# Development of a Simplified Human Body Model for Movement Simulations
## 4 Discussion
However, significant changes were also introduced in the simplified model. First of all, although the models are parameterized using anthropometric data, the Hanavan model requires the measurement of as many as 25 body dimensions, while the simplified model associates all the values with the height and mass of a human. Moreover, differences also concern the partitioning into individual body segments: 15 in Hanavan, while the simplified model contains 17 segments, including 16 connected in a movable way. Taking all the presented features into consideration, the developed model may be called a modified Hanavan human body model. A further comparison with several existing models is presented in Table 2: Hanavan [16], Hatze [17], Yaedon [18], Pecolt [30], and Nagano [31]. All models divide the human body into rigid solids with a generally uniform density. The main differences are the number of required human body measurements, as well as the total number of segments and solids contained in the model. Some consider gender and factors like pregnancy or being overweight. The developed model represents a significant simplification compared to the existing models described in Table 2. While these models often require numerous measurements (ranging from 25 in Hanavan to 242 in Hatze) and incorporate complex segment geometries and varying densities, the developed model relies on only two parameters (height and \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Name of Model** & **No. of Measurements/Segments** & **Geometry of Segments** & **Features of Solids** & **Type of Connections** & **Additional Features** \\ \hline \multirow{3}{*}{Hanavan model} & \multirow{3}{*}{25/15} & Single solids with simple shapes & \begin{tabular}{c} Rigid solids \\ Uniform density \\ Specified \\ COM position \\ \end{tabular} & \multirow{3}{*}{\
\begin{tabular}{c} Spherical joints with \\ zero mass \\ \end{tabular} } & \multirow{3}{*}{
\begin{tabular}{c} Assumes symmetry of \\ body segments \\ \end{tabular} } \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of the developed model’s main features with several existing model solutions. mass). Furthermore, based solely on these two easily obtainable anthropometric measurements, the developed model achieves full parameterization of segment dimensions and masses. This is another significant advantage over models that rely on numerous and potentially less accessible measurements. At the same time, the developed model also offers an advantage over models like Pecolt and Nagano, which may oversimplify segment shapes, potentially leading to inaccuracies. The simplified model, with a drastic reduction in the required measurements to enhance the model's usability, allows for faster model creation and application, making it a valuable tool for preliminary analyses and rapid prototyping. However, this simplification and parameterization, which depend only on two parameters, comes at the cost of potentially reduced model accuracy and limited applicability to individuals with various body shapes and sizes. It is difficult to determine the accuracy and performance of the models since they depend on a variety of factors, including model complexity, data quality, parameter estimation, and validation. Generally, simpler models with fewer segments and DOF are easier to develop and analyze, but may not accurately capture the complex biomechanics of human movement. More complex models, with a greater number of segments and joints, can provide more realistic simulations, but are computationally expensive, especially when real-time performance is required.