Simulating ingress and egress motion for heavy earthmoving machines

Design of heavy earthmoving equipment is based primarily on feedback from drivers. Most design studies on ingress and egress focus on the motion itself and rely heavily on experimental data. This process requires physical construction of expensive (in terms of time and money) mockups before any feedback can be obtained. Post-feedback design changes and the analysis of those changes are again expensive processes. Although the design of heavy vehicles requires consideration of human safety and comfort, very little attention has been given to simulating ingress and egress movement for these vehicles. This thesis describes the development of a virtual model to perform ingress and egress motions for heavy equipment and its applications to study the responses of operators with different anthropometries to different cab designs. Different performance measures are suggested and used with predictive dynamics to study human performance since human motion is not governed by a single performance measure. Optimizing multiple performance measures allows the full range of motion for all 55 degrees of freedom to be considered for simulating the task. Once the relevant performance measure was established, case studies were performed on seven different cab designs and digital human models with three different anthropometries. Finally, several different cab design metrics for propensity of injury, comfort, and accessibility were proposed. These design metrics were evaluated for each of the case studies. Finally, each cab design was ranked based on the design metrics to identify the best design for a range of anthropometries. These results help designers make decisions and plan further design changes.