000000 r3 function f4 r_elbow_flexion endjoint a hi GENCOORDS a a 24 begingencoord r_elbow_flexion range 0 00000 150 000000 keys e_key default_value 0 000000 minrestraint f5 maxrestraint f5 endgencoord a FUNCTIONS feb O OE RIO EE LEE beginfunction f4 360 000000 360 000000 360 000000 360 000000 endfunction beginfunction f5 0 000000 0 000000 10 000000 25 000000 20 000000 50 000000 30 000000 100 000000 endfunction a MUSCLE WRAP OBJECTS Free NOR NO ONE Je beginwrapobject elbowextwrap wraptype cylinder segment r humerus translation 0 0000 0 2760 0 0440 radius 0 0300 height 0 0400 quadrant x endwrapobject beginwrapobject elbowflxwrap wraptype cylinder segment r humerus translation 0 0000 0 2760 0 0440 radius 0 0300 height 0 0400 quadrant x endwrapobject 25 7 3 Muscle model The three muscle models are defined in the following muscle file Elbow flexor uses SIMM muscle model number 1 while elbow extensor is a Non SIMM muscle model MUSCLE FILE FOR ARM MODEL PARAMETER NAMES FOR Non SIMM Virtual Muscles begindynamicparameters mass optimal_tendon_length max_musculotendon_length act level when all MU re
9. 000 endtendonforcelengthcurve beginforcevelocitycurve 10 000000 0 000000 1 000000 0 000000 0 600000 0 080000 0 300000 0 233333 0 100000 0 540000 0 000000 1 000000 0 100000 1 391489 0 300000 1 593548 0 600000 1 681481 0 800000 1 707692 1 000000 1 724409 10 000000 1 724409 endforcevelocitycurve endmuscle DEFINE ELBOW FLEXOR AS MUSCLE MODEL 7 MODEL 7 DEFINES A SIMM MUSCLE MODEL beginmuscle Elb_Flex beginpoints 0 01000 0 14000 0 02200 segment r_humerus 0 00200 0 05000 0 02100 segment r_ulna endpoints max_force 100 0 optimal_fiber_length 0 10 tendon_slack_length 0 06 pennation_angle 0 0 max_contraction_velocity 5 00000 wrapobject elbowflxwrap muscle_model 7 endmuscle DEFINE ELBOW EXTENSOR AS MUSCLE MODEL 9 MODEL 9 DEFINES NON SIMM User Defined MUSCLE MODEL beginmuscle Elb_Ext_Long beginpoints 0 00503 0 06190 0 01169 segment r_humerus 0 03000 0 05000 0 02200 segment r_ulna endpoints wrapobject elbowextwrap muscle_model 9 endmuscle 21 DEFINE ELBOW EXTENSOR 2 AS MUSCLE MODEL 10 MODEL 10 DEFINES NON SIMM Virtual Muscle MODEL beginmuscle Elb_Ext_Short beginpoints 0 00255 0 14472 0 01831 segment r_humerus 0 03000 0 05000 0 02200 segment r_ulna endpoints wrapobject elbowextwrap muscle_model 10 optimal_fiber_length 0 1400 mass 0 057890 optimal_tendon_length 0 100000 max_musculotendon
10. 2 you will find the list of changes and new features in this version of MMS In chapter 2 you will find the system requirements and installation procedure for the use of MMS Chapter 3 explains the procedure for building a forward dynamic model in SIMM Because this is covered in SIMM s documentation I will only explain those aspects that relate to the use of MMS Chapter 4 explains the use of MMS to build Simulink models from the SIMM models In chapter 5 you will learn how to setup and run the simulink model of your musculoskeletal system Finally chapter 6 uses an example to go through the complete process of building a forward dynamic model and performing simulations 2 New in this version The main changes in this version of MMS are as follows A new feature allows the user to attach sensors to the segments or muscles Sensors of up to 100 can be chosen from eight different artificial and natural sensor types and attached to any point on the segment or muscle In older version of MMS the user could change the model s initial condition in the final Simulink block s parameter list This feature is now removed because the new version of SIMM 3 2 allows the user to change these initial values in forparams txt file Initial installation of MMS is now easier because there is no need to manually change some of the SIMM files for compatibility The MMS models can now be run with or without muscles If you don t provi
11. User s Guide To MMS Musculoskeletal Modeling In Simulink By Rahman Davoodi Medical Device Development Facility Alfred E Mann Institute for Biomedical Engineering University of Southern California http ami usc edu August 2002 Table of Contents 1 INroduciione O o chcca vice aencetes abecanvs chncaees ahacanas auacasasahesaees ahecasssezctateee 3 2 New IN this version as 5 3 System requirements and installation nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 6 3 1 SYSTEM REQUIREMENTS ANS 6 32 NANA 6 4 Building Forward Dynamic Models in SIMM rrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenn 7 4 1 RECETA MODEL see O 7 4 2 MUSCLE MODEM LA aiar een 7 4 3 EXTERNAL FORCES AND TORQUES sognene aliena 9 5 Using MMS to build Simulink models from SIMM model 10 6 Forward dynamic simulations in Simulink snnnnnnnnnnnnnnnnnnnnnnnnnnnnnnvnennen 13 6 1 INPUTS TO THESIMUINKMODEL a act Gees hia ces eats 14 Inputs TO NE INUSCIOS a artes daa hai 14 Inputs to the prescribed joint AXES ooooooocoonncconncoconaconanonancnnnccnnonnnnconanornnnonos 14 Inputs to the external point forces ii 15 Inputs to the external body torques ii 15 Inputs to the external hinge torques i 15 6 2 OUTPUTS OF THE SIMULINK MODEL 00 sseccssscssscsecrossecssstcessssenscsnecosseessees 16 DUDES TO ESS 16 QUIPUISTOFMUSCIOS iras
12. _length 0 2800000 act_level_when_all_MU_recruited 0 800000 fiber_type_database 1 recruitment_type 1 fractional_pcsa_SS 0 2 fractional_pcsa_S 0 3 fractional_pcsa_F 0 5 number_motor_units_SS 4 number_motor_units_S 6 number_motor_units_F 10 endmuscle 28 7 4 Converting SIMM model to Simulink model With the joint and muscle files ready you can now build the Simulink model for forward simulation First you need to load joint and muscle files to the SIMM window and select Save Dynamics from the File menu to generate the files for forward dynamic simulation Select the model folder as the simulation folder and check all three boxes for forward simulation This generates files for forward dynamic simulation in a subdirectory called forward See SIMM user manual for more detail Next you should copy MMS files to the model directory if you haven t done so Open Matlab in the model directory where the model files and the MMS files reside and run MMS MMS model builder guides you through the complete process of configuring and building the simulink model Model builder asks a series of questions to interactively configure the model The questions and answers are given below with their meaning explained gt gt MMS Explanation Runs the MMS script in Matlab gt gt Have you changed any of SIMM model files Y N N y Explanation Answer is yes because this is a new model gt gt Have you run SIMM to generate new
13. cruited fiber type database recruitment type fractional pcsa SS fractional pcsa S fractional pcsa F number motor units SS number motor units S number motor units F enddynamicparameters DEFAULT MUSCLE beginmuscle defaultmuscle beginactiveforcelengthcurve 5 000000 0 000000 0 000000 0 000000 0 401000 0 000000 0 402000 0 000000 0 403500 0 000000 0 527250 0 226667 0 628750 0 636667 0 718750 0 856667 0 861250 0 950000 1 045000 0 993333 1 217500 0 770000 1 438750 0 246667 1 618750 0 000000 1 620000 0 000000 1 621000 0 000000 2 200000 0 000000 5 000000 0 000000 endactiveforcelengthcurve beginpassiveforcelengthcurve 5 000000 0 000000 0 998000 0 000000 0 999000 0 000000 1 000000 0 000000 1 100000 0 035000 1 200000 0 120000 1 300000 0 260000 1 400000 0 550000 1 500000 1 170000 1 600000 2 000000 1 601000 2 000000 1 602000 2 000000 5 000000 2 000000 Rn 26 endpassiveforcelengthcurve begintendonforcelengthcurve 10 000000 0 000000 0 002000 0 000000 0 001000 0 000000 0 000000 0 000000 0 001310 0 010800 0 002810 0 025700 0 004310 0 043500 0 005810 0 065200 0 007310 0 091500 0 008810 0 123000 0 010300 0 161000 0 011800 0 208000 0 012300 0 227000 9 200000 345 000000 9 201000 345 000000 9 202000 345 000000 20 000000 345 000
14. de the muscle file the muscle related inputs and outputs will not appear in final Simulink model Such models can be driven by torque motors external forces and influence of gravity In older version of MMS the users of Virtual Muscle models had to design them separately and add them to the final Simulink model generated by MMS This version of MMS has integrated the Virtual Muscle software allowing the user to define the Virtual Muscle parameters inside the SIMM muscle definition file When creating the final Simulink model you are now given a chance to rebuild an existing model or replace it Rebuilding preserves all the Simulink blocks you may have added to the MMS model This version of MMS is compatible with SIMM 3 2 and Matlab R12 R13 3 System requirements and installation 3 1 System requirements The following software packages are required for building Simulink models of the musculoskeletal systems Windows NT 98 2000 SIMM 3 2 Musculographics Inc USA Dynamics Pipeline 2 0 Musculographics Inc USA SD FAST B 2 Symbolic Dynamics Inc USA Matlab 6 0 or higher with Simulink MathWorks Inc USA Microsoft Visual C 6 0 Microsoft Corporation USA 3 2 Installation To use MMS the software listed in section 3 1 must be installed properly Except for Matlab and Simulink the rest of the software in the list are necessary for running forward dynamic simulations with SIMM Dynamics Pipeline To install MMS Unzip MMS
15. ftware under development pending completion of its development and a decision about its proper dissemination and or commercialization If you use the Musculoskeletal Modeling in Simulink MMS software you agree to be bound by the terms and conditions of this agreement and this will be a legally binding agreement between you and Alfred E Mann Institute AMI hereby grants to you a personal non transferable and non exclusive copy of MMS free of charge to possess duplicate use and execute solely under the terms of this agreement You may not sublicense distribute hypothecate lease loan or otherwise convey the MMS or any portion thereof to anyone and under no circumstance may you use or allow the use of MMS in any manner other than as expressly set forth above You agree that you will not reverse assemble decompile or disassemble or otherwise reverse engineer any portion of the MMS You agree and acknowledge that AMI transfers no ownership interest in the MMS in the intellectual property to you under this Agreement AMI makes no warranties expressed or implied and neither AMI nor any individuals or entities associated with it shall be liable under any circumstances for any special consequential exemplary or punitive damages occurring out of or in connection with the use or performance of the materials covered herein E agree with the terms and conditions of this agreement Signature Date Please mail the c
16. g Where NB is the number of body torques BI Blnr are the indices to the segments where the body torques 1 NB apply When there are no body torques BodyTorque 0 6 HingeTorque NH HI Hlyg Where NH is the number of hinge torques HI HInu are the indices to the joint axes where the hinge torquel NH apply When there are no hinge torques HingeTorque 0 7 Options RUN NSF FDT TOL BUM Where RUN is the run option and must always be 0 NSF is equal to 6 times the number of forces plus 3 times the number of torques in the SIMM s kinetic file FDT is the sample time between the frames of external force data in the SIMM s kinetic file 19 TOL is the tolerance used in assembling the system Modify if assembly of the system fails BUM is the baumgarte constant for constraint stabilization See SD FAST manual for further details 8 Sensors NS NSO ST SS SM SP NS ST NS SS vs SM2ns SP2Ns Where NS is the number of sensors When NS 0 none of the following parameters will exist NSO is the total number of sensory outputs ST STns are the types of sensors 1 NS SS SSns are the segments where the sensors 1 NS are attached will be 0 if not used for the sensor type SM SMys are the muscles where the sensors 1 NS are attached will be 0 if not used for the sensor type SP SPns are positions vectors of length 3 of the sensors on the segment or the muscle If the sensor attach
17. motions An example of a joint file can be found in chapter 6 4 2 Muscle model The muscle geometry insertion points line of action and force production models are all defined in muscle file SIMM allows the user to choose one of their five muscle models or program a new muscle model in C language The latter may be difficult for some and not justified for those who already have a working muscle model in Simulink The MMS however provides the user with two more options for development of Non SIMM muscle models in Simulink User defined muscle models and Virtual Muscle models The procedure for development of these muscle models are explained below SIMM muscle models These are default muscle models that are shipped with SIMM and must be defined according to the guidelines in SIMM s user manual Non SIMM User Defined For Non SIMM User Defined muscle models you still have to follow SIMM s guidelines but You only need to provide the parameters that are related to the musculoskeletal geometry such as the attachement points and wrapping objects and the muscle model number that must be 9 You need to develop your own muscle model inside Simulink This model can use the musculotendon length provided by MMS and other information such as the muscle excitation as inputs and must output four variables including muscle excitation muscle force normalized fiber length and normalized fiver velocity to the MMS Non SIMM Virtual Muscle For N
18. n t have external body torques If you answer yes you will be presented with the names of the segments in the model where you can choose the number of body torques to apply to or skip Next you will be asked gt gt Add hinge torque Y N N Answer no if you don t have external hinge torques If you answer yes you will be presented with the names of the joint axes in the model where you can choose the number of hinge torques to apply to or skip gt gt Add sensors Y N N Answer no if you don t have any sensors If you answer yes you will be presented with the types of sensors and segments or muscles to attach them to You can add as many as 100 sensors Currently there are eight sensor models including both artificial and natural sensors Finally you will be asked 11 gt gt Enter output simulink model name to build Here you have to enter a name for the simulink model to be built If there are no Simulink model with similar name a new model will be created However if a model with similar name is already open or saved to the current directory you will be asked whether you want to rebuild or recreat If you answer recreate the existing model will be replaced with a new model All the user added blocks you may have added to the MMS generated Simulink block will be lost If you answer rebuild default the existing model will be rebuilt while keeping the user added Simulink blocks intact The connection between
19. nge few of the parameters that are shown in bold in the following S function name is the name of the dll file for forward simulation S function parameters contain 8 comma separated parameter vectors These parameter vectors from left to right are defined below 1 General Coordinates NO Where NQ is the number of degrees of freedom NQ must always be greater than zero otherwise the simulation will stop and error will be reported 2 Muscles NM NSM NNSM NS1 NS2 MN MN yu Where NM is the number of muscles in the system NSM is the number of SIMM muscle models NNSM is the number of Non SIMM muscle models NSI is the total number of states for SIMM muscle models NS2 is the total number of states returned by SIMM for all the muscles 18 MN MN ww are the muscle model numbers for muscles 1 NM Muscle model numbers here are those specified in muscle file minus one because the counting starts from 0 When there are no muscles Muscles 0 3 Prescribed Motion NP PI PInp Where NP is the number of prescribed joint axes PIL PIxp are the indices to the prescribed degrees of freedom 1 NP When there are no prescribed joint axes PrescribedMotion 0 4 Point Force NF Fl FIxr Where NF is the number of point forces FI Flyr are the indices to the segments where the point forces 1 NF apply When there are no point forces PointForce 0 5 Body Torque NB BI BIn
20. nged Next you will be asked gt gt Add prescribed joints Y N N Here you can constraint the motion of any joint axis by prescribing its motion The default answer is no N which means you don t have prescribed joints If you answer yes Y you will be presented with the names of the joint axes that are unconstrained free and you can choose to prescribe them or leave them unconstrained For example you may be asked gt gt Prescribe r elbow flexion Y N N Answering yes prescribes r elbow flexion and answering no default leaves it unconstrained 10 If you have constrained the motion of a joint axis in the joint file it won t be available to be prescribed at this stage you can t prescribe a joint axis twice Only the joint axes that are defined as unconstrained in joint file will be available to be prescribed Next you will be asked gt gt Add external point force Y N N Answering no default means that you don t want to apply point forces If you answer yes you will be presented with the names of the segments all the segments except for ground where you can choose to apply external point forces or skip For example you may be asked gt gt How many point force on r_ulna 0 You can enter the number of point forces to be applied to r ulna or Enter for no point forces default Next you will be asked gt gt Add body torque Y N N Answer no if you do
21. ock Mux to combine the four signals into one vector of width four before connection them to the input In case you are confused the activation signal is not really used in any computation It is directly transferred to the output ports for storage and presentation Force signal is the output of your Non SIMM muscle model that is applied to the appropriate points in the skeletal model Normalized fiber length and velocity normalized to fiber optimal length will be used only if you attach a muscle spindle sensor to the muscle If you don t want to attach muscle spindle to a Non SIMM User Defined muscle you can feed these inputs with zero For Non SIMM Virtual Muscle models you will have inputs labeled Muscle name _act_mtl This input must be fed with activation 0 1 and musculotendon length You can use Simulink s library block Mux to combine the two signals into one vector of width two before connection them to the input The musculotendon length for all of the muscles are provided by the MMS Simulink block and can be connected to the input of the Virtual Muscle models Inputs to the prescribed joint axes For each prescribed joint axis there will be three inputs labeled 14 Joint axis name _pos Joint axis name _vel Joint axis name _acc You need to feed these inputs with a compatible set of position velocity and acceleration you want to be prescribed to the joint axis Inputs to the external point forces
22. ombines the capabilities of SIMM and simulink to interactively design simulink models of the musculoskeletal systems MMS facilitates the model development process by Making the final model available in Simulink where many other utilities are available for data analysis presentation control and optimization Eliminating the need for writing any user C code by automatically generating the necessary code Eliminating restrictions on SIMM model properties such as muscle excitations external forces and prescribed motions in SIMM and introducing more flexibility while making the model development easier Adding a feature to make it possible to add sensors to segments and muscles Adding more flexibility in muscle modeling to allow the users to use their own muscle models in addition or in place of the muscle models in SIMM Completely integrating the Virtual Muscle software that allows the user to use Virtual Muscle models in combination or in place of the SIMM default muscle models Keeping 100 compatibility with SIMM so that the older models developed for SIMM can easily be converted to Simulink models In the tradition of not inventing the wheel we have tried to use the best musculoskeletal modeling software that is currently available and combined it with the most popular dynamic simulation software Therefore MMS is a utility that helps to seamlessly integrate these two modeling tools and also adds some very useful features In chapter
23. ompleted form to Rahman Davoodi 1042 West 36 Place Room B12 University of Southern California Los Angeles CA 90089 1112 OR fax it to 213 821 1120 36
24. on SIMM Virtual Muscle you still have to follow SIMM s guidelines but 1 You need to add the following to the top of your muscle file to define additional parameters that are required by Virtual Muscle models begindynamicparameters mass optimal tendon length max musculotendon length act level when all MU recruited fiber type database recruitment type fractional pcsa SS fractional pcsa S fractional pcsa F number motor units SS number motor units S number motor units F enddynamicparameters 2 You need to provide the values of the above parameters in the definition of Virtual Muscle models You also need to provide optimal fiber length and geometric parameters such as attachement points and wrapping objects Finally you need to use muscle model number 10 to select Virtual Muscles 3 The Virtual Muscle parameters are those needed by the Virtual Muscles Buildmuscles utility Selection of these parameters must follow the guidelines of the Virtual Muscle user manual and the following e Currently you can use SS S and F fiber types in human fiber types or feline fiber types to build your muscles You can use Buildfibertypes utility to change the parameters of these fiber types but you cannot add fiber types with new names e Unlike the Virtual Muscle the parameters are given in metric system such as meters and kg e Fiber type database 1 selects human fiber types and fiber types database 2 selects
25. on and musculotendon length Activation input is connected to a constant source of 0 5 The musculutendon input comes from the output of the MMS block e Connect px py and pz of the external force on r ulna to 0 0 1 and 0 meaning that the force will be applied to the hand Connect the vx vy and vz components to 0 10 and 0 meaning that an external force of 10 N will be applied in the direction of Y of the global reference frame downward direction as if an object weighing about 1 kg is carried by the hand e Connect the output ports to the Scopes to view their time course during the simulation The resulting system will look like the following which can be simulated by selecting Start from Simulink s Simulation menu Muscles Activation Muscles Force LO Muscles Length imotor inputs Dynamic Model Spindle Output 34 7 6 Viewing the results of simulation in SIMM Once the simulation run is complete run the Matlab2SIMM script in Matlab by typing gt gt Matlab2SIMM When asked choose the name of the motion file to create Then open the model and motion file in SIMM and view the animation of the simulated movement 35 8 MMS License Agreement Alfred E Mann Institute AMI at the University of Southern California This agreement is being entered into to permit exchange of proprietary information for the pursuit of scientific research and training It is intended to protect so
26. ou may see output ports labeled fixed0 fixedl which you did not expect to see These are in fact fixed or weld joints that SIMM has created based on your joint file To implement these fixed joints SIMM defines a pin joint and then prescribes its motion to force it to stay in its initial position You can monitor the output ports for fixed joints to verify that these fixed joints don t mode in reality Outputs for muscles For each muscle SIMM or Non SIMM the excitation force and length are provided in the output with appropriate labels All these outputs can be used for monitoring the system but musculotendon length will certainly be needed if you have Non SIMM Virtual Muscle models In this case you can connect the appropriate output for the muscle length to your Non SIMM Virtual Muscle models inputs Outputs for sensors The outputs of the sensors depend on the type of sensor Position velocity and acceleration sensors output the XYZ components of the position velocity and acceleration of a point on a segment or a muscle expressed in the global reference frame Accelerometer simulates a 3 axis accelerometer attached to a segment and aligned with its local coordinate frame Therefore it outputs the XYZ components of the acceleration of the attachment point expressed in the segments local reference frame Gyroscope simulates a 3 axis gyroscope attached to a segment and aligned with its local coordinate frame Therefore i
27. r to 0 Explanation Answer is 0 to attach the sensor to r_ulna Enter position of sensor in segment local frame 0 0 0 Explanation Answer is 0 0 0 to attach the accelerometer to the center of r_ulna s local reference frame Add another sensor Y N N y Explanation Answer is yes to attach another sensor 1 Global position of a point on a segment 2 Global velocity of a point on a segment 3 Global acceleration of a point on a segment 4 Accelerometer aligned with segment axes 5 Gyroscope aligned with segment axes 6 Inclination with respect to vertical gravity vector 7 Global position of a point along a muscles line of action 8 Muscle spindle Select type of sensor 8 Explanation Answer is 8 to attach a muscle spindle sensor 30 0 Elb_Flex 1 EIb Ext Long 2 Elb_Ext_Short Select the muscle to attach the sensor to 0 2 Explanation Answer is 2 to attach a muscle spindle to Elb_Ext Short Add another sensor Y N N Explanation Answer is no to not attach any more sensors gt gt Enter output simulink model name to build arm Explanation Answer is arm to name the simulink model as arm mdl The arm mdl is the simulink model for forward simulation You need to connect the inputs and outputs before running the simulation This is explained in the next section 31 7 5 Setting up and running simulation The simulink model arm mdl which
28. ressed in global reference frame and can be modified in runtime as desired To apply external forces from Simulink you must choose the number of forces and torques when you use MMS to build your simulink model For an example see chapter 6 5 Using MMS to build Simulink models from SIMM model If you have prepared the input model files such as joint and muscle files following the SIMM s guidelines and additional guidelines in the previous chapter you are ready to use MMS to build simulink model for forward dynamic simulation First run SIMM load your SIMM model select save dynamics from the file menu check all the options for forward simulation and select the model directory where you Joint and muscle files reside and click OK This will generate all necessary files and save them to a subdirectory called forward in your model directory To run MMS open Matlab s command window in your model directory and run MMS script as follows gt gt MMS You will be asked gt gt Have you changed any of SIMM model files Y N N If you have changed the joint file or you are not sure answer yes Y This will force regeneration and recompilation of the dynamic files for the modified skeletal topology If you answer yes you will also be reminded that you should have run SIMM to regenerate model specific files for the modified model topology The default answer is no N which means the joint file has not been cha
29. t outputs the XYZ components of the angular velocity of the segment expressed in the segment s local reference frame 16 Inclinometer simulates a 3 axis inclinometer attached to a segment and aligned with its local coordinate frame Therefore it outputs the projections of the gravity vector on the XYZ axes of the segment s local reference frame Muscle spindle outputs the primary and secondary afferents firing rates Outputs for storage and animation Here the skeletal and muscle states are all sent to an output animation file called motdata mat This file is later used to generate SIMM compatible motion file for viewing the results of simulation in graphic rich SIMM environment 17 6 3 Parameters of the simulink model To see the parameters double click on the simulink model and then double click on the block named forward You will see a dialog box similar to the following Block Parameters Forward x m S Function User definable block Blocks may be written in M C Fortran or Ada and must conform to S function standards t x u and flag are automatically passed to the S function by Simulink Extra parameters may be specified in the S function parameters field m Parameters S function name forward S function parameters 1 1202009 9L OL 1 OLA 01 1 0J 0 0 0 01 1e 006 201 10 DK Cancel Help Apply Generally you must not change any of these parameters But you may need to cha
30. to a segment the vector represents the position of the sensor in segment s local reference frame When the sensor attach to a muscle only the middle number will be used as the fraction of the muscle from its origin where the sensor will attach 20 6 4 Running a simulation and viewing the results Once the simulink block is connected properly to the appropriate inputs and outputs and parameters are adjusted properly you are ready to run your simulation Set up your simulation by adjusting the Simulink s simulation parameters simulation time integration method etc and select start from simulation menu in Simulink When the simulation is complete run Matlab2SIMM script from your Matlab command prompt by typing gt gt Matlab2SIMM When asked enter a file name to save the motion data Once created you can load the motion file into the SIMM and animate the simulated movement 21 7 A simple model of arm an example In the previous chapters you learned how to build a forward dynamic model in SIMM convert it to a simulink model setup and run your simulation and view the final results back in SIMM However it is always useful to demonstrate the actual use of the procedures by an example Here I will use a simple arm model to go through the complete process of model building and simulation 22 7 1 Model description The model is a simple arm model with two segments and one degrees of freedom in elbow The two segmen
31. ts are right humerus and right ulna that are connected according to the following figure R_Humerus Elb_Ext Long Elb_Flex Elbow Joint Elb Ext Short Wrap Object R Ulna A pin joint with one degree of freedom models the elbow joint Three muscles Elb Flex Elb Ext Long Elb Ext Short act on the elbow joint Two wrap objects are used to keep the elbow muscles in appropriate side of the joint Note that the model parameters such as mass inertia are chosen arbitrarily for this example and are not representative of any age group 23 7 2 Skeletal model Skeletal model is defined in the following joint file according to the guidelines in the SIMM s documentation name ARM muscle file arm msl feeder SEGMENTS gi 1 di beginsegment r_humerus beginfiles r_humerus asc endfiles mass 1 000000 masscenter 0 000000 0 110000 0 000000 inertia 0 0100000000 0 0000000000 0 0000000000 0 0000000000 0 0010000000 0 0000000000 0 0000000000 0 0000000000 0 0100000000 axes 0 2 endsegment beginsegment r_ulna beginfiles r_ulna asc r_radius asc r_hand asc endfiles mass 1 000000 masscenter 0 000000 0 140000 0 000000 inertia 0 0100000000 0 0000000000 0 0000000000 0 0000000000 0 0010000000 0 0000000000 0 0000000000 0 0000000000 0 0100000000 axes 0 2 endsegment a hi JOINTS Pee RE REE EERE ee EER EEE EAE EASE beginjoint r_elbow segments r_humerus r_ulna order t r3 r2 r1 axis1 1 000000
Download Pdf Manuals
Related Search