Optimal Path Smoothing using Clothoids for Autonomous Vehicles in the Quarry Environment

Sammanfattning: Autonomous vehicles are a rapidly growing field and will play an important role in future society. The introduction of autonomous machines in the quarry environment increases safety in the hazardous working conditions and reduces the risk of accidents caused by human error. By making the machine electric and autonomous it will also improve the fuel efficiency and reduces carbon emission. The results of this thesis are developed within the electric site project which is lead by Volvo Construction Equipment in Eskilstuna, Sweden. The goal is to transform the quarry and aggregates with the help of the introduction of electric hybrid autonomous machines which is predicted to result in reduced carbon emission by up to 95% .This thesis address the problem of path planning noisy curvatures of the paths that are calculated using coordinates recorded from a manual driven vehicle. This makes the control algorithm for the autonomous vehicle hard to implement. The purpose in this thesis is to develop a procedure to describe paths and smooth those so the curvature becomes smooth and drivable for an autonomous load carrier. To smooth the paths, we use the concept of clothoids which are curves with linear varying curvature. Clothoids are widely used in road design because of its smoothness properties. We solve the smoothing problem by formulating it as an optimization problem where we minimize the number of clothoid segments to avoid unnecessary noisy curvature variations. The results are successful and we are able to produce feasible paths for two test tracks Volvo Construction Equipment uses. We also create a Graphical User Interface in MATLAB to facilitate the creation of the clothoid-based paths from recorded GPS coordinates