Path-following algorithms and experiments for an autonomous surface vehicle

This paper addresses the problem of path-following in two-dimensional space, for underactuated surface autonomous robots, defining a set of guidance laws either at kinematic and dynamic level. The proposed nonlinear Lyapunov- based control law yields convergence of the path following error coordinates to zero. Furthermore, the introduction of a dynamic for the target to be followed on the path, removes singularity behaviors present in other guidance algorithms proposed in the literature. Dynamic of the vehicle is then taken into account, applying the Backstepping technique. Some heuristic approaches are then proposed to face the problem of speed of advance adaptation based on path curvature measure and steering action prediction. Finally a set of experimental results of all the proposed guidance laws are presented.