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diff --git a/doc/results.tex b/doc/results.tex index 8a2e5a1..21814e4 100644 --- a/doc/results.tex +++ b/doc/results.tex @@ -3,18 +3,67 @@ \section{Reflexes in Simple Leg Model} -\TODO{Describe results} +The simulation of the \emph{Simple Leg Model} led to the expected stretch reflex behavior. Given an initial +activation of the \emph{Rectus Femoris}, the \emph{Biceps Femoris} was caused to shorten proportional to the +speed of the shortening of the \emph{Rectus Femoris}. Since this will again cause \emph{Rectus Femoris} to be +shortened, the reflex is triggered in the other direction. For initial tests, the knee joint in the model was +fixed in all but one degree of freedom (pin joint) in order to permit flexion and tension. Unfortunately this +didn't lead to a realistic behavior with respect to the movement of the lower leg, as the knee joint remained +fixed during the entire simulation (see figure \ref{fig:simpleleg_sequence} for a sequence of two stretch +cycles). However since this simulation served as a test of the principal methods and the results were +satisfying enough, this problem was not further investigated. -\section{Random Data} +\begin{figure}[htb!] +\centering +\includegraphics[width=\textwidth]{images/simple_leg_sequence.png} +\caption{Sequence of the \emph{SimpleLeg} model during simulation of two cycles of the stretch reflex.} +\label{fig:simpleleg_sequence} +\end{figure} -In order to validate the principal working of the two-legged musculoskeletal model (see section \ref{subsec:two_legged_model}) and the corresponding controller (see section \ref{subsec:locomotor_primitives_controller}), random data resembling muscle activation patterns was generated for all the 53 muscles of the model. +\section{Random Data in Two-Legged Model} -\TODO{Add example plot} +In order to validate the principal working of the two-legged musculoskeletal model (see section +\ref{subsec:two_legged_model}) and to test the corresponding controller (see section +\ref{subsec:locomotor_primitives_controller}), random data resembling muscle activation patterns was generated +for all the 32 muscles of the model. In the initial version, the data contained discontinuities and the +activation values were generally too high. As a consequence, the simulation of the model took very long or in +some situations didn't complete at all. -Problems with random data: discontinuities, not fitted to muscle model and musculoskeletal model. Simulation time thus very high (or even unable to simulate). Smoothing of data needed, smaller activations. Works, but leads to unrealistic behavior. +Thus the script used to generate the data was adjusted in order to smoothen the data and provide smaller +activation values. With this second set of data, the simulation succeeded, but of course showed unrealistic +behavior. Since the simulation now completed with any type of generated pattern, the model and controller were +considered ready for usage with the real data. -\section{Locomotor Primitives Study Data} +\section{Locomotor Primitive Patterns in Two-Legged Model} -\TODO{Add example plot} +Only results for an adult subject was obtained using the locomotor primitive patterns (rightmost two columns in figure \ref{fig:dominici_patterns_graphs}). The simulation was run for $1.5$, $2.0$, $2.5$ and $3.0$ seconds respectively. The locomotor patterns were scaled to the according timespan. The visualization of a part of the simulation run is shown in figure \ref{fig:locomotor_primitives_sequence}. -\TODO{Add example image sequence of simulation}
\ No newline at end of file +It can be seen from the sequence that the muscle activations lead to an unrealistic movement of the legs (knees +bending backwards, twisting of the feet). Part of the effect can be attributed to the improper scaling of the +muscle activations. Thus different scalings factors were tried ($0.25$, $0.33$, $0.5$, $0.66$ and $0.75$) but +with all of them the basic improper movement pattern remained. + +\begin{figure}[htb!] +\centering +\includegraphics[width=\textwidth]{images/locomotor_primitives_sequence.png} +\caption{Sequence of the two-legged \emph{LocomotorPrimitives} model. Only the first $1.2$ seconds are + visualized. Total duration of simulation: $3.0$ seconds.} +\label{fig:locomotor_primitives_sequence} +\end{figure} + +When looking at the exerted muscle forces for a simulation run with the muscle activations scaled by $0.25$ +(figure \ref{fig:locomotor_primitives_reported_forces}), the activations are only partially reflected. For the +\emph{Biceps Femoris-Long Head} and the \emph{Semimembranosus} (which are both part of the hamstring muscle +group, see section \ref{subsec:two_legged_model}) the reported forces match the muscle activation patterns (see +figure \ref{fig:dominici_patterns_graphs}) quite closely, while in the case of the \emph{Soleus} and the +\emph{Rectus Femoris}, the patterns don't directly reflect the activations. Overall the exerted forces don't +show unrealistically high values. + +\begin{figure}[htb!] +\centering +\includegraphics[width=\textwidth]{images/locomotor_primitives_reported_forces.png} +\caption{Muscle forces exerted on the model during simulation for the muscles \emph{Soleus (soleus)}, + \emph{Rectus Femoris (rect\_fem)}, \emph{Semimembranosus (semimem)} and \emph{Biceps Femoris-Long Head + (bifemlh)} in both legs. X-axis is time from $0.0$--$3.0$ seconds, Y-axis is force in $N$.} +\label{fig:locomotor_primitives_reported_forces} +\end{figure}
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