  Driving heavy-duty vehicles, such as buses and tractor-trailer vehicles, is a
difficult task in comparison to passenger cars. Most research on motion
planning for autonomous vehicles has focused on passenger vehicles, and many
unique challenges associated with heavy-duty vehicles remain open. However,
recent works have started to tackle the particular difficulties related to
on-road motion planning for buses and tractor-trailer vehicles using numerical
optimization approaches. In this work, we propose a framework to design an
optimization objective to be used in motion planners. Based on geometric
derivations, the method finds the optimal trade-off between the conflicting
objectives of centering different axles of the vehicle in the lane. For the
buses, we consider the front and rear axles trade-off, whereas for articulated
vehicles, we consider the tractor and trailer rear axles trade-off. Our results
show that the proposed design strategy results in planned paths that
considerably improve the behavior of heavy-duty vehicles by keeping the whole
vehicle body in the center of the lane.
