  Mobile robots in dynamic environments require fast planning, especially when
onboard computational resources are limited. While classic potential field
based algorithms may suffice in simple scenarios, in most cases algorithms able
to escape local minima are necessary. Configuration-space search algorithms
have proven to provide a good trade-off between quality of the solutions and
search time. Literature presents a wide variety of approaches that speed up
this search by reducing the number of edges that need to be inspected. Much
less attention was instead given to reducing the time necessary to evaluate the
cost of a single edge. This paper addresses this point by associating edges to
motion primitives that prioritize fast collision detection. We show how biarcs
can be used as motion primitives that enable fast collision detection, while
still providing smooth, tangent continuous paths. The proposed approach does
not assume a disc shaped hitbox, making it appealing for all robots with very
different width and length or for differential drive robots with active wheels
located far from the robot's center.
