VECTOR FIELD GUIDANCE LAW FOR CURVED PATH FOLLOWING OF AN UNDERACTUATED AUTONOMOUS SHIP MODEL

A vector field guidance law and control system for curved path following of an underactuated surface ship model is presented in this paper. In order to obtain the curved path, continuous derivatives piecewise cubic Hermite interpolation is applied for path generation based on the predefined waypoints. A heading autopilot controller is designed based on 2nd order Nomoto’s model and its stability is guaranteed by the Diagram of Vyshnegradsky method. The parameters of Nomoto model are estimated using least square support vector machine based on the manoeuvring tests. The vector field guidance law is applied for both straight and curved path-following control of an underactuated surface ship model. In order to demonstrate the performance, the classical guidance law based on line-of-sight, is adopted for comparison. The results show that the vector field method is capable to solve the guidance problem of underactuated surface ships.

Vector Field Guidance Law for Curved Path Following of an Underactuated Autonomous Ship Model

A vector field guidance law and control system for curved path following of an underactuated surface ship model is presented in this paper. In order to obtain the curved path, continuous derivatives piecewise cubic Hermite interpolation is applied for path generation based on the predefined waypoints. A heading autopilot controller is designed based on 2nd order Nomoto’s model and its stability is guaranteed by the Diagram of Vyshnegradsky method. The parameters of Nomoto model are estimated using least square support vector machine based on the manoeuvring tests. The vector field guidance law is applied for both straight and curved path-following control of an underactuated surface ship model. In order to demonstrate the performance, the classical guidance law based on line-of-sight, is adopted for comparison. The results show that the vector field method is capable to solve the guidance problem of underactuated surface ships.

Cooperative Standoff Tracking of Moving Targets Using Modified Lyapunov Vector Field Guidance

Cooperative standoff tracking of moving targets is an important application of fixed-wing unmanned aerial vehicles (UAVs). To cope with the problem of long convergence time and unstable tracking in cooperative target tracking, traditional Lyapunov vector field guidance (LVFG) is modified. The guidance parameter c is discussed, and the gradient descent method is utilized to develop the optimal guidance parameter search algorithm. As for tracking moving targets, an interacting multiple model-based unscented Kalman filter (IMM-UKF) estimator is built for predicting the target state, and the result is used for correcting the guidance law. Meanwhile, a speed-based controller is developed for faster convergence to the desired intervehicle phase, and the stability of the controller is proved using the Lyapunov stability theory. Numerical simulation results indicate the proposed guidance converges faster to the standoff circle without intersecting the orbit. The state estimator reduces the estimate error and the intervehicle phase converges faster to the desired phase than the traditional control method. Furthermore, extensive hardware-in-the-loop simulations are carried out to verify the feasibility of the algorithm.

Time-Varying Vector Field Guidance Law for Path Following and Obstacle Avoidance for Underactuated Autonomous Vehicles

This paper presents a time-varying vector field guidance law for path-following control of underactuated autonomous vehicles. The proposed guidance law employs a time-varying equation to calculate the desired heading angle. A sliding mode controller is designed to track the desired heading angle, and it is proved to be globally exponentially stable (GES). With this controller, the stability proof for guidance system is presented and the equilibrium point of the guidance system is Uniform Global Asymptotic Stable (UGAS). In order to avoid the obstacle when ship approaching the predefined path, a combined Path-following and repelling field based obstacle avoidance system is proposed in this paper. Simulations are carried out to validate the performance of the combined path-following and collision avoidance system.