Integral Line-of-Sight Guidance and Control of Underactuated Marine Vehicles: Theory, Simulations, and Experiments

Abstract

Abstract-This paper presents an extensive analysis of the integral line-of-sight (ILOS) guidance method for path following tasks of underactuated marine vehicles, operating on and below the sea surface. It is shown that due to the embedded integral action, the guidance law makes the vessels follow straight lines by compensating for the drift effect of environmental disturbances such as currents, wind and waves. The ILOS guidance is first applied to a 2D model of surface vessels that includes the underactauted sway dynamics of the vehicle as well as disturbances in the form of constant irrotational ocean currents and constant dynamic, attitude dependent, forces. The actuated dynamics are not taken into account at this point. A Lyapunov closed loop analysis yields explicit bounds on the guidance law gains to guarantee uniform global asymptotic stability (UGAS) and uniform local exponential stability (ULES).The complete kinematic and dynamic closed loop system of the 3D ILOS guidance law is analyzed next, hence extending the analysis to underactuated AUVs for 3D straight-line path following applications in the presence of constant irrotational ocean currents. The actuated surge, pitch and yaw dynamics are included in the analysis where the closed loop system forms a cascade, and the properties of UGAS and ULES are shown. The 3D ILOS control system is a generalization of the 2D ILOS guidance. Finally, results from simulations and experiments are presented to validate and illustrate the theoretical results, where the 2D ILOS guidance is applied to the CART and the LAUV vehicles.

A hybrid approach to underwater docking of AUVs with cross-current

“…During the approaching path, the AUV follows a straight line parallel to the centerline of the docking station. Due to the presence of cross-current, the component of the current perpendicular to the path, the vehicle needs to keep a certain crab angle in order to stay on the path [13]. Once the vehicle gets closer to the docking station, it changes to the sliding path that leads to the entrance of the docking station.…”

“…During the approaching path, the vehicle is guided by an Integral Line of Sight (ILOS) [13] guidance law (see 3). Then, when the vehicle reaches the sliding path, two guidance laws, an ILOS and a Speed Regulated Guidance (SRG), are combined with a hybrid framework in order to achieve the objectives 6a-6c.…”

“…[15] or through lookup tables. Based on these measurements and estimates, or using a DVL without bottom lock, the relative surge speed is measured/calculated, and a speed controller like for instance the feedback linearizing speed controller in [13] will maintain the desired relative surge speed U rd with exponential convergence.…”

Uniform Semiglobal Exponential Stability of Integral Line-of-Sight Guidance Laws∗∗This work was partly supported by the Research Council of Norway through the Centres of Excellence funding scheme, project no. 223254 - AMOS

“…Global κ-exponential stability of the ILOS guidance law in closed loop with the kinematic model is proved. Caharija et al (2015) combines the kinematic and kinetic disturbance models and proves global κ-exponential stability of the ILOS guidance law in combination with a vessel model containing kinematics and dynamics. Caharija et al (2015) also examines the stability properties of a 3 dimensional ILOS guidance law for an underwater vehicle modeled in 5-DOF, again proving global κ-exponential stability of the system.…”

“…Caharija et al (2015) combines the kinematic and kinetic disturbance models and proves global κ-exponential stability of the ILOS guidance law in combination with a vessel model containing kinematics and dynamics. Caharija et al (2015) also examines the stability properties of a 3 dimensional ILOS guidance law for an underwater vehicle modeled in 5-DOF, again proving global κ-exponential stability of the system. modifies the integral term used in Børhaug et al (2008) to achieve integral action using adaptive sideslip estimation, and is able to prove USGES for a closed loop kinematic model of an underactuated marine vehicle following Dubins paths (Dubins (1957)).…”