Finite Element Human Body Model-based Injury Prediction using Machine Learning: Development of simulation-based surrogate models for injury metrics
Typ
Examensarbete för masterexamen
Program
Publicerad
2021
Författare
Niranjan Poojary, Yash
Srinivas, Akhil
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Models of the human body, both physical and virtual, have been vital tools for the
design of safer vehicles. Finite element models of the human body are now becoming
widely used for evaluating safety systems. With the introduction of future designs
like autonomous vehicles that affect the nature of vehicle crashes, HBM will become
a necessary tool to assess safety. Detailed human anatomy representation in HBM,
however, makes it computationally expensive and consumes a lot of time to simulate
crash scenarios. The aim of this thesis was to evaluate machine learning models as
computationally inexpensive surrogates for injury metrics from human body models.
Machine learning was performed on outputs from two types of finite element models,
crash test dummy (Hybrid III M50 fast model) and the human body (SAFER
model). Different types of model outputs namely kinematics, kinetics, injury metrics,
and injury risks used for injury evaluation were studied. Linear regressionbased
models (Ordinary, Lasso, Ridge) were used as the baseline models. Advanced
tree-based methods (Random Forest, Gradient boosted, XGBoost, Histogram-based
gradient boost) and Gaussian process regression were used to build additional machine
learning models. The machine learning pipeline comprised of data preparation,
model validation using the k-Fold cross-validation method, and model optimization
using hyperparameter tuning methods such as random search and grid search. In
these methods, the number of simulations required to achieve accurate models was
evaluated.
This thesis provides representative model learning curves (model accuracy vs number
of simulations) for the various HBM outputs. The accuracy of the models was seen
to be highly dependent on data transformation if the HBM outputs were skewed. It
was also seen that estimation of numerical noise needs to be considered as part of
the ML pipeline for HBM data to avoid overfitting in the pursuit of accuracy. For
the HBM outputs considered in this study, tree-based boosting methods provided
accurate models in most cases.
Beskrivning
Ämne/nyckelord
Finite Element (FE) , Human Body Model (HBM) , surrogate models , Injury risks , Injury criteria , Machine Learning , Hybrid III M50 fast model , SAFER HBM , Numerical Noise