• A Voronoi-diagram-based dynamic path-planning system for underactuated marine vessels 

      Candeloro, Mauro; Lekkas, Anastasios M.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2017)
      The main contribution of this paper is the development of a rapid, dynamic path-planning system for 3-DOF marine surface vessels navigating in environments where other marine vehicles might be operating too. The method is ...
    • Autonomous docking using direct optimal control 

      Martinsen, Andreas Bell; Lekkas, Anastasios M.; Gros, Sebastien (Journal article; Peer reviewed, 2019)
      We propose a method for performing autonomous docking of marine vessels using numerical optimal control. The task is framed as a dynamic positioning problem, with the addition of spatial constraints that ensure collision ...
    • Curved Path Following with Deep Reinforcement Learning: Results from Three Vessel Models 

      Martinsen, Andreas Bell; Lekkas, Anastasios M. (Chapter, 2018)
      This paper proposes a methodology for solving the curved path following problem for underactuated vehicles under unknown ocean current influence using deep reinforcement learning. Three dynamic models of high complexity ...
    • Energy-Optimized Path Planning for Autonomous Ferries 

      Bitar, Glenn Ivan; Breivik, Morten; Lekkas, Anastasios M. (Journal article, 2018)
      The topic of energy-optimized path planning using pseudospectral optimal control is considered. An optimal control problem (OCP) is formulated to produce an energy-optimized path between two points among static obstacles. ...
    • Guidance and Path-Planning Systems for Autonomous Vehicles 

      Lekkas, Anastasios M. (Doktoravhandlinger ved NTNU, 1503-8181; 2014:126, Doctoral thesis, 2014)
      This thesis is concerned with two interconnected and very important problems regarding the autonomy of vehicles, namely, path planning and guidance. By adopting a modular approach, path planning and guidance can be viewed ...
    • Hybrid Collision Avoidance for ASVs Compliant with COLREGs Rules 8 and 13-17 

      Eriksen, Bjørn-Olav Holtung; Bitar, Glenn Ivan; Breivik, Morten; Lekkas, Anastasios M. (Journal article; Peer reviewed, 2020)
      This paper presents a three-layered hybrid collision avoidance (COLAV) system for autonomous surface vehicles, compliant with rules 8 and 13–17 of the International Regulations for Preventing Collisions at Sea (COLREGs). ...
    • Online Path Planning for Surface Vehicles Exposed to Unknown Ocean Currents Using Pseudospectral Optimal Control 

      Lekkas, Anastasios M.; Roald, Ann Louise; Breivik, Morten (Journal article; Peer reviewed, 2016)
      This paper investigates the feasibility of using pseudospectral (PS) optimal control in real-time path planning for marine surface vehicles in environments where both obstacles and unknown disturbances are present. In ...
    • Straight-Path Following for Underactuated Marine Vessels using Deep Reinforcement Learning 

      Martinsen, Andreas Bell; Lekkas, Anastasios M. (Chapter, 2018)
      We propose a new framework, based on reinforcement learning, for solving the straight-path following problem for underactuated marine vessels under the influence of unknown ocean current. A dynamic model from the Marine ...
    • Warm-Started Optimized Trajectory Planning for ASVs 

      Bitar, Glenn Ivan; Vestad, Vegard Nitter; Lekkas, Anastasios M.; Breivik, Morten (Journal article; Peer reviewed, 2019)
      We consider warm-started optimized trajectory planning for autonomous surface vehicles (ASVs) by combining the advantages of two types of planners: an A* implementation that quickly finds the shortest piecewise linear path, ...