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Adaptive Line-Of-Sight guidance law based on vector fields path following for underactuated unmanned surface vehicle

Jie Qi, Ronghua Wanga, Nailong Wu

TL;DR

The paper addresses robust path following for underactuated USVs in disturbed aquatic environments. It introduces a vector-field–based adaptive LOS law (VFALOS) that integrates a curved-path vector field and adaptive sideslip estimation, with heading commands expressed as $\psi_d=\gamma_p-\hat{\beta}-\arctan\left(\frac{y_e}{\Delta}\right)\dot{\hat{\beta}}$ for straight segments and $\psi_d=\gamma_c-\frac{\pi}{2}-\hat{\beta}-\arctan\left(\frac{d-r_v}{\Delta}\right)\dot{\hat{\beta}}$ for curves. A Lyapunov-based analysis shows global $\kappa$-exponential convergence via $V=\frac{1}{2}(d-r_v)^2+\frac{U}{2\gamma}\tilde{\beta}^2$, confirming UGAS/ULES; a curved-path radius $r_v$ shapes the vector field and the speed law $U_d$ adapts to errors. Simulations and lake experiments in ROS demonstrate improved tracking accuracy and reduced overshoot compared with VFILOS and TLOS, validating robustness to disturbances. Overall, VFALOS provides a faster, more stable, curved-path tracking framework for USVs with practical implications for autonomous maritime missions.

Abstract

The focus of this paper is to develop a methodology that enables an unmanned surface vehicle (USV) to efficiently track a planned path. The introduction of a vector field-based adaptive line of-sight guidance law (VFALOS) for accurate trajectory tracking and minimizing the overshoot response time during USV tracking of curved paths improves the overall line-of-sight (LOS) guidance method. These improvements contribute to faster convergence to the desired path, reduce oscillations, and can mitigate the effects of persistent external disturbances. It is shown that the proposed guidance law exhibits k-exponential stability when converging to the desired path consisting of straight and curved lines. The results in the paper show that the proposed method effectively improves the accuracy of the USV tracking the desired path while ensuring the safety of the USV work.

Adaptive Line-Of-Sight guidance law based on vector fields path following for underactuated unmanned surface vehicle

TL;DR

The paper addresses robust path following for underactuated USVs in disturbed aquatic environments. It introduces a vector-field–based adaptive LOS law (VFALOS) that integrates a curved-path vector field and adaptive sideslip estimation, with heading commands expressed as for straight segments and for curves. A Lyapunov-based analysis shows global -exponential convergence via , confirming UGAS/ULES; a curved-path radius shapes the vector field and the speed law adapts to errors. Simulations and lake experiments in ROS demonstrate improved tracking accuracy and reduced overshoot compared with VFILOS and TLOS, validating robustness to disturbances. Overall, VFALOS provides a faster, more stable, curved-path tracking framework for USVs with practical implications for autonomous maritime missions.

Abstract

The focus of this paper is to develop a methodology that enables an unmanned surface vehicle (USV) to efficiently track a planned path. The introduction of a vector field-based adaptive line of-sight guidance law (VFALOS) for accurate trajectory tracking and minimizing the overshoot response time during USV tracking of curved paths improves the overall line-of-sight (LOS) guidance method. These improvements contribute to faster convergence to the desired path, reduce oscillations, and can mitigate the effects of persistent external disturbances. It is shown that the proposed guidance law exhibits k-exponential stability when converging to the desired path consisting of straight and curved lines. The results in the paper show that the proposed method effectively improves the accuracy of the USV tracking the desired path while ensuring the safety of the USV work.
Paper Structure (6 sections, 1 theorem, 19 equations, 7 figures)

This paper contains 6 sections, 1 theorem, 19 equations, 7 figures.

Table of Contents

  1. Introduction
  2. USV model
  3. Vector field-based adaptive LOS guidance law
  4. Results and discussions
  5. Conclusion
  6. Acknowledgements

Key Result

Theorem 1

In the face of constant or time-varying environmental disturbances, the nominal system's point $d=r$ is globally $\kappa$-exponentially stable if the intended heading angle is represented by Eq. VFALOS3 and the time derivative of the parameter estimation is provided by Eq. VFALOS4.

Figures (7)

  • Figure 1: Flowchart of the control strategy for the LOS guidance law.
  • Figure 2: 3-DOF vessel centered at $C$ in the North-East-Down reference frame.
  • Figure 3: Schematic diagram of the guidance law.
  • Figure 4: The implementation of the USV control system.
  • Figure 5: USV path tracking renderings using three different LOS guidance laws in the simulation experiment.
  • ...and 2 more figures

Theorems & Definitions (2)

  • Theorem 1: Globally $\kappa$-Exponentially Stable VFALOS Guidance Law
  • proof