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Selection of Modelling Level of Detail for Incorporating Stress Analysis into Evolutionary Robotics Simulations of Extinct and Extant Vertebrates
[Thesis]. Manchester, UK: The University of Manchester; 2015.
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Abstract
This thesis concerns the simulation of locomotion in vertebrates. The state-of-theartuses genetic algorithms together with solid body kinematics to generate possiblesolutions for stable gaits. In recent work, this methodology led to a hopping gait in adinosaur and the researchers wondered if this was realistic. The purpose of theresearch carried out in this thesis was to examine whether quick and simple finiteelement analyses could be added to the simulator, to evaluate a simple ―break or―not break failure criterion. A break would rule out gaits that might damage theowner‘s skeleton. Linear elastic analysis was considered as a possible approach as itwould add little overhead to the simulations.The author used X-ray computed tomography and the finite element method toexamine the axial loading of a barnacle goose femur. The study considered fourlevels of detail for a linear elastic simulation, finding that all the analyses carried outoverestimated the strength of the bone, when considering safety factors. Theconclusion is that to incorporate stress-strain analysis into the gait simulationrequires more realistic models of bone behaviour that incorporate the nonlinearresponse of bone to applied loading. A new study focusing on the use of noveltechniques such as model order reduction is recommended for future work.The outputs of this research include chapters written up as journal papers covering a4D tomography experiment; a level of detail study; an analysis of a purported tendonavulsion injury in Tyrannosaurus rex and a review of the elastic properties of bone.
Layman's Abstract
This thesis concerns the simulation of locomotion in vertebrates. The state-of-theartuses genetic algorithms together with solid body kinematics to generate possiblesolutions for stable gaits. In recent work, this methodology led to a hopping gait in adinosaur and the researchers wondered if this was realistic. The purpose of theresearch carried out in this thesis was to examine whether quick and simple finiteelement analyses could be added to the simulator, to evaluate a simple ―break or―not break failure criterion. A break would rule out gaits that might damage theowner‘s skeleton. Linear elastic analysis was considered as a possible approach as itwould add little overhead to the simulations.The author used X-ray computed tomography and the finite element method toexamine the axial loading of a barnacle goose femur. The study considered fourlevels of detail for a linear elastic simulation, finding that all the analyses carried outoverestimated the strength of the bone, when considering safety factors. Theconclusion is that to incorporate stress-strain analysis into the gait simulationrequires more realistic models of bone behaviour that incorporate the nonlinearresponse of bone to applied loading. A new study focusing on the use of noveltechniques such as model order reduction is recommended for future work.The outputs of this research include chapters written up as journal papers covering a4D tomography experiment; a level of detail study; an analysis of a purported tendonavulsion injury in Tyrannosaurus rex and a review of the elastic properties of bone.