An Automatic Collision Avoidance Algorithm for Multiple Marine Surface Vehicles

Abstract

In recent years, unmanned surface vehicles have been widely used in various applications from military to civil domains. Seaports are crowded and ship accidents have increased. Thus, collision accidents occur frequently mainly due to human errors even though international regulations for preventing collisions at seas (COLREGs) have been established. In this paper, we propose a real-time obstacle avoidance algorithm for multiple autonomous surface vehicles based on constrained convex optimization. The proposed method is simple and fast in its implementation, and the solution converges to the optimal decision. The algorithm is combined with the PD-feedback linearization controller to track the generated path and to reach the target safely. Forces and azimuth angles are efficiently distributed using a control allocation technique. To show the effectiveness of the proposed collision-free path-planning algorithm, numerical simulations are performed.

Optimization of Controlled Free-Time Sweeping Processes with Applications to Marine Surface Vehicle Modeling

“…Each USV aims at reaching the target by the shortest pass with the minimum time T while avoiding the other n − 1 static and/or dynamic obstacles. The dynamics of this model are described in [9] as an uncontrolled sweeping process.…”

“…In the absence of obstacles, the desired velocities are given by V (x) = g(x) ∈ R 2n . In the presence of obstacles, the algorithm in [9] seeks for optimal velocities to escape from surrounding obstacles by solving the following convex constrained optimization problem:…”

“…The algorithmic design in (9) means that V k+1 is selected as the unique element from the set of admissible velocities as the one closest to the desired velocity g(x, u) while avoiding overlapping. Consequently, the proposed scheme seeks for new directions V (x) of USVs close to the desired direction g(x, u) in order to bypass the surrounding obstacles.…”

“…for all t ∈ (t k i , t k i+1 ). As discussed in [9], the solutions to (12) in the uncontrolled setting of ( 11) with g = g(x(t)) uniformly converge on [0, T k ] to a trajectory of a certain perturbed sweeping process. The controlled model under consideration here is significantly more involved.…”

Unifying Reactive Collision Avoidance and Control Allocation for Multi-Vehicle Systems

“…In such a controller, the reactive algorithm ensures the safety of the vehicle in unexpected situations. Such an algorithm is proposed in [19], where a collision-free velocity reference is obtained through numerical optimization. The proposed algorithm is designed specifically for autonomous surface vehicles (ASVs).…”