musclemodelR is an R package that is used to simulate the dynamic interaction between Hill-type muscle models and linear elastic elements. The basic code was originally developed to simulate fixed-end contractions (i.e., no change in muscle-tendon unit length), but since has been expanded to study active lengthening of muscles. Currently, the models are used to simulate the effect of tendons on 1) deceleration of mass and 2) direct lengthening of the muscle-tendon unit during muscle activation.
The easiest way to install this package is to use the
install_bitbucket() function from the
If you have problems installing
devtools, you can find more information at its github page.
musclemodelR after successful installation of
devtools::install_bitbucket(repo = "michaelvrosario/musclemodelR")
This may take a while because it will install
musclemodelR as well as any dependencies.
The following example demonstrates the framework for simulating the effect of muscle activation in conjunction with a constant rate of muscle-tendon unit elongation.
# load package library(musclemodelR) # set up inputs to simulation dt <- 1/1000 # s Fmax <- 100 # N v_mus_max <- 10 # ML/s m_muscle <- 0.5 # kg l_muscle <- 70 # mm l_spring <- 42 # mm based on matson k <- 50 # N/mm - based on initial calculations actDynamics <- F # 100% activation maxActivation <- 1 # maximal muscle activation lengthenRate <- -5 # mm/s lengthenDuration <- 0.100 # s deactivationDuration <- 0.150 # s stim_start <- 0 stim_end <- 0.100 initialConditions <- data.frame( dt, Fmax, v_mus_max, m_muscle, l_muscle, l_spring, k, actDynamics, maxActivation, lengthenRate, lengthenDuration, deactivationDuration, stim_start, stim_end ) # run simulation and export to *.JSON file RunSimulations_lengthening(inputParams = initialConditions, previousResults = F, JSONfile = "simulationResults_lengthen.JSON")
create simulation of direct lengthening generalize deceleration code for recycling setup lengthening simulations after experimental data create script to analyze lengthening results modify deceleration analysis to investigate effect of mass include installation and usage in wiki create documentation of functions using oxygen generalize functions to include stimulation parameters simulate deactivation with activation, split data into lengthening and not fix lengthening unit tests add indexing parameter for analysis fxns (DIY query) add r package documentation look up how to document package and make manual
- fix activation code for deactivation ramp
- implement intermediate unit testing
iterate though tendon stiffness?
- get a good estimate of combined FMax of all muscles connected to spring
calculate tendon stiffness from lengthening experimental data829Mpa -> 378N/mm