Efficient Extensible Path Planning on 3D Terrain Using Behavior Modules

We present a search-based path planning system for ground robots on three dimensional terrain. Effectively negotiating such terrain often requires to utilize dedicated robot hardware and to execute specific behaviors. Our base system is independent from the actual robot configuration, but can be customized to a robot's abilities. We explicitly plan using a full 3d representation, not requiring any projection or slicing to a 2d world. The drivable surface manifold is automatically extracted from the volumetric 3d representation and generic motions are planned on these surface cells. This is achieved with behavior modules that integrate robot skills with the search. Such a behavior module is responsible for defining traversable surfaces, computing if a motion can be executed, and its cost. We implement two such modules: One for sloped ground and ramps, and one for steps and stairs. The approach is evaluated on simulated real-world environments.