Planning Smooth and Obstacle-Avoiding B-Spline Paths for Autonomous Mining Vehicles

We study the problem of automatic generation of smooth and obstacle-avoiding planar paths for efficient guidance of autonomous mining vehicles. Fast traversal of a path is of special interest. We consider four-wheel four-gear articulated vehicles and assume that we have an a priori knowledge of the mine wall environment in the form of polygonal chains. Computing quartic uniform B-spline curves, minimizing curvature variation, staying at least at a proposed safety margin distance from the mine walls, we plan high speed paths. We present a study where our implementations are successfully applied on eight path-planning cases arising from real-world mining data provided by the Swedish mining company Luossavaara-Kiirunavaara AB (LKAB). The results from the study indicate that our proposed methods for computing obstacle-avoiding minimum curvature variation B-splines yield paths that are substantially better than the ones used by LKAB today. Our simulations show that, with an average 32.13%, the new paths are faster to travel along than the paths currently in use. Preliminary results from the production at LKAB show an overall 5%-10% decrease in the total time for an entire mining cycle. Such a cycle includes both traveling, ore loading, and unloading. Note to Practitioners-This article was motivated by the problem of how to automatically produce high quality drive-paths for autonomous transportation vehicles in mines. The vehicles are heavy (100 tonnes) but are still expected to run at speeds up to 20 km/h to be productive. To reach these speeds without damaging the steering gear and the mechanics of the vehicles, their paths need to be smooth. It turns out that visual inspection is often insufficient to produce a path with high smoothness. We suggest a method for computing paths, requiring an a priori knowledge about the environment, that minimizes the amount of steering needed. The computed paths are safe as they guarantee no collisions between the vehicle and the tunnel wall. We present a study of eight cases based on real-world application data from the Swedish mining company Luossavaara-Kiirunavaara AB (LKAB) showing that, with an average of 32.13%, our paths are faster to travel along than the paths currently in use.